There are few studies that provide information on the natural history of calculus formation. The purpose of this study is to evaluate the relationship between pre-scaling baseline calculus scores, the time since the last prophylaxis before baseline, and scores 8 weeks after scaling in a group of presumed heavy calculus formers. Scaling and polishing were completed on 203 subjects with Volpe-Manhold Index (VMI) calculus scores of 7 or higher, and the date of the last prophylaxis was noted. All were re-examined after 3 weeks. The group included 45.8% males and 54.2% females; the mean age was 41.74 (range = 24 to 72). Racial mix was 57.6% African-American, 39.9% white, and 2.5% other. The mean baseline VMI score was 24.07 (SD = 15.38, range = 7-97). The VMI scores were directly related (P = < .001) to the date of the last scaling and were highest in subjects whose last scaling was more than 2 years earlier (33.67) and least in subjects whose last scaling was less than 6 months previous (15.12). At 8 weeks the mean VMI score was 9.96 (SD = 7.30; range = 0-41). The VMI scores at this time were inversely related (P = < .05) to the date of the last scaling before baseline and were lowest in subjects whose last scaling was more than 2 years earlier (9.07) and highest in subjects with the last scaling less than 6 months previous to baseline (13.07).(ABSTRACT TRUNCATED AT 250 WORDS)