Utilisation of Tooth Eruption Models for Caries Clinical Trials

Objectives: To identify factors affecting tooth eruption in the Republic of Ireland (RoI) and to use these factors to develop tooth eruption models that can be incorporated into the survival analysis of teeth in caries clinical trials.

Methods: Dental maturity of subjects at baseline and the eruption patterns of permanent teeth are important considerations when stratifying children for randomised controlled trials (RCTs) of oral health products. One problem with clinical trials of caries preventive agents in children is censoring of tooth eruption times.

Most caries occurs on first and second permanent molars; in the North-South Survey of Children's Oral Health in Ireland 2002 (NSSCOH 2002) decay on their first and second permanent molars accounted for approximately 90% and 80% of decay in 15-year-olds from fluoridated and non-fluoridated areas respectively of RoI.

Analysis of cross-sectional survey data from the NSSCOH 2002 was carried out to determine which factors are associated with the timing of eruption of first and second permanent molars in RoI.

Results: Age, height, gender, medical card status, fluoridation status and dental arch were all significant with regard to the timing of eruption of first and second permanent molars. First and second permanent molars were both more likely to be erupted in children who were; older, taller, female, medical card holders (all p<0.0001) and from fluoridated areas rather than non-fluoridated areas (p<0.05). They were both also more likely to be erupted in the mandible (lower jaw) than the maxilla (p<0.0001).

Statistical modelling techniques are being applied to incorporate these factors into models for the eruption of first and second permanent molars.

Conclusions: These tooth eruption models can estimate the time of eruption of teeth in subjects of caries clinical trials that would otherwise be censored and these eruption times could be built into the survival analysis of teeth.