Alveolar distraction osteogenesis for oral rehabilitation in reconstructed jaws.

PURPOSE OF REVIEW: To present a literature review of alveolar distraction osteogenesis (ADO) for reconstructed jaws, with emphasis on indications, critical surgical factors, protocols and complications for oral rehabilitation of reconstructed jaws. RECENT FINDINGS: The defects in jaw result mostly from malignancy, benign tumor or gunshot injury. Jaw reconstructions were performed mostly by vascularized fibula graft. Alveolar distraction was primarily indicated to correct vertical discrepancy between the reconstructed region and residual ridge in order to achieve adequate height of the transplanted bone prior to implant placement. The vertical bone height gained ranged from 6 to 15 mm. The most common complications reported were infections and distractor malalignment. SUMMARY: This review reveals few numbers of case series on this topic. However, ADO in reconstructed jaws can produce consistent evidence of bone regeneration, with stable augmentation results clinically, histologically and radiographically, thus making it a predictable surgical procedure prior to oral implant rehabilitation.

Computer-aided maxillofacial surgery: an update.

INTRODUCTION: Recent developments in technology have revolutionized medicine and surgery. This article aims at providing an update on the current trends in computer-aided maxillofacial surgery and illustrates these advances with clinical cases. METHODS: The PubMed database was searched for articles published during the past 5 years using the keywords "maxillofacial" and "surgery, computer-assisted." Full texts of relevant articles were retrieved, and their study details were extracted. RESULTS: Among the 133 articles, most focused on cone-beam computed tomography (CBCT), stereophotography, surgical panning software, and intraoperative navigation. Stereophotography produces 3D facial photographs with natural color and texture, whereas CBCT generates excellent hard-tissue images with a substantially lower radiation than conventional CT scans. Information gathered from CBCT and stereophotography can be used for accurate diagnosis, virtual planning, and simulation of surgery with the aid of specialized software. The preplanned treatment can be executed accurately via intraoperative surgical navigation. CONCLUSION: Tremendous potential exists for computer-aided maxillofacial surgery as it moves from research to clinical care.

Endoscope-assisted rigid fixation for intraoral vertical subsigmoid osteotomy: a preliminary clinical study.

PURPOSE: To illustrate the clinical technique of endoscope-assisted rigid fixation in intraoral vertical subsigmoid osteotomy and to report on early postoperative morbidities. MATERIALS AND METHODS: Six patients presenting with Class III skeletal profile were recruited. The osteotomy was performed through an intraoral route. Rigid fixation was achieved with a 3-mm stab incision located inferior to the ear pinna, allowing access to the transbuccal trocar. A rigid endoscope was introduced intraorally to improve visibility during fixation. Each patient's preoperative and 3-month postoperative radiographs and clinical morbidities (neurosensory status and temporomandibular joint function) were assessed. RESULTS: Most patients (83.3%) fully recovered inferior alveolar nerve function, and 66.6% recovered temporomandibular joint function. The scar from the stab incision was effectively camouflaged by the ear pinna and was not noticeable to the patients. CONCLUSION: This preliminary study confirms that the application of endoscope-assisted rigid fixation in intraoral vertical subsigmoid osteotomy is clinically feasible. All patients presented with minimal clinical morbidities and good stability at the early postoperative period.

Three-dimensional photogrammetry for surgical planning of tissue expansion in hemifacial microsomia.

BACKGROUND: We aim to illustrate the applications of 3-dimensional (3-D) photogrammetry for surgical planning and longitudinal assessment of the volumetric changes in hemifacial microsomia. METHODS: A 3-D photogrammetric system was employed for planning soft tissue expansion and transplantation of a vascularized scapular flap for a patient with hemifacial microsomia. The facial deficiency was calculated by superimposing a mirror of the normal side on the preoperative image. Postsurgical volumetric changes were monitored by serial superimposition of 3-D images. RESULTS: A total of 31 cm(3) of tissue expansion was achieved within a period of 4 weeks. A scapular free flap measuring 8 cm × 5 cm was transplanted to augment the facial deficiency. Postsurgical shrinkage of the flap was observed mainly in the first 3 months and it was minimal thereafter. CONCLUSION: 3-D photogrammetry can be used as a noninvasive objective tool for assessing facial deformity, planning, and postoperative follow-up of surgical correction of facial asymmetry.

Safety of coronectomy versus excision of wisdom teeth: a randomized controlled trial.

OBJECTIVE: The objective of this study was to compare the surgical complications and neurosensory disturbances of coronectomy and total excision of lower wisdom teeth with roots in close proximity to the inferior dental nerve (IDN). STUDY DESIGN: A randomized controlled trial was conducted to compare the surgical complications and IDN deficit of coronectomy and total removal of wisdom teeth. Patients with specific radiographic signs of close proximity of wisdom teeth roots to the IDN were randomized. RESULTS: A total of 231 patients underwent surgery for 349 lower wisdom teeth (171 coronectomies, 178 controls); 16 coronectomies failed and were removed in total. Nine patients in the control group presented with IDN deficit, compared with 1 in coronectomy group (P = .023). Pain and dry socket incidence was significantly lower in the coronectomy group, and there were no statistical differences in infection rate between the 2 groups. Reoperation of one coronectomy case was performed owing to persistent root exposure. CONCLUSION: There are fewer complications in terms of IDN deficit, pain, and dry socket after coronectomy, but the infection rate is similar to that of total excision.

Comparison of two resorbable membrane systems in bone regeneration after removal of wisdom teeth: a randomized-controlled clinical pilot study.

OBJECTIVES: To compare the performance and safety of Inion GTR(TM) Biodegradable Membrane System and Geistlich resorbable bilayer Bio-Gide((R)) membrane in human bone regeneration. MATERIAL AND METHODS: In a multicenter, split blind, comparative, randomized, prospective, pilot study 15 patients have been randomized at surgery whether to be treated either with Inion GTR(TM) Biodegradable Membrane System on one and Geistlich resorbable bilayer Bio-Gide((R)) membrane on the other side or vice versa after surgical removal of both fully impacted wisdom teeth. During the follow-up visits at week 1, 2 and 6 and at months 3 and 6 the general state, the wound, eventual adverse events and the medication of the patients were assessed. Computed Tomography (CT) scans were performed immediately and 3 months after the surgery, before biopsy collection. Semi-quantitative histological evaluation and histomorphometric analyses were performed according to the ISO 10993-6 standard. New bone formation and membrane integration were evaluated by CT scan measurements. Tissue healing was evaluated clinically and by photographs between the time on teeth extraction and during follow ups. RESULTS: Five patients were smokers, none drank alcohol. Mild adverse events like wound infection, haematoma or late swelling of the gums occurred in three patients. The trephine bur harvest of bone biopsies under local anaesthesia was uneventful. Whereas specimens from the sites treated with the Inion membrane yielded 17.0% (SD 24%), the Bio-Gide membrane sites yielded 13.5% (SD 15%) of bone tissue density. In sites treated with the Inion membrane, 9.5% of old bone density and 7.5% of newly formed bone could be found, whereas the Bio-Gide((R)) membrane sites showed 3.8% of old bone density and 9.8% of newly formed bone. There were no statistically significant differences between the two groups with respect to the two variables. The osteoid rim was more extended with the Bio-Gide((R)) (6.6 mm) than with the Inion membrane (5.1 mm) but the difference between the two treatments did not reach statistical significance. Highly significant reductions in the area of the defect with both membranes were detected with significant increases in CT density at the immediate inferio-buccal adjacent bone and in the surgical defect area with both membranes. However, there was neither significant change in CT density in the immediate inferior-lingual adjacent bone of the two membranes, nor significant difference between the membranes on any of the four measurements (area of defect: P=0.1354; CT density immediate inferio-buccal adjacent bone: P=0.7615; CT density surgical defect area: P=0.1876; CT density immediate inferio-lingual adjacent bone: P=0.4212). CONCLUSION: The overall clinical outcome was satisfying and the majority of the patients showed an uneventful healing phase. Both membranes presented similar capacities regarding their barrier function and were associated with analogous bone regeneration. No statistically valid evidence about the superiority of one particular membrane was obtained. For the patient the only difference is that one product is animal derived and the other synthetic.

Transport distraction versus costochondral graft for reconstruction of temporomandibular joint ankylosis: which is better?

OBJECTIVE: This study compared the methods of transport distraction and costochondral graft in reconstruction of temporomandibular joint (TMJ) ankylosis. STUDY DESIGN: Bilateral bony TMJ ankylosis was induced in 12 adult goats. Transport distraction of the mandibular ramus was performed on one side, whereas costochondral graft was performed on the other side. Jaw movements, TMJ healing, condylar remodeling, and recurrence of ankylosis were assessed by clinical, radiological, and histological examinations. RESULTS: Both transport distraction and costochondral graft established a neo-condyle separating from the pseudo-disc with a joint space. The ankylosis scores were higher in the distraction side in the first 12 weeks. Both techniques showed no significant difference in the calcification scores and recurrence of ankylosis in the long term. The maximal jaw movements in 3 directions returned to the pre-ankylosis stage by both methods. CONCLUSIONS: Distraction osteogenesis is an effective reconstruction method for TMJ ankylosis, matching the gold standard of costochondral grafting.

Meta-analysis of mandibular distraction osteogenesis: clinical applications and functional outcomes.

BACKGROUND: Mandibular distraction osteogenesis has been used effectively to treat syndromic craniofacial deformities. In recent years, its scope of application has widened to include treatment of airway obstruction in adults and children and nonsyndromic class II mandibular hypoplasia. So far, there has been no evidence-based review of mandibular distraction osteogenesis for mandibular lengthening. METHODS: Two rounds of searches were performed by two independent assessors. The first-round PubMed search used the keywords "mandible" and "distraction osteogenesis." In the second-round search, the reference lists of the articles were retrieved. For both rounds, abstracts and then full articles were reviewed and selected on the basis of a set of inclusion and exclusion criteria. RESULTS: The 178 retrieved articles yielded 1185 mandibular distraction osteogenesis patients: 539 received unilateral mandibular distraction osteogenesis and 646 received bilateral mandibular distraction osteogenesis. Mandibular distraction osteogenesis was reported to improve facial asymmetry and retrognathia (50.1 percent), correct the slanted lip commissure (24.7 percent), and improve or level the mandibular occlusal plane (11.1 percent) in unilateral asymmetry cases, whereas bilateral mandibular distraction osteogenesis was shown to be effective in preventing tracheostomies for 91.3 percent of neonates or infants with respiratory distress, and in relieving symptoms of obstructive sleep apnea for 97.0 percent of children and 100 percent of adult patients. CONCLUSIONS: Mandibular distraction osteogenesis is effective in treating craniofacial deformities, but further clinical trials are required to assess the long-term stability and to compare the treatment with conventional treatment methods, especially in cases of obstructive sleep apnea or class II mandibular hypoplasia.

Stereomodel-assisted fibula flap harvest and mandibular reconstruction.

PURPOSE: To describe a method for stereomodel-assisted fibula flap harvest and mandibular reconstruction utilizing multiple fibula bony segments. MATERIALS AND METHODS: Stereomodels of the mandible and the fibula were obtained from computed tomography scan data. The length of fibula to be harvested was predetermined by measurement of the stimulated of existing mandibular defect on the mandibular stereomodel. A titanium reconstruction plate was shaped to fit the original mandibular contour. The stereomodel fibula was divided into multiple segments and the segments were placed on the mandibular stereomodel in the ideal edentulous position against the upper dentition and simulate the angular contour of the mandible for best comesis. The predetermined bony segments were measured and the system was then transferred to the patient in the operation theater using acrylic locating splints. RESULTS: Experience with 8 patients (2 primary and 2 secondary reconstructions) indicated that a good clinical outcome in terms of mandibular contour and positions of the reconstructed segment was possible. The outer facial appearance and symmetry were consistently excellent and no instability or malposition of the graft segments was encountered. CONCLUSION: Stereomodel-assisted fibula flap harvest and insertion is a worthwhile attempt at improving the results of mandibular reconstruction and deserves further attention.

Surgical induction of temporomandibular joint ankylosis: an animal model.

PURPOSE: The aim of this study was to develop an animal model of temporomandibular joint (TMJ) bony ankylosis for future evaluation of surgical reconstructive methods. MATERIALS AND METHODS: An animal model was selected on the basis of 2 sequential experiments. Four goats and 4 minipigs were used in the first experiment, in which 1 goat and 1 minipig served as control animals. Condylectomy with disc preservation was performed on 1 side of 3 animals in each group. On the contralateral TMJ, condylectomy with discectomy was performed, and the arthroplasty gap was filled with the autogenous bone chips. In the second experiment, TMJ ankylosis was induced bilaterally in 3 additional animals of the species that achieved better ankylosis results in the first experiment. All animals were killed postoperatively at 3 months, and the TMJ complexes were examined by plain radiography, computed tomography, and histological evaluation. RESULTS: In the first experiment, only fibrous ankylosis was observed in the bone-grafted side of 2 goats and 3 minipigs, whereas fibro-osseous ankylosis was achieved in the remaining goat. The extent of ankylosis was found to be more severe in the goats than the minipigs. Hence, goats were selected for bilateral surgery in the second experiment, which achieved consistent bony ankylosis of the TMJ in all animals. CONCLUSIONS: Goats provide a better TMJ bony ankylosis model than minipigs. Consistent bony ankylosis can be induced by bilateral condylectomy, disectomy, and bone grafting of the arthroplasty gap.

The long-term effect of transport distraction in the management of temporomandibular joint ankylosis.

BACKGROUND: The purpose of this study was to investigate the long-term effect of condylar reconstruction by transport distraction of the mandibular ramus after the release of temporomandibular joint ankylosis. METHODS: Five patients presenting with unilateral temporomandibular joint ankylosis corrected by gap arthroplasty and transport distraction of the ascending mandibular ramus were recruited for this prospective cohort study. A clinical evaluation of each case was performed longitudinally before and during the operation, during the distraction consolidation period, and 1 to 2 years after removal of the distractor. The assessment criteria included temporomandibular joint mobility and patient satisfaction expressed with reference to a visual analogue scale. RESULTS: The mean preoperative mouth opening of the five patients was 14 mm. Coronoidectomies were performed concurrently to widen the mouth opening in all cases. Maxillomandibular osteotomies were performed in three cases to correct associated dentofacial deformities. The mean mouth opening achieved during the operations was 40.4 mm. At long-term follow-up, the mean mouth opening was 38 mm, and no sign or symptom of temporomandibular joint dysfunction was noted. The mean patient satisfaction score was 8.6 of 10. CONCLUSIONS: Transport distraction of the mandibular ramus is a good treatment modality for temporomandibular joint ankylosis, particularly for adults. It can achieve long-term, symptom-free, stable mouth opening.

Psychological profile of Chinese with cleft lip and palate deformities.

OBJECTIVE: To assess the psychological well-being of patients with cleft lip and palate (CLP). PATIENTS/SETTING: Ninety-four Chinese CLP subjects between 10 and 40 years of age were recruited from the Discipline of Oral and Maxillofacial Surgery, The University of Hong Kong, between June and December 2003. They were divided into two groups for comparison: adolescents (10-16 years old) and adults (17- 40 years old). A control group of 116 healthy non-CLP patients was also recruited during the same period. INTERVENTIONS: All CLP and non-CLP patients were asked to complete a set of four questionnaires to assess their psychological status. The questionnaires included the Social Avoidance and Distress Scale, the Satisfaction with Life Scale, the Culture-Free Self-Esteem Inventory, and the Chinese Miller Behavioral Style Scale. RESULTS: Chinese CLP patients exhibited levels of subjective well-being and social anxiety that were similar to the published levels of a group of British CLP patients. They also had significantly lower general and social self-esteem but higher parental self-esteem than the non-CLP control group. CONCLUSION: CLP patients were generally satisfied with life and did not exhibit more social anxiety than the non-CLP control group. They also had a good relationship with their parents. Gender and educational level had no influence on their psychological profile. However, these CLP patients had lower self-esteem than non-CLP patients.

Evaluation of recombinant human bone morphogenetic protein-2 in mandibular distraction osteogenesis in rabbits: Effect of dosage and number of doses on formation of bone.

We evaluated the dose- and time-dependent response of recombinant human bone morphogenetic protein-2 (rhBMP-2) to the formation of bone in mandibular distraction osteogenesis. Twenty-one adult white New Zealand rabbits (3.0-3.8 kg) were used to establish the mandibular distraction model, 18 of which completed the experiment. Eight rabbits were given rhBMP-2 360 microg and eight 1080 microg; two were given no rhBMP-2. The fluids were injected into the regenerating bone at three different time sequences (days 5, 8, and 11 of active distraction; days 5 and 11 of active distraction; and day 11 of active distraction alone). After four weeks of consolidation, the specimens were harvested and examined radiographically by micro-computed tomography (micro-CT), and histologically. The formation and remodelling of bone in distraction osteogenesis was significantly increased by the addition of rhBMP-2, and the increase was dose-dependent. There was no significant difference between different dosage regimens. A single injection of rhBMP-2 at the end of the distraction phase was as effective as multiple injections.

Healing of maxillary alveolus in transport distraction osteogenesis for partial maxillectomy.

PURPOSE: This study aims to evaluate histologic healing of the new bone and soft tissue in the distraction gap of maxillary alveolus after transport distraction at different consolidation intervals. MATERIALS AND METHODS: In a monkey model, dentoalveolar segment was distracted backward to a surgical defect in the posterior maxilla with an internal distractor at a rate of 1 mm/day for 2 weeks. The distracted dentoalveolar processes were harvested at 1, 2, and 3 months of consolidation after the completion of distraction. Histologic examination included the new bone, gingiva of the distraction gap, and teeth carrying the transport segments. Tartrate-resistant acid phosphatase was used to assess the presence of osteoclasts in the new bone. The collagen type and expression of bone morphogenetic proteins (BMPs) in the new bone were assessed by immunohistochemistry. RESULTS: The histology confirmed new bone bridging the distraction gap at 1 month of consolidation. Woven bone was progressively replaced by mature lamellar bone at the second and third months. The gingiva covering the distraction gap was of normal appearance. There were no pathologic pulpal changes noted in the transport segment. Tartrate-resistant acid phosphatase-positive osteoclasts were minimal in the new bone. The mode of ossification was confirmed as intramembranous, and the fibrous stroma consisted mainly of collagen type I. At 1 month of consolidation, the BMPs were expressed profusely in the fibrous matrix and also inside the fibroblasts and osteoblasts. At 2 and 3 months of consolidation, the BMP expression intensity was reduced significantly in the fibrous stroma. CONCLUSIONS: The study confirmed that the bone regenerate in maxillary transport distraction was formed by intramembranous ossification and teeth in the transport segment remain viable after maxillary transport distraction osteogenesis.

Distraction or osteotomy for the correction of maxillary cleft deformities: which is better?

The application of distraction osteogenesis in the maxillofacial region is gaining popularity. However, it remains controversial whether distraction osteogenesis can produce better outcomes than the conventional orthognathic surgery particularly in cleft lip and palate (CLP) patients. This paper presents the two treatment methods--conventional orthognathic surgery and distraction osteogenesis in the management of maxillary hypoplasia in CLP patients. One clinical case was selected for illustration on each method. The discussion is based on the current literature focusing on the differences in indications, surgical techniques, morbidities, relapse, speech and velopharyngeal changes.