Banca de QUALIFICAÇÃO: JOÃO VITOR DO NASCIMENTO SANTOS

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : JOÃO VITOR DO NASCIMENTO SANTOS
DATE: 18/11/2025
TIME: 16:30
LOCAL: Departamento de Odontologia - VIRTUAL MEET
TITLE:

Interfacial optimization strategies for additively manufactured zirconia: effects of glass infiltration and surface treatments on adhesion, structural performance, and mechanical integrity.

KEY WORDS:

Dental prosthesis; Zirconia; Additive manufacturing; Surface modification; Bond strength; Structural performance.

PAGES: 56
BIG AREA: Ciências da Saúde
AREA: Odontologia
SUMMARY:

The adhesion between zirconia ceramics and resin cements remains one of the main challenges in restorative dentistry, especially with the advent of zirconias produced by additive manufacturing. These new ceramics exhibit heterogeneous microstructures, mechanical anisotropy, and distinct surface energy, factors that may affect their adhesive behavior and structural performance. In this context, the present study aims to understand and optimize the adhesive interface and structural performance of 3D-printed zirconia by investigating the influence of glass infiltration techniques, surface treatments, and fabrication methods. A laboratory-based experimental study will be conducted in three stages. Stage I will analyze the effects of surface treatments and Immediate Dentin Sealing (IDS) on the bond strength between 3D-printed and milled zirconia to human dentin. A total of 360 zirconia cylinders (LithaCon 3Y 230, printed at 0°, 45°, and 90°, and NexxZr+ Multi, milled) will receive different surface treatments: Ctrl – primer only; Al – airborne-particle abrasion with 50 µm Al₂O₃ + primer; and Si – tribochemical silicatization + primer. The cylinders will be luted with dual-cure resin cement to dentin from human molars embedded in acrylic resin blocks. All groups will undergo artificial aging through thermocycling (10,000 cycles). Shear bond strength (SBS) tests and fractographic analysis will be performed using optical stereomicroscopy (40×) and scanning electron microscopy (SEM). Surface characterization will include SEM imaging, microhardness, and wettability testing. Stage II will evaluate the effects of glass infiltration strategies and acid conditioning on the bond strength of printed and milled zirconia to resin cement. A total of 160 ceramic blocks (3D-printed zirconia – LithaCon 3Y 230, milled zirconia – NexxZr+ Multi, and lithium disilicate – e.max CAD) will be divided according to the infiltration strategy: Ctrl (disilicate) – etching with 10% hydrofluoric acid (HF) for 20 s + silane; BG – borosilicate glass application + 10% HF for 90 s + silane; Li1 – one application of Lisi Connect + 10% HF for 90 s + silane; and Li2 – two applications of Lisi Connect + 10% HF for 90 s + silane. Surface roughness will be analyzed using optical profilometry, followed by luting of dual-cure resin cement cylinders. Half of the specimens will undergo thermocycling (10,000 cycles), and the others will be stored in distilled water at 37 °C for 24 h. SBS testing and fractographic evaluation (stereomicroscope and SEM) will be performed, while Energy Dispersive X-ray Spectroscopy (EDS) will assess surface chemical composition. Stage III will examine the geometric accuracy, marginal and internal discrepancies, and compressive strength of monolithic zirconia crowns produced using different fabrication methods and glass infiltration protocols. First, a lower molar model will be prepared and scanned using an extraoral scanner (DSEX Shining 3D). Then, a monolithic zirconia crown will be designed using CAD software (Dental Wings). Ten crowns will be 3D printed from the STL file (LithaCon 3Y 230), ten will be milled (NexxZr+ Multi), and ten lithium disilicate crowns (e.max CAD) will serve as controls. After sintering and scanning, the clinical accuracy, including marginal and internal adaptation and interproximal contacts, will be digitally evaluated, and the marginal quality will be examined under optical microscopy. Data from all stages will be statistically analyzed using ANOVA, Tukey’s post hoc test (α = 0.05), and Weibull analysis. Expected outcomes include the identification of innovative surface and glass infiltration protocols capable of improving the adhesion, accuracy, and mechanical performance of 3D-printed zirconia, contributing to the advancement of additive manufacturing in restorative dentistry and its safe, predictable clinical application.

COMMITTEE MEMBERS:
Presidente - 1640419 - RODRIGO OTHAVIO DE ASSUNCAO E SOUZA
Interno - 1031499 - LAERCIO ALMEIDA DE MELO
Externa à Instituição - NATHALIA RAMOS DA SILVA - ABO