Prospective study of 5-year caries increment among children receiving comprehensive dental care in the New England children's amalgam trial

To measure the 5-year caries increment among high-risk children during their participation in the New England Children's Amalgam Trial (NECAT), and to evaluate sociodemographic factors that may account for any observed disparities. NECAT recruited 534 children aged 6-10 with at least two decayed posterior occlusal surfaces from urban Boston and rural Maine. After restoration of baseline caries and application of sealants to sound surfaces, NECAT continued to provide free comprehensive semiannual dental care to participants. The net caries increment of children who completed the 5-year follow-up (n = 429) was calculated and predictors of caries increment were investigated using multivariate negative binomial models. The majority of children (89%) experienced new caries by the end of the 5-year follow-up. Almost half (45%) had at least one newly decayed surface by the first annual visit. At year 5, the mean number of new decayed teeth was 4.5 +/- 3.6 (range 0-25) and surfaces was 6.9 +/- 6.5 (range 0-48). Time trends showed a noticeably higher increment rate among older children and young teenagers. Multivariate models showed that age (P < 0.001), number of baseline carious surfaces (P < 0.001), and toothbrushing frequency (< 1/day versus >= 2/day, P = 0.04) were associated with caries increment. Only 48 children (11%) did not develop new caries. Despite the receipt of comprehensive semiannual dental care, the vast majority of these high-risk children continued to develop new caries within 5 years. While disparities were observed by age, extent of prior decay, and toothbrushing frequency, no other sociodemographic factors were associated with caries increment, suggesting that the dental care provided during the trial reduced sociodemographic disparities in prior caries experience that were observed at baseline.