Evaluation of the value of re-wetting prior to resin infiltration of post-orthodontic caries lesions.

OBJECTIVES: Assessment of the influence of colour changes during the re-wetting process as a possible predictor for the final result after resin infiltration to mask post-orthodontic white spot lesions. MATERIALS AND METHODS: Resin infiltration (ICON; DMG, Hamburg, Germany) was performed according to the manufacturer's recommendation with the exception of repeated, at maximum three etching procedures based on the subjective decision of the dentist during a so called re-wetting process using ethanol. The masking effect by ethanol as well as after resin infiltration was evaluated by digital images taken before, for nine seconds during re-wetting and one week after treatment using CIE L*a*b* colour space. RESULTS: Twenty-nine patients (16 female) with a total of 221 lesions (ICDAS 2) were included (mean age 16 years). Mean time after debonding the orthodontic appliances was ten weeks. Colour changes during re-wetting, evaluated in the first ten patients (71 lesions) showed a significant correlation between the minimum DeltaE observed during re-wetting and the final DeltaE after resin infiltration (r = 0.65, p < 0.001; Spearman correlation). The main drop in DeltaE becomes visible after three seconds when performing the re-wetting process. Regarding the 221 lesions, resin infiltration significantly reduced the colour difference between sound and lesion areas from a baseline DeltaE (25(th)/75(th) percentiles) of 10.9 (8.2/13.2) to a DeltaE of 4 (2.1/5.8) after one week (p < 0.001). The number of etching procedures correlated significantly with baseline DeltaE (p < 0.05). CONCLUSIONS: The minimum DeltaE observed during the re-wetting process seems to be a useful predictor for the final result of resin infiltration of post-orthodontic caries lesions. More prominent lesions with higher DeltaE at baseline seem to require more erosion of the surface layer. In general, a significant and considerable clinical reduction of DeltaE could be observed. CLINICAL SIGNIFICANCE: We corroborate that resin infiltration technique is a very useful method to mask caries lesions having developed during treatment with fixed orthodontic appliances. Colour changes while re-wetting the lesions with ethanol seem to be a valuable indicator for the number of required etching procedures.