- Email: [email protected]
Complications in Alveolar Distraction Osteogenesis: A Clinical Investigation
DENTAL IMPLANTS J Oral Maxillofac Surg 65:267-274, 2007
Complications in Alveolar Distraction Osteogenesis: A Clinical Investigation Nikola Saulacˇic´, DDS, PhD,* Manuel Somosa Martín, DDS, PhD,† Maria de los Angeles Leon Camacho, DDS,‡ and Abel García García, MD, PhD§ Purpose: The purpose of this study was to evaluate distraction osteogenesis for reconstruction of
vertically deficient alveolar ridges and to investigate the occurrence of complications during treatment and the effect of these complications on the final outcome. Patients and Methods: The study included 23 patients who underwent a total of 29 distraction procedures. Two types of distractors were used: intraosseous and juxtaosseous. All of the patients were submitted to the same distraction protocol. The complications occurring during treatment were classified as 1) intraoperative, 2) postoperative, 3) during distraction and consolidation, and 4) postdistraction. Results: The prevalence of cases with complications was 41.37% intraoperative, 24.13% postoperative, 65.51% during distraction and consolidation, and 58.62% postdistraction. Because many complications coincided in some patients, the overall prevalence throughout the treatment was 79.31% of cases; 3.44% of the complications jeopardized subsequent implant placement. Conclusions: Although a high frequency of complications was encountered, severe complications were rare. Most of the complications had simple solutions, and most did not jeopardize the final outcome. Distraction osteogenesis is a viable option for treating vertical alveolar bone defects. © 2007 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 65:267-274, 2007 donor site morbidity.4 Onlay bone grafts undergo resorption and contraction of adjacent soft tissues.5 A decrease in thickness, radiographic density, and overall height (by approximately 25%) of onlay grafts occurs, particularly during the initial 6 months.6 Vertical GBR has proven to be a predictable treatment for achieving vertical bone gain around implants,7 with a very favorable overall implant success rate.2 However, membrane exposure with infection of the implant surface may compromise the final outcome. It also has been suggested that greater bone resorption may occur after membrane removal compared with implants placed in the native bone.8 In contrast to other previously proposed techniques for vertical ridge augmentation, vertical bone gain in alveolar DO is obtained in a more “physiological” way, distant from the previous bone deficiency.9 Distraction of transport segment follows neohistiogenesis, or new soft tissue formation, avoiding difficulties in soft tissue management at the augmentation site. Decreased risk of infection and resorption of distracted alveolar bone are to be expected while the transport segment is attached to the mucoperiosteum and vascularized. Moreover, it has been demonstrated
Various surgical techniques are in use to correct an unfavorable implant–crown relation, including onlay bone grafts,1 vertical guided bone regeneration (GBR),2 and alveolar distraction osteogenesis (DO).3 Bone grafts were previously considered the gold standard, but their use requires second-site surgery, with possible *Assistant Professor, Oral Surgery Unit, School of Dentistry, University of Santiago de Compostela, Santiago de Compostela, Spain. †Assistant Professor, Oral Surgery Unit, School of Dentistry, University of Santiago de Compostela, Santiago de Compostela, Spain. ‡Postgraduate student, Oral Surgery Unit, School of Dentistry, University of Santiago de Compostela, Santiago de Compostela, Spain. §Head of Section, Department of Maxillofacial Surgery, Complejo Hospitalario Universitaro de Santiago, and Professor of Maxillofacial Surgery, University of Santiago de Compostela, Santiago de Compostela, Spain. Address correspondence and reprint requests to Dr García García: Facultad de Odontología, Entrerríos s/n, Santiago de Compostela, Spain; e-mail: [email protected] © 2007 American Association of Oral and Maxillofacial Surgeons
0278-2391/07/6502-0018$32.00/0 doi:10.1016/j.joms.2006.03.049
267
268
COMPLICATIONS IN ALVEOLAR DISTRACTION OSTEOGENESIS
that implants placed in distracted alveolar ridges can successfully withstand the biomechanical demands of implant loading.8 Nevertheless, alveolar DO is a technically sensitive technique, particularly in cases of distraction of basal mandibular bone.10 Several complications, including fracture of the mandible11-13 or transport segment13,14 or breakage of distraction device,13 could compromise the final outcome. Implant placement may be jeopardized due to transport segment displacement, owing to the traction of palatal mucosa or muscles of the floor of the mouth.9,12,15 Besides simultaneous osteogenesis and neohistiogenesis, tissue defect formation at implant placement may necessitate soft tissue augmentation10,14,16,17 or bone grafting,3,13,15,18-20 with possible delay in implant placement.13 Since the first case report on alveolar DO in the literature,21 numerous case series16,18,22-25 and clinical investigations,13,15,26 as well as 2 prospective clinical studies,3,12 have been published. But despite increased interest in recent years, the number of published articles focused on complications during alveolar DO remains limited.10,13,27-31 The aims of the present study were to evaluate the complications occurring during vertical alveolar DO and their effect on treatment outcome, and to suggest possible solutions.
Patients and Methods A total of 23 patients (14 female and 9 male), ranging in age from 23 to 58 years (mean age, 44.59 years), who underwent a total of 29 distraction procedures, were included in the study. The patients presented with varying resorption degrees of alveolar ridges and, among other treatment modalities, chose treatment with a fixed prosthesis. The localization of intervention was 27 mandibular and 2 maxillary (Table 1). Each patient signed a written consent form. Alveolar distraction was performed with 2 types of distractor devices: intraosseous (LEAD System; Leibinger, Freiburg, Germany) and juxtaosseous (MODUS; Medartis, Basel, Switzerland). The type of distractor was chosen considering the location and length of the
Table 1. LOCALIZATION OF SURGICAL INTERVENTION
Location Upper Upper Upper Lower Lower Lower Total
right anterior left left anterior right
N 0 2 0 14 2 11 29
Saulacˇic´ et al. Complications in Alveolar Distraction Osteogenesis. J Oral Maxillofac Surg 2007.
edentulous area. Surgery for distractor placement was performed following the recommendation of Chin,9 as described previously for maxilla32 and mandible.33 Postoperatively, patients received amoxicillin (500 mg/ 8 h for 7 days), ibuprofen (600 mg/8 h for 4 days), and chlorhexidine 0.12% (twice a day for 2 weeks). In all cases, distraction was performed following the same protocol: a latency period of 7 days, a distraction rate of 1 mm/24 h, and a consolidation period of 3 months. Implants were placed after the distractor was removed. The prosthetic restoration of implants was performed after 2 to 4 months of osseointegration. Complications were noted and classified based on the period in which they appeared as 1) intraoperative, 2) postoperative, 3) during distraction and consolidation, or 4) postdistraction.
Results In the 29 distraction procedures performed in the study, 21 were done using the LEAD System and 8 were done using MODUS. In 8 cases, 2 LEAD Systems were inserted in the same transport segment. The span of the distracted alveolar segment ranged from 10 to 42 mm (median, 25.25 ⫾ 8.06 mm). The augmentation performed was between 4 and 10.5 mm (median, 6.37 ⫾ 1.67 mm). Termination of treatment in all cases resulted in augmented alveolar ridges with sufficient stability of the transport segment to permit implant placement. A total of 78 implants, including 58 Straumann (Straumann AG, Basel, Switzerland), 10 Frialoc and 5 Xive (Frialit, Mannheim, Germany), and 5 Replace (Nobel Biocare, Gothenburg, Sweden), were placed in distracted alveolar bone. Between 1 and 4 implants (median, 2.51 ⫾ 0.68) were placed per single distracted segment. All implants were restored with fixed prostheses. The complications occurring with treatment and proposed preventive measures are summarized in Table 2. INTRAOPERATIVE COMPLICATIONS
During surgery, complications occurred in 12 of the cases (41.37%) (Fig 1A). Difficulty completing the osteotomy at the lingual site was encountered in 7 cases. To overcome this problem, we first modified cement spatulas. The ultrasound osteotome used in later cases was found to be more comfortable. Fracture of the transport segment occurred in 3 cases. In 1 case, mobilization of the transport segment fractured a small cortical bone segment that was subsequently removed. In the other 2 cases, the fractured segment was fixed to the transport segment with a miniplate. The threaded rod interfered with occlusion in 3 cases. The excessive length of the rod in 1 case using the LEAD
269
ˇ IC ´ ET AL SAULAC
Table 2. COMPLICATIONS IN ALVEOLAR DISTRACTION OSTEOGENESIS WITH NECESSARY TREATMENT AND SUGGESTED PREVENTIVE MEASURES
Period Intraoperative
Postoperative During distraction and consolidation
Type of Complication Difficulties in completing the osteotomy on the lingual side Fracture of transport segment* Interference of distraction rod with occlusion Paresthesias Hematoma Discomfort
Removal of bone fragment/ osteosynthesis with miniplates Shortening of distractor rod
Incorrect vector of distraction* Ulcers resulted from the components of distractor Bone defect formation
Shortening or early removal of the distraction rod Guided bone regeneration
Perforation of the mucosa
Prevention Measures Use of appropriate instruments
Conservative Conservative Reduction of distraction rate Reduction of distraction rate/secondary suture15 Elimination of the sharp edge Traction9/osteotomy
Suture dehiscence
Postdistraction
Treatment
Mobilization following completed osteotomy Planning with articulator-mounted casts Use of ultrasonic osteotome Minor distraction rate Minor distraction rate Smoothening of alveolar ridge irregularities Orientation of device/distraction rod guidance29 Distraction rod guidance29 Callus massage51
*Compromise the result with possible abolition of the treatment. Saulacˇic´ et al. Complications in Alveolar Distraction Osteogenesis. J Oral Maxillofac Surg 2007.
System was resolved by cutting the inferior part of the rod to the appropriate length before placement. POSTOPERATIVE COMPLICATIONS
Complications due to surgery occurred in 7 cases (24.13%) (Fig 1B). In 1 case, a hematoma appeared that had a spontaneous evolution under antibiotic treatment. Paresthesias occurred in 6 cases (bilaterally in 1 of these cases). These 6 patients were treated with vitamin B, and the paresthesias disappeared within 6 to 8 weeks. COMPLICATIONS DURING DISTRACTION AND CONSOLIDATION
During the active and retention phases, complications occurred in 65.51% of cases (n ⫽ 19); a total of 25 complications were reported (Fig 1C). Four patients reported discomfort (2 pain and 2 tension) during the distraction period. In all cases, the discomfort persisted for 20 minutes after the distraction rod was turned. Pain occurred during distraction of 2 segments in the same patient with augmentations of 7.5 mm and 6 mm. Tension was reported by 1 patient with augmentation of 10.5 mm and another patient with augmentation of 4.5 mm. In all cases, the rate of distraction was decreased to 0.5 mm/24 h, which relieved the discomfort. Dehiscence of the suture line during distraction occurred in 4 patients. Decreasing the distraction rate to 0.5 mm/24 h with topical application of chlorhexi-
dine gel (0.2%) resulted in spontaneous healing within 5 to 7 days. Sharp edges of the transport segment perforated the mucosa in 8 cases. Eliminating the sharp edges with a bur resulted in mucosal overgrowth. As in the cases of discomfort and suture dehiscence, the distraction was not interrupted. Irritation from the tip of the distraction rod produced a decubitus ulcer in 4 cases. In cases where the ulcer occurred in the earlier stages of consolidation, the superior part of the distraction rod was shortened; when the ulcer occurred in the later stages of consolidation, the distraction rod was removed from the alveolar ridge. Due to the traction of the lingual periosteum, an incorrect vector of distraction in the mandible occurred in 4 cases using the LEAD System and in 1 case using MODUS. The median augmentation in these cases was 6.1 ⫾ 1.29 mm. In 1 case, the distraction rod interfered with the opposing teeth during distraction. An incorrect vector of distraction always resulted in an excessive amount of bone on the lingual side. To prevent the inappropriate vector of distraction in 1 case, the threads of the inferior part of the distraction rod were smoothed and inserted deeper into the basal bone. POSTDISTRACTION COMPLICATIONS
In all cases, an adequate amount of keratinized gingiva, without the need for grafting or vestibulo-
270
COMPLICATIONS IN ALVEOLAR DISTRACTION OSTEOGENESIS
transport segment during osteotomy (Fig 2). In 5 cases, an incorrect vector of distraction resulted, with an excessive amount of bone on the lingual side. In 1 of these cases, it was necessary to perform corrective osteotomy and replace the bone segment attached to the periosteum more buccally. Thus, 3.44% of the complications compromised implant placement. Nevertheless, this allowed simultaneous placement of 3 implants in the correct position. After placement, the mesial implant demonstrated bone dehiscence, which was treated with GBR. The placement of 16 implants in 6 distracted ridges in the posterior mandibular region occurred without any previous complications. Therefore, the prevalence of complications during treatment was 79.31%. None of the 78 implants failed during the early stages of osseointegration, and none of the 65 prosthetically restored implants has failed to date, after a follow-up period of 1 to 4 years.
Discussion
FIGURE 1. Prevalence of complications occurring in different periods: A, intraoperative; B, postoperative; C, during distraction and consolidation; D, postdistraction. Saulacˇic´ et al. Complications in Alveolar Distraction Osteogenesis. J Oral Maxillofac Surg 2007.
plasty, was noted at the time of implant placement. Insufficient bone formation in the gap region was the most frequent complication. Of 29 distracted alveolar ridges, bone defect formation was encountered in 17 (58.62%), and a total of 42 implants were placed. All bone defects at the time of implant placement were noted in the buccal side of distracted alveolar ridges, as bone dehiscence (n ⫽ 23; 29.48%) or bone fenestration (n ⫽ 19; 24.35%) of implants (Fig 1D). The treatment of these bone defects was chosen based on the type and size of bone defect. Bone particles obtained from the drill or harvested with a bone scraper were used to cover the implant surface. Any remaining bone defects were filled with bovine bone (Bio-Oss; Geistlich Pharma AG, Wolhusen, Switzerland) in 10 cases and calcium phosphate (FRIOS ALGIPORE; Dentsply Friadent, Mannheim, Germany) in 4 cases. Collagen membrane (Bio-Guide; Geistlich Pharma AG) was used in 9 cases to provide stabilization and protection of the bone fill material. Some cases of bone defect formation coincided with other complications occurring during treatment. In 1 case, dehiscence occurred due to fracture of the
Alveolar DO demonstrates various advantages in treating vertical alveolar bone defects, but its use should be still carefully considered due to the problems related to surgical techniques and devices.34 Moreover, Enislidis et al13 found alveolar distraction to be hazardous and to provide no advantage over conventional methods for vertical augmentation of severely atrophic mandibles. Fracture of the mandible is the most severe complication encountered,11-13,35 indicating need for immediate surgical reposition and ostheosynthesis31; however, this complication
FIGURE 2. Dehiscence defect arising during proximal implant placement in an alveolar ridge that was resolved by guided bone regeneration. The defect occurred due to fracture of the transport segment during osteotomy. Saulacˇic´ et al. Complications in Alveolar Distraction Osteogenesis. J Oral Maxillofac Surg 2007.
ˇ IC ´ ET AL SAULAC
does not indicate treatment failure.11,12 In the present study, we did not note fracture of the mandible, but fracture of the transport segment occurred during surgery in 3 cases. This complication could be also related to severe resorption of the residual bone and smaller transport segment.14 The fractured segments attached to the periosteum were fixed with a miniplate. Along with the possibility of fracture, smaller transport segments are more prone to resorption.9 However, successful cases were described with a minimal mandibular bone height above the canal of 5.5 mm and 6 mm36 and a transport segment thickness of 2 mm.24 Problems associated with terminating the osteotomy at the lingual site were found in the first cases of our study. Bleeding from the floor of the mouth during osteotomy was also described, but without severe consequences.10 To overcome this problem, we used modified cement spatulas. Terminating the osteotomy on the lingual site can also be done by performing a greenstick fracture.37 In our experience, the ultrasonic osteotome has proven much more comfortable, without the risk of damage to the vascular plexa of the floor of the mouth. Interference of the distraction rod with occlusion can be prevented using the mounted casts. Besides using this preoperative measure, interference with the antagonist teeth occurred in 3 cases in our study. Because this situation is readily resolved, it can be considered more a problem than a complication. The prevalence of temporary paresthesias in our study coincided with results of Enislidis13 but was more frequent than that reported by Gaggl et al.26 In all cases, conservative treatment resulted in spontaneous resolution within 6 to 8 weeks, similar to the study of Gaggl et al.26 The use of an ultrasonic osteotome might decrease the risk of nerve damage during osteotomy preparation. One patient developed an extraoral hematoma after surgery. This complication was not specifically related to alveolar DO, however. The patient was treated with antibiotics, which resulted in a spontaneous resolution. Activation of the distraction device is usually pain free25; however, 2 patients in our study reported pain and 2 others reported tension. In all of these cases, the discomfort persisted for no more than 20 minutes, corresponding to the findings of Gaggl et al.26 Pain was reported in augmentations of more than 10 mm with a semirigid distractor10 and in augmentations of more than 14 mm with a rigid distractor.16 However, major augmentations with a rigid distractor were also performed without discomfort.38 The varying amount of distraction performed in patients reporting pain in our study indicated that the occurrence also might be subjective. In both cases in our study, the pain disappeared when the rate of distraction was reduced to
271 0.25 mm/24 h. It is also possible to decrease the single rate and increase the frequency of augmentation without changing the daily rate.16 Parallel or convergent lateral osteotomies during activation may result, with discomfort and friction and possible compromise of the final outcome.12 Orienting lateral osteotomies divergent to one another during surgery is recommended.12,39 Device breakage also has been reported,13,15 which may cause failure of treatment.13 We did not find this complication in our study. In cases of fracture of device components, the distraction must be interrupted and the distractor replaced when possible. All cases of suture dehiscences were resolved by decreasing the distraction rate and using chlorhexidine. Suture dehiscence was also successfully treated with secondary sutures.15,31 Perforation of the mucosa by the sharp edges of the transport segment was encountered more frequently in our study. Removing the sharp edge of bone resulted in spontaneous closure of defect, without infection and influence on the final outcome. Incision dehiscence during initial healing in onlay bone grafting may be considered a treatment failure.40 Graft exposure might result in minor41 or major loss of grafted bone6,42 and implant failure,43 necessitating reoperation and additional bone augmentation.43,44 A high success rate of implant placement can be achieved with vertical GBR, but concerns about soft tissue dehiscence remain with subsequent infection,2,7 necessitating membrane removal.45 Due to the preserved vascularization of the transport segment, bone exposure in alveolar DO might not be considered a complication. Cases of device exposure were also described, but removing exposed parts of device after the activation period did not jeopardize the result.15 In none of the cases with mucosal perforation in the present study was interrupting the augmentation necessary. Conservative measures have been successfully applied to treat infection.13,20,25 A case of initially superficial infection resulting in the loss of a distractor-implant, possibly due to the internal distraction nature of the device, also has been described.25 An incorrect vector of distraction due to the traction of palatal/lingual fibromucosa or the muscles of the floor of the mouth28 is a very frequent complication.3,12-16,46 The rigidity of the system might affect the direction during the process of distraction, but the vector deviation has been described with both types of distractors, semirigid28 and rigid.12 In our study, an incorrect vector of distraction occurred with both types of distractors. It is possible that the amount of augmentation might influence the occurrence of vector deviation. An incorrect vector of distraction was noted in cases with augmentation of
272 more than 5 mm, coinciding with the results of Jensen et al.3 Repositioning of a displaced transport segment is generally performed using an orthodontic appliance,9,12,29 with elastics46 or arch wires,28 with care taken to avoid interference with occlusion. When the distracted bone is already consolidated, it is necessary to perform the osteotomy and fix the transport segment in the correct position.29 In 1 case in the present study, this maneuver permitted simultaneous implant placement. Nevertheless, transport segment displacement could also postpone placement of implants.13 A temporary prosthesis can be used to prevent deviation of the vector.18 Alternatively, the inferior part of the distraction rod in the interforaminal region could be inserted in the basal bone. The vertical gain in alveolar DO is obtained by simultaneous hard and soft tissue formation, but in some cases a vestibuloplasty3,10,14,16,26 or soft tissue graft17 is required. The additional surgical intervention sometimes indicated in onlay bone grafting6 was avoided in our study. Augmentation procedures in our study permitted placement of all implants with sufficient primary stability. However, bone defects were noted in 17 of 29 segments at the time of implant placement. The frequency of bone defect formation and average augmentation performed correspond to the results reported by Jensen et al.3 Follow-up comparisons in experimental models of alveolar DO have demonstrated that bone that was not distracted is significantly thicker than distracted bone and that lingual bone is thicker than labial bone.47 The thickness of distracted alveolar bone might depend on the vascular supply, the amount of augmentation performed, and the mechanical environment during the healing period. Angiogenesis was demonstrated to have a significant influence on osteogenesis during DO.48 In 1968, Kawamura et al49 found that periosteum localized the fracture hematoma and prevented the interposition of soft tissues in DO. Their study showed that limb lengthening of 20% or more resulted in almost complete rupture of the periosteum. Thus, flap elevation and elongation might increase the risk of bone fenestration formation on the buccal cortical bone at implant placement. It is possible that bone defect formation might be related to augmentation of more than 6 mm20 or 25% of initial bone height. The reported prevalence of bone defect formation is between 2.7% and 100%.12,13,15,20 However, the increase in bone defect formation reported in the literature does not always correspond to the increase in average augmentation performed. Moreover, several studies reported no need for bone grafting.8,22,25,46
COMPLICATIONS IN ALVEOLAR DISTRACTION OSTEOGENESIS
Another reason for bone fenestration defects in minor augmentations in our study might be the longer arm of the threaded rod, which increases the instability of the transport segment and impedes new bone formation in the region of the gap.50 Favorable results published on “callus massage”51,52 might indicate this protocol modification to avoid bone defect formation. However, the lack of evidence to date merits further experimental and clinical evaluation of callus massage. Excessive bone formed in the lingual direction due to vector deviation may result in bone dehiscence and the need for additional grafting, with possible delay of implant placement.3,13 Bone dehiscence at implant placement may also be expected due to the possible relapse of the transport segment.19,38,53 A median onlay bone graft height reduction of approximately 25%6 should be considered at the time of bone harvesting. Nevertheless, the relapse in alveolar DO can be readily resolved by including a 20% overcorrection in the active phase of distraction.30 Narrowness of the alveolar ridge before treatment may contribute to bone fenestration or dehiscence from implant placement. Insufficient bone width in the crestal region may be overcome by overcorrection and removal of any sharp crestal edge at the time of implant placement.12 Asymmetric irregularities can be corrected by performing nonuniform distraction using 2 devices, 1 at each end of the transport segment.54 Insufficient alveolar ridge morphology raises the possibility of a staged surgery approach in combined bone grafting and DO procedures.3 Ideally, the decision regarding staged surgery should be made in relation to pre-existing ridge morphology in the early stages of treatment planning.20 Postdistraction narrowing of the alveolar ridge can be best observed on computed tomography (CT) scan (Fig 3), but CT could not be performed in all patients in the present study. In cases of unfavorable predistraction conditions, bone defect formation during implant placement may not be included in the complication rate. Moreover, supplemental grafting should be considered an aspect of distraction therapy and not a result of distraction per se. Initial experimental47 and clinical8 studies demonstrated that implants placed in a distracted alveolar ridge maintain the bone over time just as well as implants placed in the native bone. Despite the high occurrence of bone defect formation in our study, the survival rate of implants during the follow-up period was 100%. Other investigations should evaluate whether implants placed in distracted alveolar bone with and without adequate bone formation can meet the proposed criteria for success.55-57
273
ˇ IC ´ ET AL SAULAC
treatment success rate.8,16,18 Most complications related to surgery can be avoided with adequate treatment planning12 and careful surgical manipulation.14 Consequently, we consider alveolar DO a viable option for treating vertical alveolar bone defects.
References
FIGURE 3. CT scan demonstrating the thickness of bone in the distraction gap compared with nondistracted alveolar bone. Saulacˇic´ et al. Complications in Alveolar Distraction Osteogenesis. J Oral Maxillofac Surg 2007.
In the present study, complications occurred in 79.31% of cases. An even higher prevalence could have been expected, but many complications coincided (eg, a case of vector deviation and bone dehiscence at implant placement). Despite the high rate of complications, alveolar DO always allowed implant placement after treatment. In cases of insufficient bone formation, alveolar DO allowed simultaneous implant placement and bone grafting, avoiding additional surgery and costs. The possibility of distraction to permit an adequate soft tissue drape and cover a large bone graft at the moment of distractor removal should be considered in combined treatment with augmentation of more than 10 mm.20 Regarding the possibility of implant placement, the complication rate in our study was 3.44%. Other frequent complications that did not lead to treatment failure can be considered obstacles or problems.58 Thus, the treatment outcome and implant survival rate in the present study might be considered acceptable. Serious complications, such as infection, fracture of the mandible, or breakage of the distraction device, did not occur in our study. In other published studies, the prevalence of complications that compromised the final outcome is 2.7% to 20%.3,12,13,15,25 Lower survival rates may be related to the complexity of cases and the type of device used. Several studies have reported a 100%
1. Triplett RG, Schow SR: Autologous bone grafts and endosseous implants: Complementary techniques. J Oral Maxillofac Surg 54:486, 1996 2. Simion M, Jovanovic SA, Tinti C, et al: Long-term evaluation of osseointegrated implants inserted at the time or after vertical ridge augmentation: A retrospective study on 123 implants with 1- to 5-year follow-up. Clin Oral Implants Res 12:35, 2001 3. Jensen OT, Cockrell R, Kuhike L, et al: Anterior maxillary alveolar distraction osteogenesis: A prospective 5-year clinical study. Int J Oral Maxillofac Implants 17:52, 2002 4. Clavero J, Lundgren S: Ramus or chin grafts for maxillary sinus inlay and local onlay augmentation: Comparison of donor site morbidity and complications. Clin Implant Dent Relat Res 5:154, 2003 5. Marx RE, Shellenberger T, Wimsatt J, et al: Severely resorbed mandible: Predictable reconstruction with soft tissue matrix expansion (tent pole) grafts. J Oral Maxillofac Surg 60:878, 2002 6. Verhoeven JW, Ruijter J, Cune MS, et al: Onlay grafts in combination with endosseous implants in severe mandibular atrophy: One-year results of a prospective, quantitative radiological study. Clin Oral Implants Res 11:583, 2000 7. Tinti C, Parma-Benfenati S: Vertical ridge augmentation: Surgical protocol and retrospective evaluation of 48 consecutively inserted implants. Int J Periodont Restor Dent 18:434, 1998 8. Chiapasco M, Romeo E, Casentini P, et al: Alveolar distraction osteogenesis versus vertical guided bone regeneration for the correction of vertically deficient edentulous ridges: A 1- to 3-year prospective study on humans. Clin Oral Implants Res 15:82, 2004 9. Chin M: Distraction osteogenesis for dental implants. Atlas Oral Maxillofac Surg Clin North Am 7:41, 1999 10. Uckan S, Dolanmaz D, Kalayci A, et al: Distraction osteogenesis of basal mandibular bone for reconstruction of the alveolar ridge. Br J Oral Maxillofac Surg 40:393, 2002 11. Robiony M, Polini F, Costa F, et al: Osteogenesis distraction and platelet-rich plasma for bone restoration of the severely atrophic mandible: Preliminary results. J Oral Maxillofac Surg 60: 630, 2002 12. Chiapasco M, Consolo U, Bianchi A, et al: Alveolar distraction osteogenesis for the correction of vertically deficient edentulous ridges: A multicenter prospective study on humans. Int J Oral Maxillofac Implants 19:399, 2004 13. Enislidis G, Fock N, Millesi-Schobel G, et al: Analysis of complications following alveolar distraction osteogenesis and implant placement in the partially edentulous mandibles. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 100:25, 2005 14. McAllister BS, Gaffaney TE: Distraction osteogenesis for vertical bone augmentation prior to oral implant reconstruction. Periodontology 2000 33:54, 2003 15. Mazzonetto R, Serra E, Silva FM, et al: Clinical assessment of 40 patients subjected to alveolar distraction osteogenesis. Implant Dent 14:149, 2005 16. Zaffe D, Bertoldi C, Palumbo C, et al: Morphofunctional and clinical study on mandibular alveolar distraction osteogenesis. Clin Oral Implants Res 13:550, 2002 17. Stricker A, Achramm A, Marukawa E, et al: Distraction osteogenesis and tissue engineering—New options for enhancing the implant site. Int J Periodont Restor Dent 23:297, 2003 18. McAllister BS: Histologic and radiographic evidence of vertical ridge augmentation utilizing distraction osteogenesis: 10 consecutively placed distractors. J Periodontol 72:1767, 2001 19. Suhr MA, Kreusch T: Technical considerations in distraction osteogenesis. Int J Oral Maxillofac Surg 33:89, 2004
274 20. Block M, Baughman DG: Reconstruction of severe anterior maxillary defects using distraction osteogenesis, bone grafts, and implants. J Oral Maxillofac Surg 63:291, 2005 21. Chin M, Toth BA: Distraction osteogenesis in maxillofacial surgery using internal devices: Review of five cases. J Oral Maxillofac Surg 54:45, 1996 22. Rachmiel A, Srouji S, Peled M: Alveolar ridge augmentation by distraction osteogenesis. Int J Oral Maxillofac Surg 30:510, 2001 23. Uckan S, Haydar SG, Dolanmaz D: Alveolar distraction: Analysis of 10 cases. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 94:561, 2002 24. Raghoebar GM, Liem RS, Vissink A: Vertical distraction of the severely resorbed edentulous mandible: A clinical, histological and electron microscopic study of 10 treated cases. Clin Oral Implants Res 13:558, 2002 25. Kunkel M, Wahlmann U, Reichert TE, et al: Reconstruction of mandibular defects following tumor ablation by vertical distraction osteogenesis using intraosseous distraction devices. Clin Oral Implants Res 16:89, 2005 26. Gaggl A, Schultes G, Karcher H: Vertical alveolar ridge distraction with prosthetic treatable distractors: A clinical investigation. Int J Oral Maxillofac Implants 15:701, 2000 27. García García A, Somoza Martin M, Gandara Vila P, et al: Minor complications arising in alveolar distraction osteogenesis. J Oral Maxillofac Surg 60:496, 2002 28. Uckan S, Haydar SG, Imirzalioglu P, et al: Repositioning of malpositioned segment during alveolar distraction. J Oral Maxillofac Surg 60:963, 2002 29. Herford AS, Audia F: Maintaining vector control during alveolar distraction osteogenesis: A technical note. Int J Oral Maxillofac Implants 19:758, 2004 30. Saulacic N, Somoza Martin JM, Gándara Vila P, et al: Relapse in alveolar distraction osteogenesis: An indication for overcorrection. J Oral Maxillofac Surg 63:978, 2005 31. Enislidis G, Fock N, Ewers R: Distraction osteogenesis with subperiosteal devices in edentulous mandibles. Br J Oral Maxillofac Surg, in press 32. García García A, Somoza Martin M, Gandara Vila P, et al: Alveolar distraction before insertion of dental implants in the posterior mandible. Br J Oral Maxillofac Surg 41:376, 2003 33. García García A, Somoza Martin JM, Gandara Vila P, et al: Palatal approach for maxillary alveolar distraction. J Oral Maxillofac Surg 62:795, 2004 34. Simion M: Distraction osteogenesis versus onlay bone grafts and guided bone regeneration: What we know and what we suppose. J Oral Maxillofac Surg 60:772, 2002 35. Fukuda M, Iino M, Ohnuki T, et al: Vertical alveolar distraction osteogenesis with complications in a reconstructed mandible. J Oral Implantol 29:185, 2003 36. Hwang SJ, Jung JG, Jung JU, et al: Vertical alveolar bone distraction at molar region using lag screw principle. J Oral Maxillofac Surg 62:787, 2004 37. Nocini PF, Wangerin K, Albanese M, et al: Vertical distraction of a free vascularized fibula flap in a reconstructed hemimandible: Case report. J Craniomaxillofac Surg 28:20, 2000 38. Hidding J, Zoller JE, Lazar F: Micro- and macrodistraction of the jaw: A sure method of adding new bone. Mund Kiefer Gesichtschir 4(Suppl 2):S432, 2000 39. Klug CN, Millesi-Schobel GA, Millesi W, et al: Preprosthetic vertical distraction osteogenesis of the mandible using an L-shaped osteotomy and titanium membranes for guided bone regeneration. J Oral Maxillofac Surg 59:1302, 2001
COMPLICATIONS IN ALVEOLAR DISTRACTION OSTEOGENESIS 40. Schwart-Arad D, Levin L, Sigal L: Surgical success of intraoral autogenous block onlay bone grafting for alveolar ridge augmentation. Implant Dent 14:131, 2005 41. van der Meij EH, Blankestijn J, Berns RM, et al: The combined use of two endosteal implants and iliac crest onlay grafts in the severely atrophic mandible by a modified surgical approach. Int J Oral Maxillofac Surg 34:152, 2005 42. Widmark G, Andersson B, Andrup B, et al: Rehabilitation of patients with severely resorbed maxillae by means of implants with or without bone grafts: A 1-year follow-up study. Int J Oral Maxillofac Implants 13:474, 1998 43. Lekholm U, Wannfors K, Isaksson S, et al: Oral implants in combination with bone grafts: A 3-year retrospective multicenter study using the Brånemark implant system. Int J Oral Maxillofac Surg 28:181, 1999 44. Schwart-Arad D, Levin L: Intraoral autogenous block onlay bone grafting for extensive reconstruction of atrophic maxillary alveolar ridges. J Periodontol 76:636, 2005 45. Fugazzotto PA: Success and failure rates of osseointegrated implants in function in regenerated bone for 6 to 51 months: A preliminary report. Int J Oral Maxillofac Implants 12:17, 1997 46. Urbani G: Alveolar distraction before implantation: A report of five cases and a review of the literature. Int J Periodont Restor Dent 21:569, 2001 47. Block MS, Gardiner D, Almerico B, et al: Loaded hydroxylapatite-coated implants and uncoated titanium-threaded implants in distracted dog alveolar ridges. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 89:676, 2000 48. Fang TD, Salim A, Xia W, et al: Angiogenesis is required for successful bone induction during distraction osteogenesis. J Bone Miner Res 20:1114, 2005 49. Kawamura B, Hosono S, Takahashi T, et al: Limb lengthening by means of subcutaneous osteotomy. J Bone Joint Surg 50: 851, 1968 50. Komuro Y, Takato T, Harii K, et al: The histologic analysis of distraction osteogenesis of the mandible in rabbits. Plast Reconstr Surg 94:152, 1994 51. Mofid MM, Inoue N, Atabey A, et al: Callus stimulation in distraction osteogenesis. Plast Reconstr Surg 15:1621, 2002 52. Lazar FC, Klesper B, Carls P, et al: Callus massage: A new treatment modality for non-unions of the irradiated mandible. Int J Oral Maxillofac Surg 34:202, 2005 53. Huerzeler MB, Zuhr O, Schenk G, et al: Distraction osteogenesis: A treatment tool to improve baseline conditions for esthetic restorations on immediately placed dental implants. A case report. Int J Periodont Restor Dent 22:451, 2002 54. García García A, Somoza Martin M, Gandara Vila P, et al: Alveolar ridge osteogenesis using 2 intraosseous distractors: Uniform and nonuniform distraction. J Oral Maxillofac Surg 60:1510, 2002 55. Adell R, Lekholm U, Rockler B, et al: A 15-year study of osseointegrated implants in the treatment of the edentulous jaw. Int J Oral Surg 10:387, 1981 56. Albrektsson T, Zarb G, Worthington P, et al: The long-term efficacy of currently used dental implants: A review and proposed criteria of success. Int J Oral Maxillofac Implants 1:11, 1986 57. Buser D, Mericske-Stern R, Bernard JP, et al: Long-term evaluation of non-submerged ITI implants. Part 1: 8-year life table analysis of a prospective multicenter study with 2359 implants. Clin Oral Implants Res 8:161, 1997 58. Paley D: Problems, obstacles, and complications of limb lengthening by the Ilizarov technique. Clin Orthop 250:81, 1990
Complications in Alveolar Distraction Osteogenesis: A Clinical Investigation Nikola Saulacˇic´, DDS, PhD,* Manuel Somosa Martín, DDS, PhD,† Maria de los Angeles Leon Camacho, DDS,‡ and Abel García García, MD, PhD§ Purpose: The purpose of this study was to evaluate distraction osteogenesis for reconstruction of
vertically deficient alveolar ridges and to investigate the occurrence of complications during treatment and the effect of these complications on the final outcome. Patients and Methods: The study included 23 patients who underwent a total of 29 distraction procedures. Two types of distractors were used: intraosseous and juxtaosseous. All of the patients were submitted to the same distraction protocol. The complications occurring during treatment were classified as 1) intraoperative, 2) postoperative, 3) during distraction and consolidation, and 4) postdistraction. Results: The prevalence of cases with complications was 41.37% intraoperative, 24.13% postoperative, 65.51% during distraction and consolidation, and 58.62% postdistraction. Because many complications coincided in some patients, the overall prevalence throughout the treatment was 79.31% of cases; 3.44% of the complications jeopardized subsequent implant placement. Conclusions: Although a high frequency of complications was encountered, severe complications were rare. Most of the complications had simple solutions, and most did not jeopardize the final outcome. Distraction osteogenesis is a viable option for treating vertical alveolar bone defects. © 2007 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 65:267-274, 2007 donor site morbidity.4 Onlay bone grafts undergo resorption and contraction of adjacent soft tissues.5 A decrease in thickness, radiographic density, and overall height (by approximately 25%) of onlay grafts occurs, particularly during the initial 6 months.6 Vertical GBR has proven to be a predictable treatment for achieving vertical bone gain around implants,7 with a very favorable overall implant success rate.2 However, membrane exposure with infection of the implant surface may compromise the final outcome. It also has been suggested that greater bone resorption may occur after membrane removal compared with implants placed in the native bone.8 In contrast to other previously proposed techniques for vertical ridge augmentation, vertical bone gain in alveolar DO is obtained in a more “physiological” way, distant from the previous bone deficiency.9 Distraction of transport segment follows neohistiogenesis, or new soft tissue formation, avoiding difficulties in soft tissue management at the augmentation site. Decreased risk of infection and resorption of distracted alveolar bone are to be expected while the transport segment is attached to the mucoperiosteum and vascularized. Moreover, it has been demonstrated
Various surgical techniques are in use to correct an unfavorable implant–crown relation, including onlay bone grafts,1 vertical guided bone regeneration (GBR),2 and alveolar distraction osteogenesis (DO).3 Bone grafts were previously considered the gold standard, but their use requires second-site surgery, with possible *Assistant Professor, Oral Surgery Unit, School of Dentistry, University of Santiago de Compostela, Santiago de Compostela, Spain. †Assistant Professor, Oral Surgery Unit, School of Dentistry, University of Santiago de Compostela, Santiago de Compostela, Spain. ‡Postgraduate student, Oral Surgery Unit, School of Dentistry, University of Santiago de Compostela, Santiago de Compostela, Spain. §Head of Section, Department of Maxillofacial Surgery, Complejo Hospitalario Universitaro de Santiago, and Professor of Maxillofacial Surgery, University of Santiago de Compostela, Santiago de Compostela, Spain. Address correspondence and reprint requests to Dr García García: Facultad de Odontología, Entrerríos s/n, Santiago de Compostela, Spain; e-mail: [email protected] © 2007 American Association of Oral and Maxillofacial Surgeons
0278-2391/07/6502-0018$32.00/0 doi:10.1016/j.joms.2006.03.049
267
268
COMPLICATIONS IN ALVEOLAR DISTRACTION OSTEOGENESIS
that implants placed in distracted alveolar ridges can successfully withstand the biomechanical demands of implant loading.8 Nevertheless, alveolar DO is a technically sensitive technique, particularly in cases of distraction of basal mandibular bone.10 Several complications, including fracture of the mandible11-13 or transport segment13,14 or breakage of distraction device,13 could compromise the final outcome. Implant placement may be jeopardized due to transport segment displacement, owing to the traction of palatal mucosa or muscles of the floor of the mouth.9,12,15 Besides simultaneous osteogenesis and neohistiogenesis, tissue defect formation at implant placement may necessitate soft tissue augmentation10,14,16,17 or bone grafting,3,13,15,18-20 with possible delay in implant placement.13 Since the first case report on alveolar DO in the literature,21 numerous case series16,18,22-25 and clinical investigations,13,15,26 as well as 2 prospective clinical studies,3,12 have been published. But despite increased interest in recent years, the number of published articles focused on complications during alveolar DO remains limited.10,13,27-31 The aims of the present study were to evaluate the complications occurring during vertical alveolar DO and their effect on treatment outcome, and to suggest possible solutions.
Patients and Methods A total of 23 patients (14 female and 9 male), ranging in age from 23 to 58 years (mean age, 44.59 years), who underwent a total of 29 distraction procedures, were included in the study. The patients presented with varying resorption degrees of alveolar ridges and, among other treatment modalities, chose treatment with a fixed prosthesis. The localization of intervention was 27 mandibular and 2 maxillary (Table 1). Each patient signed a written consent form. Alveolar distraction was performed with 2 types of distractor devices: intraosseous (LEAD System; Leibinger, Freiburg, Germany) and juxtaosseous (MODUS; Medartis, Basel, Switzerland). The type of distractor was chosen considering the location and length of the
Table 1. LOCALIZATION OF SURGICAL INTERVENTION
Location Upper Upper Upper Lower Lower Lower Total
right anterior left left anterior right
N 0 2 0 14 2 11 29
Saulacˇic´ et al. Complications in Alveolar Distraction Osteogenesis. J Oral Maxillofac Surg 2007.
edentulous area. Surgery for distractor placement was performed following the recommendation of Chin,9 as described previously for maxilla32 and mandible.33 Postoperatively, patients received amoxicillin (500 mg/ 8 h for 7 days), ibuprofen (600 mg/8 h for 4 days), and chlorhexidine 0.12% (twice a day for 2 weeks). In all cases, distraction was performed following the same protocol: a latency period of 7 days, a distraction rate of 1 mm/24 h, and a consolidation period of 3 months. Implants were placed after the distractor was removed. The prosthetic restoration of implants was performed after 2 to 4 months of osseointegration. Complications were noted and classified based on the period in which they appeared as 1) intraoperative, 2) postoperative, 3) during distraction and consolidation, or 4) postdistraction.
Results In the 29 distraction procedures performed in the study, 21 were done using the LEAD System and 8 were done using MODUS. In 8 cases, 2 LEAD Systems were inserted in the same transport segment. The span of the distracted alveolar segment ranged from 10 to 42 mm (median, 25.25 ⫾ 8.06 mm). The augmentation performed was between 4 and 10.5 mm (median, 6.37 ⫾ 1.67 mm). Termination of treatment in all cases resulted in augmented alveolar ridges with sufficient stability of the transport segment to permit implant placement. A total of 78 implants, including 58 Straumann (Straumann AG, Basel, Switzerland), 10 Frialoc and 5 Xive (Frialit, Mannheim, Germany), and 5 Replace (Nobel Biocare, Gothenburg, Sweden), were placed in distracted alveolar bone. Between 1 and 4 implants (median, 2.51 ⫾ 0.68) were placed per single distracted segment. All implants were restored with fixed prostheses. The complications occurring with treatment and proposed preventive measures are summarized in Table 2. INTRAOPERATIVE COMPLICATIONS
During surgery, complications occurred in 12 of the cases (41.37%) (Fig 1A). Difficulty completing the osteotomy at the lingual site was encountered in 7 cases. To overcome this problem, we first modified cement spatulas. The ultrasound osteotome used in later cases was found to be more comfortable. Fracture of the transport segment occurred in 3 cases. In 1 case, mobilization of the transport segment fractured a small cortical bone segment that was subsequently removed. In the other 2 cases, the fractured segment was fixed to the transport segment with a miniplate. The threaded rod interfered with occlusion in 3 cases. The excessive length of the rod in 1 case using the LEAD
269
ˇ IC ´ ET AL SAULAC
Table 2. COMPLICATIONS IN ALVEOLAR DISTRACTION OSTEOGENESIS WITH NECESSARY TREATMENT AND SUGGESTED PREVENTIVE MEASURES
Period Intraoperative
Postoperative During distraction and consolidation
Type of Complication Difficulties in completing the osteotomy on the lingual side Fracture of transport segment* Interference of distraction rod with occlusion Paresthesias Hematoma Discomfort
Removal of bone fragment/ osteosynthesis with miniplates Shortening of distractor rod
Incorrect vector of distraction* Ulcers resulted from the components of distractor Bone defect formation
Shortening or early removal of the distraction rod Guided bone regeneration
Perforation of the mucosa
Prevention Measures Use of appropriate instruments
Conservative Conservative Reduction of distraction rate Reduction of distraction rate/secondary suture15 Elimination of the sharp edge Traction9/osteotomy
Suture dehiscence
Postdistraction
Treatment
Mobilization following completed osteotomy Planning with articulator-mounted casts Use of ultrasonic osteotome Minor distraction rate Minor distraction rate Smoothening of alveolar ridge irregularities Orientation of device/distraction rod guidance29 Distraction rod guidance29 Callus massage51
*Compromise the result with possible abolition of the treatment. Saulacˇic´ et al. Complications in Alveolar Distraction Osteogenesis. J Oral Maxillofac Surg 2007.
System was resolved by cutting the inferior part of the rod to the appropriate length before placement. POSTOPERATIVE COMPLICATIONS
Complications due to surgery occurred in 7 cases (24.13%) (Fig 1B). In 1 case, a hematoma appeared that had a spontaneous evolution under antibiotic treatment. Paresthesias occurred in 6 cases (bilaterally in 1 of these cases). These 6 patients were treated with vitamin B, and the paresthesias disappeared within 6 to 8 weeks. COMPLICATIONS DURING DISTRACTION AND CONSOLIDATION
During the active and retention phases, complications occurred in 65.51% of cases (n ⫽ 19); a total of 25 complications were reported (Fig 1C). Four patients reported discomfort (2 pain and 2 tension) during the distraction period. In all cases, the discomfort persisted for 20 minutes after the distraction rod was turned. Pain occurred during distraction of 2 segments in the same patient with augmentations of 7.5 mm and 6 mm. Tension was reported by 1 patient with augmentation of 10.5 mm and another patient with augmentation of 4.5 mm. In all cases, the rate of distraction was decreased to 0.5 mm/24 h, which relieved the discomfort. Dehiscence of the suture line during distraction occurred in 4 patients. Decreasing the distraction rate to 0.5 mm/24 h with topical application of chlorhexi-
dine gel (0.2%) resulted in spontaneous healing within 5 to 7 days. Sharp edges of the transport segment perforated the mucosa in 8 cases. Eliminating the sharp edges with a bur resulted in mucosal overgrowth. As in the cases of discomfort and suture dehiscence, the distraction was not interrupted. Irritation from the tip of the distraction rod produced a decubitus ulcer in 4 cases. In cases where the ulcer occurred in the earlier stages of consolidation, the superior part of the distraction rod was shortened; when the ulcer occurred in the later stages of consolidation, the distraction rod was removed from the alveolar ridge. Due to the traction of the lingual periosteum, an incorrect vector of distraction in the mandible occurred in 4 cases using the LEAD System and in 1 case using MODUS. The median augmentation in these cases was 6.1 ⫾ 1.29 mm. In 1 case, the distraction rod interfered with the opposing teeth during distraction. An incorrect vector of distraction always resulted in an excessive amount of bone on the lingual side. To prevent the inappropriate vector of distraction in 1 case, the threads of the inferior part of the distraction rod were smoothed and inserted deeper into the basal bone. POSTDISTRACTION COMPLICATIONS
In all cases, an adequate amount of keratinized gingiva, without the need for grafting or vestibulo-
270
COMPLICATIONS IN ALVEOLAR DISTRACTION OSTEOGENESIS
transport segment during osteotomy (Fig 2). In 5 cases, an incorrect vector of distraction resulted, with an excessive amount of bone on the lingual side. In 1 of these cases, it was necessary to perform corrective osteotomy and replace the bone segment attached to the periosteum more buccally. Thus, 3.44% of the complications compromised implant placement. Nevertheless, this allowed simultaneous placement of 3 implants in the correct position. After placement, the mesial implant demonstrated bone dehiscence, which was treated with GBR. The placement of 16 implants in 6 distracted ridges in the posterior mandibular region occurred without any previous complications. Therefore, the prevalence of complications during treatment was 79.31%. None of the 78 implants failed during the early stages of osseointegration, and none of the 65 prosthetically restored implants has failed to date, after a follow-up period of 1 to 4 years.
Discussion
FIGURE 1. Prevalence of complications occurring in different periods: A, intraoperative; B, postoperative; C, during distraction and consolidation; D, postdistraction. Saulacˇic´ et al. Complications in Alveolar Distraction Osteogenesis. J Oral Maxillofac Surg 2007.
plasty, was noted at the time of implant placement. Insufficient bone formation in the gap region was the most frequent complication. Of 29 distracted alveolar ridges, bone defect formation was encountered in 17 (58.62%), and a total of 42 implants were placed. All bone defects at the time of implant placement were noted in the buccal side of distracted alveolar ridges, as bone dehiscence (n ⫽ 23; 29.48%) or bone fenestration (n ⫽ 19; 24.35%) of implants (Fig 1D). The treatment of these bone defects was chosen based on the type and size of bone defect. Bone particles obtained from the drill or harvested with a bone scraper were used to cover the implant surface. Any remaining bone defects were filled with bovine bone (Bio-Oss; Geistlich Pharma AG, Wolhusen, Switzerland) in 10 cases and calcium phosphate (FRIOS ALGIPORE; Dentsply Friadent, Mannheim, Germany) in 4 cases. Collagen membrane (Bio-Guide; Geistlich Pharma AG) was used in 9 cases to provide stabilization and protection of the bone fill material. Some cases of bone defect formation coincided with other complications occurring during treatment. In 1 case, dehiscence occurred due to fracture of the
Alveolar DO demonstrates various advantages in treating vertical alveolar bone defects, but its use should be still carefully considered due to the problems related to surgical techniques and devices.34 Moreover, Enislidis et al13 found alveolar distraction to be hazardous and to provide no advantage over conventional methods for vertical augmentation of severely atrophic mandibles. Fracture of the mandible is the most severe complication encountered,11-13,35 indicating need for immediate surgical reposition and ostheosynthesis31; however, this complication
FIGURE 2. Dehiscence defect arising during proximal implant placement in an alveolar ridge that was resolved by guided bone regeneration. The defect occurred due to fracture of the transport segment during osteotomy. Saulacˇic´ et al. Complications in Alveolar Distraction Osteogenesis. J Oral Maxillofac Surg 2007.
ˇ IC ´ ET AL SAULAC
does not indicate treatment failure.11,12 In the present study, we did not note fracture of the mandible, but fracture of the transport segment occurred during surgery in 3 cases. This complication could be also related to severe resorption of the residual bone and smaller transport segment.14 The fractured segments attached to the periosteum were fixed with a miniplate. Along with the possibility of fracture, smaller transport segments are more prone to resorption.9 However, successful cases were described with a minimal mandibular bone height above the canal of 5.5 mm and 6 mm36 and a transport segment thickness of 2 mm.24 Problems associated with terminating the osteotomy at the lingual site were found in the first cases of our study. Bleeding from the floor of the mouth during osteotomy was also described, but without severe consequences.10 To overcome this problem, we used modified cement spatulas. Terminating the osteotomy on the lingual site can also be done by performing a greenstick fracture.37 In our experience, the ultrasonic osteotome has proven much more comfortable, without the risk of damage to the vascular plexa of the floor of the mouth. Interference of the distraction rod with occlusion can be prevented using the mounted casts. Besides using this preoperative measure, interference with the antagonist teeth occurred in 3 cases in our study. Because this situation is readily resolved, it can be considered more a problem than a complication. The prevalence of temporary paresthesias in our study coincided with results of Enislidis13 but was more frequent than that reported by Gaggl et al.26 In all cases, conservative treatment resulted in spontaneous resolution within 6 to 8 weeks, similar to the study of Gaggl et al.26 The use of an ultrasonic osteotome might decrease the risk of nerve damage during osteotomy preparation. One patient developed an extraoral hematoma after surgery. This complication was not specifically related to alveolar DO, however. The patient was treated with antibiotics, which resulted in a spontaneous resolution. Activation of the distraction device is usually pain free25; however, 2 patients in our study reported pain and 2 others reported tension. In all of these cases, the discomfort persisted for no more than 20 minutes, corresponding to the findings of Gaggl et al.26 Pain was reported in augmentations of more than 10 mm with a semirigid distractor10 and in augmentations of more than 14 mm with a rigid distractor.16 However, major augmentations with a rigid distractor were also performed without discomfort.38 The varying amount of distraction performed in patients reporting pain in our study indicated that the occurrence also might be subjective. In both cases in our study, the pain disappeared when the rate of distraction was reduced to
271 0.25 mm/24 h. It is also possible to decrease the single rate and increase the frequency of augmentation without changing the daily rate.16 Parallel or convergent lateral osteotomies during activation may result, with discomfort and friction and possible compromise of the final outcome.12 Orienting lateral osteotomies divergent to one another during surgery is recommended.12,39 Device breakage also has been reported,13,15 which may cause failure of treatment.13 We did not find this complication in our study. In cases of fracture of device components, the distraction must be interrupted and the distractor replaced when possible. All cases of suture dehiscences were resolved by decreasing the distraction rate and using chlorhexidine. Suture dehiscence was also successfully treated with secondary sutures.15,31 Perforation of the mucosa by the sharp edges of the transport segment was encountered more frequently in our study. Removing the sharp edge of bone resulted in spontaneous closure of defect, without infection and influence on the final outcome. Incision dehiscence during initial healing in onlay bone grafting may be considered a treatment failure.40 Graft exposure might result in minor41 or major loss of grafted bone6,42 and implant failure,43 necessitating reoperation and additional bone augmentation.43,44 A high success rate of implant placement can be achieved with vertical GBR, but concerns about soft tissue dehiscence remain with subsequent infection,2,7 necessitating membrane removal.45 Due to the preserved vascularization of the transport segment, bone exposure in alveolar DO might not be considered a complication. Cases of device exposure were also described, but removing exposed parts of device after the activation period did not jeopardize the result.15 In none of the cases with mucosal perforation in the present study was interrupting the augmentation necessary. Conservative measures have been successfully applied to treat infection.13,20,25 A case of initially superficial infection resulting in the loss of a distractor-implant, possibly due to the internal distraction nature of the device, also has been described.25 An incorrect vector of distraction due to the traction of palatal/lingual fibromucosa or the muscles of the floor of the mouth28 is a very frequent complication.3,12-16,46 The rigidity of the system might affect the direction during the process of distraction, but the vector deviation has been described with both types of distractors, semirigid28 and rigid.12 In our study, an incorrect vector of distraction occurred with both types of distractors. It is possible that the amount of augmentation might influence the occurrence of vector deviation. An incorrect vector of distraction was noted in cases with augmentation of
272 more than 5 mm, coinciding with the results of Jensen et al.3 Repositioning of a displaced transport segment is generally performed using an orthodontic appliance,9,12,29 with elastics46 or arch wires,28 with care taken to avoid interference with occlusion. When the distracted bone is already consolidated, it is necessary to perform the osteotomy and fix the transport segment in the correct position.29 In 1 case in the present study, this maneuver permitted simultaneous implant placement. Nevertheless, transport segment displacement could also postpone placement of implants.13 A temporary prosthesis can be used to prevent deviation of the vector.18 Alternatively, the inferior part of the distraction rod in the interforaminal region could be inserted in the basal bone. The vertical gain in alveolar DO is obtained by simultaneous hard and soft tissue formation, but in some cases a vestibuloplasty3,10,14,16,26 or soft tissue graft17 is required. The additional surgical intervention sometimes indicated in onlay bone grafting6 was avoided in our study. Augmentation procedures in our study permitted placement of all implants with sufficient primary stability. However, bone defects were noted in 17 of 29 segments at the time of implant placement. The frequency of bone defect formation and average augmentation performed correspond to the results reported by Jensen et al.3 Follow-up comparisons in experimental models of alveolar DO have demonstrated that bone that was not distracted is significantly thicker than distracted bone and that lingual bone is thicker than labial bone.47 The thickness of distracted alveolar bone might depend on the vascular supply, the amount of augmentation performed, and the mechanical environment during the healing period. Angiogenesis was demonstrated to have a significant influence on osteogenesis during DO.48 In 1968, Kawamura et al49 found that periosteum localized the fracture hematoma and prevented the interposition of soft tissues in DO. Their study showed that limb lengthening of 20% or more resulted in almost complete rupture of the periosteum. Thus, flap elevation and elongation might increase the risk of bone fenestration formation on the buccal cortical bone at implant placement. It is possible that bone defect formation might be related to augmentation of more than 6 mm20 or 25% of initial bone height. The reported prevalence of bone defect formation is between 2.7% and 100%.12,13,15,20 However, the increase in bone defect formation reported in the literature does not always correspond to the increase in average augmentation performed. Moreover, several studies reported no need for bone grafting.8,22,25,46
COMPLICATIONS IN ALVEOLAR DISTRACTION OSTEOGENESIS
Another reason for bone fenestration defects in minor augmentations in our study might be the longer arm of the threaded rod, which increases the instability of the transport segment and impedes new bone formation in the region of the gap.50 Favorable results published on “callus massage”51,52 might indicate this protocol modification to avoid bone defect formation. However, the lack of evidence to date merits further experimental and clinical evaluation of callus massage. Excessive bone formed in the lingual direction due to vector deviation may result in bone dehiscence and the need for additional grafting, with possible delay of implant placement.3,13 Bone dehiscence at implant placement may also be expected due to the possible relapse of the transport segment.19,38,53 A median onlay bone graft height reduction of approximately 25%6 should be considered at the time of bone harvesting. Nevertheless, the relapse in alveolar DO can be readily resolved by including a 20% overcorrection in the active phase of distraction.30 Narrowness of the alveolar ridge before treatment may contribute to bone fenestration or dehiscence from implant placement. Insufficient bone width in the crestal region may be overcome by overcorrection and removal of any sharp crestal edge at the time of implant placement.12 Asymmetric irregularities can be corrected by performing nonuniform distraction using 2 devices, 1 at each end of the transport segment.54 Insufficient alveolar ridge morphology raises the possibility of a staged surgery approach in combined bone grafting and DO procedures.3 Ideally, the decision regarding staged surgery should be made in relation to pre-existing ridge morphology in the early stages of treatment planning.20 Postdistraction narrowing of the alveolar ridge can be best observed on computed tomography (CT) scan (Fig 3), but CT could not be performed in all patients in the present study. In cases of unfavorable predistraction conditions, bone defect formation during implant placement may not be included in the complication rate. Moreover, supplemental grafting should be considered an aspect of distraction therapy and not a result of distraction per se. Initial experimental47 and clinical8 studies demonstrated that implants placed in a distracted alveolar ridge maintain the bone over time just as well as implants placed in the native bone. Despite the high occurrence of bone defect formation in our study, the survival rate of implants during the follow-up period was 100%. Other investigations should evaluate whether implants placed in distracted alveolar bone with and without adequate bone formation can meet the proposed criteria for success.55-57
273
ˇ IC ´ ET AL SAULAC
treatment success rate.8,16,18 Most complications related to surgery can be avoided with adequate treatment planning12 and careful surgical manipulation.14 Consequently, we consider alveolar DO a viable option for treating vertical alveolar bone defects.
References
FIGURE 3. CT scan demonstrating the thickness of bone in the distraction gap compared with nondistracted alveolar bone. Saulacˇic´ et al. Complications in Alveolar Distraction Osteogenesis. J Oral Maxillofac Surg 2007.
In the present study, complications occurred in 79.31% of cases. An even higher prevalence could have been expected, but many complications coincided (eg, a case of vector deviation and bone dehiscence at implant placement). Despite the high rate of complications, alveolar DO always allowed implant placement after treatment. In cases of insufficient bone formation, alveolar DO allowed simultaneous implant placement and bone grafting, avoiding additional surgery and costs. The possibility of distraction to permit an adequate soft tissue drape and cover a large bone graft at the moment of distractor removal should be considered in combined treatment with augmentation of more than 10 mm.20 Regarding the possibility of implant placement, the complication rate in our study was 3.44%. Other frequent complications that did not lead to treatment failure can be considered obstacles or problems.58 Thus, the treatment outcome and implant survival rate in the present study might be considered acceptable. Serious complications, such as infection, fracture of the mandible, or breakage of the distraction device, did not occur in our study. In other published studies, the prevalence of complications that compromised the final outcome is 2.7% to 20%.3,12,13,15,25 Lower survival rates may be related to the complexity of cases and the type of device used. Several studies have reported a 100%
1. Triplett RG, Schow SR: Autologous bone grafts and endosseous implants: Complementary techniques. J Oral Maxillofac Surg 54:486, 1996 2. Simion M, Jovanovic SA, Tinti C, et al: Long-term evaluation of osseointegrated implants inserted at the time or after vertical ridge augmentation: A retrospective study on 123 implants with 1- to 5-year follow-up. Clin Oral Implants Res 12:35, 2001 3. Jensen OT, Cockrell R, Kuhike L, et al: Anterior maxillary alveolar distraction osteogenesis: A prospective 5-year clinical study. Int J Oral Maxillofac Implants 17:52, 2002 4. Clavero J, Lundgren S: Ramus or chin grafts for maxillary sinus inlay and local onlay augmentation: Comparison of donor site morbidity and complications. Clin Implant Dent Relat Res 5:154, 2003 5. Marx RE, Shellenberger T, Wimsatt J, et al: Severely resorbed mandible: Predictable reconstruction with soft tissue matrix expansion (tent pole) grafts. J Oral Maxillofac Surg 60:878, 2002 6. Verhoeven JW, Ruijter J, Cune MS, et al: Onlay grafts in combination with endosseous implants in severe mandibular atrophy: One-year results of a prospective, quantitative radiological study. Clin Oral Implants Res 11:583, 2000 7. Tinti C, Parma-Benfenati S: Vertical ridge augmentation: Surgical protocol and retrospective evaluation of 48 consecutively inserted implants. Int J Periodont Restor Dent 18:434, 1998 8. Chiapasco M, Romeo E, Casentini P, et al: Alveolar distraction osteogenesis versus vertical guided bone regeneration for the correction of vertically deficient edentulous ridges: A 1- to 3-year prospective study on humans. Clin Oral Implants Res 15:82, 2004 9. Chin M: Distraction osteogenesis for dental implants. Atlas Oral Maxillofac Surg Clin North Am 7:41, 1999 10. Uckan S, Dolanmaz D, Kalayci A, et al: Distraction osteogenesis of basal mandibular bone for reconstruction of the alveolar ridge. Br J Oral Maxillofac Surg 40:393, 2002 11. Robiony M, Polini F, Costa F, et al: Osteogenesis distraction and platelet-rich plasma for bone restoration of the severely atrophic mandible: Preliminary results. J Oral Maxillofac Surg 60: 630, 2002 12. Chiapasco M, Consolo U, Bianchi A, et al: Alveolar distraction osteogenesis for the correction of vertically deficient edentulous ridges: A multicenter prospective study on humans. Int J Oral Maxillofac Implants 19:399, 2004 13. Enislidis G, Fock N, Millesi-Schobel G, et al: Analysis of complications following alveolar distraction osteogenesis and implant placement in the partially edentulous mandibles. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 100:25, 2005 14. McAllister BS, Gaffaney TE: Distraction osteogenesis for vertical bone augmentation prior to oral implant reconstruction. Periodontology 2000 33:54, 2003 15. Mazzonetto R, Serra E, Silva FM, et al: Clinical assessment of 40 patients subjected to alveolar distraction osteogenesis. Implant Dent 14:149, 2005 16. Zaffe D, Bertoldi C, Palumbo C, et al: Morphofunctional and clinical study on mandibular alveolar distraction osteogenesis. Clin Oral Implants Res 13:550, 2002 17. Stricker A, Achramm A, Marukawa E, et al: Distraction osteogenesis and tissue engineering—New options for enhancing the implant site. Int J Periodont Restor Dent 23:297, 2003 18. McAllister BS: Histologic and radiographic evidence of vertical ridge augmentation utilizing distraction osteogenesis: 10 consecutively placed distractors. J Periodontol 72:1767, 2001 19. Suhr MA, Kreusch T: Technical considerations in distraction osteogenesis. Int J Oral Maxillofac Surg 33:89, 2004
274 20. Block M, Baughman DG: Reconstruction of severe anterior maxillary defects using distraction osteogenesis, bone grafts, and implants. J Oral Maxillofac Surg 63:291, 2005 21. Chin M, Toth BA: Distraction osteogenesis in maxillofacial surgery using internal devices: Review of five cases. J Oral Maxillofac Surg 54:45, 1996 22. Rachmiel A, Srouji S, Peled M: Alveolar ridge augmentation by distraction osteogenesis. Int J Oral Maxillofac Surg 30:510, 2001 23. Uckan S, Haydar SG, Dolanmaz D: Alveolar distraction: Analysis of 10 cases. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 94:561, 2002 24. Raghoebar GM, Liem RS, Vissink A: Vertical distraction of the severely resorbed edentulous mandible: A clinical, histological and electron microscopic study of 10 treated cases. Clin Oral Implants Res 13:558, 2002 25. Kunkel M, Wahlmann U, Reichert TE, et al: Reconstruction of mandibular defects following tumor ablation by vertical distraction osteogenesis using intraosseous distraction devices. Clin Oral Implants Res 16:89, 2005 26. Gaggl A, Schultes G, Karcher H: Vertical alveolar ridge distraction with prosthetic treatable distractors: A clinical investigation. Int J Oral Maxillofac Implants 15:701, 2000 27. García García A, Somoza Martin M, Gandara Vila P, et al: Minor complications arising in alveolar distraction osteogenesis. J Oral Maxillofac Surg 60:496, 2002 28. Uckan S, Haydar SG, Imirzalioglu P, et al: Repositioning of malpositioned segment during alveolar distraction. J Oral Maxillofac Surg 60:963, 2002 29. Herford AS, Audia F: Maintaining vector control during alveolar distraction osteogenesis: A technical note. Int J Oral Maxillofac Implants 19:758, 2004 30. Saulacic N, Somoza Martin JM, Gándara Vila P, et al: Relapse in alveolar distraction osteogenesis: An indication for overcorrection. J Oral Maxillofac Surg 63:978, 2005 31. Enislidis G, Fock N, Ewers R: Distraction osteogenesis with subperiosteal devices in edentulous mandibles. Br J Oral Maxillofac Surg, in press 32. García García A, Somoza Martin M, Gandara Vila P, et al: Alveolar distraction before insertion of dental implants in the posterior mandible. Br J Oral Maxillofac Surg 41:376, 2003 33. García García A, Somoza Martin JM, Gandara Vila P, et al: Palatal approach for maxillary alveolar distraction. J Oral Maxillofac Surg 62:795, 2004 34. Simion M: Distraction osteogenesis versus onlay bone grafts and guided bone regeneration: What we know and what we suppose. J Oral Maxillofac Surg 60:772, 2002 35. Fukuda M, Iino M, Ohnuki T, et al: Vertical alveolar distraction osteogenesis with complications in a reconstructed mandible. J Oral Implantol 29:185, 2003 36. Hwang SJ, Jung JG, Jung JU, et al: Vertical alveolar bone distraction at molar region using lag screw principle. J Oral Maxillofac Surg 62:787, 2004 37. Nocini PF, Wangerin K, Albanese M, et al: Vertical distraction of a free vascularized fibula flap in a reconstructed hemimandible: Case report. J Craniomaxillofac Surg 28:20, 2000 38. Hidding J, Zoller JE, Lazar F: Micro- and macrodistraction of the jaw: A sure method of adding new bone. Mund Kiefer Gesichtschir 4(Suppl 2):S432, 2000 39. Klug CN, Millesi-Schobel GA, Millesi W, et al: Preprosthetic vertical distraction osteogenesis of the mandible using an L-shaped osteotomy and titanium membranes for guided bone regeneration. J Oral Maxillofac Surg 59:1302, 2001
COMPLICATIONS IN ALVEOLAR DISTRACTION OSTEOGENESIS 40. Schwart-Arad D, Levin L, Sigal L: Surgical success of intraoral autogenous block onlay bone grafting for alveolar ridge augmentation. Implant Dent 14:131, 2005 41. van der Meij EH, Blankestijn J, Berns RM, et al: The combined use of two endosteal implants and iliac crest onlay grafts in the severely atrophic mandible by a modified surgical approach. Int J Oral Maxillofac Surg 34:152, 2005 42. Widmark G, Andersson B, Andrup B, et al: Rehabilitation of patients with severely resorbed maxillae by means of implants with or without bone grafts: A 1-year follow-up study. Int J Oral Maxillofac Implants 13:474, 1998 43. Lekholm U, Wannfors K, Isaksson S, et al: Oral implants in combination with bone grafts: A 3-year retrospective multicenter study using the Brånemark implant system. Int J Oral Maxillofac Surg 28:181, 1999 44. Schwart-Arad D, Levin L: Intraoral autogenous block onlay bone grafting for extensive reconstruction of atrophic maxillary alveolar ridges. J Periodontol 76:636, 2005 45. Fugazzotto PA: Success and failure rates of osseointegrated implants in function in regenerated bone for 6 to 51 months: A preliminary report. Int J Oral Maxillofac Implants 12:17, 1997 46. Urbani G: Alveolar distraction before implantation: A report of five cases and a review of the literature. Int J Periodont Restor Dent 21:569, 2001 47. Block MS, Gardiner D, Almerico B, et al: Loaded hydroxylapatite-coated implants and uncoated titanium-threaded implants in distracted dog alveolar ridges. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 89:676, 2000 48. Fang TD, Salim A, Xia W, et al: Angiogenesis is required for successful bone induction during distraction osteogenesis. J Bone Miner Res 20:1114, 2005 49. Kawamura B, Hosono S, Takahashi T, et al: Limb lengthening by means of subcutaneous osteotomy. J Bone Joint Surg 50: 851, 1968 50. Komuro Y, Takato T, Harii K, et al: The histologic analysis of distraction osteogenesis of the mandible in rabbits. Plast Reconstr Surg 94:152, 1994 51. Mofid MM, Inoue N, Atabey A, et al: Callus stimulation in distraction osteogenesis. Plast Reconstr Surg 15:1621, 2002 52. Lazar FC, Klesper B, Carls P, et al: Callus massage: A new treatment modality for non-unions of the irradiated mandible. Int J Oral Maxillofac Surg 34:202, 2005 53. Huerzeler MB, Zuhr O, Schenk G, et al: Distraction osteogenesis: A treatment tool to improve baseline conditions for esthetic restorations on immediately placed dental implants. A case report. Int J Periodont Restor Dent 22:451, 2002 54. García García A, Somoza Martin M, Gandara Vila P, et al: Alveolar ridge osteogenesis using 2 intraosseous distractors: Uniform and nonuniform distraction. J Oral Maxillofac Surg 60:1510, 2002 55. Adell R, Lekholm U, Rockler B, et al: A 15-year study of osseointegrated implants in the treatment of the edentulous jaw. Int J Oral Surg 10:387, 1981 56. Albrektsson T, Zarb G, Worthington P, et al: The long-term efficacy of currently used dental implants: A review and proposed criteria of success. Int J Oral Maxillofac Implants 1:11, 1986 57. Buser D, Mericske-Stern R, Bernard JP, et al: Long-term evaluation of non-submerged ITI implants. Part 1: 8-year life table analysis of a prospective multicenter study with 2359 implants. Clin Oral Implants Res 8:161, 1997 58. Paley D: Problems, obstacles, and complications of limb lengthening by the Ilizarov technique. Clin Orthop 250:81, 1990