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

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).

Inclusion criteria

• Age 25-45 years, male or female
• Endodontically treated molar tooth with radiographically confirmed treatment success and no clinical signs of failure
• Sufficient remaining coronal structure for endocrown preparation: minimum three walls, wall thickness 1.5 mm or greater, pulp chamber depth 3 mm or greater, supragingival preparation margins
• Completely erupted tooth with intact periodontal support
• Minimum of 20 occluding teeth
• Satisfactory oral hygiene status
• Capable of providing written informed consent and committed to scheduled follow-up visits

Exclusion criteria

• Diagnosed parafunctional habit or nocturnal bruxism
• Uncontrolled systemic illness or physical disability precluding safe participation
• Heavy tobacco use
• Current or suspected pregnancy
• Periapical disease or radiographic signs of endodontic failure
• Evidence of pathological tooth wear or occlusal erosion
• Moderate-to-severe periodontitis or tooth with hopeless prognosis
• Radiographic or clinical evidence of vertical root fracture
• Impaired decision-making capacity or anticipated non-compliance