Functional gradation with experimental glass in implant-based zirconia crowns: wear, colour stability, immune response in a randomized clinical and translational trial

• Grant number: 23/00580-9
• Support Opportunities: Regular Research Grants
• Start date: October 01, 2023
• End date: September 30, 2024
• Field of knowledge: Health Sciences - Dentistry - Dental Clinics
• Principal Investigator: Renata Marques de Melo Marinho
• Grantee: Renata Marques de Melo Marinho
• Host Institution: Instituto de Ciência e Tecnologia (ICT). Universidade Estadual Paulista (UNESP). Campus de São José dos Campos. São José dos Campos , SP, Brazil
• Associated researchers: Ana Paula Vieira Colombo ; Carina Maciel da Silva Boghossian ; Marcos Fabio Henriques dos Santos

Abstract

Glass infiltration in zirconia emerged with the aim of making it even more resistant and starting a path for indirect restorations without the need for porcelain layering. This functionally graded material, with smooth property transitions and a glass surface layer, prevents delamination and fracture, reduces wear on the opposing tooth and increases flexural strength. Furthermore, it is possible to include antimicrobial agents in the glass powder composition. This addition can be highly advantageous, since biological complications such as caries, periodontitis or peri-implantitis are described in clinical studies with ceramic prostheses. In vitro studies of glass development, to verify its application in zirconia, both from aesthetic and mechanical aspects, have already been carried out. Thus, in this study, the use of experimental glass infiltration technology will be tested in ceramic restorations on implants. The objective of the present study will be to evaluate how the glass grading process through the application of this glass (experimental glaze) in implant-supported crowns of ultra-translucent zirconia (5Y-PSZ) influences the clinical prognosis, when compared to implant-supported crowns with commercial glaze. 90 patients will be selected through pre-established exclusion and inclusion criteria, and after signing the free and informed consent form, they will undergo surgery to install Cone Morse Strong SW Plus (S.I.N. Implant System) implants. After a period of osseointegration (2-4 months) crowns will be made on implants screwed in zirconia through digital flow. In total, 90 implants will be installed and divided into two groups: Group with ultra-translucent zirconia crown and commercial glaze (GC) and another group with ultra-translucent zirconia and experimental glaze (VI). The parameters will be evaluated through analysis of color stability by VITA Easyshade® Compact, wear by ExoCad Dental Software (Align Technology), immunological analysis at 6 months, 1 year and 1 year and 6 months and peri-implant evaluations and subgengival biofilm evaluation. The data will be submitted to exploratory analysis and subsequently analyzed in an inferential way with the most appropriate test (p<0.05). Qualitative data will be analyzed using images. Crowns on ultratranslucent zirconia implants with experimental glaze are expected to cause less wear on the antagonist tooth due to the presence of the superficial glass layer, without changing the color in the long term. The presence of glass between the zirconia grains will possibly favor the mechanical behavior of ultra-translucent zirconia, reducing the presence of cracks and possible catastrophic failures of the material by waiting for the infiltration glass to compensate for the drop in resistance inherent to ultra-translucent zirconia, improving their clinical prognosis. Regarding immunological analyses, it is presumed that this experimental glaze has a better integration into the peri-implant tissues due to its promising cell viability results observed in previous in vitro tests. (AU)