Additive vs Subtractive Manufacturing for Endocrown Fabrication: A 24-Month RCT

Overview

This randomized controlled trial (RCT) compares the 24-month clinical performance of endocrown restorations fabricated by two digital manufacturing pathways: additive manufacturing using 3D-printed ceramic-filled photopolymer resin (VarseoSmile TriniQ, BEGO) versus subtractive computer-aided design/computer-aided manufacturing (CAD/CAM) milling from hybrid nano-ceramic blocks (HC Hard Block, Shofu). Sixty endocrowns will be placed in endodontically treated posterior molars and evaluated using modified United States Public Health Service (USPHS) criteria at 6, 12, and 24 months. The trial is conducted at the Conservative Dentistry Department, Faculty of Dentistry, Cairo University.

Post-endodontic rehabilitation of extensively damaged posterior molars using endocrowns represents a minimally invasive alternative to conventional crown-plus-post-and-core approaches. Digital fabrication has advanced both the precision and reproducibility of endocrown manufacture. While computer-aided design/computer-aided manufacturing (CAD/CAM) milled hybrid ceramic endocrowns are well-validated clinically, prospective clinical data comparing 3D-printed definitive restorations to milled counterparts are absent. This trial employs a parallel-group, 1:1 randomized design with triple blinding of participants, outcome assessors, and statistician. All restorations are delivered using Beautilink SA self-adhesive dual-cure resin cement. The primary outcome is fracture resistance at 24 months; secondary outcomes include retention, marginal adaptation, marginal discoloration, surface texture, anatomic form, color match, secondary caries, fabrication time, and patient satisfaction assessed by Visual Analogue Scale (VAS).