Effect of Immediate Dentin Sealing and Hydrothermal Aging on Bond Strength of Lithium Disilicate Glass-Ceramic: (In-vitro Study)

Abstract

Objectives: Immediate dentin sealing had been suggested immediately after tooth preparation, it is critical to know the affect of this technique on bond strength of ceramic restorations that used widely for aesthetic reason. So, the aim of this study was to evaluate the effect of immediate dentin sealing technigue on bond strength of glass ceramic and comparing with delayed dentin sealing, and to evaluate the effect of hydrothermal aging that used to mimic the oral condition on bond strength of ceramic to dentin.

Materials and Methods: Twenty extracted human premolars (N=20) were collected and divided into two groups. One group (n=10) for immediate dentin sealing (IDS) while the other group (n=10) for delayed dentin sealing (DDS). The occlusal coronal third of the crowns were trimmed and removed to expose flat superficial dentin surfaces. Dentin surfaces of IDS group were etched and sealed immediately after preparation with universal bonding system (ALL-BOND UNIVERSAL^®). Provisional restorations were made using (PRO-V FILL^®). Twenty discs made of lithium disilicate glass–ceramic (IPS e.max Press) were bonded to the dentin surfaces using resin cement (Variolink N). Each group was subdivided into two sub-groups (n=5) according to the hydrothermal aging protocol (with and without aging). Specimens were tested for micro-shear bond strength using a universal testing machine (Testometric M350-10KN) at 1mm\min until failure occurred. Data were analyzed using (T-Student) test for comparison of mean micro-shear bond strength between groups (α=0.05).

Results: The mean value of micro-shear bond strength in IDS group was significantly higher than those for DDS group before aging. No significant differences were found between two sealing groups after aging. The mean value of μSBS before Hydrothermal aging was statistically significantly higher than those after aging in two sealing groups (p < 0.05).

Conclusions: IDS can improve bond strength of lithium disilicate glass-ceramic discs to dentin before aging. Hydrothermal aging significantly reduced bond strength values of two sealing groups.