口蓋の形態変異の成因に関する因子分析学的研究

顎顔面頭蓋形態との関連において

抄録

The purpose of this study is to clarify the morphological variation of the palate, particularly the etiology of high vault formation with reference to the maxillo-facial-cranial pattern and dental arch. The materials for the study are dental cast models from 204 subjects, 103 males, and 101 females, each with individual normal occlusion. Frontal and lateral cephalograms of each subject were also included.
Method: From each dental model, the palatal height (PH 3-PH 4), palatal width, palatal length were measured between 31-13 and 7-7. The palatal volume was measured by moire topography method to calculate the mean palatal height (MPH). In order to simulate the maxillary dental arch with a quadratic function, each point of measurement of 14 teeth was put into coordinates by using a digitizer. The determinant coefficients for ellipse, parabola and hyperbola (R²) were then obtained. Optimum curve was selected by using maximum R values. On the frontal and lateral cephalograms, on the other hand, the maxillo-facial-cranial pattern were analyzed on 59 items by the Down, Northwestern and Coben method.
Results:(1) From the analysis of the relationship between PH 3-PH 7 and values of measurement from the cephalogram, an environmental factor was found to predominate on the anterior part of the palatal height, whereas a hereditary factor was apparently dominant on the posterior part.(2) The maximum R value was obtained for ellipse in 169 subjects (82. 8%), parabola in 35 subjects (17. 2%) and hyperbola in O, indicating the highest adaptability to ellipse.(3) After the palate height was classified, using±S. D. of MPH as the criteria for grouping, the HV group occupied 27 of 204 subjects (13. 2%).(4) The correlation coefficient between MPH and RLS, r=0. 486 and the relationship between the HV group and those with a constricted dental arch was objectively demonstrated.(5) The characteristics of the profile of HV group were shown to consist of high N-Me, and Ans-Me.(6) Based on the result of factor analysis of the maxillo-facial-cranial pattern, 10 factors were found to have a cumulative rate of participation of 96. 2%. Factor I was the mandibular protrusion and rotation factor including RLS, Factor II was identified as the mandibular clockwise rotation factor accompanied by a horizontal jaw and facial growth inhibition factor antagonizing Factor I. Factor III was superior facial height related to the discrepancy between the upper and lower jaw. Factor IV was relative protrusion factor. Factors II, III and IV extraeted the chararteristics of adenoid profile, representing the main cause of mouth-breathing.