The significance of loading profile on the occlusion mechanics of a viscoelastic periodontal ligament analogue-supported tooth

Abstract

Background: Benchtop studies of occlusal contact forces have used teeth that were rigidly attached or supported by readily available viscoelastic (VE) materials that served as periodontal ligament (PDL) substitutes. More recent specimens have incorporated a precisely dimensioned VE PDL-behavior matched analogue. Objectives: The objectives of this study were to evaluate a modified loading protocol (step function) that is more appropriate to VE support than the previously used ramp function. The occlusion manifestations of the time-dependent behaviors (creep and recovery) of the PDL analogue were examined using the revised protocol. Methods: A mandibular 1st molar denture tooth was set into a precision-machined root/socket assembly. The PDL substitute was then cured to tight dimensional tolerances. The matching rigidly fixed maxillary denture tooth was aligned into a Class I centric molar relationship in a testing apparatus. The weighted maxillary assembly was then cycled onto and off of the load cell-supported mandibular assembly. For statistical purposes, three loading schedules were tested in 21 0.05 mm shifted occlusal relationships. Rigid attachment served as control. Results: Statistical analyses were performed on the peak values of Flateral, the net in-occlusal plane force component of the occlusal contact forces. It was found that there were statistically significant differences between: chomp-to-chomp (p < .038), PDL vs. rigid (p < .001) and loading schedules (p < .044 for PDL only). Conclusion: The loading protocol affects outcomes, and the step functions maintained consistent timing with prescribable creep and recovery periods.