The incidence of dental caries in the primary molar teeth of young children receiving National Health Service funded dental care in practices in the North West of England.

INTRODUCTION: A prospective cohort study was undertaken to describe the incidence of dental caries, as recorded by GDPs, in the primary molar teeth of children aged approximately 3-6 years attending general dental practices in the North West of England.
METHOD: Detailed dental records of children aged 3-6 years attending 50 general dental practices were assembled over a period of three years. Data from these records were analysed to estimate caries incidence rates at the subject and tooth level.
RESULTS: The study population consisted of 739 children aged between 2.8 and 6.2 years; 620 children (84%) were caries free at recruitment. The incidence of developing a first carious (into dentine) lesion in caries free children increased with age. At age four the incidence of the first carious lesion was 9.5 per 100 person years and at age seven it was 19.6 per 100 person years. The tooth specific incidence of caries was found to be approximately 5-6 times greater in children with caries at recruitment than in caries free children. A sub-analysis on 566 children that were followed for more than two years revealed that of 486 children caries free at recruitment 132 (27%) developed caries in their primary molar teeth. By contrast, of the 80 children that had caries in their molar teeth at recruitment, one had eight carious molar teeth and 57 (72%) of the remaining 79 developed new cavities during the follow up period.
CONCLUSIONS: Caries incidence increases with age. There is a 5-6 times difference in the incidence of new cavities between caries free children and children with caries, irrespective of when a child developed the disease. As a consequence children with the disease and without the disease should be considered as two different populations; this has implications for care strategies applied to each population.