Resin infiltration of natural caries lesions.

Infiltration of non-cavitated caries lesions with light-curing resins could lead to an arrest of lesion progression. The aim of this study was to evaluate the penetration of a conventional adhesive into natural enamel caries after pre-treatment with two different etching gels in vitro. Extracted human molars and premolars showing proximal white-spot lesions were cut across the lesions perpendicular to the surface. Corresponding lesion halves were etched for 120 sec with either 37% phosphoric acid gel (H(3)PO(4)) or 15% hydrochloric acid gel (HCl), and subsequently infiltrated with an adhesive. Specimens were observed by confocal microscopy. Mean penetration depths (SD) in the HCl group [58 (37) microm] were significantly increased compared with those of the H(3)PO(4) group [18 (11) microm] (p < 0.001; Wilcoxon). It can be concluded that etching with 15% hydrochloric acid gel is more suitable than 37% phosphoric acid gel as a pre-treatment for caries lesions intended to be infiltrated.