What are the three shapes of conservative preps?

• A. Preventive Resin Restoration (PRR)/conservative composite restoration; slot/box only; tunnel prep
• B. Full crown; Onlay; Inlay
• C. Class I; Class II; III
• D. Veneer; Crown; Implant

Answer: (A)

Conservative preps aim to remove decay while keeping as much tooth structure as possible, so the shapes used are those that minimize how much tooth is cut. The three shapes typically described are a slot or box-style preparation and tunnel preparation, plus the Preventive Resin Restoration (PRR) approach with a conservative composite restoration. PRR targets pits and fissures with a small, conservative prep and seals the area with resin to halt progression of decay, preserving tooth structure. The slot or box shape provides just enough access to a localized lesion on the occlusal surface with minimal removal, helping to maintain adjacent enamel and the marginal ridges. A tunnel prep creates an access under the enamel from a marginal ridge toward the lesion, allowing removal of decay while keeping the outer walls intact. These options are clearly more conservative than full crowns or other indirect restorations, and they differ from caries classifications or from restorations like veneers, crowns, or implants, which involve more extensive preparation.