Infiltrants inhibit progression of natural caries lesions in vitro.

To define the optimized material properties of caries-infiltrating resins (infiltrants), we evaluated the effects of infiltrant composition and penetration coefficient (PC) on the inhibition of the progression of natural approximal caries lesions in vitro. Non-cavitated natural enamel lesions were etched (15% HCl gel) and infiltrated for 5 min with experimental resins varying in PC (cm/sec): PC63, PC185, PC204, and PC391. As a positive control (PosC), lesions were covered with flowable composite resin, whereas untreated lesions served as negative controls (NegC). Specimens were exposed to a demineralizing solution (pH 4.95) for 400 days. Progression of mineral loss was analyzed by transverse wavelength-independent microradiography. Percentage progressions of NegC [median (25th/75th percentile), 24 (10/56)], PC63 [9 (3/39)], and PC185 [12 (9/24)] were significantly higher compared with those of PosC [1 (-8/8)], PC204 [-2 (-4/2)], and PC391 [0 (-5/9)] (p < 0.05). Thus, infiltrants with PC > 200 cm/sec are capable of inhibiting lesion progression.