Evaluation of marginal adaptation and microleakage of all ceramic crown systems by using two commercially available luting agents - an in vitro study

Background: Marginal gap and Microleakage are known factors which influence success of Fixed Partial Denture. Thermocycling can mimic oral conditions in invitro study. Question 1: Effect of different luting agents on marginal gap and microleakage. Question 2: Effect of thermocycling on marginal gap and microleakage. Objective: This study aimed at evaluating the effects of manufacturing type, cementation and thermocycling on marginal fit and microleakage of all ceramic samples luted with two different luting agents. Methods: Eighty extracted maxillary premolars were prepared for full-coverage crowns and were divided into four groups. Group 1and 2 : Heat pressed lithium-disilicate copings and crowns, Group 3and4 : CAD/CAM-fabricated ZrO2 copings and crowns. Copings were made following standard techniques, and groups were assigned cementation with resin modified glass-ionomer luting cement self (A) or adhesive resin cement (B). The marginal gap before cementation, after cementation and after thermocycling was measured using image analysis software. After marginal gap measurement, all samples are immersed in basic fuchsin solution, sectioned mesiodistally. The surface of each section was digitally photographed under a stereomicroscope. Microleakage was scored using a five-point scale. Data were statistically analysed using 2-way ANOVA, Kruskal-Wallis, and Mann-Whitney U tests. Results: The mean marginal discrepancy values for all ceramic pressable copings and crown were more after cementation than before cementation (p=0.0). The mean marginal discrepancy values for all ceramic pressable copings and crown were more after thermocycling than after cementation (p=0.10). Samples luted with resin cement showed less marginal gap than samples luted with resin modified GIC (P=0.10).CADCAM samples showed less marginal gap than pressable samples (p=0.2). Self-adhesive resin cement (A) showed a lower level of microleakage than resin modified glass-ionomer luting cement (B) in all groups (P = 0.029). Microleakage scores of ‘0’ were 83% for 1A, 50% for 1B, 50% for 2A, 16% for 2B, 33% for 3A and none for 3B. Conclusion: Marginal discrepancy and microleakage varied with cement type. Lower levels of microleakage were recorded with self-adhesive resin cement, while CAD/CAM-fabricated ZrO2 copings showed smaller marginal discrepancy and less microleakage in comparison to pressable samples.