To utilise novel methods to compare the fate of carious primary molar teeth and surfaces using data from a cohort study of 2,654 children aged ~5 years at baseline, undertaken by Cardiff University School of Dentistry in 1999-2003, and augmented with Dental Practice Board treatment data.
Methods:
Children were selected from fluoridated areas in West Midlands and non-fluoridated areas in South Wales. The condition of all surfaces of primary molars was recorded on 3 occasions at ~2 year intervals. Demographic attributes were also recorded.
Parametric competing risks survival modelling was undertaken on teeth and surfaces recorded as carious in the cohort study or DPB records. A data hierarchy was assumed with surfaces and teeth clustered within individuals. Marginal and cumulative incidence survival functions for exfoliation and extraction were derived to identify differences in survival arising from restorative treatment or variation in demographic or tooth- or surface-level characteristics. Odds ratios for survival to extraction by age 14 years in filled and untreated teeth and surfaces, and the expected reduction in subsequent decay-time arising from filling as a function of time of filling, were also derived.
Results:
A total of 13,098 surfaces and 5,168 teeth were analysed. Around 90% of filled teeth and surfaces exfoliated without further treatment. Over 50% of untreated teeth and surfaces required extraction by 14 years, with significantly greater odds of extraction of unrestored teeth. Early occurrence of caries increased the likelihood of extraction. Restorative treatment up to about 11 years resulted in significant savings of decay-time before loss from the mouth. Variation in demographic factors and tooth and surface parameters had limited effect on survival experience.
Conclusions:
Filling carious primary teeth significantly reduces the subsequent likelihood of extraction. The concurrent risk of exfoliation has a moderating effect on improvements gained from later treatment.