Assessing the impact of periodontal therapy on tooth loss: a register-based longitudinal study in Denmark

Background While regular periodontal care is advocated to reduce tooth loss considerably among periodontitis patients, evidence from observational studies is often limited to small single-center studies. This study aims to quantify the effect of periodontal care on tooth extractions using comprehensive Danish register data. Methods A nation-wide register-based cohort study was conducted, encompassing 40-year-old individuals with incident periodontitis in 2001, tracked through Danish registers until the end of 2021. Receiving any periodontal care was determined annually, and the number of non-surgical tooth extractions serving as the annually varying outcome. G-estimation of structural nested mean models adjusted for time-varying confounding and loss to follow-up were employed to estimate the average treatment effect of periodontal therapy on subsequent tooth extractions. Results The study included 1,251 40-year-olds with incident periodontitis in 2001. The average follow-up from 2002 onwards was 19.1 years and amounted to 23,878 person-years. On average, participants received periodontal care in 12.1 years (SD 6.3) and lost an average of 1.4 teeth (SD 3.0). G-estimation showed that receiving periodontal therapy in a given year reduced the number of teeth extracted in the following year by 0.03 (95% CI: −0.05 to 0.00). The cumulative effect of receiving periodontal therapy for five consecutive years was associated with an average of 0.06 (95% CI: 0.03 to 0.11) less extracted teeth. This protective effect was observed regardless of the baseline severity of periodontitis. Conclusions Periodontal therapy resulted in a modest reduction in tooth extractions. The effectiveness of periodontal therapy against tooth loss seems to be considerably smaller than anticipated by earlier studies.