Resin-Bonded Bridge Design — ORE Part 1 MCQ

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ModerateProsthodonticsResin-Bonded Bridge DesignORE Part 1

A patient reports that their dental bridge keeps debonding. The bridge is a cantilever resin-bonded bridge (RBB) with a single retainer. What is the most important factor for long-term success of a cantilever RBB?

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Correct answer: A — Adequate enamel surface area available for bonding on the retainer

The correct answer is A. Retention of a resin-bonded bridge depends fundamentally on the strength of the bond between the luting resin and the enamel tooth surface. Enamel provides significantly higher bond strengths (≈28 MPa) than dentine (≈8 MPa). In a cantilever design with a single retainer, there is only one bonding surface; therefore, maximizing the area and quality of available enamel is critical. Mixed bonding surfaces (enamel + restorative material or dentine) fail at the strength of the weaker component. Distractors: B – Framework thickness is a design variable but subordinate to bonding surface quality. C – Occlusal contact on the pontic during lateral excursions creates harmful lever forces in cantilever bridges and reduces survival rates. D – While two retainers provide biomechanical advantages, the question presents an existing single-retainer design; the immediate solution is optimizing bonding surface, not redesign. E – Finish line design influences preparation geometry but is less critical than enamel surface area and quality.

Reference: Practical advice for successful clinical treatment with resin-bonded bridges. Br Dent J. 2023. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10570136/; Predictability of resin bonded bridges - a systematic review. J Prosthodont. 2017. https://pubmed.ncbi.nlm.nih.gov/28703151/