Effect of smoking and finishing/polishing on roughness of nanohybrid-composite

Abstract

To evaluate effect of conventional cigarette and heated tobacco product smoking and finishing/polishing protocol on surface roughness of a nanohybrid composite. Thirty-six discs (6mm diameter/2mm thickness) fabricated from nanohybrid composite (Palfique LX5, Tokuyama, Japan) were assigned to 6 groups according to: tobacco product (conventional cigarette/LM, Philip Morris International Inc., Egypt; and heated tobacco/Heets, Russet, Philip Morris International Inc., Italy); and finishing/polishing protocol (control /discs cured against Mylar strip; finishing discs/Diamond Master Kit, FGM, Brazil; two-step polishing system/DIACOMP PLUS TWIST, EVE, Germany). Prior to finishing/polishing protocols, all specimens were wet ground with medium grit finishing stone (komet, Germany) as baseline. Following finishing/polishing, specimens were exposed to 600 cigarettes/Heets (20/day) equivalent to 30 days of medium smoking behavior. Surface roughness (Ra) before and after smoking was measured using JITAI8101 surface roughness tester (Beijing Jitai Tech Detection Device Co., China). Mean differences in surface roughness were analyzed using One-Way ANOVA/Tukey's and independent student t-test. For cigarettes, change in Ra of control group was significantly higher than discs group. Change in Ra of polishing system group was statistically similar to that of control and discs groups. For heets, no significant difference in Ra between finishing/polishing groups. Within control group, no significant difference in Ra change of both smoking groups. Within discs and polishing system groups, change in Ra of cigarettes was significantly lower than Heets. Heated tobacco product smoking resulted in increased surface roughness in composite compared to conventional cigarette smoking. Both finishing discs and two-step polishing systems produced comparable surface roughness.