Pressure analysis during impression-making procedure with various tray designs using a digital occlusion analyzer: An in vitro study.

Purpose: The purpose of this study was to evaluate the pressures generated under various relief conditions during impression-making using the digital occlusal analyzer.

Materials and methods: A customized device and impression trays were designed to measure pressure during impression-making. The left half of the tray consistently had a 0.5 mm relief without vent holes as the control group, while the right half featured varying relief and vent hole designs, resulting in six different trays. Two impression materials (Materials A and B) were loaded onto each tray, and relative pressure was measured using the digital occlusal analyzer (T-Scan Novus, Tekscan, Inc.). The pressure-reduction ratio of each experimental side was calculated. Two-way analysis of variance (ANOVA) was used to evaluate the effect of relief conditions and impression materials on the pressure-reduction ratio, followed by post hoc multiple comparisons with Bonferroni adjustment (α = 0.05).

Results: The pressure-reduction ratio was significantly influenced by both impression material and relief amount (p < 0.001), with a significant interaction between the two factors (p < 0.001). In Material A, pressure reduction was significantly greater at 3 mm compared to 1 and 2 mm, whereas in Material B, pressure reduction increased progressively with greater relief amount. Regarding vent hole design, both impression material and vent hole configuration significantly affected pressure reduction (p < 0.001), with no significant interaction (p = 0.767). Designs with smaller but more widely spread vent holes demonstrated significantly greater pressure reductions, with significant differences observed only between the single-hole design and the two- or five-hole designs.

Conclusions: Pressure reduction during impression making was influenced by both the viscosity of the material and the pressure-relief tray design. Forming vent holes yielded more consistent and effective results than adjusting the tray relief amount, highlighting the importance of a comprehensive approach that integrates both impression material selection and the application of various pressure-relief tray designs.