Table 1. Materials used in the study.

Materials	Compositions	Manufacturer	Lot No.
Essentia (Dark Enamel) (nano-hybrid composite)	Matrix: UDMA, Bis-EMA, Bis-GMA, TEGDMA	GC Corp.	1708182
	Filler: prepolymerized fillers, barium glass, fumed silica (filler content by volume: 65%)
Modeling Liquid (liquid used to model composite materials for direct restorations)	UDMA, 2-hydroxy-1,3 dimethacryloxy propane, 2-hydroxyethyl methacrylate	GC Corp.	1805171
G-Premio Bond (universal adhesive)	10-methacryloyloxydecyl dihydrogen phosphate, 4-methacryloxyethyl trimellitate, methacryloyloxyalkyl thiophosphate methylmethacrylate, methacrylate monomer, acetone, water, silica, initiator	GC Corp.	1901092
OptiBond XTR Primer (first step of a 2-step self-adhesive system)	Glycerol phosphate dimethacrylate, hydrophilic co-monomers, water, ethanol, acetone	Kerr Corp.	6350939

UDMA, urethane dimethacrylate; Bis-EMA, ethoxylated bisphenol-A dimethacrylate; Bis-GMA, bisphenol-A dimethacrylate; TEGDMA, triethylene glycol dimethacrylate.