Dental Cement Selection — ORE Part 1 MCQ

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ModerateDental MaterialsDental Cement SelectionORE Part 1

A patient presents for cementation of a porcelain-fused-to-metal (PFM) crown on a vital upper molar. The clinical crown height is short (limited supragingival tooth structure) due to prior restoration or natural tooth anatomy. Which of the following cement types provides the best retention for this restoration?

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Correct answer: A — Resin-modified glass ionomer cement (RMGIC)

Explanation lettering: D = shown as C · E = shown as D · C = shown as E

RMGIC (option A) is the optimal choice for a PFM crown on a vital tooth with short clinical crown because it provides retention through both adhesive bonding and mechanical interlocking. When the clinical crown is short, the available axial surface area is reduced, so conventional cements (B, C) that depend solely on mechanical fit are disadvantaged. RMGIC chemically adheres to tooth mineral (calcium) and also bonds to the PFM metal through oxide film adherence, providing superior retention despite compromised preparation geometry. Temporary ZOE (D) lacks strength for definitive cementation. Conventional GIC (E) is weaker mechanically than RMGIC and less reliable for high-retention situations. Contemporary peer-reviewed evidence ranks resin-based and RMGIC cements as providing superior retention for metal-ceramic crowns compared to zinc-based cements.

Reference: Crisp et al. (2009). Retention of metal-ceramic crowns with contemporary dental cements. Journal of Prosthetic Dentistry. https://pubmed.ncbi.nlm.nih.gov/19723946/