Effects of exposure time and exposure distance on the degree of cure in light-activated pit and fissure sealants

Abstract

ObjectivesThe study aims to measure and compare the effect of different exposure times and exposure distances on the degree of cure (DC) of light hardening resin based pit and fissure sealants. MethodsA representative selection of 13 commercial sealants brands was chosen. DC of each material (n=6) was measured in real-time by Fourier transform infrared spectroscopy (FTIR) at three clinically relevant exposure times (10, 20, 40s) and two fixed exposure distances (4mm and 7mm) between sample and light source. Data were analyzed by a multi-variant analysis and partial eta-squared statistic. ResultsFactors “material”, “exposure time” and “exposure distance” had a significant influence on the DC across all materials (ηp2=0.927,0.774 and 0.266 respectively) with “material” and “exposure time” showing the strongest effect (significance level α≤0.05). In general, an increased exposure time and reduced exposure distance between sample and light source led to increased DC for all the materials. ConclusionsDegree of cure is influenced significantly by the brand of sealant and by exposure time. In some cases it is found that DC is also affected significantly by the exposure distance. Clinical significanceOn the basis of this study, an exposure time of at least 20s and a maximum exposure distance of 4mm between curing unit and material surface is recommended.