Abstract
This study was undertaken to examine the avoidance phenomenon of permanent tooth germs caused by the periapical inflammation of deciduous teeth in children. The orthopantomograms of 32 children (2 to 9 years of age) without caries and 74children (3 to 9 years of age) with periapical inflammation of deciduous teeth were used as materials for the investigation.
The results were as follows:
1. The average of the difference between right and left sides measured in three locations of first mandibular premolar tooth germs of 32 children without caries was mesio-distally within the range of 1.16 to 1.34 mm and vertically within the range of 0.50 to 0.63 mm.
2. The average of the difference between right and left sides of second mandibular premolar tooth germs was mesio-distally within the range of 1.08 to 1.31 mm and vertically within the range of 0.62 to 0.86 mm.
3. The avoidance of permanent tooth germs caused by the periapical inflammation of deciduous teeth was found in 19 of 74 teeth (25.7%). Concerning the region of the teeth, avoidance was found in 6 of 38 teeth in first premolar (15.8%), in 13 of 36 teeth in second premolar (36.1 %).
4. The avoidance of permanent tooth germs was frequently found in children ranging from 4 to 7 years of age.
5. Avoidance was observed in those cases that the size of the radiolucency of periapical lesion was more than 10 mm in width or length.
6. Avoidance was frequently observed in the stage of the crown formation of permanent tooth germs.
