Effect of Hydrochloric Acid on Resin Cement Microleakage in Zirconia-Reinforced Lithium Silicate Crowns

*Vasiliki Tsakalelli
Department Of Prosthodontics, United States

*Corresponding Author:
Vasiliki Tsakalelli
Department Of Prosthodontics, United States

Published on: 2020-01-02

Abstract

Purpose: To evaluate the microleakage of different resin cement after immersion of zirconia-reinforced lithium silicate crowns (ZLS) in hydrochloric acid (HCl) solution. Materials and Methods: Forty-five extracted non-carious human molars were prepared for porcelain crowns. The teeth were randomized into three different groups according to the resin cements tested: RelyX™ UniCem (3M, ESPE), Variolink® Esthetic Dual-cure (Ivoclar Vivadent) and Panavia™ 21 (Kuraray America Inc.). Five replicates were used as a control for each of the resin cement. ZLS crowns were designed and milled from Celtra® Duo blocks using CEREC computer-aided design, computer-assisted manufacturing (CAD/CAM) system and then cemented to the prepared teeth using the assigned cement according to the manufacturers’ guidelines. The samples were thermally cycled between water temperatures of 5? and 55? for 5,000 cycles with a 15-second dwell-time after each temperature. In order to mimic one year of clinical time in a patient’s mouth, the samples of the experiment group were subjected to 91 one-hour cycles in HCl (pH 2) followed by one hour in artificial saliva; samples were submerged in artificial saliva for 91 hours. The specimens then were submerged in a 50% silver nitrate solution for 24 hours followed by a developer solution for eight hours. All samples were embedded in clear epoxy resin and sectioned in a buccolingual direction at 0.5 mm. Sections were analyzed by a stereomicroscope at a magnification of 10X. The proportion of microleakage was calculated by dividing the total length of the dye penetration by the total length of the restoration. Data were analyzed with the Kruskal-Wallis test and Mann-Whitney U test with the Bonferroni correction. Results: All experimental groups demonstrated higher microleakage scores than the control groups for all types of cement. There was no statistically significant difference in median microleakage among the three types of cement tested (p>.05). Panavia 21 group showed the highest median microleakage score (59.24%) followed by Rely-X UniCem (54.95%) and Variolink Esthetic (45.83%). Conclusion: Within the limitations of this in-vitro study, all the resin cement tested exhibited microleakage to some degree, especially when they were exposed to the hydrochloric acid solution.

Keywords

All ceramic restoration; CAD/CAM crowns; Zirconiareinforced lithium silicate; Marginal integrity; Marginal adaptation; Marginal fit; Thermocycling

Purpose: To evaluate the microleakage of different resin cements after immersion of zirconia-reinforced lithium silicate crowns (ZLS) in hydrochloric acid (HCl) solution

Materials and Methods: Forty-five extracted non-carious human molars were prepared for porcelain crowns. The teeth were randomized into three different groups according to the resin cements tested: RelyX™ UniCem (3M, ESPE), Variolink® Esthetic Dual-cure (Ivoclar Vivadent) and Panavia™ 21 (Kuraray America Inc.). Five replicates were used as a control for each of the resin cement. ZLS crowns were designed and milled from Celtra® Duo blocks using CEREC computer-aided design, computer-assisted manufacturing (CAD/CAM) system and then cemented to the prepared teeth using the assigned cement according to the manufacturers’ guidelines. The samples were thermally cycled between water temperatures of 5? and 55? for 5,000 cycles with a 15-second dwell-time after each temperature. In order to mimic one year of clinical time in a patient’s mouth, the samples of the experiment group were subjected to 91 one-hour cycles in HCl (pH 2) followed by one hour in artificial saliva; samples were submerged in artificial saliva for 91 hours. The specimens then were submerged in a 50% silver nitrate solution for 24 hours followed by a developer solution for eight hours. All samples were embedded in clear epoxy resin and sectioned in a buccolingual direction at 0.5 mm. Sections were analyzed by a stereomicroscope at a magnification of 10X. Proportion of microleakage was calculated by dividing the total length of the dye penetration by the total length of the restoration. Data were analyzed with the Kruskal-Wallis test and Mann-Whitney U test with the Bonferroni correction. Results: All experimental groups demonstrated higher microleakage scores than the control groups for all types of cement. There was no statistically significant difference in median microleakage among the three types of cement tested (p>.05). Panavia 21 group showed the highest median microleakage score (59.24%) followed by Rely-X UniCem (54.95%) and Variolink Esthetic (45.83%). Conclusion: Within the limitations of this in-vitro study, all the resin cements tested exhibited microleakage to some degree, especially when they were exposed to the hydrochloric acid solution.