Prevalence and severity of gingivitis in American adults.

PURPOSE To investigate prevalence and severity of gingivitis in representative American adults. METHODS Subjects (1,000) in Loma Linda, California; Seattle, Washington; and Boston, Massachusetts were examined for Löe-Silness Gingivitis Index (GI). Mann-Whitney rank sum test was used to determine significances in the GI between genders. The data among study sites and races were compared using the Kruskal-Wallis one-way ANOVA on ranks. The correlation of the GI and age was examined by the Spearman rank order correlation. Age differences among three sites were analyzed using the one-way ANOVA. RESULTS The race composition of the subjects (mean age 37.9) approximated to the 2004 U.S. Census data. The overall average GI was 1.055. Only 6.1% of subjects showed mean GI<0.50; most (93.9%) were > or = 0.50, with 55.7% > or = 1.00. There was a significant correlation (P<0.001) between the age and GI. The males' GI was significantly higher (P<0.001) than the females'; African-Americans showed a significantly higher GI (P<0.05) than other races except for the Native-Americans.