2005 Fiscal Year Final Research Report Summary
The comprehensive study of the causes of non carious cervical lesions and mandibular tori
| Project/Area Number |
15570198
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Anthropology
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| Research Institution | Nihon University |
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Principal Investigator |
IGARASHI Yuriko Nihon University, Scholl of Dentistry at Matsudo, Lecturer (Full-Time), 松戸歯学部, 講師 (60277473)
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| Co-Investigator(Kenkyū-buntansha) |
MATUSE Miyoko Nihon University, School of Dentistry at Matsudo, Associate Professor, 松戸歯学部, 助教授 (70165265)
SHIMIZU Takehiko Nihon University, School of Dentistry at Matsudo, Lecturer (Full-Time), 松戸歯学部, 講師 (40328761)
KANAZAWA Eisaku Nihon University, School of Dentistry at Matsudo, Professor, 松戸歯学部, 教授 (70050648)
KONDO Shintaro Showa University, Scholl of Dentistry, Lecturer (Full-Time), 歯学部, 講師 (60186848)
YAMASHITA Masaki Dokkyo Medical University, Department of Medicine, Research Assistant (Full-Time), 医学部, 助手 (80255009)
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| Project Period (FY) |
2003 – 2005
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| Keywords | non carious cervical lesions / mandibular tori / present day Japanese / Jomon people / Kamakura people / modern Japanese / environmental causes / biomechanics |
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| Research Abstract |
The frequency and morphology of non carious cervical lesions (NCCL) were examined in Japanese isolated teeth (276 upper incisors, 179 upper canines). Before examinations, we defined a new classification system. NCCL were found in 38% of incisors and in 63% of canines. The shapes of NCCL were classified by the contour of sagittal section and by the contour on surface. In incisors and canines, different types of NCCL were found, and the causes of NCCL have been suggested to be different by the kind of tooth.
The frequency and morphology of mandibular torus, and the correlations between the development of tori (the class of tori and the size of the tori) and environmental factors (the number of teeth, the degree of crowding and the degree of dental attrition) were examined by skeletal materials of Jomon people, Kamakura people and modern Japanese people, plaster casts of present-day Japanese dental patients, present-day Japanese students and present-day Papua New Guinea Highlanders. Before examinations, we defined a new torus grading system. There were no statistically significant differences between males and females and between left sides and right sides in the distribution of torus classes and positions. 83.5% of Jomon people, 62.3% of Kamakura people, 64.8% of modern Japanese, 76.6% of present-day Japanese patients, 72.0% of present-day Japanese students, and 80% of present-day Papua New Guinea Highlanders had palpable tori. In Jomon people, tori were most frequently found under the second and first molars. In other groups, tori were most frequently found under the first and second premolars The development of tori has been suggested to positively correlated to the degree of dental attrition, the number of teeth, and age, and negatively correlated to the degree of crowding. Biomechanical study has suggested that tori develop in the mandible with more high density of compact bone.
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Research Products
(4 results)
