Open Sandwich Technique — ORE Part 1 MCQ

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ModerateDental MaterialsOpen Sandwich TechniqueORE Part 1

A 35-year-old patient requires a direct Class II restoration on the mesial surface of the upper left first premolar. The gingival margin of the proximal box lies 1 mm below the cementoenamel junction and is entirely on dentine. Which restorative approach is most appropriate?

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Correct answer: C — RMGIC at the gingival margin with composite resin occlusally

The correct answer is **A**. A gingival margin on dentine is a recognised challenge for resin-composite bonding. In an open-sandwich restoration, RMGIC forms the cervical portion of the proximal box and composite provides the occlusal restoration. In a comparative study of Class II cavities with dentine cervical margins, sandwich techniques produced significantly better marginal adaptation than either a base technique or total-bond composite alone. Option D is plausible because composite is routinely used for posterior restorations, but it is not the best option when the tested discriminator is the dentine cervical margin. Amalgam may be durable but does not provide the adhesive, tooth-coloured sandwich approach specified here. Zinc phosphate cement and gold foil are not appropriate routine materials for this direct Class II restoration.

Reference: Dietrich T, Lösche AC, Lösche GM, Roulet JF. Marginal adaptation of direct composite and sandwich restorations in Class II cavities with cervical margins in dentine. Journal of Dentistry. 1999. https://pubmed.ncbi.nlm.nih.gov/10403459/