We investigated the measurement system of internal voids in impression material using a digital image analyzer explained in previous paper.
In this paper, we investigated the influence of the difference of impression material and mixing method on internal voids.
Nine impression materials were used to evaluate internal voids. They were mixed and injected into a cylindrical plastic ring. After setting, disk specimens were made by cutting them into a same thickness. Area and the number of internal voids that emerged on the surface of specimen were measured.
Quantitative measurement of fine internal voids was made possible by using the digital image analyzer. Each impression material had a large number of internal voids which were less than 0.025mm². In hand mixing, there were significant differences among impression materials with regard to the area and number of internal voids. Alginate impression material had the maximum value and medium-viscosity polyvinyl silycone elastomer had minimum value. Viscosity of impression material was correlated with the distribution of internal voids. In mechanical mixing, the number of internal voids increased slightly and the area decreased significantly in comparison with hand mixing. Using a syringe caused internal voids even in a void-free impression material. Internal voids were produced by mixing more than by the syringe.

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The present study investigated the effects of muscle stiffness of the masseter muscle (Mm) and anterior portion of the temporal muscle (Ta) in various maxillomandibular relations. The results obtained were as follows:
1. Both Mm and Ta exhibited less difference in the stiffness at the rest condition and maximum voluntary contraction when they fatigued. Additionally Mm has a greater difference in the stiffness than Ta before and after fatigue.
2. No change in stiffness was observed from Mm and Ta at rest condition in various position of mandible.
3. When a maximum voluntary contraction was done in dentulous and edentulous subjects, Mm and Ta stiffness increased slightly together with increase of vertical dimension.
4. When a maximum voluntary contraction was done in edentulous subjects, Mm stiffness decreased markedly together with decrease of vertical dimension.
5. As to horizontal movement of mandible both dentulous and edentulous subjects showed the highest muscle stiffness in habitual closing position at the maximum voluntary contraction.
6. In Mm, the stiffness on ipsilateral side and contralateral side at maximum voluntary contraction showed unclear difference, but showed clearly higher muscle stiffness onthe ipsilateral side than on the contralateral side in Ta.
7. Measurement of the masticatory muscle stiffness suggested enable to examine muscle activity.

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Various causes may be complicated the appearance of signs and symptoms of stomatognatic dysfunction.
In this report, the state of patients with stomatognatic dysfunction of an aged person is discussed by statistical observation.
From the results we obtained,
1. The patients of an aged person were occupied 22% of all patients with stomatognatic dysfunction.
2. The chief complaints and present state of them were similar to all of the patients, but characteristic differences were found in some items.
3. The morphological and locational changes of condyle in glenoid fossa were found characteristically in an aged person.
4. As the cause factor, in an aged person, the change of the physiological changes by aging played majour part with occlusal dysharmony. are suggested.

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The purpose of the present study was to establish a simple and objective method for clinical diagnosis of the tooth supporting structures. The method was based upon the detection of acceleration response of the tooth supporting structures applied the step functional load by the breaking pencil-leads.
The parameters, set on the acceleration response wave, were selected which were in the proportional relation with the clinical mobility.
The mobility changes of the same healthy tooth were examined on day-by-day and within-a-day. In a patient worn CSC telescopic denture, the abutment teeth mobility changes were observed through one hundred sixty seven days.
As the results, T 4, the time of the first period of the acceleration wave, was the most adequate parameter for the clinical diagnosis when the labial-to-lingual load was applied to the tooth.

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Prosthetic treatment procedure of the patient with diffused gingival hyperplasia is reported in this paper.
When we make the prosthetic appliances for these patients, we must take their oral hygienic managements for their future into consideration.
Then it is desirable to keep in contact with oral surgeon, periodontist and dental technician.
The patient in this report was female of 56 year old housewife.
A chief compliant was the pain and the masticatory disturbance on the lower right side of mandible.
She had no family history of this disease and dilantin sodium was not taken internally.
This case was diagnosed as diffused gingival hyperplasia according to pathological examination.
After talking this case over with our clinical team, the treatments were determinated as follows;
1. Extracting 13 teeth.
2. Curratage of infected gingiva and alveolar bone.
3. Plaque control.
4. Endodontic therapy of remained 5 teeth.
5. Making upper and lower complete dentures with OPA attachments.
6. Oral hygienic evaluation with Periotron.
7. Masticatory rhythms analysis with EMG and MKG.

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A thermoplastic impression material Adaptol (J. F. Jelenko & Co.) is used for the impression of denture and has attained good results. But the accuracy of the impression material is not distinct.
The purpose of this study was to investigate the influence of handling temperature on dimensional accuracy of the impression material.
Part 1. Impressions were made with Adaptol and custom trays. Accuracy of the impression material was determined by measurement of impressions kept in water at 5, 10, 15, 20, 25 and 30°C.
Part 2. After pouring the stone, impressions were placed into water for cooling or left in air. The temperature of water were 5, 10, 15 and 20°, and the temperature of air was 25°C. Stone casts were made with each temperature. Accuracy of the impression material was determined by measurement of stone casts made from impressions.
The following results were obtained.
1. Changing the temperature of water for keeping, impressions also changed its size. Using water at 20°C for keeping, the impression material indicated best accuracy.
2. As there was no significant difference between measured values of stone casts, the heat evolved at the setting of the stone indicated no influence on accuracy of the impression material.

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For making the apatite implant easy to use clinically and for having the apatite steadily exhibit its bony-ankylotic characteristic, the 2-piece apatite implant system consisting of the root portion, and the abutment portion was developed. The tissue compatibil ity of the root portion as the result of the first stage of the fundamental study of the 2-piec eapatite implant was already reported. Recently, in order to examine the tissue compatibility of the 2-piece apatite implant system in the mass after the cementation of the abutment portion and th e tissue around the 2-piece apatite implant under a functoinal load, with the 2-piece apatite i mplants placed in the lower jaw of adult dogs, the tissue around the implant was histologically o bserved one month after cementing the abutment portion and three and six months after cementing a superstructure.
Results:
1. The root portion in the jaw bone was in ankylotic bone with bone in almost all the parts, in the mucosa around the abutment portion, the inner epithelium was in close co ntact with the abutment portion and, in deeper layers than the inner epithelium, dense fibrous connective tissue covered the abutment portion, thus indicating a good tissue compatibility of th e 2-piece apatite implant.
2. Th e placement of the 2-piece apatite implant under a functional load caused no pr oblems around the implant, or rather the bone holding the implant indicated such pheno mena as thickening and compaction in order to adapt itself to the function.
3. 1 and 2 above revealed that the 2-piece apatite implant technique has no fundamental problems.

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The purpose of this clinical study was to develop the method for comparing the morphological shape of the neutral zone, recorded by a single functional oral movement.
The neutral zone during function was recorded with impression plaster. The function was such as maximum jaw opening, pronunciation of “i” and “u”: and the movement of the tip of tongue toward posterior and upward. These records were cut in frontal plane and these sections were observed in piles with computer graphics.
Findings were as follows:
1. Maximum jaw opening; The buccal an d sublingual region of neutral zone protruded in shapes.
2. Pronunciation of “i”; The buccal region of neutral zone caved in hardly, and its sublingual region protruded more than that of any other functional movement in this study.
3. Pronunciation of “u”; The neutral zone was almost same shape as that of the ma ximum jaw opening. But this shape caved in at the buccal region of first premolar.
4. The movement of the tip of tongue toward the posterior and upward; The buccal region of neutral zone protruded and the sublingual region caved in more than any othe r neutral zone of functional movement in this study. This tendency was more obvious at the molar region than at the premolar region.
From these results, it was recognized that the method which we developed in this study w as very effective to analyze shape of neutral zones.

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Purposing to find out, out of various kinds of tooth carving techniques, a technique, intelligible, simple and free from accident, to the students of dental technician training schools, the authors have made comparative studies on the design cut method our school adopted (A), Obana's dessin mode method (B) and the direct carving method (C). In the previous report, the authors made the freshmen study by themselves these 3 kinds of techniques, evaluated their respective products from the overall viewpoints and dimensional errors in comparison with the standard models, and reported the results.
In the present studies, the students are beforehand given guidance manual and demonstration regarding the above-mentioned 3 methods, and their products are evaluated in the same way as of the previous report. The results are as follows:
1. The evaluation points show a tendency to increase in accordance with the increase in the carving frequency.
2. The average evaluation points of products carved by A, B and C methods are respectively 3.30, 3.16 and 3.26.
3. The increase of evaluation points, compared with those of the self-study case, are 1.21 in A, 1.12 in B and 0.82 in C, that is, guidance manual and demonstration show a remarkable effect in A and B, compared with in the C case.
4. The absolute values of dimensional errors of products carved by A, B and C methods are respectively 8.59, 8.95 and 8.50% in average. Again, in all the 3 cases, the absolutevalues of the dimensional errors decrease by 37.3-40.8%, compared with the dimensional errors in the self-study case, 100%.
5. The range of dimensional errors shows a tendency to decrease, compared with in the self-study case, especially remarkable in A and B techniques.
6. The convergence degree of dimensional errors of products to the standard dimension ± 10% shows a tendency to increase, compared with in the self-study case.

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Muscle fatigue due to clenching, grinding is suggested to be in relation to the pain in TMJ dysfunction patients. A number of investigators report that in normal pe rsons experimental muscle fatigue provoked the similar symptoms seen in TMJ dysfunction patients. These reports suggest that muscle fatigue plays a great role in the onset of TMJ dysf unction.
The purpose of this study was to investigate the effects of muscle fatigue on the silent period of normal subjects. The results were summarized as follows:
1. The silent period during tooth tapping was either absent or incomplete after muscle fatigue. This tendency is seen in patients with TMJ dysfunction.
2. In one subject, double silent periods occurred. After muscle fatigue, the subject may be to have a lower pain threshold.
3. The silent period following jaw-jerk showed significantly shorter latency and longer duration after muscle fatigue. The longer duration may be observed that double silent merged together.
4. In the present study, the silent period is suggested to be useful in the diagnosis and prognosis of TMJ dysfunction.

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In order to investigate the effects of the expansion anisotropy of high-temperature investing materials on the morphology of the inside of cast crowns, cast crowns of nickel-chromealloy (Hi-chrome soft*) were prepared using two types of high-temperature investing materials (plaster and phostphate) and three methods of ring buffering (lined ring, unlined ring, ringless). Morphological changes inside the crowns were then determined with a three-dimensional measuring system. The effects of the colloidal silic solution used for the phosphate investing material on the precision of dimensions inside the crown were also determined. The following results were obtained.
1. When plaster or phosphate was used with or without a lined ring, the overall dimensions of the inside of the crown were larger than those of the prototype. With plaster the internal form was linear, but with phosphate it tended to taper off toward the cervical area.
2. When plaster or phosphate was used with an unlined ring, the internal dimensions of the crown were decreased in the cervical area and increased in height, compared with the prototype. The crown showed a tapering internal form with both plaster and phosphate.
3. The internal dimensions of the cervical area of the crown was increased by 43μm when the ring was buffered (lined with ceramic fiber sheet).
4. When the concentration of the colloidal silica solution was increased from 10% to 30%, the expansion of the internal cervical radius of the cast crown increased from-51μm to 33μm. However, this value decreased to 20μm when the concentration was 40%.

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On the model, in the five cases of missing central incisors or lateral incisors, I picked some teeth in various combinations as abutment teeth, analyzed movement of the loaded bridges, compared each capacity to load and got the following conclusion:
1. The load-capacity index that was in proportion to the capacity of bridges to load was gotten.
2. The relation between load-capacity index and suitability of bridges was examined from the three-dimensional movement of bridges and got the following criteria:
1) load-capacity inde≥20: suitable for bridge
2) load-capacity index 13∼19: border area
suitable for the bridge that abutment teeth at the both sides of missing teeth have balancedresistance
not suitable for the bridge that abutment teeth at the both sides of missing teeth have unbalanced resistance
3) load-capacity index≤12: not suitable for bridge
3. Considering the load-capacity index and the three-dimensional movement of bridges, suitable designs of bridges are following:(1) |1 (2), (3)(2) 1|1 (2)(3), (1) |12 (3), (3)(2) 1|12 (3)(4), (3) 1|12 (3)(4)

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Over 200 prosthesis using adhesive resin have been set for three years from 1982 to 1985 in our clinic.
The patients were recalled and investigated the prognosis of them.
The following results were obtained:
1. Adhesion bridges accounted for more than 80% among them and number of posterior bridges has been increased in every year.
2. Adhesion splints have been mainly used for periodontal splints and permanent fixation after orthodontic treatment.
3. The successful rate of posterior bridges was better than that of anterior bridges.
4. The successful rate of adhesion splints was not so better than adhesion bridges.

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We had the opportunity of treating a patient sufferring from mandibular dysfunction who had no success upon the treatment of pharmacological and splint therapy. However, after treating her with EMG-biofeedback and psychosomatic therapy to relax the hyper tensive masseter muscle and stress, a remarkable recovery was observed along with a 4 year period of normal function.

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With regard to the different kinds of impression methods used in the process of making a full denture, various effects are considered to be given on the forms of surfaces of jaw membrane according to the differences in the impression pressure, because of the fact that the jaw membrane, whose impression is to be taken, has pressure displacement nature.
Then, the impression pressure was checked of each impression obtained by the five technicians, and the vertical displacement amount thus obtaind of the master cast was measured at each of the different measuring sections and a study was thereby made of the effects given to the master cast by different impression pressures. As a result, the following findings were made:
1. The impression pressure is unique to each experiment subject and consequently there are a considerable amount of variations from one subject to another.
2. The amount of impression pressure affects the stopper section on the master cast, praticularly the stopper section in the postdam.
3. At the portion prossessing a bent or a stopper, the effects of the impression pressure is smaller than on the stopper section.

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1. Loading a sequential repetitive click sound signal with a constant frequency of 1.3 Hz, 10 healthy subjects were made to perform jaw tapping movement.
They were instructed to adjust their movement so as to be obtained a coincidentaneous tooth contact with the signal, and after cessation of signal, which was unable to anticipate for subject, to cease their movement as soon as possible.
2. After cessation of the signal, all subjects made one surplus tapping movement without the signal.
3. Regarding DPSP of Mm, IPS of Da and TCPS, no significant difference was found between the last tapping with signal and the surplus tapping without signal (P>0.25).
4. DOSP of Mm, IOS of Da and TCOS in the surplus tapping were to be longer significantly than the corresponding value in the tapping with the last signal (P<0.001).
5. It could be interpreted that these change of tapping movement should be done by “an instant performance control”and this control should be essential to perform thetask in the shortest time with minimum energy consumption.

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When the colors of the maxillary anterior teeth of 23 middle and 20 old-aged people were measured by spectroradiometer, with the aim of harmonizing the colors of the natural teeth in the manufacture of objects of prosthesis and when the results were compared and examined with the measurements of the same using the young people, the following conclusion was obtained.
1. Concerning the difference in different age groups, steady difference with the increase in age was recognized as conspicuously large among the middle aged and the young people-i.e. L* became lower and Cab* became higher.
2. Concerning the difference in colors in different teeth, the tendency of both L* and Cab* was the same among the young people and the middle-aged, while the tendency of Hab°among the middle-aged was the same as that among the aged except among a part of the middle-aged.
3. Concerning the color difference in the parts of the same tooth, on the other hand, the tendency was the same among all age groups-i.e. L* was the highest at the middle part, Cab* was the highest at the cervical and Hab°was the lowest at the cervical.

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The author attempted to examine the influence of occlusion on the regularity of masticatory movement and the muscle activity. Eight Japanese dentate subjects, allin their 20 s, with semi-group functioned occlusion (SGO) were selected and their masticatory activities were recorded simultaneously with a multipurpose monitoring/recording device and the Saphon Visi-Trainer, Model CII.
The masticatory phase, number of masticatory strokes, and duration of muscular discharge were studied by having the subjects masticate peanuts, ham and pickled radish at fixed intervals. The SGO type subjects tended to show different characteristics from those with mutually protected occlusion. In SGO subjects the masticatory path was biased to the grinding style and the ratio of grinding function was dominant. These facts suggest that it is imperativeto take the prosthodontic treatment, diagnosis of mandibular function, occlusal adjustment andreconstruct of occlusion into consideration to determine the type of occlusion of the patients.

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From the standpoint of diagnosing the condition of the gingiva as well as esthetics, gingival color is found to play an important role in dentistry. Thus, it is important to be able to differentiate the changes in color of the portion of gingiva which is in contact with the crown. We the authors of this report, decided to measure the gingival color and make basic investigations pertaining to the conditions in relation to color measurements. The results revealed the following.
It was possible to accurately measure the marginal and papillary gingiva using the modified version of the CD-270 colorimeter, which is considered to be one of the most accurate source of equipement in differentiating color shade.
The detectable color differentiation limit among the dentist of our department was found to be 1.12.
The fixation apparatus for the colorimeter was found to show stable and repeatable data.
It was possible to be able to control the color difference below the afore mentioned detectable color differentiation limit value by a constant color setting established by our department.

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In this study, the author attempted to explicate the infuluence of thedifference in the impression methods for the simulation models based on the hypothetical pressure-displaceability and the form of the alveolar ridge on the reproducibility of the measuring models.
For this purpose, the reproducibility of the master cast were examined by use of the threedimensional position-reproducing apparatus, concerning the two factors the seating speed and the holding pressure of the tray.
As a result of this study, the following conclusion was obtained.
It has been made clear that the impression of dentulous alveolar ridge (the seating speed and holding pressure of the tray) influences the reproducibility of the simulation model. In the impression of the alveolar ridge possessing normal pressure-displaseability, the reproduceability of the measuring cast was the highest when the measurement was made with the tray atthe seating speed of 100 mm/min, and at the holding pressure of 2.0 kgf. Furthermore, it was suggested that when the tray is pressure-adjusted to the alveolar ridge at a standard or slower seating speed, the tray should be held with great pressure, and when the tray is pressure-adjusted speedily, the tray should be held with little pressure.

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Five reference points were marked on the face of 12 adult subjects in midsagittal plane. The speech sample contained 25/s/and 25/m/sounds along with vowels and/sakuranohanagasakimashita/.
Three phenomena were simultaneously recorded by tow high speed TV cameras on same video tapes. These were (1) the motion of facial reference points or the mandibular movements on a MKG, (2) the spectrogram of the voice analyzed by a SSD (Speech Spectrographic Display), (3) the voice of subjects. The record was playbacked on a monitor of high speed TV. The flames, at which consonants were pronounced, were identified by the spectrogram on the SSD. The positions of reference points were computed by the analyzer (Sportias 300).
The results showed that the jaw and the facial reference points moved to different direction, and took specific positions during pronunciation of/s, sh, k, m, h/. In general, the displacement pattern of the jaw was similar to that of the chin. But, in/s, sh/, the movement of the chin was greater than that of the jaw, and in /m/, the chin moved in the opposite direction of the jaw.

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Culture method was used to survey the microflora in supragingival marginal plaque formed on the full cast crown fabricated with platinum gold cast alloy. A band of plaque approximately two millimeters coronal to marginal gingiva in buccal surface was collected from tooth (control group) and full cast crown (experimental group) fabricated with platinum gold cast alloy in mandibular first molar in each subject.
The resuls indicated that there was no difference in the bacterial composition, but that there was a difference in the bacterial proportion between two groups. Experimental group had a significantly higher level of Streptococcus and a lower level of Actinomyces and Veillonella in the microbial proportion than control group. But experimental group had not significantly higher level of Streptococcus in the viable counts per wet weight of plaque than control group. This study suggested that physico-chemical properties had the influence upon the microbial ecology in the process of the plaque formation.

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Recently there are many patients who complain of pain in the TMJs and inthe head and neck muscles as well as of jaw movement disturbances. Some of these patients exhibit the occlusal interferences in the molar region on the balancing side of the dentitions. The causative mechanism of the occurrence of the occlusal interferences on the balancing side were surveyed in the 26 cases of TMJ patients with the occlusal interferences on the balancing sideof the dentitions, who were treated effectively by the occlusal adjustment.
The occlusal interferences on the balancing side have been shown only in the molarregion, particularly in the farthest rearward teeth in the dentitions.
The occlusal interferences on the balancing side were caused by the following factors:
1. The defect of continuity and the difference in level on the occlusal plane caused by the tooth malalignment.
2. The steepness of the curve of the occlusion.
3. The tooth malalignment was caused by the missing, the extrusion, and the tilting of the adjacent teeth, and by the malalignment of canines and premolars.

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