本論文で紹介した顎関節症の診断と治療のためのアルゴリズムは, 歯科臨床家が顎関節症を治療する上で, 患者の立場に立ったクリティカルな臨床的決断 (critical clinical decision) ができるよう考えられている.顎関節症, なかでも最も臨床の場で出くわすことが多い3つの病態, すなわち, 最も頻度の高い顎関節内障の2病態 (円板下顎頭運動制限disc-condyle locking, ならびに円板下顎頭非協調disk-condyle incoordination) と咀嚼筋や顎関節の局所的な疼痛 (筋痛myalgia, 関節痛arthralgia, 変形性関節炎osteoarthritis) が本論文で論じられる内容である.頻度は低いが重要なその他の病態に関しては追って投稿される論文を参照して頂きたい.また, 顎関節症の病因が個々の症例において常に明らかであるとは限らないため, 本論文では, 症状をもとに病態を分類する方法を採用した.したがって, 本論文で選択された治療法は, 原因除去療法とはいえず対症療法とならざるをえなかったが, 現時点で効果がある程度立証されているもので, 生体侵襲性の低いものが選ばれた.本診断アルゴリズムは, 注意深く検者間で評価方法が統一された臨床診査と患者に直接記入させるアンケートをベースに顎関節症患者を各細病態に論理的に分類するもので, 従来の直感に基づく分類とは全く一線を画する.
5つの診断カテゴリーに細病態分類するための基礎データーは, UCLAのTMD治療部に来院した250人の連続サンプルである.このデーターによって明らかに細病態に判別できるかどうかを統計学的に解析するため, これらのデーターは診断樹解析 (discriminate dicision tree analysis) に供され, その結果, 5つの細病態に分類することができた.この際用いられた必須臨床診査ならびにアンケート項目は, たったの3つ (垂直過蓋咬合量を加えた受動最大開口量, VAS (visual analog scale pain) スコアー, 顎関節におけるクリッキングの有無) であった.
これらによって分類可能であった細病態は, 以下の5つ, すなわち, 1) 円板下顎頭運動制限 (disc-condylelocking), 2) 円板下顎頭運動非協調 (disc-condyle incoordination), 3) アルスロマイアルジア (arthromyalgia), 4) アルスロマイアルジアと円板下顎頭運動非協調を併発したもの (arthromyalgia plus disc-condyle incoordination), 5) 顎関節症でないもの (non-TM disorder) であった.これらの分類に加えて, 複数の細病態分類が追加されており, 結果として最終的な診断樹が確立された.
本アルゴリズムは, 徴候や症状の片側のみを重視するものではなく, その両者を併用, 重視しており高い理論的整合性を持つ.また, このような診断方法は, 医科で扱われている筋骨格系疾患におけるスタンダードでもある.また, 5つの細病態分類をさらに分類する分岐点は, 統計分析を行うために必要な患者数が得られないためUCLAの実際のデーターに基づいていない.今後, より多くの患者の連続サンプルが集まれば, これらの分岐点を科学的に明らかにすることが可能であろう.現時点では, これらの追加アルゴリズム分岐点は, 著者の直感的な推測, 他の研究者の文献的研究業績および20年にわたって蓄積された著者のUCLA Orofacial Pain and TM Disorders Clinicでの臨床経験に裏付けられている.本論文で述べられた診断ならびに治療選択法は, 患者にとって最も安全で, 論理的, かつ最も予知性に富む治療介入を可能にしている.

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There are many kinds of stress in dental treatment such as pain or discomfort of denture. Since it is too difficult to judge the stress objectively, it was attempted to judge them with the Clinical Electrocephalograph (SYNAFIT 2100). Using palatal plates, some changes in the EEG rate and the EEG distribution were observed. These results suggested application of the EEG to indicate the mental stress due to dental treatment.

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As described before, we developed a fixed partial denture supported by several pins attached to the proximal surfaces of the abutment teeth adjacent to the missing site. In this study, further investigation was carried out concerning 1) the effects of the pretreatment of adherent surfacesof Ti alloy pin, Ti-Ni shape memory alloy pin, and prepared retention hole on the tensile and shearing forces; 2) the effect of the morphological variance of the retentive region of the pin on the tensile and shearing forces; 3) the effect of the luting cement difference on the tensile force. The pin (1.8 mm length) with a doughnut-like structure was luted to the retention hole prepared in extracted teeth with an adhesive resin cement (Panavia 21, Kuraray) and a glassionomer cement (HY-BOND Glassionomer Cement, Shofu) for various adherent surface treatments.
Overall data showed that the combination of the Ti-Ni shape memory alloy pin and the adhesive resin cement improved the retentive force of the pin.

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The objectives of this study was to investigate the biomechanical causes of hydroxyapatite (HA) coated blade implant fracture. The fractured surface of a broken implant was observed by SEM, which indicated that the fatigue crack started at the distal portion and developed to mesial portion. The fatigue test of the HA coated blade implant showed about 25 kgf/mm2 of fatigue strength. The results of threedimensional Finite Element Analysis (3D-FEA) indicated that the fracture of clinical case No.5 was suspected to be due to the repeated vertical load on the tooth.

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This study was conducted to investigate the bond strength of repair resin to heat-cured denture base resin or pour-type one. The repair surface of test specimens were treated with dichloromethane, methyl methacrylate and alumina air abrasive before self-curing resin was applied to the joint. A shear bond strength test and a three-point loading test were used to determine the shear bond strength and the transverse strength of the respective test specimens. Visual inspection was conducted to determine whether the failure mode was adhesive or cohesive.
The results were as follows:
1. Treating the surface of the denture base resin with dichloromethane and alumina air abrasive were effective to both heat-cured base resin and pour-type one.
2. Effects of both dichloromethane and alumina air abrasive treatments on pour-type base resin were superior than those on heat-cured one.
3. The variations of crosshead speed affected the values of shear bond strengths. This may be related to the failure modes of the specimens and physical properties of denture base resins.
4. A three-point loading test may be appropriate to determine the bond strength between base resin and repair resin.

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In this study, a new analyzing system for occlusal contacts using silicone materials, which applied general-purpose color image scanner, was developed, and the accuracy of this system was analyzed. This occlusal analyzing system made reading the bite registration simple. The results of the measurements concerning the relationship of transmitted light level and silicone materials according to different thicknesses showed that using this scanner could distinguish thicknesses of silicone material that were 40um or less. Image analyzing time took approximately 30 sec after the scanning of a sample. The results of the measurements between the relationship of transmitted light levels at different heights from the measuring surface and silicone thickness showed that distances less than 1.3 mm from the measured region could not be distinguished. However, it was noted that these conditions rarely exist in clinical practice. Based on the results, is was concluded that this analyzing system could be used in general clinical practice.

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Non-coping method for overdenture abutment teeth has several advantages such as avoiding mechanical irritation to the marginal gingiva, allowing patients to make a smooth transition to the overdenture, and facilitating the detection of caries of abutment teeth in their early stages. Tannin-fluoride (HY) preparation was used for caries prevention of overdenture abutment teeth. Caries activity test may be useful to detect patients who are at risk of overdenture abutment caries.
In this study, caries activity of the non-coping abutment teeth was measured for periods varying from 1 to 12 years.
When the caries activity was 0 and +1, there were no abutment caries. When the caries activity was +2 and +3, percentages of caries of HY treatment group and nontreatment group were 5.7% and 44.4%respectively from 5 to 12 years (p > 0.05), and 10.9% and 33.3% respectively in total (p > 0.05).
These results suggested that there is a correlation between these caries activity test scores and non-coping abutment caries, and HY preparation has cariostatic effects even in high caries activity.

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The marginal fit of dental restorations is one of the most important factors influencing the prognosis. For evaluation of the marginal fit, the actual states of fit of the margin to the finish line should be classified and named systemically and reasonably.
The purposes of this study were to select the criteria of marginal fit, to present a system of nomenclature of the types of marginal fit, and to evaluate a scanning laser microscope system for observation and measurement of the marginal fit.
It was attempted to select four criteria for evaluation:(1) Ideal (Id), (2) Open-Closed (Op-C1), (3) Extra-Lined-Intra (Ex-Li-In), and (4) Overlapped (Ov) and the eight types of fit are named as (1) Id, (2) Op-Ex, (3) Op-Li, (4) Op-In, (5) Op-Ex-Ov, (6) Cl-Ex, (7) Cl-In, and (8) CI-Ex-Ov.
The system of scanning laser microscope (Lasertec Co. Japan) was a very suitable apparatus for observing and measuring the marginal fit because of no material limitation and no special treatment of specimen, as well as easy measurement and digital display system for values.

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The purpose of this study was to investigate the influence of the difference in shape of ridge height to the denture mobility and the stress distribution of denture supporting area. A three-dimensional finite element model of ordinary mandibular residual ridge was constructed symmetrical with respect to median sagittal plane (model a) and transformed into 4 other models. The denture mobility and the stress distribution were calculated by a computer under 9 loading conditions.
The results were as follows:
1. High stress concentration was found around the alveolar crest on part of the high ridge area while on the absorption area the concentration was found along the denture border.
2. The denture moved along alveolar crest on the high ridge area, but the denture moved across the alveolar crest on the low ridge area.
3. The denture mobility and the stress distribution of denture supporting area were significantly altered by the difference in shape of ridge.
4. The maximum of stress on the denture supporting area and vector as denture mobility were least when loading forces were localized near the center of the denture model for any model.

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To ascertain the relationship between the incisal and condyle movementsin conjunction with articular disc displacement, mandibular movements and MRI findings were evaluated in 73 TMD patients.
Mandibular movements were recorded during open-close jaw-movement with a six degrees of freedom jaw tracking device, and sagittal MRIs were taken at 15 mandibular positions during open-close procedure.
The results were as follows:
1. Among 73 subjects, 24 were found to have anterior disc displacement bilaterally, 26 having displaced disc unilaterally, including 16 with reduction and 10 without reduction. Twenty-three subjects showed no disc displacement in MRI.
2. Although 9 out of 10 subjects having anterior disc displacement without reduction unilaterally had mandibular rotation toward the side of disc displacement in frontal and horizontal planes, 7 of them moved their incisor points to the affected side.
3. Subjects having a jaw opening range over 45 mm showed smooth mandibular movement regardless of disc displacement, whereas those of the opening range under 40 mm were affected by disc displacement.
The results in this study confirmed that the jaw opening range was one of the intrinsic factors for evaluating TMD patients in the functional aspect. The findings may be useful as important information for diagnosis and management of TMD patients.

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The purpose of this study was to clarify the influence of lateral change of occlusal position on masticatory muscle function. Six healthy subjects with normal dentitions participated in this study. Occlusal position was dislocated laterally at 0, 0.5, and 1.0 mm from the path of habitual closure with maxillary stabilization splints. Then, subjects were asked to carry out habitual closure with an intraoral central bearing device, and mandibular positions at the end of it were recorded. The results showed that mandibular positions deviated from the path of habitual closure and the area of their distribution increased with the change of occlusal position. The direction of deviation differed among subjects and was divided into three patterns.
Next, the factors related to the influence of change of occlusal position were investigated in a series of experiments. The results revealed that periodontal sensation related to the direction of deviation, and psychosomatic factor, in addition to occlusal factor, related to the area of distribution. From a clinical viewpoint, influence of lateral change of occlusal position on the sence of occlusion was examined with the same splints. The results suggested that the subjects were prone to be insensible to dislocation within 0.5 mm.

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Custom-made mouth protectors were inserted into the mouth of seven baseball players, and the effects on respiratory function while playing baseball were studied. Actually, exhalation gas was gathered and analyzed using a gradual load increase method.
The results were as follows:
1. Heart rate was not influenced at all, even though mouth protectors were inserted.
2. Ventilation with mouth protectors was less than without them, but with no significant differences except at 140 and 160 m/min treadmill speed.
3. Vo₂between 140 and 220 m/min of treadmill speed with mouth protectors and V0₂per weight were significantly larger than without them.
4. Ventilation per Vo₂between 140 and 220 m/min of treadmill speed with mouth protectors was significantly lower than without them.
5. Oxygen pulses without mouth protectors increased remarkably between 200 and 220 m/min, while with mouth protectors they increased earlier, between 160 and 180 m/min.
6. No large differences were found in Vco₂, between with and without mouth protectors.
7. Mouth protector can be used in the mouth without athletic impairment.

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Artificial tooth fracture or detachment from the denture base has remained an unresolved problem. However, structural designs in part of anteriors can minimize tooth fracture and detachment.
In this study, designing four kinds of framework (double structure, facing modified double structure, metal backing, and skeleton with the pivot) and no framework as control, the resistance to debonding and fracture of artificial anteriors were measured.
Conventional heat-curing resin as the denture base and crosslinked plastic teeth were used for each specimen. Statical loading test, artificial anterior load applied to the incisal edge and lingual tubercle, was used in the evaluation.
The results were as follows:
1. When the load was applied to the lingual tubercle, the ultimate strength was approximately 2-4 times higher than that to the incisal edge.
2. When the load was applied to the incisal edge, the ultimate strengths of the double structure and skeleton with the pivot were approximately 1.4 times stronger than that of the other designs.
3. Loading to the lingual tubercle, the ultimate strengths of the double structure and facing modified double structure showed the highest, while the control showed the lowest.
4. The failure pattern of metal backing, the double structure and facing modified double structure had cohesive failure within the denture resin.

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The chemical structures and dynamic viscoelastic properties of the proprietary mouth-formed and custom-made mouthguards used in contact sports were investigated to evaluate shock absorption and moldability.
The infrared spectra of the molecular structure of each material were identified as ethylene-vinyl acetate copolymer (EVA). The contents of vinyl acetate in EVA were 27-39 mass%. The weight average molecular weights measured by the gel permeation chromatography were 99, 000-150, 000.
The master curves of storage modulus G′, dynamic viscosity η′ and loss tangent tanδat the reference temperature of 35°C were constructed from the data obtained at different temperatures, by the application of time-temperature superposition principle. By this method, it is possible to evaluate the viscoelastic properties expanded to both higher and lower frequencies than can be obtained experimentally.
The difference of G′ and tanδfor each material was due to the vinyl acetate content and molecular weight in EVA. Marked effects of the molecular weight on the master curves of tanδwere observed in a lowfrequency range: the lower the molecular weight, the higher the tanδ.It was suggested that the shock absorption and moldability of mouthguards could be evaluated from the master curve of tanδ.

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The purpose of this study was to compare the contribution of the inclination of the occlusal plane to the masticatory closing path to that of tooth guidance. Masticatory movements were measured on 38 normal adults using 3-dimensional Mandibular Movement Analyzing System. The direction of the masticatory closing path was calculated at each closing level. The tooth guidance was evaluated as the sagittal inclination of the incisal path during laterotrusion. The inclination of the occlusal plane was evaluated as the sagittally-viewed inclination of the line between the incisal edge and the distobuccal cusp on 2nd molar in the lower jaw. The masticatory closing path outside the intercuspal range was influenced by only the inclination of the occlusal plane. The closing path right before entering the intercuspal position was influenced by the tooth guidance. The inclination of the occlusal plane had great and durable effects on masticatory closing path as compared to tooth guidance.

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A novel system for measuring nocturnal mandibular movements using a PIN photodiode sensor was devised in combination with EMG. The sensing portion of the sensor is divided into four parts, and two axis positions of LED faced to the sensing surface can be detected.
When the LED was moved on the X-Y stage with a micrometer gauge, linearity was kept in the relationship between the output voltage and amount of the movement. The maximum error in the central area of the sensor was about 91 micrometers and that in the peripheral area was about 241 micrometers. Metal splints fitting with the labial surfaces of upper and lower incisors were fabricated to fix the LED and the sensor respectively, and mandibular movements of the frontal view can be measured two-dimensionally in the area around the intercuspal position.
This system was found to be quite useful for measuring not only positions of the mandible but also movement patterns like grinding: these patterns could not be detected accurately by conventional systems.

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A direct retainer's arm is placed on an abutment tooth when an edentulous space is restored by the prosthetic treatment with a removable partial denture. Few analyses, however, have been reported about the effects of retainers on the abutment teeth when the denture base rotates toward and away from an edentulous ridge. A lower second premolar tooth was focused on, and the effects of an extracoronal direct retainer's arm to the periodontal ligament of the abutment tooth were analyzed utilizing the three-dimensional finite element techniques.
The results were as follows:
1. In case the retentive force is located on one side of a tooth and the reciprocal force on the other side,
1) the smallest von Mises stress (relative stress) on periodontal membrane was observed when the reciprocal force appears on the survey line rather than on the proximal surface, on the proximal-buccal corner and on the proximal-lingual corner,
2) and when the value of the reciprocal force is one-third of the retentive force, reciprocal force works appropriately.
2. The proper retentive force is suggested to be lower than 205 g, considering the yield stress of periodontal membrane.
3. It is desirable to make the guiding plane which limits the take-off direction of the denture by producing the reciprocal force on the neck of the retainer's arms when they are located on both sides of atooth.

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The use of the dental adhesive resin cement Panavia 21 (Kuraray, Japan), which showed strong adhesion to a dentin surface pretreated with H3PO4 and NaClO, was previously reported. This dentin bonding system is considered to be effective not only for restoration but also for rebuilding an abutment tooth. The purpose of this study was to evaluate the microleakage in three different core systems using this dentin bonding system. The three core systems were:(1) cast core, (2) resin core with a manufactured post, and (3) resin core without a post. Stress loading and thermal cycling were performed on the specimens, and microleakage was evaluated by the dye penetration test.
The results were as follows:
1. A resin core without a post showed a higher dye penetration rate than a resin core with a manufactured post.
2. There was no significant difference between a resin core with a manufactured post and cast core under stress loading and thermal cycling.
3. A resin core with a manufactured post using this dentin bonding system was evaluated to be as effective as a cast core.

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Pulsing electromagnetic fields (PEMFs) were applied to the oral implants. Fifteen adult male Japanese white rabbits were used. Implants were inserted into the bilateral femurs. As for magnetic intensities, stimulation was applied at 0.2 mT, 0.3 mT, and 0.8 mT with a pulse width of 25μsec, a pulse frequency of 100 Hz, and a duration of stimulation of 8 hours (hrs) per day. With regard to durations of stimulation per day, stimulation was applied under the condition of most effective magnetic intensity. Durations of stimulation per day were evaluated every 4 and 8 hrs. The rabbits were sacrificed at 2 weeks after implantation. Formation of new bone in the groups with 0.2 mT and 0.3 mT were promoted significantly compared to the control group, but the group with 0.8 mT had less increase than that of groups with 0.2 mT and 0.3 mT.
Formation of new bone of each group with stimulation at 4 and 8 hrs was more significant than that in the control group, and that in the group with 8 hrs tended to be more promoted than that in the group with 4 hrs. The above findings show the usefulness of PEMFs in oral implantology.

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Although IPS Empress system has the heat treatment followed by the heat-press procedure, the influences of such processes have not been clearly known in terms of the color changes. Optical characteristics before and after heat-press procedure with and without heat treatment were investigated in both layering and staining techniques. Spectrophotometric measurement was performed by a noncontact type dental spectrophotometer (CAS-ID 1) for analysis of the scattering coefficients, absorption coefficients, R-infinity, color depth, and CIELAB color coordinates. The chemical element component was also investigated with the help of an electron probe X-ray microanalysis (EPMA). All samples were adjusted 0.8 mm in thickness with smooth basal surface.
Little optical characteristical difference was found in staining technique. In the ingots for layering technique, the scattering coefficients increased after heat-press procedure, whereas no changes were found after heat treatment followed by heat-press procedure. The color difference before and after heat-press procedure was caused by increase of L* with decrease both of a* and b*. From the results of EPMA, it was suggested that Sn and Zn were the important factors to modify the color changes after heat-press procedure.

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To elucidate the relationship between masticatory performance and the size of denture foundations in complete denture wearers, 28 complete denture wearers (average age: 75.6±4.8 yrs) whose dentures were developed by one dentist using the same methods and materials were selected. The size of lower denture foundations in each patient were analyzed by the “replica method” newly developed by our department. Replica of each denture foundation was made by silicone impression material filling in the mucosal surface of the lower complete denture and cutting by rubbing the denture border.
The basal area (flat plane cut and rubbed denture border) of residual ridge replica were measured by the digitizer, and volume (weight of replica/specific gravity of silicone impression material) and height (volume/basal area×2) were calculated.
Voluntary maximal clenching force, masticatory efficiency, and cross-sectional area of masseter muscle in complete denture wearers were measured by occlusal force meter (Nihon Koden, Co.), sieving method, and CT-scan.
The results were as follows:
1. The height of residual ridge decreased significantly in relation to aging (p<0.05). But the basal area and volume of residual ridge did not depend on aging.
2. When voluntary maximal clenching force and basal area as well as volume and height of residual ridge replica were dependent variables, and masticatory performance was an independent variable, multiple correlation coefficient (R) as a means of multiple regression analysis was 0.834 (p<0.001).
Partial correlation coefficients (β) of each dependent variable were 0.640 (voluntary maximal clenching force:p<0.01), 0.531 (basal area of residual ridge:p<0.01), 0.489 (height of residual ridge: p<0.05), 0.321 (volume of residual ridge:p<0.05), and they were significant statistically.
3. Voluntary maximal clenching force decreased significantly in relation to aging. The cross-sectional area of masseter muscles by CT-scan did not decrease significantly in relation to aging.

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The purpose of this study was to establish a method for setting a practical personal goal among aged people to maintain oral health with quality of life (QOL), depending on one's oral status. This pilot study was designed to analyze the influence of occlusal support on masticatory efficiency and occlusal forces. Masticatory efficiency tests, occlusal force distribution measurements, oral examination (tooth condition with location, occlusal support area, etc.) along with questionnaires on general health and dietary life (including the number of foods they could eat from the list of 20 items) were conducted in three facilities for 323 Osaka residents. Results indicated that occlusal support has significant influence on masticatory functions such as masticatory efficiency and occlusal forces.

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