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Purpose: To analyze the effect of disinfectants on the roughness and mechanical properties of CAD/CAM polymethylmethacrylate (PMMA) dentures. Materials and Methods: Two groups of denture base resins were tested--heat-polymerized and milled blocks. For each resin, 120 specimens were produced for flexural strength (FS) and flexural modulus (FM) analyses (total: 240 specimens), and 40 were produced for microhardness and surface roughness evaluations (total: 80 specimens). They were categorized into the following groups based on immersion: control (deionized water); H1 (1% sodium hypochlorite); H05 (0.5% sodium hypochlorite); and C2 (2% chlorhexidine) groups. The immersion periods were 0 (T0), 130 (T1), and 260 (T2) cycles. Statistical analyses were performed for flexural properties using threeway ANOVA. Microhardness (KHN) and surface roughness (Ra) were analyzed using repeated-measures ANOVA. A significance level of 5% was set. Results: CAD/CAM PMMA showed higher FS (P = .001) and FM (P < .001) than conventional PMMA. The KHN value was superior to the conventional PMMA (P < .001). The chemical solution affected the surface roughness of both resins (P = .007). The CAD/CAM PMMA block showed increased Ra values when H1 was used. Cycling separately increased the FS of conventional PMMA (T1 vs baseline; P < .05). However, the FM of CAD/CAM PMMA was higher (T1 and T2 vs baseline; P < .05). The time factor increased the microhardness of both resins (T2 vs baseline; P < .05). Conclusions: The CAD/CAM resin showed higher values compared to conventional PMMA in all tests, regardless of the chemical solution used; however, the values obtained for both resins were clinically acceptable. [ABSTRACT FROM AUTHOR]

Objective: To systematically evaluate the effect of microwave disinfection on the dimensional stability of denture base acrylic resins. Background: Microwave disinfection has been considered as an alternative method for disinfecting complete dentures to help prevent and treat denture stomatitis. However, data on the impact of microwave disinfection on the dimensional stability of acrylic resins are still scarce. Methods: The PubMed/Medline, SCOPUS and EMBASE databases were searched in order to assess articles published in English up to January 2021 (CRD42021212267). We included studies that have assessed the effect of microwave disinfection, on the dimensional stability of acrylic resins, comparing them with negative or positive controls. Results: A total of seven in vitro studies were included. The qualitative synthesis demonstrated that, in general, microwave disinfection produced more distortion on the materials than do immersion in sodium hypochlorite, chloride solution, chlorhexidine, and water immersion. However, considering the dimensional stability of the specimens, microwave disinfection at 500 W for 3 minutes, and at 450 W for 5 minutes, produced similar or better outcomes than did control groups. Conclusion: In general, microwave disinfection promotes changes in the dimensional stability of denture base acrylic resins, and should thus be used with caution. However, microwave disinfection protocols at lower power settings (500 and 450 W) and exposure times (3 and 5 minutes) produces similar or less distortion than chemical disinfection. More studies are still required in order to evaluate the clinical and long‐term implications of microwave disinfection. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the clinical performance of three preventive materials on the occlusal surfaces of primary molars over a 36-month period. Material and Methods: The study was conducted with a split-mouth design involving four experimental groups: G1 - resin-modified glass ionomer cement (Vitremer®); G2 - resin sealant (Alpha Seal Light®); G3 - silver diamine fluoride (Cariostatic®); and G4 - control group without material. Thirty-two children aged 36 to 60 months, attending a pediatric clinic, with a deft index = 1 and four primary second molars participated in the study. The material retention was evaluated in G1 and G2, and the presence of incipient caries was evaluated in all groups. Data were submitted to the Wilcoxon test and survival test (α = 5%). Results: At three, six, 12, 24 and 36 months, G2 exhibited greater material loss (maximum loss: 44%) in comparison to G1 (maximum loss: 35%), but this difference did not achieve statistical significance (p = 0.214). The highest incidence of incipient caries occurred in G3 (20%), but no significant differences were found between groups at any evaluation time (p = 0.154). Conclusion: There were no statistically significant differences between the evaluated products regarding material retention and dental caries, although there was more material loss in teeth that received the Alpha Seal® sealant resin, and a greater number of carious lesions in the Cariostatic® group (silver diamine fluoride). [ABSTRACT FROM AUTHOR]

The characteristics of the denture base surface, in combination with the oral environment, promote the colonization and development of Candida albicans biofilm, which is the main cause of denture stomatitis. This study evaluated the effectiveness of fibrin biopolymer with digluconate chlorhexidine or Punica granatum alcoholic extract to prevent C. albicans biofilm. Conventional heat polymerized and pre-polymerized poly(methyl methacrylate) (PMMA) circular specimens (10 × 2 mm) were fabricated (n = 504) and randomly divided into groups: no treatment (control—CT), fibrin biopolymer coating (FB), fibrin biopolymer with P. granatum (FBPg), or digluconate of chlorhexidine (FBCh) coating. The specimens were inoculated with C. albicans SC5314 (1 × 107 cells/mL) and incubated for 24, 48, and 72 h. Crystal violet and colony-forming unit assays were used to quantify the total biofilm biomass and biofilm-living cells. A qualitative analysis was performed using confocal laser scanning microscopy. Data obtained are expressed as means and standard deviations and were statistically analyzed using a three-way analysis of variance (α = 0.05). The FBPg and FBCh groups inhibited the growth of C. albicans biofilm in both PMMA materials analyzed, with FBCh performing better in all periods evaluated (p < 0.0001). The colony forming unit (CFU) assay showed that the FB group favored the C. albicans biofilm growth at 24 h and 48 h (p < 0.0001), with no differences with CT group at 72 h (p = 0.790). All groups showed an enhancement in biofilm development up to 72 h (p < 0.0001), except the FBCh group (p = 0.100). No statistical differences were found between the PMMA base materials (p > 0.050), except in the FB group (p < 0.0001). Fibrin biopolymer, albeit a scaffold for the growth of C. albicans, when combined with chlorhexidine digluconate or P. granatum, demonstrated excellent performance as a drug delivery system, preventing and controlling the formation of denture biofilm. [ABSTRACT FROM AUTHOR]

Currently, there is no consensus on the indications and clinical performance of implant-supported overdentures (IODs) involving computer-aided design and manufacturing (CAD-CAM) bars., Objective: To evaluate the performance of IODs involving CAD-CAM bars., Methodology: A comprehensive search of studies published until May 2023 was conducted in many databases, including PubMed/MEDLINE, Web of Science, Cochrane Library, and SciELO, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The population, intervention, comparison, outcome (PICO) question was: "How do IODs retained by bars fabricated by CAD-CAM technology perform in daily clinical practice?" The meta-analysis included clinical studies based on effect size and a two-tailed null test with a 95% confidence interval (CI)., Results: Ten studies were included in the meta-analysis. Among them, nine reported a 100% implant survival rate for all CAD-CAM milled bars. Complications were reported in two studies with CAD/CAM-milled titanium bars, and one study reported more fractures in soldered gold bars used in maxillary rehabilitation. However, no fractures were observed in IODs retained by PEEK and zirconia bars. According to six studies, biological complications, including peri-implantitis, were minimal in the BioHPP and PEEK bar groups, while no cases were reported in the titanium or zirconia bar groups. CAD-CAM-milled zirconia bars had higher plaque and bleeding indices compared with titanium bars, as evidenced by findings from five studies. All four studies that evaluated Oral Health Impact Profile (OHIP) scores showed a positive effect of IODs retained by CAD-CAM milled titanium bars on quality of life. Patient satisfaction and acceptance by prosthodontists were significantly high, according to the results of five studies., Conclusion: Overdentures retained with CAD-CAM milled titanium bars show great potential for use in daily clinical practice. Moreover, patient and practitioner satisfaction was very high when this method was used.

Purpose: This study was aimed at analyzing the effect of disinfectants on the roughness and mechanical properties of computer-aided design/computer-aided manufacturing (CAD/CAM) polymethylmethacrylate (PMMA) dentures., Materials and Methods: Two groups of denture base resins were tested: heat-polymerized and milled blocks. The specimens were shaped (n=80) for flexural strength (FS), flexural modulus (FM), and (n=240) for the properties of roughness (Ra) and microhardness alterations (KHN). They were categorized into the following groups based on immersion: control (deionized water), H1 (1% sodium hypochlorite), H05 (0.5% sodium hypochlorite), and C2 (2% chlorhexidine) groups. The immersion periods were 0 (T0), 130 (T1), and 260 (T2) cycles. Statistical analyses were performed for flexural properties using the three-way analysis of variance (ANOVA). Microhardness and surface roughness were analyzed using repeatedmeasures ANOVA. A significance level of 5% was set., Results: CAD/CAM PMMA showed higher FS ( P = .001) and FM ( P < .001) than conventional PMMA. The KHN value was superior to the conventional PMMA ( P < .001). The chemical solution affected the surface roughness of both resins (P = .007). The CAD/CAM PMMA block showed increased Ra values when H1 was used. Cycling separately increased the FS of conventional PMMA (T1 vs. baseline; P < .05). However, the FM of CAD/CAM PMMA was higher (T1 and T2 vs. baseline; P < .05). The time factor increased the microhardness of both resins (T2 vs. baseline; P < .05)., Conclusion: The CAD/CAM resin showed higher values compared to conventional PMMA in all tests, regardless of the chemical solution used; however, the values obtained for both resins were clinically acceptable. Int J Prosthodont 2023. doi: 10.11607/ijp.8301.

Aim: The aim of this study was to evaluate the stress distribution of a planned removable partial denture (RPD) using new proposals for calibrated gauges of 0.3 mm and 0.35 mm undercuts through the three-dimensional (3D) finite element methodology, and compare them with 0.25 mm and 0.5 mm gauges that are already existing in clinical practice., Materials and Methods: Kennedy class-I edentulous 3D models and their respective RPDs (InVesalius software; Rhinoceros and SolidWorks CAD) were created and exported to the finite element program HyperMesh 2019 for mesh configuration. In the following steps, axial loading (0º) of 40 N per point was performed, with 3 points on the molars and 2 points on the premolars, totaling 280 N unilaterally. The model was processed by the OptiStruct 2019 software and imported into the HyperView 2019 software to obtain the stress maps (MPa)., Results: The use of 0.30 and 0.35 mm calibrated gauges presented tensions similar to those with the 0.25 mm gauge (gold standard) and caused no significant damage to biological structures. The use of a 0.5 mm undercut caused greater traction force in the periodontal ligament of the abutments., Conclusions: The 0.35 mm undercut seems promising as it presented more favorable results in this simulation, on the other hand, a 0.5 mm undercut is greater than that necessary for retainers made of CoCr., Clinical Significance: This study aims to measure a new undercut gauge (0.35 mm) to increase the retention area in abutment teeth of removable partial dentures.