A Comparative In Vitro Analysis of Mechanical and Optical Properties of Direct, Direct–Indirect, and Injectable Composite Veneer Techniques Using Different Types of Composite

Direct composite veneers provide favorable esthetics and are a one-visit procedure, but are limited by polymerization shrinkage, chipping, and discoloration. Direct–indirect and injectable techniques have been introduced to overcome these limitations. This study compared the shear bond strength, marginal seal, and color stability of these three veneer techniques using two composite materials in each group. We randomly allocated 270 bovine anterior teeth to three veneer groups (n = 90 per group), then divided each group into three testing groups (n = 30 per group); within each testing group, we used two composite materials (15 each). We evaluated the parameters using appropriate statistical tests (p ≤ 0.05). The direct–indirect technique showed the highest shear bond strength and best marginal seal, followed by the injectable and direct techniques (p < 0.0001). The injectable technique demonstrated the greatest color stability, whereas the direct technique showed the highest color change and marginal leakage after aging (p ≤ 0.0001). Composite material had a smaller, less consistent effect than technique overall. These findings indicate that veneer fabrication technique has a greater influence on mechanical and optical outcomes than composite material, with the direct–indirect technique achieving the strongest bond and best marginal seal, and the injectable technique showing superior color stability.