Pretreatment of natural caries lesions affects penetration depth of infiltrants in vitro

Abstract

Limited evidence exists about the usefulness of ethanol or acetone application to desiccate caries lesions before resin infiltration. Therefore, this in vitro study aimed to compare the penetration depths (PD) of an infiltrant (DMG, Germany) into natural caries lesions using various pretreatments. Extracted permanent human molars and premolars showing non-cavitated caries lesions were etched (90 s, 15 % HCl gel) and stored in pooled saliva (7 days). Lesions were etched again (30 s, 15 % HCl gel), washed (30 s), air-dried (30 s), and randomly allocated to one of the pretreatments: none (negative control), air-drying (incubator, 37 °C, 24 h; positive control), once ethanol (E1), twice ethanol (E2), once acetone (A1), and twice acetone (A2). Subsequently, the infiltrant was applied for 5 min and light-cured. Ground sections were prepared for analyses of lesion depths (LD) and PD using confocal microscopy. Median LD (Q25/Q75) of all lesions (n = 91) and lesions ≥500 μm (n = 57) were 629 (395/798) and 731 (638/876) μm, respectively. When all lesions were analyzed, no significant differences between various pretreatments could be observed (p > 0.05, Kruskal-Wallis). For lesions ≥500 μm, significantly deeper PP was observed in groups PC, E1, A1, and A2 compared with NC (p < 0.05; Mann-Whitney), but not after adjustment for multiple comparison (p > 0.05). Application of either ethanol or acetone, followed by air-drying, is suitable to prepare caries lesions for resin infiltration in vitro. This paper shows that proper drying is an important step prior to caries infiltration.