[Eruption of lateral segments of permanent dentition--differences between right and left sides]

The following results were obtained from a study on differences in eruption of the lateral segments of permanent dentition; that is, 3 (canine), 4 (first premolar), and 5 (second premolar). This study has been conducted for 9 years and 6 months on the same individuals (30 males and 29 females, aged between 6 years and 15 years and 6 months). Every 3 months, oral examinations using dental models of the upper and lower jaws were performed. In studying eruption order, teeth in the lateral segment were treated as a group. Replacement period started with the initial eruption of any of the teeth listed above and ended with the eruption of the last tooth in the group. comparisons were made between right and left lateral segments. Results 1. In the upper jaw of males, eruption orders 4----3----5, 4.3----5, and 4----3.5 were dominant in 76.90% of the right sides and 77.78% of the left sides. Corresponding percentages for females were 56.00% for the right and 57.90% for the left side. The difference between right and left sides was 0.8% in male subjects and 1.69% in female subjects. Dominant types of eruption order in the lower jaw were 3----4----5, 3.4----5, and 3----4.5. In males, these types occurred in 77.77% of right sides and 82.29% of left sides. Corresponding percentages for females were 96.00% for the right and 99.99% for the left side. The difference between right and left sides was 11.52% in male subjects and 3.99% in female subjects. 2. Initiation of replacement period varies according to eruption-order type.(ABSTRACT TRUNCATED AT 250 WORDS)