FULL CROWN RESTORATION OBTAINED BY EXPERIMENTAL 3D PRINTING RESIN: INTERNAL FIT, MECHANICAL AND PHYSICAL PERFORMANCE POST-CEMENTATION

• Grant number: 25/06444-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: July 01, 2025
• End date: June 30, 2026
• Field of knowledge: Health Sciences - Dentistry - Dental Clinics
• Principal Investigator: Ester Alves Ferreira Bordini Galvani
• Grantee: Nicoly Gabriely Gonçalves
• Host Institution: Faculdade de Odontologia de Ribeirão Preto (FORP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

Introduction. Additive manufacturing through 3D printing has gained focus as an efficient and innovative alternative for the fabrication of dental crowns, offering advantages such as cost reduction, decreased material waste, faster production processes, and improved anatomical accuracy. Despite these advantages, key challenges persist, especially with regard to color stability, mechanical strength, and the marginal and internal fit of restorations, factors that play a vital role in the long-term clinical performance of these treatments. Aim. In this context, the present study aims to evaluate the influence of incorporating zinc oxide (ZnO) nanoparticles into a photopolymerizable resin used in 3D printing, focusing on the physicochemical and mechanical characterization of full crown restoration. This research seeks to determine whether ZnO-enhanced resins improve mechanical resistance, color stability, and marginal/internal adaptation, thereby advancing the clinical application of these materials in digital restorative dentistry. Materials and Methods. A lower molar will be prepared following standardized clinical parameters and subsequently scanned using a digital scanner. Full-coverage crowns will be designed using CAD software and fabricated by milling in PMMA (control group) and by 3D printing with both unmodified resin and resin modified with ZnO nanoparticles (experimental) at concentrations of 0.5% and 1.0% (w/v), combined with a polymeric dispersant. Printing will be performed at angles of 0°, 45°, and 90° using the m-SLA Phrozen Sonic 4K printer, followed by cementation with Panavia V5 resin cement. The specimens will undergo thermomechanical aging and will then be evaluated for marginal adaptation (stereomicroscopy), internal adaptation (stereomicroscopy), degree of conversion (FTIR-ATR), compressive strength (mechanical testing machine), and color stability (VITA Easyshade V). Fracture patterns will also be analyzed. Justification. The search for restorative materials that combine strength, dimensional stability, esthetics, and cost-effectiveness is closely aligned with the evolution of digital workflows and current social demands. The incorporation of ZnO may not only provides mechanical reinforcement to the resin but may also enhance adhesion, crown adaptation, and optical stability, key factors for the clinical longevity of indirect restorations. The clinical application of 3D printers becomes even more promising when combined with innovative formulations that offer high performance, affordability, and ease of use. Thus, this study aims not only to understand the impact of resin modification but also to provide scientific and technical support for the integration of such solutions into daily dental practice. Expected Results. It is expected that the addition of ZnO nanoparticles to 3D printing resins will result in significant improvements in compressive strength, color stability, and marginal and internal fit of the crowns compared to the control group. These findings may broaden the clinical applicability of printed resins, offering dental professionals a more accessible, efficient, durable, and esthetic restorative alternative, with potential use in both long-term provisional and definitive crowns. (AU)