We investigated the relationship between masticatory performance, occlusal force and dentofacial morphology in 50 adults. Masticatory performance and occlusal force were evaluated using color-changeable chewing gum and pressure sensitive occlusal sheets. The measurement indices of lateral cephalograms and plaster models were used to assess dentofacial morphology.
     We found that masticatory performance significantly correlated with occlusal force in both males and females. It also correlated with the angle of convexity, the A-B plane angle and the curve of Spee in females. In males, the occlusal force correlated with SNA, the angle of the mandibular plane with SN, the gonial angle and the OM angle. In females, it correlated with SNA, A'-Pt', the angle of the mandibular plane with SN, the mandibular plane angle with the FH plane, the occlusal plane angle with the FH plane, the width between the maxillary canines, the maxillary dental arch length and the curve of Spee.
    These results suggest that the anteroposterior position of point A and the curve of Spee influence masticatory performance and occlusal force.

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We investigated the capacity of optical diagnosis technology to evaluate oral biofilm. Informed consent was obtained from 11 patients who were seen at the Osaka Dental University Hospital for treatment of periodontal disease. Their teeth were observed using the Penscope^® and red fluorescence plaque detector (Red Plaque). Tooth surfaces covered by Red Plaque were photographed with the Inspector Pro™ and the maximum (ΔR Max) and the average (ΔR Average) red-fluorescence intensity were calculated. The periodontal status of each subject was evaluated using the periodontal index (PI), probing depth (PD), attachment loss (AL) and bleeding on probing (BOP). The Red Plaque samples were analyzed by the polymerase chain reaction method and bacteria associated with periodontal disease were detected. There was no correlation between PI and the percentage of tooth surface covered by the Red Plaque. Nor was there any relationship between the red-fluorescence intensity and the statuss of the periodontium. However, we found that Treponema denticola (T.d) correlated with the intensity of red-fluorescence. It is thought that T.d increases as plaque matures. We concluded that optical diagnosis technology can evaluate the maturity and pathogenicity of oral biofilm.

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Application of water spray is standard when using the Er:YAG laser for the clinical ablation of teeth. It is because the ablating efficiency improves. However, its role is controversial. The reason is that the water molecule is originally included in the hard tissues of teeth. We studied the role of water molecules in the laser-ablation of porous ceramics made of hydroxyapatite (HAP) and fluoroapatite (FAP). The sample specimens were immersed in water to fill the pores before irradiation by the laser. In order to distinguish the effect caused by molecules in the specimens from that caused by water molecules outside, we used light and heavy water during the laser irradiation. This is because light water absorbs the photons emitted by the Er:YAG laser while heavy water does not. We found that the water contained in the specimens played an important role in ablation of the HAP. The rate of ablation caused by the water molecules outside the specimens was no less than that caused by molecules inside for each apatite. When the imprints of the ablation on the HAP and FAP specimens were compared, it was found that the hydroxyl radicals in HAP made a large contribution to the laser-ablation.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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