The influence of lesion characteristics on application time of an infiltrate applied to MIH lesions on anterior teeth: An exploratory in vivo pilot study

Objectives: To evaluate the factors that influences the kinetics of resin infiltration of molar incisor hypomineralisation (MIH) lesions on permanent anterior teeth. Methods: Demarcated MIH lesions with homogeneous and heterogeneous lesion body appearance, Types 1 (n = 14) and 2 (n = 18), respectively, were selected. After removal of the lesion surface layer using a tapered diamond finishing bur, the lesions were etched and ethanol was applied to the lesions and it was determined if the lesion was still visible or not. Images were taken just prior infiltrant (Icon; DMG) application (T₀), during the infiltration process (T_x) and when infiltration had ceased progressing or opacity disappearance was clinically apparent (T_max). Surface-area measurements of the opacity and infiltrated area were calculated and the infiltration proportion (IP_x) was calculated over the infiltration time. Results: Type 1 and positive ethanol test lesions showed significantly lower mean T_max (3.4 min) in comparison with Type 2 and negative ethanol test lesions (9.9 min) [Student t-test/Fisher's exact test; p <.01]. A non-linear correlation was observed (R² = 0.88) indicating that the IP_x was rapid at the beginning of resin application, decreasing over time. Conclusion: In comparison with Type 1 and positive ethanol test lesions, Type 2 and negative ethanol test lesions require longer application time to infiltrate. Clinical significance: MIH-lesion type and the ‘ethanol test’ were reliable predictive factors for the application time required for infiltrating MIH lesions on permanent anterior teeth.