Comparison of involutional changes on maxilla and mandible

Background. Dimensions and shape of maxilla and mandible are highly influenced by the presence of teeth and force produced by masticatory muscles. As a consequence both dimensions and shape might change with aging. Aim. Our goal was to compare the extent of these changes between maxilla and mandible. Material and Methods. We examined 169 maxillae and 42 mandibles (age range 20–80 years) using digital caliper. There were 14 measures on maxilla and 11 measures on mandible. Measures were labeled as vertical, horizontal or sagittal in order to study growth in three dimensions. Bones were divided into three groups based on presence of teeth and alveolar process: group 1 — completely preserved teeth and alveolar process ; group 2 — partialy preserved teeth or alveolar process ; group 3 — all teeth lost and alveolar process completely resorbed. Results and Discussion. In both maxilla and mandible only vertical measures showed significant change with aging. On the maxilla all vertical measures in group 3 decreased when compared to group 1. Decrease ranged from 8% to 17%. Group 2 didn’t show significant changes when compared to group 1. On the other hand on mandible only those vertical measures containg alveolar process component decreased. Decrease was significant in both group 2 (ranging from 4.5 and 20%) and group 3 (ranging from 22.5 and 59%). Conclusions. Teeth loss causes vertical dimensions regression on both maxilla and mandible, whereas change of masticatory muscles function with aging plays minor role. The impact of teeth loss is more profound on mandible than on maxilla.