Heat-polymerized Acrylic Resin Research Articles

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.

Evaluation of enamel wear by 3 occlusal splint materials: An in vitro study

Statement of problemOcclusal devices used to manage bruxism have been commonly fabricated from polymethyl methacrylate with the powder-liquid technique. More recently, Vertex ThermoSens (VTS) and the biocompatible high-performance polymer (BioHPP), an optimized material having polyetheretherketone (PEEK) as its basis, have been used, but little is known about the wear of these materials on human enamel. PurposeThe purpose of this in vitro study was to assess via a mastication simulation test how 3 occlusal device materials affected the wear and roughness of enamel antagonists. Material and methodsA noncontact 3D optical profilometer was used to measure the enamel surface roughness (Ra) against 3 occlusal device materials: vertex regular, VTS, and PEEK high-performance polymer (BioHPP). A dual-axis mastication simulator was used to perform a 2-body wear test on specimens from each group. The test consisted of 10 000 cycles with a 70-N force and 5 to 55 °C thermocycling. Following simulated mastication, the weight of each specimen and the Ra change were compared with the Kolmogorov-Smirnov test, paired specimens t test, Wilcoxon signed-rank test, and 1-way analysis of variance (α=.05). ResultsThe polyamide group caused the lowest amount of enamel wear (P<.05), while the heat-polymerized acrylic resin group induced the largest amount of enamel wear (P<.05). For polyamide and PEEK, the change in enamel surface roughness exhibited a smooth texture, whereas it found a rougher surface for the heat-polymerized acrylic resin. ConclusionsAccording to this study, surface roughness and wear on human enamel were not correlated. PEEK is a promising material for the fabrication of occlusal devices.

Comparative evaluation of retention of record bases fabricated using conventional impression and modified digital scan for complete denture: An in vivo study

Background: In prosthetic dentistry, making an impression to replicate the oral health and tooth morphology is regarded as a crucial step. It is essential to ensure that the intraoral state is replicated as exactly as possible throughout this process, because any mistakes or inconsistencies could significantly impact the quality of the entire denture. In secondary impression, it’s crucial to capture the resilient oral mucosa (oral vestibule and soft palate) in order to acquire a satisfactory retention. As an alternative to conventional impression, digital scanning has been widely used in complete denture procedure. Although the digital scanning of edentulous ridges is feasible, scanning resilient oral tissues in complete denture still cannot be supported digitally. This study focuses on modifying the digital scan and comparison of retention of record bases fabricated from these modified digital scan to the record bases fabricated using conventional impression. Objectives: To compare the retention of record base prepared from conventional impression to the retention of record base from modified digital scan. Methodology: A total of 18 patients with edentulous maxillary arches will be recruited. A modified intraoral scan of the maxilla will be made on nine patients and on the remaining nine patients, a conventionally border moulded impression with a custom tray will be made. A record base with heat polymerized acrylic resin will be made on the definitive cast. Using the modified scanned image, the CAD-CAM bases will be milled. A dynamometer will be placed onto the record base; this will simulate the dislodging forces, thus clinically testing record base retention. Expected outcome: The record bases from modified digital scan will show equivalent or higher retention compared to record bases from conventional impression. Conclusions: By the end of the study, we will know whether resiliency of tissues can be recorded by modified digital scans.

Solution of 25% and 45% strawberry extract as stain extrinsic cleaning material on heat polymerised acrylic resin plates

Strawberries can be used as a stain remover because they contain ellagic acid which has the potential to make teeth white and eli-minate bad breath. This study examines the effectiveness of strawberry extract as an alternative cleaning agent for stains caused by extrinsic discolouration on heat polymerised acrylic resin (HPAR) plates. Using a pretest and posttest with control group de-sign, 24 RAPP samples were soaked in coffee solution for 7 days. On the 8th day, the colour change was observed using a spec-trophotometer on the HPAR plates. The samples were divided into four groups, namely soaking groups using 25%, 45% straw-berry extract, sodium hypochlorite, and distilled water for 14 days. On the 15th day, the colour change was observed. Data were processed with SPSS using paired t-test and one-way Anova test which showed significant differences in each treat-ment (p&lt;0.05), except for the distilled water group. It was concluded that 25% and 45% strawberry (Fragaria x annanassea) extract solution is effective as an alternative cleaning agent for stains due to extrinsic discolouration on HPAR plates.

Comparison of mechanical properties, surface roughness, and color stability of 3D-printed and conventional heat-polymerizing denture base materials

Statement of problemStudies on the mechanical, optical, and surface properties of 3-dimensionally (3D) printed denture base materials are scarce, and those available have reported conflicting results. PurposeThe purpose of this in vitro study was to compare the mechanical properties, surface roughness, and color stability of 3D-printed and conventional heat-polymerizing denture base materials. Material and methodsA total of 34 rectangular specimens (64×10×3.3 mm) were fabricated from each of the conventional (SR Triplex Hot; Ivoclar AG) and 3D-printed (Denta base; Asiga) denture base materials. All specimens underwent coffee thermocycling for 5000 cycles, and half in each group (n=17) were evaluated in terms of color parameters, color change (ΔE00), and surface roughness (Ra) before and after coffee thermocycling. The specimens then underwent a 3-point bend test. The remaining specimens in each group (n=17) underwent impact strength and Vickers hardness testing. Data were analyzed by the paired samples, independent samples, and Wilcoxon signed rank tests (α=.05). ResultsThe color change caused by coffee thermocycling in the 3D-printed group was higher than that in the conventional group (P<.001). Surface roughness significantly increased in both groups after coffee thermocycling (P<.001). The conventional group had higher surface roughness before coffee thermocycling, while the 3D-printed group had higher surface roughness after coffee thermocycling (P<.001). The flexural strength, flexural modulus, and surface hardness in the conventional group were significantly higher than those in the 3D-printed group (P<.001). However, the impact strength of the conventional group was lower than that of the 3D-printed group (P<.001). ConclusionsThe 3D-printed denture base material showed higher impact strength and surface roughness than the conventional heat-polymerizing acrylic resin. However, flexural strength and modulus, surface hardness, and color stability were lower in the 3D-printed group.

Effect of Chlorhexidine and Castor Oil on Surface Roughness of Heat-Cured Acrylic Resin Denture Base

Background: Heat-cured acrylic resin is the acrylic resin most often used to make denture bases. In its use as a denture base, heat-cured acrylic resin requires a disinfectant to clean it from contamination by microorganisms. Still, it does not affect other properties of the heat-cured acrylic resin. Objective: This study aimed to determine the effect of heat-cured acrylic resin denture base disinfection with chlorhexidine and castor oil on surface roughness. Materials and Methods: This research is laboratory experimental with 30 bar-shaped (50x20x3mm) heat-cured acrylic resin-denture base specimens samples were divided into two groups, with chlorhexidine 0.2% simulated 3, 4, and 5 years and with castor oil 10% affected 3, 4, and 5 years. The surface roughness was tested using the Roughness tester TR200. Data were analyzed using univariate statistics and an independent t-test (α = 0.05). Results: The research showed no significant effect in the disinfection of heat-cured acrylic resin denture base with 0.2% chlorhexidine and 10% castor oil on surface roughness of 3, 4, and 5 years (p 0.05). Castor oil of 10% can be used as a disinfectant for the heat-cured acrylic resin denture base because it does not affect the surface roughness. Conclusion: Chlorhexidine 0.2% and castor oil 10% had the same effect on changes in surface roughness on heat polymerized acrylic resin denture base.

THE SURFACE ROUGHNESS VALUE ALTERATION OF ACRYLIC RESIN IMMERSED IN 10% CINNAMON EXTRACT AS A DISINFECTING MATERIAL

The surface roughness of acrylic denture bases can be a reservoir for food debris and microorganisms. Surface roughness can result from disinfection procedures. Cinnamon (Cinnamomum burmanii) is a spice-producing tree which has aroma and taste and contains active substances that most act as antimicrobials, namely cinnamaldehyde and eugenol, which can be used as disinfectants. The purpose of this study was to determine the change in the value of the surface roughness of acrylic resin after being immersed in 10% cinnamon extract and 0.5% sodium hypochlorite as a disinfectant. The research was experimental. The samples were heat-polymerized acrylic resin plates immersed in 10% cinnamon extract, 0.5% sodium hypochlorite, and distilled water. The results showed a significant difference in the degree of roughness of the acrylic plate immersed in 0.5% sodium hypochlorite solution compared to 10% cinnamon extract. The acrylic plate immersed in cinnamon extract had a minor level of roughness (0,37 µm) compared to the plate immersed in 0.5% sodium hypochlorite solution (0,20 µm). A cinnamon extract of 10% did not affect the roughness of the acrylic plate.

Polymethylmethacrylate-Based Nanocomposites for Denture Base Fabrication: Impact of Nanoparticle Type and Concentration on the Color Change In Vitro

Background. Although the mechanical behaviors of PMMA were improved with nanoparticles addition, there is a lack of study on the color changes of nanocomposite denture base resin. This study aimed to assess and compare the color of nanocomposite denture base resin modified with different nanoparticles and concentrations. Materials and Methods. Three nanoparticles (zirconium dioxide (ZNP), titanium dioxide (TNP), and silicon dioxide (SNP)) were added to heat-polymerized acrylic resin in 3 and 7 wt% concentrations. A total of 70 acrylic discs (20 × 2 ± 0.03 mm) specimens were prepared while one without addition (control) and three main groups according to nanoparticles and two subgroups according to % (3ZNP, 7ZNP, 3TNP, 7TNP, 3SNP, and 7SNP) with total 70 acrylic discs (n = 10). Spectrophotometer was used for color change (ΔEab) followed by value conversion to National Bureau of Standards units (NBS) to relate the color alterations (ΔEab) to the clinical environment which aids in determining a threshold for clinical acceptance of the color change. ΔEab data were analyzed and compared using one- and two-way ANOVA tests followed by Bonferroni’s post hoc test (α = 0.05). Results. Two-way ANOVA showed that filler type (regardless of filler concentration) had a statistically significant effect on mean ΔEab ( P &lt; 0.001 ). Filler concentrations (regardless of filler type) showed a significant effect on mean ΔEab while the filler type and concentration interaction showed no significant effect on mean ΔEab ( P &lt; 0.001 ). One-way ANOVA in terms of filler types results showed a significant difference between mean ΔEab ( P &lt; 0.001 ), where TNP group showed the highest mean ΔEab followed by ZNP and SNP. Pair-wise comparison revealed that 3% concentration showed a significant lower mean ΔEab than 7% concentration ( P &lt; 0.001 ). Conclusion. Modification of heat-polymerized denture base resin with ZNP, TNP, or SNP causes clinically unacceptable color change. TNP produced the highest color change followed by ZNP and SNP, and the color change is concentration dependent; the color change increases as the concentration increases.

The Effect of Controlled Diabetic and Non-diabetic Saliva on Candida albicans Adherence to Heat Polymerized Acrylic Resin Discs

Background: Oral candidiasis is one of the most common infections in diabetic patients that may occur due to a decrease in salivary flow rate, alterations in the salivary composition, or both. This study aimed to investigate the effect of diabetic and non-diabetic saliva on Candida albicans adherence to the acrylic resin disc specimens, regardless of saliva volume. Methods: In this case-control study, the population consisted of 26 subjects in 2 groups (13 diabetic patients and 13 non-diabetic patients). In both groups, unstimulated whole saliva was collected. It was investigated for pH, salivary flow rate, and adhesion of C. albicans to polymethylmethacrylate disc. After preparing the polymethylmethacrylate discs, the samples were stored in diabetic saliva, non-diabetic saliva, and distilled water (negative control group) for 60 minutes at 37ºC. Then they were immersed in the yeast suspensions containing C. albicans and stained with gram stain. Yeast cells were counted using a light microscope. Results: The pH of unstimulated whole saliva in diabetic patients was significantly lower than in the control group. There was no significant difference between the flow rates of saliva in the two groups. Findings indicated that the adhesion of C. albicans to resin in diabetic saliva was higher than in non-diabetic saliva. Conclusion: This study showed the same amount of salivary flow rate in diabetic and non-diabetic individuals, lower pH, and higher Candida adherence to heat polymerization acrylic resin in the diabetic group.