• Korean Journal of Cognitive Science
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• v.18 no.4
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• pp.445-455
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• 2007

We present a new biometric identification system based on multi-view features of teeth using principal components analysis(PCA). The multi-view features of teeth consist of the frontal view, the left side view and the right side view. In this paper, we try to stan the foundations of a dental biometrics for secure access in real life environment. We took the pictures of the three views teeth in the experimental environment designed specially and 42 principal components as the features for individual identification were developed. The classification for individual identification based on the nearest neighbor(NN) algorithm is created with the distance between the multi-view teeth and the multi-view teeth rotated. The identification performance after rotating two degree of test data is 95.2% on the left side view teeth and 91.3% on the right side view teeth as the average values.

• Restorative Dentistry and Endodontics
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• v.24 no.1
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• pp.55-66
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• 1999

The purpose of this study was to evaluate the microleakage of 5 current dentin bonding systems which are composed of 2 multi-bottle systems(Scotchbond Multi-Purpose, All Bond2) and 3 one-bottle systems(Single bond, One-Step, Prime & Bond). In this in vitro study, class V cavities were prepared on buccal and lingual surfaces of sixty extracted human premolars and molars on cementum margin. The experimental teeth were randomly divided into six groups of 10 samples (20 surfaces) each, Group 1 : Scotchbond Multi-Purpose ; Group 2 : All Bond 2 ; Group 3 : Single Bond ; Group 4 : One-Step ; Group 5 : Prime & Bond ; Group 6 : no bonding agent(control). The bonding agent and composite resin were applied for each group following the manufacturer's instructions. After 500 thermocycling between $5^{\circ}C$ and $55^{\circ}C$, the 60 teeth were placed in 2% Methylene blue dye for 24 hours, then rinsed with tab water. The specimen were embedded in clear resin, then sectioned buccolingually through the center of restoration with a low speed diamond saw. The dye penetration on each of the specimen were then observed with a stereomicroscope at ${\times}20$. The results of study were statistically analyzed using the Student-Newmann-Keul's Methods and the Mann-Whitney Rank Sum Test. The resin/dentin interfaces were examined under Scanning Electron Microscopy. The results of this study were as follows. 1. None of the dentin bonding systems used in this study showed significant difference in leakage values at both the enamel and the dentin margins (P>0.05). 2. In all groups except the control, leakage value seen at the enamel margin was significantly lower than that seen at the dentin margin (P<0.05). 3. Compared to the control group, all the groups treated with dentin bonding systems showed significantly lower leakage value at both enamel and dentin margins (P<0.05). 4. In the SEM view, gaps were observed in the composite resin / dentin interface in group 6 where no dentin bonding agent was used, and in all the other groups (group 1, 2, 3, 4, 5) composite resin, hybrid layer, and dentin were seen to be closely adhering to each other where there were no leakages. Well-developed resin tags 3~100${\mu}m$ in length infiltrated dentinal tubules past the hybrid layer and a hybrid layer 1~5${\mu}m$ thick had developed between the dentinal surface and the composite resin surface.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.39
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• pp.13.1-13.8
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• 2017

Background: Oronasal/antral communication, loss of teeth and/or tooth-supporting bone, and facial contour deformity may occur as a consequence of maxillectomy for cancer. As a result, speaking, chewing, swallowing, and appearance are variably affected. The restoration is focused on rebuilding the oronasal wall, using either flaps (local or free) for primary closure, either prosthetic obturator. Postoperative radiotherapy surely postpones every dental procedure aimed to set fixed devices, often makes it difficult and risky, even unfeasible. Regular prosthesis, tooth-bearing obturator, and endosseous implants (in native and/or transplanted bone) are used in order to complete dental rehabilitation. Zygomatic implantology (ZI) is a valid, usually delayed, multi-staged procedure, either after having primarily closed the oronasal/antral communication or after left it untreated or amended with obturator. The present paper is an early report of a relatively new, one-stage approach for rehabilitation of patients after tumour resection, with palatal repair with loco-regional flaps and zygomatic implant insertion: supposed advantages are concentration of surgical procedures, reduced time of rehabilitation, and lowered patient discomfort. Cases presentation: We report three patients who underwent alveolo-maxillary resection for cancer and had the resulting oroantral communication directly closed with loco-regional flaps. Simultaneous zygomatic implant insertion was added, in view of granting the optimal dental rehabilitation. Conclusions: All surgical procedures were successful in terms of oroantral separation and implant survival. One patient had the fixed dental restoration just after 3 months, and the others had to receive postoperative radiotherapy; thus, rehabilitation timing was longer, as expected. We think this approach could improve the outcome in selected patients.

• Restorative Dentistry and Endodontics
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• v.27 no.4
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• pp.421-431
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• 2002

C-shaped canal configuration is very difficult to treat because that clues about preoperative canal anatomy cannot be ascertained from clinical crown morphology and limited information can be derived from radiographic examination. This study was done to get more informations about the root and canal configuration of C-shape root by 3-dimensionally reconstructing for the purpose of enhancing success rate of endodontic treatment. 30 mandibular molars with C-shaped root were selected. Six photo images from occlusal, apical, mesial, distal, buccal, lingual directions and radiographic view were taken as preoperative ones to compare them with 3-D image. After crown reduction to the level of 1-2mm over pulpal floor was performed, teeth were stored in 5.25% sodium hypochlorite solution for the removal of pulp tissue and debris. They were cleaned under running water, allowed to bench dry and embedded in a self-curing resin. This resin block was serially ground with a microtome (Accutom-50, Struers, Denmark) and the image of each level was recorded by digital camera (FinePix S1-pro, Fuji Co., Japan). The thickness of each section was 0.25mm. Photographs of serial sections through all root canal were digitized using Adobe Photoshop 5.0 and then minimum thickness of open and closed sites were measured (open site is the surface containing occluso-apical groove closed site is oppsite). After dizitization using 3-D Doctor (Able software Corp, USA). 3D reconstruction of the outer surface of tooth and the inner surface of pulp space was made. Canal classsification of C-shaped roots was performed from this 3-D reconstructed image. The results were as follows : 1. Most C-shape rooted teeth showed lingual groove (28/30). 2 According to Vertuccis' calssification, type I, II, III, IV, VII were observed. but also new canal types suck as 2-3-2, 1-2-3-2. 2-3-2-1, 2-3-2-3 were shown. 3 There was little difference in minimum thickness on coronal and apical portions, but open site were thinner than closed site on mid portion. Conclusively, 3D reconstruction method could make the exact configurations of C-shape root possible to be visualized and analyzed from multi-directions. Data from minimum thickness recommend cleaning and shaping be more carefully done on dangerous mid portion.