The site-specificity of supragingival calculus deposition on the lingual surfaces of the six permanent lower anterior teeth in humans and the effects of age, sex, gum-chewing habits, and the time since the last prophylaxis on calculus scores.

The hypotheses to be tested were: (i) that chewing sugar-free gum frequently and for long periods would be associated with higher amounts of supragingival calculus, and (ii) that there would be no site-specificity of calculus deposition on the lingual surfaces of the 6 lower anterior teeth. Subjects, 436 in Glasgow and 191 in Winnipeg, were scored for calculus at mesial, lingual, and distal sites on the lingual surface of each of the 6 lower anterior teeth, by the Volpe-Manhold method. They also answered questions on the time since the last prophylaxis, the frequency of gum chewing, the type of gum chewed, and the length of a typical gum-chewing episode. A subset (233) of the Glasgow subjects were scaled and re-scored for calculus 3 months later. When the data for the logarithmic transformations of the initial calculus scores were subjected to stepwise multiple-regression analysis, the only factor which correlated significantly with initial calculus scores in both cities was the time since the last prophylaxis. In the Glasgow subjects scored 3 months after a prophylaxis, there was a negative correlation between chewing sugar-free gum and calculus scores, whereas in the Winnipeg subjects, age and the chewing of sucrose-containing and sugar-free gum were positively correlated with calculus scores. Thus, the results were contradictory with respect to the first-tested hypothesis. The calculus distribution patterns were very similar in the subset of Glasgow subjects and the Winnipeg subjects, with the amounts on the lateral incisors and canines averaging 70.2% and 44.5%, respectively, of those on the central incisors. Thus, the second hypothesis was disproved.