Abstract
Caries prevalence among the primary teeth and the permanent first molars was surveyed in 1000 out-patients who visited the Pedodontic Clinic of Tsurumi University Dental Hospital from May 1984 to November 1985.
The number of def teeth and the def teeth ratios were calculated in comparison with those of our previous report in 1972, and the following results were obtained:
1. The caries prevalence of the patients was more than 90% in age groups of over 3 years old.
2. The mean def-t and def-t ratios showed a consistent decrease in all current age groups, being particularly significant in the 2 to 3-year-old groups.
3. The def-t ratios of the upper primary incisors and the canines showed a re-. markable decrease in the 2 to 3-year-old groups, suggesting delayed initiation of dental caries, whereas the decrease in the primary molars was not significant and the incremental ratios with age were rather similar to the 1972 data. The dental caries prevalence of the permanent first molars showed no significant difference between the 1972 and the current groups.
4. The def-s ratios decreased on the labial surfaces of the upper primary incisors and the canines as well as in the occlusal surfaces of the primary first molars, suggesting that the early and multiple surface caries initiation, as well as its rapid progress had declined. Interproximal caries of the primary molars increased in contrast to the decrease of occlusal caries. This might be due to the improved caries detection technique and to the relative increase of contacting proximal surfaces. Although permanent first molars showed a rapid progress of caries immediately after the eruption, further investigation in older children is necessary to evaluate the caries prevalence of the first molars.
