Impact of altering the dispensing methods of resin-based cements on their physical and bonding qualities.

STATEMENT OF PROBLEM Despite the advances in dental cements a significant gap remains in understanding how different dispensing and mixing techniques impact the physical properties of resin-based cements. PURPOSE The purpose of this in vitro study was to investigate how the physical properties, shear bond strengths (before and after thermocycling), and film thickness of resin-based cements change based on the dispensing and mixing methods. MATERIAL AND METHODS Eight different resin-based cements were evaluated, and specimens were prepared for each method (n=14) by following International Organization for Standardization (ISO) standards. The specimens were desiccated and immersed according to the ISO standard, and measurements were made to determine water sorption, solubility, mass change, and film thickness. Finally, specimens were thermocycled (5-55˚C for 20 000 cycles), and shear bond strength was evaluated. Statistical analysis was then performed with the 1- and 2-way ANOVA and the Tukey post hoc test (α=.05). RESULTS For Variolink Esthetic (automix, 30.03 µg/mm3), the Wsp was 74.8% greater than Variolink II (hand mix, 17.18 µg/mm3) and 682.3% more soluble (P<.05). The least soluble resin-based cements were RelyX Unicem (3.83 µg/mm3), RelyX Unicem 2 (2.22 µg/mm3), and Variolink II (2.43 µg/mm3). PANAVIA SA automix and G-CEM LinkAce automix had twice the film thickness as their hand mixed counterparts (P<.05). Thermocycling reduced the shear bond strength for most resin-based cements. RelyX Unicem (3.94 MPa), Variolink II (8.52 MPa), and G-CEM Capsule (5.02 MPa) demonstrated significantly higher shear bond strength compared with their automix counterparts (P<.05). CONCLUSIONS The dispensing methods were found to significantly impact the properties of resin-based cements. Variolink II demonstrated the lowest water sorption and highest shear bond strength among the cements tested. RelyX in both mixing methods exhibited a low solubility rate. Additionally, RelyX showed consistent thickness, regardless of the different dispensing methods.