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Introduction: Post-processing (PP) is performed to improve the surface, which can favor microbial adhesion and consequent pathological manifestations that impair the indication of polylactic acid (PLA) obtained by fused filament fabrication (FFF) for biomedical applications. This aims to evaluate the influence of chemical, thermal, and mechanical PP on the adhesion of Streptococcus mutants and Candida albicans, roughness, and wettability of the PLA obtained by FFF with and without thermal aging. Methods: The specimens were designed in the 3D modeling program and printed. The chemical PP was performed by immersion in chloroform, the thermal by the annealing method, and the mechanical by polishing. Thermal aging was performed by alternating the temperature from 5 °C to 55 °C with 5000 cycles. Colony-forming unit (CFU/mL) counting was performed on dual-species biofilm of C. albicans and S. mutans. Roughness was analyzed by rugosimeter and wettability by the sessile drop technique. Data were verified for normality using the Shapiro-Wilk test, two-way ANOVA (α = 0.05) applied for CFU and wettability, and Kruskal-Wallis (α = 0.05) for roughness. Results: Chemical, thermal, and mechanical PP methods showed no influence on CFU/mL of C. albicans (p = 0.296) and S. mutans (p = 0.055). Thermal aging did not influence microbial adhesion. Chemical PP had lower roughness, which had increased after aging. Wettability of the mechanical PP was lower. Conclusions: Post-processing techniques, do not present an influence on the adhesion of S. mutans and C. albicans in PLA obtained by FFF, chemical PP reduced roughness, and mechanical reduced wettability. Thermal aging did not alter the microbial adhesion and altered the roughness and wettability.
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STATEMENT OF PROBLEM: Digital methods for manufacturing occlusal devices provide advantages over conventional techniques, but information about the mechanical properties of 3-dimensionally (3D) printed resins is scarce. PURPOSE: The purpose of this systematic review was to evaluate the literature to determine whether 3D-printed resins for occlusal devices present satisfactory mechanical performance when compared with milled and conventional heat polymerized and autopolymerized resins. MATERIAL AND METHODS: This systematic review followed the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol and was registered in the Open Science Framework. The search strategy was applied without restriction of time and language to Embase, PubMed, Scopus, Science Direct, and Web of Science databases, and to the nonpeer-reviewed literature in ProQuest and Google Scholar. The selection process was conducted independently in 2 stages by 2 reviewers according to the eligibility criteria. The risk of bias was analyzed by using a checklist of important parameters to be considered. The systematic review considered the population, intervention, comparison, outcome, studies (PICOS) format, where population was resins for 3D printing of occlusal devices, intervention was inherent characteristics of the resin, comparison was conventional heat polymerized, autopolymerized, and milled resins, outcome was mechanical performance, and studies were in vitro experimental studies. RESULTS: A total of 1430 articles were found with the search strategy. After removing 182 duplicates found in Rayyan, the title and abstract of 1248 articles were evaluated, of which 37 articles were screened from the databases, 23 were selected for full reading, and 6 met the eligibility criteria and were included in this review; 1 had a low risk of bias and 5 had a moderate risk. An additional search of the reference list of included articles did not result in the inclusion of any articles. A quantitative meta-analysis could not be performed because of the heterogeneity of the included studies regarding the type of resin used and the method for evaluating mechanical performance. CONCLUSIONS: Resins for 3D printing had satisfactory mechanical performance for interocclusal devices when compared with conventional heat polymerized and autopolymerized resins, except for hardness. Milled resins were better than 3D-printed resins in hardness, wear resistance, flexural strength, flexural modulus, and fracture resistance when printing angle and thickness were not considered. Further development is needed in terms of printing techniques and chemical composition, as they are important for optimal mechanical properties and clinical performance.
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Aim: The objective of this systematic review is to show the current state of the art on which type of attachment loses retention the most and has reduced durability and which factor causes these problems the most. Material and methods: This review followed the Preferred Reporting Items for Systematic Review and MetaAnalysis (PRISMA) guidelines and it was registered with the Open Science Framework (OSF) (osf.io/2e3q5). The databases used for the electronic search of articles were Pubmed, Science Direct, Embase, and Scopus. Articles were selected by 2 independent reviewers according to the inclusion criteria. The risk of bias was analyzed by using the Joanna Briggs Institute (JBI) adapted quasi-experimental study evaluation tool. Results: The studies included in this review indicate that the use of cleansing solutions, high temperatures, and a more acidic pH decrease the durability of the attachments, mainly due to the loss of retention that occurs in different models and materials of the attachments, which requires their replacement in a shorter period. Conclusion: Of all the factors studied, the cleansing solutions proved to be the factor that most altered attachment retention. Different saliva compositions did not influence retention values. Aging changes retention values for attachments, mostly with loss of values.
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OBJECTIVE: To establish parameters for standardized assessment of the moldability of thermoplastic materials used in orthotic manufacturing and to develop tests for quantification of moldability parameters by simulating the demands of clinical practice, in order to enable accurate and controlled analysis of material properties. PRIMARY OUTCOME MEASUREMENTS: Two commercially available materials were submitted to tests for standardized measurement of moldability. Results were correlated with manufacturer information. Moldability assessment was based on two parameters (conformation and fit), expressed as percentages. RESULTS: Tests, standardized molding procedures and measurements were described. Quantitative data (conformation and fit expressed in percentages) were derived from a pilot study comparing Aquaplast-T™ and Ezeform™. Findings of that study revealed that Aquaplast-T™ is more moldable than Ezeform™ and support technical information provided by the manufacturer. CONCLUSIONS: The assessment method described enabled objective and repeatable measurement of the moldability of materials used in orthotic manufacturing and represent a significant advancement in comparative analysis of materials, with potential positive impacts on therapeutic procedures and clinical decision-making. Tests developed in this study can be used to quantify data provided by manufacturers in order to allow their use by researchers and professionals in rehabilitation.
