Effects of exposure time and exposure distance on the micro-mechanical properties of light cured...

What is it about?

Introduction: The study aimed to perform comparative measurements on the effect of exposure time and exposure distance on the micro-mechanical properties Vickers hardness (HV) and indentation modulus (E) of light cured, resin-based pit and fissure sealants. Material and Methods: Thirteen pit and fissure sealants were selected. Combinations of three clinically relevant exposure times (10, 20, 40 s) and two, fixed sample - light source exposure distances (4 and 7 mm) were tested. The HV and E of each group (n = 6) were measured with an automatic hardness indenter. Data were analyzed by a multi-variant analysis and partial eta-squared (ηp2) statistic. Results: The factor “material” had the most significant influence (significance level α ≤ 0.05) on the measured micro-mechanical properties E and HV as shown by a ηp2 statistic (ηp2 = 0.939 and 0.927 respectively). The factor “exposure time” had a significant but moderate influence on both material properties E and HV (ηp2 = 0.297 and 0.084) whereas a smaller but significant effect of the factor “exposure distance” was only observed for E (ηp2 = 0.049). Conclusions: Properties E and HV are strongly influenced by the type of sealant. On the other hand, the exposure distance had a low influence on these, whilst the exposure time had a greater influence. Exposure time and to a lesser extent exposure distance have a significant effect on the micro-mechanical properties of pit and fissure sealants. Practical Implications: We conclude these findings indicate exposure time to be more significant when considering clinical application of these materials. Keywords: Pit and fissure sealants; micro-mechanical properties; pediatric dentistry; dental materials; curing.

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