Influence of Thermal Cycling on Resins that Simulate Gingival Tissues

Objectives: The objective of this study was to compare the effect of thermocycling (TC) on color change, surface roughness, surface loss and amount of biofilm deposited of 3 restorative systems (RS) that reproduce the color of gingival tissues [two nanohybrid composites (A and B) and a giomer (C)].
Methods: Three groups (n=10) were compared before and after thermocycling, which was performed with a total of 5.000 cycles from 5°C to 55°C, during 30s of immersion in each bath and with transfer time of 3 seconds. Thirty specimens were read before and after TC, using an optical profilometer to evaluate surface roughness and surface loss, while spectrophotometers evaluated color stability. Biofilm formation were tested with 12 groups (n=5) (control and TC to each restorative systems) that was read after 3 and 24h by safranin staining.
Results: A significant color change was detected for restorative systems (p<0.05), with A (8,241±1,291), B (7,69±1,879) e C (7,998±1,776), however, without significance difference between them. ANOVA did not detect difference in surface loss (p=0.708). A greater roughness was observed in all specimens were submitted to thermal cycling without difference between the groups (p>0.05). For biofilm quantification, after 3 and 24h, ANOVA detected significance for the interaction of thermal cycling and restorative systems (p<0.05 and p<0.05, respectively) without significance in restorative systems (p>0.05) in 3 hours. In 24 hours, the group with low deposition of biofilm were the restorative system B after thermal cycling.
Conclusions: All restorative systems presented color changes after thermal cycling; higher roughness was observed after thermal cycling for all restorative systems tested, without significant surface loss; The group with low deposition of biofilm was the restorative system B after 24 hours.