Dental Scaling Decreases the Risk of Parkinson's Disease: A Nationwide Population-Based Nested Case-Control Study.

The protective effect of dental scaling in Parkinson's disease (PD) remains inconclusive. The aim of this study was to analyze the association between dental scaling and the development of PD. A retrospective nested case-control study was performed using the National Health Insurance Research Database of Taiwan. The authors identified 4765 patients with newly diagnosed PD from 2005 to 2013 and 19,060 individuals without PD by matching sex, age, and index year. In subgroup 1, with individuals aged 40(-)69 years, individuals without periodontal inflammatory disease (PID) showed a protective effect of dental scaling against PD development, especially for dental scaling over five consecutive years (adjusted odds ratio = 0.204, 95% CI = 0.047(-)0.886, p = 0.0399). In general, the protective effect of dental scaling showed greater benefit for individuals with PID than for those without PID, regardless of whether dental scaling was performed for five consecutive years. In subgroup 2, with patients aged >/=70 years, the discontinued (not five consecutive years) scaling showed increased risk of PD. This was the first study to show that patients without PID who underwent dental scaling over five consecutive years had a significantly lower risk of developing PD. These findings emphasize the value of early and consecutive dental scaling to prevent the development of PD.