Cantilever RBB Design — ORE Part 1 MCQ
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Correct answer: E — Single-retainer cantilever design
**A is correct: single-retainer cantilever design.** For a single missing anterior tooth, a cantilever RBB supported by one abutment is preferred. Systematic-review evidence shows one-retainer RBBs have higher survival and lower debonding rates than bridges with two or more retainers; anterior comparative data also show lower clinical failure for cantilever than fixed-fixed designs. A fixed-fixed design may appear to provide additional support, but differential mobility of two abutment teeth can increase stresses at the bonded interfaces. A three-retainer design is unnecessarily extensive and sacrifices additional sound tooth structure. A spring cantilever is a different, generally less favourable design that introduces a long flexible connector rather than the conventional single-wing cantilever RBB. A pontic without a retainer cannot be retained.
Reference: Pjetursson BE et al. A systematic review of the survival and complication rates of resin-bonded fixed dental prostheses after a mean observation period of at least 5 years. Clinical Oral Implants Research, 2017. https://pubmed.ncbi.nlm.nih.gov/28191679/