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PURPOSE: Boolean operations in computer-aided design or computer graphics are a set of operations (e.g. intersection, union, subtraction) between two objects (e.g. a patient model and an implant model) that are important in performing accurate and reproducible virtual surgical planning. This requires accurate and robust techniques that can handle various types of data, such as a surface extracted from volumetric data, synthetic models, and 3D scan data. METHODS: This article compares the performance of the proposed method (Boolean operations by a robust, exact, and simple method between two colliding shells (BORES)) and an existing method based on the Visualization Toolkit (VTK). RESULTS: In all tests presented in this article, BORES could handle complex configurations as well as report impossible configurations of the input. In contrast, the VTK implementations were unstable, do not deal with singular edges and coplanar collisions, and have created several defects. CONCLUSIONS: The proposed method of Boolean operations, BORES, is efficient and appropriate for virtual surgical planning. Moreover, it is simple and easy to implement. In future work, we will extend the proposed method to handle non-colliding components.

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The temporomandibular joints function in synergy with the dental occlusion within the manducatory system. Orthodontists and surgeons must take into account the condylar position since any problem related to positioning of the condyle could result in occlusal disorders including relapse and the risk of occurrence, decompensation or worsening of temporomandibular dysfunction. We wanted to answer three questions: What is the position of the condyle following orthognathic surgery? What benefit is there in repositioning the condyle? What means are available to check condylar position? Finally, in the light of the answers, we describe an innovative occlusal and condylar positioning device for mandibular osteotomies based on computer-assisted surgical planning techniques. It consists of a three-dimensional, printed guide enabling surgeons to position the condyles as desired. It is accurate, simple, reproducible, independent of operator experience as well as rapid and economical.

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AIMS: Clinicians increasingly suggest assessment and treatment of the cervical spine in patients with temporomandibular dysfunction (TMD); however, few studies have investigated upper cervical spine mobility in people who suffer from TMD. The purpose of this study was to investigate whether patients with TMD pain (with or without headache) present with upper cervical spine impairment when compared with asymptomatic subjects. METHODOLOGY: A single blind examiner evaluated cervical range of motion (ROM) measures including axial rotation during the flexion-rotation test (FRT) and sagittal plane ROM. Twenty asymptomatic subjects were compared with 37 subjects with pain attributed to TMD, confirmed by the Revised Research Diagnostic Criteria. Subjects with TMD were divided according to the presence of headache (26 without headache TMDNHA, 11 with headache TMDHA). One-way analysis of variance and planned orthogonal comparisons were used to determine differences in cervical mobility between groups. All subjects with TMD were positive on the FRT with restricted ROM, while none were in the control group. RESULTS: The analysis of variance revealed significant differences between groups for the FRT F(2,54) = 57.96, P<0.001) and for sagittal ROM [F(2,54) = 5.69, P = 0.006]. Findings show that the TMDHA group had less axial rotation than group TMDNHA, and both TMD groups had less ROM than controls. For sagittal ROM, the only difference was between group TMDHA and controls. CONCLUSIONS: Subjects with TMD had signs of upper cervical spine movement impairment, greater in those with headache. Only subjects with TMD and headache had impairment of cervical spine sagittal plane mobility. This study provides evidence for the importance of examination of upper cervical mobility determined by the FRT in patients who suffer from TMD.

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PURPOSE: The different surgical approaches used to treat mandibular condyle fractures are carried out in the periparotid skin area and can lead to facial nerve injury. We conducted a preauricular and anteroparotid surgical approach. Our main aim was to show the anatomical relationship between this approach site and the facial nerve branches, and to define cutaneous landmarks to locate the extraparotid facial nerve branches. METHOD: A 2-step dissection of 13 fresh human cadaver semi-heads was performed: a preauricular approach followed by a superficial parotidectomy to visualize the facial nerve. Its course and ramifications were studied and compared to cutaneous landmarks. The proximity of the facial nerve branches with the surgical approach site was observed. RESULTS: The approach allowed systematically visualising the zygomatic and/or buccal branches. No facial nerve branches were sectioned. In three cases (23 %), a nerve branch was visualized during the approach. The buccal and zygomatic branches were ramified in 77 % of cases. CONCLUSIONS: During our preauricular anteroparotid approach, the buccal and zygomatic branches were visualized but none was sectioned. Most often the approach was carried out between these two branches (46 % of cases). Cutaneous landmarks used were reliable to define a safe and nerve-free area for dissection. The buccal and zygomatic branches are very interesting because their high number of ramifications and anastomoses could serve as nerve relays in case of surgical lesion.

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PURPOSE: Inadequate bone width in atrophic edentulous jaws is a challenge for successful oral rehabilitation with endosseous dental implants. The aim of this clinical study was to evaluate the effectiveness of a new method for ridge expansion with sagittal splitting using a new surgical device (Crest-Control Bone Splitting System, Meisinger) and to determine whether it is necessary to fill the expansion area with bone substitute to maintain the expanded bone volume. MATERIALS AND METHODS: During a 3-year period, a prospective study was performed in 32 patients (59% women, 41% men). All participants needed implants in the horizontally atrophied edentulous mandible and were treated in a private practice and a hospital. The only inclusion criteria were a mandibular ridge width between 3 and 4 mm and ridge height of at least 11 mm. Expansion with horizontal splitting of the ridge was performed simultaneously with implant placement. In 17 of the 32 arches, selected alternately, the expanded ridges were filled with a biphasic calcium phosphate (hydroxyapatite 60% and beta-tricalcium phosphate 40%) synthetic bone substitute (SBS 60/40). The other 15 expanded arches were left unfilled. All areas were covered with a resorbable collagen membrane (Bio-Gide, Geistlich). Results were analyzed with the Mann-Whitney and Kruskal-Wallis tests (α=.05). RESULTS: There was a significant difference (α=.02) between the patients who received SBS 60/40 (17 cases) and those who did not (15 cases). The ridges that received SBS 60/40 after expansion showed no bone resorption. CONCLUSION: Horizontal expansion of the ridge is easily reproducible. In this study, in very narrow ridges, a lack of bone substitute resulted in significant resorption of 3- to 4-mm-wide crests (5%), even after expansion. A bone substitute should be placed to maintain the alveolar bone walls after expansion.

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AIM: We decided to study the relationship between brain volume and cranial capacity and the relationship between brain volume and age on a series of CT from healthy adults. METHODS: Fifty-eight healthy volunteers (27 women, 31 men, age range 18-95 years) were examined using our imaging protocols. The volunteers had no present or past neuropsychiatric illness and no abuse of alcohol or illicit drugs. RESULTS: Mean intracranial volume was 1,384.6 cm(3) (standard deviation = 135.27, range 1,106-1,656) and mean brain volume was 1,201.0 cm(3) (standard deviation = 142.52, range 791-1,500). Linear regression between brain volume and cranial capacity yielded this formula: brain volume = 182.3 + 0.7 × cranial capacity. Multivariate analysis yielded a relationship between cranial capacity, brain volume and age as follows: brain volume = 396.5-3.5 × age + 0.7 × cranial capacity. CONCLUSION: This study could be supplemented by the collection of data such as, the size of the individuals in order to study the relationship between size of the brain and stature because this relation remains unclear.

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PURPOSE: In our Bordeaux maxillofacial surgery unit, we have used the Michelet technique described for 40 years: manual fracture reduction and semi-rigid miniplate osteosynthesis fixation. No maxillomandibular fixation (MMF) with arch bars or with screws was used for reduction during osteosynthesis. The aim of this work was to evaluate results of this unknown manual reduction method. MATERIALS AND METHODS: A total of 184 patients were reviewed. We recorded epidemiology of mandible fracture, clinical and radiologic evaluation before and after surgery, and treatment. Anatomic and functional manual reductions were the basic principle: manual maxillomandibular immobilization (functional) and manual fracture reduction (anatomic). In cases of condylar fractures without severe displacement, MMF with cortical bone screws was indicated (orthopedic treatment). Physiotherapy was also possible (functional treatment). RESULTS: In all, 315 mandible fractures sustained by 184 patients were reviewed into the study. Of the patients, 80% were treated by osteosynthesis: 54% by osteosynthesis treatment alone, 26% by osteosynthesis and orthopedic treatments. The average time required for osteosynthesis or osteosynthesis and orthopedic treatment was 56 minutes. We observed 0.67% of disturbed occlusion, 0.67% of pseudarthrosis, and 0.67% of bilateral temporomandibular joint internal derangement. CONCLUSIONS: Manual fracture reduction suppresses systematic MMF using arch bars during osteosynthesis of mandible fractures. Operating time and risk of complications are reduced. Functional results seem to be similar to that reported in the literature.

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PURPOSE: Treatment of mandibular condylar fractures is not standardized. The maxillomandibular cortical bone screw fixation technique carries many advantages. The aim of this work was to evaluate this technique for routine method. MATERIALS AND METHODS: Fifty patients treated by maxillomandibular fixation (MMF) by use of cortical bone screws from 2004 to 2006 were retrospectively analyzed. In our maxillofacial surgery unit in Bordeaux, France, our indication is to treat extra-articulated fractures without severe displacement by MMF. RESULTS: The mean time required for MMF was 13 minutes, and fixation occurred after a mean of 16 days. Screw removal was performed after a mean of 26 days, and this required local anesthesia. Of the patients, 48 had good occlusion. Two patients had persistent lateral cross bites. Two patients had mandible deviation when they opened their mouths, and mouth opening was limited in one patient. Two patients had temporomandibular joint pain. CONCLUSIONS: MMF screws have more advantages and fewer disadvantages than arch bars when closed treatment has been selected as the treatment of choice.

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