- Email: [email protected]
Esthetic alveolar ridge preservation with calcium phosphate and collagen membrane: Preliminary report
Esthetic alveolar ridge preservation with calcium phosphate and collagen membrane: Preliminary report Sasikarn Kesmas, DDS,a Somporn Swasdison, DDS, PhD,b Somchai Yodsanga, BSc,c Somchai Sessirisombat, DDS, MS, MD,d and Pornchai Jansisyanont, DDS, MS,eBangkok, Thailand CHULALONGKORN UNIVERSITY
Objective. The objective of this study was to evaluate clinically, histologically and radiographically a ridge preservation technique used on extraction sockets grafted with biphasic calcium phosphate (BCP) and a resorbable collagen membrane. Material and methods. Patients having a labial socket wall defect more than one-third in mesio-distal socket width after maxillary central incisor tooth extraction were included. The labial defect was sealed with resorbable collagen membrane and the defect filled with BCP. The grafted socket was covered with a resorbable collagen wound dressing material. The treated sockets were evaluated after a 4-month healing period when implants were placed and followed for up to 12 months. Results. There were 8 subjects enrolled in this study. A statistical difference was found only in ridge width reduction at 3 mm below the cement-enamel junction of the adjacent teeth (P ⬍ .05) with 1 mm widening at 8 mm. The amount of new bone formation was extensively varied with diminutive graft remnants. Most cells in the connective tissue were osteopontin positive indicating they were osteoblast-like cells. A declination in the radiodensity of the grafted socket was observed during the analyzed period. Conclusion. Ridge preservation with BCP with collagen membrane can be used as an alternative treatment for maintaining ridge dimension before implant placement. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010; 110:e24-e36)
Currently, oral rehabilitation with dental implants is increasing owing to their predictable outcome. Adequate alveolar ridge dimension is required for ideal implant positioning, resulting in proper function and improved esthetics in dental rehabilitation. Unfortunately, consequent to tooth loss, resorption of alveolar This study was supported by a grant from the Chulalongkorn University graduate scholarship to commemorate the 72nd anniversary of His Majesty King Bhumibol Adulyadej and a grant from the 90th Anniversary Chulalongkorn University Fund (Ratchadaphiseksomphot Endowment Fund), Chulalongkorn University, Bangkok, Thailand. The bone graft materials (BCP) were provided by Institut Straumann AG, Basel, Switzerland. a Graduate dental student, Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand. b Associate Professor, Department of Oral Pathology, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand. c Technician, Department of Oral Pathology, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand. d Associate Professor, Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand. e Assistant Professor, Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand. Received for publication Feb 23, 2010; returned for revision May 29, 2010; accepted for publication Jun 9, 2010. 1079-2104/$ - see front matter © 2010 Published by Mosby, Inc. doi:10.1016/j.tripleo.2010.06.006
e24
bone occurs as a result of physiologic healing.1 The pattern of resorption often results in a residual knife edge and a palatally or lingually shifted ridge apex, and a frail and thin labial cortex.1-3 The estimated structural loss is about 40% and 60% of preextraction alveolar ridge height and width, respectively.4 This loss has a detrimental effect on potential treatment with a dental implant or conventional prosthesis. Various techniques have been used to overcome these problems. Augmentation of the extraction socket has been used to maintain or enhance the dimensions of the alveolar bone and soft tissue based on the principle of guided bone regeneration (GBR).5-7 This procedure, also called socket augmentation or ridge preservation, can be performed using multiple types of bone graft including autogenous, allogenous, xenogenous, and alloplastic bone in combination with or without a barrier membrane. Autogenous bone is recognized to be the current “gold standard” of bone grafting material because of the viability of transferable osteogenic cells within the graft but the disadvantages of second donor site morbidity and patient discomfort have led to a decline in the popularity of this material.8 Allografts have demonstrated their osteoinductive potential9-11; however, some studies have failed to show the clinical significance of this potential.12,13 Furthermore, the un-
OOOOE Volume 110, Number 5
certain immune response and risk of disease transmission remain major problems in the clinical use of materials of this type. Recently, the use of xenografts, especially bovine bone has increased not only in ridge preservation procedures, but also other bone augmentation procedures. The important benefits of xenograft bone are a reduction of the drawbacks associated with autografts and their unlimited availability. Some studies have found that bovine bone– grafted sites demonstrated a better outcome and indicated this material could be a good bone substitute for bone augmentation before implant installation.14-16 Downsides of the use of bovine bone include its slowly resorbability and healing with fibrous encapsulation.17-19 A newly invented synthetic bone substitute composed of 60% hydroxyapatite and 40% beta-tricalcium phosphate (biphasic calcium phosphate [BCP] BoneCeramic; Straumann, Basel, Switzerland) has been introduced for use in preparing surgical sites before implant placement, and in sinus lift procedure, bone augmentation procedures, periodontal surgery, and ridge preservation procedures.20,21 This material provokes bone regeneration by its osteoconductive capacity. Beta-tricalcium phosphate, in the rapid resorption phase, can be completely resorbed and replaced by regenerative bone. This provides for faster bone remodeling. Hydroxyapatite, which is slowly resorbed, serves as a good matrix scaffold for new bone formation. This grafting material has a greater capacity than xenograft bone in enhancing new bone regeneration and can be utterly resorbed and subsequently replaced by host bone in a shorter time. However, there is a paucity of studies confirming the effectiveness of this material in preserving ridge dimension both clinically and histologically. Therefore, the purpose of this study was to clinically, histologically, and radiographically evaluate the healing of extraction sockets treated with BCP combined with a resorbable collagen membrane used as a ridge preservation technique to determine if this bone graft material might be suitable to use given that it does not suffer from the drawbacks of other bone substitutes such as autografts and allografts. MATERIAL AND METHODS Patient selection The study was designed as a prospective study with one treatment group. The study protocol was approved by the Ethics Committee of the Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand. Before enrollment in this study, all participants signed a written consent form. Patients requiring at least one upper incisor tooth to be extracted and subsequently restored with implant therapy were enrolled in this study. All procedures were carried out in the Department of Oral
Kesmas et al. e25
Fig. 1. Illustration of the socket labial bone defect that was more than one third in mesio-distal width of the socket.
and Maxillofacial Surgery, Faculty of Dentistry, Chulalongkorn University, from October 2007 to October 2009. The reasons for tooth extraction were periodontal disease, endodontic failure, advanced unrestorable caries, or tooth fracture, the diagnosis of which was confirmed by clinical and radiographic examination. The inclusion criteria were systemically healthy patients without any medically compromising conditions, and not taking any medications that would influence their ability to undergo the operation under local anesthesia or alter the healing of the bone and soft tissue. Patients were nonsmokers or previous smokers who had stopped smoking for at least 6 months. Patients with any active infection or those who could not participate through to the end of the study were excluded from the study. The extraction sockets recruited in this study required a defect of the labial bone of more than one third in mesio-distal socket width (Fig. 1). In cases where the labial socket wall was thin (bone thickness less than 1 mm) or had the defect of less than one third in mesiodistal width, the patient was excluded from the study because these clinical presentations do not indicate membrane-assisted socket grafting procedures. The treatment flow-chart is shown in Fig. 2. Evaluation of the present ridge preservation procedure focused on 3 aspects: clinical, histological, and radiographic examination. Operational procedure Preoperatively, a periapical radiograph was taken with parallel technique using an XCP instrument and a customized bite block made from a polyvinyl siloxane impression material for each patient. A 4.0-mm diameter metal ball was inserted into the customized bite
e26
Kesmas et al.
OOOOE November 2010
Fig. 2. Guideline of the treatment provided after the tooth was extracted according to the characteristic of the labial socket bone wall.
block as a radiodensity reference. Chlorhexidine gluconate, 0.2%, mouthwash was used for 1 minute and preoperative prophylaxis with amoxicillin 1 g was prescribed 1 hour before the operation. As one patient was allergic to amoxicillin, clindamycin 600 mg was prescribed to this patient. All patients received local anesthesia (2% mepivacaine with 1:100,000 epinephrine) before surgery. The affected tooth was extracted via flapless atraumatic technique. The socket was thoroughly debrided to remove granulation tissue and copiously irrigated with normal saline solution. When hemostasis in the socket was achieved, the socket wall, except the buccal surface, was perforated with a small surgical round bur exposing the marrow allowing bleeding into the socket. Following the Bio-Col technique proposed by Sclar,22 a resorbable collagen membrane, Bio-Gide (Geistlich, Pharma AG, Wolhusen, Switzerland), was inserted into the labial subperiosteal pocket to seal the socket wall defect. The socket was then augmented with BCP. No effort was made to extend the graft beyond the preexisting dimension of the socket. Subsequently, a resorbable collagen wound dressing material, Collaplug (Zimmer Dental, Carlsbad, CA), was placed over the graft to the level of the marginal gingiva to use as a soft tissue matrix. The surgical site was sutured with absorbable suture, Vicryl (Ethicon, Inc., Somerville, NJ), 4-0 with horizontal mattress or figure-of-eight suture to hold the Collaplug in place without the intention of primary closure. Postoperatively, a periapical radiograph was taken immediately as previously described. All the patients
were advised to rinse with 0.2% chlorhexidine gluconate mouthwash, 1 minute, twice daily for 2 weeks. Ibuprofen 400 mg 3 times daily for postoperative pain control and the appropriate antibiotics were prescribed postoperatively according to preoperative antibiotic prophylaxis, either amoxicillin 500 mg or clindamycin 300 mg 3 times daily for 7 days. The patients were advised not to wear any prosthesis at the surgical site during the first 2 weeks. In case the patients needed to wear a prosthesis, the prosthesis was relieved with a soft liner to ensure there would be no pressure on the surgical site. Patients were reviewed at 1 week, 2 months, and 4 months to evaluate the augmented sites. Dental implants were placed at 4 months after grafting and the patients were recalled within the next 4 months to check the condition of the implants. The longest follow-up period, to date, was 1 year with the implant functionally healthy with no sign of complication. Clinical examination Measurements of the socket ridge dimensions were performed as follows: (1) Vertical height was measured with a periodontal probe. This measurement evaluated the distance between the occlusal table of the tooth adjacent to the alveolar crest of the extraction socket using 4 landmarks: mesial, midbuccal, distal, and midlingual or midpalatal. (2) Horizontal width measurement with bone mapping forceps or using ridge mapping technique at 2 points: 3 and 8 mm apical to the cemento-enamel junction (CEJ) of the adjacent tooth. Each measurement was done twice and the average
OOOOE Volume 110, Number 5
value was recorded. Additionally, an intraoperational standardization was conducted to reduce measurement error. The measurements were done 3 times separately: before extraction, after ridge preservation surgery, and before ridge exposure for implant placement at 4 months after ridge preservation. Radiographic measurement After the radiograph was taken, the film was digitized. The radiographic data from each patient were collected in a series from immediately postsurgery until the reentry visit. Radiographic density analysis was performed using ImageProPlus program (Media Cybermetics Inc., Milano, Italy). The density of the grafted socket was averaged from 5 different areas within the socket: coronal, mid socket, apical, mesial, and distal side. Also, the density of the surrounding host bone was derived from 5 different areas apical to the root apex. These 2 average values were then transformed into a percentage using the radiodensity of the cementum of the adjacent tooth as a reference point. The derived percentage of the grafted socket was normalized to that of the host bone to generate a final radiodensity percentage. The final percentage was used to determine the overall socket radiographic density alteration over the 4-month healing period. Histological and histomorphometric analysis of the bone biopsy Local anesthesia was administered and full mucoperiosteal buccal and lingual flaps were reflected. As part of the implant site preparation, a surgical trephine bur with a 2-mm inner diameter and 6-mm length was used to harvest a 6 ⫻ 2-mm cylindrical bone core from the central part of the former sockets. The ridge bone was prepared to receive an appropriate-sized endosseous implant having a minimum length of 10 mm. At the time of the implant placement, the degree of graft consolidation was also observed and then recorded. The primary stability of the implant was assessed by using a torque control rachet. The bone specimens were fixed immediately in 10% neutral buffered formalin. The specimens were dehydrated in a series of graded alcohols, and placed in xylene. Specimens were embedded in paraffin and serial sections taken at 5- thickness. Selected sections were stained with hematoxylin-eosin (HE) and slides labeled with the patient number. Each section was evaluated histologically and quantitatively analyzed under light microscopy at ⫻10 and ⫻100 magnification for total biopsy area, total bone area, and residual graft particle area. Finally, the percentage of new bone for-
Kesmas et al. e27
mation, connective tissue, and residual graft particles was calculated. The immunohistochemical staining of osteopontin Paraffin-embedded undecalcified specimens cut at a thickness of 5 were placed on poly-L-lysine slides. All sections were routinely deparaffinized in xylene and rehydrated through a series of graded alcohol. Osteopontin (OPN) antigens in the specimens were retrieved in a citrate buffer (pH 6.0) in a pressure cooker. Endogenous peroxidase was inactivated by incubating the slides with 2% hydrogen peroxide in methanol for 10 minutes and then with 5% bovine serum albumin (BSA) for 10 minutes. For detection of OPN, mouse antihuman OPN monoclonal antibody clone AKm2A1 (Santa Cruz Biotechnology, Inc., Santa Cruz, CA) at a dilution of 1:100 was used as a primary antibody with incubation at 4°C in a moist chamber for 24 hours. After washing with Tris-buffered saline (TBS), a secondary monoclonal antibody, peroxidase-conjugated goat antimouse immunoglobulin (Dako North America, Inc., Carpinteria, CA), was applied. Diaminobenzidine solution (DAB solution) was added to detect chromogenesis. Cell nuclei were counterstained with hematoxylin and enhanced with Scott’s tap water. Thereafter, the slides were coverslipped using mounting media. Staining was assessed for OPN expression under light microscope. Statistical analysis The differences from baseline and the reentry visit data were identified by the Wilcoxon Signed-Rank test (Statistical Package for the Social Sciences [SPSS] for Windows version 16.0; SPSS, Inc., Chicago, IL). A P value of .05 or less was considered to be statistically significant. RESULTS Eight subjects (3 males and 5 females) between 25 and 57 years old (mean age 46.5 ⫾ 10.2 years) were included in this study. Each patient was treated at one nonmolar site by ridge preservation surgery and subsequently received a dental implant except for one patient who decided to receive a fixed prosthesis. All of the extracted teeth were maxillary central incisors and judged hopeless, mostly because of tooth fracture after endodontic treatment. The surrounding gingival soft tissue exhibited mild inflammation without recession in 7 of 8 cases. One case presented with a fistula opening at the labial gingiva. At the time of extraction, none of the sites had acute or active infection with suppuration. Most of the sites had a mild to moderate amount of granulation tissue, which did not contradict the application of this synthetic BCP bone-grafting material.
e28
Kesmas et al.
OOOOE November 2010
Fig. 3. a-f, Ridge preservation procedure at site 11 (patient 1). a, b, Labial and occlusal views of fractured tooth no. 11. c, d, Labial and occlusal views after ridge preservation with biphasic calcium phosphate and a resorbable collagen membrane was performed. The grafted socket was covered with a collagen wound dressing material. e, f, Radiographs before and after ridge preservation.
The postoperative healing of all sites by secondary intention was uneventful without any signs of infection or prominent inflammatory response. After a 4-month healing period, all sites maintained good and satisfactory bone and soft tissue contours. In almost all of the augmented sites (7/8), graft consolidation was evident but the grafted generated bone was distinguishable from the surrounding host bone (Figs. 3-5). In one patient, graft particles were not entirely consolidated and remained as granules; therefore, it was decided to extend the healing period to 8 months. However, because of the availability of this patient, the second reentry was performed at 10 months. The grafted socket of this patient had healed normally by this time. Dental implants (Straumann BoneLevel implants; Institut Straumann AG, Basel, Switzerland)
were placed in all augmented sites achieving initial stability with an insertion torque 20-35 Ncm. Because of the limited mesio-distal space of the maxillary left central incisor in one patient, a Straumann BoneLevel implant, 3.3 mm in diameter was placed in this patient. Implants with 4.1 mm in diameter were delivered to the remaining patients. Immediately after implant placement, one patient exhibited no exposed implant threads or facial bone defect. The remaining patients evidenced only a few exposed threads, so BCP alone was used for contour augmentation or BCP in combination with a resorbable collagen membrane applied to restore the observed defect. Notably, the resistance to drilling during implant placement preparation and placement was lower than that of native bone likely because of less mature new bone. Seven
OOOOE Volume 110, Number 5
Kesmas et al. e29
Fig. 4. a-g, Implant installation procedure at implant site 11 at 4 months after ridge preservation was performed (patient 1). a, b, Labial and occlusal views of site 11 showing minute vertical ridge resorption. c, The particulate grafts were well consolidated after the 4-month healing period. d, e, Implant could be placed in a prosthetically ideal position. f, Radiograph at 4 months after socket grafting. g, Radiograph after implant placement.
implants were placed in the anterior maxilla following the submerged implant placement protocol and fixed provisional prostheses were inserted at the time of reentry surgery. The second stage implant surgery was performed after 4 months of osseointegration and subsequently a prosthesis was delivered. No implant mobility or any implant-associated complications were found during this period.
Vertical alveolar ridge height changes The primary ridge height loss occurred in the midbuccal side of the socket (⫺1.5 mm). The amount of reduction was minimal on the mesial and distal sides of the socket. Notably, no vertical loss was found in the midpalatal side. However, there were no statistically significant differences observed in the median change from baseline to reentry data (Table II).
Horizontal alveolar ridge width changes When comparing baseline and 4-month reentry values, a reduction of ridge width was found 3 mm from the CEJ. The median value of reduction of 2 mm was statistically significant when compared with the preextraction width. An increase in ridge width was noted at 8 mm from the CEJ; however, this amount (1 mm) was minor and not statistically significant (Table I).
Histological and immunohistochemical evaluation Specimens for histological examination were obtained from 6 of 8 patients. The biopsy of Patient 5 was unable to be obtained, as the regenerated bone was relatively soft and unrecoverable. Patient 8 decided to receive a fixed prosthesis instead of implant-supported prosthesis. Thus, a total of 6 biopsies were sent for histological study: 5 biopsies were evaluated at 4
e30
Kesmas et al.
OOOOE November 2010
Fig. 5. a-k, Clinical photograph of site 11 (patient 3). a, b, Labial and occlusal views of fractured root no. 11. c, d, Labial and occlusal views of no. 11 at 4 months after grafting. e, Four months after ridge preservation, the graft was well consolidated. f, g, Implant could be placed in a prosthetically ideal position; however, bone augmentation was performed at the 1- to 2-mm bony dehiscence. h-k, Radiographs at preoperation, immediately after grafting, 4 months after grafting and implant installation.
OOOOE Volume 110, Number 5
Kesmas et al. e31
Table I. Horizontal alveolar ridge width changes in mm (median value) Treatment
Measurement
Initial
Reentry
Changes
BCP⫹GBR
Width at 3 mm from CEJ Width at 8 mm from CEJ
6.0
3.75
⫺2.0*
6.5
7.00
⫹1.0
BCP, biphasic calcium phosphate; GBR, guided bone regeneration with a resorbable collagen membrane; CEJ, cemento-enamel junction; ⫹, bone gain; ⫺, bone loss. *P ⬍ .05 between initial and reentry (4 months postextraction) values.
Table II. Vertical alveolar ridge height changes in mm (median value) Treatment
Measurement
Initial
Reentry
Changes
BCP⫹GBR
Mesial Midbuccal Midpalatal Distal
11.0 14.5 12.5 10.0
10.0 13.0 11.5 9.5
⫺1.0 ⫺1.5 0 ⫺0.5
Fig. 6. Histological feature of biopsy harvesting from patient 1. Notably, the main component of the specimen is a wellarranged lamellar bone with bone marrow (⫻20 magnification, H&E stain).
BCP, biphasic calcium phosphate; GBR, guided bone regeneration with a resorbable collagen membrane; ⫹, bone gain; ⫺, bone loss.
months and 1 at 10 months after the ridge preservation surgery had been performed. Histologically, BCP particles did not stain with HE and were easily distinguished from neighboring bone and connective tissue. New bone formation was observed in 4 biopsies. A wide range in the quantity of new bone formation was noted (Figs. 6 and 7). The specimen from Patient 1 expressed classic features of bone tissue consisting of mature lamellar bone with well-arranged Haversian systems (Fig. 6). Osteocytes encased within the lacuna were also observed. This biopsy contained a few graft particles remaining in contact with the fibrous connective tissue. In contrast, biopsies from Patients 3, 4, and 6 revealed few areas of bone; for instance, islands of bone spicules or areas of osteoid formation (Fig. 7). These specimens had an abundant amount of connective tissue and unresorbed residual graft particles. There was no new bone formation demonstrated in 2 biopsies. In these, osteoclastic activity was apparent, with osteoclasts lying within Howship’s lacunae in the fibrous connective tissue stroma adjacent to the graft remnants. The remaining graft particles were generally mixed throughout the connective tissue. Numerous new blood vessels and chronic inflammatory cells were visible in some histological fields of these biopsies. Histomorphometric analysis revealed the principal component in 5 of 6 biopsies was connective tissue (15%-87%). New bone formation comprised between
Fig. 7. Histological feature of biopsy harvesting from patient 3. The sample was primarily composed of connective tissue (CT) whereas residual graft particles (G) were the second component. The vital bone was merely a woven bone composed of osteoid matrix (B) (⫻20 magnification, H&E stain).
7% and 83%, whereas graft particles were the smallest component (2%-26%). The greatest new bone formation was detected in Patient 1, with a small amount of connective tissue and graft particle remnants at 83%, 15%, and 2%, respectively (Fig. 5). The mean percentage of new bone formation, connective tissue, and residual graft particles in all samples were 28.00% ⫾ 36.75%, 65.50% ⫾ 25.85%, and 15.83% ⫾ 8.70%, respectively. Immunological study of patients’ biopsies
e32
Kesmas et al.
Fig. 8. Photomicrograph showed an immunohistochemical staining of OPN section from patient 3. The sample contained the dark-staining cells indicating the OPN expression of these cells, which were embedded in the connective tissue stroma. These cells were osteoblast-like cells (arrows) (⫻20 magnification).
showed OPN expression in the cytoplasm of most cells distributed within the connective tissue stroma. These OPN-expressing cells can be described as osteoblastlike cells (Fig. 8). Radiographic evaluation Radiographically, BCP particles were seen as radiopaque granules. After applying this bone substitute into the extraction socket, the socket exhibited greater radiopacity than the surrounding host bone (data not shown). Compared to the density of the cementum of the adjacent tooth cementum, the density of the sockets immediately after grafting and 4 months after grafting was lower than that of the neighboring host bone (Table III). Eventually, the percentage of the grafted socket was normalized to the percentage of the host bone to generate a final radiodensity percentage. As shown in Table III, the density of the grafted socket tended to decrease during the 4-month healing period when measured as a percentage of native host bone in all of the patients. In Patient 2 (10-month healing period), the density of the grafted socket reduced gradually from 4 months, 8 months, and finally 10 months (100.50%, 82.82%, and 80.21%, respectively). The median change in radiographic density of –11.42% was statistically significant (P ⬍ .05). The data are shown in Table IV. DISCUSSION This 4-month clinical study evaluated the quality and quantity of bone regenerated using a ridge preservation technique performed with BCP combined with a resorbable collagen membrane in the anterior maxillary
OOOOE November 2010
region. Data from prior studies had shown significant alveolar bone volume reduction as a result of bone resorption after tooth loss. Approximately two thirds of this loss occurred in the first 3 months with a loss of up to 50% of alveolar ridge volume over a 12-month period.1,3 In the present study, a median reduction of 2 mm ridge width at 3 mm apical to the CEJ of the adjacent teeth was observed. This may the result of the normal healing process of alveolar bone.1,3,4 However, this loss was found to be statistically significant. Dehiscence or defects of the labial plate are common after tooth extraction, particularly in the anterior maxilla owing to the thin and frail bone of labial plate. This clinical presentation was required for inclusion in this study. The labial crest defect could have been responsible for the significant ridge width reduction. The amount of ridge width reduction uncovered in this present study was lower than normal ridge resorption of 4.9 mm after tooth extraction.23 The reduction of horizontal ridge width found in this study is corroborated by other ridge preservation studies using different osseous grafting materials and/or membranes. These investigations revealed mean horizontal ridge changes ranging from 0.65 to 4.50 mm.2,24-30 A study on ridge preservation performed with BCP found less resorption of the grafted sites as compared with the naturally healed sites. However, the authors observed only the clinical change of the alveolar ridge; no ridge measurement method was conducted.31 Thus, direct comparisons to our work cannot be made. Results from studies, including the present study, found ridge preservation procedures alone cannot entirely maintain the original width of the alveolar ridge. Simon et al.26 suggested an additional GBR overlaid on the buccal and coronal portion of the alveolar bone could help preserved or even slightly augmented the original contour. This suggests a simple intrasocket graft performed in ridge preservation may be inadequate to preserve the baseline contour of the alveolar bone, especially in the maxillary anterior where esthetics are of high concern, so an additional extrasocket overlay graft might be needed. Ridge height loss measured from 4 crestal bone areas around the socket opening was greatest at the midbuccal side. The application of a resorbable collagen membrane to the labial bone partially reduced the vertical alteration. Vertical resorption on other sides including the mesial and distal sides was minimal. An advantage of the ridge preservation procedure is in maintaining the mesial and distal bone height, which is crucial in interdental papilla regeneration at the future implant site especially in areas of high esthetic concern such as the anterior maxilla.32,33 A slight decrease in ridge height from this study was noted compared with pre-
OOOOE Volume 110, Number 5
Kesmas et al. e33
Table III. The comparison of the radiographic density between the grafted socket and the neighboring host bone Immediate postop
1 wk postop
2 mo postop
4 mo postop
Patient
Preop host
Socket
Host
%
Socket
Host
%
Socket
Host
%
Socket
Host
%
1 2 3 4 5 6 7 8
90.89 107.62 104.56 102.17 94.76 77.94 97.93 124.61
95.41 119.01 107.46 102.09 95.81 88.56 90.97 92.39
99.75 93.72 102.88 107.91 105.21 84.59 104.19 131.89
95.65 127.00 104.5 94.61 91.07 104.7 87.31 70.05
89.63 114.79 101.66 — 96.36 77.61 85.41 92.54
119.68 113.92 127.77 — 83.86 80.92 108.52 112.90
74.89 100.80 79.56 — 114.9 95.91 78.70 81.97
81.03 102.48 103.49 88.07 — 86.36 77.08 87.23
132.66 122.34 97.23 101.60 — 86.85 104.36 121.02
61.08 83.77 106.44 86.68 — 99.44 73.86 72.08
71.93 101.83 103.85 94.74 88.66 82.51 80.34 86.66
111.24 101.37 114.95 105.57 97.85 85.92 143.21 129.28
64.66 100.5 90.34 89.74 90.61 96.03 56.10 67.03
Preop, preoperative; postop, postoperative; -, missing data.
Table IV. Radiographic analysis: median percentage of the grafted socket compared with the host bone Treatment
Initial
Reentry
Changes
BCP⫹GBR
95.13
84.98
⫺11.42*
BCP, biphasic calcium phosphate; GBR, guided bone regeneration with a resorbable collagen membrane; —, reduction in radiodensity. *P ⬍ .05 between initial and reentry (4 months postextraction) values.
vious ridge preservation reports.2,24,25,28,30 Iasella et al.27 reported a gain of 1.3 mm ridge height with the use of freeze-dried bone allograft (FDBA) concomitant with collagen membrane for preserving residual ridge contour. However, the vertical dimension on the midpalatal side was preserved. Variations in graft materials and differences in ridge preservation techniques must be considered when judging the present findings against previous studies. Sclar22 claimed ridge preservation performed with a Bio-Col technique could minimize the resorption of alveolar ridge and preserve the soft tissue contours. It could also reduce the need for secondary surgery and attain optimum esthetics with more predictability.34 The Bio-Col technique used bovine bone– derived hydroxyapatite as a graft material filled into the extraction socket. The key difference in this study was the selected bone graft material. BCP (BoneCeramic) is a fully synthetic bone substitute composed of 60% hydroxyapatite and 40% beta-tricalcium phosphate, and thus is not susceptible to any of the drawbacks associated with biological bone substitutes. In our study, histologically, the amount of regenerated bone in the grafted tissue varied with the percentage of newly formed bone between 7% and 83%. Individual variations might be responsible for this wide range, and examination of these reveal some intriguing considerations. Of these 6 specimens, there were 4 specimens
taken from female patients whose ages were in the same range (51-57 years). These 4 female patients were in differing menopausal states, with some receiving hormone therapy. These differences may be reflected in the different rate of healing response after the bonegrafting procedures. The greatest bone formation in Patient 1 may be attributable to her concern in her overall self-care. She had a well-controlled diet including vitamin supplements and regular exercise. Although not completely menopausal, she had been prescribed supplementary calcium for almost 30 years. Two patients (Patients 2 and 7) were also menopausal women without hormone replacement therapy and had a lower bone mass. The important correlation between the amount of calcium intake and bone health status had been well recognized,35,36 although there was no study to point out the effect of calcium supplements on bone graft healing. Erdogan et al.37 had discovered the association between osteoporotic patients and alveolar ridge augmentation. These patients had an increased rate of complications; for instance, resorption of bone graft, nonintegration of bone graft, delayed healing time, and implant failure particularly in the anterior maxilla. This suggests a careful assessment of a patient’s overall bone health/remodeling status should be done with possible alterations in diet suggested before bone regenerative therapies. After the 4-month healing period of this study, the low percentage of residual graft particles detected indicated an appropriate degradation time with good biocompatibility of the material without significant inflammatory response. The amount of residual BCP particles was in the same range as other bone substitutes used for preserving alveolar ridge architecture ranging between 13.5% and 42.0%.27,38,39 The mean BCP remnants of 15.83% ⫾ 8.70% in this study were considerably fewer than found with the use of bovine bone grafts,17,19,22,40 and was significantly lower than the limit set (40%) for acquiring successful implant installation.19
e34
Kesmas et al.
The mean percentage of new bone formation discovered in this study of 28.00% ⫾ 36.75% was in accordance with previous studies of the same material used in sinus augmentation procedures.21,41,42 De Coster et al.31 histologically studied specimens collected from biphasic calcium phosphate–augmented sockets and found the tissue was mainly composed of loosely arranged connective tissue with some mineralized bone. When compared with untreated control sites, the formation of new bone was better than the substituted sites. This result was consistent with the present study. When compared with other ridge preservation studies performed with various bone-grafting materials, the percentage of vital bone from the present study was comparable (range between 26.0% and 68.5%).7,17,19,27-30,43,44 Importantly, an increasing vital bone volume had been disclosed in a BCP augmented sinus from 6 to 8 months. This finding implies that in a BCP augmented site, a longer healing period is beneficial for new bone formation and for additional graft consolidation.41 Other previous studies in animal and human models reported the healing of defects grafted with BCP with persistence of this grafting material at 8 to 9 months following the grafting procedure.31,45,46 These findings were in line with the observations from this study. Incomplete graft consolidation discovered at the 4-month time point suggest an extended healing time of 6 to 8 months before implant placement for superior graft consolidation. Studies using Bio-Oss also observed this xenograft in the grafted site after a 4-month healing period. The implant insertion torque at this grafted site was less than 25 Ncm and the recommended healing time of this type of grafting material was at least 6 to 9 months.47,48 When focusing on the amount of residual graft particles, BCP particles apparently degraded in a shorter period of time, which could have a positive effect on new osseous regeneration. To our knowledge, our study is one of the initial reports of BCP used as bone graft filler in a fresh extraction socket; therefore, there are no studies that strongly validate this assumption. In our study, almost all of the examined biopsies had connective tissue as a predominant component of the specimen. Although the main component was connective tissue, the observation from immunohistochemical staining for OPN indicated the osteogenic potential of the cells embedded within the connective tissue stroma. Osteopontin has been implicated as an important factor in bone remodeling.49 After osteoblastic cell differentiation and maturation, these cells should promote more osseous regeneration over a longer healing time. Thus far, there have been no reports on the expression of bone markers such as OPN in the tissue subsequent to socket augmentation. Our data indicate OPN expres-
OOOOE November 2010
sion can be used in characterizing cells in the augmentation site as having an osteoblastic phenotype. In this study, the radiodensity of the grafted sockets was also evaluated. The BCP grafting material was a radiopaque particle that could be discriminated from the surrounding host bone after application into the extraction socket with a higher density when compared with the host bone. At implant placement, the average density of the grafted socket was lower than that of the host bone. The density of the grafted socket was lower likely because it consisted of several nonmineralized components such as osteoid matrix, fibrous connective tissue, and grafting material. On the other hand, the only component of the neighboring host bone was mature bone with some marrow spaces, which should result in a higher radiodensity. In Patient 2, the healing period was prolonged to 10 months because of poor graft consolidation. The radiodensity of the grafted socket immediately after grafting was much greater than the surrounding host bone. This could suggest that overpacking of the graft might hinder bone graft healing and new bone regeneration by obstructing the revascularization of the vessels.42 In this study, the healing time was limited to 4 months because the purpose of this study was to determine the effectiveness of the selected grafting material over this shorter healing period. However, a longer follow-up period to assess the alteration of radiodensity of the grafted socket is necessary to determine the influence of the material on new bone formation, and studies of radiographic healing of the BCP grafting sites are required to draw any conclusion from the present findings. In our study, the longest follow-up period after prosthetic delivery was almost 12 months. There was no implant-associated complication such as pain, abscess, implant mobility, or loss of implant. No signs of peri-implant mucositis or peri-implantitis were observed. Importantly, the surrounding bone crest was preserved to the level of implant platform without any signs of bone resorption. CONCLUSION The preliminary clinical and histological investigations from this ridge preservation study using BCP in conjunction with a resorbable collagen membrane displayed an encouraging result in preserving alveolar ridge dimension after tooth loss. Moderate vital bone formation could be achieved after a 4-month healing period and tended to increase over time likely by OPN-expressing cells. The amount of unresorbed graft particles were acceptable for implant delivery. Thus, BCP was advantageous in preserving ridge dimension from a clinical perspective. By radio-
OOOOE Volume 110, Number 5
graphic analysis, the appropriate healing time could be judged by observing the decline of the radiodensity of the grafted socket. We show ridge preservation with BCP and a resorbable collagen membrane is useful in maintaining ridge dimension after tooth extraction and reduces the need for future ridge augmentation before dental implant placement. UNCITED REFERENCES This section consists of references that are included in the reference list but are not cited in the article text. Please either cite each of these references in the text or, alternatively, delete it from the reference list. If you do not provide further instruction for this reference, we will retain it in its current form and publish it as an “un-cited reference” with your article.46,47 This section consists of references that are cited in the article text but are not included in the reference list. Please either add each of these references to the reference list or, alternatively, delete it from the text. If you do not provide further instruction for this reference, we will retain it in its current form and publish it as an “un-cited reference” with your article.50 REFERENCES 1. Pietrokovski J, Massler M. Alveolar ridge resorption following tooth extraction. J Prosthet Dent 1967;17:21-7. 2. Lekovic V, Kenney EB, Weinlaender M, Han T, Klokkevold P, Nedic M, et al. A bone regenerative approach to alveolar ridge maintenance following tooth extraction. Report of 10 cases. J Periodontol 1997;68:563-70. 3. Schropp L, Kostopoulos L, Wenzel A. Bone healing following immediate versus delayed placement of titanium implants into extraction sockets: a prospective clinical study. Int J Oral Maxillofac Implants 2003;18:189-99. 4. Werbitt MJ, Goldberg PV. The immediate implant: bone preservation and bone regeneration. Int J Periodontics Restorative Dent 1992;12:206-17. 5. Fowler EB, Breault LG, Rebitski G. Ridge preservation utilizing an acellular dermal allograft and demineralized freeze-dried bone allograft: Part II. Immediate endosseous implant placement. J Periodontol 2000;71:1360-4. 6. Bartee BK. Extraction site reconstruction for alveolar ridge preservation. Part 1: rationale and materials selection. J Oral Implantol 2001;27:187-93. 7. Froum S, Cho SC, Rosenberg E, Rohrer M, Tarnow D. Histological comparison of healing extraction sockets implanted with bioactive glass or demineralized freeze-dried bone allograft: a pilot study. J Periodontol 2002;73:94-102. 8. Block MS. Treatment of the single tooth extraction site. Oral Maxillofac Surg Clin North Am 2004;16:41-63. 9. Reddi AH, Wientroub S, Muthukumaran N. Biologic principles of bone induction. Orthop Clin North Am 1987;18:207-12. 10. Schwartz Z, Mellonig JT, Carnes DL Jr, de la Fontaine J, Cochran DL, Dean DD, et al. Ability of commercial demineralized freeze-dried bone allograft to induce new bone formation. J Periodontol 1996;67:918-26. 11. Zhang M, Powers RMJ, Wolfinbarger LJ. A quantitative assessment of osteoinductivity of human demineralized bone matrix. J Periodontol 1997;68:1076-84.
Kesmas et al. e35 12. Becker W, Urist MR, Tucker LM, Becker BE, Ochsenbein C. Human demineralized freeze-dried bone: inadequate induced bone formation in athymic mice. A preliminary report. J Periodontol 1995;66:822-8. 13. Buser D, Hoffmann B, Bernard JP, Lussi A, Mettler D, Schenk RK. Evaluation of filling materials in membrane-protected bone defects. A comparative histomorphometric study in the mandible of miniature pigs. Clin Oral Implants Res 1998;9:137-50. 14. Hammerle CH, Chiantella GC, Karring T, Lang NP. The effect of a deproteinized bovine bone mineral on bone regeneration around titanium dental implants. Clin Oral Implants Res 1998;9:151-62. 15. Artzi Z, Nemcovsky CE. The application of deproteinized bovine bone mineral for ridge preservation prior to implantation. Clinical and histological observations in a case report. J Periodontol 1998;69:1062-7. 16. Artzi Z, Dayan D, Alpern Y, Nemcovsky CE. Vertical ridge augmentation using xenogenic material supported by a configured titanium mesh: clinicohistopathologic and histochemical study. Int J Oral Maxillofac Implants 2003;18:440-6. 17. Artzi Z, Tal H, Dayan D. Porous bovine bone mineral in healing of human extraction sockets. Part 1: histomorphometric evaluations at 9 months. J Periodontol 2000;71:1015-23. 18. Artzi Z, Tal H, Dayan D. Porous bovine bone mineral in healing of human extraction sockets: 2. Histochemical observations at 9 months. J Periodontol 2001;72:152-9. 19. Carmagnola D, Adriaens P, Berglundh T. Healing of human extraction sockets filled with Bio-Oss. Clin Oral Implants Res 2003;14:137-43. 20. Piattelli A, Scarano A, Mangano C. Clinical and histologic aspects of biphasic calcium phosphate ceramic (BCP) used in connection with implant placement. Biomaterials 1996;17:1767-70. 21. Cordaro L, Bosshardt DD, Palattella P, Rao W, Serino G, Chiapasco M. Maxillary sinus grafting with Bio-Oss or Straumann Bone Ceramic: histomorphometric results from a randomized controlled multicenter clinical trial. Clin Oral Implants Res 2008;19:796-803. 22. Sclar AG. Preserving alveolar ridge anatomy following tooth removal in conjunction with immediate implant placement. The Bio-Col technique. Atlas Oral Maxillofac Surg Clin North Am 1999;7:39-59. 23. Schropp L, Wenzel A, Kostopoulos L, Karring T. Bone healing and soft tissue contour changes following single-tooth extraction: a clinical and radiographic 12-month prospective study. Int J Periodontics Restorative Dent 2003;23:313-23. 24. Lekovic V, Camargo PM, Klokkevold PR, Weinlaender M, Kenney EB, Dimitrijevic B, et al. Preservation of alveolar bone in extraction sockets using bioabsorbable membranes. J Periodontol 1998;69:1044-9. 25. Camargo PM, Lekovic V, Weinlaender M, Klokkevold PR, Kenney EB, Dimitrijevic B, et al. Influence of bioactive glass on changes in alveolar process dimensions after exodontia. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2000;90:581-6. 26. Simon BI, Von Hagen S, Deasy MJ, Faldu M, Resnansky D. Changes in alveolar bone height and width following ridge augmentation using bone graft and membranes. J Periodontol 2000;71:1774-91. 27. Iasella JM, Greenwell H, Miller RL, Hill M, Drisko C, Bohra AA, et al. Ridge preservation with freeze-dried bone allograft and a collagen membrane compared to extraction alone for implant site development: a clinical and histologic study in humans. J Periodontol 2003;74:990-9. 28. Vance GS, Greenwell H, Miller RL, Hill M, Johnston H, Scheetz JP. Comparison of an allograft in an experimental putty carrier and a bovine-derived xenograft used in ridge preservation: a
e36
29.
30.
31.
32.
33.
34. 35. 36. 37.
38.
39.
40.
41.
OOOOE November 2010
Kesmas et al.
clinical and histologic study in humans. Int J Oral Maxillofac Implants 2004;19:491-7. Neiva RF, Tsao YP, Eber R, Shotwell J, Billy E, Wang HL. Effects of a putty-form hydroxyapatite matrix combined with the synthetic cell-binding peptide P-15 on alveolar ridge preservation. J Periodontol 2008;79:291-9. Barone A, Aldini NN, Fini M, Giardino R, Calvo Guirado JL, Covani U. Xenograft versus extraction alone for ridge preservation after tooth removal: a clinical and histomorphometric study. J Periodontol 2008;79:1370-7. De Coster P, Browaeys H, De Bruyn H. Healing of extraction sockets filled with BoneCeramic(R) prior to implant placement: preliminary histological findings. Clin Implant Dent Relat Res 2009 [Epub ahead of print]. Tarnow DP, Magner AW, Fletcher P. The effect of the distance from the contact point to the crest of bone on the presence or absence of the interproximal dental papilla. J Periodontol 1992;63:995-6. Tarnow DP, Cho SC, Wallace SS. The effect of inter-implant distance on the height of inter-implant bone crest. J Periodontol 2000;71:546-9. Sclar A. Soft tissue and esthetic considerations in implant therapy. Chicago: Quintessence; 2003. Heaney RP. Ethnicity, bone status, and the calcium requirement. Nutr Res 2002;22:153-78. Heaney RP. The importance of calcium intake for lifelong skeletal health. Calcif Tissue Int 2002;70:70-3. Erdogan O, Shafer DM, Taxel P, Freilich MA. A review of the association between osteoporosis and alveolar ridge augmentation. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2007;104:738.e1-738.e13. Froum S, Cho SC, Elian N, Rosenberg E, Rohrer M, Tarnow D. Extraction sockets and implantation of hydroxyapatites with membrane barriers: a histologic study. Implant Dent 2004;13: 153-64. Luczyszyn SM, Papalexiou V, Novaes AB Jr, Grisi MF, Souza SL, Taba M Jr. Acellular dermal matrix and hydroxyapatite in prevention of ridge deformities after tooth extraction. Implant Dent 2005;14:176-84. Cardaropoli D, Cardaropoli G. Preservation of the postextraction alveolar ridge: a clinical and histologic study. Int J Periodontics Restorative Dent 2008;28:469-77. Froum SJ, Wallace SS, Cho SC, Elian N, Tarnow DP. Histo-
42.
43.
44.
45.
46.
47.
48.
49.
morphometric comparison of a biphasic bone ceramic to anorganic bovine bone for sinus augmentation: 6- to 8-month postsurgical assessment of vital bone formation. A pilot study. Int J Periodontics Restorative Dent 2008;28:273-81. Friedmann A, Dard M, Kleber BM, Bernimoulin JP, Bosshardt DD. Ridge augmentation and maxillary sinus grafting with a biphasic calcium phosphate: histologic and histomorphometric observations. Clin Oral Implants Res 2009;20:708-14. Serino G, Biancu S, Iezzi G, Piattelli A. Ridge preservation following tooth extraction using a polylactide and polyglycolide sponge as space filler: a clinical and histological study in humans. Clin Oral Implants Res 2003;14:651-8. Wang HL, Tsao YP. Histologic evaluation of socket augmentation with mineralized human allograft. Int J Periodontics Restorative Dent 2008;28:231-7. Jensen SS, Yeo A, Dard M, Hunziker E, Schenk R, Buser D. Evaluation of a novel biphasic calcium phosphate in standardized bone defects: a histologic and histomorphometric study in the mandibles of minipigs. Clin Oral Implants Res 2007;18:752-60. Sculean A, Windisch P, Szendroi-Kiss D, Horvath A, Rosta P, Becker J, et al. Clinical and histologic evaluation of an enamel matrix derivative combined with a biphasic calcium phosphate for the treatment of human intrabony periodontal defects. J Periodontol 2008;79:1991-9. Block MS, Finger I, Lytle R. Human mineralized bone in extraction sites before implant placement: preliminary results. J Am Dent Assoc 2002;133:1631-8. Block MS, Jackson WC. Techniques for grafting the extraction site in preparation for dental implant placement. Atlas Oral Maxillofacial Surg Clin N Am 2006;14:1-25. Sodek J, Ganss B, McKee M. Osteopontin. Crit Rev Oral Biol Med 2000;11:279-303.
Reprint requests: Pornchai Jansisyanont, DDS, MS Department of Oral and Maxillofacial Surgery Faculty of Dentistry Chulalongkorn University 34 Henri-Dunant Rd. Patumwan Bangkok 10330, Thailand [email protected]
Objective. The objective of this study was to evaluate clinically, histologically and radiographically a ridge preservation technique used on extraction sockets grafted with biphasic calcium phosphate (BCP) and a resorbable collagen membrane. Material and methods. Patients having a labial socket wall defect more than one-third in mesio-distal socket width after maxillary central incisor tooth extraction were included. The labial defect was sealed with resorbable collagen membrane and the defect filled with BCP. The grafted socket was covered with a resorbable collagen wound dressing material. The treated sockets were evaluated after a 4-month healing period when implants were placed and followed for up to 12 months. Results. There were 8 subjects enrolled in this study. A statistical difference was found only in ridge width reduction at 3 mm below the cement-enamel junction of the adjacent teeth (P ⬍ .05) with 1 mm widening at 8 mm. The amount of new bone formation was extensively varied with diminutive graft remnants. Most cells in the connective tissue were osteopontin positive indicating they were osteoblast-like cells. A declination in the radiodensity of the grafted socket was observed during the analyzed period. Conclusion. Ridge preservation with BCP with collagen membrane can be used as an alternative treatment for maintaining ridge dimension before implant placement. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010; 110:e24-e36)
Currently, oral rehabilitation with dental implants is increasing owing to their predictable outcome. Adequate alveolar ridge dimension is required for ideal implant positioning, resulting in proper function and improved esthetics in dental rehabilitation. Unfortunately, consequent to tooth loss, resorption of alveolar This study was supported by a grant from the Chulalongkorn University graduate scholarship to commemorate the 72nd anniversary of His Majesty King Bhumibol Adulyadej and a grant from the 90th Anniversary Chulalongkorn University Fund (Ratchadaphiseksomphot Endowment Fund), Chulalongkorn University, Bangkok, Thailand. The bone graft materials (BCP) were provided by Institut Straumann AG, Basel, Switzerland. a Graduate dental student, Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand. b Associate Professor, Department of Oral Pathology, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand. c Technician, Department of Oral Pathology, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand. d Associate Professor, Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand. e Assistant Professor, Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand. Received for publication Feb 23, 2010; returned for revision May 29, 2010; accepted for publication Jun 9, 2010. 1079-2104/$ - see front matter © 2010 Published by Mosby, Inc. doi:10.1016/j.tripleo.2010.06.006
e24
bone occurs as a result of physiologic healing.1 The pattern of resorption often results in a residual knife edge and a palatally or lingually shifted ridge apex, and a frail and thin labial cortex.1-3 The estimated structural loss is about 40% and 60% of preextraction alveolar ridge height and width, respectively.4 This loss has a detrimental effect on potential treatment with a dental implant or conventional prosthesis. Various techniques have been used to overcome these problems. Augmentation of the extraction socket has been used to maintain or enhance the dimensions of the alveolar bone and soft tissue based on the principle of guided bone regeneration (GBR).5-7 This procedure, also called socket augmentation or ridge preservation, can be performed using multiple types of bone graft including autogenous, allogenous, xenogenous, and alloplastic bone in combination with or without a barrier membrane. Autogenous bone is recognized to be the current “gold standard” of bone grafting material because of the viability of transferable osteogenic cells within the graft but the disadvantages of second donor site morbidity and patient discomfort have led to a decline in the popularity of this material.8 Allografts have demonstrated their osteoinductive potential9-11; however, some studies have failed to show the clinical significance of this potential.12,13 Furthermore, the un-
OOOOE Volume 110, Number 5
certain immune response and risk of disease transmission remain major problems in the clinical use of materials of this type. Recently, the use of xenografts, especially bovine bone has increased not only in ridge preservation procedures, but also other bone augmentation procedures. The important benefits of xenograft bone are a reduction of the drawbacks associated with autografts and their unlimited availability. Some studies have found that bovine bone– grafted sites demonstrated a better outcome and indicated this material could be a good bone substitute for bone augmentation before implant installation.14-16 Downsides of the use of bovine bone include its slowly resorbability and healing with fibrous encapsulation.17-19 A newly invented synthetic bone substitute composed of 60% hydroxyapatite and 40% beta-tricalcium phosphate (biphasic calcium phosphate [BCP] BoneCeramic; Straumann, Basel, Switzerland) has been introduced for use in preparing surgical sites before implant placement, and in sinus lift procedure, bone augmentation procedures, periodontal surgery, and ridge preservation procedures.20,21 This material provokes bone regeneration by its osteoconductive capacity. Beta-tricalcium phosphate, in the rapid resorption phase, can be completely resorbed and replaced by regenerative bone. This provides for faster bone remodeling. Hydroxyapatite, which is slowly resorbed, serves as a good matrix scaffold for new bone formation. This grafting material has a greater capacity than xenograft bone in enhancing new bone regeneration and can be utterly resorbed and subsequently replaced by host bone in a shorter time. However, there is a paucity of studies confirming the effectiveness of this material in preserving ridge dimension both clinically and histologically. Therefore, the purpose of this study was to clinically, histologically, and radiographically evaluate the healing of extraction sockets treated with BCP combined with a resorbable collagen membrane used as a ridge preservation technique to determine if this bone graft material might be suitable to use given that it does not suffer from the drawbacks of other bone substitutes such as autografts and allografts. MATERIAL AND METHODS Patient selection The study was designed as a prospective study with one treatment group. The study protocol was approved by the Ethics Committee of the Faculty of Dentistry, Chulalongkorn University, Bangkok, Thailand. Before enrollment in this study, all participants signed a written consent form. Patients requiring at least one upper incisor tooth to be extracted and subsequently restored with implant therapy were enrolled in this study. All procedures were carried out in the Department of Oral
Kesmas et al. e25
Fig. 1. Illustration of the socket labial bone defect that was more than one third in mesio-distal width of the socket.
and Maxillofacial Surgery, Faculty of Dentistry, Chulalongkorn University, from October 2007 to October 2009. The reasons for tooth extraction were periodontal disease, endodontic failure, advanced unrestorable caries, or tooth fracture, the diagnosis of which was confirmed by clinical and radiographic examination. The inclusion criteria were systemically healthy patients without any medically compromising conditions, and not taking any medications that would influence their ability to undergo the operation under local anesthesia or alter the healing of the bone and soft tissue. Patients were nonsmokers or previous smokers who had stopped smoking for at least 6 months. Patients with any active infection or those who could not participate through to the end of the study were excluded from the study. The extraction sockets recruited in this study required a defect of the labial bone of more than one third in mesio-distal socket width (Fig. 1). In cases where the labial socket wall was thin (bone thickness less than 1 mm) or had the defect of less than one third in mesiodistal width, the patient was excluded from the study because these clinical presentations do not indicate membrane-assisted socket grafting procedures. The treatment flow-chart is shown in Fig. 2. Evaluation of the present ridge preservation procedure focused on 3 aspects: clinical, histological, and radiographic examination. Operational procedure Preoperatively, a periapical radiograph was taken with parallel technique using an XCP instrument and a customized bite block made from a polyvinyl siloxane impression material for each patient. A 4.0-mm diameter metal ball was inserted into the customized bite
e26
Kesmas et al.
OOOOE November 2010
Fig. 2. Guideline of the treatment provided after the tooth was extracted according to the characteristic of the labial socket bone wall.
block as a radiodensity reference. Chlorhexidine gluconate, 0.2%, mouthwash was used for 1 minute and preoperative prophylaxis with amoxicillin 1 g was prescribed 1 hour before the operation. As one patient was allergic to amoxicillin, clindamycin 600 mg was prescribed to this patient. All patients received local anesthesia (2% mepivacaine with 1:100,000 epinephrine) before surgery. The affected tooth was extracted via flapless atraumatic technique. The socket was thoroughly debrided to remove granulation tissue and copiously irrigated with normal saline solution. When hemostasis in the socket was achieved, the socket wall, except the buccal surface, was perforated with a small surgical round bur exposing the marrow allowing bleeding into the socket. Following the Bio-Col technique proposed by Sclar,22 a resorbable collagen membrane, Bio-Gide (Geistlich, Pharma AG, Wolhusen, Switzerland), was inserted into the labial subperiosteal pocket to seal the socket wall defect. The socket was then augmented with BCP. No effort was made to extend the graft beyond the preexisting dimension of the socket. Subsequently, a resorbable collagen wound dressing material, Collaplug (Zimmer Dental, Carlsbad, CA), was placed over the graft to the level of the marginal gingiva to use as a soft tissue matrix. The surgical site was sutured with absorbable suture, Vicryl (Ethicon, Inc., Somerville, NJ), 4-0 with horizontal mattress or figure-of-eight suture to hold the Collaplug in place without the intention of primary closure. Postoperatively, a periapical radiograph was taken immediately as previously described. All the patients
were advised to rinse with 0.2% chlorhexidine gluconate mouthwash, 1 minute, twice daily for 2 weeks. Ibuprofen 400 mg 3 times daily for postoperative pain control and the appropriate antibiotics were prescribed postoperatively according to preoperative antibiotic prophylaxis, either amoxicillin 500 mg or clindamycin 300 mg 3 times daily for 7 days. The patients were advised not to wear any prosthesis at the surgical site during the first 2 weeks. In case the patients needed to wear a prosthesis, the prosthesis was relieved with a soft liner to ensure there would be no pressure on the surgical site. Patients were reviewed at 1 week, 2 months, and 4 months to evaluate the augmented sites. Dental implants were placed at 4 months after grafting and the patients were recalled within the next 4 months to check the condition of the implants. The longest follow-up period, to date, was 1 year with the implant functionally healthy with no sign of complication. Clinical examination Measurements of the socket ridge dimensions were performed as follows: (1) Vertical height was measured with a periodontal probe. This measurement evaluated the distance between the occlusal table of the tooth adjacent to the alveolar crest of the extraction socket using 4 landmarks: mesial, midbuccal, distal, and midlingual or midpalatal. (2) Horizontal width measurement with bone mapping forceps or using ridge mapping technique at 2 points: 3 and 8 mm apical to the cemento-enamel junction (CEJ) of the adjacent tooth. Each measurement was done twice and the average
OOOOE Volume 110, Number 5
value was recorded. Additionally, an intraoperational standardization was conducted to reduce measurement error. The measurements were done 3 times separately: before extraction, after ridge preservation surgery, and before ridge exposure for implant placement at 4 months after ridge preservation. Radiographic measurement After the radiograph was taken, the film was digitized. The radiographic data from each patient were collected in a series from immediately postsurgery until the reentry visit. Radiographic density analysis was performed using ImageProPlus program (Media Cybermetics Inc., Milano, Italy). The density of the grafted socket was averaged from 5 different areas within the socket: coronal, mid socket, apical, mesial, and distal side. Also, the density of the surrounding host bone was derived from 5 different areas apical to the root apex. These 2 average values were then transformed into a percentage using the radiodensity of the cementum of the adjacent tooth as a reference point. The derived percentage of the grafted socket was normalized to that of the host bone to generate a final radiodensity percentage. The final percentage was used to determine the overall socket radiographic density alteration over the 4-month healing period. Histological and histomorphometric analysis of the bone biopsy Local anesthesia was administered and full mucoperiosteal buccal and lingual flaps were reflected. As part of the implant site preparation, a surgical trephine bur with a 2-mm inner diameter and 6-mm length was used to harvest a 6 ⫻ 2-mm cylindrical bone core from the central part of the former sockets. The ridge bone was prepared to receive an appropriate-sized endosseous implant having a minimum length of 10 mm. At the time of the implant placement, the degree of graft consolidation was also observed and then recorded. The primary stability of the implant was assessed by using a torque control rachet. The bone specimens were fixed immediately in 10% neutral buffered formalin. The specimens were dehydrated in a series of graded alcohols, and placed in xylene. Specimens were embedded in paraffin and serial sections taken at 5- thickness. Selected sections were stained with hematoxylin-eosin (HE) and slides labeled with the patient number. Each section was evaluated histologically and quantitatively analyzed under light microscopy at ⫻10 and ⫻100 magnification for total biopsy area, total bone area, and residual graft particle area. Finally, the percentage of new bone for-
Kesmas et al. e27
mation, connective tissue, and residual graft particles was calculated. The immunohistochemical staining of osteopontin Paraffin-embedded undecalcified specimens cut at a thickness of 5 were placed on poly-L-lysine slides. All sections were routinely deparaffinized in xylene and rehydrated through a series of graded alcohol. Osteopontin (OPN) antigens in the specimens were retrieved in a citrate buffer (pH 6.0) in a pressure cooker. Endogenous peroxidase was inactivated by incubating the slides with 2% hydrogen peroxide in methanol for 10 minutes and then with 5% bovine serum albumin (BSA) for 10 minutes. For detection of OPN, mouse antihuman OPN monoclonal antibody clone AKm2A1 (Santa Cruz Biotechnology, Inc., Santa Cruz, CA) at a dilution of 1:100 was used as a primary antibody with incubation at 4°C in a moist chamber for 24 hours. After washing with Tris-buffered saline (TBS), a secondary monoclonal antibody, peroxidase-conjugated goat antimouse immunoglobulin (Dako North America, Inc., Carpinteria, CA), was applied. Diaminobenzidine solution (DAB solution) was added to detect chromogenesis. Cell nuclei were counterstained with hematoxylin and enhanced with Scott’s tap water. Thereafter, the slides were coverslipped using mounting media. Staining was assessed for OPN expression under light microscope. Statistical analysis The differences from baseline and the reentry visit data were identified by the Wilcoxon Signed-Rank test (Statistical Package for the Social Sciences [SPSS] for Windows version 16.0; SPSS, Inc., Chicago, IL). A P value of .05 or less was considered to be statistically significant. RESULTS Eight subjects (3 males and 5 females) between 25 and 57 years old (mean age 46.5 ⫾ 10.2 years) were included in this study. Each patient was treated at one nonmolar site by ridge preservation surgery and subsequently received a dental implant except for one patient who decided to receive a fixed prosthesis. All of the extracted teeth were maxillary central incisors and judged hopeless, mostly because of tooth fracture after endodontic treatment. The surrounding gingival soft tissue exhibited mild inflammation without recession in 7 of 8 cases. One case presented with a fistula opening at the labial gingiva. At the time of extraction, none of the sites had acute or active infection with suppuration. Most of the sites had a mild to moderate amount of granulation tissue, which did not contradict the application of this synthetic BCP bone-grafting material.
e28
Kesmas et al.
OOOOE November 2010
Fig. 3. a-f, Ridge preservation procedure at site 11 (patient 1). a, b, Labial and occlusal views of fractured tooth no. 11. c, d, Labial and occlusal views after ridge preservation with biphasic calcium phosphate and a resorbable collagen membrane was performed. The grafted socket was covered with a collagen wound dressing material. e, f, Radiographs before and after ridge preservation.
The postoperative healing of all sites by secondary intention was uneventful without any signs of infection or prominent inflammatory response. After a 4-month healing period, all sites maintained good and satisfactory bone and soft tissue contours. In almost all of the augmented sites (7/8), graft consolidation was evident but the grafted generated bone was distinguishable from the surrounding host bone (Figs. 3-5). In one patient, graft particles were not entirely consolidated and remained as granules; therefore, it was decided to extend the healing period to 8 months. However, because of the availability of this patient, the second reentry was performed at 10 months. The grafted socket of this patient had healed normally by this time. Dental implants (Straumann BoneLevel implants; Institut Straumann AG, Basel, Switzerland)
were placed in all augmented sites achieving initial stability with an insertion torque 20-35 Ncm. Because of the limited mesio-distal space of the maxillary left central incisor in one patient, a Straumann BoneLevel implant, 3.3 mm in diameter was placed in this patient. Implants with 4.1 mm in diameter were delivered to the remaining patients. Immediately after implant placement, one patient exhibited no exposed implant threads or facial bone defect. The remaining patients evidenced only a few exposed threads, so BCP alone was used for contour augmentation or BCP in combination with a resorbable collagen membrane applied to restore the observed defect. Notably, the resistance to drilling during implant placement preparation and placement was lower than that of native bone likely because of less mature new bone. Seven
OOOOE Volume 110, Number 5
Kesmas et al. e29
Fig. 4. a-g, Implant installation procedure at implant site 11 at 4 months after ridge preservation was performed (patient 1). a, b, Labial and occlusal views of site 11 showing minute vertical ridge resorption. c, The particulate grafts were well consolidated after the 4-month healing period. d, e, Implant could be placed in a prosthetically ideal position. f, Radiograph at 4 months after socket grafting. g, Radiograph after implant placement.
implants were placed in the anterior maxilla following the submerged implant placement protocol and fixed provisional prostheses were inserted at the time of reentry surgery. The second stage implant surgery was performed after 4 months of osseointegration and subsequently a prosthesis was delivered. No implant mobility or any implant-associated complications were found during this period.
Vertical alveolar ridge height changes The primary ridge height loss occurred in the midbuccal side of the socket (⫺1.5 mm). The amount of reduction was minimal on the mesial and distal sides of the socket. Notably, no vertical loss was found in the midpalatal side. However, there were no statistically significant differences observed in the median change from baseline to reentry data (Table II).
Horizontal alveolar ridge width changes When comparing baseline and 4-month reentry values, a reduction of ridge width was found 3 mm from the CEJ. The median value of reduction of 2 mm was statistically significant when compared with the preextraction width. An increase in ridge width was noted at 8 mm from the CEJ; however, this amount (1 mm) was minor and not statistically significant (Table I).
Histological and immunohistochemical evaluation Specimens for histological examination were obtained from 6 of 8 patients. The biopsy of Patient 5 was unable to be obtained, as the regenerated bone was relatively soft and unrecoverable. Patient 8 decided to receive a fixed prosthesis instead of implant-supported prosthesis. Thus, a total of 6 biopsies were sent for histological study: 5 biopsies were evaluated at 4
e30
Kesmas et al.
OOOOE November 2010
Fig. 5. a-k, Clinical photograph of site 11 (patient 3). a, b, Labial and occlusal views of fractured root no. 11. c, d, Labial and occlusal views of no. 11 at 4 months after grafting. e, Four months after ridge preservation, the graft was well consolidated. f, g, Implant could be placed in a prosthetically ideal position; however, bone augmentation was performed at the 1- to 2-mm bony dehiscence. h-k, Radiographs at preoperation, immediately after grafting, 4 months after grafting and implant installation.
OOOOE Volume 110, Number 5
Kesmas et al. e31
Table I. Horizontal alveolar ridge width changes in mm (median value) Treatment
Measurement
Initial
Reentry
Changes
BCP⫹GBR
Width at 3 mm from CEJ Width at 8 mm from CEJ
6.0
3.75
⫺2.0*
6.5
7.00
⫹1.0
BCP, biphasic calcium phosphate; GBR, guided bone regeneration with a resorbable collagen membrane; CEJ, cemento-enamel junction; ⫹, bone gain; ⫺, bone loss. *P ⬍ .05 between initial and reentry (4 months postextraction) values.
Table II. Vertical alveolar ridge height changes in mm (median value) Treatment
Measurement
Initial
Reentry
Changes
BCP⫹GBR
Mesial Midbuccal Midpalatal Distal
11.0 14.5 12.5 10.0
10.0 13.0 11.5 9.5
⫺1.0 ⫺1.5 0 ⫺0.5
Fig. 6. Histological feature of biopsy harvesting from patient 1. Notably, the main component of the specimen is a wellarranged lamellar bone with bone marrow (⫻20 magnification, H&E stain).
BCP, biphasic calcium phosphate; GBR, guided bone regeneration with a resorbable collagen membrane; ⫹, bone gain; ⫺, bone loss.
months and 1 at 10 months after the ridge preservation surgery had been performed. Histologically, BCP particles did not stain with HE and were easily distinguished from neighboring bone and connective tissue. New bone formation was observed in 4 biopsies. A wide range in the quantity of new bone formation was noted (Figs. 6 and 7). The specimen from Patient 1 expressed classic features of bone tissue consisting of mature lamellar bone with well-arranged Haversian systems (Fig. 6). Osteocytes encased within the lacuna were also observed. This biopsy contained a few graft particles remaining in contact with the fibrous connective tissue. In contrast, biopsies from Patients 3, 4, and 6 revealed few areas of bone; for instance, islands of bone spicules or areas of osteoid formation (Fig. 7). These specimens had an abundant amount of connective tissue and unresorbed residual graft particles. There was no new bone formation demonstrated in 2 biopsies. In these, osteoclastic activity was apparent, with osteoclasts lying within Howship’s lacunae in the fibrous connective tissue stroma adjacent to the graft remnants. The remaining graft particles were generally mixed throughout the connective tissue. Numerous new blood vessels and chronic inflammatory cells were visible in some histological fields of these biopsies. Histomorphometric analysis revealed the principal component in 5 of 6 biopsies was connective tissue (15%-87%). New bone formation comprised between
Fig. 7. Histological feature of biopsy harvesting from patient 3. The sample was primarily composed of connective tissue (CT) whereas residual graft particles (G) were the second component. The vital bone was merely a woven bone composed of osteoid matrix (B) (⫻20 magnification, H&E stain).
7% and 83%, whereas graft particles were the smallest component (2%-26%). The greatest new bone formation was detected in Patient 1, with a small amount of connective tissue and graft particle remnants at 83%, 15%, and 2%, respectively (Fig. 5). The mean percentage of new bone formation, connective tissue, and residual graft particles in all samples were 28.00% ⫾ 36.75%, 65.50% ⫾ 25.85%, and 15.83% ⫾ 8.70%, respectively. Immunological study of patients’ biopsies
e32
Kesmas et al.
Fig. 8. Photomicrograph showed an immunohistochemical staining of OPN section from patient 3. The sample contained the dark-staining cells indicating the OPN expression of these cells, which were embedded in the connective tissue stroma. These cells were osteoblast-like cells (arrows) (⫻20 magnification).
showed OPN expression in the cytoplasm of most cells distributed within the connective tissue stroma. These OPN-expressing cells can be described as osteoblastlike cells (Fig. 8). Radiographic evaluation Radiographically, BCP particles were seen as radiopaque granules. After applying this bone substitute into the extraction socket, the socket exhibited greater radiopacity than the surrounding host bone (data not shown). Compared to the density of the cementum of the adjacent tooth cementum, the density of the sockets immediately after grafting and 4 months after grafting was lower than that of the neighboring host bone (Table III). Eventually, the percentage of the grafted socket was normalized to the percentage of the host bone to generate a final radiodensity percentage. As shown in Table III, the density of the grafted socket tended to decrease during the 4-month healing period when measured as a percentage of native host bone in all of the patients. In Patient 2 (10-month healing period), the density of the grafted socket reduced gradually from 4 months, 8 months, and finally 10 months (100.50%, 82.82%, and 80.21%, respectively). The median change in radiographic density of –11.42% was statistically significant (P ⬍ .05). The data are shown in Table IV. DISCUSSION This 4-month clinical study evaluated the quality and quantity of bone regenerated using a ridge preservation technique performed with BCP combined with a resorbable collagen membrane in the anterior maxillary
OOOOE November 2010
region. Data from prior studies had shown significant alveolar bone volume reduction as a result of bone resorption after tooth loss. Approximately two thirds of this loss occurred in the first 3 months with a loss of up to 50% of alveolar ridge volume over a 12-month period.1,3 In the present study, a median reduction of 2 mm ridge width at 3 mm apical to the CEJ of the adjacent teeth was observed. This may the result of the normal healing process of alveolar bone.1,3,4 However, this loss was found to be statistically significant. Dehiscence or defects of the labial plate are common after tooth extraction, particularly in the anterior maxilla owing to the thin and frail bone of labial plate. This clinical presentation was required for inclusion in this study. The labial crest defect could have been responsible for the significant ridge width reduction. The amount of ridge width reduction uncovered in this present study was lower than normal ridge resorption of 4.9 mm after tooth extraction.23 The reduction of horizontal ridge width found in this study is corroborated by other ridge preservation studies using different osseous grafting materials and/or membranes. These investigations revealed mean horizontal ridge changes ranging from 0.65 to 4.50 mm.2,24-30 A study on ridge preservation performed with BCP found less resorption of the grafted sites as compared with the naturally healed sites. However, the authors observed only the clinical change of the alveolar ridge; no ridge measurement method was conducted.31 Thus, direct comparisons to our work cannot be made. Results from studies, including the present study, found ridge preservation procedures alone cannot entirely maintain the original width of the alveolar ridge. Simon et al.26 suggested an additional GBR overlaid on the buccal and coronal portion of the alveolar bone could help preserved or even slightly augmented the original contour. This suggests a simple intrasocket graft performed in ridge preservation may be inadequate to preserve the baseline contour of the alveolar bone, especially in the maxillary anterior where esthetics are of high concern, so an additional extrasocket overlay graft might be needed. Ridge height loss measured from 4 crestal bone areas around the socket opening was greatest at the midbuccal side. The application of a resorbable collagen membrane to the labial bone partially reduced the vertical alteration. Vertical resorption on other sides including the mesial and distal sides was minimal. An advantage of the ridge preservation procedure is in maintaining the mesial and distal bone height, which is crucial in interdental papilla regeneration at the future implant site especially in areas of high esthetic concern such as the anterior maxilla.32,33 A slight decrease in ridge height from this study was noted compared with pre-
OOOOE Volume 110, Number 5
Kesmas et al. e33
Table III. The comparison of the radiographic density between the grafted socket and the neighboring host bone Immediate postop
1 wk postop
2 mo postop
4 mo postop
Patient
Preop host
Socket
Host
%
Socket
Host
%
Socket
Host
%
Socket
Host
%
1 2 3 4 5 6 7 8
90.89 107.62 104.56 102.17 94.76 77.94 97.93 124.61
95.41 119.01 107.46 102.09 95.81 88.56 90.97 92.39
99.75 93.72 102.88 107.91 105.21 84.59 104.19 131.89
95.65 127.00 104.5 94.61 91.07 104.7 87.31 70.05
89.63 114.79 101.66 — 96.36 77.61 85.41 92.54
119.68 113.92 127.77 — 83.86 80.92 108.52 112.90
74.89 100.80 79.56 — 114.9 95.91 78.70 81.97
81.03 102.48 103.49 88.07 — 86.36 77.08 87.23
132.66 122.34 97.23 101.60 — 86.85 104.36 121.02
61.08 83.77 106.44 86.68 — 99.44 73.86 72.08
71.93 101.83 103.85 94.74 88.66 82.51 80.34 86.66
111.24 101.37 114.95 105.57 97.85 85.92 143.21 129.28
64.66 100.5 90.34 89.74 90.61 96.03 56.10 67.03
Preop, preoperative; postop, postoperative; -, missing data.
Table IV. Radiographic analysis: median percentage of the grafted socket compared with the host bone Treatment
Initial
Reentry
Changes
BCP⫹GBR
95.13
84.98
⫺11.42*
BCP, biphasic calcium phosphate; GBR, guided bone regeneration with a resorbable collagen membrane; —, reduction in radiodensity. *P ⬍ .05 between initial and reentry (4 months postextraction) values.
vious ridge preservation reports.2,24,25,28,30 Iasella et al.27 reported a gain of 1.3 mm ridge height with the use of freeze-dried bone allograft (FDBA) concomitant with collagen membrane for preserving residual ridge contour. However, the vertical dimension on the midpalatal side was preserved. Variations in graft materials and differences in ridge preservation techniques must be considered when judging the present findings against previous studies. Sclar22 claimed ridge preservation performed with a Bio-Col technique could minimize the resorption of alveolar ridge and preserve the soft tissue contours. It could also reduce the need for secondary surgery and attain optimum esthetics with more predictability.34 The Bio-Col technique used bovine bone– derived hydroxyapatite as a graft material filled into the extraction socket. The key difference in this study was the selected bone graft material. BCP (BoneCeramic) is a fully synthetic bone substitute composed of 60% hydroxyapatite and 40% beta-tricalcium phosphate, and thus is not susceptible to any of the drawbacks associated with biological bone substitutes. In our study, histologically, the amount of regenerated bone in the grafted tissue varied with the percentage of newly formed bone between 7% and 83%. Individual variations might be responsible for this wide range, and examination of these reveal some intriguing considerations. Of these 6 specimens, there were 4 specimens
taken from female patients whose ages were in the same range (51-57 years). These 4 female patients were in differing menopausal states, with some receiving hormone therapy. These differences may be reflected in the different rate of healing response after the bonegrafting procedures. The greatest bone formation in Patient 1 may be attributable to her concern in her overall self-care. She had a well-controlled diet including vitamin supplements and regular exercise. Although not completely menopausal, she had been prescribed supplementary calcium for almost 30 years. Two patients (Patients 2 and 7) were also menopausal women without hormone replacement therapy and had a lower bone mass. The important correlation between the amount of calcium intake and bone health status had been well recognized,35,36 although there was no study to point out the effect of calcium supplements on bone graft healing. Erdogan et al.37 had discovered the association between osteoporotic patients and alveolar ridge augmentation. These patients had an increased rate of complications; for instance, resorption of bone graft, nonintegration of bone graft, delayed healing time, and implant failure particularly in the anterior maxilla. This suggests a careful assessment of a patient’s overall bone health/remodeling status should be done with possible alterations in diet suggested before bone regenerative therapies. After the 4-month healing period of this study, the low percentage of residual graft particles detected indicated an appropriate degradation time with good biocompatibility of the material without significant inflammatory response. The amount of residual BCP particles was in the same range as other bone substitutes used for preserving alveolar ridge architecture ranging between 13.5% and 42.0%.27,38,39 The mean BCP remnants of 15.83% ⫾ 8.70% in this study were considerably fewer than found with the use of bovine bone grafts,17,19,22,40 and was significantly lower than the limit set (40%) for acquiring successful implant installation.19
e34
Kesmas et al.
The mean percentage of new bone formation discovered in this study of 28.00% ⫾ 36.75% was in accordance with previous studies of the same material used in sinus augmentation procedures.21,41,42 De Coster et al.31 histologically studied specimens collected from biphasic calcium phosphate–augmented sockets and found the tissue was mainly composed of loosely arranged connective tissue with some mineralized bone. When compared with untreated control sites, the formation of new bone was better than the substituted sites. This result was consistent with the present study. When compared with other ridge preservation studies performed with various bone-grafting materials, the percentage of vital bone from the present study was comparable (range between 26.0% and 68.5%).7,17,19,27-30,43,44 Importantly, an increasing vital bone volume had been disclosed in a BCP augmented sinus from 6 to 8 months. This finding implies that in a BCP augmented site, a longer healing period is beneficial for new bone formation and for additional graft consolidation.41 Other previous studies in animal and human models reported the healing of defects grafted with BCP with persistence of this grafting material at 8 to 9 months following the grafting procedure.31,45,46 These findings were in line with the observations from this study. Incomplete graft consolidation discovered at the 4-month time point suggest an extended healing time of 6 to 8 months before implant placement for superior graft consolidation. Studies using Bio-Oss also observed this xenograft in the grafted site after a 4-month healing period. The implant insertion torque at this grafted site was less than 25 Ncm and the recommended healing time of this type of grafting material was at least 6 to 9 months.47,48 When focusing on the amount of residual graft particles, BCP particles apparently degraded in a shorter period of time, which could have a positive effect on new osseous regeneration. To our knowledge, our study is one of the initial reports of BCP used as bone graft filler in a fresh extraction socket; therefore, there are no studies that strongly validate this assumption. In our study, almost all of the examined biopsies had connective tissue as a predominant component of the specimen. Although the main component was connective tissue, the observation from immunohistochemical staining for OPN indicated the osteogenic potential of the cells embedded within the connective tissue stroma. Osteopontin has been implicated as an important factor in bone remodeling.49 After osteoblastic cell differentiation and maturation, these cells should promote more osseous regeneration over a longer healing time. Thus far, there have been no reports on the expression of bone markers such as OPN in the tissue subsequent to socket augmentation. Our data indicate OPN expres-
OOOOE November 2010
sion can be used in characterizing cells in the augmentation site as having an osteoblastic phenotype. In this study, the radiodensity of the grafted sockets was also evaluated. The BCP grafting material was a radiopaque particle that could be discriminated from the surrounding host bone after application into the extraction socket with a higher density when compared with the host bone. At implant placement, the average density of the grafted socket was lower than that of the host bone. The density of the grafted socket was lower likely because it consisted of several nonmineralized components such as osteoid matrix, fibrous connective tissue, and grafting material. On the other hand, the only component of the neighboring host bone was mature bone with some marrow spaces, which should result in a higher radiodensity. In Patient 2, the healing period was prolonged to 10 months because of poor graft consolidation. The radiodensity of the grafted socket immediately after grafting was much greater than the surrounding host bone. This could suggest that overpacking of the graft might hinder bone graft healing and new bone regeneration by obstructing the revascularization of the vessels.42 In this study, the healing time was limited to 4 months because the purpose of this study was to determine the effectiveness of the selected grafting material over this shorter healing period. However, a longer follow-up period to assess the alteration of radiodensity of the grafted socket is necessary to determine the influence of the material on new bone formation, and studies of radiographic healing of the BCP grafting sites are required to draw any conclusion from the present findings. In our study, the longest follow-up period after prosthetic delivery was almost 12 months. There was no implant-associated complication such as pain, abscess, implant mobility, or loss of implant. No signs of peri-implant mucositis or peri-implantitis were observed. Importantly, the surrounding bone crest was preserved to the level of implant platform without any signs of bone resorption. CONCLUSION The preliminary clinical and histological investigations from this ridge preservation study using BCP in conjunction with a resorbable collagen membrane displayed an encouraging result in preserving alveolar ridge dimension after tooth loss. Moderate vital bone formation could be achieved after a 4-month healing period and tended to increase over time likely by OPN-expressing cells. The amount of unresorbed graft particles were acceptable for implant delivery. Thus, BCP was advantageous in preserving ridge dimension from a clinical perspective. By radio-
OOOOE Volume 110, Number 5
graphic analysis, the appropriate healing time could be judged by observing the decline of the radiodensity of the grafted socket. We show ridge preservation with BCP and a resorbable collagen membrane is useful in maintaining ridge dimension after tooth extraction and reduces the need for future ridge augmentation before dental implant placement. UNCITED REFERENCES This section consists of references that are included in the reference list but are not cited in the article text. Please either cite each of these references in the text or, alternatively, delete it from the reference list. If you do not provide further instruction for this reference, we will retain it in its current form and publish it as an “un-cited reference” with your article.46,47 This section consists of references that are cited in the article text but are not included in the reference list. Please either add each of these references to the reference list or, alternatively, delete it from the text. If you do not provide further instruction for this reference, we will retain it in its current form and publish it as an “un-cited reference” with your article.50 REFERENCES 1. Pietrokovski J, Massler M. Alveolar ridge resorption following tooth extraction. J Prosthet Dent 1967;17:21-7. 2. Lekovic V, Kenney EB, Weinlaender M, Han T, Klokkevold P, Nedic M, et al. A bone regenerative approach to alveolar ridge maintenance following tooth extraction. Report of 10 cases. J Periodontol 1997;68:563-70. 3. Schropp L, Kostopoulos L, Wenzel A. Bone healing following immediate versus delayed placement of titanium implants into extraction sockets: a prospective clinical study. Int J Oral Maxillofac Implants 2003;18:189-99. 4. Werbitt MJ, Goldberg PV. The immediate implant: bone preservation and bone regeneration. Int J Periodontics Restorative Dent 1992;12:206-17. 5. Fowler EB, Breault LG, Rebitski G. Ridge preservation utilizing an acellular dermal allograft and demineralized freeze-dried bone allograft: Part II. Immediate endosseous implant placement. J Periodontol 2000;71:1360-4. 6. Bartee BK. Extraction site reconstruction for alveolar ridge preservation. Part 1: rationale and materials selection. J Oral Implantol 2001;27:187-93. 7. Froum S, Cho SC, Rosenberg E, Rohrer M, Tarnow D. Histological comparison of healing extraction sockets implanted with bioactive glass or demineralized freeze-dried bone allograft: a pilot study. J Periodontol 2002;73:94-102. 8. Block MS. Treatment of the single tooth extraction site. Oral Maxillofac Surg Clin North Am 2004;16:41-63. 9. Reddi AH, Wientroub S, Muthukumaran N. Biologic principles of bone induction. Orthop Clin North Am 1987;18:207-12. 10. Schwartz Z, Mellonig JT, Carnes DL Jr, de la Fontaine J, Cochran DL, Dean DD, et al. Ability of commercial demineralized freeze-dried bone allograft to induce new bone formation. J Periodontol 1996;67:918-26. 11. Zhang M, Powers RMJ, Wolfinbarger LJ. A quantitative assessment of osteoinductivity of human demineralized bone matrix. J Periodontol 1997;68:1076-84.
Kesmas et al. e35 12. Becker W, Urist MR, Tucker LM, Becker BE, Ochsenbein C. Human demineralized freeze-dried bone: inadequate induced bone formation in athymic mice. A preliminary report. J Periodontol 1995;66:822-8. 13. Buser D, Hoffmann B, Bernard JP, Lussi A, Mettler D, Schenk RK. Evaluation of filling materials in membrane-protected bone defects. A comparative histomorphometric study in the mandible of miniature pigs. Clin Oral Implants Res 1998;9:137-50. 14. Hammerle CH, Chiantella GC, Karring T, Lang NP. The effect of a deproteinized bovine bone mineral on bone regeneration around titanium dental implants. Clin Oral Implants Res 1998;9:151-62. 15. Artzi Z, Nemcovsky CE. The application of deproteinized bovine bone mineral for ridge preservation prior to implantation. Clinical and histological observations in a case report. J Periodontol 1998;69:1062-7. 16. Artzi Z, Dayan D, Alpern Y, Nemcovsky CE. Vertical ridge augmentation using xenogenic material supported by a configured titanium mesh: clinicohistopathologic and histochemical study. Int J Oral Maxillofac Implants 2003;18:440-6. 17. Artzi Z, Tal H, Dayan D. Porous bovine bone mineral in healing of human extraction sockets. Part 1: histomorphometric evaluations at 9 months. J Periodontol 2000;71:1015-23. 18. Artzi Z, Tal H, Dayan D. Porous bovine bone mineral in healing of human extraction sockets: 2. Histochemical observations at 9 months. J Periodontol 2001;72:152-9. 19. Carmagnola D, Adriaens P, Berglundh T. Healing of human extraction sockets filled with Bio-Oss. Clin Oral Implants Res 2003;14:137-43. 20. Piattelli A, Scarano A, Mangano C. Clinical and histologic aspects of biphasic calcium phosphate ceramic (BCP) used in connection with implant placement. Biomaterials 1996;17:1767-70. 21. Cordaro L, Bosshardt DD, Palattella P, Rao W, Serino G, Chiapasco M. Maxillary sinus grafting with Bio-Oss or Straumann Bone Ceramic: histomorphometric results from a randomized controlled multicenter clinical trial. Clin Oral Implants Res 2008;19:796-803. 22. Sclar AG. Preserving alveolar ridge anatomy following tooth removal in conjunction with immediate implant placement. The Bio-Col technique. Atlas Oral Maxillofac Surg Clin North Am 1999;7:39-59. 23. Schropp L, Wenzel A, Kostopoulos L, Karring T. Bone healing and soft tissue contour changes following single-tooth extraction: a clinical and radiographic 12-month prospective study. Int J Periodontics Restorative Dent 2003;23:313-23. 24. Lekovic V, Camargo PM, Klokkevold PR, Weinlaender M, Kenney EB, Dimitrijevic B, et al. Preservation of alveolar bone in extraction sockets using bioabsorbable membranes. J Periodontol 1998;69:1044-9. 25. Camargo PM, Lekovic V, Weinlaender M, Klokkevold PR, Kenney EB, Dimitrijevic B, et al. Influence of bioactive glass on changes in alveolar process dimensions after exodontia. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2000;90:581-6. 26. Simon BI, Von Hagen S, Deasy MJ, Faldu M, Resnansky D. Changes in alveolar bone height and width following ridge augmentation using bone graft and membranes. J Periodontol 2000;71:1774-91. 27. Iasella JM, Greenwell H, Miller RL, Hill M, Drisko C, Bohra AA, et al. Ridge preservation with freeze-dried bone allograft and a collagen membrane compared to extraction alone for implant site development: a clinical and histologic study in humans. J Periodontol 2003;74:990-9. 28. Vance GS, Greenwell H, Miller RL, Hill M, Johnston H, Scheetz JP. Comparison of an allograft in an experimental putty carrier and a bovine-derived xenograft used in ridge preservation: a
e36
29.
30.
31.
32.
33.
34. 35. 36. 37.
38.
39.
40.
41.
OOOOE November 2010
Kesmas et al.
clinical and histologic study in humans. Int J Oral Maxillofac Implants 2004;19:491-7. Neiva RF, Tsao YP, Eber R, Shotwell J, Billy E, Wang HL. Effects of a putty-form hydroxyapatite matrix combined with the synthetic cell-binding peptide P-15 on alveolar ridge preservation. J Periodontol 2008;79:291-9. Barone A, Aldini NN, Fini M, Giardino R, Calvo Guirado JL, Covani U. Xenograft versus extraction alone for ridge preservation after tooth removal: a clinical and histomorphometric study. J Periodontol 2008;79:1370-7. De Coster P, Browaeys H, De Bruyn H. Healing of extraction sockets filled with BoneCeramic(R) prior to implant placement: preliminary histological findings. Clin Implant Dent Relat Res 2009 [Epub ahead of print]. Tarnow DP, Magner AW, Fletcher P. The effect of the distance from the contact point to the crest of bone on the presence or absence of the interproximal dental papilla. J Periodontol 1992;63:995-6. Tarnow DP, Cho SC, Wallace SS. The effect of inter-implant distance on the height of inter-implant bone crest. J Periodontol 2000;71:546-9. Sclar A. Soft tissue and esthetic considerations in implant therapy. Chicago: Quintessence; 2003. Heaney RP. Ethnicity, bone status, and the calcium requirement. Nutr Res 2002;22:153-78. Heaney RP. The importance of calcium intake for lifelong skeletal health. Calcif Tissue Int 2002;70:70-3. Erdogan O, Shafer DM, Taxel P, Freilich MA. A review of the association between osteoporosis and alveolar ridge augmentation. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2007;104:738.e1-738.e13. Froum S, Cho SC, Elian N, Rosenberg E, Rohrer M, Tarnow D. Extraction sockets and implantation of hydroxyapatites with membrane barriers: a histologic study. Implant Dent 2004;13: 153-64. Luczyszyn SM, Papalexiou V, Novaes AB Jr, Grisi MF, Souza SL, Taba M Jr. Acellular dermal matrix and hydroxyapatite in prevention of ridge deformities after tooth extraction. Implant Dent 2005;14:176-84. Cardaropoli D, Cardaropoli G. Preservation of the postextraction alveolar ridge: a clinical and histologic study. Int J Periodontics Restorative Dent 2008;28:469-77. Froum SJ, Wallace SS, Cho SC, Elian N, Tarnow DP. Histo-
42.
43.
44.
45.
46.
47.
48.
49.
morphometric comparison of a biphasic bone ceramic to anorganic bovine bone for sinus augmentation: 6- to 8-month postsurgical assessment of vital bone formation. A pilot study. Int J Periodontics Restorative Dent 2008;28:273-81. Friedmann A, Dard M, Kleber BM, Bernimoulin JP, Bosshardt DD. Ridge augmentation and maxillary sinus grafting with a biphasic calcium phosphate: histologic and histomorphometric observations. Clin Oral Implants Res 2009;20:708-14. Serino G, Biancu S, Iezzi G, Piattelli A. Ridge preservation following tooth extraction using a polylactide and polyglycolide sponge as space filler: a clinical and histological study in humans. Clin Oral Implants Res 2003;14:651-8. Wang HL, Tsao YP. Histologic evaluation of socket augmentation with mineralized human allograft. Int J Periodontics Restorative Dent 2008;28:231-7. Jensen SS, Yeo A, Dard M, Hunziker E, Schenk R, Buser D. Evaluation of a novel biphasic calcium phosphate in standardized bone defects: a histologic and histomorphometric study in the mandibles of minipigs. Clin Oral Implants Res 2007;18:752-60. Sculean A, Windisch P, Szendroi-Kiss D, Horvath A, Rosta P, Becker J, et al. Clinical and histologic evaluation of an enamel matrix derivative combined with a biphasic calcium phosphate for the treatment of human intrabony periodontal defects. J Periodontol 2008;79:1991-9. Block MS, Finger I, Lytle R. Human mineralized bone in extraction sites before implant placement: preliminary results. J Am Dent Assoc 2002;133:1631-8. Block MS, Jackson WC. Techniques for grafting the extraction site in preparation for dental implant placement. Atlas Oral Maxillofacial Surg Clin N Am 2006;14:1-25. Sodek J, Ganss B, McKee M. Osteopontin. Crit Rev Oral Biol Med 2000;11:279-303.
Reprint requests: Pornchai Jansisyanont, DDS, MS Department of Oral and Maxillofacial Surgery Faculty of Dentistry Chulalongkorn University 34 Henri-Dunant Rd. Patumwan Bangkok 10330, Thailand [email protected]