Study of correlation between plaque and gingivitis and dental caries

Abstract

The relationship between oral cleanliness and the prevalence of dental caries and gingivitis were investigated in 288 school children of 12 to 15 years residing in the suburbs of Sendai in 1969 and in 265 similar children in 1970.The scores of the Simplified Oral Hygiene Index (Greene, J.C. and Vermillion, J.R. 1964.), PMA index of front teeth (Schour, I. and Massler, M., 1948) and DMFT index were treated statistically and the following results were obtained. A close correlation between the scores of OHI-S and PMA of front teeth was present but no correlation between OHI-S and DMFT as several investigators had reported.In the study of 1970, the subjects were rated by Occlusal Plaque Index (O·P·I·), estimated by the amounts of the disclosed occlusal plaque of the four first molars. The O·P·I· scores were closely correlated with DMFT index scores, and the coefficients of correlation were 0.371 (P<0.001) in 134 boys and 0.248 (P<0.01) in 131 girls.As a highly statistical significant relationship was found between the amounts of the occlusal plaque of molars and the prevalence of dental caries, the Occlusal Plaque Index could be a useful index for estimating the status of oral hygiene in public.