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In the malocclusion with mandibular lateral displacement (MLD), it is difficult to establish the functional occlusion by orthodontic means. The careful diagnosis brings us to recognize that MLD condition is the rule rather than the exception. In order to examine the characteristics of the cranio-facial morphology in the cases with MLD, the posteroanterior cephalograms were analyzed. Furthermore, the incidence of temporomandibular joint (TMJ) disorders (joint sound and joint pain) were examined clinically. The results were as follows: 1) Occlusal plane and mandibular plane (the plane running through the anti-gonialnotch bilaterally) inclined superiorly toward the mandibular displaced side. 2) The position of mandibular head shifted to the opposite direction of the mandibular displaced side. 3) The symptoms of TMJ disorders were found in 65.0% of patients with MLD, and more frequently at the TMJ of mandibular displaced side. Considering the evidences, the symptoms of TMJ disorders were much detected and occlusal deviation was found in MLD, it is suggested that mandibular dysfunctions derived from occlusal problems relate to the appearance of MLD. Since both the mandibular plane and the occlusal plane revealed the similar changes in response to mandibular deviation, it is considered that the condition of MLD as skeletal problem may be induced by the functional lateral shift of mandibular position come from occlusal interference during growth period. The deviation of mandibular head may relate to the appearance of TMJ disorders in MLD. Therefore, it is important to recognize the adequate mandibular position prior to occlusal reconstruction, and the vertical dimension control of the occlusal plane is necessary for improving the condition of TMJ and establishing the functional occlusion in the cases with MLD.

It is known that some of the deciduous reversed bite cases are corrected spontaneously by themselves. No decisive conclusion, however, has been achieved so far as to what morphological characteristics the self corrected cases have. The purpose of this study, therefore, was to determine whether the difference between the self corrected group (n) and the non-self corrected group (r) exists at their initial examination or if it occurs as a result of changes in occlusion. The materials used in this study were the serial plaster casts of 29 Japanese girls with the deciduous reversed bite at their first visit and these were measured with the three dimensional measurement system. The following results were obtained: 1. Characteristics of the initial examination with the n group: Overjet (-) and overbite in the n group were smaller than in the r group. The arch length and the perimeter of the maxillary dentition in the n group were longer, and the area of the incisive bone (U-C) was wider than in the r group. Moreover, the upper and lower canines in almost all of the n group cases were not touching each other and did not restrict mandibular movement, resulting in easy attrition for the deciduous anterior dentition. 2. Longitudinal changes in the n group: Mean change of this group showed a decrease in overbite caused by the attrition of the deciduous central incisors and the continuous eruption of the maxillary second deciduous molars. Overjet also decreased, because of an increase in the maxillary anterior arch length and of backward movement in the mandibular dental arch. Individual changes were much alike in mean changes in almost all of the measured items. Arch width between canines in the maxilla and arch length in the mandible decreased in some cases, suggesting that a discrepancy would occur when the permanent incisors erupt. 3. Longitudinal changes of the r group: Mean changes showed that overbite decreased in the same pattern as the n group, but overjet did not change and the mandible did not show backward movement. The reason was that overbite in this group was deeper than in the n group at the initial examination. Moreover, deciduous molar to molar width became wider to compensate the decrease in the arch length and the perimeter. Individual changes showed that some of the r group cases had a tendency to improve, but some became worse.

The growth increments of Skeletal C1. III face during late adolescent period were investigated to estimate the possibility of earlier application of orthognathic surgery. Twenty C1. III Japanese girls, all requiring orthognathic surgery were investigated. Twenty C1. I girls were used as the control. The materials used in this study were lateral cephalometric X rays which were longitudinally taken at the age of 14 and 17 years respectively. Results were as follows: 1. The mean increments of maxilla and mandible showed no significant difference between C1. III and C1. I after the pubertal growth peak. 2. Ossification stage of the 3rd middle phalanx and the radium could be used as the maturity indicators for mandibular growth. Those were more reliable than the appearance timing of the menarche. Results are considered to be useful information for determining the timing of orthognathic surgery for Skeletal C1. III cases.

The purpose of this study was to clarify the morphological differences of Angle class II, div. 1 malocclusion between Japanese and American Caucasians by comparing their cranial base and dentofacial morphology. Materials were lateral cephalograms of 61 Japanese (30 males: mean age 12y3m and 31 females: mean age 12y10m) and 67 American Caucasians (27 males: mean age 13y6m and 40 females: mean age 13y) with Angle class II, div. 1 permanent dentition. Results were as follows: 1. The anterior cranial base length in Japanese with Angle class II, div. 1 malocclusion was significantly shorter than that of American Caucasians. 2. The maxillary length in Japanese with Angle class II, div. 1 malocclusion was significantly shorter than that of American Caucasians. 3. Less than SNA, less than SNB and less than ANB showed no significant difference between Japanese and American Caucasians with Angle class II, div. 1 malocclusion. 4. The whole mandibular length in Angle class II, div. 1 malocclusion of Japanese males and American males showed no significant difference. But the mandibular body length of Angle class II, div. 1 malocclusion in Japanese females was significantly shorter than that of American ones. 5. No significant difference was observed in gonial angle when the two groups were studied. 6. As compared with American Caucasians, the backward rotation of the mandible was evidently observed in Japanese with Angle class II, div. 1 malocclusion.

The purpose of the present study is to investigate the morphological features of open bite patients who have also disharmony of anteroposterior relations between maxilla and mandible. Lateral head films of 40 adult females with open bite were used. The samples were classified into three groups by ANB angle. Three groups were as follows. 1. Type I open bite (12 subjects, 1 degree less than or equal to ANB less than or equal to 4.5 degrees). 2. Type II open bite (13 subjects, ANB less than 4.5 degrees). 3. Type III open bite (15 subjects, ANB less than 1 degree) The normal samples was the longitudinal data of females in our department. Skeletal and dental variables were calculated and compared norm versus type I open bite, type I open bite versus type II open bite and type I open bite versus type III open bite, respectively. The following results were obtained. 1. Disharmony of the vertical dimensions in type I open bite was mainly due to long anterior lower facial height which was accompanied by large gonial angle as compared with norm. 2. There were no difference in anteroposterior position of the maxilla and nasal floor in all three open bite groups. 3. There were no difference in anterior and posterior facial height between type I and type II open bite. However, type II open bite showed the backward rotation of the mandible accompanied by over eruption of upper first molars. 4. Type III open bite showed longer anterior lower facial height which was caused by excessive mandibular growth than type I open bite. 5. Upper incisors showed labial inclination as compared with norm in all three open bite groups. However, lower incisors showed labial inclination in type II open bite and lingual inclination in type III open bite as compared with type I open bite. As a result, the inter-incisal angle was small in type II open bite and large in type III open bite as compared with type I open bite. These results suggested that the dentoalveolar factors were large in type II open bite and the skeletal factors were large in type III open bite as compared with type I open bite.