Effect of EGCG–Methacrylate-Functionalized Resin Infiltrant on White Spot Lesions: An In Vitro Study

This study evaluated the color change (ΔE₀₀) and penetration depth (PD) of white spot lesions (WSLs) infiltrated with the resin infiltrant (Icon^®) functionalized with methacrylate epigallocatechin-3-gallate (EGCG). To introduce polymerizable double bonds, EGCG was reacted with methacryloyl chloride (EM). Subsequently, the Icon resin infiltrant (I) was loaded with neat EGCG (IE) or EGCG-methacrylate (IEM) at 2 wt% each. WSLs were created on bovine enamel blocks and treated with I, IE, or IEM. Sound and untreated enamel surfaces were used as controls (C). Infiltrant PD (%) was determined by Confocal Laser Scanning Microscopy (CLSM, n = 12) analysis. For color change (ΔE₀₀) determination (n = 14), ΔL, Δa, and Δb, half of each sample was kept sound as a reference area. The color was determined with a spectrophotometer. Data were statistically evaluated (<i>p</i> = 0.05). Surface morphology was obtained as a qualitative response variable using 3D CLSM. PD (%) did not differ statistically for I, IE, and IEM (<i>p</i> = 0.780). Groups I and IEM showed similar performance on color change (ΔE₀₀) compared to the control group, while IE exhibited intermediate results, with no significant difference observed between the untreated, I, and IEM groups (<i>p</i> < 0.001). IEM promoted the masking of the WSL color without interfering with the PD.