In the cases of dental orthodontic treatment, in which the jaw must be moved, relapses after treatment become problematical. Recently the question of adaptability of the maxillo-facial muscles has been increasing in importance. Considering that relocating the insertion part of the muscle by surgical operation, as is done as part of an operation, when the muscles do not readily adapt themselves to a newly created oral environment, might achieve a similar state where the muscles adapted themselves, the author undertook the experiment. Twenty-two mature male dogs weighing about 10kg each, which were thought to have ceased growing, were used for the experiment. The insertion part of the masseter muscle on each side together with the periosteum was detached from the mandible. These animals were classified into the following 9 groups : 1) Non Bite-raising Group (30th day, 90th day, 180th day) : 2) Bite-raising Group (30th day, 90th day) : 3) Bite-raising Group, for which the bite-raising plate was used for 3 months and then removed, (30th day, 90th day, 180th day) : 4) Control Group. The subjects in each group were killed at the end of the experiment periods and examined histologically and diametrically. The following conclusions were obtained as the result : 1) When bite-raising was done, vertical dimension was increased and regressive changes were observed in the masseter and temporal muscles. The detached muscle was connected with the mandible by connecting tissue at a position slightly above the former location in one month. On the surface of the mandible at this location, bone apposition was formed. The state of healing of the ablation part was slightly delayed compared with that of the Non Bite-raising Group. 2) When the bite-raising plate was removed after conducting bite-raising, extend of relapses was greater in proportion to the increase in vertical dimention. Increase in vertical dimention in the end, compared with that prior to the experiment, was greater although it was of a slight degree. With regard to the masseter muscle, complete normalization could not be seen even after 6 months. 3) The fact that changes in the masseter muscle is slight, compared with those of bite-raising without performing ablation, appears to be indicate that bite-raising combined with periost-ablation at the insertion part has potentiality of restraining relapses after bite-raising in the cases which have ceased to grow. Because the factors that affect relapses also include the jaw closing muscles and others, it is necessary to expedite researches on these factors in the future.

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The metabolism of heavy metal has been investigated by atomic absorption spectrophotometry but the quantity of mercury and cadmium, which are frequent causes of pollution, in human teeth has not been determined well. For this research, therefore, measurements were taken of mercury and cadmium levels through precise basic researches. Mercury was measured by non-flame circulation vapor caused by reagent and cadmium by acetylene-air combustion. The teeth, obtained randomly from three different geographic areas, were defined as dry weight and were ashed by perchloric acid. Then the mercury and cadmium contents were determined. 1. The average mercury level in normal fifty seven teeth was 0.055μg/g. The normal teeth had no significant differeneces among sex, age, type of teeth and geographic regions. 2. Eight normal deciduous teeth had 0.057μg/g of mercury level and fourty nine permanent teeth had 0.055μg/g. There were no significant differences between the two groups. 3. The carious teeth were divided into C_2 (6 cases), C_3 (34) and C_4 (66) and the averages of mercury concentration were 0.081μg/g, 0.069μg/g and 0.075μg/g respectively. The four degree of caries group contained significantly heigher level than the normal teeth. The mercury levels in carious teeth require further examination. 4. The amalgam filling and endodontically treated teeth which were excluded from statistical dealing indicated more than 0.4μg/g of mercury level. 5. The cadmium concentration in twenty five of normal teeth was 0.52μg/g on the average. 6. The mercury and cadmium levels in enamel tissue were apparently higher than those of dentine. The fundamental study made it possible to determine the concentration of mercury and cadmium burden in teeth and to obtain statistical data attributable to region, sex, year, carious degree and tissue from the standpoint of enviromental health. The findings on mercury in this study, in particular, presented base levels expected to be found in general population.

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This study undertaken to investigate the effect on the speech of fistula which had remained after palatoplasty. Thirtythree subjects were classified according to (1) the location of palatal fistula, (2) the dimension of palatal fistula, (3) its dimensional proportion to hard palate and (4) its plane and solid shapes. Examinations were also made on the relation among these 4 classifications and on the changes in nasality following the closure of palatal fistula. Then, 17 subjects were examined on respiratory nasal leakage by manometer, articulation, intelligibility and tendency of abnormal sounds were analyzed and investigated by soundspectrograph. The results were as follows ; 1. The dimension of fistula was the major factor over the effects on the speech. 2. Examinations based on the degree of the effects on the speech confirmed that the factor gave clear differences to the effects. The fistula which is less than 15mm^2 in the dimension, and/or 2% in the dimensional proportion to hard palate, is thought to cause no changes on the speech. The fistula which is 15mm^2 to 30mm^2 in the dimension, and/or 2 to 5% in the dimensional proportion to hard palate, is thought to cause moderate changes on the speech. The fistula which is more than 30mm^2 in the dimension and/or more than 5% in the dimensional proportion to hard palate, is thought to cause remarkable changes on the speech. 3. The difference of the effect on the speech by the locational classification of the palatal fistula, was not observed clearly. The alveolar fistula affected less than palatal fistula. 4. The funnel-shaped fistula which contracted toward nasal cavity affected the speech less than the tube-shaped fistula. 5. The characteristics obtained in analysis of abnormal hearing tendency were the substitution of h-sounds for p-sounds and nasalization of many sounds. It was inferred that such tendency was caused as the result of respiratory nasal leakage the through fistula and a decrease in inner oral pressure during phonation. 6. Analysis by soundspectrograph contributed to the visualization of the results in hearing.

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The patient, a man aged 47, sustained the injury of his upper jaw and lost the <5〓1>___- teeth in a traffic accident three years ago. A year after the accident, the maxillary sinusitis occurred and persisted despite the conservative treatment by an otorhinolaryngologist for two years. Recently, the patient was reffered to our department with a suspicion of a foreign body lying adjacent to the affected antrum. X-ray revealed the presence of tooth-like opaque adjoining the internal wall of the left antrum, so we operated to remove it under the local anesthesia on 20th May, 1974. The tooth-like body was found to be the left upper incisor that was inferred to have been inlayed in the accident. The tooth projected into the antrum, but the radical sinuotomy was not carried out for absence of remarkable inflammation on the antrum membrane. The post medication was indicated for a week, and any sign of sinusitis clearly disappeared. This case points out that a thorough examination at first could have prevented the patient from unnecessary sufferings and that one should never take things for granted in treatment, even of an apparent routine case.

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