Abstract
It is important to study the change of the gingival contour and alveolus during the period while primary dentition changes to the permanent dentition. The purpose of this study was to observe the change in the gingival contour and alveolus from Dental age IIA to IIIA.50 children who had visited the Department of Pedodontics with normal occlusion, dental caries free and no periodontium participated in this study. Concerning the plaster casts of each of these participants from Dental age IIA to IIIA, the following evaluations were made.
1. level of the gingival margin in the buccal aspect.
2. horizontal and vertical distance from the gingival margin to the highest point of gingival convexity and free gingival groove.
3. level of the alveolus.
These evaluations were made on the left maxillary and mandibular teeth at the bucco-mesial angle, the lowest level of the gingival margin, the bucco-distal angle and the gingival papilla. A three-dimensional instrument (Mitutoyo Co., Ltd. Japan) was used for the evaluation. Furthermore, for the longitudinal examination, a standard plane was determined by the distal marginal ridge of the left and right second primary molars and the mid point of the primary canine.
The results were as follows;
1. The lowest point of the gingival margin was observed in the maxillary primary canine and mandibular primary first molar. From dental age IIA to IIIA, no change was observed in the level of the margin gingiva, but with the eruption of the permanent dentition, the lowest level of the gingival margin increased.
2. The horizontal distance from the gingival margin to the highest point of gingival convexity showed no major change from Dental age IIA to IIIA, but the vertical distance showed tendency toward slight increase.
3. The free gingival groove was observed on plaster casts and was clearly shown in the posterior position. From dental age IIA to IIIA, the eruption of the permanent dentition, groove was not observed clearly.
4. An inter dental groove was observed on the primate space and was clearer in the maxillary than in the mandibular. From dental age IIA to IIIA, groove was not observed clearly.
5. Close to gingivobuccal fold the anterior alveolus was concave in the palate and there was swelling in the posterior. From Dental age IIA to IIIA, the anterior alveolar was concave in the palate or lingually more clearer.
