Grant amount：\3250000 （ Direct Cost: \2500000 、 Indirect Cost：\750000 ）

During the grant period, (1) A computer aided system was developed for recording of torque and force exerted during root canal preparation in vitro. In the system, sampled data are displayed as a torque-force curve on a Cartesian coordinate system in real-time.(2) It was revealed that operators were able to change their manipulating torque and force with visual information displayed on the computer monitor. (3) A novel procedure based on regular expressions was developed for extracting a particular manipulation pattern (watch-winding motion) from torque-force records.

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Grant amount：\43350000 （ Direct Cost: \37500000 、 Indirect Cost：\5850000 ）

The efficacy of the experimental dentin bonding system to the cervical defect and the sound dentin cavity was evaluated by measuring the contraction gap width of the resin composite. Twenty extracted human teeth with and without cervical defect and twenty intact extracted human teeth were used. For ten teeth with cervical defect, the defect surface was conditioned with neutralized 0.5 mol/L EDTA (pH 7.4) for 60 sec followed by rinse and dry. Then the cavity was primed with 35 vol % of gtyceryl mono-methacrytate solution for 60 sec followed by air blasting. The resin composite was filled in the cavity after application of the commercial dual-cured dentin bonding agent Ten minutes after the polymerization of the composite, the specimen was sectioned through the canter of the cavity and the maximum contraction gap width was measured on the section of the cavity using the light microscope. For ten specimens with cervical defect, the dentin priming was omitted though other steps were performed in the same methods. The cervical cavity was prepared in the twenty intact human teeth and restored with the resin composite mediated with the experimental dentin bonding system with and without dentin priming. The gap formation was prevented completely in the primed cavity regardless of the kind of the dentin. When the priming was omitted, the complete cavity was observed in the seven specimen of the cervical defect though gap was observed in all of the specimens in the cavity prepared in the intact teeth. Thus it was concluded that the dentin in the cervical defect was more beneficial for dentin bonding than the sound dentin probably because the monomer diffusion and the water through was limited by the debris in the dentin tubules.

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Grant amount：\1800000 （ Direct Cost: \1800000 ）

難治性感染根管治療への高周波通電の有効性を検討するため以下の実験を行った。
<実験1:寒天培地を用いた高周波通電による殺菌効果の検討>
培地1mlあたり約10^6個の菌濃度となるようにE.coli菌液を混和して普通ブイヨン寒天培地を調製した。高周波治療器コスモエンドシステム(コスモトレード社製、東京)にファイルチップを装着し、培地表面から約2mmの深さまでチップを挿入し高周波を通電した。高周波通電の条件として通電時間は0.3秒、0.5秒、1.0秒で各通電時間共、出力3、通電回数3回とした。好気条件下で37℃24時間培養後、菌の発育阻止帯を3次元的に観察した。
<実験2:高周波通電の根尖病巣模型内細菌に対する殺菌性の検討>
透明根管模型(ニッシン社製)を用い根尖病巣の実験モデルを作製した。即ち、根管模型の根尖に根尖病巣の腔を作製後、根管を#90まで拡大した。直径O.9mmの矯正用ワイヤーを根管口より挿入して根尖孔から2mm突き出した状態で固定し、根尖部に形成した腔内に生理食塩水で調製した寒天を流した。羊脱繊血に菌を混ぜ約10^7個/mlの濃度に調製したE.coli菌液1μlを寒天の硬化後ワイヤーを引き抜いてできた穴の中に微量マイクロピペットを用いて根管方向より注入した。根尖孔からファイルチップを2mm突き出し、実験1と同様な条件で高周波通電を行ったのち寒天と一塊として菌液を回収し、分散均-化後、普通ブイヨン寒天培地に接種し、37℃24時間好気条件下で培養後CFUを測定した。
<実験1:結果>チップの周囲約0.5mmの範囲で殺菌されていることが確認されたが実験の各通電時間の間で殺菌範囲の大きさに差は認められなかった。
<実験2:結果>通電を行った全ての試料で、生育細菌数はコントロールの1/10〜1/100に減少し、殺菌効果が認められたが、通電時間の長さでは生育細菌数に差は認められなかった。

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Grant amount：\3500000 （ Direct Cost: \3500000 ）

In conventional procedure of caries treatment, it is demanded that the infected dentin is completely removed. In some case, the pulp was removed, as a result, the life of teeth was became shorter. Recently, minimal intervention dentistry is recommended. In this study, re-carcification of infected dentine was studied. The properties of glass-ionomer restorative cements containing mixed antibacterial drugs were studied. The more amount of mixed drugs contained in cements, the greater inhibition zone on BHI blood agar was observed. However, this also resulted in decreased mechanical and physical propertied of cements. The fluoride release from fluoridated adhesive restorative resin materials and new developed Compomer, fluoride uptake into surrounding tooth structures and the effect of their acid resistance were investigated. Glass-ionoomer cements showed higher fluoride release than those of resin and Compomer. WDX analysis showed the fluoride concentration on dentin and enamel contact area, after 60 days of immersion in deionized water. The acid resistance of enamel and dentin plates which contact with fluoride releasing restorative materials was increased. There is a higher possibility for the presence of caries around margins of restorations, application of fluoridated adhesive materials will lower this possibility and prevent secondary or initial caries around the margins of the restorations in both enamel and dentin. Also, this study showed the infected dentin is re-mineralized using the fluoride releasing materials. It was suggested that a new detection system for caries using the laser apparatus is useful to evaluate the re-mineralization of tooth.

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