With the intention of clarifying the change in the components of F.C. which was being used in dental practice, formaldehyde in it was estimated by colorimetric determination with chromotropic acid. F.C. subjected to the analysis had been used for 2 or 4 weeks by 30 clinicians of dentistry. Results were as follows : 1) It is confirmed that the change of formaldehyde content observed in this experiment fits in well with the results of our former investigation, (1971) concerning the degenerative change of F.C. kept under the modeled condition of dental practice. 2) Degenerative change progresses more rapidly in F.C. kept in a container which is turned upside down every time when used than in one which is kept upright.

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The purpose of this study was to prove the relationship between gingival massage with a toothbrush and increased protection of gingiva. Fifteen clinical students with a healthy gingiva participated in this study. The maxillary left incisors, canines and labial marginal gingiva were decided as the experimental side and the right side as the control. The participants stopped their oral hygiene during the experiment, but an examiner performed gingival massage twice every day. At the gingival massage, the examined teeth were covered with a vinyl chloride plate in order not to remove the plaque. The schedule of this study was as follows : 1. Preliminary period. (20 days, scaling, brushing and flossing once every day) 2. Experiment period. (30 days ; gingiva of the experimental side was stimulated with a toothbrush twice every day) Plaque score was evaluated according to the P.I. (Loe & Silness) every fourth day and gingival condition was evaluated according to G.I. (Loe & Silness) every second day by the examiner. Also gingival exudate was scored on 0, 14th, 22nd and 30th day and gingival pocket depth was scored on 0, 14th and 30th day. During the experiment, there was no significant difference between the P.I. of the experimental and control sides, but gingival inflammation of the experimental side developed more mildly and slowly than that of the control side.

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The present study was designed to investigate the difference in reflex discharges of the hypoglossal nerve by changing the stimulating portion of the tongue. Tactile and chemical stimuli were applied to two or three portions of the tongue surface and a single electric shock was applied to two branches of the glossopharyngeal nerve supplying the tip and root of the tongue. Reflex discharges were recorded from two branches of the hypoglossal nerve supplying the intrinsic and hyoglossal muscle. The main findings were summarized as follows. 1. Tactile stimuli of cotton fibers applied to the tip, root and middle of the tongue surface elicited reflex discharges in two branches of the hypoglossal nerve. Reflex discharges were the largest in frequency and amplitude when the tongue was stimulated on the tip, and the smallest discharges were generated by stimulus applied to the root of the tongue. Reflex discharges in the branch to the intrinsic muscle were greater than that in the branch to the hyoglossal muscle when any portion of the tongue surface was stimulated. 2. Chemical stimulus with 0.3M NaCl elicited reflex discharges, but stimulus with Ringer's solution did not elicit an obvious discharge. Reflex discharges generated by chemical stimulus were large in frequency and amplitude and lasted a long time. Reflex discharges generated by the stimulus with 0.3M NaCl applied to the tip of the tongue were greater than that generated by the stimulus to the root of it. 3. A single electric shock to the branch of the glossopharyngeal nerve elicited reflex discharges in the branches of the hypoglossal nerve. The threshold value of reflex discharges generated in the hypoglossal nerve by a single electric shock to the branch to the tip of the tongue was lower than that when applied to the branch to the root of it. In this case, the threshold value of reflex discharges elicited in the branch of the hypoglossal nerve to the intrinsic muscle by an electric stimulus was lower than that to the hyoglossal muscle. 4. Reflex discharges of two branches of the hypoglossal nerve become greater in frequency and amplitude with an increase in the amplitude of the compound action potential of the glossopharyngeal nerve when stimulus was increased.

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Using the serial gnathostatic models longitudinally taken over a period of about three years from 37 males and 32 females from 6 to 17 years of age, and using a new measuring method established in which the palatal vault was set as the standard point for measuring. The length and width of the maxilla and mandible apical bases and the dental arches, and changes in tooth inclination were examined longitudinally for four groups consisting of normal occlusion, maxillary protrusion, anterior cross bite, and crowding. Changes in maxillo-mandibular horizontal relation were also examined. Results are summarized as follows : 1. The horizontal changes with growth of point 'a', which is the anterior point of the maxillary apical base, was minimal for each group. However, the horizontal changes with growth of point 'b', which is the anterior point of the mandibular apical base, varied. As a result, the horizontal distance between the points 'a' and 'b' increased for the maxillary protrusion and decreased for the anterior cross bite. 2. The difference in the length of the dental arches between the maxilla and mandible was stable for normal occlusion, whereas the difference decreased for the maxillary protrusion and for anterior cross bite, but increased for crowding. 3. The width of the apical bases and of the dental arches increased to the age of 17 but no distinct difference was indicated between normal occlusion and malocclusion for both maxilla and mandible. 4. As to the changes in molar inclination, distal tipping decreased in the maxilla, medial tipping decreased in the mandible, and buccal tipping decreased, for each group. No significant difference was indicated between normal occlusion and malocclusion.

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Observations were made of the changes in the nerve fibers of dental pulp. Investigations were made of the teeth taken from tumor lesion diagnosed as being squamous cell carcinoma. Nerve fibers disappeared gradually, beginning with those near the center of tumor lesion, along with degenerative changes of the dental pulps. Whether such findings were caused by the tumor itself could not be concluded due to the limited materials and to the types of therapy to which the materials had been subjected. The author intends to continue investigations on a various kinds of tumors.

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Two cases of anomaly in the ramification of aortic arch were encountered by the authors during the dissection practice for students in 1977 as follows. 1. No.311 : age 83, female Both the brachiocephlic trunk and left common carotid artery ramificated from the common trunk originating from the aortic arch. This case belongs to Type B by the classifications of Adachi (1929), Umesue (1942), and to Type C by De Garis (1933). 2. No.257 : age 58, male Anomaly was seen in that left vertebral artery which ramificated directly from the aortic arch. This is Type C by the classifications of Adachi and Umesue and Type D by that of De Garis.

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In addition to the normal position for tooth development and eruption, transposition, rotation and impaction of tooth are often found. The normal position for tooth eruption is in the jaw bones, labial and buccal side. We encountered with a rare case with the wisdom tooth developed and erupted aberrantly into the left cheek in the mandibular angle portion. A farmer, aged 25, visited our dental clinic on March 10, 1940, with the chief complaint of ectopic eruption of the left lower third molar into the left lower cheek. Family History : Nothing noteworthy. Patient's History : |V^^- decayed when he was 5 years old. No treatment was given because no dentist resided in his village. Therefore he suffered from Osteomyelitis and sequesterotomy (approximating hemi-mandibulectomy) was performed half a year later. Physical Examination : The patient looked moderately nourished. B.T. : 36.3℃ ; P.R. : 85 times/min. A scar was observed in the left lower cheek, measuring 3cm in length. Because of the sequesterotomy, his face looked peculiar like a bird-face. A tooth with the buccal cusps down and lingual cusps up erupted in the left lower cheek in the mandibular angle area. The 16 permanent teeth of upper jaw erupted completely. No dental caries was found, but severe calculus deposition was observed. In addition, odor oris was noted. No tooth was found in the remaining lower dental arch and it looked atrophic. Treatment Procedure : Under the local anesthesia, the tooth was extracted smoothly with an elevator. The wound was sutured with 2 stiches. The extracted tooth was like wisdom tooth from its appearance and measured 1.7cm in length. The crown was 0.6cm mesiodistally. The mesial and distal roots measured 1.0cm and 1.1cm respectively and were 1.0cm apart from each other. The pulp cavity was proved to be existing by X-ray examination. Conclusion : 1. A man aged 25 had the left lower living wisdom tooth developed and erupted ectopically into the left lower soft tissue in mandibular angle area. 2. The causative factor of this tooth aberration was considered as follows : Under the stress of pathologic change and sequesterotomy, the tooth germ moved into the soft tissue and erupted in the place of the least resistance in the mandibular angle area. 3. From this case, we may conclude that the tooth germ can develop and erupt within the soft tissue.

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