Objective: To conduct a systematic review on color stability of dental resin-based composites (RBC) exposed to conventional and electronic cigarettes. Materials and Methods: In vitro studies reporting on the color stability of RBC exposed to conventional cigarettes or to e-cigarettes: both Tobacco Heating Systems (THS) and Electronic Nicotine Delivery Systems (ENDS). The quality of the included studies was assessed with the QUIN tool (risk-of-bias tool for assessing in vitro studies conducted in dentistry). A systematic search, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) was performed on four (n = 4) databases (Embase, Medline, Scopus, Web of Science) for articles published until March 28th, 2022.Results: Of the 365 screened articles, 13 were included in this review. All the included articles analyzed conventional cigarette smoke (CS), four analyzed Electronic Nicotine Delivery Systems (ENDS) and two Tobacco Heating Systems (THS). In terms of study design, smoke exposure time, smoke flow, type and number of cigarettes a high variability was reported. Conclusions:The available evidence suggests that CS smoke significantly affects color stability. Electronic cigarettes show less color change that seems to be easily recovered under clinical acceptability thresholds, although evidence is scarce.Clinical Significance: Clinicians should be aware, and should therefore warn their patients, that RBCs are subjected to irreversible color change if exposed to smoke. Electronic cigarettes (both ENDS and THS) induce less color change that can be recovered with repolishing or whitening procedures.

The objective of this study was to review the experimental in vitro procedures employed to assess the color stability of resin-based composites exposed to smoke. A literature search was performed on four databases (Pubmed, Scopus, Embase, and Web of Science). The quality of the included papers was assessed with the Cochrane risk-of-bias tool (RoB 2). In total, 25 studies were selected for full-text reading, from which 12 were included in the review. The assessed variables were: dimensions, shape, time before exposure, finishing, smoke-type, exposure time, brushing simulation, color, measuring system, repolishing. A disk-shaped specimen was used in most studies (n=10) with a 2 mm thickness (n=7) in custom made devices equipped with vacuum pumps or in Vitrocell systems. Spectrophotometers were the most used devices (n=11). Color differences were quantified with ΔE (n=12), ΔE00 (n=1). The large variety of staining procedures suggests the need for standardization.