Evaluation of bone thickness around the mental foramen for potential fixation of a bone-borne functional appliance: a computer tomography scan study.

AIM: A mandible bone-borne Herbst appliance (MBBHA) would avoid the proclination of the lower incisors that occurs with any teeth-borne functional appliance. But mapping of the bone characteristics at potential fixation areas around the mental foramen has not been carried out so far. The aim of this computer tomographic (CT) study was to evaluate bone thickness at specific positions around the mental foramen. MATERIAL AND METHODS: CT scans of 60 randomly chosen adult Hong Kong Chinese subjects (mean age 28 ± 6.3 years) were used to measure the bi-cortical bone thickness in the mandible in the mental foramen area. The thickness of buccal and lingual cortical and cancellous bone was assessed at the following locations: 10 mm (A10 mm) and 5 mm (A5 mm) anterior, 10 mm (P10 mm) and 5 mm (P5 mm) posterior, and 5 mm (Inf5 mm) below the mental foramen. RESULTS: The amount of buccal cortical bone thickness ranged between 1.89 mm, 10 mm anterior of the mental foramen, and 2.16 mm, 10 mm posterior to its location. At the A10 mm level, cortical thickness showed a marginal statistically significant difference between A5 and A10 mm. The total amount of bone thickness ranged from 10.19 to 12.06 mm. CONCLUSION: At the locations studied around the mental foramen, a mean bicortical bone thickness of 10-12 mm was measured. No large variation in the thickness was found between bicortical bone thicknesses in the measured locations around the mental foramen. Thorough evaluation on a case-by-case basis is advisable.

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.

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.

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.

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.

Dental implants in reconstructed jaws: patients' evaluation of functional and quality-of-life outcomes.

PURPOSE: To evaluate the quality-of-life aspect of treatment outcome following functional jaw reconstruction and dental implants in the maxilla or mandible. MATERIALS AND METHODS: This cross-sectional study used a questionnaire interview of 28 rehabilitated patients who received autogenous bone grafts from the ilium and endosseous implants (14 maxillary and 14 mandibular cases; 134 implants) for functional jaw reconstruction between 1988 and 1999. A questionnaire was developed to assess the quality-of-life outcome for those patients who had finished their rehabilitation at least 6 months prior to the interview. Responses to the questions were recorded by means of visual analog scales. RESULTS: In general, patients gave positive comments on the restoration of their orofacial appearance and function (mastication and speech). The majority (85.7%) found no problem in various daily social activities, including dining in public. DISCUSSION: The overall level of satisfaction with the treatment outcome and the degree of recommendation of the treatment to others were both favorable (mean scores 8.6 and 8.7 out of 10, respectively). CONCLUSION: Oral rehabilitation using functional jaw reconstruction can reach a satisfactory level of esthetics, function, and psychosocial well being of patients, thus improving their quality of life.

Stability consideration for internal maxillary distractors.

PURPOSE: Stability in distractor design ensures distraction osteogenesis healing with good bone regenerate formation. The aim of this study was to compare the holding strengths of different fixation systems for maxillary distractor design on bone pieces of different thicknesses. MATERIAL AND METHODS: Cross-sectional images of 10 dry skulls were obtained by computer tomography and the bone thickness of the maxillae were measured according to five individual anatomical regions (paranasal, infra-orbital, posterior sinus wall, zygomatic and alveolar regions). According to the measurements, the screws of 1.5 and 2mm in diameter and the three-screw mini-plates in triangular and straight configurations were evaluated for holding strength by pull-out tests on fresh animal bone pieces of defined thickness. RESULTS: The paranasal and zygomatic regions of the human skulls had the thickest cortical bone (4mm) followed by the alveolar region (2mm). In the bones of 2 and 4mm thickness, the 2mm screws were confirmed stronger than the 1.5mm ones in pull-out tests. However, the pull-out behaviour of screws of different diameters in 1mm thick bones and the mini-plates in two different configurations showed no significant differences. CONCLUSION: This study confirms that the paranasal and zygomatic bones are the thickest for fixation of internal maxillary distractors. Fixation screws of 2mm diameter in either triangular or straight miniplates can produce good stabilization for distractors.

Radiologic characterization of new bone generated from distraction after maxillary bone transport.

OBJECTIVE: The purpose of this study was to characterize the radiologic features of the new bone generated from distraction following maxillary bone transport. STUDY DESIGN: Maxillary dentoalveolar segments were transported by distraction to close posterior maxillectomy defects in 9 rhesus monkeys. The distracted dentoalveoli were harvested at 1, 2, 3, and 6 months after the completion of the distraction. The specimens were evaluated by plain radiography and microcomputerized tomography scanning, which included 2- and 3-dimensional quantitative analyses of bone regeneration volume and microstructural indices. RESULTS: Plain radiographs showed that radiolucency in the distraction regenerate reduced with time. Microcomputerized scanning found that bone formation and trabecular thickness increased in the new bone with longer consolidation. The high orientation and connectivity of the trabeculae were reduced at longer consolidation intervals. Within the whole distraction gap, bone volume was found to be site-specific. CONCLUSION: Morphologic analysis in the high resolution offered by microcomputerized tomography shows that active bone mineralization and remodeling occur in the new bone within 3 months after distraction in maxillary dentoalveolus.

A survey on Hong Kong secondary school students' knowledge of emergency management of dental trauma.

OBJECTIVES: To investigate Hong Kong secondary school students' knowledge of emergency management of dental trauma. METHOD: A questionnaire survey on randomly selected secondary school students using cluster sampling. RESULTS: Only 36.6% (209/571) of the respondents were able to correctly identify the appropriate place for treatment of dental injury. 55.2% of the respondents knew the suitable time for treatment. Only 24.7% of the respondents possessed the knowledge of how to correctly manage fractured teeth. Only 23.6% of them knew how to manage displaced teeth. 62.5% of them correctly answered that knocked-out deciduous teeth should not be replanted to the original position, but few of them (23.6%) knew that permanent teeth should be replanted. Moreover, 37.1% of the respondents correctly identified at least one of the appropriate media for storing a knocked-out tooth. First-aid training and acquisition of dental injury information from other sources were significant factors that positive responses from these questions would lead to higher scores. CONCLUSION: Hong Kong secondary school students' knowledge of emergency management of dental trauma is considered insufficient. An educational campaign in secondary schools dedicated to students is recommended. Prior first-aid training and acquisition of dental injury information from other sources positively relate to the level of knowledge. Dental trauma emergency management is recommended to be added to first-aid publications and be taught to students and health professionals. TRIAL REGISTRATION: Hong Kong Clinical Trial Centre HKCTR-1344.

Effectiveness of educational poster on knowledge of emergency management of dental trauma--part 2: cluster randomised controlled trial for secondary school students.

OBJECTIVE: To investigate the effectiveness of educational poster on improving secondary school students' knowledge of emergency management of dental trauma. METHODS: A cluster randomised controlled trial was conducted. 16 schools with total 671 secondary students who can read Chinese or English were randomised into intervention (poster, 8 schools, 364 students) and control groups (8 schools, 305 students) at the school level. Baseline knowledge of dental trauma was obtained by a questionnaire. Poster containing information of dental trauma management was displayed in a classroom for 2 weeks in each school in the intervention group whereas in the control group there was no display of such posters. Students of both groups completed the same questionnaire after 2 weeks. RESULTS: Two-week display of posters improved the knowledge score by 1.25 (p-value = 0.0407) on average. CONCLUSION: Educational poster on dental trauma management significantly improved the level of knowledge of secondary school students in Hong Kong. TRIAL REGISTRATION: HKClinicalTrial.com HKCTR-1343 ClinicalTrials.gov NCT01809457.

Effectiveness of educational poster on knowledge of emergency management of dental trauma-part 1. Cluster randomised controlled trial for primary and secondary school teachers.

OBJECTIVE: To investigate the effectiveness of educational posters in improving the knowledge level of primary and secondary school teachers regarding emergency management of dental trauma. METHODS: A cluster randomised controlled trial was conducted. 32 schools with a total of 515 teachers were randomised into intervention (poster) and control groups at the school level. Teachers' baseline levels of knowledge about dental trauma were obtained by using a questionnaire. Posters containing information on dental trauma management were displayed in the school medical room, the common room used by staff, and on a notice board for 2 weeks in each school of the intervention group; in the control group, no posters were displayed. Teachers in both groups completed the questionnaire after 2 weeks. RESULTS: The teachers in the intervention schools (where posters were displayed for 2 weeks) showed statistically significant improvement in scores in cases where they had not previously learned about dental emergencies from sources other than first aid training, with an average score increase of 2.6656 (score range of questionnaire, -13 to 9; p-value <0.0001). CONCLUSION: Educational posters on the management of dental trauma can significantly improve the level of knowledge of primary and secondary school teachers in Hong Kong. KClinicalTrials.com HKCTR-1307 ClinicalTrials.gov: NCT01707355.

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.

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.

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.

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.

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.

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.

The long-term clinical morbidity of mandibular step osteotomy.

The objectives of this retrospective study were to assess the clinical applications of mandibular step osteotomy (MSO) and to evaluate its long-term clinical morbidities. A total of 152 patients with MSO performed between 1990 and 1999 were assessed. Forty-two patients were successfully recalled through questionnaires and clinical parameters for clinical evaluation, which included (1) tooth sensibility; (2) periodontal status; (3) neurosensory deficit in terms of light-touch threshold, 2-point discrimination, and pain threshold; and (4) temporomandibular joint function. The patients were finally asked about their overall satisfaction with the surgical treatment. The result revealed that MSO was commonly indicated for the correction of mandibular hyperplasia. Clinical assessments showed that 2.75% of the teeth assessed had negative pulpal response, 3.9% showed mildly increased probing depth, and another 3.9% showed gingival recession. Neurosensory assessment revealed that 31% of the operating sites had an increased light-touch threshold, 4.8% had heightened 2-point discrimination, and 9% had an elevated pain threshold. Also, 9.7% of the patients showed reduced mouth opening and 17% had mild tenderness of masticatory muscles. Of all the patients assessed, 12% were not satisfied with the orthognathic treatment. The reasons included relapse, residual asymmetry, and persistent paresthesia.