In prosthetic treatment of the anterior teeth, esthetic restoration or providing artificial dentition of natural appearance is an important but difficult matter. For the edentulous patients in particular, no clear standards have been established. In selection and arrangement of the artificial anterior teeth, the facial condition, the size and dentition of the natural teeth are of very useful references. The author, therefore, took measurements of the width of the six upper anterior teeth, using the plaster models, and the width of each facial part of adults (male : 116, female : 30) with individual normal occlusion. The results were as follows : 1. The ratio of each size of the six upper anterior teeth was 1__- : 2__- : 3__-=18 : 15 : 17, approximating the ratios arrived at by the other Japanese researchers. 2. The ratios of the width of frontal view of the six upper anterior teeth, when 1__- is 100, were 1__- : 2__- : 3__-=100 : 74 : 64 for the male and 1__- : 2__- : 3__-=100 : 74 : 66 for the female. The ratio was 1__- : 2__- : 3__-=8 : 6 : 5 when the Haga's values were taken into consideration. Compared with those of the other researchers, the width of frontal view of the lateral incisor was larger than that of the foreigners. 3. The width of the central incisor was about 1/16 of the bizygomatic width, about 1/4 of the internal bi-ocular width, about 1/5 of the inter-ala width, 3/5 of the interlabial tubercle width at rest, and 1/2 of the inter-labial tubercle width when smiling. For the male, excluding the relation to the bizygomatic width, a highly significant correlation was recognized. The total width of the six anterior teeth was 5/4 times of the inter-ala width for the male and 4/3 times for the female. 4. In measuring the frontal view of the six upper anterior teeth, the cusp tip of canine was found to coincide approximately with a point slightly inside the outer edge of ala of the nose for the male and with the outer edge of the ala for the female. The internal bi-ocular width was about twice (2.04 times for the male and 2.10 times for the female) as large as the frontal view width of upper central incisors. 5. The internal bi-ocular width, inter-ala width, and inter-labial tubercle width were found to be comparatively effective as the standards for selection of the size and positioning of artificial teeth.

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ラットの葉状乳頭を腐蝕破壊した後の再生過程を, 尿素-硝酸銀法を用いた神経染色法も含めて, 組織学的に研究した.乳頭の再形成は, 神経線維が再生した所にのみ観察され, 再生過程において, 神経線維と乳頭との間に密接な関係がある事が推測された.乳頭の再生初期には 乳頭内には非常に多くの神経線維が観察されたが その数は乳頭の再生が完了するにつれて漸次減少し, 遂には正常葉状乳頭においてみられるのと似た神経線維の分布を示すようになった.味蕾の再生は, 術後35日目以後のすべての実験例に観察する事ができた.再生神経線維が上皮細胞に接触すると, 上皮細胞は味蕾細胞へと形態的変化をする.味蕾は, 再生乳頭の側面と遊離面の両方の上皮内にみられたが, 側面上皮内の味蕾の数の方が多く観察された.このような味蕾の分布様式は, 初期より術後365日目まで変わらなかった.

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Changes in the mandibular condyles during the growth period are greatly affected by growth restraint of the mandible due to orthodontic therapy and by displacement of the mandible. Furthermore, advances in the therapeutic methods made the average age of orthodontic patients higher and widened the age range of the patients subject to therapy. A grasp of aging changes of the mandibular condyle therefore has become an important subject in considering the effects of aging on the temporomandibular joint. The author therefore made an observation of localization of cells, centering around the bone and cartilage, of human mandibular condyles, from the new-born to the aged. For the study, non-decalcified specimens of the least damage to the tissue and suitable for a detailed investigation of the tissue were used. Comparison with microradiogram was made for each specimen. The results were as follows : 1. The articular disk up to the teens contained many young fibers and a large number of fibroblasts was observed. In the ages twenties and older, the collagen fibers were found to be arranged closely and the number of the fibroblasts decreased significantly. No increase due to aging in the chondroid cells was observed and tendency for the chondroid to decrease was observed after forty years of age. 2. The collagen fibers in the articular zone became large and close with aging. The fibroblasts decreased and were rather few in the prime of life and thereafter. The chondroid cells were observed scattered near the surface layer, from about three years of age, and did not vary much in number thereafter but decreased in the aged. 3. The proliferative zone was composed of the chondroblasts. The cells decreased with aging and became flat. The chondroblasts ceased to be observed in some locations in the ages twenties and almost disappeared after forty years of age. 4. The hypertrophic zone became rather thin with aging and the collagen fibers were arranged closely. Accompanying this, the cartilage cells decreased and became smaller. These changes appeared markedly in the ages twenties. The cells became rather few after forty years of age and lost the characteristics and disappeared along with the proliferative zone. 5. Halisteresis occurred, in the prime of life, beginning in the surface, in the layer of mineralized fibrocartilage and the layer became rather thin. 6. The subarticular bone was formed completely in the ages twenties but halisteresis occurred shortly, beginning in the surface layer, and osteolysis increased with aging. 7. The bony cortices of the new-born did not show continuity and a significant bone remodeling was observed in the teens. The bony cortices became thickest between late twenties and thirty years of age and became rather thin thereafter. Halisteresis spreaded diffusely in the surface layer of the bony cortices in the ages twenties. 8. The bony trabeculae, in infancy, were thin and short, distributed closely and arranged about parallel with the length of the mandibular condyle. The bony trabeculae grew thicker and longer till the prime of life but became rather thin thereafter and the number decreased. 9. Arteriolosclerosis (elastic intimal thickening or media thickening) was observed in the arteries distributed in the temporomandibular joint in the ages twenties. These changes showed a tendency to be intensified with aging. Based on the foregoings, it is desirable to commence therapy as early as possible and to complete therapy including retention before the patient reaches the age of twenty.

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The extracted upper second deciduous molars, numbering 269, were classified into six types, type 1 to 6, according to the form of the occlusal surface. Relationships of each type with the tooth crown character and with the measurement value were examined. The results were as follows : 1. The frequency of the Type 3 (a rhombus) was the highest with 55.4%, followed by the Type 2 (a parallelogram) with 15.2%. These two types were the fundamental forms and the other types, the Types 1, 4, 5, and 6, were variations. 2. The tooth which doesn't present the differentiation of the distolingual cusp appeared most frequently in such special types as the Type 1 (a trapezoid) or the Type 6 (a triangle). 3. No relation was considered to exist between the occlusal surface form and the development degree of the oblique ridge. 4. Appearance of the Carabelli tubercle was most frequent in the Type 3. 5. In the relationship between the tooth size and the occlusal surface form, the Types 2 and 3 teeth, which are the fundamental forms, were smaller and the other types showed larger values. 6. Accordingly, it is considered that a deviation of the occlusal surface form in the deciduous molar bears no relation to degeneration phenomenon in the permanent tooth.

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Macroscopic, roentogenological and statistical examinations of 106 cases (151 teeth) with the retained deciduous late in life, from 14 to 47 in age, were conducted. At the same time, histological examinations were made of a portion of the retained deciduous teeth by making section preparations after extractions. Furthermore, a statistical analysis was made of the materials on a total of 899 cases with 1, 756 teeth : 793 cases with 1, 605 teeth of the retained deciduous teeth in the Japanese collected to date since 1919 by the Department plus those by the author. The relations between missing of the permanent successors related to the retained deciduous teeth and resorption of the deciduous teeth root, and the relations to the terminal reduction of tooth were discussed. The results were as followes : I. On the 106 cases (151 teeth) 1. Frequency of appearance by the kind of tooth : As reported by the others, the second deciduous molars (hereinafter called E) showed the highest frequency (52%), followed by the deciduous cainine (24%, called C) and the deciduous central incisor (11%, called A). Both the deciduous lateral incisor (called B) and the first deciduous molar (called D) showed about the same with less than 10%. By the jaw, A and E had a tendency to appear more in the mandible, and B and C in the maxilla. 2. Case distribution by age : The late teens and the first half of the twenties showed the highest frequency and accounted for 70%. There were 3 cases in the forties. 3. Cases by the number of teeth : The cases of one-tooth were the highest with 67 cases (63%), two-teeth cases 34 (32%). Of the latter, 33 cases were of horizontally symmetrical cases. Of these, the most frequent was E (mandible) followed by A (mandible) and C (maxilla). 4. The retained deciduous teeth on the whole were implanted solidly. The incisal edge or the occlusal surface showed rather extensive attrition. Among the deciduous molars, amalgam fillings, inlays, onlays and metal crowns mounted were observed. 5. In the roentogenograms, the dental germs of the permanent successors under all the deciduous teeth were missing. Resorpted roots were comparatively few. 6. Observation of the section preparations revealed minute resorpted lacunae, not distinguishable in the roentogenograms, scattered on the whole surface of the root. II. On the materials on a total of 899 cases (1756 teeth) 1. Frequency of appearance by the kind of tooth : E showed the highest frequency with 48.5%, followed by C (24.2%), D (9.8%), A and B (8.8%). By the jaw, the orders were E, C, B, D and A in the maxilla, and E, A, C, D and B in the mandible. By the sex, B was predominant in the maxilla for the female. 2. Case distribution by the age : The highest frequency was in the range from the late teens to the first half of the twenties, accounting for 64%. There were 24 cases (2.9%) in the range from the forties to as high as 75 years of age. 3. Cases by the number of teeth : The cases of one-tooth case were the highest with 537 cases (64%). Two-teeth cases were 181 cases (22%). Of the latter, 140 cases were symmetrical either horizontally or vertically. By the teeth, E was the highest, followed by C and A. The cases with seven-teeth to all the deciduous (20 teeth) numbered 24. 4. Of the 1, 186 teeth subjected to roentogenological examinations, there were 1, 058 teeth (89%) with the permanent successors missing and 88 teeth (7%) with the permanent successor coexisting.

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From the viewpoint of dental prosthodontic purpose, it is important to restore function and esthetics. Harmony in color is one of the important factors in dental esthetic requirement. Dental porcelain have been widely used as a restorative material because of its ability to maintain its surface texture and color for an extended period without losing its naturalness and esthetic qualities in matching the adjacenting tooth structure in translucence, color and intensity. In the past, however, it was rather difficult to effect porcelain restoration which harmonized in color with the adjacent natural teeth. There are many factors which affect color stability during porcelain firing. With a realization that the number of firing affects color, an experiment was conducted to determine the relations of the number of firing and of the materials to color. For the experiment, vacuum fired porcelain test pieces, containing either opaque, body, or enamel, were subjected to repeated firing in vacuum for a different number of times and to natural glazing after firing. The color and color difference were then determined with a color meter. The integrating sphere system of JIS Z8722-II was used for measuring the color and color was represented by Y.X.Z. of tristimulus values of CIE system. A computer program with the numerical value of Hunter's and CIE color systems was prepared to obtain Hunter's numerical representation (L.a.b) of color. Representation of color and color difference were calculated with L.a.b. numerical values for every test piece in each group, which had been subjected to repeated firings and natural glazing. From the value of Hunter's and Munsell's color systems, the color and its variations were described with popularly used 'Hue, Chroma, and Value'. The ⊿E of color difference in repeated firings and glazing was compared with that of the first firng for each test piece. The results were as follows : 1. The ⊿E of color difference in repeated firings of the opaque test pieces was almost below 1.5 NBS, which varied from 'trace' to 'slight' macroscopically. The changes were caused by an increase in chroma or in value. 2. The ⊿E of color difference in repated firings of the body test pieces was between 0.5 and 1.5 NBS. The change in the range of 'slight' were observed from the 3rd to 6th firings. The changes ranged from 'noticeable' to 'much' after the 7th to 10th firings (After the 2nd to 6th firings in the enamel test pieces). 3. Over 1.5 NBS were detected macroscopically following the 7th or 8th firing of the body test pieces (After the 4th to 7th firings in the enamel test pieces). 4. The degree of color difference increased in proportion to the number of firing in both the body and the enamel test pieces. The changes were caused in most cases by an increase in value and particularly by an increase in chroma. 5. Better surface glossiness was seen following the 1st to 3rd firings but the glossiness decreased thereafter in proportion to the number of firing. 6. Glossiness was lost in natural glazing following the 8th firing in the body test pieces (After the 5th to 7th firings in the enamel test pieces). 7. The test pieces with glossiness after glazing decreased in value.

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