Caries on permanent teeth:: A nonparametric Bayesian analysis

Most earlier epidemiological investigations of dental caries have been based on cross-sectional data. Subject-specific information of dental caries in the past, and the duration of exposure of each tooth to the oral environment, are obviously important factors also influencing the presence of dental caries in the future. This has led us to consider multivariate survival models in which the information about the tooth eruption and failure times are combined to assess caries risk. A non-parametric Bayesian intensity model is presented, reflecting, on the one hand, the within subject and between subject sources of variability, and a corresponding split of variability when considering the 28 permanent teeth. We analyse a data set consisting of the dental history of 240 boys, where the observations are based on predetermined dental examinations taking place approximately once every year. Markov chain Monte Carlo integration techniques are applied in the numerical work.