Periodontal disease, tooth loss and daily life in older adults in South Australia: a longitudinal study

Background: Periodontal disease is highly prevalent among older adults. The purpose of the current study was to improve the measurement of the incidence and progression of periodontal disease in older population with a high level of tooth loss, and to evaluate the relationship between daily life conditions (systemic diseases, functional limitation and cognitive impairment) and periodontal disease. Methods: Data were from the South Australian Dental Longitudinal Study (SADLS). All participants were 60+ years. Data collection started in 1991/1992 and repeated 2, 5 and 11 years later. This study investigated the measurement of periodontal disease first by the use of periodontal disease case definitions; then the calculation of individual incidence density of periodontal attachment loss (ALOSS≥ 3mm) events. The role of systemic diseases in predicting the incidence and progression of periodontal disease was estimated after adjusting for social demographic, dental characteristics and health-related behaviour covariates using Poisson regression with robust standard errors. Marginal structural models (MSMs) with stabilised inverse-probability weights were used to estimate the direct effect of functional limitations and/or cognitive impairment on the incidence and progression of periodontal disease while controlling for other risk factors such as systemic diseases and dental behaviours. Results: Of the 801 dentate participants examined at baseline (response rate: 66.5%), 596, 365 and 234 were re-examined at the 2, 5 and 11-year follow-up respectively. Large discrepancies in the prevalence of periodontal disease were found based on three different case definitions with the same population at different time points. Both the incidence and reversal of periodontal disease were associated with the number of teeth lost at baseline and across the follow-up intervals. The mean individual incidence density of ALOSS new events was 8.3 per 1,000 tooth-years with imputed missing values due to tooth loss and loss of participants to follow-up. The individual incidence density of ALOSS new events was 2 times higher in the ‘tooth loss’ groups under the different scenarios, compared to ‘no tooth loss’ group. The predictive analyses showed that among older adults who suffered from diabetes and chronic obstructive pulmonary disease (COPD), the average ALOSS events per 1,000 tooth-years was 1.3 and 1.2 times higher respectively than for those without these diseases. The estimated direct effect of people with functional limitation increased the risk of periodontal disease progression around 1.6 times, compared with those without functional limitation; people with cognitive impairment had nearly 1.7 times greater progression of periodontal disease than those who did not have cognitive impairment; and having both functional limitations and cognitive impairment raised the progression of periodontal disease to 1.8 times compared to those who did not have functional limitation or cognitive impairment. Conclusion: Individual-level incidence density of ALOSS new events was more appropriate to estimate the incidence and progression of periodontal disease in a population with a high level of tooth loss. Diabetes and COPD were risk predictors of the incidence and progression of periodontal attachment loss, and daily life (including functional limitation and/or cognitive impairment) had a direct effect on incidence and progression of periodontal disease that was not mediated by dental behaviours or systemic diseases.Thesis (Ph.D.) -- University of Adelaide, School of Dentistry, 2016