Abstract
<title>Abstract</title> <p> <bold>Objectives</bold> Orthodontic relapse, the tendency of teeth to return toward their pre-treatment positions, remains a major challenge and has led to widespread use of fixed lingual retainers to preserve stability. However, conventional metal-wire retainers frequently exhibit high failure rates and limited longevity. Therefore, the aim of the study was to evaluate the shear bond strength (SBS) and failure pattern of a novel veneer-assisted fixed retainer compared with a conventional wire-only retainer design. <bold>Materials and Methods</bold> Seventy-six bovine incisors were allocated into 38 matched pairs (n = 19 per group). In the experimental group, multistranded wire was embedded within prefabricated composite shells (Filtek™ P60) and bonded using Transbond™ LR. Control specimens used conventional wire-only bonding. All samples underwent thermocycling (5,000 cycles, 5–55°C). SBS was measured with a universal testing machine, and failure modes were assessed using the Adhesive Remnant Index (ARI). <bold>Results</bold> Veneer-assisted retainers demonstrated significantly higher SBS compared with controls (2.89 ± 1.53 MPa vs. 1.99 ± 1.01 MPa; p = 0.036). ARI scores of 2–3, indicating that more than 50% of adhesive remained on the enamel surface, were significantly more frequent in the veneer group (p = 0.043). <bold>Conclusions</bold> Within the limitations of this in vitro study, the veneer-based fixed lingual retainer demonstrated improved bond performance and more favorable adhesive failure patterns compared with a conventional multistranded retainer. <bold>Clinical Relevance</bold> The novel design of the lingual retainer may improve bonding behavior at the adhesive interface; however, the underlying mechanisms were not directly evaluated. </p>