Effect of acid erosion on the structural and optical properties of long-term 3D resin printedd crowns. An in situ study.

• Grant number: 25/05765-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: June 01, 2025
• End date: May 31, 2026
• Field of knowledge: Health Sciences - Dentistry - Dental Materials
• Principal Investigator: Jéssica Marcela de Luna Gomes
• Grantee: Rebeca Baroneza Fantin
• Host Institution: Faculdade de Odontologia (FOA). Universidade Estadual Paulista (UNESP). Campus de Araçatuba. Araçatuba , SP, Brazil

Abstract

3D printed resins for long-term restorations combine the organic material characteristics of composite resins associated with the glass matrix of ceramics in their composition with the aim of improving their properties. They are indicated for rehabilitation of indirect restorations, such as single crowns. In addition, there is currently an increase in the prevalence of dental erosion in the population, therefore, prosthetic rehabilitation in these cases is challenging since the restorative materials also undergo erosion with exposure to acids. Given the scarcity in the literature regarding the longevity of these restorations regarding optical and surface properties and the in situ methodology to elucidate results closer to clinical use, the objective of this study is to evaluate the influence of in situ acid erosion on the structural and optical properties of printed resins for restoration: Prisma 3D Bio Crown (Makertech Labs, Tatuí, São Paulo) and VoxelPrint (FGM Dental Group, Joinville, SC), through the analysis of surface roughness (LSM), Knoop microhardness (MK) and color change (¿E00, ¿L, ¿C, ¿H), contrast (CR) and translucency (TP). This study will be submitted to the CEP (Human Research Ethics Committee) of the Araçatuba School of Dentistry - FOA/UNESP. For this purpose, 60 specimens will be produced and divided into two groups (n = 30) according to the type of printed resin and before and after the in situ experiment (with and without acid erosion). The specimens will be designed and exported for printing on the Anycubic 4k printer and cured on the Anycubic M2. The prints will be made at 90¿ for the platform with a layer thickness of 100µm, measuring 2×2×25 mm. After printing, all samples will be cleaned with a cloth soaked in ethanol (>90%) and dried with air jets, following the manufacturer's recommendation. Fifteen (15) volunteers of both sexes, aged between 18 and 30 years old and in good general and oral health and with normal salivary flow, will be selected for the in situ study. Each volunteer will use an intraoral device containing four specimens, which will be exposed to acid erosion. Acid erosion consisted of immersing the specimens in 150 ml of freshly opened cola-based soft drink (Coca-Cola, pH = 2.3) for 5 min, 4 times a day for 14 consecutive days. The analyses will be performed after printing and curing (T1) and after in situ experiment (T2) for the analyses of surface roughness (LSM), Knoop microhardness (MK), and color change (¿E00, ¿L, ¿C, ¿H), contrast (CR) and translucency (TP). After the results, the data from the measurements for each type of analysis will be organized in an Excel table and submitted to SigmaPlot software version 13.0 and analyzed in relation to the normal distribution (Shapiro-Wilk test and equality of variance) and, subsequently, the data will be submitted to the most pertinent statistical analysis as indicated by the results. (AU)