I O Thomsen | PubMed Health

PubMed1999

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 epidemiological studies of dental disease. The number of units of measurement (i.e., teeth/tooth sites) varies between persons and may affect summary statistics in descriptive studies as well as in analytical studies. The purpose of the present study was to develop a general model to adjust summary statistics 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 of age (n = 812). Alveolar bone loss was measured on bitewing radiographs. The adjustment method was based on the assumption that the probability of losing a tooth was an increasing function of alveolar bone loss. The main finding of the present study was that mean alveolar bone loss increased after adjustment for the number of missing teeth. This increase was larger for current smokers than for non-smokers, indicating that the effects of smoking were slightly underestimated when missing sites were ignored. Further research is required for the model to be applied to other data, estimating different 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.

Age Factors↗

PubMed1995

Age estimation of adults from dental radiographs.

Previous studies have shown that with advancing age the size of the dental pulp cavity is reduced as a result of secondary dentine deposit, so that measurements of this reduction can be used as an indicator of age. The aim of the present study was to find a method which could be used to estimate the chronological age of an adult from measurements of the size of the pulp on full mouth dental radiographs. The material consisted of periapical radiographs from 100 dental patients who had attended the clinics of the Dental Faculty in Oslo. The radiographs of six types of teeth from each jaw were measured: maxillary central and lateral incisors and second premolars, and mandibular lateral incisors, canines and first premolars. To compensate for differences in magnification and angulation on the radiographs, the following ratios were calculated: pulp/root length, pulp/tooth length, tooth/root length and pulp/root width at three different levels. Statistical analyses showed that Pearson's correlation coefficient between age and the different ratios for each type of tooth was significant, except for the ratio between tooth and root length, which was, therefore, excluded from further analysis. Principal component analyses were performed on all ratios, followed by regression analyses with age as dependent variable and the principal components as independent variables. The principal component analyses showed that only the two first of them had significant influence on age, and a good and easily calculated approximation to the first component was found to be the mean of all the ratios. A good approximation to the second principal component was found to be the difference between the mean of two width ratios and the mean of two length ratios, and these approximations of the first and second principal components were chosen as predictors in regression analyses with age as the dependent variable. The coefficient of determination (r2) for the estimation was strongest when the ratios of the six teeth were included (r2 = 0.76) and weakest when measurements from the mandibular canines alone were included (r2 = 0.56). Measurement on dental radiographs may be a non-invasive technique for estimating the age of adults, both living and dead, in forensic work and in archaeological studies, but the method ought to be tested on an independent sample.

Adult↗