Adjusting estimates of alveolar bone loss for missing observations: Developing and testing a general model

The occurrence of missing teeth is a vexing and growing problem in epidemio logical studies of dental disease. The number of units of measurement (i.e. , teeth/tooth sites) varies between persons and may affect summary statisti cs in descriptive studies as well as in analytical studies. The purpose of the present study was to develop a general model to adjust summary statisti cs for missing teeth. The proposed method was applied to alveolar bone loss in current smokers, former smokers, and non-smokers, from 45 to 64 years o f age (n = 812). Alveolar bone loss was measured on bitewing radiographs. T he adjustment method was based on the assumption that the probability of lo sing a tooth was an increasing function of alveolar bone loss. The main fin ding of the present study was that mean alveolar bone loss increased after adjustment for the number of missing teeth. This increase was larger for cu rrent smokers than for non-smokers, indicating that the effects of smoking were slightly underestimated when missing sites were ignored. Further resea rch is required for the model to be applied to other data, estimating diffe rent types of dental disease with various degrees of disease prevalence and various numbers of missing teeth, and for validating the adjustment method by means of longitudinal data.