Evaluation of fissure sealant microleakage in premolar teeth using the technique of "guided polymerization": An in vitro study

Polymerization shrinkage is one of etiologic factors of marginal leakage in the colored- tooth restorations. Guided polymerization technique has been suggested to relieve this problem. The objective of this study is to evaluate the influence of guided polymerization on microleakage of fissure sealant in premolar teeth. This in vitro study was done on 72 freshly extracted human premolars without dental caries and crack. Teeth randomly assigned into 12 subgroups of 6 each. Irradiation procedures were performed in experimental group (through tooth structure), first control group (irradiation with conventional method), second control group (irradiation with increased time) with high and low intensities of LED and QTH light curing units. Microleakage was evaluated by stereomicroscope with magnification of 40. The Kruskal-Wallis, Mann-Whitney and Logistic regression with significance of 0.05 were used for statistical analyses. The “guided polymerization” technique had no significant effect on microleakage of studied groups. None of independent variables (light cure unit, light intensity and irradiation protocols) had statistically significant effect on microleakage. Irradiation with higher intensity and lower duration (within the limits of examined intensities and durations) and just from occlusal surface using LED or QTH light curing units, in order to reduce the working time in pediatric dentistry recommended.