Chewing ability in an urban and rural population over 40 years in Shandong Province, China

This study aimed to assess chewing ability related to dental status. One thousand four hundred sixty-two Chinese subjects over 40 years, dentate in both jaws, were categorized in a hierarchical functional classification system with and without tooth replacements. Chewing ability was analyzed using multivariable logistic regression including five dental conditions (a parts per thousand yen10 teeth in each jaw'; 'complete anterior regions'; "sufficient premolar regions' (a parts per thousand yen3 posterior occluding pairs (POPs)); 'sufficient molar regions' (bilaterally a parts per thousand yen1 POP); and tooth replacement), adjusted for six background variables. Likelihood ratios for chewing problems were assessed at each level of the hierarchical classification system based on these dental conditions. Seventy-eight to 91 % of subjects reported no or minor chewing problems. The conditions 'a parts per thousand yen10 teeth in each jaw', and 'complete anterior regions' were not associated, whereas 'sufficient' premolar regions' and 'sufficient molar regions' were associated with chewing problems (Ors, 0.33-0.58). If classified hierarchically, the condition 'a parts per thousand yen10 teeth in each jaw' was relevant for chewing problems (likelihood ratios 3.3-3.7). 'Sufficient premolar region' and 'sufficient molar region' were relevant to reduce the likelihood ratios for having chewing problems (both approximately with a factor 2), both for soft and for hard foods. Subjects with artificial teeth added had similar chance for chewing problems compared to counterparts with natural teeth only. However, if comparing replaced teeth with natural teeth, subjects with tooth replacement showed higher chance for chewing problems. Chewing ability was strongly associated with dental conditions. The presence of at least 10 teeth in each jaw had highest impact on chewing ability.