Dimensional Change and Imbibition of Disinfected Elastomeric Impression Materials

Objectives: The purpose of this study was to evaluate imbibition and linear dimensional change of elastomeric impression materials after immersion disinfection. Methods: One condensation silicone material (Oranwash VL, Zhermack Inc.), one addition silicone material (Silagum Light, DMG Gmbh) and one polyether material (Impregum, 3M ESPE) were studied. Specimens with special lines were made, and were immersed into a full-strength solution of 2% acid glutaraldehyde disinfectant for 30 minutes. The length of lines on specimens were measured before and after immersion disinfection following the method introduced in ISO 4823. Specimens were also weighted before and after immersion disnifection to reveal imbibition of materials. Means and standard deviations were calculated for each test. Results were compared with 1-way ANOVA, and multiple comparisons were made by use of the Student Newman-Keul's procedure. Results: For linear dimensional change, there was significant difference between silicones and the polyether material (P<0.01), but the difference between two silicones was not significant (P>0.05). Linear dimensional change of the condensation silicone and the addition silicone were 0.11% and 0.10% respectively, whereas that of the polyether was –0.10%. All materials exhibited some degree of imbibition after immersion disinfection. Results of imbibition test were 0.02%, 0.07% and 3.64% for the condensation silicone, the addition silicone and the polyether respectively, and the difference between each two materials was significant (P<0.01). Conclusion: Within the limitations of this study, all materials exhibited small linear dimensional changes after immersion disinfection, but silicones showed slight contraction while the polyether showed expansion instead. The polyether material exhibited the highest disinfectant imbibition among the 3 materials. And the addition silicone showed higher imbibition compared to the condensation silicone.