Effect of storage in water and thermocycling on hardness and roughness of resin materials for temporary restorations

Abstract

Purpose: This study evaluated the effect of storage in water and thermocycling on hardness and roughness of resin materials for temporary restorations. Material and Methods: Three acrylic resins (Dencor-De, Duralay-Du, and Vipi Cor-VC) were selected and one composite resin (Opallis-Op) was used as a parameter for comparison. The materials were prepared according to the manufacturers' instructions and were placed in stainless steel moulds (20 mm in diameter and 5 mm thick). Thirty samples of each resin were made and divided into three groups (n = 10) according to the moment of Vickers hardness (VHN) and roughness (Ra) analyses: C (control group): immediately after specimen preparation; Sw: after storage in distilled water at 37 °C for 24 hours; Tc: after thermocycling (3000 cycles; 5-55 °C, 30 seconds dwell time). Data were submitted to 2-way ANOVA followed by Tukey's test (α = 0.05). Results: Op resin had higher surface hardness values (p < 0.0001; 25.4 ± 3.4) than the other ones (De = 4.5 ± 0.6; Du = 5.5 ± 0.4; VC = 6.1 ± 0.9). There was no statistical difference (p > 0.05) in roughness among materials (De = 0.31 ± 0.07; Du = 0.51 ± 0.20; VC = 0.41 ± 0.15; Op = 0.42 ± 0.18). Storage in water did not change hardness and roughness of the tested materials (p > 0.05). There was a significant increase in roughness after thermocycling (p < 0.05), except for material Du, which showed no significant change in roughness in any evaluated period (p = 0.99). Conclusion: Thermocycling increased the roughness in most tested materials without affecting hardness, while storage in water had no significant effect in the evaluated properties.

Review of titanate coupling agents and their application for dental composite fabrication

“…Thus, the main effect of the water is to reduce interchain interactions such as entanglements and secondary bonding. This behavior creates more volume in the matrix and enhances the movement of the chain segments, thereby resulting in the decrease of the stiffness of the material 83) . A previous study 84) inferred that storage of composites in water and artificial saliva caused plasticization and degradation of the polymer matrix and degradation of the bond between the filler and coupling agent.…”

Influence of a light‐activated glaze on the adhesion of Streptococcus sanguinis to the surface of polymers used in fabrication of interim prostheses

“…In regard to time, it was verified that the surface roughness values increased after the thermocycling, possibly due to the formation of microfissures in the polymer matrix, incurred by thermal oscillations with detachments of load particles . According to Oliveira et al, thermal variations could generate tensions in the material, harming properties such as superficial roughness . In addition, the absorption of water promotes diverse chemical and physical processes, such as hydrolytic degradation of the polymer, also contributing to the increase of roughness .…”

“…However, this fact is not in agreement with the present study because there was a numerical increase of surface energy values after thermocycling. Oliveira et al suggest that resins with high amounts of small and regular pre‐polymeric particles are not, or minimally, influenced by thermocycling …”

“…A total of 36 specimens of each resin (10‐mm diameter, 3‐mm thickness) were prepared and divided into four groups: heat‐activated acrylic resin (HAAR) (Dencor, Artigos Odontológicos Clássico LTDA); chemically‐activated acrylic resin (CAAR) (Dencor); bis‐acryl (Protemp; 3M ESPE); and bis‐GMA (Charisma; Heraeus Kulzer) composite resin. Specimens were prepared according to the manufacturers’ recommendations , and were distributed based on the type of polishing (chemical and mechanical) and thermocycling period (before and after).…”

Effect of Food Simulating Liquids and Thermo-cycling on flexural strength and surface hardness of a Resin Nano-Ceramic CAD/CAM Material

“…It also degrades the matrix/filler interface directly by hydrolytic breakdown of the silane/filler interface and the surface of the filler particles, hence decreasing the mini flexural strength and surface micro-hardness of the three tested materials. Some authors (26,27) found a decrease in the flexural strength after thermocycling, others (28) reported that thermocycling decreased the surface micro-hardness of the composite resin materials. On the other hand, others (26) found an increase in the surface microhardness of indirect composite resin materials after thermocycling and claimed that findings to the 55°C of the thermocycling water path temperature which leads to further polymerization of the surface of the composite resins.…”