当教室ではこれまでに，歯列模型がデータの欠落なく短時間で計測できるシステムを開発してきた．今回は，計測時に座標軸をそろえていない2種類の歯列模型の中から任意の特定部位を重ね合せできるソフトを新たに開発した．

抄録全体を表示

Application of virtual reality haptic device for dentistry is in our present subjects. To simulate the haptic feeling in the dental treatment, it is necessary to detect the tactile-force between objects such as instruments and intraoral organs. So development and application of inter-objects taqctile-force feedback system was investigated. In the present study, the haptic support of bone drilling by the help of surgical template, especially in the patient with small mouth opening was intended. In such case access of the drill from above the template is often impossible. Then, approach from the side inductive groove was attempted, and haptic simulation system to realize this method was assembled.As a result, the present inter-objects tactile force feedback system to feel the contact with drill and groove in the surgical guide was successfully functionated. This method will be exten-sively applicable to train dental tactile treatments.

抄録全体を表示

欧州では，オゾン化オイルは古くから皮膚疾患やカンジタ症などの治療に使用されている。 我が国でもオゾン化オイルによる治療が多く報告されているが，日本の厚生労働省はオゾン化オイルを認可していない。 欧州では既にオゾン化オイルは多くの薬局で販売されていて、日常使用されている。我が国も早期にオゾン化オイルを厚生労働省が認可し、市販されることが切望される。 そこで、本研究の目的は，医療用オゾン化オイルを短時間に製造できる装置を試作し，実用化することである。

抄録全体を表示

今回，我々は各種波長のレーザーの持つ色による吸収特異性に注目し，赤，青，緑，紫色のう蝕検知液で染色したろ紙にレーザーを照射し，ろ紙を透過するレーザーのエネルギーをレーザーエネルギーセンサーで測定し，その吸収率を算出し，レーザー波長の色による吸収特異性を検討する．その結果，半導体レーザーに対して，青もしくは緑のう蝕検知液でう蝕を染色した場合，選択的除去ができる可能性が示唆された．

抄録全体を表示

In this study, we measured the permeability of the 405-nm diode laser light into the dentin for clinical use such as dental hypersensitivity or pulp capping. Forty extracted bovine mandibular anterior teeth were used. Dentin permeability was about 30% at thickness of 0.5mm and 15% at thickness of 1mm and 5% at thickness of 2.0mm.There was a correlation between the permeability and the thickness of the dentin. This result suggested that the 405-nm diode laser may become one of the options of the treatment of dental hypersensitivity or the inflamed pulp.

抄録全体を表示

Introduction: 臨床でEr:YAGレーザーを用いて歯の切削を行うとき，外部から注水しながら行うのが通例である。しかし，水の役割については議論がある。歯の構成成分であるハイドロオキシアパタイト内にもOH基が含まれていることが混乱の一因である。そこで，演者らは乾燥歯と湿潤歯に対して外部環境を変化させレーザー照射し、切削時に歯の内部の水と注水が切削に及ぼす影響を検討した。 Materials and Methods: 実験に用いた試料歯は、抜去歯を電気炉内で125℃、24時間乾燥させた歯（乾燥歯）、抜去後直ちに生理食塩水中で保存した歯（湿潤歯）とした。照射条件は試料歯のエナメル質と象牙質に対して先端チップと試料表面との距離を0.1 mmとして、パルス幅を10 ns、照射エネルギーを200 mJに設定し、3 Hzで1秒間（3パルス）と5 Hzで2秒間（10パルス）の2条件とした。外部環境は，照射時の注水を軽水（通常の蒸留水）、重水および大気の条件で行った。なお、軽水はEr:YAGレーザーから放射された光子を吸収するが，重水は吸収しない。形成された切削痕を走査電子顕微鏡にて撮影し、試料表面における面積と深さを計測した。計測結果を歯の乾燥の有無、外部環境および照射パルスを因子とした３元配置分散分析によって検討した。 Results and Discussion 乾燥の有無について、エナメル質、象牙質ともに切削面積は湿潤歯のほうが乾燥歯よりも大きかった（ p <　0.01）。切削深さは、エナメル質では湿潤歯のほうが乾燥歯よりも大きかった（ p <　0.01）が、象牙質では有意差がなかった。 外部環境について、エナメル質では切削面積は重水、軽水、大気、深さは軽水、重水、大気の順に大きかった。象牙質では切削面積は軽水、大気、重水の順に大きかったが、深さには有意差がなかった。 切削面積は乾燥および外部環境の影響を受け、深さは、エナメル質では乾燥の有無および外部環境の影響を受けるが、象牙質では受けにくいことがわかった。

抄録全体を表示

日亜化学が開発した青紫半導体レーザーの医療への応用の一貫として，青紫半導体レーザーによるチタン表面改質の可能性を調べた．また，TiO2溶液塗布のようないろいろな表面の処置と組み合わせた．光触媒効果の評価として接触角測定およびメチレンブルー分解試験，抗菌性の評価として細菌付着試験，生体適合性の評価として骨芽細胞の付着について調べた．メチレンブルー分解試験においては，TiO2溶液を塗布後にレーザー照射を行った試料において有意に分解が進んでいた．(p<0.05)

抄録全体を表示

ガラス繊維強化樹脂の破壊様相についてアコースティックエミッション（AE）法を応用し計測した．本実験では，ファイバーポストと同じ組成の板状試料を用いた．試験は，熱疲労（0，5000，10000回）を試料に与えた後，AE計測を行いながら，三点曲げ試験を行った．各条件下におけるAEの発生様式が異なり破壊様相の違いが認められた．

抄録全体を表示

Introduction: In clinical use the clasp arms may be chosen within the limits of the real conditions, but a design producing less stress is the most important parameter. The aim of the study was to create digital three-dimensional teeth and cast clasps models in order to design and optimize dental clasp arms. Materials and Methods: Plaster teeth were scanned and the data were processed in order to create continuous surfaces of the teeth and to generate solids. Purposely designed experimental three-dimensional models of the clasp arms were constructed on the teeth surface and imported in a finite element analysis software for structural simulations. Results were displayed as colored stress contour plots to identify regions of different stress concentrations. Discussion: The described methods can generate detailed three-dimensional models of teeth, which can be used to design and optimize dental clasps. Conclusions: The reconstruction method using laser scanning can generate detailed and valid three-dimensional models of teeth, which can readily be used for clasp design applications. Three-dimensional finite element analysis allows the investigation of the preferable design for the cast circumferential clasp arms.

抄録全体を表示

Adsorption behavior of lysozyme that is rich in sariva and known as an antibacterial protein, onto some dental material-related subustrates was studied by QCM method. Au substrate showed a strong affinity for Lyz in any condition studied (pH 3 or 5, C_s = 0 or 50 mM). Oxide substrates (SiO₂, TiO₂) showed a pH dependent adsorption that could also be affected by salt, which indicated an electrostatic attraction between the surfaces and Lys. The current QCM study showed that Lyz was expected to be adsorbed onto gold alloys, porcelains and titanium structures, partly by an electrostatic interaction.

抄録全体を表示

Absorption of impact force of an experimental mouth guard material prepared from PEMA (Polyethylene methacrylate) powder and divinyl sebacic at a P/L ratio of 1.2 g/1 ml had been evaluated by a new impact testing device. Commercial mouth guard materials mainly composed polyvinyl-acetate-polyethylene (EVA) copolymer were also been tested. The experimental mouth guard material showed minimum impact transmission. Among the various thickness, 1 mm EVA copolymer and 2 mm experimental material showed better impact absorption from 50 cm height with a free falling steel ball.

抄録全体を表示

Mean surface roughness, wear values, and maximum worn depths of various resin composites after toothbrushing were compared using powered toothbrush with oscillating-rotating brush head. This method was an acceptable wear test for the evaluation of surface degradation of resin composites.

抄録全体を表示

Introduction: Microplasma welding of dental alloys, in an inert gas environment, have led to substantial improvements to the traditional joining procedures used in denture technology. The purpose of the research was to assess the welding quality of Ni-Cr alloys used in fixed dental prosthodontics, depending on their chemical composition, structure and the selected welding parameters. Materials and Methods: For experimental tests different Ni-Cr alloys were selected. Plates were cast conventionally using an induction melting centrifugal casting machine. They were welded bilaterally in a butt joint configuration, varying the device parameters, using a microplasma Welder. Welded specimens were analyzed macroscopically, microscopically, radiographic, metallographic and the microhardness was determined in the base metal (BM), weld metal (WM) and heat affected zone (HAZ). Results: Even the chemical composition of all the alloys was similar, the weldability was different. Discussion: The areas with microstr uctural changes and increased microhardness values, located in the HAZ are fragile structures, that can lead to an early degradation of the welded structure during functional loads. Conclusion: Ni-Cr alloys with similar composition may react differently to the welding process.

抄録全体を表示

Introduction: The occurrence and progression of a caries lesion are associated with an imbalance or equilibrium of de- and remineralization. The progressing pattern of caries is observed not only in the subsurface lesion but also in surface-softened lesion. The progression of caries in the grooves also might depend on the pH changes inside of the grooves. The aim of this study is to analyze of the demineralization pattern in the different grooves using New software as a convenient analysis method for dental microradiography. Materials and Methods: A 100µm thickness single-section specimen was prepared from human extracted molar. All of surfaces of the specimen, except for the area studied, were coated with Sticky Wax. Two different grooves with 200µm (N group: n=6) or 400µm (W group: n=6) width accompanying 1-mm depth were prepared in the human molar. The coated surface of specimen was covered with Para film and these specimens were immersed into the fluid with automatic-pH-cycling system. The system was carried out at 9 cycles /day during 2 or 4 weeks, in which the pH value was kept for 37 min under 5.5 at one cycle. The Transverse microradiography images (TMR images) were taken before and after the procedure of pH-cycling. The parameters such as mineral loss (∆Z), lesion depth (Ld), surface zone depth (SZd), and lesion body depth (LBd) of tooth specimens and additionally the outer surface zone (OSZ), inner lesion body (ILB), and sandwich area (SA) between OSZ and ILB — which together constituted ∆Z – of the dentin at enamel-dentin junction were calculated by the newly developed program (Fig.1). Results: The subsurface lesions were observed in the group W at any weeks. whereas those were found in the group N only at week 4. ∆Z and SA were significantly higher in the group W than in the group N at any weeks. (Paired t test, p<0.05). Disccusion: These results indicate that not only the demineralization volume but also the demineralization pattern of dentin are depending on the width of grooves artificially made. Conclusion: The caries lesion will start the surface-soften lesion and subsequently progress into the subsurface lesion

抄録全体を表示