Infiltration of natural caries lesions with experimental resins differing in penetration coefficients and ethanol...

Resin infiltration of enamel caries lesions requires materials optimized for penetration into the capillary structures of the lesion body. With increasing penetration coefficients (PC) improved penetration and caries-inhibiting properties of low-viscosity resins (infiltrants) could be observed in artificial caries lesions. The aim of the present in vitro study was to compare the penetrativity of experimental resins varying in PC and ethanol addition into natural caries lesions using this technique. Extracted human molars and premolars showing proximal white spot lesions (International Caries Detection and Assessment System: code 2) were etched for 2 min using 15% hydrochloric acid gel. After drying, the lesions were stained with tetramethylrhodamine isothiocyanate and 1 of 4 experimental resins (PC63; PC185; PC204; PC391) was applied for 5 min. The materials consisted of bisphenol-A-glycidyl-methacrylate (B), tri-ethylene-glycol-dimethacrylate (T) and ethanol (E) in ratios (B:T:E) of PC63: 25:75:0; PC185: 20:60:20; PC204: 0:100:0; PC391: 0:80:20. Excess material was removed before light curing. The teeth were sectioned perpendicularly to the lesion surfaces and unbound dye was bleached by immersion in hydrogen peroxide. The remaining lesion pores were stained with fluorescein solution. Lesion and penetration depths were analyzed using confocal microscopy (n = 60). At deep lesion sites the percentage penetration of PC204 was significantly higher compared to PC63 and PC391 (p < 0.05; Mann-Whitney test) but only slightly higher than PC185 (p > 0.05). It can be concluded that materials with high PC (infiltrants) are capable of penetrating almost completely into enamel parts of natural caries lesions in vitro. A solvent-free resin mainly consisting of triethylene glycol dimethacrylate seems to be preferable.