Caries prevalence in Western countries has declined since the 1970s, so the distribution of caries indices (DMFT/S) became positively skewed. These changes have had the effect of increasing the proportion of zeros in the distribution of dental caries indices. In the literature several models are applied to describe the nature of the index distribution and applied in multiple regression techniques to estimate the covariates of caries disease. The aim of this paper was to determine the best model to estimate the proportion of caries-free and the dependence of dmfs index to the influence of childhood socio-demographic factors (SDF). The data set from the first National Pathfinder survey of 4-year-old Children’s Oral Health in Italy was used. Negative binomial distribution (NBD) and Poisson distribution (PD), as the most common models for dental caries, were compared to the recent related zero-inflated models (ZIP and ZINB). NBD proved to be more appropriate for analyzing the distribution of caries data in children than PD (p ! 0.001). Similarly, ZINB goodness-of-fit was better (p ! 0.001) than that of ZIP, that of ZIP better than that of PD and, finally, ZINB was better than NBD. The significant background variables in bivariate analysis (parent’s nationality and educational level, pre-term birth, breast-feeding and age of tooth eruption) were considered as predictors for dmfs in the ZINB regression model. Children from parents with high educational level (mother or father) or from a father of Italian nationality had higher probability of being caries free (0.82 vs. 0.73, 0.83 vs. 0.74, 0.81 vs. 0.61, respectively). Investigation of caries distribution via new models might be useful to provide new insight into caries patterns.
Caries distribution modelling: an application on the data set from the first National Pathfinder survey of Italian 4-year-old Children / Solinas, Maria Giuliana; Campus, Guglielmo Giuseppe; Cagetti, Mg; Maida, C; Castiglia, Paolo Giuseppino; Strohmenger, L.. - In: CARIES RESEARCH. - ISSN 0008-6568. - 42:(2008), pp. 215-215.