https://www.selleckchem.com/products/ve-822.html eviation cement thickness values before and after polymerization were 157 ±27 μm and 147 ±27 μm for lithium disilicate and 162 ±53 μm and 147 ±52 μm for zirconia. Smaller cement thickness was found after polymerization (P less then .001), whereas no significant difference was found in cement thickness between materials (P=.144). No changes were noted in marginal discrepancy and cement thickness as a result of the fatigue loading. CONCLUSIONS The difference in the volumetric polymerization shrinkage of cement between lithium disilicate and zirconia veneers was not statistically significant. Polymerization shrinkage resulted in smaller marginal discrepancy and cement thickness for both veneer materials. STATEMENT OF PROBLEM Information regarding the shrinkage kinetics and monomer conversion of dual-polymerized conventional and self-adhesive resin luting agents (RLA) in situ is lacking. PURPOSE The purpose of this in vitro study was to evaluate the shrinkage strain and ratio of 1 conventional and 1 self-adhesive RLA by using fiber optic sensors based on Bragg gratings and Vickers hardness in the root canal. MATERIAL AND METHODS The root canals of 34 single-rooted premolars were endodontically treated and assigned to 2 groups according to the RLA RelyX ARC (ARC) and RelyX U200 (U200). Two Bragg grating sensors were attached to fiber posts (n=10), and both post and RLA were placed inside the root canal so that shrinkage strain and ratio values could be measured at the cervical and apical root thirds. For hardness analysis (n=7), two 1-mm-thick slices of each root-third (cervical and apical) were obtained, and 4 indentations were made on the RLA layer. The shrinkage strain and rate, as well as hardness data, were evaluated by using 2-way repeated-measures ANOVA followed by the Bonferroni post hoc test when a significant interaction between factors was detected (α=.05). RESULTS The shrinkage strain and rate values of both RL