Effect of smoking and finishing and polishing protocol on color stability and surface roughness of resin composite

To investigate the influence of smoking and finishing and polishing protocol on color stability and surface roughness of resin composite. Seventy-two discs fabricated from supra-nanofilled composite were divided to 6 groups according to: Tobacco Product (Conventional Cigarette/CS and Heated Tobacco/HTP); and Finishing and Polishing Protocol (Control/C, Multi-step finishing system/FS, and Medium-grit abrasive bur + two-step polishing system/PS). After finishing and polishing, specimens were exposed to a total of 600 cigarettes, divided into 20 each day, simulating 30 days of smoking. Color parameters were detected using a spectrophotometer. Surface roughness (Ra) was measured before and after smoking exposure using a surface roughness tester. Surface morphology was assessed under SEM. Data were analyzed using ANOVA/Tukey’s and student t-test. For CS, ∆E values of C group was significantly higher than both finishing/polishing groups, which were statistically similar. For HTP, no significant difference in ∆E values between all groups. ∆E values of CS were significantly higher than HTP in all groups. For CS, C group showed significantly higher change in Ra than FS group; whilst no significant difference in Ra change values of PS and those of C and FS groups. For HTP, no significant difference in Ra change between all groups. Within C group, Ra change of both smoking groups was statistically similar. Within FS and PS groups, change in Ra of HTP was significantly higher than CS. Conventional cigarette smoking resulted in pronounced color change in the supra-nanofilled composite. While heated tobacco product produced an increased surface roughness. Both multi-step finishing system and two-step polishing system displayed comparable color change and surface roughness in supra-nanofilled composite.