Morphometric Evaluation of Eva Point in Dry Skull Specimens

Eva point is a Y-shaped convergence of stress lines forming a bony protuberance on the medial surface of the mandibular ramus located along the temporal crest.

Objective: The objective of this study was to elucidate which morphometric measurements of the mandible may be associated with Eva point thickness.

Methods: 30 dentulous dry mandibular specimens were procured from Anatomy Division of Creighton University School of Dentistry. All measurements were made with the inferior border of the mandible parallel to the floor using Vernier calipers by three investigators. Measurements included: height of Eva point, horizontal length of the mandible, inter-coronoid distance, inter-sigmoid notch distance, inter-angular distance, maximum bucco-lingual thickness inferior to the alveolar crest of erupted third molar, maximum thickness of the mandibular fossa, and maximum medio-lateral thickness of bone inferior to the mental foramen. A stepwise linear regression was performed which estimates the beta coefficients of one or more independent variables to predict the value of the dependent variable. Two stepwise linear regression models explored the association of the morphometric measurements to the thickness of right and left eva points, respectively.

Results: The initial model had an adjusted R² of 0.256 in right Eva point. Using the stepwise linear regression the resulting model with the largest adjusted R² (0.413) retained four predictors: inter-coronoid, horizontal length, inter-sigmoid notch, and maximum thickness of the mandibular fossa. The initial model yielded an adjusted R² of 0.381 in left Eva point and the largest adjusted R² (0.509) included three predictors: inter-coronoid, inter-angular, and maximum thickness of the mandibular fossa.

Conclusion: The inter-coronoid distance and maximum thickness of the mandibular fossa are consistent morphometric measurements associated with Eva point thickness.