An investigation into the effect of a resin infiltrant on the micromechanical properties of hypomineralised enamel

Summary Background Resin infiltration may alter the mechanical properties of enamel hypomineralised lesions ( HL ); however, variable surface layer ( SL ) thickness may affect resin penetration. Aims To determine the thickness of the SL of HL and to investigate the effect of resin infiltration on the mechanical properties of HL . Design The thickness of the SL over HL was determined using polarised light microscopy. Etching time using 15% HC l gel to remove the SL of 52 samples was determined. Selected HL and control areas of 21 teeth were infiltrated with Icon ® resin infiltrant, and cross‐sectional Knoop microhardness ( KHN ) measurements were recorded before and after resin infiltration. Results Ninety‐six point five per cent of HL had a detectable SL with mean thickness of 58 ± 29 μ m. Application of HC l for 120 s produced a mean MIH erosion depth of 58 ± 12 μ m. Eleven of 21 samples had evidence of infiltration using visual examination. The infiltrant penetrated some of the HL leading to an increase in KHN (111 ± 75 KHN ) which, when compared to adjacent non‐infiltrated HL (96 ± 52 KHN ), was not statistically significantly different ( P = 0.56). Conclusions There was marked variation in the SL thickness of HL . Resin infiltration of HL did not increase microhardness significantly.