Background: Oral aesthetics is currently a widespread area of dentistry, and its advancement has gained significant importance. Dental ceramics are important in this regard because they not only have high colour stability and the capacity to resemble genuine teeth, but also because they are biocompatible, have good wear resistance, and are simple to maintain. A metal/ceramic pair's success is largely dependent on how well the ceramic adheres to the metal basis.

Objective: To compare the shear bond strengths of conventional glass ionomer, resin-modified glass ionomer, polyacid-modified composite, and composite resin along with the evaluation of the failure modes (adhesive, cohesive, and mixed).

Methods: In order to evaluate different restorative materials, the occlusal dentin of 28 removed human teeth was randomly divided into four groups of ten teeth each. Traditional glass ionomer cement (Group I), resin-modified glass ionomer cement (Group II), polyacid-modified composite resin (Group III), and hybrid composite resin (Group IV) are the four groups. Shear bond strength (SBS) tests were performed on the joined materials using an Instron Universal Testing Machine with a crosshead speed of 0.5 mm/min. A stereomicroscope with a 10x magnification was used to inspect the bond failure site.

Results: The mean SBS for Groups I through IV was, respectively, 4.378, 8.45, 10.74, and 15.42 MPa. The bond strength of resin-modified glass ionomer cement, polyacid-modified composite resin and hybrid composite resin were higher than the of Traditional glass ionomer cement. We observed an adhesive failure, a cohesive failure (within material and dentin) and mixed failure with these interfaces.

Conclusion: The composite restorative materials have shear bond strengths that are greater than those of composite resin but lower than those of conventional glass-ionomer and resin-modified glass-ionomer.