Abstract
On the basis of the results of a 9-year secular survey,432 homogeneous individuals of Hirokamimura, Niigata Prefecture were examined for the influence of the treated or untreated condition of deciduous molar caries on first molar caries. The Treated or untreated condition of deciduous molar caries was surveyed by healthy periods up to the contraction of the caries. The unhealthy group also represented a group in which first molar of each healthy group had contracted caries during the healthy period, and the X2 test of independence was carried out between items of either the healthy group or unhealthy group and the treated or untreated condition of deciduous molars for each year.
The following results were obtained;
1. The group which contracted first molar caries within one year of the confirmation of its eruption showed no significant correlation between first molar caries and either treated or untreated condition the caries.
2. The tooth types which were contributive to the healthiness of the first molar with a strong correlation were the first deciduous molars and especially the lower jaw to a more frequent extent for the treatment and the second deciduous molar with a strong correlation for the nontreatment. The group which was healthy for one year following the eruption showed a correlation only for the mandibular second deciduous molar and a correlation for the maxillary deciduous molar for a longer healthy period.
3. The treatments which showed the greatest contribution rate in each test belonged all to the healthy group, and the treatment of the deciduous dentition deciduous molars showed a correlation with the health of the first molars. As for treatments, the application of a caries progression inhibitor was confined to the healthy group for two years, and the group which was further healthy underwent a filling and repair treatment.
4. The nontreatment which showed the greatest contribution rate in each test, C, belonged all to the healthy group, C4 belonged all to the unhealthy side, representing only the group contracting caries within two years.
