A critical evaluation of the T-Scan digital occlusion analysis system

Abstract

Background: Universally used clinical armamentaria such as articulating paper, film, and silk, introduce an inter-dental material, thus leading to artefactual occlusal contact force measurements. Although the state-of-the-art high-tech T-Scan Novus similarly engages the dentition, the company promotes claims asserting T-Scan’s ability to provide reliable measurements of contact forces and their timing. Aims: A purpose of this study was to evaluate T-Scan’s capability to measure occlusal contact forces and their timing. Another purpose was to examine T-Scan’s data processing algorithm. Methods: The forces experienced by contacting crown-crown (control) and crown-sensor-crown (T-Scan) configurations with denture teeth were measured by a load cell. For statistical purposes, 21 occlusal relationships, in 0.05 mm incremental shifts of the lower member, were tested. The load cell-measured in-occlusal plane components (Fx and Fy) of the occlusal contact forces, for control and T-Scan, were isolated from the 5th chomp (of 7) during occlusion and disclusion when the bite force (Fz) was 15 N and 25 N. These Fx and Fy were used to calculate Flateral, the magnitude of the in-occlusal plane component of the occlusal contact force, Flateral. The effects on Flateral of bite force, occlusion/disclusion, and group (test/control) were analyzed using three-way repeated measures ANOVA. Results: The crown-crown Flateral forces are significantly (p<.001) larger than those of crown-sensor-crown. The presence of the sensor also alters the direction of Flateral. Additionally, the duration of a T-Scan chomp was about ½ seconds longer than control. Examination of the numerical algorithm reveals violations of basic engineering mechanics principles. Conclusion: The T-Scan system relies on engineering mechanics (statics) calculations that use artefactual occlusal contact force magnitude measurements, approximated artefactual contact point location measurements, and assumed occlusal contact force directions. As magnitude, location and direction comprise the essential defining parameters of a force vector, just one of the 3 deficiencies, by itself, is sufficient evidence to declare the impossibility of meaningful T-Scan analyses.