Effect of coffee thermocycling on the surface roughness and stainability of denture base materials with different chemical compositions manufactured with additive and subtractive technologies.

OBJECTIVE: To evaluate the effect of coffee thermocycling (CTC) on the surface roughness (Ra ) and stainability of denture base materials with different chemical compositions fabricated by using additive and subtractive manufacturing. MATERIALS AND METHODS: Disk-shaped specimens were additively (FREEPRINT denture, AM) or subtractively (G-CAM, GSM and M-PM, SM) fabricated from three pink denture base materials in different chemical compositions (n = 10). Ra was measured before and after polishing, while color coordinates were measured after polishing. Specimens were subjected to CTC (5000 cycles) and measurements were repeated. Color differences (ΔE00 ) after CTC were calculated. Ra among different time intervals within materials was evaluated by using repeated measures analysis of variance (ANOVA), while 1-way ANOVA was used to evaluate the Ra of different materials within each time interval and the ΔE00 values. Color coordinates within each material were compared by using paired samples t-tests (α = 0.05). RESULTS: Ra before polishing was the highest for all materials (p < 0.001), while SM had its lowest Ra after CTC and AM had its lowest Ra after polishing (p ≤ 0.008). Before polishing, AM had the highest Ra among the materials (p < 0.001). After polishing, SM had higher Ra than AM (p < 0.001). After CTC, GSM had the lowest Ra (p ≤ 0.048). SM had the lowest (p ≤ 0.031) and AM had the highest (p < 0.001) ΔE00 . CTC decreased the a* and b* values of SM and AM (p ≤ 0.017), and increased the L* values of AM (p < 0.001). CONCLUSIONS: Polishing significantly reduced the surface roughness of all materials. CTC did not increase the surface roughness of materials above the clinically acceptable threshold. Only AM had perceptible color change when previously reported threshold values for denture base materials were considered. CLINICAL SIGNIFICANCE: Tested denture base materials may have similar surface stability after coffee thermocycling. However, subtractively manufactured denture base materials may have improved color stability when subjected to long-term coffee consumption.

Effect of Tea Tree Oil Addition to Denture Liners Against Candida albicans and Bond Strength to Acrylic Denture Bases.

PURPOSE: To evaluate the effect of adding tea tree oil to denture liners on Candida albicans and bond strength to the acrylic denture base. MATERIALS AND METHODS: Disc-shaped specimens were fabricated from silicone-based resilient liner (Tokuyama, Molloplast), acrylic-based hard liner (GC Reline), and acrylic-based soft liner (Visco-gel). Tea tree oil (TTO) was incorporated into the liners at varying concentrations (0% [control], 2%, 5%, 8%). C albicans were counted by viable colony count, and optical density (OD) was measured with a spectrophotometer. The tensile strength to heat polymerized acrylic denture base was measured in a universal testing machine. The compliance of the data to the distribution of normality was evaluated using the Shapiro Wilk test. Two-way ANOVA, Bonferroni correction, and paired sample t test were performed (α = .05). RESULTS: The addition of TTO into liners provided a significant decrease in the OD values (P < .001). The control groups of the liners presented the highest colony counts, whereas increasing TTO decreased the results (P < .01). According to tensile bond strength test, 8% TTO addition resulted in a significant decrease for Tokuyama (P < .01) and Molloplast liners (P < .05), while 2% TTO resulted in significance for GC Reline (P < .001). CONCLUSIONS: Denture liners containing increasing percentages of TTO presented lower amounts of C albicans colonies and decreased bond strength to the denture bases. When using TTO for its antifungal properties, the amount added should be carefully selected because the tensile bond strength may be affected.

Impact of effervescent denture cleaning tablets on color and surface characteristics of additively manufactured and hand-cast splint materials.

OBJECTIVES: This study is to evaluate the color stability, surface roughness, and hardness of additively manufactured and hand-cast splint materials after a 6-month commercially available denture cleaning tablet immersion simulation. MATERIALS AND METHODS: Disc-shaped additively manufactured and hand-cast auto polymerizing acrylic resin specimens were prepared (N = 40 each). All specimens were exposed to coffee solution totally 2 days. Thereafter, all specimens were immersed into three different effervescent solutions that simulated 6 months of clinical use. The total color change (ΔE*ab), surface roughness (Ra), and Vickers hardness (Vh) were measured at baseline and after immersion protocols. A two-way ANOVA and Bonferroni's post hoc test were used for color change. The dependent t-test and ANOVA were used for roughness and hardness evaluation. RESULTS: Additively manufactured splint materials were more affected by coffee immersion. It was observed that all denture cleaning tablets induced a noticeable alteration in color of the specimens (p < 0.05). Roughness and hardness measurement changes after solution immersions were statistically significant for both splint groups (p < 0.05). On the other hand, distilled water and denture cleaning tablets created similar roughness and hardness measurements at baseline and after immersion. CONCLUSIONS: After 6 months use of tested cleaning tables, the color stability, surface roughness, and hardness of both groups were affected. The evaluation of the surface properties of splint materials could be recommended to the dentists in periodic controls during splint treatments. CLINICAL RELEVANCE: The use effervescent denture cleaning tablets altered the surface characteristics of tested splint materials over time with nonsignificant difference between each other. After 6 months, awareness should be raised about surface characteristics of splint materials.

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

STATEMENT OF PROBLEM: Studies on the mechanical, optical, and surface properties of 3-dimensionally (3D) printed denture base materials are scarce, and those available have reported conflicting results. PURPOSE: The 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 METHODS: A 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). RESULTS: The 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). CONCLUSIONS: The 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.

Anti-fungal efficacy of Miswak Extract (Salvadora Persica) and commercial cleaner against Candida albicans on heat cured polymethylmethacrylate denture base.

AIM: The aim of the study was to compare the antifungal efficacy between commercial cleaner (Corega) and Miswak extract (Salvadora persica) against Candida albicans on heat cured Polymethyl methacrylate (PMMA) acrylic denture base resin. MATERIALS AND METHODS: Forty-eight samples of heat cured PMMA acrylic denture base resin were fabircated in the study. The sterile acrylic resin specimens were immersed in standardized cell suspension of Candida albicans and incubated for 60 min at 370°C for cell adhesion and 2 h at 370°C for biofilm formation. After 24 h biofilm was evaluated by cell viability (CFUs) on SDA and cell counting of Candida albicans under light microscope at 400× magnification. The fungicidal effect of commercial cleaner and Miswak extract on Candida albicans biofilm was then evaluated by colony-forming units on SDA and cell counting under light microscope at 400× magnification. RESULTS: Screening test agar disk-diffusion assay showed mean inhibitory zone of 3 mm for commercial cleaner as compared to Miswak extract, which showed mean inhibitory zone of 2 and 1 mm for different concentrations. Broth microdilution method showed 31 mg/ml MIC and 62.5 mg/ml Minimal Fungicidal Concentration (MFC) values for commercial cleaner as compared to Miswak extract that showed 125 mg/ml MIC and 250 mg/ml MFC values against Candida albicans. A significant difference (p < 0.05) was observed between pre and post treatment of both commercial cleaner and Miswak extract, for CFUs and cell count for Candida albicans. CONCLUSION: Commercial denture cleaner (Corega) showed better antifungal (C albicans) activity than Miswak extract (Salvadora persica) on heat cured PMMA acrylic denture base resin.

Comparison of antifungal efficacy of commercially available denture cleanser and the extract of Turbinaria conoides seaweed against Candida albicans adherent to acrylic denture base resin: An in vitro study.

Aim: One of the main factors responsible for the development of Candida albicans on the surface of denture is improper maintenance of dentures. Denture hygiene can be achieved by regular cleansing of dentures using an appropriate denture cleanser. The aim of the study is to evaluate the antifungal efficacy of commercially available denture cleanser and the extract of Turbinaria conoides seaweed against C. albicans adherent to the surface of denture base resin. Settings and Design: This was an in vitro experimental study. Materials and Methods: Twenty-four Acrylic resin samples of dimension 10-mm radius and 2-mm thickness was randomly divided into two groups. The denture base resin was coated with C. albicans. The colonies present on the surface of each denture base resin were evaluated by serial dilution method. Group A was treated with commercially available denture cleanser and Group B was treated with extract of seaweed T. conoides. The colonies were then evaluated using serial dilution. Statistical Analysis Used: The colony count values obtained by serial dilution were tabulated. These values were statistically analysed using t-test. Results: Reduction of colony count is more in T. conoides than commercially available Fittydent; the difference was statistically significant with a mean difference of 65 at dilution 10-2 and 29.25 at dilution 10-3 using t-test with P < 0.001. Conclusion: Within the limitations of this in vitro study, it was proved that the extract of T. conoides seaweed and commercially available denture cleanser Fittydent was effective in reducing the colony count of C. albicans. T. conoides seaweed is statistically significant than commercially available Fittydent.

Determining growth inhibition of Candida albicans biofilm on denture materials after application of an organoselenium-containing dental sealant.

STATEMENT OF PROBLEM: Denture stomatitis is a chronic inflammatory condition caused by the formation of Candida albicans biofilm on denture bases. It is associated with aggravating intraoral pain, itching, and burning sensations. It can also potentiate cardiovascular diseases and aspiration pneumonia. The problem has thus far eluded efficient, toxic-free, and cost-effective solutions. PURPOSE: The purpose of this in vitro study was to investigate the effectiveness of organoselenium to inhibit the formation of C. albicans biofilm on the surface of acrylic resin denture base materials when it is either incorporated into the acrylic resin material or coated on the denture surface as a light-polymerized surface sealant. MATERIAL AND METHODS: Sixty heat-polymerized polymethyl methacrylate disks were fabricated and assigned to 4 groups (n=15): disks coated with a light-polymerized organoselenium-containing enamel surface sealant (DenteShield), disks impregnated with 0.5% organoselenium (0.5% selenium), disks impregnated with 1% organoselenium (1% selenium), and disks without organoselenium (control). C. albicans biofilm was grown on each disk which had been placed in a well of the microtiter plate containing 1-mL brain heart infusion broth inoculated with C. albicans. The plates were incubated aerobically at 37 °C for 48 hours. A confocal laser scanning microscope was used to determine the biofilm thickness, biomass, and live/dead cell ratio. Biofilm morphology was examined with scanning electron microscopy, whereas microbial viability was quantified by the spread plate method. The data were analyzed by using ANOVA and Tukey-Kramer multiple comparisons (α=.05). RESULTS: The microbial viability, biofilm thickness, biofilm biomass, and live/dead cell ratio were lower (P<.001) on disks in the test groups (DenteShield, 0.5% selenium, 1% selenium) when compared with the control group, with these variables being lowest in the 0.5% selenium and 1% selenium groups. The 0.5% selenium and 1% selenium groups did not differ significantly from each other in any of the variables (P>.05). Scanning electron microscope images showed inhibition of both biofilm growth and yeast to hyphae transition in the DenteShield, 0.5% selenium, and 1% selenium groups, with visible disruption of the biofilm morphology. CONCLUSIONS: The present study demonstrated that organoselenium, whether incorporated into or coated on the surface of an acrylic resin denture base material, has the potential to inhibit Candida albicans biofilm growth on denture surfaces and as such can be clinically useful for the prevention of denture stomatitis.

Antifungal Effects of Herbal Extracts and Fluconazole on Heat-polymerized Acrylic Denture Base Resin as Denture Cleanser: An In Vitro Study.

AIM: The study aimed to investigate the antifungal effects of herbal extracts and fluconazole on heat-polymerized acrylic denture base resin as a denture cleanser. MATERIALS AND METHODS: Several essential oils, such as origanum oil and grape seed oil and commercially available antifungal agent fluconazole were used as denture cleansers and their antifungal efficacy was evaluated using a spectrophotometer. Overall, 68 samples were obtained and were divided into four groups, each containing 17 samples. These samples were immersed in Sabouraud dextrose broth consisting of Candida albicans for 16 hours and later in these antifungal solutions for 8 hours and their antifungal efficacy was measured. Data were subjected to an ANOVA test. RESULTS: Among the study groups origanum oil showed the maximum antifungal activity with a mean optical density at 0.072 ± 0.014 followed by fluconazole (0.094 ± 0.155), and least by grape seed oil (0.190 ± 0.071). CONCLUSION: Results of this in vitro study showed that origanum oil was more effective than commercially available antifungal agents, and among the tested groups oregano oil was a potential agent in lowering the C. albicans colony. CLINICAL SIGNIFICANCE: Origanum oil, being a herbal product, can be considered as a denture cleanser and also be used as an effective alternative to commercially available antifungal agents without any side effects.

Evaluation of flexural strength and antibacterial effect of orthodontic acrylic resins containing Galla chinensis extract

ABSTRACT Objective: To evaluate different concentrations of Galla chinensis extract (GCE) added to poly(methyl methacrylate) (PMMA), which is widely used for fabrication of removable orthodontic appliances, regarding the effectiveness of this herbal extract on antimicrobial effect and flexural strength of PMMA. Methods: Acrylic resin samples containing 0.4%, 0.8% and 1.6% GCE were prepared. Flexural strength was investigated via three-point flexural strength test for the 15 acrylic resin blocks of each concentration. Disk diffusion test was used to evaluate antibacterial effects of incorporating the same concentrations of GCE into acrylic resin. All these three groups were compared with the control group, with no added GCE, regarding flexural strength and antibacterial properties. Results: Comparison of flexural strength between the three study groups and the control group showed significant differences between the groups (P=0.018). However, there was no significant difference between the groups containing GCE. There were significant differences in antimicrobial activity between the four groups (P=0.026). Conclusion: Within the limitations of this study, it is suggested that incorporation of GCE into PMMA would be beneficial for antimicrobial activity and flexural strength of PMMA, but further studies on other physical properties and antimicrobial effects on other bacterial strain would be beneficial prior to clinical investigations.

RESUMO Objetivo: Avaliar se diferentes concentrações de extrato de Galla chinensis (EGC) adicionado ao polimetilmetacrilato (PMMA), que é amplamente utilizado para a fabricação de aparelhos ortodônticos removíveis, interferem no efeito antimicrobiano desse extrato e na resistência à flexão do PMMA. Métodos: Foram preparadas amostras de resina acrílica com concentrações de 0,4%, 0,8% e 1,6% de EGC. Para a avaliação da resistência à flexão, utilizou-se o teste de flexão em três pontos para as 15 amostras de resina em cada concentração. O teste de disco-difusão foi utilizado para avaliar os efeitos antibacterianos da incorporação das mesmas concentrações de EGC na resina acrílica. Esses três grupos foram comparados ao grupo controle, sem adição do EGC, em relação à resistência à flexão e quanto às propriedades antimicrobianas. Resultados: As comparações dos três grupos com o grupo controle mostraram diferenças significativas (p=0,018) para a resistência à flexão. Entretanto, não houve diferença significativa entre os grupos contendo EGC. Foram encontradas diferenças significativas na atividade antimicrobiana entre os quatro grupos (p=0,026). Conclusão: Dentro das limitações desse estudo, parece que a incorporação de EGC no PMMA seria benéfica para a atividade antimicrobiana e a resistência à flexão do PMMA. Porém, estudos adicionais sobre outras propriedades físicas e sobre os efeitos antimicrobianos contra diferentes cepas de bactérias seriam interessantes antes de se fazer pesquisas clínicas.

An In Vitro Assessment of Surface Roughness, Tensile Bond Strength and Antifungal Activity of Grape Seed Extract-modified Soft Liner.

AIM: This study was conducted to evaluate the grape seed extract (GSE)-modified soft liner regarding surface roughness, tensile bond strength to the denture base material, and the antifungal activity. MATERIALS AND METHODS: The GSE powder was blended with the soft liner powder in ratios of 5 and 10% w/w, and three groups were employed: I, control; II, 5% w/w GSE-modified soft liner; III, 10% w/w GSE-modified soft liner. Evaluation parameters included surface roughness, tensile bond strength to the denture base material, and the antifungal activity. Changes in surface topography were evaluated by scanning electron microscopy. The statistical analysis was performed using the one-way ANOVA followed by the Tukey's test (α = 0.05). RESULTS: The 5% w/w GSE-modified soft liner showed a significant increase in surface roughness, while both ratios (5 and 10% w/w) of the modified-soft liner exhibited significant increase in tensile bond strength and antifungal activity (p < 0.05). CONCLUSION: The GSE of 10% w/w considerably enhanced the antifungal activity and tensile bond strength of the modified soft liner to the denture base material without compromising its surface roughness. CLINICAL SIGNIFICANCE: The 10% w/w GSE-modified soft liner may be a promising formulation with antifungal activity. It could inhibit fungal adherence and development of fungi-induced lesions or exacerbation of existing ones.

Antibiofilm efficacy of tea tree oil and of its main component terpinen-4-ol against Candida albicans.

Candida infection is an important cause of morbidity and mortality in immunocompromised patients. The increase in its incidence has been associated with resistance to antimicrobial therapy and biofilm formation. The aim of this study was to evaluate the efficacy of tea tree oil (TTO) and its main component - terpinen-4-ol - against resistant Candida albicans strains (genotypes A and B) identified by molecular typing and against C. albicans ATCC 90028 and SC 5314 reference strains in planktonic and biofilm cultures. The minimum inhibitory concentration, minimum fungicidal concentration, and rate of biofilm development were used to evaluate antifungal activity. Results were obtained from analysis of the biofilm using the cell proliferation assay 2,3-Bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) and confocal laser scanning microscopy (CLSM). Terpinen-4-ol and TTO inhibited C. albicans growth. CLSM confirmed that 17.92 mg/mL of TTO and 8.86 mg/mL of terpinen-4-ol applied for 60 s (rinse simulation) interfered with biofilm formation. Hence, this in vitro study revealed that natural substances such as TTO and terpinen-4-ol present promising results for the treatment of oral candidiasis.

Effect of staining and denture cleaning on color stability of differently polymerized denture base acrylic resins.

BACKGROUND: Denture hygiene is an important factor to remove dental plaque and discoloration, to provide optimal oral health, and to prevent denture stomatitis. AIM: The purpose of this study was to evaluate the effect of coffee staining and denture cleaner on the color stability of two differently polymerized (heat and microwave) denture acrylic resin in vitro. MATERIALS AND METHODS: Two commonly used denture base acrylic resins and effervesecnt tablet form denture cleaner were used in this study. Disc-shaped specimens from each acrylic resin were polymerized according to the manufacturer's instructions (n = 7). Color values were recorded before and after immersion in distilled water (I), denture cleaner (II), coffee (III), and coffee + denture cleaner (IV) with a tristimulus colorimeter using CIEDE2000 color difference formula. Two-way analysis of variance (ANOVA) and Fisher's least significant difference tests were used for multiple comparisons at a 95% confidence level (P < 0.05). Surface topography of the acrylic resin denture base specimens before and after immersion were taken under 500 × magnification. RESULTS: The two-way ANOVA revealed significant interactions between denture base resins and solutions (P < 0.001). Immersion in denture cleaner and coffee solution caused significant color changes in acrylic resin denture bases. CONCLUSION: Heat- and microwave-polymerized acrylic denture base resins can show different color stability. Immersion in coffee and denture cleaner solutions can cause noticeable color changes.

Evaluation of flexural strength and antibacterial effect of orthodontic acrylic resins containing Galla chinensis extract.

OBJECTIVE: To evaluate different concentrations of Galla chinensis extract (GCE) added to poly(methyl methacrylate) (PMMA), which is widely used for fabrication of removable orthodontic appliances, regarding the effectiveness of this herbal extract on antimicrobial effect and flexural strength of PMMA. METHODS: Acrylic resin samples containing 0.4%, 0.8% and 1.6% GCE were prepared. Flexural strength was investigated via three-point flexural strength test for the 15 acrylic resin blocks of each concentration. Disk diffusion test was used to evaluate antibacterial effects of incorporating the same concentrations of GCE into acrylic resin. All these three groups were compared with the control group, with no added GCE, regarding flexural strength and antibacterial properties. RESULTS: Comparison of flexural strength between the three study groups and the control group showed significant differences between the groups (P=0.018). However, there was no significant difference between the groups containing GCE. There were significant differences in antimicrobial activity between the four groups (P=0.026). CONCLUSION: Within the limitations of this study, it is suggested that incorporation of GCE into PMMA would be beneficial for antimicrobial activity and flexural strength of PMMA, but further studies on other physical properties and antimicrobial effects on other bacterial strain would be beneficial prior to clinical investigations.

Antibiofilm efficacy of tea tree oil and of its main component terpinen-4-ol against Candida albicans

Abstract Candida infection is an important cause of morbidity and mortality in immunocompromised patients. The increase in its incidence has been associated with resistance to antimicrobial therapy and biofilm formation. The aim of this study was to evaluate the efficacy of tea tree oil (TTO) and its main component - terpinen-4-ol - against resistant Candida albicans strains (genotypes A and B) identified by molecular typing and against C. albicans ATCC 90028 and SC 5314 reference strains in planktonic and biofilm cultures. The minimum inhibitory concentration, minimum fungicidal concentration, and rate of biofilm development were used to evaluate antifungal activity. Results were obtained from analysis of the biofilm using the cell proliferation assay 2,3-Bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) and confocal laser scanning microscopy (CLSM). Terpinen-4-ol and TTO inhibited C. albicans growth. CLSM confirmed that 17.92 mg/mL of TTO and 8.86 mg/mL of terpinen-4-ol applied for 60 s (rinse simulation) interfered with biofilm formation. Hence, this in vitro study revealed that natural substances such as TTO and terpinen-4-ol present promising results for the treatment of oral candidiasis.

Effect of Commonly Consumed Beverages on Color Stability of Polymethyl Methacrylate Denture Base Material.

Color change of prosthodontic materials may result in patient dissatisfaction and additional expenses for replacement. This study aimed to determine the effect of daily-consumed beverages (tea, coffee, and Pepsi®) on the color stability of two types of heat-cured acrylic resin denture base materials (Hiflex-H and DPI® Heat Cure). A total of 136 disc samples were prepared as per manufacturer instructions and divided into two main groups of 68 discs of each type (20 mm ± 0.1 mm in diameter and 3 mm ± 0.1 mm in thickness), according to the acrylic resins, and stored in distilled water for 24 hours. Each group was subdivided into four groups according to the three beverages types and distilled water (as a control). Specimens were scanned (computer analysis) three times after consumption of the beverage: 0 day (T0), 15 days (T1), and 30 days (T2). The International Commission on Illumination was used to determine the mean color change (ΔE). The most color change was apparent with tea after 30 days (ΔE = 39.21) when compared to specimens stored in distilled water (ΔE = 1.43). DPI Heat Cure acrylic resin showed more color change compared to Hiflex-H acrylic resin. When computing color change (ΔE) to NBS (National Bureau of Standards), appreciable to very much change in color was apparent with the three staining beverages compared to slight and noticeable color change with distilled water. By increasing the time of the experiment, significant increase in the mean color was observed. Tea immersion showed the greatest color changes (very much change in color, per NBS), followed by Pepsi and coffee. Increasing the immersion period increased the staining result.

Optical properties and surface roughness of prepolymerized poly(methyl methacrylate) denture base materials.

STATEMENT OF PROBLEM: Studies of the color stability, relative translucency, and surface roughness of newly introduced computer-assisted design and computer-assisted manufacturing (CAD-CAM) prepolymerized poly(methyl methacrylate) (PMMA) denture base materials are lacking. PURPOSE: The purpose of this in vitro study was to evaluate the color stability, relative translucency, and surface roughness of conventional and different prepolymerized CAD-CAM PMMA denture base materials after coffee thermocycling (CTC). MATERIAL AND METHODS: Six disk-shaped specimens (10×2 mm) were prepared from 3 different brands of prepolymerized CAD-CAM PMMA and a conventional heat-polymerized PMMA denture base material (N=24). Specimens were polished conventionally in 2 stages. The specimens were subjected to 5000 coffee thermocycles. The surface roughness (Ra) of each specimen was measured 3 times before and after CTC, using a contact profilometer, and the mean roughness (Ra) values were calculated. The color coordinates of the specimens were determined by using a noncontact spectroradiometer, and color differences and relative translucency parameter (RTP) values were calculated by using CIEDE2000 color difference and RTPCIEDE2000 formulas. ANOVA was used to analyze surface roughness values, CIEDE2000 color differences, and RTP values (α=.05). RESULTS: CTC did not change the color of the tested materials. However, with regard to relative translucency, 2-way ANOVA revealed a significant interaction between the material and CTC (P=.011). Also, although CTC increased the surface roughness of all tested materials (P=.031), Ra values were lower than the plaque accumulation threshold of Ra=0.2 µm. CONCLUSIONS: Mean color changes in all materials were clinically imperceptible after 5000 coffee thermocycles. One tested material had significantly lower relative translucency than other materials before and after CTC. The surface roughness values of all tested denture base materials were below the plaque accumulation threshold.

Effect of Henna Addition on the Surface Roughness and Hardness of Polymethylmethacrylate Denture Base Material: An in vitro Study.

AIM: This study aimed to evaluate the effect of the addition of various henna-which can have antifungal properties-on the surface roughness and hardness of polymethylmethacrylate (PMMA) denture base material. MATERIALS AND METHODS: A total of 99 rectangular-shaped (10 × 20 × 3 mm3) specimens were prepared from heat-cured acrylic resin and divided into one control group without the addition of henna and five test groups, which were prepared by adding Yamanihenna powder to polymer at concentrations of 1, 2.5, 5, 7.5, and 10 wt%. The polymer was added to the monomer, mixed, packed, and processed using the conventional water bath method. After processing, specimens were finished and polished, then kept in distilled water for 48 ± 2 hours. A profilom-eter and Vickers hardness tester were used to measure surface roughness and hardness respectively. Statistical data analysis was conducted via Statistical Package for the Social Sciences (SPSS) version 20.0 (IBM, USA). The independent sample t-test was used and p ≤ 0.05 was considered statistically significant. RESULTS: The addition of henna at varying concentrations significantly increased the surface roughness values (p ≤ 0.01) while decreasing hardness (p ≤ 0.0001). The most favorable addition value was 1% henna between all henna groups. CONCLUSION: The addition of henna to the acrylic resin may negatively affect the surface properties of PMMA acrylic denture base. CLINICAL SIGNIFICANCE: Antimicrobial denture with minimum deterioration effects on its physical properties could be achieved with henna addition to denture base material in low concentration. However, 1% henna showed the best results between the henna groups as regards roughness and hardness values.

Development of antibacterial denture cleaner for brushing containing tea tree and lemongrass essential oils.

We evaluated effectiveness of tea tree oil (TO) and lemongrass oil (LO) for removal of Candida biofilm from denture base resin and their influence on that surface. Biofilm of C. albicans was formed on resins, and immersed in various concentrations of each oil and distilled water (DW). The biofilm removal effect was determined by incubating specimens in RPMI medium containing Alamar blue (AB) and measuring absorbance. Wear test was also conducted, and surface condition of resins was determined using laser scanning microscope and digital microscope. Specimens immersed in the TO and LO solutions tended to have a lower AB value at higher concentrations and longer soaking times. Use of these agents resulted in less surface roughness as compared to DW. Our results suggest that TO and LO were valid to remove biofilm attached to resin with lower levels of abrasion, and these are effective for use in denture cleaner.

Effectiveness of non-fluoride and fluoride dentifrices for denture hygiene.

OBJECTIVE: To compare the effectiveness of commonly used herbal/non-fluoride with fluoride dentifrices in order to eliminate pathogenic oral microorganisms from denture base material. MATERIALS AND METHODS: Heat-polymerized acrylic resin specimens (n = 288) were divided into three groups and each group inoculated with three various microorganisms (n = 96 for each) Candida albicans, Staphylococcus aureus and Pseudomonas aeruginosa (P. aeruginosa). Contaminated specimens were randomly assigned to the application of six herbal/non-fluoride and three fluoride dentifrices. These specimens were divided into two groups: negative and positive control (n = 3 for each). All acrylic specimens were incubated at 37 °C for 24 h for samples inoculated with bacterial strains and 37 °C for 48 h for samples inoculated with yeast strains. After the incubation period, all brain-heart infusion broths that contained disinfectant acrylic specimens were cultured on 5% sheep blood agar for bacterial counts and Sabouraud dextrose agar for yeast counts. The number of colony-forming units per millilitre (CFU/mL) were calculated. The results were analysed by Mann-Whitney U and Kruskal-Wallis tests (p = .05). RESULTS: Both herbal/non-fluoride and fluoride dentifrices were effective against Candida albicans. However, fluoride dentifrices were comparatively better than the herbal/non-fluoride dentifrices against Staphylococcus aureus and P. aeruginosa. CONCLUSIONS: Herbal dentifrices could be used, especially among the elderly who lack a degree of manual dexterity during the rinsing of dentifrice chemicals from their dentures.

Equisetum giganteum influences the ability of Candida albicans in forming biofilms over the denture acrylic resin surface.

CONTEXT: Equisetum giganteum L. (Equisetaceae) is an endemic plant of Central and South America used in traditional medicine. Natural drugs have been frequently used in the treatment of a myriad of diseases, proving to be an alternative to synthetic chemicals, and have been intensively studied in the prevention of sicknesses, including oral diseases. OBJECTIVE: This study evaluated the in vitro antiadherent activity of E. giganteum extract against Candida albicans biofilms. MATERIALS AND METHODS: Crystal violet and colony-forming units assays were used to quantify the total biofilm biomass and biofilm living cells on a denture base acrylic resin pretreated with hydroethanolic extract of E. giganteum in different concentrations (50, 25, 16, 8, and 4 mg/mL), after 24 h of biofilm development. RESULTS: Equisetum giganteum affected biofilms by reduction of biomass and living cells per area of acrylic specimens. The results revealed reduction of 15-44% of the biofilm mass and reduction of numbers of colony-forming units (CFUs) present in biofilms (79%) compared to the untreated control (CTRL/PBS). At all concentrations, it demonstrated important antiadherent activity on Candida albicans biofilms, the main microbe in denture stomatitis. DISCUSSION AND CONCLUSION: The present findings show that E. giganteum antimicrobial effects may qualify the extract as a promising natural alternative for topical treatment or prevention of denture stomatitis. The usage of drugs made of natural products shows advantages in relation to synthetic drugs on the market, such as lower cost, lower toxicity, and in relation to the occurrence of microbial resistance.