Heat-polymerized Acrylic Resin Research Articles

The effect of soaking heat-polymerized acrylic resin denture base in avocado seed extract (Persea americana Mill.) on the inhibition of denture-plaque microorganisms biofilm growth

Background Heat polymerized acrylic (HPA) resins are known to have high porosity that contributes to increased surface roughness and microcrack formation in stress areas. This facilitates the attachment and growth of polymicrobial biofilms contributing to increased antimicrobial resistance. Many research had been carried out on avocado seeds, but no research that studies avocado seeds effect on denture-plaque microorganism biofilm on HPA resin has been found. Methods This study used 144 samples (n=144), namely HPA resin discs covered with mono-species and polymicrobial biofilms. The discs were soaked for 8 hours in the 5%, 10%, 15%, 20% avocado seed extract, positive control (alkaline peroxide), and negative control (aquadest). Each disc was shaken with a vortex mixer for 1 minute, and 100 μL was added into 96-well microplates with three times repetition and incubated for 24 hours. A microtiter plate biofilm formation assay was then conducted The inhibition values were determined from the percentage inhibition value formula which required absorption values from a microplate reader (595 nm). The research data were analyzed using a univariant test, and a one-way ANOVA test, accompanied by Welch ANOVA on non-homogenous data. Results In this research, it was found that the MBIC50 of avocado seed extract against the mono-species of C. albicans (5%), C. glabrata (5%), A. odontolyticus (15%), S. gordonii (15%), S. aureus (10%), while against polymicrobial was 20%. There was a significant effect of soaking HPA resin in avocado seed extract on the inhibition of mono-species and polymicrobial biofilms with a value of p<0.001 (p<0.05). Conclusion The MBIC50 of avocado seed extract in polymicrobial biofilm group was higher than that in the mono-species biofilm groups. Although alkaline peroxide showed higher inhibition value than that of the MBIC50 in polymicrobial biofilm group, 20% avocado seed extract was concluded effective as it inhibited >50% polymicrobial biofilm.

Effect of mechanical and chemical surface treatments on the repairing of milled and 3D-printed denture bases.

Ensuring a strong bond between chairside autopolymerized acrylic resin to denture base is essential for denture repair and reline procedures. However, there is no established protocol to enhance bond strength between autopolymerizing resin and computer-aided design and computer-aided manufacturing (CAD-CAM) denture base materials. The purpose of this study was to determine shear bond strength of CAD-CAM denture bases and autopolymerizing acrylic resin after mechanical and chemical surface treatments compared with heat-polymerized acrylic resin. Heat-polymerized, milled, and 3-dimensional (3D) printed denture bases were divided into 4 surface treatment protocols: none (control), airborne-particle abrasion (APA), tetrahydrofuran, and Vitacoll application. Autopolymerizing acrylic resin cylinders were bonded to denture surface. Shear bond strength and failure modes were determined after thermocycling. Denture base surfaces were assessed for surface roughness, surface morphology, and microhardness before and after surface treatment. Data was analyzed using two-way ANOVA and multiple comparison tests. The results showed that APA significantly increased shear bond strength and surface roughness of all denture base materials. Tetrahydrofuran and Vitacoll application improved shear bond strength of heat-polymerized acrylic resin, but did not reach the level achieved by APA. Conversely, tetrahydrofuran application improved bond strength of 3D-printed denture to the level of APA. Tetrahydrofuran and Vitacoll application significantly reduced denture base hardness, compared with control and APA. In conclusion, mechanical surface treatment using APA enhances the adhesion of autopolymerizing acrylic resin to heat-polymerized and CAD-CAM denture bases. Tetrahydrofuran and Vitacoll chemical surface treatment improved adhesion to heat-polymerized acrylic resin, with only tetrahydrofuran enhancing bond strength of 3D-printed denture to the level of APA. Without surface treatment, the highest bond strength was shown in 3D-printed denture base material.

Enhancing Removable Partial Dentures Hygiene: Investigating Mucolytic Agents and Biocides for Disrupting Biofilms and Improving Antimicrobial Efficacy.

This study evaluates the antibiofilm action of 2.5 mg/mL peracetic acid (PA), 0.5 mg/mL cetylpyridinium chloride (CPC), and 160 mg/mL N-Acetylcysteine (NAC) against multispecies biofilm of Streptococcus mutans, Staphylococcus aureus, Candida albicans, and Candida glabrata, developed on surfaces of heat-polymerizing acrylic resin (AR) and cobaltchromium (Co-Cr) alloy. A multispecies biofilm was grown on the surface of AR and Co-Cr specimens (Ø 12×3mm). After biofilm maturation, the specimens were immersed in experimental solutions and evaluated through biofilm viability (CFU) (n&#61;9), biofilm metabolic activity (XTT) (n&#61;9), biofilm-covered areas (Live/Dead) (n&#61;2), effects on the extracellular polymeric substance (EPS) (n&#61;2) and biofilm morphology (n&#61;1). Data were analyzed by ANOVA and the Tukey post-test or Kruskal-Wallis followed by the Dunn post-test (α&#61;.05). Overall, all evaluated solutions impacted biofilm viability. PA presented wider activity by reducing CFU of all microorganisms on both surfaces, XTT (P<.001) and Live/Dead (P<.001). NAC had a notorious effect in reducing the viability of bacteria without affecting the yeasts. NAC reduced XTT on AR (P&#61;.006) and Co-Cr (P&#61;.003) but did not reduce the aggregated biofilm layer. CPC had distinct effect according to the surface, being most effective in reducing CFU on AR than the Co-Cr surface. However, it did not influence XTT, and the amount of residual aggregated biofilm. PA provided the greatest antibiofilm action, while CPC and NAC showed intermediate action. Nonetheless, no solution was able to completely remove the biofilm adhered to the surfaces of heat-polymerizing AR and Co-Cr alloy.

Effect of aging on dimensional accuracy and color stability of CAD-CAM milled and 3D-printed denture base resins: a comparative in-vitro study

BackgroundThere is a lack of studies comparing the dimensional accuracy and color stability of denture base resins made using computer-aided design and computer-aided manufacturing (CAD-CAM) milling, 3-dimensional (3D) printing, and conventional denture processing techniques. This makes it challenging to determine the best method to fabricate complete dentures. The objective of this in vitro investigation was to assess and contrast the color stability and dimensional accuracy of denture base resins that were 3D printed and CAD-CAM milled, both before and after aging by thermocycling using digital surface matching technology and a benchtop laser scanner without using a spray, to optimize adaptation of the denture base and cast to minimize any imperfections and to evaluate the impact of the denture cleansing solution on the stability of color.MethodsEvaluation of the dimensional accuracy (n = 27) was completed on a sectional maxillary stone cast using a digital 3D-surface matching software before and after 5000 thermocycles. A spectrophotometer was used to measure the color change (△E00) of all disc specimens (N = 54) before and after 500 thermocycles and immersion in denture cleansing solution for 30 cycles (3 min each) daily for 6 days. The Kruskal Wallis test, Dunn’s post hoc test, Tukey’s test with Bonferroni adjustment, one sample t test and independent t test were used to statistically analyze the data (α < 0.05).ResultsThermocycling decreased the dimensional accuracy of the heat polymerized group at all 5 locations and the 3D-printed group at locations 1, 3 and 5 (P > .05), while it had no significant difference on the CAD-CAM milled group at all locations (P < .05). The color change (△E00) was lowest in the CAD-CAM milled group, moderate in the heat-polymerized group and highest in the 3D-printed group. After immersion in denture cleanser, the color change (△E00) was significantly higher in the 3 groups compared with after thermocycling (P > .001).ConclusionsCAD-CAM milled resins had the highest dimensional accuracy and the best color stability, conventional heat polymerized acrylic resins showed moderate change in dimensional accuracy and color stability, while the 3D- printed resin had the lowest dimensional accuracy and color stability after aging by thermocycling.

Comparative study for Enhancing Poly (methyl-methacrylate) (PMMA) Performance with Engineered Nanomaterials

Objectives:The current study was intended to evaluate and compare the effect of addition of Titanium Dioxide Nanoparticles versus Zirconium oxide nanoparticles to denture base materials regarding: impact strength and water sorption Materials and Methods: Thirty heat-polymerized acrylic resin specimens with the dimensions of (60x8x2 mm) were prepared according to the manufacturer’s instructions and divided into three groups each group 10 specimens first group was the control group , the Second group incorporated with 1.5wt% TiO2NPs (Titanium dioxide nanoparticles) to the heat-polymerized acrylic resin powder. And the third group incorporated with 1.5wt% ZrO2NPs (zirconium dioxide nanoparticles) to the heat-polymerized acrylic resin powder : impact strength was examined using Universal Testing Machine. A non-contact optical to compare different groups. water sorption were evaluated for all specimens. Data were statistically analyzed. Results:for heat cured acrylic resin with Zirconium dioxide nanoparticles for flexural stregth ,impact strength and water sorption was the highest value compared to Titanium Dioxide Nanoparticles Conclusions:ZrO2NPs nanoparticles have increased flexural stregth of resins as the concentration increase. For impact strength, water sorption compared to heat cured acrylic resin reinforced with Titanium Dioxide Nanoparticles

The effect of soaking heat-polymerized acrylic resin denture base in avocado seed extract (Persea americana Mill.) on the inhibition of denture-plaque microorganisms biofilm growth

Background Heat polymerized acrylic (HPA) resins are known to have high porosity that contributes to increased surface roughness and microcrack formation in stress areas. This facilitates the attachment and growth of polymicrobial biofilms contributing to increased antimicrobial resistance. Many research had been carried out on avocado seeds, but no research that studies the effect of avocado seeds on denture-plaque microorganism biofilm on HPA resin has been found. Methods This study used 144 samples (n=144), namely HPA resin discs covered with mono-species and polymicrobial biofilms consisting of Candida albicans, Candida glabrata, Actinomyces odontolyticus, Streptococcus gordonii, and Staphylococcus aureus. The discs were soaked for 8 hours in the 5%, 10%, 15%, 20% avocado seed extract, positive control (alkaline peroxide), and negative control (aquadest). Each disc was shaken with a vortex mixer for 1 minute, and 100 μL was added into 96-well microplates with three times repetition and incubated for 24 hours. The inhibition values were determined from the percentage inhibition value formula which required absorption values from a microplate reader (595 nm). Results In this research, it was found that the MBIC50 of avocado seed extract against the mono-species of C. albicans (5%), C. glabrata (5%), A. odontolyticus (15%), S. gordonii (15%), S. aureus (10%), while against the biofilm was 20%. There was a significant effect of soaking HPA resin in avocado seed extract of 5%, 10%, 15%, 20% on the inhibition of mono-species and polymicrobial biofilms of denture-plaque microorganisms with a value of p&lt;0.001 (p&lt;0.05). Conclusion The MBIC50 of avocado seed extract in polymicrobial biofilm group was higher than that in the mono-species biofilm groups. Although alkaline peroxide showed higher inhibition value than that of the MBIC50 in polymicrobial biofilm group, 20% avocado seed extract was effective in inhibiting polymicrobial biofilm because it was able to inhibit more than 50% polymicrobial biofilm.

Pengaruh Penambahan Kitosan Nano Gel Bermolekul Sedang pada Bahan Basis Gigi Tiruan Resin Akrilik Polimerisasi Panas Terhadap Kekuatan Transversal

Hot polymerized acrylic resin is one of the most widely used denture base materials, but this material has low transverse strength so it is easy to fracture. Transverse strength can be increased by adding reinforcing material Chitosan nano gel which is proven to increase transverse strength because the Chitosan nano gel has special properties such as biodegradability, biocompatibility, good mechanical properties and good layer formation properties. The purpose of this study was to determine the effect of adding Chitosan nano gel to heat polymerized acrylic resin denture base material on the transverse strength. The research design used in this study was an experimental laboratory. The research sample was a rectangular hot polymerized acrylic resin with a size of 65 mm x 10 mm x 2.5 mm±0. 5 for the calculation of transverse strength with a total sample of 27 samples. The results of this study indicate that the value of transverse strength added with 1.25% Chitosan nano gel is the most effective concentration to increase the transverse strength of the heat polymerized acrylic resin denture base material compared to the addition of 1% Chitosan nano gel and without the addition of chitosan nano gel.

Comparative Evaluation of Microhardness and Polymerization Shrinkage in Residual Zirconia Reinforced Provisional Restorations: An In Vitro Study.

Aim The aim of this study is to evaluate and compare the microhardness and polymerization shrinkage of polymethyl methacrylate reinforced with residual zirconia. Materials and methods A total of 360 resin samples were fabricated, with dimensions of 12 mm × 12 mm × 3 mm and 12 mm × 8 mm × 6 mm. Zirconia dust (40% by weight) was added to 180 of these samples. The study included four groups: Group A (autopolymerizing acrylic resin), Group H (heat-polymerizing acrylic resin), Group ZA (autopolymerizing acrylic resin with zirconia dust), and Group ZH (heat-polymerizing acrylic resin with zirconia dust). Each group consisted of 90 samples, with 45 samples used for evaluating microhardness and 45 samples for assessing polymerization shrinkage. Results Group ZH exhibited the highest microhardness at 6.06 ± 0.31 GPa. It also recorded the lowest shrinkage values, measuring 52.11 ± 3.21 mm³. Tukey's honestly significant difference test revealed that microhardness was significantly higher in Group ZA (4.53 ± 0.29 GPa) compared to Group A (3.51 ± 0.25 GPa). However, Group H (5.42 ± 0.26 GPa) demonstrated greater hardness than Group ZA. Regarding shrinkage, the addition of zirconia dust resulted in reduced values, with Group ZA (73.93 ± 3.55 mm³) showing less shrinkage compared to Group A (91.9 ± 6.38 mm³). Similarly, Group ZH (52.11 ± 3.21 mm³) had lower shrinkage than Group H (66.71 ± 5.97 mm³). Group A exhibited the highest shrinkage among all the groups. Conclusion Within the limitations of this study, it can be concluded that there is an increase in hardness and a decrease in shrinkage values of the resin with the addition of zirconia dust in heat and autopolymerizing acrylic resin used for the fabrication of provisional restorations. Zirconia-incorporated heat-activated resin showed superior microhardness and decreased shrinkage values. Although the addition of residual zirconia to autopolymerized samples demonstrated better hardness, it was observed that pure heat-polymerized samples showed greater hardness. Reusing computer-aided design and computer-aided manufacturing powder waste can cut down on economic losses and aid in environmental sustainability.

Influence of different printing orientations and post-polymerization time on the translucency of three-dimensional (3D) printed denture base resins.

To evaluate the effect of different printing orientations and post-polymerization time with thermal cycling on the translucency of 3D-printed denture base resins. Heat-polymerized (HP) acrylic resin specimens were fabricated and 3D-printed denture base materials (NextDent, ASIGA, FormLabs) were printed with different printing orientations (0, 45, 90 degrees) and subjected to different post-polymerization times (15-, 30-, 60-, and 90-min). All specimens were polished and immersed in distilled water for 1day at 37°C. CIEDE2000 was used to measure the translucency parameters (TP00) before and after thermal cycling (5000 cycles) recording the color parameters (L*, a*, b*) against a black and white background using a spectrophotometer. k-factors ANOVA followed by post hoc Tukey's test (α=.05) was performed for statistical analysis. The k-factors ANOVA test showed a significant effect of resin material, post-polymerization time, and printing orientation on translucency (p<0.001). In comparison to HP, all 3D-printed resins showed lower translucency with all post-polymerization times and printing orientation (p<0.001) except FormLabs resin (p>0.05). For all 3D-printed resins, the translucency increased, with increasing the post-polymerization time (p<0.001) and 60- and 90-min showed the highest translucency. For printing orientation, 90 and 45 degrees significantly showed high translucency in comparison to 0 degrees (p<0.001). FormLabs showed significantly higher translucency when compared with NextDent and ASIGA per respective printing orientation and post-polymerization time. The translucency significantly decreased after thermal cycling for all tested resins (p<0.001). The findings of this study demonstrated that the translucency of 3D-printed resins is influenced by the printing orientation, post-polymerization time, and resin type. As a result, choosing a resin type, and printing orientation, with a longer post-polymerization time should be considered since it may improve the esthetic appearance of the 3D-printed resins.

Effect of different surface roughening treatment on polyether ether ketone and acrylic resin bonding: A pilot study.

As polyether ether ketone (PEEK) is a relatively new material in dentistry, its bonding properties with regard to dental acrylic base materials are not fully known. To ensure the long-term success of removable dentures with a PEEK framework, the base materials must be well bonded to each other. The study aimed to investigate the effects of different kinds of surface roughening treatment on PEEK and acrylic resin bonding. Eighty PEEK specimens (N = 80) were randomly divided into 5 groups (n = 16 per group) and subjected to various surface roughening treatment (control, grinding, sandblasting, tribochemical silica coating (CoJet), and sulfuric acid etching). Heat-polymerized acrylic resin was applied to the treated surfaces of the PEEK specimens. The shear bond strength (SBS) test, environmental scanning electron microscopy (ESEM) analysis and three-dimensional (3D) surface topography analysis were performed. The statistical analysis of the data was conducted using the analysis of variance (ANOVA) and Tukey's multiple comparison test. The one-way ANOVA showed significant differences in the SBS values between the groups (p = 0.001). Sandblasting, tribochemical silica coating and sulfuric acid etching resulted in high SBS values (p = 0.001). The highest SBS values were observed in the sulfuric acid etching group (8.83 ±3.63 MPa), while the lowest SBS values were observed in the control group (3.33 ±2.50 MPa). The additional roughening treatment applied to the PEEK surface increases the bond strength with heat-polymerized acrylic resin.

Influence of Nanodiamond Incorporation on The Impact Strength of Repaired Denture Base acrylic resin: An in Vitro Study

Aim. This research aims to evaluate the effects of integrating Nanodiamond on the impact strength of repaired denture base resin. Methodology. Sixty acrylic resin specimens, sized 50×6×4 mm³ with a v-notch, were created from heat-polymerized acrylic resin. Ten specimens were kept intact while the other 50 specimens were sectioned to half and prepared with 45º beveling and a 2.5mm-repair gap. Nanodiamond particles were added to autopolymerized repair resin and repaired specimens were placed in five categories (n=10) according to Nanodiamond concentrations, unmodified as a control, 0.25%, 0.5%, 0.75%, and 1%ND by weight. Each specimen half was repositioned in a metal jig, and the repair resin was applied to the repair area. Subsequently, all specimens underwent finishing, polishing, and immersion in distilled water before Charpy's impact testing. Data analysis employed Tukey's post hoc test (with significance α=0.05) and one-way ANOVA. Results. Results showed that in comparison with the control group, the impact strength of repaired denture base resin significantly increased with 0.25% and 0.5% Nanodiamond addition to repair resin (significance at P ˂0.001). While it insignificantly decreased with 0.75% and 1% Nanodiamond (P=0.108 and P=0.615) and 1% presented the lowest value of impact strength (3.48 ± 0.43 KJ/m2). Conclusion. Adding a small amount of Nanodiamond to autopolymerized repair resin demonstrated an increase in the impact strength of repaired acrylic denture base resin. The highest impact strength was recorded with 0.25%ND (6.24±0.55 KJ/m2), followed by 0.5%ND (5.93±0.21 KJ/m2), whereas 1%ND exhibited the lowest impact strength value (3.48±0.43 KJ/m2).

Comparative evaluation of effectiveness of chemical, mechanical and chemico-mechanical methods of denture cleaning for removal of stains from heat polymerised acrylic resin denture base - An in- vitro study

An essential quality of acrylic resin denture bases is colour stability. Over time, acrylic resin bases have a tendency to attract stains, which causes the denture base's colour to alter. These modifications sometimes make the denture less aesthetically pleasing for the wearer, which leads to patient unhappiness and higher replacement costs. The study's objective was to evaluate and compare the effectiveness of cleaning dentures using chemical, mechanical, and chemico-mechanical methods for removing stains from the heat polymerized acrylic resin denture base.A total of 120 samples of heat polymerised acrylic resin were fabricated and stained using sambhar solution for 10 days under controlled conditions. The baseline optical density of the samples was determined. The samples were then subjected to stain removal procedure by either - chemical, mechanical or chemico-mechanical method. After which the optical density was again determined. The efficiency of the three methods used was determined by the difference in the optical density after staining and post cleaning and compared with the baseline optical density measured previously. The data was analysed using One-way ANOVA test. Post hoc comparison was made by Bonferroni t-test. p&amp;#60;0.0.5 was considered as statistically significant. Data analysis was done using the statistical software STATA version 13.0.The results suggested that the chemico-mechanical method was the best method for stain removal from the acrylic samples. However, the mechanical method of denture cleaning was found to be equally effective. The chemical method was least effective in removing stains from the surface of heat polymerised acrylic resin. The chemico-mechanical method was 95.16% effective and the mechanical method used was 92.12% effective, proving that the chemico-mechanical was the most effective method for removing stains from the acrylic resin amongst the 3 techniques compared.

Effect of Silica Nanoparticles On Flexural Strength And Surface Hardness Of Heat Polymerized Acrylic Resin.

Statement of problem. Various studies are present to increase the strength and surface hardness of heat polymerized acrylic resin by addition of material or surface treatments. The present study to evaluate an effect of silica nanoparticles on flexural strength and surface hardness of heat polymerized acrylic resin. Purpose. The purpose of this study was effect of silica nanoparticles, incorporated into Polymethyl Methacrylate, on flexural strength and surface hardness. The present study compared the effect of silanated and non silanated silica nanoparticles on the flexural strength and surface hardness of heat polymerized acrylic resin. Material and Methods. A total of 270 acrylic bars were fabricated, in two batches of 135 each, for testing flexural strength by universal testing machine and surface hardness determined using a digital micro Vickers hardness tester. The control group and subgroups had a sample size of 15 each with varied concentrations of nanoparticles by weight. The fabricated samples were tested for flexural strength and surface hardness. Results. Flexural strength was highest for PMMA (Polymethyl methacrylate) with 0.5% silanated silica nano particles as fillers. In both the groups, the flexural strength decreased with increase in filler concentration. Surface hardness was highest in the PMMA group with non-silanated nano particles as fillers at 5% concentration. In both groups the surface hardness improved with an increase in filler concentration. ANOVA and TUKEY’s HSD test were used. P&lt;0.05 was considered statistically significant. Conclusion. Lower concentrations of surface-treated silica nanoparticles should be used as fillers to enhance the flexural strength of commercially available heat polymerized acrylic resin. Bangladesh Journal of Medical Science Vol.23 (Special Issue) 2024 p.S79-S86

Evaluation of surface roughness, wettability and adhesion of multispecies biofilm on 3D-printed resins for the base and teeth of complete dentures.

This study evaluated the surface roughness, wettability and adhesion of multispecies biofilms (Candida albicans, Staphylococcus aureus and Streptococcus mutans) on 3D-printed resins for complete denture bases and teeth compared to conventional resins (heat-polymerized acrylic resin; artificial pre-fabricated teeth). Circular specimens (n=39; 6.0 mm Ø × 2.0 mm) of each group were subjected to roughness (n=30), wettability (n=30) and biofilm adhesion (n=9) tests. Three roughness measurements were taken by laser confocal microscopy and a mean value was calculated. Wettability was evaluated by the contact angle of sessile drop method, considering the mean of the three evaluations per specimen. In parallel, microorganism adhesion to resin surfaces was evaluated using a multispecies biofilm model. Microbial load was evaluated by determining the number of Colony Forming Units (CFU/mL) and by scanning electron microscopy (SEM). Data were subjected to the Wald test in a generalized linear model with multiple comparisons and Bonferroni adjustment, as well as two-way ANOVA (α=5%). The roughness of the conventional base resin (0.01±0.04) was lower than that of the conventional tooth (0.14±0.04) (p=0.023) and 3D-printed base (0.18±0.08) (p<0.001). For wettability, conventional resin (84.20±5.57) showed a higher contact angle than the 3D-printed resin (60.58±6.18) (p<0.001). Higher microbial loads of S. mutans (p=0.023) and S. aureus (p=0.010) were observed on the surface of the conventional resin (S. mutans: 5.48±1.55; S. aureus: 7.01±0.57) compared to the 3D-printed resin (S. mutans: 4.11±1.96; S. aureus: 6.42±0.78). The adhesion of C. albicans was not affected by surface characteristics. The conventional base resin showed less roughness than the conventional dental resin and the printed base resin. The 3D-printed resins for base and tooth showed less hydrophobicity and less adhesion of S. mutans and S. aureus than conventional resins.

Effectiveness of experimental dentifrices based on essential oils on biofilm on complete dentures: an in vitro study.

To conduct an in vitro evaluation of experimental dentifrices containing essential oils of Bowdichia virgilioides Kunth (BvK), Copaifera officinalis (Co), Eucalyptus citriodora (Ec), Melaleuca alternifolia (Ma) and Pinus strobus (Ps) at 1%. The variables evaluated were organoleptic and physicochemical characteristics, abrasiveness (mechanical brushing machine) simulating 2.5 years, and microbial load (Colony Forming Units - CFU/mL), metabolic activity (XTT assay) and cell viability (Live/Dead® BacLight™ kit) of the multispecies biofilm (Streptococcus mutans: Sm, Staphylococcus aureus: Sa, Candida albicans: Ca and Candida glabrata: Cg). Specimens of heat-polymerized acrylic resins (n=256) (n=96 specimens for abrasiveness, n=72 for microbial load count, n=72 for biofilm metabolic activity, n=16 for cell viability and total biofilm quantification) with formed biofilm were divided into eight groups for manual brushing (20 seconds) with a dental brush and distilled water (NC: negative control), Trihydral (PC: positive control), placebo (Pl), BvK, Co, Ec, Ma or Ps. After brushing, the specimens were washed with PBS and immersed in Letheen Broth medium, and the suspension was sown in solid specific medium. The organoleptic characteristics were presented by descriptive analysis. The values of density, pH, consistency and viscosity were presented in a table. The data were analyzed with the Wald test in a generalized linear model, followed by the Kruskal-Wallis test, Dunn's test (mass change) and the Bonferroni test (UFC and XTT). The Wald test in Generalized Estimating Equations and the Bonferroni test were used to analyze cell viability. All dentifrices showed stable organoleptic characteristics and adequate physicochemical properties. CN, Ec, Ps, Pl and PC showed low abrasiveness. There was a significant difference between the groups (p<0.001) for microbial load, metabolic activity and biofilm viability. It was concluded that the BvK, Ec and Ps dentifrices are useful for cleaning complete dentures, as they have antimicrobial activity against biofilm. The dentifrices containing Bowdichia virgilioides Kunth showed medium abrasiveness and should be used with caution.

Effects of Different Chemical Disinfectants on Physical Properties of Denture Base Acrylic Resin Material

Statement of the problem: There is still a lack of data regarding the effects of exposure to different chemical disinfectants on the color stability, light translucency, and surface roughness of dentures is limited. Objective: This study aims to investigate the impact of six different chemical disinfectants on the color change, translucency, and surface roughness properties of heat-polymerized denture base acrylic resin. Material &amp; Methods: Totally 70 rectangular blocks (10×10×2 mm) were polymerized from the heat-polymerized acrylic denture base resin material. The surfaces of the specimens polished with 600- and 1200-grit waterproof abrasive paper. Each specimen were immersed in six denture cleansers. The total immersion time of a specimen in selected chemical disinfectant was 36 hours. Color changes, translucency and, surface roughness were measured after immersion process. The results were statistically analyzed with 1-way ANOVA and the Tukey honestly significant difference (HSD) test (α=.05). Results: According to the results of the 1-way ANOVA test, significant differences were observed in the ∆E00, TP00 and Ra properties among the acrylic resin groups following immersion in chemical disinfectants (P&lt;0.05). ΔE00 value of the CG group was significantly higher than that of the NS, SH, G, and E groups (P&lt;0.05). The TP00 values of the NS and G groups were demonstrated significant differences compared with C group (P&lt;0.05). The Ra values of the SH, SP, G, CG and, E groups were significantly increased after immersion process, in comparison with C and NS groups (P&lt;0.05). Conclusions: Color stability, translucency and surface roughness of the denture base heat polymerized acrylic resin is influenced by chemical disinfectants.

In Vitro Evaluation of Candida albicans Adhesion and Related Surface Properties of CAD/CAM Denture Base Resins.

The aim of this study was to evaluate the surface roughness, contact angle, and adhesion of Candida albicans to computer-aided designing/computer-aided manufacturing (CAD/CAM) and heat-polymerized (HP) denture base materials. Specimens were allocated to six groups based on the composition of studied denture base materials, HP acrylic resin, milled resins (AvaDent and IvoCad), and 3D-printed resins (ASIGA, FormLabs, and NextDent). Ten specimens per group were used for each test (n = 10/test). Surface roughness and contact angles were analyzed using profilometer and goniometer, respectively. Adhesion of C. albicans was counted using colony-forming unit (CFU/mL). Means and standard deviations were calculated, and then one-way analysis of variance (ANOVA), followed by Tukey's post hoc test. Correlation of Candida adhesion and surface parameters was determined by using Pearson's correlation analysis. No statistically significant difference was noted in surface roughness between HP, milled, and 3D-printed denture base resins except NextDent, which showed significantly higher roughness in comparison to all other resins (p = 0.001). In terms of contact angle, milled resins had the lowest value, followed by HP, ASIGA, and FormLabs, whereas NextDent showed the highest contact angle (p = 0.001). C. albicans adhesion showed no significant difference between all denture base resins. A positive and significant correlation was found between C. albicans adhesion and contact angle (p = 0.003), while no correlation was reported between C. albicans adhesion and surface roughness (p = 0.523). Adhesion of C. albicans was similar in all tested specimens. Surface roughness showed no significant difference between all groups except NextDent, which had the highest value. Milled denture base resins had the lowest contact angle among all groups.

Which metal surface treatment improves the bond strength between metal alloys and acrylic resin in removable partial dentures? A systematic review.

The union of the metal removable partial denture framework to the heat polymerized acrylic resin is related to prosthesis longevity. However, methods to enhance this bond are not clear to clinicians and dental laboratory technicians. The purpose of this systematic review was to identify which metal surface treatments best increase the bond strength between heat polymerized acrylic resin and removable partial denture alloys. This review was carried out following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and registered in the International Prospective Registry of Systematic Reviews (PROSPERO) database (CRD42022384926). Electronic searches were carried out independently, by 3 examiners in Medline/PubMed, Scopus, and Web of Science databases, and in the nonpeer-reviewed literature via ProQuest. The electronic searches resulted in 4143 articles, with 4055 after removing duplicates. After reading the titles and abstracts, 37 articles were selected for reading in full-text version, from which 6 articles were included. All studies evaluated materials for conventional acrylic resin denture base (heat polymerized), processed by water bath, bonded to metal. For the metal framework alloys, cobalt chromium (Co-Cr) alloys were used in 2 studies, titanium (Ti) in 2 studies, and Co-Cr and Ti in the other 2 studies. Different metal surface treatments were used as airborne-particle abrasion with aluminum oxide (particle sizes of 50µm, 110µm, and 250µm) followed by the primer application and the isolated use of the primer, compared to the absence of isolated intervention or airborne-particle abrasion of the metal surface. Among the different primers used, those based on 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) showed the highest acrylic resin-to-metal bond strength values. Airborne-particle abrading the metal with Al2O3 followed by applying a 10-MDP-based primer, increased the bond strength between metal framework alloys and heat polymerized acrylic resin denture base material.

Evaluation The Effects of Ethylmethacrylate and Isobutylmethacrylate on Transverse Strength Of Heat-Polymerized Acrylic Resins

Background in order to regain esthetic, patients are given an ocular prosthesis. The majority of them are made of poly methyl methacrylate resin (PMMA), which is a popular material for maxillofacial prostheses including ocular prostheses, Fracture of poly methyl methacrylate occurs due to several reasons involving careless handling and falling of ocular prosthesis on hard surfaces, it is essential to strength the acrylic to improve the transverse strength of the resin. Materials &amp;methods :50 samples were constructed from heat cured acrylic resins and divided into three groups (1control and 2 experimental group) Each group had ten specimens. The two experimental groups comprised the IBMA, EMA monomer at 1% and 2% concentrations, respectively. Such samples were prepared with dimensions of 65 mm x 10 mm x 2.5mm ± 0.1 length, width and thickness respectively according to (ADA specification, No.12, 1999). All the samples were tested for transverse strength. All data were analyzed using SPSS version 20. Tukey test was used for comparison between the groups.Results: There were highly significant differences (P&lt;0.001) on the transverse strength between the control group and EMA, IBMA copolymers. Conclusion: The scleral acrylic resin incorporation with 1% and 2% wt % EMA, IBMA copolymers showed insignificant increase in transverse strength

Comparative evaluation of flexural strength of heat polymerized acrylic resin denture base material repaired with auto- polymerized acrylic resin using surface treated reinforcement materials – An in vitro study

: The purpose of this vitro study was to comparatively evaluate the flexural strength of repaired denture base resin using different surface treated reinforcement materials.According to ADA specification No. 12, typical heat polymerized acrylic resin specimens were created, and various repairs were made to them. Autopolymerizing resin was used for repair. The flexural strength was evaluated using the INSTRON universal testing equipment on a total of 90 samples (with 15 samples in each group). In this study the highest value of flexural strength was obtained for group in which the reinforcement was done with surface treated half round wires that were sandblasted, etched followed by application of alloy primer.: Specimens repaired with reinforcement increases flexural strength. Reinforcement with silanized woven roving e glass fibers showed significant increase in flexural strength compared to unreinforced specimens. There was no statistical difference between the samples repaired with sandblasted wires and etched wires group.