A 40-year-old female patient visited the Tohoku University School of Dentistry, Department of Prosthodontics in 1976 requesting restoration of esthetic appearance. The patienthad had open face crowns with a prosthetic space appliance cemented to both right and left uppercentral incisors in about 1962.
Following this treatment, the patient had not been satisfied with the prosthetic space applianceand metallic portion of the open face crowns.
Intraoral examination revealed a spaced dental arch in both the upper and lower jaws, butperiodontal disease was not obserbed by either radiographic or intraoral examination. In general, prosthodontic treatment by itself is not satisfactory for restoration of esthetic appearance and, therefore, orthodontic treatment in combination with prosthodontic treatment is required. In andprior to 1976, the application of MTM (minor tooth movement) in patients older than 40 years of agewas rare.
This is a report of the prognosis 11 years after prosthodontic treatment in combination with MTM to restore esthetic appearance. After 11 years, a space of 0.8mm between the upper centralincisors as well as attrition of the artificial teeth of the partial denture were found, but the prognosiswas good since no breakage of the coronal prosthesis or the partial denture was obserbed.
We therefore report this case together with reconsideration of the original treatment plan.

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In complete denture fabrication, the stress concentration in the supporting structures should be avoid. Such stresses can produced pain during function or ulcerations of the supportingtissue. This study examined the effect of the arrangement of artificial teeth on the stress distributionsin the supporting structures under the denture. The denture with three different arrangementsof artificial teeth were simulated using a two dimensional viscoelastic finite element stress analysis.
The results were as follows:
1. The area of greatest stress concentration was mylohyoid region because the mandibulardenture rotated in that direction. The denture was supported on the lingual slope of the residualridge.
2. As the position of the artificial teeth moved from lingual side to buccal side, the stressintensity at the high stress concentration area decreased and the stress distribution in the soft tisssueand bone became uniform.
3. As compared with the results under the different loading condition, the displacement of thedenture in the lingual direction and the stress intensity at the mylohyoid region increased when theconcentrative vertical load applied at artificial teeth.

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Magnetic resonance imaging (MRI) of the temporomandibular joints (TMJs) were studied in 58 craniomandibular disorder (CMD) patients and 5 normal volunteers, by taking eitherthe gradient echo or spin echo pulse sequence in combination with the single or dual surface coil.Furthermore, 3 subjects from both groups were also studied with arthrography. Results showedboth the MRI and arthrography to have the same findings in regard to the condyle-disk relationshipat both positions of the mouth closing and opening among the 6 subjects.
Although the MRI had previously been thought to provide no evidence of disk adhesion in theupper joint compartment, cine MRI induced by a fast-scan mode enabled us to distinguish those diskswith adhesion from those without. Direction of the disk displacements were judged by combiningthe MRI on the coronal and sagittal planes. The bilateral simultaneous cine MRI was thought tobe of help in evaluating the coordination of the condyle movement associated with each disk.
Utilizing the cine MRI with a dual surface coil seemed to have greater value not only in termsof screening TMJs, but also for evaluating the therapy needed for CMD patients.

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This study was carried out to obtain the exclusive bonding agent for the trial relining material made of cyclophosphazene monomer [4PN-(TF)₂-(EMA)₆]. Namely, adhesive strength was measured on tensile test under various composition formulae and treatment times.
Relining specimens after bonding tereatment, performed to place on a base resin plate (size 15×20×3.5mm), contact with a circle of 3mm diameter. The trial exclusive bonding agent wassingled out obtained good results. And a commercial bonding agent were used for their own.
Adhesive strength were measured and compared between the commercial relining materials and the trial, and the following results were obtained:
1. Base on adhesive strength, a trial exclusive bonding agent was thought to have a good result at the composition mixted of MMA: CH₂Cl₂:HEMA=10:50:40 (as wt%).
2. For the best treatment time, base on adhesive strength, about 60 seconds were thought to be sufficient time until the relining after brushed the trial bonding agent on a plate.
3. The best standing time until visible light curing was 60 seconds.
When the trial relining was performed under conditions described in sections 1, 2 and 3, adhesion strength was greater than that of the commercial material, suggesting that the trial bonding agentis potent of clinical application. The purpose of this study was therefore fulfilled.

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Examinations were carried out on the relationship between craniofacial morphology and the bite force in vertical clenching in 11 males having healthy teeth and mandible who wereclassified in the long face group. Thus, what were differences present in the bite force of the longface as compared with the normal face and short face group, were examined, and the followingconclusions were drawn.
1. No significant correlation was observed between almost all determined parameters anddesignated ranges.
2. The directions of bite force (θ=64.2-66.6°) in the long face group were to the sameextents with the normal face and short face group.
The directions of bite forces in the long face group (θ=52.6-55.0°) were to the same extentswith the normal face group but significantly smaller than the short face group.

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The relationship of the craniofacial morphology with the EMG activity of the masticatory muscle and bite force in vertical clenching was examined in 11 subjects having healthy teethand mandible classified in the long face group, moreover the EMG activities of the masticatorymuscles in the normal face group and short face groups were comparatively examined, and thefollowing conclusions were drawn.
1. Significant correlations were observed in the designated ranges in part of the increasingpart and the holding part, i. e., positive correlations of the temporal muscle with CC⊥UAG-KR (A), CC⊥UF (B), θ', and θ, positive correlations of the masseter with Ar-Go, AG-KR, CC⊥UF (B), and CC⊥U AG-KR (A), negative correlations of the masseter with θ', and θ, and MP-OP, a negativecorrelation of the lateral pterygoid muscle with SN-MP, Ar-Go, and positive correlations of themedical pterygoid muscle with AG-KR, CC⊥UF (B), CC⊥UAG-KR (A), and B/A were observednegative correlations of the medical pterygoid muscle with θ', and θ.
2. The unit of EMG activity of the temporal muscle in the long face group, except for 25% MC, was significantly smaller than that in the normal face group. In all the designated ranges, themasseter and lateral pterygoid muscle showed the same extents with those of the normal face group, but the medical pterygoid muscle showed significantly greater as compared with the normal facegroup. The temporal muscle in the long face group was to the same extent with the short facegroup in 75 and 100% MC, but was significantly smaller in 25 and 50% MC. In all the designatedranges, the masseter was significantly smaller, but the lateral pterygoid muscle was to the sameextent, and the lateral pterygoid muscle was significantly greater than in the short face group.

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As inorganic components of dental hard tissue, calcium phosphates whose compositions resemble each other are applied to various uses, and these compounds are the materials on which the present discussion is focussed. Hydroxyapatite (HAP) and its precursor, α-tricalcium phosphate (α-TCP) in particular, each harden when mixed with water or an organic acid solution. These hardened compounds are capable of protecting the pulp. For this reason, they are commercially available as pulp capping materials and as base materials, and have come to be applied clinically.
Base materials in the prosthetic field must possess excellent adhesiveness and strong mechanical properties as well as the pulp-protective effect and a blocking effect on physicochemical stimulation because they are used for the cavity wall of the vital tooth and for the core.
Noting apatite base materials with excellent bioaffinity, the bond strength of each apatite base material to the natural dentin of the tooth, which is a requirement or any base material, was determined and the mechanical properties are also discussed in 6 types of commercially-available apatite base materials consisting of 3 types of HAP material and 3 types of α-TCP material, on the basis of prosthetic clinical application, in the present study.
The results are summarized as follows:
1. As a result of the adhesiveness test, APAMENT of the HAP group showed the maximum level (33kgf/cm²), and BONETRIX of the α-TCP group showed the minimum level (9kgf/cm²).
2. There was no consistent bond strength tendency according to the type, rather, there was more difference among the products than between the types.
3. As a result of the compression test, VITACEMEN of the α-TCP group showed the maximum level (573kgf/cm²) and BIOMENT of the HAP group showed the minimum level (310kgf/cm²).
4. As a result of the tension test, AP LINER of the HAP group showed the maximum level (63kgf/cm²), and BONETRIX of the α-TCP group showed the minimum level (28kgf/cm²).
5. As a result of the test for Vickers hardness, APATITE LINER TYPE II of the α-TCP group showed the maximum level (31Hv), and AP LINER of the HAP group showed the minimum level (10Hv).
6. In assessing compression strength and Vickers hardness by qtest, the α-TCP cements showed higher values on testing for mechanical properties than those of the other types at a significant difference of 99%. The HAP cements showed a greater tensile strength than the α-TCP cements at a significant difference of 99%.

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We examined the relationship between the tooth guide in lateral and protrusive excursions and the temporomandibular dysfunction in 225 healthy volunteers, who observed thestatus of stomatognathic system.
The following results are obtained:
The pattern observed mostly was the guide by the incisor, cuspid and premolars. The cuspidprotected occlusion was seen in 7.5% of the subjects. There was significant difference in theincidence of symptom of TMJ dysfunction between the subjects with lateral tooth guides and withoutthose guides. The rate of the subjects with the same pattern on both side was 45%, in which theincidence of the symptoms were significantly less than that with different patterns on each side.Furthermore, the subjects with guide by posterior tooth excluding cuspid had tendency to show thesymptoms. No-working side contacts were seen in 25.8% in the subjects and especially in secondmolar. There is significant difference in the incidence of the symptoms between the subjectswithout no-working side contacts and with unilateral or bilateral contacts. Although the toothguide on protrusive excursion had no relation to the incidence of TMJ symptom, 7 subjects with open-bite and reversed occlusion had the symptoms of TMJ dysfunction.

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A hypothetical process of speech productive alteration procedures is presented. The recent pronounciation studies in dental prosthetic literature is reviewed with emphasis on statistical references of the sample means. In this case, the alteration level scores of speech production is demonstrated as habituation to follow the sample variances in inter-word or inter-syllabic variations. A dual-type trend of the state in statistical variences, one time-dependent and one time independent, are assumed to develop respectively in temporal sound feature. Syllabic features of time-dependent parameter is effectively displayed in the capital or pre-syllabic word unit. Auditory feedback controls are possively relevant to the second and the ensuring syllables, and are evaluated in the area where the sound parameters are relatively stable. From the neurophysiological standpoint of the speechchain model theory, natural speech sound series consist practically in the chain model. Though, in earlier period, the plate wearer's sounds cause a breakdown of the interrelation of chain model, the sounds are in time recovered from the disorder. In experiments and observations of human habituation in dental research, the series of speech materials should be in chain model and the research object of a unit should be in the first syllable.

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The purpose of this study was to investigate the relationship between internal derangement of temporomandibular joint and EMG activity of the superior (SLpt) and inferior (ILpt) heads of the lateral pterygoid muscles.
Subjects consisted of 5 normal controls, 4 patients with painless click, and 3 patients with closed lock. Together with condylar and incisal movements, EMG was recorded together with at the SLpt and ILpt, the anterior belly of the digastric muscle (Da), the temporal muscle (Tp), and the masseter muscle (Mm).
EMG activity of the SLpt and ILpt was considerably decreased in order of patients with click and closed lock. These patients also showed disorderd synchronization of EMG activity with condylar movement. It became clear that EMG activity of the SLpt and ILpt decreased in accordance with the deterioration of internal derangement of TMJ. It is suggested that malfunction of the lateral ptergoid muscle could participate the deterioration of internal derangemant of TMJ.

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Assessment of occlusal vertical dimension (OVD) is an essential in the dental treatment. However, physiolosical effects of the change in OVD remains unclear.
The purpose of this study is to assess the effect of the change in OVD on the stomatognathic function by analyzing any chewing movements.
Five subjects without any signs or symptoms of craniomandibular disorders and with normal occlusion (age: 24-28 years, 4 males and 1 female) were selected. Onlay-type appliance was fabricated to raise the OVD by about 2mm. The chewing movements were recorded and analyzed using the Sirognathograph Analyzing System III.
As a result, no change was observed in cycle time of the chewing movements, however as for each duration, some changes was observed.

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Four kinds of clinically used shock absorber for dental implants were selected, those, are Delrin^®, Kurepeet dough^®, Monoplast B^®and Acron^®. Next, these materials were applied to the abutment tooth in four ways; the root type, the crown type with shoulder margin and knife-edge margin and the occlusal type. Then, the shock absorbability of each material under abovementioned conditions were measured through the same measuring system at the first report.
The following results were obtained.
1. In the root type, Monoplast B showed the highest and the most stable shock absorbability of all materials.
2. In the crown type with shoulder margin, convergence angle of abutment tooth had no significance in shock absorbability of any materials.
3. In the crown type with knife-edge margin, convergence angle was significant in Kurepeet dough, especially after repeating load.
4. In the crown type, Delrin under the condition of shoulder margin and 0° of convergence angle showed the highest shock absorbability and was not influenced with the repeating load.
5. In the crown type, margin form had no significance in all materials except Delrin.
6. The occlusal type displayed the highest shock absorbability in all types of usage.
7. In the occlusal type, all the materials except Acron were influenced with repeating load.

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Since the ideal color mathching has not certainly been attained in laminate veneer restoration, it might be partly due to the insufficient knowledge about color of natural and discolored tooth. To overcome the problem, it would be important to examine the color difference between natural and discolored tooth. The left upper anterior teeth color were measured in the mouth by a small area colorimeter and evaluated by CIE L*a*b*color system. The following conclusions were obtained.
1. Discolored anterior tooth was darker and more reddish than natural anterior tooth.
2. Concerning the type of anterior teeth, the respective tendency of L*a*b*was the same between discolored and natural teeth.
3. Concerning each part of the same tooth, the respective tendency of L*and b*was the same between discolored and natural teeth.
4. The color difference (ΔE_ab*) compared between each type of anterior tooth, those of discolored tooth were little greater than those of natural tooth.
5. The color difference (ΔE_ab*) compared between each part of tooth, those of discolored tooth were much greater than those of natural tooth.

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The methods for the examination, diagnosis and treatment of craniomandibular disorders are varied among medical institutions. It is intensely hoped that the standardized methods will be established as soon as possible.
Therefore, a patients database and an expert system for diagnosis have been constructed and continued in cooperation with 13 universities. The universities participating in this project were connected through a computer network.
The expert system was developed by using a commercially available construction tool “EXSYS”. The rules of the system were originally obtained from a dentist specializing in craniomandibular disorders.
The purpose of this study was to apply this expert system to patient cases, and to discuss some problems of the system. The result was that the rates of diagnosis agreement between the expert system and 11 doctors were 60.1% in the 28 patient cases.

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High stress concentration in the supporting structures under the denture can produce pain or ulcerations during function. Soft denture liners are used to improve the comfort of removable denture and to reduce residual resorption by reducing impact force and extending the load -bearing area in the supporting structure. The purpose of this study was to predict the effect of the soft denture liners on the stresses translated to the denture bearing area by using viscoelastic finite element method.
The results were as follows:
1. When the soft denture liner was used, stress reduced at the area of greatest stress concentration.
2. Stress in the supporting bone under the denture did not change regardless of use of soft denture liner and reached a maximum value quickly.
3. When the soft denture liner that has large creep behavior was used, the stress intensity in the bone increased with time.

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The purpose of this study was to investigate the effect of the impression methods on deformation of the contour of flabby tissue induced by impression making, using maxillary simulation model with the flabby tissue made of urethane rubber in the anterior region.
The different impressions were made by three elastometric impression materials (polysurfide, silicone-condensation type, silicone-addition type) and nine kinds of impression trays prepared by combinations of spacer (0, 1.5, 3.0mm in thickness) and escape hole (0, 5, 10 pieces) of 2.5mm in diameter.
The universal testing machine (autograph) was used to make impressions under certain relationships between the trays and the model. The inclination of the model to the horizontal plane, which meant the settling direction of impression, was changed anteroposteriorly (anteriorly 20°, 0°, posteriorly 20°) under the condition set up the tray.
Following results were obtained.
1. The deformations of the contour of flabby tissue and their direction depended on the design of the tray like the spacer and the escape hole, the kind of impression materials and the settling direction of impression.
2. Increase in the amount of the spacer and the number of the escape hole didn't always result in decrease in the deformation of the contour of flabby tissue.

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Vinyl silicone impression material, which gives exact impressions and has very little change in dimension, is regarded as the best rubber impression material. But it has some problems yet, for example its hydrophobicitiy.
We evaluated a new polyether rubber impression material “RIM-1” which is developed to solve the above-mentioned problems. The evaluation was made on the physical properties and the clinical application in 60 cases.
As a result, the new impression material had no wrong effect on oral mucous, and gave excellent impressions because of its hydrophilicity and sharpness of hardening pattern.

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To find a more reliable method of measuring the pressure pain threshold (PPT), this study focused on those determinant factors that directly affected it's results and its range of fluctuation. PPTs were measured in normal male adults by a newly developed pressure pain measuring system which enabled one to regulate the pressure rate. Results showed the PPTs in the anterior and lower points of the masseter region to be significantly (p<0.01) lower than those of the center, upper and posterior points at a distance of 1cm among the 26 subjects. PPT also increased significantly (p<0.05) in relation to an increase in bite force among the 15 subjects.
Although the actual PPTs were diversified within a wide range of 1, 558 to 3, 699 gf in the temporal region, and between 918 and 3, 155 gf in the masseter region, their relative values, which were calculated as left to right ratio, were within the range of 91.7 to 115.0% in the temporal region, and 71.0 to 111.0% in the masseter region during the 4 consecutive days of measurement among the 10 subjects.
These results imply that the relative PPT values, under the conditions of steady pressure rate during the jaw rest position, could be of value for evaluating changes in muscle pain. Furthermore, it is important to ascertain that the point of applied pressure is done correctly.

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Depression is a mental problem in elderly dental patients. The purpose of this study was to investigate the relationship between oral status and depressive symptoms among elderly patients. The authors assessed depressive symptoms among dental patients with Zung's Self Rating Depression Scale (SDS). Subjects were 220 patients (88 men and 132 women, average age 74.5yr) who visited the Gerodontic Clinic of Tokyo Medical and Dental University. The cut-off point for depression in a geriatric population is 48. A factor analysis was done, and four factors were obtained: quality of life (QOL), depressive mood, instability of emotion and sociability.
The results were as follows:
1. The prevalence of depressive symptoms was 5.9%.
2. The SDS and depressive mood scores were significantly higher in women than in men.
3. The SDS and QOL scores were significantly higher in upper edentulous patients than in other patients.
4. The SDS and QOL scores were significantly higher in upper complete denture wearers than in other patients.
The results suggested that residual teeth are important for good life of the elderly.

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In the present study, we examined the conditions of denture construction to prevent the upper complete denture from the ingress of air during mastication.
These conditions were designed by simulating the denture border seal in the region of posterior palatal border and vestivular sulcus (the former: postdam, the later: peripheral seal) and furthermore three different positions of the posterior teeth in buccopalatal direction.
In addition, The loads, which induce during chewing three kinds of foods in the incisor and molar region, were simulated.
The following results were obtained.
1. The postdam and the peripheral border seal were usefull for preventing the upper denture from the ingress of air.
2. Having both the postdam and peripheral seal have more effect on the denture border seal than having either of them.
3. The postdam could work more effectively for the denture border seal than the peripheral seal.
4. Negative pressure generated under the denture base could act as one of retention factors of complete dentere and contribute to increase in stability of complete denture, as long as the border seal keeps.

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