- Email: [email protected]
Mandibular bone graft in the anterior maxilla for single-tooth implants
Copyright 9 Munksgaard 1997
lilt. J. Ora[ Maxillo/?tc. Surg. 1997; 26. 106 109
Printed in Denmark. All rights reserved
Mtemadona]Joumal of
Oral8r Maxig@cial Surgery 1SSN 0901-5027
Trauma; oral surgery
Mandibular bone graft in the anterior maxilla for single-tooth
G. Widmark ~, B. Andersson 2, C.-J. IvanoW 1Department of Oral and Maxiliofacial Surgery and 2Clinic of SIM-Prosthetic Dentistry, M61ndal Hospital, M61ndal, Sweden
implants Presentation of a surgical method G. Widmark, B. Andersson, C.-Z Ivanoff" Mandibular bone graft in the anterior maxilla Jor single-tooth implants. Presentation of a surgical method. Int. J. Oral MaxiIlofac. Surg. 1997; 26." 106-109. 9 Munksgaard, 1997 Abstract. Nine patients with 10 implants were included in the study. A bone graft from the symphyseal region of the mandible was used to augment the ridge 4 months before implant insertion. All implant sites showed a sufficient amount of bone at the time of implant insertion. One implant was not integrated at the time of abutment connection. Bone resorption after augmentation was assessed by measurements of the width of the alveolar ridge at four different levels. The measurements were performed before and after the bone-grafting procedure, at implant insertion and at abutment connection. The bone resorption in the buccal/palatal direction was 60% when measured from the time of bone grafting to abutment connection. The bone resorption was already obvious after 4 months (25%). The results indicate that the described bone grafting technique is applicable in patients with a narrow alveolar ridge, even though the resorption of the graft was extensive.
Good initial stability, sufficient bone volume, and adequate bone quality are three important factors influencing the clinical result of implant surgery 2, 7, 17. An aesthetically successful treatment can be achieved if the anatomy of the alveolar ridge permits optimal implant placement. Dentoalveolar trauma, traumatic extraction, infection, and congenitally missing teeth may result in insufficient bone volume, preventing implant placement. In a study of 184 consecutively referred patients for single-tooth implant treatment, ANDERSSON et al. s reported that the most common reason not to insert implants was lack of sufficient bone volume. In less favorable situations, implants can be placed in an optimal position if exposed threads are acceptable4, 12.
One may also use the guided bone regeneration (GBR) technique 13' 14, 20, and KHouRY et al. 18 have described a technique of splitting the alveolar crest and placing a bone graft between the distended bone parts. Extensive resorption of the alveolar ridge may make implant insertion impossible (bone width <4 mm and height <7 mm). The options are either not to insert implants, or to augment the residual ridge with, for instance, a bone graft before, or simultaneously with implant surgery. The advantages and disadvantages of the one- or two-stage procedure have been discussed by TOLMAN24, who reported a survival rate of 85% for immediate implants and 81% for delayed implants in an onlay block procedure.
Key words: maxilla; mandibular bone graft; endosteal implant; resorption. Accepted for publication 13 September 1996
The one-stage procedure has obvious advantages, but requires some residual (4~5 mm) bone. The most common donor site is the anterior iliac cresff although other donor sites such as the posterior iliac crest 6, calvarium 16, and mandibular symphysis have been described 23. The treatment objective in the present study was to create sufficient bone volume with a block bone graft from the chin to allow optimal implant placement. The aim was to determine whether augmentation with bone grafts from the symphyseal region of the mandible, 4 months before implant insertion, was sufficient for total bony coverage of implants and to evaluate clinically the degree of bone resorption.
Mandibular bone g r @
107
Material and methods Eight mcn and one woman with a mean age of 27 years (range 18 46) with a missing upper central incisor with deficient buccal/ palatal dimension (Fig. 1) were included in
6 ~t,u'
Fig. 4. Measurement levels.
Fig. 1. Alveolar crest before grafting.
Fig. 2. Preparation of graft at mandibular donor site.
Fig. 3. Graft placed buccally on alveolar crest.
the study. All patients were healthy and without any significant medical history. Panoramic and intraoral radiographs were taken at the time of examination. No pathology was found in the jaw area to be operated upon. All extractions of the missing tooth had been performed at least 1 year before surgery. The bone augmentation was performed as an outpatient procedure under local anesthesia (2~ lidocaine with epinephrine 12.5 /~g/ml, Xylocain-Adrenalin | Astra, S6dertfilje, Sweden) and sedation. Diazepam (0.3 mg/ kg bodyweight (Stesolid | Dumex, Copenhagen, Denmark) and 2 g phenoxymethylpenicillin (KSvepenin | Astra, S6dertfilje, Sweden) were given orally 1 h preoperatively, and the antibiotic treatment was continued for 10 days, twicc daily. A crestal incision was used and combined with vertical releasing incisions. A mucoperiosteal flap was raised buccally and palatally. The alveolar ridge was clinically examined, and the width was measured with a probe and alveolar ridge calipers. A horizontal incision was made in the vestibule of the anterior mandible. The mental muscles and periosteum were dissected, and the anterior part of the symphysis was exposed. A 2• 1 cm bone graft was prepared, including the buccal cortex. The lingual cortex was left intact (Fig. 2). The preparation was performed with a diamond disk and a 6mm-wide, slightly curved osteotome. The bone was trimmed thereafter, placed on the alveolar crest, and fixed with either one or two microscrews (Fig. 3). No cortical perforations were made on the augmented ridge. The bone graft was used as a buccal onlay in eight patients and as an inlay in a buccopalatal defect in the alveolar crest in one patient (no. 1). The alveolar ridge was exposed both buccally and palatally so that measurements at four different levels (crest top and 3, 6, and 9 m m cranially to the crest level) could be performed without involving the thickness of the mucosa (Fig. 4). A mean value was calculated for all sites before and after augmentation, at implant surgery, and at abutment connection. The crest level was defined as a line between the cementoenamel junction of the adjacent teeth. The bone height (mm) to
the nose cavity, the distance between the adjacent teeth (mm), and bone quality and quantity were recorded by the method of LEKHOLM & ZARB 19. The operation sites were documented with photographs taken before and after bone grafting. The wounds were closed with a nonresorbable 3 0 continuous suture in the symphyseal region and interrupted sutures in the maxilla. Primary clo-
Fig. 5. Augmented area at implant installation (4 months).
Fig. 6. Augmented area at abutment connection (10 months).
108
Widmark e/al.
Tab& 1. hnplant site, type and length; bone quality and quantity according to LEKHOLM& ZARBI9;graft healing time and complications occurring
hnplant site
Bone quality/quantity (LEKI-IOLM ~,4 ZARB 19)
Implant type
5
21 21 21 l1 21 11
B2 B2 B2 C3 C3 B2
15 Self-tap 15 Self-tap 15 Self-tap 13 Self-tap 10 Self-tap 10 4-mm diameter
4 4 3 3.5 3.5 3
6 7 8 9
21 11 11 11
B2 A2 A2 D2
15 Self-tap 18 Mk II 18 Mk II 18 Self-tap
4.5 5 4 4
Patient no. 1 2 3 4
sure was obtained without any tension in the grafted areas. The patients were given instructions about oral hygiene and had 0.2% chlorhexidine rinses twice a day (Corsodyl | Smith Kline Beecham, UK). The patients were not allowed to wear a prosthesis for 2 weeks. Sutures were removed 7 10 days postoperatively, and panoramic and intraoral radiographs were taken at the same visit. Implants were insei~ted 4 months later (range 3 5 months) the same presurgical regimen, including antibiotic coverage, being followed (Fig. 5). The Br~nemark system surgical protocol was followed except for a crestal incisi0n 1. The grafted sites were re-exposed generously both buccally and palatally so that the augmented alveolar crest could be measured at the four levels described previously. Nine self-tapping implants and one 10-mm implant 4 mm in diameter were inserted (for further detail, see Table 1). The postoperative regimen was the same as described above, including radiographic checkup with panoramic and intraoral radiographs. A reassessment of the augmented alveolar ridge was performed at the abutment connection 6 months after implant insertion (Fig. 6). On this occasion, panoramic and intraoral radiographs were taken as well. The bone resorption was calculated as the difference between the bone width measured at the time of grafting, implant insertion, and abutment connection. All patients had allceramic crowns, based on an aluminum oxide cap cemented by the CeraOne system described by ANDERSSONet al 3.
Graft healing time (months)
time of implant surgery, bone integration and remodeling had taken place in all patients. The insertion was performed without problems in seven patients. However, two patients showed minor instability of the bone graft, as a fracture was seen in the border between the graft and the residual alveolar ridge. In one of the same two patients, the implant apex perforated the alveolar crest buccally. This implant was not stable at abutment connection. After removal of the implant, a resorbable membrane was placed over the previous implant site, and 6 months later, an 18-mm selftapping fixture could be installed with primary stability. The niiae remaining implants were found to b e stable at abutment connection. Even though the bone volume was sufficient for full coverage of all implants (n = 10), the resorption of the graft was obvious and varied between the sites. The mean resorption was 25% in the buccal/palatal direction at the time of implant insertion. F r o m the time of bone grafting to abutment connection, the mean resorption was 60%, but the resorption rate showed great variation (Table 2). The soft-tissue healing at the implant and donor sites was uneventful except for a temporary sensory disturbance of the chin region in two patients for 1 month. Radiographically, a small
Complications
Graft fractured at augmentation
Instability of graft at implant installation; implant loss
Instability of graft at implant installation
buccal defect was seen at the donor site at the time of abutment connection. Discussion The method described in the present study made it possible to insert implants when insufficient bone volume was available, and the technique provided enough bone for optimal implant placement without exposed threads. The bone harvested from the mandibular symphysis region consisted mainly of compact bone, giving good primary stability to t h e implants. The results presented are in accordance with those of NYSTROM et al. 21, who found a significant reduction in height and width during the first 3 postoperative months for onlay iliac bone grafts in edentulous maxillae. Voy ARx et al. 2s described a method for reconstruction similar to that described in the present report. However, they used a titanium mesh to secure and cover the graft. Although they did not descr]be an overall resorption rate, a resorption of less than 10% in 15% of the patients was found. One explanation might be that the mesh provided superior stability to the graft and prevented mucosal compression. The chin bone, with its compact structure and probably high level of bone m o r p h o g -
Results The bone quality was of type 2 for eight sites and type 3 for two sites, and the bone quantity differed from A to D according to the index described by LEKHOLM & ZARB 19 (Table 1). At the time of bone augmentation, the surgery was uneventful except for one case where the bone graft fragmented in three parts. These parts were fixed to the recipient site with microscrews. At the
Table 2. Augmentation results measured on four different levels, showing mean value of bone gain and loss
Minimum Maximum Mean Gain/loss
Before grafting
Immediately after grafting
Implant installation (4 months)
Abutment connection (10 months)
0 10 4.8
5 13 9.1 +4.3
2 13 8 - 1.1
0 10 6.5 - 1.5
Mandibular bone graft enic protein ( B M P ) 26, would be expected to have a slow r e s o r p t i o n rate, but the r e s o r p t i o n was extensive in our study. Some a u t h o r s claim that osteogenesis is mainly a t t r i b u t a b l e to the cancellous b o n e 9, 10, 27, which was mainly lacking in the chin graft used. T h e resorption seen would s u p p o r t this view. O n the o t h e r h a n d , some a u t h o r s have r e p o r t e d good resistance to resorption for intram e m b r a n e o u s autografts 25. Pressure by the p e r i o s t e u m on the overcontoured graft m i g h t explain some of the resorption. Lack o f functional stimulus to the area d u r i n g healing could be a n o t h e r reason. L o a d i n g of implants is expected to decrease the resorption rate due to functional remodeling of the b o n e s . A t least some o f the resorption m i g h t be caused by the surgical t r a u m a due to the r a t h e r generous exposure of the graft to enable the measurements. L o n g - t e r m follow-up studies are necessary to show the extent of b o n e resorption in the long run. A l t h o u g h the G B R technique m i g h t be a n alternative m e t h o d for local augm e n t a t i o n of the deficient alveolar ridge13, ~4, the i n t e n t i o n of the present study was to evaluate the b o n e - b l o c k technique described. The b o n y defects in this study were extensive and did n o t p e r m i t optimal i m p l a n t placement, therefore, they were not f o u n d suitable for the G B R technique. T h e use of the G B R t e c h n i q u e is mainly described for localized defects such as fenestrations a n d dehiscences TM 15. I n t r o d u c i n g alloplastic materials such as m e m b r a n e s is k n o w n to cause complications such as m e m b r a n e exposure and infection 4, 11,22. VON ARX et al. 28 lost h a l f o f the graft volume in one p a t i e n t a n d the whole graft in a n o t h e r due to postoperative infection after i n t r o d u c i n g a t i t a n i u m mesh to the grafted area. N o postoperative complications of w o u n d healing a n d infection were seen in the present study. It can be concluded from this study t h a t the described m e t h o d provided e n o u g h b o n e volume for insertion of i m p l a n t s in a n optimal position with total bony coverage. A l t h o u g h b o n e res o r p t i o n was considerable, it did n o t interfere with i m p l a n t insertion.
References 1. ADELL R, LEKHOLM U, BRANEMARKP-I. Surgical procedures. In: BR~.NEMARIr P-I, gARB GA, ALBP,EKTSSON T, eds.: Tissue-
integrated prostheses. Osseointegration in clinical dentistry. Chicago: Quintessence, 1985. 2. ADELL R, LEKHOLM U, GR6NDAHL K, BR~,NEIVIARK P-I, LINDSTR{SM J, JACOBSSON M. Reconstruction of severely resorbed edentulous maxillae using osseointegrated fixtures in immediate autogenous grafts. Int J Oral Maxillofac Impl 1990: 5:233 46. 3. ANDERSSON B, ODMAN P, CARLSSON L, BRXNEMARK P-1. A new BrSnemark single tooth abutment: handling and early clinical experiences. Int J Oral Maxillofac Impl I992: 7:105 11. 4. ANDERSSON B, ODMAN P, WIDMARK G, WAAS A. Anterior tooth replacement with implants in patients with a narrow alveolar ridge form. Clin Oral ImpI Res 1993: 4:90 8. 5. ANDERSSON B, ODMAN P, CARLSSON GE. A study of 184 consecutive patients referred for single-tooth replacement. Clin Oral Impl Res 1995: 6: 232-7. 6. BLOOMQUISTDS, FELDMANGR. The posterior ilium as a donor site for maxillofacial bone grafting. J Max-Fac Surg 1980: 8: 60-4. 7. BRANEMARKP-I, BREINE U, LUNDSTROM J, ADELL R, HANSSON BO, OHLSSON A. Intra-osseous anchorage of dental prosthesis. I. Experimental studies. Scand J Plast Reconstr Surg 1969: 3:81 100. 8. BR~NEMARKP-I. Introduction to osseointegration. In: BR.~NEMARKP-I, gARB GA, ALBP,EKTSSON T, eds.: Tissue-integrated prostheses: osseointegration in clinical dentistry. Chicago: Quintessence, 1985. 9. BURCHARDTH. The biology of bone graft repair. Clin Orthop 1983: 174: 2842. 10. BURWELL RG. The fate of bone grafts. In: APLEY AG, ed.: Recent advances in orthopedics. London: Churchill, 1969. i1. BUSER D, BRAGGERU, LANG NP, NYMAN S. Regeneration and enlargement of jawbone using guided tissue regeneration. Clin Oral Impl Res 1990: 1:22 32. 12. BUSERD, DULA K, HIRT H-R BERTHOLD H. Localized ridge augmentation using guided bone regeneration In: BUSER D, DAHLIN C, SCHENK RK, eds.: Guided bone regeneration in implant dentistry. Chicago: Quintessence, 1994. 13. DAnLIN C, LINDE A, GOTTLOWJ, NYMAN S. Healing of bone defects by guided tissue regeneration. Plast Reconstr Surg 1988: 81: 672-6. 14. DAHLIN C, LEKHOLM U, LINDE A. Membrane-induced bone augmentation at titanium implants. A report on ten fixtures followed from 1 to 3 years after loading. Int J Periodontol Rest Dent 1991: 11: 273-81. 15. DAHL1N C, ANDERSSONL, L1NDEA. Bone augmentation at fenestrated implants by an osteopromotive membrane technique. Clin Oral Impl Res 1991: 2:159 65. 16. HARSHA BC, TURVEY TA, POWERS SK. Use of autogenous cranial bone grafts in maxillo-facial surgery: a preliminary re-
109
port. J Oral Maxillofac Surg 1986: 44: 11 15. 17. JAFnN RA, BERMAN CL. The excessive loss of Brfinemark fixtures in type IV bone: a 5-year analysis. J Periodontol 1991: 62:2 4. 18. KHOURY E Die modifizierte alveolar extensionsplastik. Z Zahnarzt Impl 1987: 3: 174-8. 19. LEKnOLM U, gARB GA. Patient selection and preparation. In: BRANEMARK P-I, gARB GA, ALBREKTSSONT, eds.: Osseointegration in clinical dentistry. Chicago: Quintessence, 1985. 20. MATTOUT P, NOWZARI H, MATTOUT C. Clinical evaluation of guided bone regeneration at exposed parts of Br~_nemark dental implants with and without bone allograft. Clin Oral Impl Res 1995: 6 : 1 8 9 95. 2i. NYSTR6M E, AHLQVISTJ, KAHNBERG KE, ROSENQUIST J. Radiographic evaluation of preoperative bone dimensions, postoperative bone loss, and changes in soft-tissue profile. Int J Oral Maxillofac Surg 1996: 25:351 9. 22. SIMIONM, TRISI P, MAOLIONEM, PIATELU A. A preliminary report on a method for studying the permeability of expanded polytetrafluoroethylene membrane to bacteria in vitro: a scanning electron microscopic and histological study. J Periodontol 1994: 65:755 61. 23. SINDET-PEDERSEN S, ENEMARK H. Mandibular bone grafts for reconstruction of alveolar clefts. J Oral Maxillofac Surg 1988: 46:533 7. 24. TOLMAN DE. Reconstructive procedures with endosseous implants in grafted bone: a review of the literature. Int J Oral Maxillofac Impl 1995: 10: 275-94. 25. gINS JE, WHITAKERLA. Membranous vs endochondral bone: implications for craniofacial reconstruction. Plast Reconstr Surg 1983: 72:778 84. 26. URIST MR. Bone transplant and implants. In: URIST MR, ed.: Fundamental and clinical bone physiology. Philadelphia: JB Lippincott, 1980. 27. URIST MR, DOWELL TA, HAY PH, STRATES BS. Inductive substrates for bone formation. Clin Orthop 1986: 59: 59 96. 28. VON ARX T, HARDT N, WALLKAMM B. The TIME technique: a new method for localized alveolar ridge augmentation prior to placement of dental implants. Int J Oral Maxillofac hnpl 1966: 11:387 94.
Address: Dr Ggran Widmark Department of Oral and Maxill~?/'acial Surgery M6lndal Hospital S-431 80 MO'lndal Sweden
lilt. J. Ora[ Maxillo/?tc. Surg. 1997; 26. 106 109
Printed in Denmark. All rights reserved
Mtemadona]Joumal of
Oral8r Maxig@cial Surgery 1SSN 0901-5027
Trauma; oral surgery
Mandibular bone graft in the anterior maxilla for single-tooth
G. Widmark ~, B. Andersson 2, C.-J. IvanoW 1Department of Oral and Maxiliofacial Surgery and 2Clinic of SIM-Prosthetic Dentistry, M61ndal Hospital, M61ndal, Sweden
implants Presentation of a surgical method G. Widmark, B. Andersson, C.-Z Ivanoff" Mandibular bone graft in the anterior maxilla Jor single-tooth implants. Presentation of a surgical method. Int. J. Oral MaxiIlofac. Surg. 1997; 26." 106-109. 9 Munksgaard, 1997 Abstract. Nine patients with 10 implants were included in the study. A bone graft from the symphyseal region of the mandible was used to augment the ridge 4 months before implant insertion. All implant sites showed a sufficient amount of bone at the time of implant insertion. One implant was not integrated at the time of abutment connection. Bone resorption after augmentation was assessed by measurements of the width of the alveolar ridge at four different levels. The measurements were performed before and after the bone-grafting procedure, at implant insertion and at abutment connection. The bone resorption in the buccal/palatal direction was 60% when measured from the time of bone grafting to abutment connection. The bone resorption was already obvious after 4 months (25%). The results indicate that the described bone grafting technique is applicable in patients with a narrow alveolar ridge, even though the resorption of the graft was extensive.
Good initial stability, sufficient bone volume, and adequate bone quality are three important factors influencing the clinical result of implant surgery 2, 7, 17. An aesthetically successful treatment can be achieved if the anatomy of the alveolar ridge permits optimal implant placement. Dentoalveolar trauma, traumatic extraction, infection, and congenitally missing teeth may result in insufficient bone volume, preventing implant placement. In a study of 184 consecutively referred patients for single-tooth implant treatment, ANDERSSON et al. s reported that the most common reason not to insert implants was lack of sufficient bone volume. In less favorable situations, implants can be placed in an optimal position if exposed threads are acceptable4, 12.
One may also use the guided bone regeneration (GBR) technique 13' 14, 20, and KHouRY et al. 18 have described a technique of splitting the alveolar crest and placing a bone graft between the distended bone parts. Extensive resorption of the alveolar ridge may make implant insertion impossible (bone width <4 mm and height <7 mm). The options are either not to insert implants, or to augment the residual ridge with, for instance, a bone graft before, or simultaneously with implant surgery. The advantages and disadvantages of the one- or two-stage procedure have been discussed by TOLMAN24, who reported a survival rate of 85% for immediate implants and 81% for delayed implants in an onlay block procedure.
Key words: maxilla; mandibular bone graft; endosteal implant; resorption. Accepted for publication 13 September 1996
The one-stage procedure has obvious advantages, but requires some residual (4~5 mm) bone. The most common donor site is the anterior iliac cresff although other donor sites such as the posterior iliac crest 6, calvarium 16, and mandibular symphysis have been described 23. The treatment objective in the present study was to create sufficient bone volume with a block bone graft from the chin to allow optimal implant placement. The aim was to determine whether augmentation with bone grafts from the symphyseal region of the mandible, 4 months before implant insertion, was sufficient for total bony coverage of implants and to evaluate clinically the degree of bone resorption.
Mandibular bone g r @
107
Material and methods Eight mcn and one woman with a mean age of 27 years (range 18 46) with a missing upper central incisor with deficient buccal/ palatal dimension (Fig. 1) were included in
6 ~t,u'
Fig. 4. Measurement levels.
Fig. 1. Alveolar crest before grafting.
Fig. 2. Preparation of graft at mandibular donor site.
Fig. 3. Graft placed buccally on alveolar crest.
the study. All patients were healthy and without any significant medical history. Panoramic and intraoral radiographs were taken at the time of examination. No pathology was found in the jaw area to be operated upon. All extractions of the missing tooth had been performed at least 1 year before surgery. The bone augmentation was performed as an outpatient procedure under local anesthesia (2~ lidocaine with epinephrine 12.5 /~g/ml, Xylocain-Adrenalin | Astra, S6dertfilje, Sweden) and sedation. Diazepam (0.3 mg/ kg bodyweight (Stesolid | Dumex, Copenhagen, Denmark) and 2 g phenoxymethylpenicillin (KSvepenin | Astra, S6dertfilje, Sweden) were given orally 1 h preoperatively, and the antibiotic treatment was continued for 10 days, twicc daily. A crestal incision was used and combined with vertical releasing incisions. A mucoperiosteal flap was raised buccally and palatally. The alveolar ridge was clinically examined, and the width was measured with a probe and alveolar ridge calipers. A horizontal incision was made in the vestibule of the anterior mandible. The mental muscles and periosteum were dissected, and the anterior part of the symphysis was exposed. A 2• 1 cm bone graft was prepared, including the buccal cortex. The lingual cortex was left intact (Fig. 2). The preparation was performed with a diamond disk and a 6mm-wide, slightly curved osteotome. The bone was trimmed thereafter, placed on the alveolar crest, and fixed with either one or two microscrews (Fig. 3). No cortical perforations were made on the augmented ridge. The bone graft was used as a buccal onlay in eight patients and as an inlay in a buccopalatal defect in the alveolar crest in one patient (no. 1). The alveolar ridge was exposed both buccally and palatally so that measurements at four different levels (crest top and 3, 6, and 9 m m cranially to the crest level) could be performed without involving the thickness of the mucosa (Fig. 4). A mean value was calculated for all sites before and after augmentation, at implant surgery, and at abutment connection. The crest level was defined as a line between the cementoenamel junction of the adjacent teeth. The bone height (mm) to
the nose cavity, the distance between the adjacent teeth (mm), and bone quality and quantity were recorded by the method of LEKHOLM & ZARB 19. The operation sites were documented with photographs taken before and after bone grafting. The wounds were closed with a nonresorbable 3 0 continuous suture in the symphyseal region and interrupted sutures in the maxilla. Primary clo-
Fig. 5. Augmented area at implant installation (4 months).
Fig. 6. Augmented area at abutment connection (10 months).
108
Widmark e/al.
Tab& 1. hnplant site, type and length; bone quality and quantity according to LEKHOLM& ZARBI9;graft healing time and complications occurring
hnplant site
Bone quality/quantity (LEKI-IOLM ~,4 ZARB 19)
Implant type
5
21 21 21 l1 21 11
B2 B2 B2 C3 C3 B2
15 Self-tap 15 Self-tap 15 Self-tap 13 Self-tap 10 Self-tap 10 4-mm diameter
4 4 3 3.5 3.5 3
6 7 8 9
21 11 11 11
B2 A2 A2 D2
15 Self-tap 18 Mk II 18 Mk II 18 Self-tap
4.5 5 4 4
Patient no. 1 2 3 4
sure was obtained without any tension in the grafted areas. The patients were given instructions about oral hygiene and had 0.2% chlorhexidine rinses twice a day (Corsodyl | Smith Kline Beecham, UK). The patients were not allowed to wear a prosthesis for 2 weeks. Sutures were removed 7 10 days postoperatively, and panoramic and intraoral radiographs were taken at the same visit. Implants were insei~ted 4 months later (range 3 5 months) the same presurgical regimen, including antibiotic coverage, being followed (Fig. 5). The Br~nemark system surgical protocol was followed except for a crestal incisi0n 1. The grafted sites were re-exposed generously both buccally and palatally so that the augmented alveolar crest could be measured at the four levels described previously. Nine self-tapping implants and one 10-mm implant 4 mm in diameter were inserted (for further detail, see Table 1). The postoperative regimen was the same as described above, including radiographic checkup with panoramic and intraoral radiographs. A reassessment of the augmented alveolar ridge was performed at the abutment connection 6 months after implant insertion (Fig. 6). On this occasion, panoramic and intraoral radiographs were taken as well. The bone resorption was calculated as the difference between the bone width measured at the time of grafting, implant insertion, and abutment connection. All patients had allceramic crowns, based on an aluminum oxide cap cemented by the CeraOne system described by ANDERSSONet al 3.
Graft healing time (months)
time of implant surgery, bone integration and remodeling had taken place in all patients. The insertion was performed without problems in seven patients. However, two patients showed minor instability of the bone graft, as a fracture was seen in the border between the graft and the residual alveolar ridge. In one of the same two patients, the implant apex perforated the alveolar crest buccally. This implant was not stable at abutment connection. After removal of the implant, a resorbable membrane was placed over the previous implant site, and 6 months later, an 18-mm selftapping fixture could be installed with primary stability. The niiae remaining implants were found to b e stable at abutment connection. Even though the bone volume was sufficient for full coverage of all implants (n = 10), the resorption of the graft was obvious and varied between the sites. The mean resorption was 25% in the buccal/palatal direction at the time of implant insertion. F r o m the time of bone grafting to abutment connection, the mean resorption was 60%, but the resorption rate showed great variation (Table 2). The soft-tissue healing at the implant and donor sites was uneventful except for a temporary sensory disturbance of the chin region in two patients for 1 month. Radiographically, a small
Complications
Graft fractured at augmentation
Instability of graft at implant installation; implant loss
Instability of graft at implant installation
buccal defect was seen at the donor site at the time of abutment connection. Discussion The method described in the present study made it possible to insert implants when insufficient bone volume was available, and the technique provided enough bone for optimal implant placement without exposed threads. The bone harvested from the mandibular symphysis region consisted mainly of compact bone, giving good primary stability to t h e implants. The results presented are in accordance with those of NYSTROM et al. 21, who found a significant reduction in height and width during the first 3 postoperative months for onlay iliac bone grafts in edentulous maxillae. Voy ARx et al. 2s described a method for reconstruction similar to that described in the present report. However, they used a titanium mesh to secure and cover the graft. Although they did not descr]be an overall resorption rate, a resorption of less than 10% in 15% of the patients was found. One explanation might be that the mesh provided superior stability to the graft and prevented mucosal compression. The chin bone, with its compact structure and probably high level of bone m o r p h o g -
Results The bone quality was of type 2 for eight sites and type 3 for two sites, and the bone quantity differed from A to D according to the index described by LEKHOLM & ZARB 19 (Table 1). At the time of bone augmentation, the surgery was uneventful except for one case where the bone graft fragmented in three parts. These parts were fixed to the recipient site with microscrews. At the
Table 2. Augmentation results measured on four different levels, showing mean value of bone gain and loss
Minimum Maximum Mean Gain/loss
Before grafting
Immediately after grafting
Implant installation (4 months)
Abutment connection (10 months)
0 10 4.8
5 13 9.1 +4.3
2 13 8 - 1.1
0 10 6.5 - 1.5
Mandibular bone graft enic protein ( B M P ) 26, would be expected to have a slow r e s o r p t i o n rate, but the r e s o r p t i o n was extensive in our study. Some a u t h o r s claim that osteogenesis is mainly a t t r i b u t a b l e to the cancellous b o n e 9, 10, 27, which was mainly lacking in the chin graft used. T h e resorption seen would s u p p o r t this view. O n the o t h e r h a n d , some a u t h o r s have r e p o r t e d good resistance to resorption for intram e m b r a n e o u s autografts 25. Pressure by the p e r i o s t e u m on the overcontoured graft m i g h t explain some of the resorption. Lack o f functional stimulus to the area d u r i n g healing could be a n o t h e r reason. L o a d i n g of implants is expected to decrease the resorption rate due to functional remodeling of the b o n e s . A t least some o f the resorption m i g h t be caused by the surgical t r a u m a due to the r a t h e r generous exposure of the graft to enable the measurements. L o n g - t e r m follow-up studies are necessary to show the extent of b o n e resorption in the long run. A l t h o u g h the G B R technique m i g h t be a n alternative m e t h o d for local augm e n t a t i o n of the deficient alveolar ridge13, ~4, the i n t e n t i o n of the present study was to evaluate the b o n e - b l o c k technique described. The b o n y defects in this study were extensive and did n o t p e r m i t optimal i m p l a n t placement, therefore, they were not f o u n d suitable for the G B R technique. T h e use of the G B R t e c h n i q u e is mainly described for localized defects such as fenestrations a n d dehiscences TM 15. I n t r o d u c i n g alloplastic materials such as m e m b r a n e s is k n o w n to cause complications such as m e m b r a n e exposure and infection 4, 11,22. VON ARX et al. 28 lost h a l f o f the graft volume in one p a t i e n t a n d the whole graft in a n o t h e r due to postoperative infection after i n t r o d u c i n g a t i t a n i u m mesh to the grafted area. N o postoperative complications of w o u n d healing a n d infection were seen in the present study. It can be concluded from this study t h a t the described m e t h o d provided e n o u g h b o n e volume for insertion of i m p l a n t s in a n optimal position with total bony coverage. A l t h o u g h b o n e res o r p t i o n was considerable, it did n o t interfere with i m p l a n t insertion.
References 1. ADELL R, LEKHOLM U, BRANEMARKP-I. Surgical procedures. In: BR~.NEMARIr P-I, gARB GA, ALBP,EKTSSON T, eds.: Tissue-
integrated prostheses. Osseointegration in clinical dentistry. Chicago: Quintessence, 1985. 2. ADELL R, LEKHOLM U, GR6NDAHL K, BR~,NEIVIARK P-I, LINDSTR{SM J, JACOBSSON M. Reconstruction of severely resorbed edentulous maxillae using osseointegrated fixtures in immediate autogenous grafts. Int J Oral Maxillofac Impl 1990: 5:233 46. 3. ANDERSSON B, ODMAN P, CARLSSON L, BRXNEMARK P-1. A new BrSnemark single tooth abutment: handling and early clinical experiences. Int J Oral Maxillofac Impl I992: 7:105 11. 4. ANDERSSON B, ODMAN P, WIDMARK G, WAAS A. Anterior tooth replacement with implants in patients with a narrow alveolar ridge form. Clin Oral ImpI Res 1993: 4:90 8. 5. ANDERSSON B, ODMAN P, CARLSSON GE. A study of 184 consecutive patients referred for single-tooth replacement. Clin Oral Impl Res 1995: 6: 232-7. 6. BLOOMQUISTDS, FELDMANGR. The posterior ilium as a donor site for maxillofacial bone grafting. J Max-Fac Surg 1980: 8: 60-4. 7. BRANEMARKP-I, BREINE U, LUNDSTROM J, ADELL R, HANSSON BO, OHLSSON A. Intra-osseous anchorage of dental prosthesis. I. Experimental studies. Scand J Plast Reconstr Surg 1969: 3:81 100. 8. BR~NEMARKP-I. Introduction to osseointegration. In: BR.~NEMARKP-I, gARB GA, ALBP,EKTSSON T, eds.: Tissue-integrated prostheses: osseointegration in clinical dentistry. Chicago: Quintessence, 1985. 9. BURCHARDTH. The biology of bone graft repair. Clin Orthop 1983: 174: 2842. 10. BURWELL RG. The fate of bone grafts. In: APLEY AG, ed.: Recent advances in orthopedics. London: Churchill, 1969. i1. BUSER D, BRAGGERU, LANG NP, NYMAN S. Regeneration and enlargement of jawbone using guided tissue regeneration. Clin Oral Impl Res 1990: 1:22 32. 12. BUSERD, DULA K, HIRT H-R BERTHOLD H. Localized ridge augmentation using guided bone regeneration In: BUSER D, DAHLIN C, SCHENK RK, eds.: Guided bone regeneration in implant dentistry. Chicago: Quintessence, 1994. 13. DAnLIN C, LINDE A, GOTTLOWJ, NYMAN S. Healing of bone defects by guided tissue regeneration. Plast Reconstr Surg 1988: 81: 672-6. 14. DAHLIN C, LEKHOLM U, LINDE A. Membrane-induced bone augmentation at titanium implants. A report on ten fixtures followed from 1 to 3 years after loading. Int J Periodontol Rest Dent 1991: 11: 273-81. 15. DAHL1N C, ANDERSSONL, L1NDEA. Bone augmentation at fenestrated implants by an osteopromotive membrane technique. Clin Oral Impl Res 1991: 2:159 65. 16. HARSHA BC, TURVEY TA, POWERS SK. Use of autogenous cranial bone grafts in maxillo-facial surgery: a preliminary re-
109
port. J Oral Maxillofac Surg 1986: 44: 11 15. 17. JAFnN RA, BERMAN CL. The excessive loss of Brfinemark fixtures in type IV bone: a 5-year analysis. J Periodontol 1991: 62:2 4. 18. KHOURY E Die modifizierte alveolar extensionsplastik. Z Zahnarzt Impl 1987: 3: 174-8. 19. LEKnOLM U, gARB GA. Patient selection and preparation. In: BRANEMARK P-I, gARB GA, ALBREKTSSONT, eds.: Osseointegration in clinical dentistry. Chicago: Quintessence, 1985. 20. MATTOUT P, NOWZARI H, MATTOUT C. Clinical evaluation of guided bone regeneration at exposed parts of Br~_nemark dental implants with and without bone allograft. Clin Oral Impl Res 1995: 6 : 1 8 9 95. 2i. NYSTR6M E, AHLQVISTJ, KAHNBERG KE, ROSENQUIST J. Radiographic evaluation of preoperative bone dimensions, postoperative bone loss, and changes in soft-tissue profile. Int J Oral Maxillofac Surg 1996: 25:351 9. 22. SIMIONM, TRISI P, MAOLIONEM, PIATELU A. A preliminary report on a method for studying the permeability of expanded polytetrafluoroethylene membrane to bacteria in vitro: a scanning electron microscopic and histological study. J Periodontol 1994: 65:755 61. 23. SINDET-PEDERSEN S, ENEMARK H. Mandibular bone grafts for reconstruction of alveolar clefts. J Oral Maxillofac Surg 1988: 46:533 7. 24. TOLMAN DE. Reconstructive procedures with endosseous implants in grafted bone: a review of the literature. Int J Oral Maxillofac Impl 1995: 10: 275-94. 25. gINS JE, WHITAKERLA. Membranous vs endochondral bone: implications for craniofacial reconstruction. Plast Reconstr Surg 1983: 72:778 84. 26. URIST MR. Bone transplant and implants. In: URIST MR, ed.: Fundamental and clinical bone physiology. Philadelphia: JB Lippincott, 1980. 27. URIST MR, DOWELL TA, HAY PH, STRATES BS. Inductive substrates for bone formation. Clin Orthop 1986: 59: 59 96. 28. VON ARX T, HARDT N, WALLKAMM B. The TIME technique: a new method for localized alveolar ridge augmentation prior to placement of dental implants. Int J Oral Maxillofac hnpl 1966: 11:387 94.
Address: Dr Ggran Widmark Department of Oral and Maxill~?/'acial Surgery M6lndal Hospital S-431 80 MO'lndal Sweden