Análise comparativa in vitro da radiopacidade e da rugosidade superficial de resinas compostas bulk fill e monocromáticas após escovação simulada

Abstract

In recent years, bulk fill and monochromatic composite resins have gained prominence for introducing promising innovations in dental practice. The study of their properties reflects the ongoing effort to improve and simplify their clinical handling. To ensure the success of restorations and patient satisfaction, it is essential to make a judicious material selection, focusing on properties such as radiopacity and surface roughness, which are critical for evidence-based clinical decisions by dental professionals. This in vitro study aimed to evaluate the radiopacity and surface roughness of bulk fill and monochromatic composite resins compared to a conventional composite resin. Four composite resins were tested (two bulk fill: Filtek One Bulk Fill and Tetric N-Ceram Bulk Fill; and two monochromatic: Vittra APS Unique and Palfique Omnichroma), and these were compared to the conventional Filtek Z350 XT resin (control). Ten specimens (5 mm in diameter and 2 mm in thickness) were fabricated for each resin. Surface roughness was assessed using a 3D Optical Profilometer (Talysurf CCI MP, Leicester, UK), and radiopacity was evaluated using an intraoral radiography device, FOCUS 50540-IMG (Kavo, Potsdam, Germany), at three exposure times (0.20s, 0.32s, and 0.4s). The grayscale of the digital images was analyzed using the ImageJ software. After initial measurements (T0), the samples underwent 50,000 cycles of simulated toothbrushing, equivalent to four years of clinical use, and the measurements were repeated (T1). Statistical analysis involved descriptive and non-parametric tests due to the non-normal distribution of the data, as determined by the Shapiro-Wilk test. A significance level of 5%, a 95% confidence interval, and an 80% statistical power were adopted, using SPSS 20.0 software. At T0, significant differences were observed among the resins (p < 0.05), with monochromatic resins showing lower surface roughness. All resins, except Tetric N-Ceram Bulk Fill (p>0.05), exhibited a significant increase in roughness after simulated brushing (p<0.05). However, all groups showed similar surface roughness values at T1 (p>0.05). Regarding radiopacity, at T0, the resins demonstrated higher radiopacity at the shortest exposure time (0.2s), with significant differences between times and resins (p<0.001). The Tetric N Ceram Bulk Fill stood out for having the highest radiopacity, while the Palfique Omnichroma exhibited the lowest values across the three exposure times evaluated. At T1, no significant differences were observed regardless of time and material (p>0.05). It was concluded that monochromatic resins were initially smoother; however, after simulated brushing, all resins showed an increase in roughness, except for Tetric N-Ceram Bulk Fill. The initial analysis revealed that the radiopacity of the resins was higher at the 0.2s radiographic exposure time, influenced by the exposure times and type of material. After simulated brushing, all resins exhibited similar roughness and radiopacity, with initial differences diminished by abrasive wear.