A Prospective Clinical Evaluation of Indirect Overlay Restorations With Different Cavity Preparation Designs in Endodontically Treated Molars: Two Year Randomized Clinical Trial

First Validation of endodontic treatment using a periapical radiograph and proper history taking.

{I}• Cavity Preparation Procedures for Comparator Group:

• Removal of any remnants of temporary filling and excess gutta percha to the level of root canal orifice.
• Removal of all undermined enamel.
• Then 1.5 to 2 mm cusp reduction will be performed for the buccal and lingual walls.
• The occlusal box will be of 2.5 mm width, 2 mm depth cavity walls and will be flared to produce a 6 degree of divergence.
• The cavity will have internal rounded angles, finished enamel with sharp non-beveled margins and smooth well-defined walls.
• Immediate Dentin Sealing and Cavity Optimization: Immediate dentin sealing will be performed through the use of a universal adhesive followed by the injection of injectable flowable resin composite. Blocking of undercuts using injectable flowable resin composite and margin elevation if required.
• The final retentive design will include occlusal clearance of 2 mm with occlusal box cavity of depth 2 mm with all margins in enamel occlusally and all dentin surfaces will be covered.

{II}• Cavity Preparation Procedures for Intervention Group:

• Removal of any remnants of temporary filling and excess gutta percha to the level of root canal orifice.
• No additional removal of the tooth structure will be performed at this step.
• Cavity optimization will be performed first.
• Blocking of undercuts using injectable flowable resin composite and margin elevation if required.
• The occlusal cavity will be restored during cavity optimization with injectable resin composite to reduce the areas of dentin exposure and preserve the remaining tooth structure.
• The dentin substitute resin composite will establish the biobase.
• An anatomical non retentive preparation design will be performed to show continuous inclined plane preparation with 2 mm cuspal reduction, concave chamfer margins, and 1 to 1.5 mm thick butt-joint preparation in the interproximal portion.
• The final cavity design will include occlusal clearance of 2 mm with total cusp coverage, with biomimetic features (anatomical, non-retentive design) with no occlusal box cavity.