In vivo and in vitro evaluation of occlusal indicator sensitivity

Indicators used to locate and eliminate occlusal disharmonies have not demonstrated specific sensitivity and reliability.

The sensitivity and reliability of articulating papers, foils, silk strips, and T-Scan systems used as occlusal indicators were investigated. The effect of saliva on the materials also was determined.

In the in vitro part of the study, a test model (mounted in an articulator and in a universal testing machine) was established with the use of maxillary and mandibular dentate casts. Articulating papers, foils, silk strips, and the T-Scan system were used to examine the loss of sensitivity of the recording materials after 3 consecutive strokes. The differences in the contact points of the test model determined by each of the recording materials were evaluated both in the articulator and in a universal testing machine. In the in vivo part of the study, occlusal contact recordings of 3 subjects were made before and after drying their mouths. The significance of the differences between the strokes repeated more than once was evaluated with the Friedman 2-way analysis of variance and Kruskal-Wallis tests. To examine the effect of the oral environment, the Wilcoxon matched-pairs signed-ranks test was applied. In all statistical analyses, the level of significance was alpha=.05.

The results demonstrated significant differences in the sensitivity of the recording materials tested (P<.001). The sensitivity of all recording materials decreased after multiple use (P<.001), and the loss of recording accuracy was significant (P<.001). All recording materials except the T-Scan were affected by the presence of saliva (P<.01).

Within the limitations of this study, the results indicated that multiple use of the recording materials tested may lead to inaccurate occlusal analysis results. It is recommended that the recording materials be used only once and that the teeth be dry during occlusal analysis.