Influence of infiltrant application time on the reduction of opaqueness of proximal enamel caries.

INTRODUCTION: Infiltrant resins were developed to hamper carious lesion progression and mask the whitish appearance of first evidence of caries. OBJECTIVE: This study aimed at testing the hypothesis that a long application time of resin infiltrant in proximal enamel caries improves esthetic outcome compared to the commercially recommended time. MATERIALS AND METHODS: Twenty teeth with uncavitated inactive proximal white enamel caries lesions (selected by two calibrated examiners; inter-examiner κ = 0.87) were divided into two groups (experimental and control group; n = 10) that agreed regarding lesion surface area. Lesions were infiltrated following the protocol recommended by the manufacturer (two applications, 3 min application first and another 1 min application later; control) and by the protocol tested in this study (one application of 30 min; experimental). Enamel opaqueness (esthetic outcome) was measured by a calibrated examiner (intra-class coefficient of 0.9) before and after infiltration using fluorescence microscopy. RESULTS: Reduction of enamel opaqueness was significantly higher in the experimental group (40.0% ± 18.5%) than in the control group (18.6% ± 14.9%) (P = 0.0105, one-tailed t-test; Hedge's g of 1.28, 95% confidence interval of 0.43/2.13, and power of 86%). CONCLUSIONS: It can be concluded that the application time of 30 min provides a greater reduction in opaqueness of proximal enamel lesion compared to the application time recommended by the manufacturer. The high effect size could stimulate patients to comply with the treatment time.

Natural enamel caries, dentine reactions, dentinal fluid and biofilm.

It is believed that penetration of dentinal fluid into natural enamel caries (NEC) is negligible because of the barrier created by underlying sclerotic dentine, but there are conflicting evidences on whether dentine subjacent to NEC is sclerotic or demineralized. This study aimed at investigating the relationship between NEC, subjacent dentine reactions, modification of dentinal fluid, and composition of cariogenic biofilm formed on the NEC surface. Proximal NEC (PNEC) lesions of human permanent posterior teeth were included in five experiments. Histologically, microradiographic analysis with contrast solution (MRC) in dentine revealed a decreased proportion of sclerotic dentine and an increased proportion of deep dentine demineralization compared to the classical stereomicroscopic histological analysis based on dentin color and translucency. Real-time MRC and 3D optical profilometry, and 3D microtomographic analysis evidenced a facilitated transport of modified dentinal fluid towards PNEC lesions. Cariogenic biofilm formed in vitro on the PNEC surface presented lower amounts of insoluble and soluble matrix polysaccharides when 2% chlorexidine was inserted in the pulp chamber. In conclusion, this study evidenced that dentine subjacent to PNEC is mostly demineralized, providing facilitated pathway for dentinal fluid to penetrate into PNEC and alter the composition of the biofilm formed on the PNEC surface.