生後5週齢のWistar系雄ラットを対照群, 標準食・活性型ビタミンD_3群, 低亜鉛食・活性型ビタミンD_3群, 高亜鉛食・活性型ビタミンD_3群の4群に分けた.4週間飼育した後, 亜鉛及び活性型ビタミンD_3の成長期歯槽骨の骨成長に与える影響について検索し, 次のような結果を得た.1. 体重 : 対照群と他の3群との間に有意差は認められなかったが, 低亜鉛食・活性型ビタミンD_3群と高亜鉛食・活性型ビタミンD_3群の間には有意差があり, 後者が高値を示した.2. X線骨密度 : 各群の平均値の差の検定を行ったところ, 低亜鉛食・活性型ビタミンD_3群と高亜鉛食・活性型ビタミンD_3群との間に5%の危険率で有意差があり, 後者が高値を示した.3. 病理組織所見 : 対照群に比べ低亜鉛食・活性型ビタミンD_3群において骨層の菲薄化, 低石灰化層の増加, ハバース管周囲の骨小腔の減少と疎な配列, 辺縁の不規則化がみられた.標準食・活性型ビタミンD_3群ではハバース系, 骨小腔などが増加傾向を示しており, 骨層の厚みも増加していた.高亜鉛食・活性型ビタミンD_3群では骨層はさらに増加し, ハバース系, 骨小腔も増加し密に配列し, かつ再石灰化層の増加も著明であった.4. 走査型電子顕微鏡所見 : 低亜鉛食・活性型ビタミンD_3群における骨基質形成面は吸収面が厚く, その再表層部には疎なコラーゲン原線維網が多く認められた.一方, 高亜鉛食・活性型ビタミンD_3群における骨基質形成面は休止面が多く認められ, そこには密なコラーゲン原線維網が表層部を被っていた.標準食・活性型ビタミンD_3群は対照群とほぼ同じ所見を示していた.5. 血液学的所見 : 内分泌機能検査において血中カルシトニンは低亜鉛食・活性型ビタミンD_3群では対照群に比べて, 有意に低値を示していた.このことから骨吸収抑制作用の低下が示唆された.以上のことから, 亜鉛摂取による影響は骨構築に対し, 促進作用があるのは明らかである.正常な骨代謝状態を営んでいる状態の中での低亜鉛, 高亜鉛の作用は生体恒常性を超えるものではなかった.また活性型ビタミンD_3は骨構築の改善には有効であるが, 単独では亜鉛不足を補う強い作用はみられなかった.

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細胞表面抗原のCD4に陽性なヘルパーT細胞(Th)は, サイトカインの産生する種類によってTh1とTh2の2つの亜集団に分類されている.一般的に, Th1は細胞性免疫を誘導し, Th2は液性免疫を誘導する.幼弱なCD4陽性ヘルパーT細胞からこれらの亜集団への分化は, 種々の条件によって影響をうける.その条件のうちの一つは, 抗原の種類であると信じられている.我々は先にLipopolysaccharide (LPS)のラットへの注射は, 大きな抗体産生を誘導し, 一方卵白アルブミン(OVA)の注射は, 小さな抗体産生を誘導することを見いだした.この免疫学的な違いは, それぞれの注入した抗原により, 誘導されたThの性質に依存しているのではないかと考えた.この可能性を確かめるために, OVAまたはLPSをラットの腹腔内に接種し, 脾臓細胞からOVAまたはLPSに応答して特異的に細胞増殖をする, ヘルパーT細胞クローンを樹立した.それぞれ5種類ずつ, 任意に樹立したヘルパーT細胞クローンを選択し, それぞれをOVA特異的またはLPS特異的Thクローンとした.ヘルパーT細胞であることは, W3/13HLK(抗ラットT細胞)とCD4陽性であることから確かめた.選んだOVA特異的Thクローンの5種類全ては, Th1様の性質を示した.すなわちこれらのクローンはインターロイキン2とインタフェロンを産生し, 遅延型過敏症を誘導した.また選んだLPS特異的Thクローンの5種類全ては, Th2様の性質を示した.すなわちB細胞による抗体産生を助けた.従って, 腹腔内免疫よって誘導されるThクローンの亜集団は, 使用した抗原の種類に主に依存していることが示唆された.

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ヒトの幼児期に相当する生後5週令のWistar系雄ラットを用い, 亜鉛が成長発育期の軟骨内骨化による骨形成に及ぼす影響について検索した.本研究では, 成長発育期の骨形成において亜鉛の影響を調べるために亜鉛含有量の異なる食餌を与え, その影響をラットの下顎頭軟骨を用いを用いて検索した.実験には小児期に相当する生後5週齢のWistar系雄ラット(40匹)を用い, 無作為に次の4群に分けた.対照群(標準食) : ラット標準飼料(オリエンタル酵母工業)と水道水にて飼育した.亜鉛欠乏食群 : 亜鉛欠乏飼料(オリエンタル酵母工業)と水道水で飼育した.低亜鉛食群(50%) : 低亜鉛食飼料(オリエンタル酵母工業)と水道水で飼育した.高亜鉛食群(150%) : 高亜鉛食飼料(オリエンタル酵母工業)と水道水で飼育した.骨塩量, Ca, Pの定量分析, 病理組織所見ならびに走査型電顕所見より総合的に判断して, 成長期の下顎頭軟骨は骨形成において亜鉛が必要不可欠な微量元素であり, さらに亜鉛摂取量を増加させることにより骨形成作用を促進されることが示唆された.

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On the anterior teeth arrangement and placement for complete denture constructions, morphological features of the natural dentition are generally used for reference materials as in Payne's statement of "Set the dental teeth where natural teeth grew". In this study, fifty three subjects (male : 11, and female : 42, 18.7±2.9 years old) from five thousand three handred and seventy seven with the individual normal occlusion were selected according to Miyamura's standards, and were examined about the frontal natural dentition and the contour of alveolar ridge. The results obtained are as follows : 1. On the central incisors 1) In the frontal view : Only 5.4% of the subjects possesed the deviation of 0.0mm to 0.1mm between the frenulum of upper lip and the midline of both central incisors, but no subject above 1.1mm in the deviation was recognized. In the deviation between the midline of the maxillary and the mandibular central incisors, no deviation was 7.5%, and most was bellow 1.0mm, and in the midline of the central incisors and the frenulum of the lower lip, no deviation was 21.1% in all subjects. 2) In the horizontal view : The central incisors were located at 8.7±1.3mm anterior to the line bisecting the incisive papilla. 3) In the sagittal view : The inclination of maxillary central incisors to the prosthetic plane was 98.6±6.3°, and that of mandibular ones 93.7±5.2°. 2. On the canines : Coronal plane through the middle of the incisive papilla passed through 0.1±1.9mm posterior to the cusp of canines on the dentulous casts. 3. On the vertical difference of the upper six frontal teeth : As to the vertical positions of the lateral incisal edges and the canine cusps to the central incisal edge, in the lateral incisal edge it was located higher by 0.5±0.5mm than the central incisal edge, and in the canine cusp lower by 0.2±0.8mm. 4. On the occlusal relationships of the central incisors : The vertical overlap of the central incisors was 2.3±1.1mm, and the horizontal overlap 2.9±1.0mm, and high correlation was recognized between their occlusal relationships. 5. On the sagittal alveolar ridge and tooth contour at the mandibular central incisor portion : The horizontal distances from the cervical portions to the central incisal edge, and the most protrusion and the deepest undercut of alveolar ridge were 0.4±0.7mm, 0.0±0.3mm, and -2.2±1.0mm respectively. 6. On labial surfaces of both maxillary central incisors as viewed from the incisal edge : Subjects classified into the soft lateral type, the hard lateral type, and the straight type were about 35.8%, 24.5%, and 39.6% respectively. And among the female subjects, the hard lateral type was recognized in about 29%, a against only in about 9% in the male. On the basis of the foregoing findings, constructive observations were obtained for the complete denture construction with regard to providing patients' SPA factors and making functional denture contours harmonized with the surrounding tissues such as the muscles of orbicularis oris and mentalis, as seen in the labial surfaces of the mandibular anteriors and the alveolar ridge contour on the sagittal plane, and more as evidenced in the labial surfaces and arrangement of the maxillary central incisors on the occusal plane.

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Measurements of the maxillary incisors were taken in four tribes (Han tribe, Man tribe, Hui tribe and Chaoxian tribe) living in Northeastern China. Regressive phenomena of the lateral incisors and comparison among four tribes were investigated. The results were as follows : 1. Both the central and lateral incisors were the largest in the Man tribe and the Hui tribe, but the smallest in the Chaoxian tribe. 2. The incidence rate of microdont in the lateral incisors was the highest in the Han tribe and the Chaoxian tribe, and microdont scarcely appeared in the Man tribe and the Hui tribe. 3. As compared with the central incisors, the reduction index of the lateral incisors showed low diminution rates in the labiolingual diameter among the four tribes. In the mesiodistal diameter, however, the diminution rates were extremely high and the Han tribe and the Chaoxian tribe showed higher reduction rates than the Man tribe and the Hui tribe. In the crown area, the Han tribe showed the highest diminution rate after the Chaoxian tribe. 4. On the basis of the incidence rates for the group with an extensive degree of definite regression of the lateral incisors and for the group with a slight degree of regression, determined by the reduction index, regression in the labiolingual diameter was slight in most cases. Of the four tribes, regression in the mesiodistal diameter was highest in female of the Chaoxian tribe, and was lowest in male of the Man tribe.

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The purpose of this study is to clarify age-related changes of the mandibular bone marrow using MR imaging. This study involved 95 cases (males : 51, females : 44) of MR imaging randomly selected with no hematopoietic or bone disease in the mandible. The youngest subject was a 6-month-old boy and the oldest subject was an 80-year-old male. The cases were categorized as 30 mandibular symphysis regions, 66 mandibular premolar regions, 70 mandibular molar regions, and 63 mandibular ramus center regions. The T1-weighted MR images of bone marrow used in this study were obtained utilizing the spin echo technique. The scanning parameters were TR 500 msec, TE 15 msec, 8 mm section thickness and 10 mm section intervals for adults, 5 mm section thickness and 6 mm section intervals for children. Bone marrow images were sectioned into the sagittal section of the mandibular symphysis, coronal section of the mandibular premolar and molar regions, and horizontal section of the center of the mandibular ramus. MR signal intensity of the bone marrow on T1-weighted MR images were classified into three grades : (a) low, (b) high, and (c) mixed (high and low). The results obtained were as follows : 1. The varied signal intensities of the 30 T1-weighted MR images of the bone marrow in the mandibular symphysis : (a) 16 (53%) showed a low signal intensity. Of these 16, 5 were in the 61-70 age group and 4 were in the 0-10 age group. (b) 11 (37%) showed a high signal intensity. The high signal intensity was observed in other groups except for those in the 11-20 and 21-30 age groups. (c) 3 (10%) showed a mixed signal intensity. These 3 were the lowest among the three grades of signal intensity. 2. The varied signal intensities of 66 T1-weighted MR images of bone marrow in the mandibular premolar region : (a) 16 (24%) showed a low signal intensity. Of the 16 subjects, 8 in the 61-70 age group had the highest number of low signal intensity of all groups. (b) 23 (35%) showed a high signal intensity. Of these 23, 6 in the 41-50 age group and 6 in the 61-70 age group were of the highest number in high signal intensity. (c) 27 (41%) showed a mixed signal intensity. These 27 cases were the most numerous among the three grades of signal intensity. Of the 27, 7 in the group of 61-70 age range, 6 in the 51-60 age range, and 6 in the 71-80 age range were the highest number. 3. The varied signal intensities of 70 T1-weighted MR images of bone marrow in the mandibular molar regions : (a) 16 (23%) showed a low signal intensity. Of the 16, 8 in the 61-70 age group were the most numerous. (b) 23 (33%) showed a high signal intensity. Of the 23, 7 in the group of 61-70 age range and 6 in 41-50 age range were most numerous. (c) 31 (44%) showed a mixed signal intensity. These 31 cases were the most numerous among the three grades of signal intensity. Of these 31, 8 in the 71-80 age group, 7 in the 51-60 age group, and 7 in the 61-70 age group were the most numerous. 4. The varied signal intensities of 63 T1-weighted MR images of the bone marrow in the center region of the mandibular ramus : (a) 11 (17%) showed a low signal intensity. Of the 11, 4 in the 51-60 age group and 4 in 61-70 age group were most numerous. (b) 45 (70%) showed a high signal intensity. These 45 cases of high signal intensity were the most numerous among the three grades of signal intensity. Of these 45, 13 in the 61-70 age group were the most numerous. (c) 7 (11%) showed a mixed signal intensity. These 7 cases of a mixed signal intensity were fewest among the three grades of signal intensity. Mixed signal intensity was seen in all of the age groups except for those in the 11-20 and 31-40 age groups.

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