The purpose of this study was to investigate the epidemiological characteristics of gingival inflammation and the factors influencing its prevalence in first-year junior high school students. A survey of gingival inflammation evaluated by PMA index was conducted on 731 students of 6 schools in Tokushima Prefecture and the influencing factors obtained by questionnaire were analyzed.
The results were summarized as follows.
1. The prevalence of gingival inflammation was 96.4% and the PMA index showed a significant relationship to the plaque accumulation (DI-M) or calculus deposition.
2. The average PMA index of boys was higher than that of girls statistically.
3. The value of PMA index was strongly related to all factors of habitual tooth-bushing and “Regularity of between-meal eating”.
4. Using multivariant analysis, it was found that the factors related to PMA index were “Frequency of tooth-brushing” in boys and “Mouth-cleaning after between-meal eating” as well as “Frequency of tooth-brushing” in girls.