Purpose Quantification of teeth is of clinical importance for various computer assisted procedures such as dental implant, orthodontic planning, face, jaw and cosmetic surgeries. In this regard, segmentation is a major step. Methods In this paper, we propose a method for segmentation of teeth in volumetric computed tomography (CT) data using panoramic re-sampling of the dataset in the coronal view and variational level set. The proposed method consists of five steps as follows: first, we extract a mask in a CT images using Otsu thresholding. Second, the teeth are segmented from other bony tissues by utilizing anatomical knowledge of teeth in the jaws. Third, the proposed method is followed by estimating the arc of the upper and lower jaws and panoramic re-sampling of the dataset. Separation of upper and lower jaws and initial segmentation of M. Hosntalab (B) · A. Abbaspour Tehrani-Fard teeth are performed by employing the horizontal and vertical projections of the panoramic dataset, respectively. Based the above mentioned procedures an initial mask for each tooth is obtained. Finally, we utilize the initial mask of teeth and apply a Variational level set to refine initial teeth boundaries to final contours. Results The proposed algorithm was evaluated in the presence of 30 multi-slice CT datasets including 3,600 images. Experimental results reveal the effectiveness of the proposed method. Conclusion In the proposed algorithm, the variational level set technique was utilized to trace the contour of the teeth. In view of the fact that, this technique is based on the characteristic of the overall region of the teeth image, it is possible to extract a very smooth and accurate tooth contour using this technique. In the presence of the available datasets, the proposed technique was successful in teeth segmentation compared to previous techniques.

Epidemiologic study, level IV.

Aim:This study was designed to assess the prevalence, distribution, and patterns of injury among athletes engaged in combat sports and compare the prevalence, pattern, and types of oral and maxillofacial trauma in these athletes.Materials and Methods:A total of 120 male athletes engaged in four combat sports (boxing, taekwondo, kickboxing, and Muay Thai) who had sustained bodily trauma were studied; 95 subjects with at least one traumatic injury to the face requiring treatment were referred to us by the physician team. The type of injury (facial laceration, facial fractures, jaw dislocation, etc.), site of facial injury (jaw, nose, malar bone, teeth, etc.), dental injuries (tooth fracture, displacement, luxation, and avulsion), causative sport (boxing, taekwondo, kickboxing, and Muay Thai) as well as demographic data were recorded. Injuries were examined clinically and radiographically, and treated accordingly by a specialist. Treatment data and demographics were recorded for each subject. Recorded data were assessed, and χ2, ANOVA, and Kruskal–Wallis tests were used to statistically analyze and compare the data.Results:Of 120 subjects, 95 male subjects (79.2%), aged 18–25 years (avg. 20 years), had at least one traumatic injury to the face requiring medical treatment. These injuries included facial laceration, bone fractures (nose, mandible, and zygoma), dental injuries (displacement, luxation, fracture, and avulsion), and mandibular dislocation which were recorded in 83 (69.2%), 55 (45.1%), 53 (44.2%), and 8 (6.7%) cases respectively. Statistically significant differences were encountered among various injuries and the sports; kickboxing caused the most maxillofacial injuries and was identified as more injurious. Tooth fractures (59.7%) were the most common dental injuries, and the nose (84.7%) was the most frequently fractured facial bone. Lacerations were more common in Thai-boxers (93.3%). Injuries were significantly greater in professional rather than amateur athletes.Conclusion:In this study, prevalence of facial injuries from combat sports professionals was significantly high (roughly 80%), especially in kickboxing (in part due to use of less protective gear). Because the nose and teeth sustained the most injuries, they require more attention with regard to prevention. Kickboxing was the most injurious of these combat sports and caused the most significant number of maxillofacial trauma. More safety apparel and protective guards seem warranted in athletes of combat sports if facial injury is to be prevented.

The study assessed the need for revision surgery and the relating factors in alveolar cleft autogenous bone grafting in patients with complete cleft. It was a retrospective study carried out in 2009. The medical records of the 54 patients with alveolar cleft who underwent autogenous bone grafting in the maxillofacial department in Shariati Hospital from 2005 to 2008 were studied. The patients' age, sex, cleft type, age at palatal and alveolar clefts repair, tooth missing, surgery turn, and presence of orthodontic treatment were assessed. The patients' alveolar bone height was evaluated from their postoperative and follow-up panoramic radiographs. In general, 41% (n = 22) of patients needed revision surgery. Among all patients, 20 (37%) had secondary bone grafting and 34 (63%) had tertiary bone grafting. For 77% of the secondary unilateral clefts and 71% of bilateral ones, the remaining bone was at least three-fourths of the normal. Logistic regression model controlling for grafting time, surgery turn, orthodontic supervision, and age at palatal cleft closure showed that orthodontic treatment is associated with a lower need for revision surgery (odds ratio = 0.3; 95% confidence interval, 0.1-1.0). In conclusion, although alveolar cleft bone grafting is necessary for the reconstruction of the complete clefts, all these patients must be under the supervision of orthodontists to benefit from the surgical treatment.

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We provided an integrated solution for teeth classification in multi-slice CT datasets. In this regard, suggested segmentation technique was successful to separate teeth from each other. The employed WFD approach was successful to discriminate and numbering of the teeth in the presence of missing teeth. The solution is independent of anatomical information such as knowing the sequence of teeth and the location of each tooth in the jaw.

PURPOSEThe purpose of this study was to achieve more retention and stability and to delay or prevent screw loosening.MATERIALS AND METHODSTwenty implants (Implantium 3.4 mm, Dentium, Seoul, Korea) were divided into 2 groups (n = 20). In the first group, an adhesive material was applied around the screw of the abutments (test group). In the second group, the screws are soaked in saliva (control group). All the screws were torqued under 30 N/cm, Then, the samples were gone through a cyclic fatigue loading process. After cyclic loading, we detorqued screws and calculated detorque value.RESULTSIn comparison with the control group, all the implant screws in the test group were smeared with the adhesive material, showing significant higher detorque value.CONCLUSIONThere are significantly higher detorque values in the group with adhesive. It is recommended to make biocompatible adhesive to reduce screw loosening.