Dental caries risk in patients with chronic airway diseases using dry powder inhalers: a retrospective cohort study

OBJECTIVE: Inhalers, which are essential for chronic airway disease treatment, differ in formulations. Dry powder inhalers (DPIs) with lactose monohydrate may increase the risk of dental caries compared with lactose-free pressurized metered-dose inhalers (pMDIs). We investigated the incidence of dental caries among users of these inhaler types for chronic airway diseases. METHODS: In this study, we analyzed inhalation technique checklists and patient records at a single center from 2010 to 2018. The study included adult patients with asthma or chronic obstructive pulmonary disease who initiated inhaler usage for the first time and continued for at least 6 months. Those with preexisting dental caries, inhaler changes, or missing lung function data were excluded. We analyzed the incidence rate of dental caries during the study period, the time to the first dental caries occurrence, and the adjusted hazard ratios among pMDI and DPI users employing Kaplan-Meier survival analysis and Cox proportional hazards model. RESULTS: Of 4,092 patients, 1,381 (33.7%) and 2,711 (66.3%) used pMDIs and DPIs, respectively. The incidence rate of dental caries was 2.28 per 1,000 person-years for pMDI users and 4.53 for DPI users. DPI users exhibited a significantly shorter time to first dental caries occurrence (P = 0.029, log-rank test) with a higher 5-year caries occurrence rate (1.9% vs. 0.8%, P = 0.015) and a higher risk of dental caries than pMDI users, with an adjusted hazard ratio of 2.09 (95% confidence interval: 1.04-4.18, P = 0.037) in the multivariable Cox regression analysis. CONCLUSIONS: Patients with chronic airway disease using DPIs have a higher risk of dental caries than those using pMDIs. Thus, vigilant dental health monitoring is necessary for DPI users.