Labial Inclination Research Articles

The craniofacial skeletal pattern of the South African Negro

Lateral cephalometric head film measurements on twenty-seven male and twenty-eight female adult craniums and mandibles with excellent occlusions were compared with similar measurements on Caucasoids with excellent occlusions. Among the differences between the two groups is the forward position of the short maxilla relative to the anterior cranial base in the South African Negro. The forward location of point A has been effect of increasing the ANB angle, since the relative position of point B in both groups is much the same. Unlike the American Negro, the labial inclination of the upper incisors in the South African Negro is not pronounced but is similar to the inclination observed in Caucasoids. Because of the large ANB angle, the lower incisors in the S.A. Negro (as in the American Negro) are severely labially inclined. Ramus height in the S.A. Negro is shorter than that of Caucasoids and appears to be related to the steep mandibular plane observed in the former population group.

The effects of orthodontic treatment on the periodontal patient (3) (author's transl)

This clinical case was observed on the effects of orthodontic treatment on the periodontal patient with deep over bite and labial inclination of upper or rotation, and the results obtained were as follows.1. A spaced arch or contact point of anterior teeth was improved clearly with orthodontic treatment.2. The alveolar bone loss due to orthodontic procedure was not observed on the X-ray findings at this clinical case.3. Traumatic occlusion of anterior teeth was removed according to orthodontic treatment or occlusal adjustment.

An analysis of permanent mesiodistal crown size

This article refers to the mesiodistal size of the permanent teeth and presents an effective way of locating and analyzing crown-size discrepancies. The analysis proposed contributes to a more complete study of intraoral etiologic factors and a more precise diagnosis and prognosis of the dental problem. It has been illustrated that crown-size patterns differ greatly, even among good occlusions (Figs. 1 and 2). Common to both subjects are the small premolars and molars. Favorable crown-size discrepancies (Fig. 2) usually involve smaller teeth, particularly posterior teeth, which allow flexibility for the self-correction of minor anterior space deficiencies. In contrast, the remaining figures illustrate various crown-size discrepancies and the resulting malocclusions. Irregularities associated with the size disharmonies include (1) crowding of the mandibular incisors, (2) labial displacement of canines, (3) end-to-end premolar relationships, and (4) marked labial inclination of the anterior teeth. The effects on interdigitation of discrepant teeth must be differentiated from the effects of rotations and tipping of the teeth. Fig. 5 shows Class I molar and first premolar relationships; however, there is a tendency toward an end-to-end second premolar relationship because of mesial inclination of the maxillary second premolar. The complexity of interdigitation in orthodontic treatment is emphasized by the theoretical existence of more than 22,000 billion possible combinations of crown-size discrepancies (excluding the third molars).

歯科矯正治療が歯肉炎の軽減をもたらしたと思われる3症例

Three orthodontic cases of spaced arch with the labial inclination of upper and/or lower incisors were reported. All cases were female and the age started orthodontic treatment was 15, 18 and 19 years old.Swelling of papillae and gingivitis during orthodontic therapy was observed especially at the stage of space closure. It seems that gingivitis during orthodontic therapy is related to the subclinical inflammatory status of gingiva (capillary microcopically gingiva of spaced arch was frequently found to be inflammatory, however it looks normal) before orthodontic treatmant, the food retention due to the appliance and the disturbance of blood circulation due to the compression of gingiva by tooth itself at the space closure, rather than the irritation of the appliance itself.All the gingivitis disappeared in several months after active treatment of orthodontic therapy.