Objectives: This study examined the association between chronic medication exposure and 5-year dental caries increment among older people, using a theoretical model whereby xerogenic medication is thought to lead to increased caries by either (i) chronically lowering salivary flow, thus reducing salivary buffering of plaque acids, or (ii) producing the symptoms of dry mouth, leading to symptomatic relief through the use of cariogenic drinks and foodstuffs.
Methods: Data were obtained from participants remaining at the 5-year follow-up phase of a cohort study of community-dwelling South Australians aged 60 +. Medication information was available at baseline and at 5 years, enabling only those medications taken on both occasions to be included in the analyses. Dental examinations were conducted at baseline and 5 years, and a reversal-adjusted 5-year caries increment was computed. Multivariate modelling was used to control the effects of potential confounders.
Results: Of the original sample, 528 (62.3%) remained after 5 years, with those remaining tending to be younger, healthier and less medicated than those lost to follow-up. Five-year coronal caries incidence was 66.9%. The adjusted coronal caries increment (AdjCI) was higher among males and among those taking a β-blocker or an antiasthma drug for the previous 5 years. The 5-year incidence of root surface caries was 59.3%. A lower root surface AdjCI was associated with taking daily aspirin. Of the medications shown in earlier analyses to predict dry mouth, only the antiasthma drugs were associated with higher caries experience, and they had predicted more severe xerostomia symptoms.
Conclusions: This study offers no strong evidence for a medication–caries relationship, as only one of the observed medication–caries associations was explicable in terms of the theoretical model. However, it should be acknowledged that older people taking antiasthma drugs may be at higher risk of coronal caries, possibly through measures taken for the symptomatic relief of dry mouth.