Banca de QUALIFICAÇÃO: FERNANDA GURGEL DE GOIS MOREIRA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : FERNANDA GURGEL DE GOIS MOREIRA
DATE: 29/07/2025
TIME: 08:30
LOCAL: DEPARTAMENTO DE ODONTOLOGIA - SETOR DE PROTÉSE
TITLE:

Mechanical properties, surface topography and clinical performance of 3D printed resins

KEY WORDS:

3D printing; Restorative dentistry; Mechanical strength; Bond strength; Clinical longevity.

PAGES: 139
BIG AREA: Ciências da Saúde
AREA: Odontologia
SUBÁREA: Clínica Odontológica
SUMMARY:

Objective: To investigate, through laboratory, numerical, and clinical analyses, the impact of different variables related to the digital workflow—such as printing parameters, post-processing, finishing and polishing protocols, cementation strategies, and clinical longevity—on the mechanical, adhesive, surface, and clinical properties of 3D-printed materials applied to restorative dentistry. Materials and Methods: In the first phase of the project, 450 resin bars for provisional restorations will be printed using SLA technology (25 × 2 × 2 mm — ISO 4049) and randomly allocated into 30 groups (n = 15) based on the following factors: “layer thickness” (25 μm; 50 μm; 100 μm), “build angle” (0°, 30°, 45°, 60°, 90°), and “thermocycling” (with or without). After printing, the samples will be cleaned with isopropyl alcohol. Photopolymerization will be carried out for 15 minutes using a UV light source. Subsequently, each bar will be measured with a digital caliper at 11 specific points across three dimensions and compared to the STL file to assess dimensional accuracy. Half of the samples will undergo thermocycling. All samples will be subjected to a three-point flexural strength test. In the second phase of the project, 180 bars (25 × 2 × 2 mm — ISO 4049) from each resin type (Provisional/Cosmos Temp, Yller; Occlusal Splint/Cosmos Splint, Yller; Models/CosmosModel, Yller) will be printed and divided into 12 groups (n = 15) according to the following factors: “Post-curing method” (Ctr — control; UV — ultraviolet oven; MW — microwave); “Printer type” (SLA — stereolithography [Form 2/Formlabs]; LCD — liquid crystal display [FlashForge Foto 6.0/FlashForge]); and “Aging” (TC — 10,000 thermocycles or none). Each bar will be measured with a digital caliper at 11 points before and after post-curing to evaluate dimensional stability. In the third phase, 150 bars will be printed (FlashForge Foto 6.0) (25 × 2 × 2 mm) and divided into 10 groups (n = 15), based on layer thickness (25 µm or 50 µm) and finishing and polishing protocols (FP): C — control (no treatment); T — tungsten carbide bur; TG — T + glaze; TP — T + rubber polisher; TPG — T + P + glaze. All specimens will be stored in distilled water at 37 °C for 180 days. Flexural strength tests will be performed (980.6 N; 1 mm/min). Weibull analysis, scanning electron microscopy (SEM), optical profilometry, and microbial adhesion assessment using Candida albicans will be conducted. In the fourth phase, resin blocks (4 × 4 × 4 mm) will be fabricated from three printed materials (PriZma, VarseoSmile Crown Plus, and NanoLab). CAD/CAM blocks (TetricCAD) will be sectioned and standardized to the same dimensions. The samples will be divided according to the following factors: surface treatment (adhesive, airborne particle abrasion with aluminum oxide, surface roughening with diamond bur, and their combinations), silanization (with/without Monobond N), and aging (with/without thermocycling). For stabilization during treatment, the blocks will be positioned in silicone molds. Resin/cement test specimens will be fabricated using silicone molds. The blocks will be partially inserted, receive a layer of light-cured resin cement, followed by filling with composite resin. Subsequently, the assemblies will be sectioned into sticks (1 × 1 × 8 mm) using a precision cutting machine. Half of the specimens will be subjected to 20,000 thermocycles (5 °C–55 °C) and later submitted to microtensile bond strength testing. In the fifth phase, a human mandibular first molar (tooth #36) will be used as a reference for three-dimensional modeling of inlay restorations. The structure will be scanned and digitally modeled using CAD software to generate restorations with different thicknesses, based on the remaining functional cusp height: 3 mm, 2 mm, and 1 mm, resulting in final restoration thicknesses of 4 mm, 5 mm, and 6 mm, respectively. Seven restorative materials will be tested: two 3D-printed resins (Smile Crown and NanoLab), one milled resin (Lava Ultimate), one hybrid ceramic (Enamic), one indirect composite resin, lithium disilicate, and ultra-translucent zirconia. Cementation strategies will include conventional resin cement (RelyX Ultimate) and preheated composite resin. Finite element simulations will be performed using mechanical loading in two directions: vertical and lateral, applied to different occlusal regions such as marginal ridges, fossae, cusp tips, and cusp inclines. Finite element analysis will be performed using ANSYS 19.3 software (ANSYS Inc., Houston, USA), with a refined mesh in regions of interest and boundary conditions simulating the oral environment. Tensile, compressive, and shear stresses, as well as fracture resistance, crack initiation and propagation patterns, and shear bond strength between the restoration and the dental substrate will be evaluated. In the sixth phase, a simplified digital workflow for a full-arch implant-supported prosthesis will be described, including vertical dimension of occlusion (VDO) rehabilitation, using a 3D-printed provisional prosthesis and an esthetic guide for maxillary incisors. After defining the VDO and performing the intraoral scan, a screw-retained provisional prosthesis will be printed, clinically tested, and used to guide the fabrication of the definitive restoration. Finally, in the seventh and final phase, 50 crowns will be fabricated and included in this study. All participants will sign the informed consent form. The teeth undergoing temporary rehabilitation will be randomly allocated into two groups: Control Group (CG — milled resin) and Experimental Group (3D — printed resin). Photographic, radiographic, and clinical data will be collected before, during, and after rehabilitation. The crowns will be evaluated based on clinical survival rate (modified USPSH criteria), esthetic satisfaction (visual analog scale — VAS), quality of life (Oral Impacts on Daily Performances — OIDP), and failure types (biological and technical). Data collection will be conducted by a single calibrated examiner, blinded to the material, at the following time points: T0 (baseline), T1 (7 days post-cementation), T2 (15 days post-cementation of the posterior provisional crown), T3 (30 days), and T4 (45 days post-cementation of the temporary crown). Future Perspectives: Considering the scientific progress in 3D-printed restorations and their expanding clinical indications, this study aims to contribute to the consolidation of evidence regarding the feasibility and performance of these materials, both in laboratory settings and in clinical practice.

COMMITTEE MEMBERS:
Presidente - 1640419 - RODRIGO OTHAVIO DE ASSUNCAO E SOUZA
Externa ao Programa - 2492886 - SAMIRA ALBUQUERQUE DE SOUSA - UFRNExterna à Instituição - NATHALIA RAMOS DA SILVA - ABO