Influence of loading forces on the vertical accuracy of interocclusal records.

OBJECTIVE: To evaluate the influence of loading forces on the vertical discrepancies caused by interocclusal recording materials. METHOD AND MATERIALS: A custom-made apparatus was used to simulate the maxilla and mandible. Eight interocclusal records were made in each of the following groups: G1-Aluwax (aluminum wax; Aluwax), G2-Beauty Pink wax (hydrocarbon wax compound; Miltex), G3-Futar D, G4-Futar D Fast, G5-Futar Scan (polyvinyl siloxanes; Kettenbach), and G6-Ramitec (polyether; 3M ESPE). The vertical discrepancies were measured by an inductive displacement transducer connected to a carrier frequency amplifier after storage of the records for 1 hour at room temperature. Different compressive loading forces up to 1 kg were applied onto the upper part of the apparatus to evaluate the influence on the vertical discrepancies of the records. Two-way ANOVA was used for statistical analysis. RESULTS: The compressive loading force had a statistically significant influence on the vertical discrepancies (P<.01) (ie, higher forces reduced the vertical discrepancies). When a compressive force of 1 kg was applied to the upper part of the apparatus, the mean vertical discrepancies for G1 (11+/-3 microm) and G2 (12+/-3 microm) were statistically significantly higher than in groups G3 (1+/-1 microm), G4 (2+/-1 microm), G5 (0+/-1 microm), and G6 (-2+/-2 microm). CONCLUSION: A compressive force of 1 kg could be used to stabilize the cast during mounting procedures in an articulator using an interocclusal record made of polyvinyl siloxane without vertically changing the interocclusal relationships.