Denture Base Resin Research Articles

Air-polishing technology is an effective alternative chairside method for cleaning dentures.

To investigate the efficiency and abrasiveness of air-polishing on different types of denture base acrylic resins and whether air-polishing can be an effective technique to clean dentures chairside. A total of 60 specimens were prepared (n = 20/group); heat-polymerized polymethyl methacrylate (PMMA) (G1), subtractive manufacturing (SM) (G2) and additive manufacturing (AM) denture base resins (G3). Equal number of specimens in each group were stained with permanent marker or nail polish and pumice mixture to mimic calcified biofilm. All specimens were treated using EMS Airflow® Prophylaxis Master with two different powders; erythritol or sodium bicarbonate powder, following manufacturer instructions. Efficacy of the powders and surface roughness of the specimens were measured. Scanning electron microscopy imaging was captured for qualitative observation. The highest efficacy for stain removal was found in erythritol powder on G1 (98.06% ± 1.304%). The lowest was found in the erythritol powder on G3 (91.83% ± 3.611%). The highest efficacy for biofilm removal was found in sodium bicarbonate powder on G3 (71.49% ± 8.607%), and the lowest was found in erythritol powder on G2 (11.64% ± 4.68%). Only AM resins had statistically significant increases in surface roughness with the use of erythritol powder (p < 0.001). The use of sodium bicarbonate powder significantly increases surface roughness of heat-polymerized (p < 0.025) and AM resins (p < 0.724). Air-polishing technology has shown to be effective and suitable for cleaning dentures. The sodium bicarbonate powder showed superior efficacy in cleaning dentures compared to the erythritol powder. Both powders show varyingly increase roughness depending on denture resin.

Effect of polishing and denture cleansers on the surface roughness of new-generation denture base materials and their color change after cleansing.

To evaluate the effect of polishing and denture cleansers on the surface roughness (Ra) of new-generation denture base materials that are additively, subtractively, and conventionally fabricated, while also assessing their color change after cleansing. One hundred and fifty disk-shaped specimens (Ø10×2mm) were prepared from five denture base materials (one subtractively manufactured nanographene-reinforced prepolymerized polymethylmethacrylate (PMMA) (SM-GC), one subtractively manufactured prepolymerized PMMA (SM-PM), two additively manufactured denture base resins (AM-DT and AM-ND), and one heat-polymerized PMMA (CV) (n = 30). The Ra of the specimens was measured before and after conventional laboratory polishing, while color coordinates were measured after polishing. Specimens were then divided into three subgroups based on the denture cleanser: distilled water, 1% sodium hypochlorite (NaOCl), and effervescent tablet (n=10). The Ra and color coordinates were remeasured after nine cleansing cycles over a period of 20 days. The CIEDE2000 formula was used to calculate the color differences (ΔE00). Two-way analysis of variance (ANOVA) was used to analyze the Ra values before (n = 30) and after (n = 10) cleansing, while repeated measures ANOVA was used to analyze the Ra of material-time point pairs within each denture cleanser (n = 10). ΔE00 data after denture cleansing was also analyzed by using two-way ANOVA (n = 10) (α = 0.05). Before polishing, Ra varied significantly among the materials. SM-GC and SM-PM had the lowest and AM-ND the highest Ra values (P<0.001). Polishing significantly reduced Ra of all materials (P<0.001), and after polishing, Ra differences among materials were nonsignificant (P≥0.072). Regardless of the denture cleanser, the Ra of AM-DT, AM-ND, and CV was the highest before polishing when different time points were considered (P<0.001). After cleansing, AM-ND had the highest Ra of all the materials, regardless of the cleanser (P≤0.017). AM-DT had higher Ra than SM-PM when distilled water (P = 0.040) and higher Ra than SM-GC, SM-PM, and CV when NaOCl was used (P<0.001). The type of cleanser significantly influenced the Ra of AM-DT, AM-ND, and CV. For AM-DT, NaOCl led to the highest Ra and the tablet led to the lowest Ra (P≤0.042), while for AM-ND, distilled water led to the lowest Ra (P≤0.024). For CV, the tablet led to lower Ra than distilled water (P=0.009). Color change varied among the materials. When distilled water was used, SM-GC had higher ΔE00 than SM-PM and AM-DT (P≤0.034). When NaOCl was used, AM-ND had higher ΔE00 than SM-GC, SM-PM, and AM-DT, while CV and SM-GC had higher ΔE00 than SM-PM and AM-DT (P≤0.039). Finally, when the tablet was used, AM-ND and CV had the highest ΔE00, while AM-DT had lower ΔE00 than SM-GC (P≤0.015). The tested materials had unacceptable surface roughness (>0.2μm) before polishing. Roughness decreased significantly after polishing (<0.2μm). Denture cleansers did not significantly affect the surface roughness of the materials, and roughness remained clinically acceptable after cleansing (<0.2μm). Considering previously reported color thresholds, AM-ND and CV had unacceptable color change regardless of the denture cleanser, and the effervescent tablet led to perceptible, but acceptable color change for SM-GC, SM-PM, and AM-DT.

Three-dimensionally printed denture base resins modified by nanoglass particles and carbon nanotubes

Statement of problemThree-dimensionally (3D) printed denture base resins exhibit inferior mechanical properties compared with conventional and milled ones, a problem affecting their long-term clinical use. Improved 3D printed resins are required. PurposeThe purpose of this in vitro study was to determine whether a 3D printed denture base resin with nanoglass particles and multiwalled carbon nanotubes (MWCNTs) would exhibit enhanced mechanical properties. Material and methodsThe nanoglass particles and MWCNTs were silane coated and added to the resin to obtain the following groups: Control, resin modified with nanoglass particles with 2 percentages, 0.25 wt%, and 0.5 wt%; resin modified with MWCNTs with 2 percentages, 0.25 wt%, and 0.5 wt%; and a combination group with 0.25 wt% of each filler type. The printed specimens (N=330) were tested before and after thermocycling (600 cycles) for flexural strength (FS) and elastic modulus (n=22) by using a universal testing machine and for impact strength (IS) (n=22) by using a Charpy impact tester. The fractured impact specimens were then evaluated by using scanning electron microscopy (SEM). The surface roughness (Ra) (n=11) was assessed by using a profilometer. For data analysis, the 2-way ANOVA test was used for the analysis of FS, elastic modulus, and IS, and the 3-way ANOVA test was used for Ra with a subsequent Tukey post hoc test. Percentage change was compared among groups by using the Kruskal-Wallis test, followed by the Dunn post hoc test with Bonferroni correction (α=.05). ResultsThe filler content and thermocycling revealed a significant main interaction effect (P<.001) on FS, elastic modulus, and IS, with the 0.5% nanoglass group displaying the highest percentage decrease after thermocycling. The SEM images of fractured impact specimens revealed a brittle failure in the control and nanoglass groups. In contrast, the groups containing MWCNTs and the combination group displayed intermediate to ductile failure. Moreover, a significant inclusive interaction effect (P<.001) was found between the filler content, thermocycling, and polishing on surface roughness, with the 0.5% nanoglass group revealing the highest percentage increase in Ra of the polished surface after aging. ConclusionsThe addition of nanoglass and MWCNTs led to a significant improvement in the FS, elastic modulus, and IS of the 3D printed resin. The combination group displayed the least percentage change among all groups regarding the FS and IS, displaying intermediate to ductile failure. The control revealed the least percentage change in elastic modulus after thermocycling but with lower peak values compared with all other groups.

Flexural Strength of Heat Cure Denture Base Resin incorporated with Curcumin: An In-Vitro Study

Introduction: Acrylic resin when used for fabrication of denture is susceptible for microbial colonization. Many antimicrobial agents have proven effective against the microbial colonization when they were incorporated into the acrylic resin but adding anything into the acrylic resin can alter its mechanical properties resulting into unacceptable intraoral use. This study was done to evaluate ifadding an antimicrobial agent, Curcumin, alters the flexural strength of acrylic agent. Methods: 172 acrylic strips were fabricated. They were divided equally into 4 groups depending upon concentration of curcumin as Control, T1: 1% curcumin, T2: 3% curcumin and T4: 5% curcumin. Flexural strength was tested using 3-point bend test using Universal Testing Machine. Results: There was no significant difference in values of mean flexural strength for control, 1% and 3% curcumin groups. There was significant difference in the mean value between control and 5% curcumin group. Conclusion: 1% and 3% curcumin can be incorporated into acrylic resin without significantly altering its mechanical properties.

Investigating the biocompatibility, flexural strength, and surface roughness of denture base resin containing copper oxide nanoparticles: An in vitro study

AimThis study aimed to evaluate the biocompatibility, flexural strength, and surface roughness of polymethyl methacrylate (PMMA) containing Copper Oxide Nanoparticles (CuO NPs) at different concentrations. Methods25 heat-polymerized PMMA wax patterns fabricated in 5 groups containing 0.5, 5, 50, and 500 μg/ml CuO NPs and nanoparticle (NP)-free PMMA discs were prepared. 5 growth mediums (DMEM with 10% FBS and 1% penicillin-streptomycin) without disks were also incubated similarly to serve as the control groups. The cytotoxicity of the discs was measured by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay on cultured Human Gingival Fibroblasts. The number of 1.3 × 104 cells were seeded in each well of 96-well plates (5 wells for the extract of each specimen). Days 1, 3, 5, and 7 were the intervals that the culture media were in direct contact with the PMMA discs for either 24 or 72 h. After that, a total of 40 specimens with 65 × 10 × 2.5 mm dimensions were prepared in five groups (n = 8). The specimens were subjected to a rugosimeter for the evaluation of surface roughness. The flexural strength test was performed using a universal testing machine. Microscopic evaluation was performed for the dispersion of the NPs. Non-parametric Kruskal-Wallis test and parametric one-way ANOVA test were used for data analysis. ResultsThe samples containing 500 μg/ml NPs showed the lowest percentage of cell viability at all incubation periods, while the highest cell viability was observed in NP-free PMMA 24 h after the seventh day of incubation. NPs at 50 and 500 μg/ml concentrations showed strongly significant differences in cytotoxicity compared to the 0 concentration and the control group (p < 0.001). Although all the samples demonstrated an increasing pattern of cell viability on the third, fifth, and seventh days, the percentage of cell viability was significantly lower after 72 h than after 24 h in all incubation periods (p < 0.001). NPs significantly increased flexural strength (p = 0.005) but did not affect the surface roughness of the PMMA discs (p = 0.396). SignificanceThe CuO NPs were cytotoxic only when applied in high concentrations, but presented a descending trend over time. No cytotoxic effect was observed in the experimental groups after seven days of incubation. Furthermore, CuO NPs increased flexural strength, but the surface roughness of the PMMA discs was not affected.

In Vitro Evaluation of Candida albicans Adhesion on Heat-Cured Resin-Based Dental Composites.

Microbial adhesion on dental restorative materials may jeopardize the restorative treatment long-term outcome. The goal of this in vitro study was to assess Candida albicans capability to adhere and form a biofilm on the surface of heat-cured dental composites having different formulations but subjected to identical surface treatments and polymerization protocols. Three commercially available composites were evaluated: GrandioSO (GR), Venus Diamond (VD) and Enamel Plus HRi Biofunction (BF). Cylindrical specimens were prepared for quantitative determination of C. albicans S5 planktonic CFU count, sessile cells CFU count and biomass optical density (OD570 nm). Qualitative Concanavalin-A assays (for extracellular polymeric substances of a biofilm matrix) and Scanning Electron Microscope (SEM) analyses (for the morphology of sessile colonies) were also performed. Focusing on planktonic CFU count, a slight but not significant reduction was observed with VD as compared to GR. Regarding sessile cells CFU count and biomass OD570 nm, a significant increase was observed for VD compared to GR and BF. Concanavalin-A assays and SEM analyses confirmed the quantitative results. Different formulations of commercially available resin composites may differently interact with C. albicans. The present results showed a relatively more pronounced antiadhesive effect for BF and GR, with a reduction in sessile cells CFU count and biomass quantification.

Removable complete denture with a metal base: Integration of digital design and conventional fabrication techniques.

Digitally-designed removable complete dentures are typically composed of a resin denture base without a metal framework. However, metal denture bases are preferable as resin bases are more susceptible to fracture. Therefore, this article introduces a unique technique that integrates computer-aided design (CAD) and conventional resin processing for the fabrication of removable complete dentures with a metal framework. A maxillary complete denture with a metal base and a mandibular implant-retained overdenture reinforced with a metal framework were fabricated. The dentures were designed using CAD software and a tooth library. The denture bases were milled from wax disks, and artificial teeth were placed to complete the wax dentures. The metal frameworks were also designed using CAD software and produced via casting of printed resin patterns. Finally, conventional denture processing techniques were applied to obtain dentures with metal frameworks. A digitally designed, removable complete denture with a metal base can be successfully fabricated using the described technique, which merges digital design and conventional methods. This article demonstrates the feasibility and potential advantages of this innovative approach in denture fabrication. The presented technique provides the following advantages: digital design features, precise space above implant overdenture attachments for a metal framework, convenience of esthetic evaluation with printed trial dentures, long-term data storage and duplication, reliable bond between the artificial teeth and denture base, and enhanced strength of the removable complete denture due to the metal reinforcement.

Bond strength of relined print and conventional denture base resins after aging

Objectives: To compare the bond strength of printed and conventionally produced denture base resins to reline resins after being submitted to a physical-chemical aging process. Methods: Sixty specimens (10×10×3.3 mm) of two printed (V-Print Dentbase and Denture 3D+) and one conventionally produced (Probase Hot) denture base resins were relined with two acrylic resins: Ufi Gel Hard C and Probase Cold (n=10). The specimens were submitted to 1000 cycles of thermal fluctuations (5-55ºC) and 28 days of pH cycles using pH=3 (8 h/day) and pH=7 (16 h/day). Then, the shear bond strength was evaluated (1 KN; 1 mm/min), and the failure mode was classified as adhesive, cohesive, or mixed type. Data were analyzed with Kruskal-Wallis and t-tests (=0.05). Results: Bond strength values ranged from 8.9 to 21.5 MPa. No statistically significant (p=0.07) differences were found between the bond strength of the three denture base acrylic resins. The reline resin did not significantly (p=0.07) affect the bond strength of the two printed resins. However, relining the Probase Hot with Probase Cold yielded a higher bond strength (p&lt;0.001) than with Ufi Gel Hard C. Only the Probase Hot-Ufi Gel Hard C group revealed 100% of failures classified as adhesive type. Conclusions: The two printed denture base resins obtained similar bond strength to conventionally produced denture base resin after being submitted to thermal and chemical aging

The Cytotoxic Effect of Thermoplastic Denture Base Resins: A Systematic Review.

Partial or complete dentures are constructed from thermoplastic resins that are thermally processed and molded. This review examines the presently available evidence for the cytotoxicity of thermoplasticized denture base resins on human gingival epithelial cells, adipose cells, and fibroblasts; human amnion fibroblasts; and mouse fibroblasts. Electronic searches were performed on PubMed, Scopus, Web of Science, and Google Scholar databases to identify relevant articles to be included in the review until September 2022. Clinical, in vivo, and in vitro studies in English language were searched for. The quality of the studies was assessed using the Toxicological data Reliability Assessment tool (ToxRTool) developed by the European Commission's Joint Research Centre. GRADE assessment was used to evaluate the certainty of evidence. Seven in vitro studies were included in the review. The overall risk of bias was determined to be high, with the majority of studies assessed found to be reliable with restrictions or not reliable. Only two studies were considered reliable without restrictions based on ToxRTool assessment. The effect of thermoplastic denture base resins on viability and cell adherence of human gingival or amnion fibroblasts and mouse fibroblasts (L929s) is not significant. Conditioned media from unpolished specimens of resins were significantly more toxic to cultured cells than those from polished specimens. This may be of concern in cases of poor post-processing of dentures. Based on the limited evidence available, there is low-certainty evidence that thermoplastic denture base resins appear to be biocompatible and show insignificant cytotoxicity. Further well-designed trials adhering to standard reporting guidelines and using objective measures are necessary before outlining universal guidelines for best practice. Long-term in vivo and clinical assessment is necessary to corroborate laboratory findings with clinical outcomes. Denture base resins are in constant contact with oral tissues, and cytotoxic components released by the resins may irritate or inflame the tissues or provoke an allergic response.

An In Vitro Comparative Study of Maxillary Denture Base Retention Between Conventional Fabrication and 3D Printed Techniques

Objective: Many researchers have attempted to assess 3D printing as a manufacturing method to be used as an alternative for theconventional means. The current study aimed to determine the feasibility of 3D printed complete dentures in terms of retention.Methods: An edentulous maxillary model with an overlaying layer of mucosa was fabricated by 3D printing, using two different resinsfor the mucosa and model, which were then glued together to establish the final model. Afterwards, 8 single step putty and washimpressions were recorded with addition silicone. Each impression was scanned with a laboratory scanner. From each impression astone cast was fabricated on which a conventional baseplate was constructed by heat polymerized PMMA with the pack and presstechnique. Meanwhile, from the 8 STL files of the scanned impressions, 8 baseplates were designed and printed with the denture baseresin. Next, each of the 16 baseplates were connected to a loop at their center. Finally, the retentive value of all baseplates was measured by means of the universal testing machine. A statistical analysis was performed to evaluate the significance of retentive difference between the two groups.&#x0D; Results: The statistical analysis revealed that the printed dentures were significantly more retentive than the conventional, with a p-value of less than 0.029 and mean values of 15.0462 N and 12.05 N respectively.&#x0D; Conclusions: This study concluded that 3D printed complete dentures were significantly more retentive than the conventionallyfabricated dentures.

Flexural Properties of Heat-Polymerized PMMA Denture Base Resins Reinforced with Fibers with Different Characteristics.

Polymethylmethacrylate (PMMA) has been the most-widely used denture base material in prosthetic dentistry for the last 80 years. It is still one of the best alternatives when new methods are inapplicable. Due to the lack of some physical inadequacies occurring during cyclic use and accidental situations, various reinforcement strategies such as using nanoparticles, wires, fibers, and meshes have been investigated and reported. In this study, it was aimed to conduct a comparative investigation of the effect of fiber additives with different characteristics on the flexural properties of heat-cured PMMA denture base resins. Glass fibers (GFs), polypropylene fibers (PPFs), and carbon fibers (CFs) having 3, 6, and 12 mm lengths and 0.25, 0.50, and 1.0% concentrations (v/v) were used for the reinforcement of PMMA denture base resins. The flexural properties (flexural strength, flexural modulus, and maximum deformation) were determined using a three-point bending test, and three-way ANOVA analyses with Bonferroni corrections were performed on the test results. The morphologies of the fracture surfaces were analyzed using scanning electron microscopy. All three fibers exhibited reinforcement in the flexural strength (p < 0.001) and flexural modulus (p < 0.001) regardless of their length and concentration. The group with 1.0% 12 mm CF-reinforced PMMA exhibited the greatest flexural strength (94.8 ± 8.8 MPa), and that with 1.0% 3 mm GFs displayed the lowest flexural strength (66.9 ± 10.4 MPa) among the fiber-reinforced groups. The greatest value of the flexural modulus was displayed by the 1.0% 3 mm CF-reinforced resin (3288.3 ± 402.1 MPa). Although the CF-reinforced groups exhibited better flexural properties, CFs are not favorable for use as reinforcement in practice due to the dark gray discoloration of the denture base resin. It was concluded that PPF is a promising material for the reinforcement of heat-cured PMMA denture base resins.

Effect of Different Chemical Surface Treatments on the Shear Bond Strength of Acrylic Teeth With Different High-Impact Denture Base Resins.

Introduction The debonding of acrylic teeth from the denture base, particularly in cases of prominent ridges, is a common problem faced by clinicians and patients. The present study was conducted to assess the effects of various chemical treatments on the shear bond strength (SBS) of acrylic teeth bonded to different high-impact denture base materials. Materials and methods The present in vitro study was conducted on 80 wax specimens with acrylic teeth bonded to two high-impact denture base materials (DPI Tuff (DPI Dental Products of India Ltd, Mumbai) and Trevalon HI (Trevalon HI, Dentsply, Karnataka)). The two main groups were further divided into four subgroups of 10 specimens each, depending on the chemical treatment at the ridge lap area of the tooth: control group without any chemical treatment, chemical surface treatment (CST) with dichloromethane and monomer mix, CST with ethyl acetate, and CST with acrylic adhesive cyanoacrylate. The SBS was tested using a universal testing machine (UTM). Analysis of variance (ANOVA) and post-hoc Tukey tests were used for statistical analyses. Results The mean SBS of Group A (DPI Tuff) was 111.75 Nas compared to 118 N in Group B (Trevalon HI). The differences were statistically significant (p<0.05). ANOVA and post-hoc Tukey's tests revealed significant differences between subgroups. The highest mean SBS was noted with a dichloromethane and monomer mix (1:1 volume), followed by the ethyl acetate, control, and cyanoacrylate subgroups. Conclusion The cross-linked acrylic teeth treated with a dichloromethane and monomer mixture (1:1 by volume), processed with Trevalon HI high-impact denture base resin had the highest SBS and thus were indicated for bonding teeth with the suggested denture base.

Application of organoselenium in inhibiting Candida albicans biofilm adhesion on 3D printed denture base material.

Denture Stomatitis, a chronic mucosal inflammation associated with Candida albicans, is common among denture wearers. Several health conditions have been linked to chronic Candida infections. The complex, multifactorial nature of denture stomatitis requires the continuous pursuit of effective long-term solutions. The present in vitro study investigated the effect of incorporating organoselenium into 3D-printed denture base resin on C. albicans adhesion and biofilm formation. Thirty disks were fabricated using 3D-printed denture base resin and assigned to three experimental groups (10/group): disks without organoselenium (control), disks with 0.5% organoselenium (0.5%SE), and disks with 1% organoselenium (1%SE). Each disk was incubated with approximately 1 × 106 cells/mL of C. albicans for 48 h. Microbial viability (CFU/mL) was quantified by the spread plate method, while Confocal laser scanning microscopy and scanning electron microscope were performed for quantifying the biofilm thickness and examining biofilm morphology, respectively. Data were analyzed using One-way ANOVA with Tukey's multiple comparisons test. CFU/mL was significantly (p<0.05) higher in Control when compared with 0.5%SE and 1%SE, but no significant difference between 0.5%SE and 1%SE. A similar trend was observed with biofilm thickness except that there was no significant difference between the Control and 0.5%SE. There was C. albicans biofilm adhesion on the Control disks, with yeast cells and hyphae formation, whereas on 0.5%SE and 1%SE, there was inhibition of yeast cells transition to hyphae formation. Incorporation of organoselenium into 3D-printed denture base resin was effective in reducing C. albicans biofilm formation and growth on denture base material.

Feasibility of microencapsulated phytochemical as disinfectant for inhibition of Candida albicans proliferation on denture base produced by digital light processing.

A proper disinfection of denture is vital to prevent a fungal infection. A study on the feasibility of microencapsulated phytochemical as complementary disinfectant and its interaction with effervescent tablet immersion on denture base resin is lacking. The aim of this study was to examine the feasibility of phytochemical-filled microcapsules as disinfectant for the inhibition of Candida albicans (C. albicans) attachment on the denture base produced by digital light processing (DLP). 54 denture base specimens uniformly mixed with or without 5wt% phytochemical-filled microcapsules were prepared using DLP. Fungal cells were inoculated onto the surfaces of the specimens, which were divided into three different disinfection treatment groups (n = 9): 1) none, 2) sterile tap water immersion for 15 min, and 3) effervescent tablet immersion for 15 min. After each treatment, the biofilm on denture surface was stained with a crystal violet solution to measure the absorbance. The number of fungal colonies was counted as colony-forming units (CFU) per mL. Morphological changes were examined by microscopy. An aligned rank transform analysis of variance was performed to analyze the interaction of presence of microcapsule and disinfection condition, with statistical significance set at P < 0.05. Both for the absorbance and CFU, there was no significant interaction between the presence of microcapsules and disinfection conditions (P = 0.543 and P = 0.077, respectively). The presence of microcapsules was statistically significant (both P < 0.001), while the effect of disinfection condition was not significant (P = 0.165 and P = 0.189, respectively). Morphological changes in fungi were detected in the groups containing microcapsules, whereas undamaged hyphal structures were found in those without microcapsules, irrespective of disinfection treatments. The presence of phytochemical-filled microcapsules significantly reduced the adhesion of C. albicans and inhibited its proliferation on denture surfaces, regardless of disinfection conditions.

Effect of denture cleansers on color stability and surface roughness of denture bases fabricated from three different techniques: Conventional heat-polymerizing, CAD/CAM additive, and CAD/CAM subtractive manufacturing.

Denture base materials are commonly exposed to different denture cleansers which can affect their essential properties. This study aimed to assess the effect of denture cleansers on color stability and surface roughness of poly methyl methacrylate (PMMA) denture bases fabricated from different techniques: Conventional heat-polymerizing, CAD/CAM additive and CAD/CAM subtractive. In this in vitro study, 24 disc-shaped specimens were fabricated by the mentioned methods for each group. The initial color and surface roughness of specimens were recorded. The specimens were randomly divided into three subgroups (n = 8): a control subgroup (distilled water), and two experimental subgroups of bioactive oxygen tablet (Corega) and 1% sodium hypochlorite solution. Then they were immersed in the solutions simulating 180 days of clinical use. Color change (∆E) was measured by a spectrophotometer according to the CIE L*a*b* color space and the American National Bureau of Standards (NBS = 0.92 × ∆E). Final surface roughness was recorded by a profilometer and its change was calculated. The Kruskal-Wallis test followed by the Wilcoxon signed rank test were used for statistical analyses (α = .05). The conventional and CAD/CAM subtractive groups showed an increase in surface roughness following immersion in hypochlorite solution (p < .05). After immersion in the solutions, the highest surface roughness was noted in the conventional group, and the lowest in the CAD/CAM additive group. The CAD/CAM additive group experienced a significant color change in hypochlorite solution (p < .05) and showed the highest color change while the CAD/CAM subtractive group showed the lowest color change in all denture cleanser solutions. Although the CAD/CAM additive denture base resins had the lowest surface roughness after exposure to denture cleanser solutions, they showed significant color change, which should be taken into account. Using hypochlorite as a denture cleanser should be cautioned due to its negative effects on the surface roughness and color stability of denture base materials.

Effect of build angle, resin layer thickness and viscosity on the surface properties and microbial adhesion of denture bases manufactured using digital light processing

ObjectivesTo investigate differences in the surface properties and microbial adhesion of denture base resins for digital light processing (DLP) with varying resin layer thicknesses (LT), build angles (BA), and resin viscosities. MethodsTwo denture base resins for DLP with different viscosities (high and low) were used to prepare disk specimens applying two manufacturing parameters: 1) LT (50 or 100 μm) and 2) BA (0-, 45-, and 90-degree). Surface roughness and contact angle values were measured on the test surfaces (n=10 per group). Streptococcus oralis and Candida albicans absorbance was measured to assess microorganism attachment (n=6 per group). A three-way analysis of variance (ANOVA) was conducted, considering the main effects and their interactions (viscosity, LT, and BA). Post-hoc multiple pairwise comparisons were performed. All data were analyzed at a level of significance (P) of 0.05. ResultsLT and BA significantly affected the surface roughness and contact angle of the specimens, depending on resin viscosity (P<.001). Absorbance measurement showed no significant interaction between the three factors (P>.05). However, significant interactions were observed between viscosity and BA (P<.05) and between LT and BA (P<.05). ConclusionsRegardless of the viscosity and LT, discs with a 0-degree BA showed the least roughness. High-viscosity specimens fabricated with a 0-degree BA had the lowest contact angle. Regardless of the LT and viscosity, discs with a 0-degree BA showed the lowest S. oralis attachment. Attachment of C. albicans was the least on the disk with 50 μm LT, irrespective of the viscosity. Clinical significanceClinicians should consider the effects of LT and BA on surface roughness, contact angle, and microbial adhesion of DLP-generated dentures, which can differ depending on resin viscosity. A 50 μm LT and 0-degree BA can be used with a high-viscosity resin to fabricate denture bases with less microbial adhesion.

Evaluation and Comparison of Impact Strength and Transverse Strength of Heat Polymerized Polymethylmethacrylate (PMMA) Denture Base Resin Repaired Using Heat Polymerizied PMMA Denture Base Resin, Auto-Polymerized PMMA Resin and A New Light Polymerizied Denture Resin: An In Vitro Study.

Repaired denture prosthesisdemands adequate transverse and impact strength. A new repairdenture base resin- "Lukafix" require to fulfil these criteria. This study evaluates and compares the transverse and impact strength of heat polymerizing, auto polymerizing and LUKAfix denture resin. 20 specimens were control(without repair), and other were test specimens which were fractured and repaired with heat polymerized PMMA resin, chemically polymerized PMMA resin and LUKAfix light polymerizing denture resin. Each group wasdivided in two subgroups. Subgroup A was subjected to transverse strength test and subgroup B to impact strength test. One way ANOVA was used to identify the mean difference among the four groups. Post-Hoc-Bonferroni was done to observe the difference between the groups. Maximum transverse strength was observed in specimens repaired with heat polymerized (48.33 ± 9.19) and least in LUKAfix denture resin (6.56 ± 1.15). Also, impact strength was maximum for heat polymerized (3.64 ± 0.41) followed by LUKAfix denture resin (2.34 ± 0.44). Repair with LUKAfix denture resin resulted inferior transverse and impact strength as compared to heat polymerized PMMA resin.

A Comparison of the Wetting Ability of Three Artificial Saliva Substitutes on Heat-Cured Denture Base Resin - An In vitro Study.

Salivary substitutes are gaining popularity these days because of the increase in patients with dry mouth. These substitutes must satisfy certain criteria to fulfill the patient's needs. One of these is wettability. One hundred fifty rectangular specimens of heat-cured denture base acrylic resin were prepared. A drop of test liquids (human saliva, distilled water, aqwet, saleva, and wet mouth) was placed over the test specimen and right and left contact angles were measured using optical contact angle machine. All test liquids performed better than distilled water. Human saliva has the least contact angle followed by aqwet. Carboxymethyl cellulose base aqwet saliva substitute was found to be best having similar contact angle values to human saliva.

Modulus of Elasticity of Different Resin Denture Base Materials: A Comparative Study

Modulus of Elasticity of Different Resin Denture Base Materials: A Comparative Study

Comparison of shear bond strength between hard relining material and 3D-printing denture base resin containing silica micro-gel

Comparison of shear bond strength between hard relining material and 3D-printing denture base resin containing silica micro-gel