Caries resistance as a function of age in an initially caries-free population

Abstract

Using data from the Center for Oral Health Research in Appalachia Study, we examined variability in susceptibility to dental caries among children and adolescents in rural Appalachia. Among 210 participants who were caries-free at the initial visit, age at the baseline visit can be used as a proxy for the degree of caries resistance; probability of caries development at the tooth level decreased as age at the baseline visit increased. Participants who stayed caries-free for a longer period during childhood and adolescence experienced less extensive caries, as measured by the number of carious teeth. However, the probability of becoming caries-positive did not correlate with age at the baseline visit. For children between 1 and 18 years of age, there was not a "threshold age" after which a caries-free child's risk of caries onset is significantly reduced.

Figure 1.

Epidemiological characters of caries. (a) Caries prevalence at 1-year age interval at the second visit. Each point represents the proportion of participants within each 1-year age interval who developed caries at the second visit. A linear regression showed that there was no significant linear relationship between prevalence and age (p = 0.706). (b) Development rate of caries of each participant against the participant’s age. Each point represents a participant. The rate was calculated by dividing the total number of carious teeth of each participant (including both dft and DMFT) by the number of years between the 2 visits for that participant. There was no significant correlation between the rate and the participant’s age (p = 0.234) if all participants were included. However, if we included only participants who developed caries (i.e., excluding the points with rate = 0), there was a negative correlation between the development rate and age (slope = −0.058, r2 = 0.068, p = 0.0204).

Figure 2.

Association between age and the posterior caries onset probability at the individual level. Points show the means of caries probability at average ages 2 to 17; error bars indicate the 95% pointwise credible intervals (CI). There was no significant difference among the probabilities at the different ages, which indicated that age did not affect the onset probability (on a log scale, the 95%CI of the age parameter β_age is [−0.05656, 0.08052]). Because time between visits did not contribute to caries onset probability, points show values calculated without including time between visits (Tbetween in Eqs. 3,4) as covariate.

Figure 3.

Association between age and the posterior caries attack probability at the tooth level of (a) primary and (b) permanent teeth. Points show the means of a tooth’s caries probability at average age 2 to 14 yrs (primary teeth) and 4 to 17 yrs (permanent teeth); error bars indicate the 95% pointwise credible intervals (CI). On a log scale, the mean and the 95% CI of the age parameter (Eqs. 3, 4) is β_primary = −0.3353 (95%CI: [−0.3895, −0.2811]); β_permanent = −0.1674 (95% CI: [−0.1953, −0.1405]). Both parameters indicate a negative correlation between caries probability at the tooth level and the participants’ average age at the 2 visits. Because time between visits did not contribute to caries onset probability, points show values calculated without including time between visits (Tbetween in Eqs. 3,4) as covariate.