Milled vs 3D-Printed Partial-Coverage Restorations in Endodontically Treated Molars

This randomized controlled clinical trial evaluates the clinical performance of indirect composite resin partial-coverage restorations fabricated using subtractive and additive manufacturing technologies in endodontically treated molars.

The study investigates whether 3D-printed composite resin restorations can achieve clinical outcomes comparable to CAD/CAM-milled composite resin restorations when used for cuspal coverage of structurally compromised posterior teeth.

All restorations will be fabricated using a fully digital workflow. Tooth preparation, immediate dentin sealing, digital intraoral scanning, restoration fabrication, and adhesive cementation procedures will be standardized and performed according to a predefined clinical protocol.

The trial will be conducted at Hospital San José, Santiago, Chile, using commercially available restorative materials manufactured by subtractive and additive technologies. Clinical performance will be evaluated according to internationally accepted restorative assessment criteria.

The study aims to generate medium-term clinical evidence regarding the use of 3D-printed composite resin restorations as a potential alternative to conventional CAD/CAM-milled restorations in restorative dentistry.

Inclusion criteria

• Adults aged 18 to 70 years
• Absence of active periodontal disease
• Good oral hygiene (O'Leary plaque index <20%)
• Absence of parafunctional habits (e.g., bruxism, onychophagia)
• Endodontically treated first molars (maxillary or mandibular) with extensive Class II cavities and loss of at least one cusp, requiring onlay or overlay restoration
• Tooth with functional occlusal contact and at least one proximal contact
• Referred from the Endodontics Department of Hospital San José, with endodontic treatment completed at the same institution
• Ability to provide written informed consent
• Ability to attend follow-up visits at 12, 24, and 36 months

Exclusion criteria

• Untreated active periodontal disease
• Poor oral hygiene (O'Leary plaque index ≥20%)
• Generalized active caries
• Active parafunctional habits
• Teeth with complete circumferential structural destruction or insufficient coronal tooth structure for onlay/overlay restoration
• Subgingival margins compromising the biologic width
• Known allergy to study materials
• Pregnancy or breastfeeding