New measure of functional tooth loss for successful Oral ageing: a cross-sectional study

Background This cross-sectional study evaluated the impacts of functional tooth loss on oral health-related quality of life (OHRQoL) among elderly people compared with the impacts of several common indicators of oral health. Additionally, the cut-off of functional tooth loss needed for a better OHRQoL was investigated to establish a new measure for successful oral ageing. Methods Data from people aged 65–74 were extracted from the Fourth National Oral Health Survey in Sichuan, China. Functional tooth loss was defined as both natural tooth loss and nonfunctional teeth, such as third molars, residual roots, and removable dentures. The cut-offs of tooth loss were first identified as 12, based on the previous definition of functional dentition (≥20 natural teeth except the third molars), and 14, 16, or 18 for further investigation. OHRQoL was evaluated by the standardized Geriatric Oral Health Assessment Index (sGOHAI) score. Logistic regression was performed to estimate the impacts on OHRQoL. Additionally, subgroup analyses were conducted using the stratified chi-square test to explore the effect of functional tooth loss at each position. Results The mean GOHAI score of the 744 participants was 48.25 ± 7.62. Elderly people who had lost ≤12 functional teeth had greater odds of reporting a higher sGOHAI score than those who had lost more functional teeth (odds ratio (OR) 1.49, 95% confidence interval (CI) 1.05–2.11). No significant difference in the sGOHAI score was detected between people who had lost 13–16 functional teeth and those who had lost ≤12 functional teeth (0.61, 0.35–1.07). The loss of second premolars and first and second molars had great impacts on the sGOHAI score when ≤12 or ≤ 16 functional teeth had been lost. Conclusions Compared with natural tooth loss, functional dentition and occluding pairs, functional tooth loss can be a better indicator of OHRQoL in the elderly population. Sixteen remaining functional teeth seem to be sufficient to maintain good OHRQoL and successful oral ageing despite that number being previously acknowledged as ≥20 teeth.