Methods: A custom-made apparatus which consisted of two parts and posterior denture teeth was used to simulate the maxilla and mandible. The mandibular teeth 45-47 were prepared. Then eight interocclusal records were made between the prepared teeth and their antagonists in each of the following groups: G1: aluminum wax (Aluwax, Aluwax dental products co., Michigan, USA), G2: hydrocarbon wax compound (Beauty Pink, Miltex, Inc. York, USA), G3-G5: vinyl polysiloxane (Futar D, Futar D Fast, Futar Scan, Kettenbach, Eschenburg, Germany), G6: polyether (Ramitec, 3M ESPE, Seefeld, Germany). 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 the room temperature. Different compressive loading forces up to 1 kg were applied onto the upper part to evaluate the influence on the vertical discrepancies of the records. Two-way ANOVA was used for statistical analysis.
Results: All tested recording materials produced vertical discrepancies. However, the compressive loading force had a statistically significant influence on the vertical discrepancies (p<0.01), i.e. higher forces reduced the vertical discrepancies. When a compressive force of 1 kg was applied onto the upper part of the apparatus, the mean vertical discrepancies for G1 (11±3µm) and G2 (12±3µm) were statistically significantly higher than in the other groups G3 (1±1µm), G4 (2±1µm), G5 (0±1µm) and for G6 (-2±2µm).
Conclusion: A compressive force of 1 kg could be used to stabilize the cast during mounting procedures in an articulator using interocclusal records made of vinyl polysiloxane without changing the interocclusal relationships vertically.