A comparative study of two polishing systems on the surface roughness of acrylic resins for temporary restorations at Pedro Henríquez Ureña National University. In vitro study.
Description
In dental practice, temporary restorations made with self-curing acrylic resins are commonly used to protect prepared tooth structures, maintain function and aesthetics, and promote the health of oral tissues until the final prosthesis is placed. The surface quality of these restorations determines their clinical success because a smooth surface reduces biofilm accumulation, pigmentation, and the risk of caries and periodontal disease. Additionally, a smooth surface improves aesthetics and biocompatibility. According to the literature, a surface roughness of less than 0.2 µm minimizes these risks. This study compared the effectiveness of two polishing systems (Kit 1 and Kit 2) on the surface roughness of acrylic resins for temporary restorations used at the Dr. René Puig Bentz dental clinic at Pedro Henríquez Ureña National University from September to December 2025. The goal was to identify the system that provides the most suitable surface finish for clinical application. The methodology consisted of preparing self-curing acrylic resin samples that were mechanically polished according to the protocols of each system. We evaluated surface roughness using a roughness tester, which measures microscopic irregularities by scanning the surface with a fine tip and converting the variations into quantifiable values for comparative analysis. The results revealed statistically significant differences between the two polishing systems. Kit 2 produced higher average surface roughness values than Kit 1 (mean: 1.416 µm vs. 1.109 µm; median: 1.373 µm vs. 1.014 µm), suggesting that Kit 2 generates relatively rougher surfaces. Likewise, measures of central tendency, including the mode, were consistently higher in Kit 2, confirming a less smooth surface finish. In terms of data dispersion, Kit 2 showed slightly higher standard deviations, suggesting greater variability in the results. This variability may be related to differences in the abrasive design, cutting pattern, and stability during polishing. Kit 1 had a lower maximum value, indicating a more uniform finish without extreme values affecting surface homogeneity. However, neither system achieved values of 0.2 µm or less, with both falling above the clinically acceptable threshold for optimal permanence in the oral cavity. In conclusion, the polishing system in Kit 1 was more effective than Kit 2 at reducing the surface roughness of acrylic resins for temporary restorations. However, neither system achieved the recommended optimal level. These findings confirm the alternative hypothesis (H1) and underscore the necessity of optimizing polishing protocols in academic training and clinical practice due to surface roughness's direct influence on the aesthetics, biocompatibility, and clinical success of temporary restorations.
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Steps to reproduce
Fifty self-curing acrylic resin discs were prepared according to the proportions recommended by the manufacturer of the acrylic resin, using a test body provided by the CIBO-UNIBE laboratory. This complied with the proportions recommended by the manufacturer of the roughness tester. Once the samples were made, the 50 discs were classified into two groups according to the polishing system brand: kit 1 and kit 2. Twenty-five discs were polished by the Kit 1 group, and the remaining twenty-five were polished by the Kit 2 group. They were identified and numbered. The samples were polished by the same operator using an electric micromotor, the Kit 1 and Kit 2 polishing systems, and the sequence and revolutions indicated by the manufacturer for each type of bur. All the manufacturers' specific protocols for the two analyzed polishing systems were followed to ensure methodological fidelity and reproducibility of the procedure. After the pilot test was completed and approved by the Research Department, data collection began in the prosthetics area of the Dr. René Puig Bentz Dental Clinic and the CIBO Laboratory at Unibe. After polishing the samples according to protocol, an appointment was made at the CIBO-UNIBE laboratory to process the 50 samples using the Time TR210 roughness tester. To properly organize the information, a form was designed (see Annex 4) to record the number of samples analyzed for each material, ensuring systematic control of the results. This form served as a database that allowed for detailed tracking of the measurements taken. For this phase, 50 samples that strictly met the previously established inclusion and exclusion criteria were selected. The CIBO-UNIBE laboratory provided the test body, which complies with the roughness tester's measurement parameters. The samples were polished according to the aforementioned protocols. The samples were then processed in the CIBO-UNIBE laboratory using the TIME TR210 roughness tester. Three measurements were taken from each sample in different areas to calculate its average surface roughness. Finally, the thesis advisors processed and reviewed all the results, and then collaborated with a statistician to produce tables and average results.
Institutions
- Universidad Nacional Pedro Henríquez UreñaNacional, Santo Domingo