Effect of etching on laser fluorescence values in sealants

Use of DIAGNOdent (LF, Kavo, Biberach, GR) to detect caries beneath a sealant is suggested. Objective: To assess the effect of 35-37% phosphoric acid-etching products on LF readings before and after placing sealants on posterior extracted teeth and to determine its effect over time through use of thermo-cycling. Methods: 72 extracted human posterior caries free teeth were visually selected and randomly assigned to 6 groups. Each tooth was cleaned using a toothbrush. 6 different brands of etchants (e) were selected: Acid Etch, Bosworth, US. (e1), Etch 35 Gluma GR. (e2), Etch ZenithDental US. (e3), Etch, Premier US. (e4), Total Etch Ivoclar Vivadent AG. (e5). Enamel Etch Temrex US (e6). A clear sealant (Helioseal Clear Chroma, Ivoclar Vivadent AG) was selected and applied according to manufacturer's instructions. LF peak values were obtained at four different times: before, after etching, after sealant placement, and after thermo-cycling. Two-way ANOVA test was used (5% significance level). Results: There were no significant differences at baseline of LF readings between all groups. After etching, differences in LF values as compared to baseline was either significant or marginally significant (p-value 0.05 - 0.10): Mean values for each were: e1(4.3±2.6), e2(6.8±6.3), e3(2.3±1.6), e4(7.3±7.9), e5(33.3±36.7), e6(78.5±20.3). e1, e2 and e3 were not significantly different. After etching and after sealing, e5 had significantly higher LF values than e1. For all time combinations, e6 had significantly higher LF values than e1, e2, e3, and e5. Also, e5 had significantly higher values than e3. After etching, e5 had significantly higher values than e4. For after etching e5 had also significantly higher values than after sealing and after thermo-cycling. Values for after etching and after sealant for e6 were significantly higher than after thermo-cycling. Conclusion: Some etching products resulted in false-positive readings even after thermo-cycling. Further research should investigate if this effect may decrease over time.