Do Exostoses Correlate with Contact Disfunctions? A Case Study of a Maxillary Exostosis

A methodology to evaluate contact areas and indentations of human fingertips based on 3D techniques for haptic purposes

This paper presents a methodology to study the contact of human fingers with surfaces based on 3D techniques. This method helps to investigate the fingertip mechanical properties which are crucial for designing haptic interfaces. The dependence of the fingertip deformation on the applied forces is obtained both with theoretical and experimental approaches. The experimental procedure is based on digital measurements by 3D optical scanners to reconstruct the geometry of the fingertip impression and on force measurements by an instrumented plate. Results highlight the force-displacement trend and can be validated with a Finite Element Model (FEM), with data from literature or with measurements at a force-strain gauge. Gross contact areas, radii and work of adhesion are also detected, and results are compared with contact models available in literature.

• A sensorized plate with a thin force sensitive resistor and a dough material layer is used to measure the contact force corresponding to a specific digital imprint.

• 3D indentation maps are obtained and evaluated by comparing the 3D scan model of fingertips during imprinting with the digital model of the undeformed fingers and of the imprints.

• Force-displacement results can be validated by comparison with a developed FEM, a force-displacement gauge or literature outcomes.

Correlations between dental wear and oral cavity characteristics: Mandibular torus, palatine torus, and oral exostoses

OBJECTIVE

This study evaluates the correlations amongst mandibular torus, palatine torus, oral exostoses to dental wear/loss and temporomandibular damage.

METHODS

The sample consists of 504 skulls from the Hamann-Todd Osteological Collection; 223 African American and 281 European Americans aged between 30 and 80 years. The sample was analyzed using Pearson's Chi-square for significance of sex, age, ancestry, and wear as well as the interactions between the demographic variables and the presence of mandibular torus, palatine torus and oral exostoses.

RESULTS

Wear was statistically significant by age and sex but not ancestry. The maxillary exostoses varied significantly by age, ancestry and wear but not sex. Mandibular torus frequencies varied significantly by wear, sex and ancestry. The palatine torus varied significantly across wear groups, sex and ancestry.

DISCUSSION

The etiology of nonmetric oral cavity characteristics, mandibular torus, palatine torus and oral exostosis, is complex. The degree to which traits' presence and expression is the result of genetic and environmental interactions is not fully understood. More than age, sex or ancestry, the degree of dental wear and tooth loss influences the presence and expression of the oral cavity traits. The sample can be characterized as the presence of exostoses in higher frequencies in young African American males with little tooth loss. Males of both ancestral groups with heavy wear have higher frequencies of mandibular tori than females. The palatine torus is more common in edentulous European American females.