Graduate student Saint Louis University Saint Louis, Missouri, United States
Abstract Body : Edentulism, or the loss of natural teeth, is a widespread condition with consequences that extend past the domain of oral health. This study aims to investigate the relationship between edentulism and its impact on the viscerocranium and mandible. We hypothesized that reduced masticatory strain would lead to higher variability in the edentulous sample compared to the dentulous sample since the functional integration of the cranium is disrupted.
A total of 15 human skulls were obtained through the Gift Body Program at Saint Louis University. We categorized individuals into two groups based on the degree of resorption of alveolar bone in the maxilla and mandible (dentulous n=7, edentulous n=8). Standard craniofacial measurements were taken using a digital sliding caliper. Statistical analyses were carried out using Paleontological Statistics version 4.14 (PAST). Because this small sample included both sexes, osteometric measurements were divided by the approximate area of the foramen magnum (length X breadth) for each individual, thus accounting for body size. The normalized data were subjected to Principal Components Analysis (PCA) to explore patterns of variation between the two samples.
PCA analysis of size-standardized cranial and mandibular measurements showed clear separation between groups. Dentulous individuals were less variable and tightly clustered together whereas edentulous individuals exhibited more variation. PC1 explains 87.96% of the variance. Several transverse dimensions of the face drive separation of groups along PC1. These include high loadings for bicondylar width of the mandible (0.48), bizygomatic breadth (0.44), and bigonial width of the mandible (0.39). Variables with high loadings on PC2 (accounting for 4.35% of the variance in the sample) include the height of the mandibular ramus on the right side (-0.66) and left side (-0.33), and palatopharyngeal length (0.52) (prosthion to basion).
Edentulous individuals exhibited more variation in measurements of the face and mandible than dentulous individuals. Important drivers of the separation between groups included transverse dimensions of the midface and mandible as well as the height of the mandibular rami on both sides.
The structural repercussions that accompany edentulism can have significant implications for functional aspects of the viscerocranium, as well as the aesthetics of the face. Lacking the functional integration due to the lack of masticatory strain, edentulous individuals were indeed more variable than individuals with teeth.
