Abstract
In view of the spread of periodontal disease, it is important to establish its preventive countermeasures. In order to establish these countermeasures, epidemiological study is necessary, and an index of periodontal disease would be an effective adjunct to this study.
A total of 70 adult females (number of effectives) ranging in age of 18 to 22 in the Tokyo Metropolis were used as subjects. Using 5 indices related to periodontal disease, Debris Index (DI), Calculus Index (CI), Oral Hygiene Index (OHI), PMA Index (PMA-I) and Periodontal Index (PI), this study attempted to measure each index, and to simplify the calculation of each index. The specific character of drugs contained in dentifrices was also studied. The following results were obtained.
(1) The first mass dental examination was carried out in 70 adult females (number of effective strength). They were divided into three groups: 21 in group A, 24 in group B, 25 in group C. Dentifrices containing Allantoin, Ipsilon, and Dihydrocholesterol were used in A group, B group and C group, respectively. The patients were instructed to brush in the morning and evening. Examination was given 4 times every week for 5 weeks. On each examination each index value was determined. The mean of each index in the first examination was 1.92 for DI, 0.35 for CI, 2.26 for OHI, 4.71 for PMA-I and 0.51 for PI.
(2) Correlation between each index of each individual was determined by a coefficient of correlation (r). The following coefficients were obtained: DI and CI was 0.42, DI and OHI was 0.89, DI and PMA-I was 0.25, DI and PI was 0.54, CI and OHI was 0.79, CI and PMA-I was 0.43, CI and PI was 0.54, OHI and PMA-I was 0.39, OHI and PI was 0.62, and PMA-I and PI was 0.54. These coefficients were highly significant.
(3) Among these coefficients, OHI showed the highest correlation with other indices classified by each index. However, since OHI is the sum total of DI and CI, DI, which showed a higher correlation than CI with OHI, was used as a base. The equation of regression to find another index from DI was sought for, and then a highly significant equation was obtained.
(4) Furthermore, coefficients of correlation between each index of each individual, a total of 105 adults in group A, 120 in group B and 125 in group C, were highly significant. From the numbers of each type of examination of the adult females (number of effectives), the difference in each index for each individual for each interval between examinations was sought, and r with each other index was also sought in each group by using DI as a base. As a result, DI and OHI showed more than 0.74 in three groups, noting a highly significant correlation. However, in all 3 groups, DI showed a different correlation with other indices excepting OHI. Therefore, the different correlation between DI and CI, PMA-I, PI was inferred to be due to a difference in efficacy of the three drugs.
