Titanium is a promising metal in a prosthetic field and one of the application is the metal frame work for veneering with resin composites. However, there is little information on the reconstruction of retention beads on titanium castings that is a practical structure to bond resin composites on conventional metal frameworks. Therefore, in this study reconstruction of retention beads on titanium castings was examined by preparing castings using commercial investments and a casting machine.
Three sizes of retention beads (Average particle sizes : 600,200,100μm) were adhered on thin wax sheets (12×12×0.3 mm in thickness) and invested with two commercial investments for titanium (Magnesia-based investment and Magnesia-alumina-based investment). After the molds were fired according to the manufacturer's instruction, titanium (JIS grade 2) was cast into the mold using a commercial arc melting centrifugal casting machine with a rotational speed 3000 rpm. Castability of the wax patterns and reconstruction of fine retention beads were evaluated macroscopically and the contamination on the surface of the castings was evaluated by SEM and Raman spectroscopy.
The structure of retention beads prepared on the wax pattern was successfully reconstructed on the titanium castings obtained from both molds by a centrifugal casting method. However, SEM observation and Raman spectroscopy indicated that investment material still remained on the surface of the castings among the retention beads even after sandblasting. Especially, cast titanium surface with bigger beads had a larger contamination from investment than that with smaller beads. Therefore, we need other tail treatments on titanium castings to remove contamination from investment or we suggest to use an alternative method such as a non-retention beads method to apply titanium for veneered crowns.

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Tooth dimensions in Filipinos were investigated using odontometric methods. Materials used were dental casts taken from Tagalog males living in Manila, the Philippines. Casts of Japanese were measured as comparative data. Mesiodistal and buccolingual crown diameters were measured for each of the 14 teeth of permanent dentition using a digital caliper (0.01 mm).
1. Comparison between Filipinos and Japanese dentition : The mesiodistal crown diameters of the incisors were smaller in Filipinos than in Japanese, but the buccolingual diameters were larger. The canines and premolars were larger in Filipinos than in Japanese, but the molars were smaller in Filipinos. Crown indices showed that the Filipinos had relatively larger buccolingual diameters than Japanese with the exception of the premolars.
2. Comparison with other Mongoloid populations : Southeast Asian sundadonts including Filipinos had larger tooth dimensions than the typical sundadonts, such as Jomon natives and their lineage, but the shapes in sundadonts were similar. Regarding tooth shape, the reduction index in the molars effectively divided the sundadont and sinodont dental groups.

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By using commercial dentifrices for sensitive teeth, automatic two-dimensionally rotated toothbrushing was performed on the tangential ground surfaces of human sound dentin in the cervical regions for 10 min in vitro. The dentin surfaces were observed with scanning electron and scanning laser microscopes. The brushing caused remarkable abrasion with the traces of toothbrush bristles on account of the abrasive agents, while most of the dentinal tubules were occluded with dentin sludge or covered with smear layers. Therefore, daily toothbrushing with such dentifrices will promote the formation of wedge-shaped defects in the cervical regions, even if the dentin hypersensitivity is decreased temporarily due to the occlusion of the exposed tubules.

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Muscle/periosteal flaps were raised and 4.5-mm defects were created bilaterally in the tibiae of 12 rabbits. On the test side, Polyglactin 910 woven mesh was placed over the defect and the flaps were sutured. The defect on the contralateral side served as a control. After healing periods of 4 days, 1, 2, 4, 8 and 13 weeks the animals were killed, and 15-μm, hematoxylin and eosin-stained, undecalcified sections were prepared and examined. By 8 weeks postoperatively the mesh-covered defect had thoroughly healed with new bone, whereas the control showed discontinuous new bone in the defect. The mesh had been completely absorbed. The results indicate that the mesh guides bone regeneration during the early stages of healing and is eventually absorbed.

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The three-dimensional organization of collagen fibrils in the rat temporomandibular joint disk and its relationship to development of rat occlusion were investigated with scanning electron microscopy. In the articular surface of the temporomandibular joint disk in 1-week-old rats, the fibrils were irregularly interlaced with each other. At 6 weeks of age fibril bundles oriented anteroposteriorly or lateromedially appeared in association with a predominant fibril network. In rats over the age of 11 weeks, thick fibril bundles covered with the fibril network were organized in a layered manner parallel to the articular surface. The bundles were oriented lateromedially in the anterior and posterior bands of the disk and anteroposteriorly in the intermediate zone of the disk. Since the molars in rats entirely erupted at 6 weeks, the appearance of the bundles suggests incorporation of biomechanical resistance to tensile and abrasive stresses into mobile organization such as a fibril network. At 110 weeks wavy wrinkles composed of a dense network of fibrils and rotatory fibril bundles occurred in the lower articular surface of the disk. These seem to result from submitting to excessive tear and wear on the articular surface.

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Oral movement trajectories in a denture wearer were studied to evaluate the masticatory capability by monitoring orofacial movements during mastication of a colordeveloping chewing gum. The subject was an edentulous patient who had 4 dental implants in the mandible to anchor a mandibular overdenture.
Cordless, retroreflective markers that were recorded as reflective points with a clear outline when illuminated by a cold spotlight were attached to multiple reference points to monitor the orofacial movements. While chewing, the face markers on the subject were recorded on videotape using 2 high-speed TV cameras from the frontal and lateral perspectives. At the end of every 50 strokes, the color of the chewing gum was assessed using a Chroma Meter (CR-300, Minolta Co.) for the degree of redness or a* value. The same piece of chewing gum was chewed continuously for a total of 100 strokes.
The videotape recording of the start of the first period (1F) and the end of each period (1L-2L) were reproduced and fed into an image processor (Image Data, ID-8000). The movements of each marker were automatically tracked, and the resulting data of the 3-dimensional coordinates were reconstructed.
The trajectory of each monitored point during 16-sec intervals in each period was computed using a 3-dimensional analyzer (Movias 3D) with reference to the following parameters : total length from the start to finish of the trajectory (TL); distance between the start and finish of the trajectory (SL); TL to SL ratio (T/S); volume of the rectangular solid encompassing the entire trajectory (Cub); the 3-dimensional angles created by differences in the direction of the preceding and subsequent trajectories at each measured time (TH); and velocity (V).
Results : The trajectories of the incisal point (IP) and the menton (Me) were similar in shape. However, in the occluding phase, the Me moved anteriorly and superiorly beyond the position at the centric occlusion. The TL, SL, and V of both the IP and Me increased from 1F to 2L, while the Cub and TH decreased. These findings indicate that as mastication proceeds, the range of mouth movements in the closing phase becomes narrower and that all trajectories become smoother and more convergent.

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In order to remold or reconstitute the absorpted or defected bone tissue in the prosthodontic region, application of various materials have been tested. Bone morphogenetic protein (BMP) is an important bioactive protein. When only BMP was implanted to the animal muscle in vivo, little bone formation was recognized, because BMP was diffused in muscle. But the complex of carrier and BMP showed bone formation. Therefore various researcher have reported considerable materials as a carrier. In this study we employed squalane, TZ oil, liquid paraffin, Translagen (artificial dermis), and human type IV collagen as carrier of BMP. Gelatin capsules confining carriers and recombinant human bone morphogenetic protein (rhBMP) complex were surgically placed on either side of the ventral thoracic region in 4 weeks-old male Sprague-Dawley rats. Explants were removed at 14 days and evaluated soft X-ray and light microscopic examination. Histological and X-ray examination revealed new bone and marrow formation with using of every carrier and rhBMP complexes. However, none was apparent in only carriers as a negative control.
From five type carriers, Type IV collagen-rhBMP complex showed the widest bone formation with marrow tissue (ca 4×3 mm size at the X-ray observation), and other three oily materials (squalane, TZ oil, liquid paraffin) also showed the bone formation but, their sizes (ca 2×1 mm) were smaller than that of Type IV collagen-rhBMP complexes. and Translagen (artificial dermis) was showed only weak Roentgenographic observation of the mineralized area with diffused state. These results demonstrated that type IV collagen was a favorable augmentation material in clinical usage for carrier of BMP.

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A 24-years-old female patients with skeletal mandibular prognathism was scheduled for orthognathic surgery. Her chief complaint was mandibular deformity, and bilateral saggital split osteotomy under general anesthesia after preoperative orthodontic treatment was planned. However, she had a severe bronchial asthma, and her pediatricians advised that she was the contra-indication for general anesthesia. Thus she underwent body ostectomy under local anesthesia with significant improvement of her occlusion and jaw deformity. No respiratory complications occurred.

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