Comparative evaluation of shear bond strength at the interface of monolithic zirconia with two distinct core build-up materials: An in vitro study

The study aimed to evaluate and compare the shear bond strength (SBS) at the interface of monolithic zirconia with zirconomer (Zr) core build-up, a new type of glass ionomer cement to monolithic zirconia with composite resin core build-up material.

In vitro a comparative study.

A total of 32 disk-shaped samples of monolithic zirconia and two distinct core build-up materials: Zr (n = 16) and composite resin (n = 16) were used. The two components, monolithic zirconia with Zr core build-up and monolithic zirconia with composite resin core build-up, were bonded using zirconia primer and self-adhesive, dual-cure cement. The samples were subsequently thermocycled, and the SBS was tested at their interfaces. The failure modes were determined using a stereomicroscope. Data were evaluated using the descriptive analysis for mean, standard deviation, confidence interval, and independent t-test for intergroup comparison.

Descriptive analysis, independent t-test, Chi-square test.

The mean SBS (megapascals) of monolithic zirconia to Zr core build-up (0.74) was statistically significant when compared to monolithic zirconia with composite resin core build-up material (7.25) (P ≤ 0.001). Zirconomer core build-up showed 100% adhesive failure; composite resin core build-up had 43.8% cohesive, 31.2% mixed, and 25.0% adhesive failures.

When evaluating the two core build-up materials' bindings to monolithic zirconia, Zr and composite resin core build-up showed statistically significant differences. Although Zr has been demonstrated to be the optimal core build-up material; however, additional investigation is required to determine how it bonds to monolithic zirconia more effectively.