良好な咬合保持者の顎・顔面形態に関する研究
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概要
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Usually, diagnosis and treatment plans are made on the basis of data obtained from subjects with normal occlusion in orthodontic treatment. Morphologically, there are three types of faces for subjects with normal occlusion : convex, straight, and concave. It is therefore necessary to adjust treatment goals in accordance with the facial type to maintain stable and consistant treatment results. However, taking measures by the facial type has not yet been sufficiently pursued. Therefore, relations between antero-posterior relationships of the upper and lower jaws and tooth position were studied with regard to subjects with good occlusion. Of 1, 047 male students whose gnathostatic models, oriented facial photograms, and roentogenocephalograms were completed and in custody of the Department of Orthodontics, Kyushu Dental College, 178 subjects who had Angle class I relationships and good occlusion, both overjet and overbite, over 0.5mm and under 4.5mm were selected for the study. With use of their lateral roentogenocephalograms, linear and angular measurements were taken on 35 items and examinations including multiple regression analysis were made. The results were as follows : 1. Convexity[mm]of the materials used for this study was -7.0 to 10.0mm (1.7±3.0mm), A-B was -18.3 to 3.5mm (-5.8±4.2mm) and ∠ANB was -5.1 to 8.6°(1.9±2.4°). Within these ranges, maintenance of fairly good overjet and overbite was considered possible even with antero-posterior skeletal discrepancy of the upper and lower jaws. 2. Correlation coefficients of convexity[mm]with A-B and with ∠ANB were -0.82 and 0.96, respectively, showing strong correlation. The greater the convexity[mm]was, the greater the antero-posterior difference of the upper and lower jaws was skeletally. With smaller convexity[mm], antero-posterior difference of the upper and lower jaws was smaller. 3. Correlation coefficients of convexity[mm]with ∠FH-1 and with ∠FH-1 were -0.43 and -0.72, respectively. With greater convexity[mm], the upper central incisor tended to show lingual tipping and the lower central incisor labial tipping. With smaller convexity[mm], the trend for both incisors was reversed. 4. In multiple regression analysis, the linear measurement items N-A, N-B, and A-B with FH plane as the base were expressed by a contribution of 0.96 and over derived by angular measurements of ∠SN-FH, ∠SNA, ∠SNB, and ∠ANB with SN plane as the base. Each of FH plane and SN plane has advantages as the plane for measuring. Therefore, in making evaluation of antero-posterior relationships of the upper and lower jaws, linear measurements with use of FH plane and angular measurements with use of SN plane should be taken into consideration.
- 九州歯科学会の論文
- 1986-10-25