Microbiological Evaluation of Thermoplastic PETG Dental Appliances Related to Surface Characteristics

(1) Background: The adhesion and microbiological behaviour of thermoplastic PETG dental appliance surfaces is governed by roughness parameters. The aim of this research was to evaluate the antibiofilm activity of alkaline peroxide-based disinfectant in Candida albicans biofilms on thermoplastic PETG, related to artificial ageing and surface characteristics, on multiscale levels. (2) Methods: In the present study, two PETG materials were investigated: Crystal® (Bio Art Dental Equipment, Sao Carlos, Brazil), noted as C, and Duran® (Scheu-Dental GmbH, Iserlohn, Germany)-noted as D. Half of the specimens were thermally cycled (TC), resulting in four sample groups, as follows: C, CTC, D, and DTC. Surface roughness was evaluated on different scale topographies. The biofilms were grown on the surfaces. An alkaline peroxide-based disinfectant was used. Statistical analyses were performed. (3) Results: Related to nanoroughness, there are insignificant differences among materials or related to thermocycling. More irregular surfaces are associated with larger grain sizes. After thermocycling, micro-roughness values increase. Disinfectant activity decreases the amount of biofilm developed on the surfaces, significantly in the two groups, but is not correlated to the material and artificial ageing. (4) Conclusion: The impact of surface roughness (Ra) on biofilm constitution is controlled by different scale topographies.

The Effect of Aging on Artificial Saliva at Different pH Values on the Color Stability of New Generation Denture Base Materials

STATEMENT OF PROBLEM

New-generation denture base materials are used successfully in denture fabrication; however, the effect of saliva pH change on the color stability of materials is unknown.

PURPOSE

The purpose of this in vitro study is to evaluate the color stability of new-generation denture base materials after immersion in artificial saliva with different pH values (3,7,14).

MATERIAL AND METHODS

Disc-shaped samples (Ø 10 mm x 2 mm) were prepared from three different denture base materials (1 pre-polymerized polymethylmethacrylate [PMMA], 1 graphene-reinforced PMMA, and heat-cure polymethyl methacrylate resin) (n=10). After polishing, color coordinates were measured using a PCE-CSM 5 colorimeter programmed in the CIE system (L* a* b*). The samples were kept in artificial saliva at different pH values and 37°C for 21 days. At the end of 21 days, color coordinates were measured again. The suitability of the measurements for a normal distribution was examined with the Kolmogro-Smirnov test. Whether color measurements obtained at different pH levels differed according to groups was examined with the Kruskal-Wallis test. The correlation between the CIEDE2000 and CIELab color difference formulas was examined by correlation analysis.

RESULTS

The highest color difference occurred in heat-cure samples at pH 3 (p<0.001). The color difference at different pH values was least observed in pre-polymerized PMMA samples. Significant color differences occurred in the graphene-reinforced pre-polymerized PMMA group at pH 7 (p<0.001).

CONCLUSIONS

It was observed that color differences occurred in all groups. Dentures made of new-generation CAD/CAM PMMA, which are less exposed to color differences, can be recommended for elderly patients with systemic diseases who are frequently exposed to pH changes in the oral cavity.

CLINICAL IMPLICATIONS

Color differences on denture surfaces over time negatively affect aesthetics. Since pH changes cause changes on the prosthesis surface, it may be recommended for these patients to fabricate dentures from new-generation CAD/CAM PMMA resins, which are less deformable.

Different Polymers for the Base of Removable Dentures? Part II: A Narrative Review of the Dynamics of Microbial Plaque Formation on Dentures

This review focuses on the current disparities and gaps in research on the characteristics of the oral ecosystem of denture wearers, making a unique contribution to the literature on this topic. We aimed to synthesize the literature on the state of current knowledge concerning the biological behavior of the different polymers used in prosthetics. Whichever polymer is used in the composition of the prosthetic base (poly methyl methacrylate acrylic (PMMA), polyamide (PA), or polyether ether ketone (PEEK)), the simple presence of a removable prosthesis in the oral cavity can disturb the balance of the oral microbiota. This phenomenon is aggravated by poor oral hygiene, resulting in an increased microbial load coupled with the reduced salivation that is associated with older patients. In 15-70% of patients, this imbalance leads to the appearance of inflammation under the prosthesis (denture stomatitis, DS). DS is dependent on the equilibrium-as well as on the reciprocal, fragile, and constantly dynamic conditions-between the host and the microbiome in the oral cavity. Several local and general parameters contribute to this balance. Locally, the formation of microbial plaque on dentures (DMP) depends on the phenomena of adhesion, aggregation, and accumulation of microorganisms. To limit DMP, apart from oral and lifestyle hygiene, the prosthesis must be polished and regularly immersed in a disinfectant bath. It can also be covered with an insulating coating. In the long term, relining and maintenance of the prosthesis must also be established to control microbial proliferation. On the other hand, several general conditions specific to the host (aging; heredity; allergies; diseases such as diabetes mellitus or cardiovascular, respiratory, or digestive diseases; and immunodeficiencies) can make the management of DS difficult. Thus, the second part of this review addresses the complexity of the management of DMP depending on the polymer used. The methodology followed in this review comprised the formulation of a search strategy, definition of the inclusion and exclusion criteria, and selection of studies for analysis. The PubMed database was searched independently for pertinent studies. A total of 213 titles were retrieved from the electronic databases, and after applying the exclusion criteria, we selected 84 articles on the possible microbial interactions between the prosthesis and the oral environment, with a particular emphasis on Candida albicans.

Effect of Hygiene Protocols on the Mechanical and Physical Properties of Two 3D-Printed Denture Resins Characterized by Extrinsic Pigmentation as Well as the Mixed Biofilm Formed on the Surface

To assess the effect of hygiene protocols and time on the physical-mechanical properties and colony-forming units (CFU) of Candida albicans, Staphylococcus aureus, and Streptococcus mutans on 3D-printed denture resins (SmartPrint and Yller) with extrinsic pigmentation compared to conventional resin (CR). The protocols were evaluated: brushing (B), brushing and immersion in water (W), 0.25% sodium hypochlorite (SH), and 0.15% triclosan (T), simulating 0, 1, 3, and 5 years. The data were analyzed by ANOVA with repeated measurements, ANOVA (Three-way) and Tukey's post-test, generalized linear model with Bonferroni adjustment, and ANOVA (Two-way) and Tukey's post-test (α = 0.05). The protocols influenced color (p = 0.036) and Knoop hardness (p < 0.001). Surface roughness was influenced by protocols/resin (p < 0.001) and time/resin (p = 0.001), and flexural strength by time/protocols (p = 0.014). C. albicans showed interactions with all factors (p = 0.033). Staphylococcus aureus was affected by protocols (p < 0.001). Streptococcus mutans exhibited no count for SH and T (p < 0.001). Yller resin showed more color changes. The 3D-printed resins displayed lower microhardness, increased roughness, and decreased flexural strength compared to CR with all protocols in a simulated period of 5 years. The indication of printed resins should be restricted to less than 3 years.

Effects of two novel denture cleansers on multispecies microbial biofilms, stain removal and the denture surface: an in vitro study

BACKGROUND

The continuously increasing demand for removable denture appliances and the importance of adequate denture cleaning have led to the development of various denture cleansing products. The aim of this study was to evaluate the efficacy of two novel denture cleansing agents (GE and TM) and three commonly available cleansers (0.5% sodium hypochlorite; NaClO, 0.12% chlorhexidine gluconate; CHX, and Polident®; POL) on multispecies microbial biofilm formation, stain removal and physical properties of dentures.

METHODS

The antimicrobial activities of denture cleansing agents were determined against major oral opportunistic pathogens including Streptococcus mutans, Staphylococcus aureus, Escherichia coli and Candida albicans, using time-kill assays. Multispecies microbial biofilms grown on acrylic resins for 72 h were generated to determine the antibiofilm effects of cleansing agents by confocal laser scanning microscopy (CLSM). Evaluations of the tea and coffee stain removal properties and the alterations in the physical properties of dentures were also performed. The toxicity of cleanser residues released from denture acrylics to fibroblast cells was investigated using MTT assay.

RESULTS

All denture cleansing agents tested could effectively kill oral bacteria and Candida albicans. Furthermore, after immersion for more than 3 h, the cleansers Polident®, GE and TM could efficiently penetrate and inhibit multispecies denture biofilms with effects similar to 10 min of immersion in 0.5% NaClO. However, immersion in 0.12% CHX for 20 min showed less antibiofilm activity. The NaClO solution had the highest efficacy for removing stains from the artificial teeth. Conversely, the CHX solution enhanced tea and coffee staining, and the teeth immersed in this solution showed clinically unacceptable colour changes (ΔE > 5.5). However, the colour differences of teeth stained and immersed in POL, GE and TM cleansers were in the clinically acceptable range. There was no significant difference among the POL, GE and TM cleansers in terms of stain removal efficacy. The cleansers GE and TM did not alter the surface roughness and colour of the materials, moreover the residues of both cleansers did not exhibit cytotoxicity.

CONCLUSION

Two novel denture cleansing agents containing natural products, GE and TM exhibited effective antimicrobial activity, antibiofilm and stain removal capabilities without toxicity or disturbance of the physical properties of acrylics.

The effect of different denture cleansing solutions on the retention of polyetheretherketone locator attachments

PURPOSE

Prosthetic cleansing solutions have been reported to cause retention loss in implant locator attachments due to the chemical alterations of these attachments. This study aimed to investigate the effects of different denture cleansing solutions on attachments with different retention values.

MATERIALS AND METHODS

In this study, 160 polyetheretherketone locator attachments were divided into 4 groups according to their attachment retention values (yellow, pink, clear, and violet). Forty attachments from each group were soaked in four different cleansing solutions (n = 10). The attachments from the four groups were immersed in water, sodium hypochlorite, Corega, and Protefix solutions for a period equivalent to 6 months, according to the manufacturer's recommendations. The locator attachments were then subjected to testing using a universal testing machine. Maximum load to dislodgement according to different solutions was evaluated by one-way ANOVA test. Statistical significance was set at p < 0.05.

RESULTS

The effect of denture cleansing solutions on the retentive values of attachments was statistically significant (p < 0.001). Among all cleansing solutions, the highest retention value was found in the violet attachments, and the lowest retention value was found in the yellow attachments. The lowest retention value (0.72 ± 0.05 MPa) was observed when the yellow attachments were immersed in Protefix solution, and the highest retention value (1.96 ± 0.15 MPa) was observed when the violet attachments were immersed in the Corega solution.

CONCLUSION

For different colored attachments, different cleansing solutions can be suggested to patients.

Efficacy of antimicrobial photodynamic therapy in disinfection of Candida biofilms on acrylic dentures: A systematic review

BACKGROUND

The aim of this systematic review was to critically analyze and summarize the currently available scientific evidence concerning antifungal efficacy of aPDT against Candida on acrylic surface.

METHODS

The focused question was: '"Is aPDT effective in minimizing the counts of Candida on acrylic dentures". A literature search was conducted interpedently on the following electronic research databases: PubMED/MEDLINE, Cochrane, Google Scholar and Embase. The MeSH terms used were: ((antimicrobial photodynamic therapy) OR (light) OR (laser) OR (photodynamic)) AND ((Candida) OR (denture stomatitis)) AND ((denture) OR (acrylic) OR (polymethylmethacrylate) OR (dental prosthesis)). Data was extracted from the studies and quality assessment was carried out using a modified version of the CONSORT checklist.

RESULTS

Eighteen in-vitro anti-microbial studies and 5 clinical studies were included. Twenty-two studies suggested that aPDT was effective in reducing the Candida count on acrylic dentures and one study did not have a significant effect. 19 out of 23 studies were graded as having 'medium' quality and 4 studies were graded as 'high'. Several photosensitizers, including methylene blue, porphyrin derivatives, toluidine blue-O and others were used. LED was the most popular light source used for photo-activation of the photosensitizers.

CONCLUSION

Within the limitations of this review, aPDT is effective in reducing Candida growth on acrylic dentures and may prove to be clinical effective in preventing or treating denture stomatitis. However, more long-term clinical research is required before its clinical efficacy can be determined.

Denture cleanliness and hygiene: an overview

Dentures are an excellent treatment modality for partial and edentate patients; however, improper denture care and hygiene can result in both decreased longevity of the prosthesis and increased risk of developing dental caries, periodontal disease and oral candidosis. Previously, it has been shown that patients and dental professionals are unaware of the different materials and methods available for optimum denture care and hygiene. This article provides an overview of the key legislation and main commercially available methods for denture cleanliness and hygiene, and serves as a basis for providing tailored denture hygiene for denture wearers.

Patients typically demonstrate poor levels of denture hygiene which impacts oral health.

Denture hygiene instructions comprise mechanical and chemical methods; both should be tailored to the denture wearer.

Denture base and denture teeth materials had different compatibility with different denture cleaning methods.

Evaluation of microhardness in two types of denture bases after using sodium hypochlorite and NatureDent disinfecting agents

Background. Chemical agents, in combination with mechanical methods, play an important role in reducing microbial plaque on denture surfaces. However, these methods might change the mechanical behavior of acrylic resins, including microhardness and surface roughness. This in vitro study investigated the effect of two disinfectants, i.e., water and sodium hypochlorite, on the microhardness of conventional heat-cured and TiO₂ nanoparticle-reinforced acrylic resins. Methods. Sixty acrylic resin specimens were divided into two groups, and the samples in each group were randomly assigned to three subgroups (n=10). Heat-cured specimens and 1 wt% TiO₂ acrylic resin were prepared and immersed in three solutions: water, a solution prepared with NatureDent pills, and 1% sodium hypochlorite for 30, 60, and 90 days. Microhardness tests were performed on each sample at each immersion stage. The data were analyzed using descriptive statistical methods, three-way and one-way ANOVA, repeated-measures t test, and Tukey HSD tests using SPSS 17. P values<0.05 were considered significant. Results. All three independent parameters, including resin, solution, and time, significantly affected microhardness (P<0.05). The microhardness of both specimen types, i.e., conventional heat-cured and TiO₂ nanoparticle-reinforced acrylic resins, immersed for 30, 60, and 90 days, was the highest and lowest in water and hypochlorite solutions, respectively. Regarding 90 days, the microhardness values of conventional heat-cured and TiO₂ nanoparticle-reinforced acrylic resins were 17.050±0.094 and 19.953±0.053 in water, 15.675±0.069 and 18.965±0.037 in hypochlorite, and 16.713±0.122 and 19.39±20.113 in NatureDent solutions, respectively. Conclusion. Disinfecting two types of acrylic resin specimens decreased their microhardness as a function of immersion time for up to 90 days in the three solutions. However, the magnitude of hardness lost was less for TiO₂ nanoparticles-reinforced acrylic resin.

CLEANING OF REMOVABLE DENTAL PROSTHESES - A SYSTEMATIC REVIEW

Objectives The aim of this systematic review was to provide an overview of the scientific evidence available from prospective clinical studies regarding denture hygiene interventions. Therefore, investigations addressing the efficacy of removing microorganisms and biofilms formed on the surface of removable dental prostheses (RDPs) and denture base materials in situ and their impact on the properties of denture base materials, such as color stability, surface roughness, and dimensional stability, were included. Methods A systematic literature search was conducted from June 1975-May 2020 and included articles published in English that have been indexed in the digital archives of PubMed and Cochrane (including PubMed, Embase, ICTRP, CT.gov). A complementary manual search of the initially retrieved studies was conducted. Inclusion criteria comprised prospective clinical trials with a minimum of ten participants investigating (1) approaches and methods to remove biofilms formed on the surface of RDPs and denture base materials in situ and/or (2) the influence of these biofilms on denture base materials. A total of forty-four studies were included in this systematic review, which was registered in the PROSPERO database (CRD42020189649). Results and Conclusions Data gathered from the systematic review indicate that the combined use of chemical and mechanical denture hygiene interventions is significantly more effective than single cleaning approaches. Only limited evidence is available from clinical studies regarding the effect of denture hygiene interventions on the properties of denture base materials.

Complete denture hygiene solutions: antibiofilm activity and effects on physical and mechanical properties of acrylic resin

BACKGROUND

Appropriated denture hygiene is a predictive factor for longevity of rehabilitation treatment and maintenance of the oral mucosal health. Although, disinfectant solutions are commonly used as denture cleansers, the impact of these solutions on acrylic resin-based dentures remain unclear.

OBJECTIVE

To evaluate, in vitro, the antibiofilm activity of complete denture hygiene solutions and their effects on physical and mechanical properties of acrylic resin.

METHODOLOGY

For antibiofilm activity measurement acrylic resin specimens were contaminated with Candida albicans, Candida glabrata and Streptococcus mutans. After biofilm growth, the specimens were assigned to the hygiene solutions: Distilled water (Control); 0.2% Sodium hypochlorite (SH); Efferdent Power Clean Crystals (EPC) and 6.25% Ricinus communis (RC). The viability of microorganisms was evaluated by agar plate counts. In parallel, physical, and mechanical properties of the acrylic resin were evaluated after simulating a 5-year period of daily immersion in the previously mentioned solutions. The changes in surface roughness, color, microhardness, flexural strength, impact strength, sorption and solubility were evaluated. Data were compared by ANOVA followed by the Tukey test or Kruskal-Wallis followed by the Dunn test depending on the distribution (α=0.05).

RESULTS

Regarding antibiofilm action, SH eliminated all microorganisms while EPC and RC exhibited moderate action against S. mutans (p=0.001) and C. glabrata (p<0.001), respectively. Relative to effects on the physical and mechanical properties of the acrylic resin, RC led to higher values of color change (p=0.030), hardness (p<0.001), surface roughness (p=0.006) and flexural strength (p<0.001). Moreover, RC induced the highest values of changes in solubility (p<0.001). EPC promoted greater changes in surface morphology, whereas immersion in SH retained the initial appearance of the acrylic resin surface. All hygiene solutions reduced the impact strength (p<0.05).

CONCLUSION

SH presented the most effective antibiofilm activity. In addition, changes on properties were observed after immersion in RC, which were considered within acceptable limits.

Development of a novel denture care agent with highly active enzyme, arazyme

BACKGROUND

The importance of efficient denture deposit removal and oral hygiene has been further underscored by the continuous increase of denture wearers. Denture hygiene management has also become an important aspect associated with denture-induced stomatitis. This study aims to evaluate the denture cleaning effect of arazyme, the metalloprotease produced from the Serratia proteamaculans HY-3. We performed growth inhibition tests against oral opportunistic pathogens to be used as a potential oral health care agent.

METHODS

The proteolytic activities of arazyme was evaluated over broad ranges of temperature, pH, and denture components compared to those of subtilisin in commercially available denture cleansers. The washing effects of arazyme were also measured by using homogeneously soiled EMPA 105 cottons. To investigate the denture cleaning capability of arazyme, artificially contaminated dentures were treated with arazyme, subtilisin (Everlase 6.0T), and Polident®, respectively. The growth kinetics of Candida albicans, Enterococcus faecalis, Staphylococcus epidermis, and Streptococcus mutans were evaluated in the presence of different concentrations of arazyme to estimate the prevention effects of arazyme against major oral opportunistic pathogens.

RESULTS

Arazyme showed strong proteolytic activities over wide temperature and pH ranges compared with the serine protease of the subtilisin family. Arazyme demonstrated efficient removal and decomposition of artificially contaminated dentures and showed explicit washing effects against soiled cottons. Moreover arazyme inhibited the growth of oral opportunistic pathogens, including C. albicans, E. faecalis, S. epidermis, and S. mutans, with more than 80% inhibition against C. albicans, the major cause of denture stomatitis, with 250 mg/mL arazyme.

CONCLUSIONS

Arazyme shows promise as a biological oral health care agent with effective cleaning and antimicrobial activities and is a potential source for developing novel denture care agents.

Evaluation of quality of life and oral hygiene attitudes of individuals using dental prostheses during the COVID-19 pandemic

STATEMENT OF PROBLEM

The COVID-19 pandemic impacted every area of our lives, including delaying urgent dental care. However, studies evaluating how patients using dental prostheses have been affected by the pandemic are lacking.

PURPOSE

The purpose of this study was to investigate how patients using different types of dental prostheses were being affected by the COVID-19 pandemic.

MATERIAL AND METHODS

A total of 129 randomly selected individuals from among those who had been examined in the same clinic before the COVID-19 outbreak were included in the study. The study participants were divided into 4 groups according to their type of prosthesis: complete dentures, implant-retained removable dentures, tooth-supported fixed partial dentures, and implant-supported fixed partial dentures. The Oral Health Impact Profile (OHIP-14) questionnaire was implemented by telephone interviews with the study participants, who were also asked about their concerns and steps made regarding prosthetic hygiene during the COVID-19 pandemic. Data were evaluated by the Kruskal-Wallis and post hoc Dunn tests, and multivariate logistic regression analysis with forward selection was carried out to identify predictors of the oral health-related quality of life (OHRQoL) status (α=.05).

RESULTS

OHIP-14 total scores did not vary significantly among the groups (P>.05). When the domain scores of OHIP-14 were considered separately, the analysis revealed that the implant-retained removable denture group had significantly poorer functional limitations when compared with the tooth-supported fixed partial denture (P=.005) and implant-supported fixed partial denture (P=.031) groups. The results of the multivariate logistic regression analysis indicated a statistically significant association between OHRQoL during the COVID-19 pandemic and the frequency of tooth or denture cleaning (1 time a day versus less than 1 time a day: P=.011; 2-3 times a day versus less than 1 time a day: P=.032).

CONCLUSIONS

All prosthesis users exhibited increased interest in dental hygiene and an increase in the frequency of prosthesis cleaning during the pandemic. Furthermore, the study determined that the frequency of tooth or denture cleaning was associated with significantly improved OHRQoL during the time of the COVID-19 pandemic. Among the denture groups, those treated with implant-retained removable dentures had the poorest functional limitation in terms of OHRQoL, which can be linked to postponement of routine maintenance appointments. Therefore, providing all patients with scientifically sound information on prosthetic care during a pandemic would be highly beneficial.

Color Stability and Surface Properties of PMMA/ZrO2 Nanocomposite Denture Base Material after Using Denture Cleanser

Objectives

This study aimed to evaluate denture cleanser effects on color stability, surface roughness, and hardness of PMMA denture base resin reinforced with nano-ZrO₂.

Materials and Methods

A total of 420 specimens were fabricated of unreinforced and nano-ZrO₂ reinforced acrylic resin at 2.5% and 5%, resulting in 3 main groups. These groups were further subdivided (n = 10) according to immersion solution (distilled water, Corega, sodium hypochlorite, and Renew) and immersion duration. Surface roughness, hardness, and color were measured at baseline (2 days-T₀) in distilled water and then after 180 and 365 days of immersion (T₁ & T₂) in water or denture cleansing solutions. Data was collected and analyzed using two-way ANOVA followed by Bonferroni post hoc test (α = 0.05).

Results

Surface roughness increased significantly after denture cleanser immersion of unmodified and nano-ZrO₂-modified PMMA materials while hardness decreased (P < 0.001). The denture cleansers significantly affected the color of both PMMA denture bases (P < 0.001). The immersion time in denture cleansers significantly affected all tested properties (P < 0.001). Within denture cleansers, NaOCl showed the highest adverse effects (P < 0.05) while Renew showed the least adverse effects.

Conclusion

Denture cleansers can significantly result in color change and alter the surface roughness and hardness of denture base resin even with ZrO₂ nanoparticles addition. Therefore, they should be carefully used.

Does microwave and hydrogen peroxide disinfection reduce Candida albicans biofilm on polymethyl methacrylate denture surfaces?

STATEMENT OF PROBLEM

Whether the disinfection of polymethyl methacrylate (PMMA) dentures eliminates Candida albicans biofilm is unclear.

PURPOSE

The purpose of this in vitro study was to determine the antimicrobial effect of immersion in hydrogen peroxide (H₂O₂) and subsequent application of microwaves on the formation of C albicans biofilm on the surface of polished and unpolished PMMA disks.

MATERIAL AND METHODS

Polished and unpolished PMMA disks (n=40) were mounted in a Center for Disease Control (CDC) biofilm reactor by adding yeast-dextrose-peptone (YPD) broth inoculated with C albicans in a cell suspension for 24 hours. After this period, the PMMA disks (n=8) were disinfected with 5 different solutions: saline solution, 1% sodium hypochlorite (NaOCl), H₂O₂, H₂O₂ microwaved at 650 W for 3 minutes (H₂O₂/μw), and distilled water microwaved at 650 W for 3 minutes (H₂O/μw). On the polished and unpolished surface of each disk, arbitrary fluorescence units (AFU) were quantified with the live/dead bacterial viability kit (Invitrogen) by using confocal laser scanning microscopy (CLSM) to evaluate 10 different areas of each surface; these were counted as the colony-forming units (CFUs). The mean values were compared by using the Mann-Whitney U test (α=.05).

RESULTS

Polished surfaces disinfected with H₂O₂/μw obtained the lowest viable cells (9.76 AFU) and nonviable cells (12.46 AFU) compared with H₂O/μw and H₂O_2. In the unpolished surface the lowest mean values of viable cells (14.64 AFU) and nonviable cells (12.46 AFU) were obtained for the PMMA disks disinfected with H₂O/μw compared with H₂O₂/μw and H₂O₂. Both polished and unpolished disks showed significant difference (P<.05) compared with the group of PMMA disks immersed in saline solution. No CFUs were detected in the polished or unpolished PMMA disks immersed in H₂O₂/μw or in NaOCl.

CONCLUSIONS

H₂O₂ alone did not eliminate the formation of the biofilm of C albicans; however, in combination with the use of the microwave at 650 W for 3 minutes, the biofilm formation of C albicans on polished surfaces was reduced. The number of AFUs of viable-nonviable cells and CFUs depended on whether the surfaces are polished or unpolished.

Effect of local hygiene protocols on denture-related stomatitis, biofilm, microbial load, and odor: A randomized controlled trial

STATEMENT OF PROBLEM

Denture stomatitis affects complete denture wearers and is frequently treated with antifungals drugs, as well as treating the denture with sodium hypochlorite. Whether the limitations of these treatments can be overcome with local hygiene protocols that do not damage the denture materials or adversely affect the patient is unclear.

PURPOSE

The purpose of this randomized controlled trial was to evaluate the effect of denture hygiene protocols on complete denture wearers with denture stomatitis.

MATERIAL AND METHODS

For this randomized, double-blind controlled clinical trial, 108 participants were assigned to parallel groups: 0.25% sodium hypochlorite (positive control) 0.15% Triclosan, denture cleaning tablets, or denture cleaning tablets plus gingival cleaning tablets. The participants were instructed to brush the dentures and the palate and immerse the denture in the solutions. The outcomes of denture stomatitis remission, biofilm removal, decrease of microbial load (colony-forming units), and odor level of the mouth and denture were measured at baseline and after 10 days. Descriptive analyses were used for sociodemographic characterization of the participants; the Pearson chi-square test was used to compare participant frequency with different degrees of denture stomatitis. The data were not normally distributed (Shapiro-Wilks test) or homogeneous (Levene test). So, the Kruskal-Wallis and Dunn post hoc tests and Wilcoxon test were used to compare the effects of solutions and time on the variables (α=.05).

RESULTS

The frequency of the highest to lowest denture stomatitis scores was significantly different for the 0.15% Triclosan and denture cleaning tablets groups. No significant difference was found among the groups in terms of denture stomatitis scores, biofilm, or colony-forming unit count of Candida spp. or C. albicans and S. mutans; a significant reduction was found in these parameters. The 0.25% sodium hypochlorite and 0.15% Triclosan treatments caused a significant reduction in Gram-negative microorganisms; these 2 protocols, and the denture cleaning tablets showed a significant reduction in Staphylococcus spp.; all protocols had similar effects. Only the S. mutans count of the palate decreased after 10 days. The odor level of the mouth and the denture was not significantly different (P=.778).

CONCLUSIONS

The evaluated protocols can be recommended for the hygiene of complete dentures, since they were effective for all the variables studied.

Efficacy of low-molecular weight chitosan against Candida albicans biofilm on polymethyl methacrylate resin

BACKGROUND

Candida biofilm is a major cause of denture stomatitis. We aimed to compare the efficacy of low-molecular-weight chitosan solutions against Candida albicans biofilm on polymethyl methacrylate (PMMA) resin.

METHODS

Various types of chitosan were tested for anti-Candida activity by broth dilution. Two types were selected for further testing on 24-hour C.albicans biofilm formed on PMMA specimens. Specimens were randomly distributed among experimental groups, including 0.1% and 0.2% acetic acid, 3 and 6 mg/mL of oligomer chitosan and 30 kDa chitosan solutions, effervescent tablet (Polident), and 0.2% chlorhexidine, and immersed for 5 min to 12 h. The viability of C. albicans after cleansing were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. Remaining viability was calculated into percentage relative to respective controls and analyzed using ANOVA with Tukey post-hoc tests. Live/dead fluorescence microscopy was also performed.

RESULTS

Chitosan solutions had high efficacy against C. albicans biofilm on PMMA. The mean relative viability compared to control after 12-h immersion was 6.60 ± 4.75% and 12.72 ± 6.96% for 3 and 6 mg/mL oligomer, respectively, and 11.68 ± 4.81% and 18.08 ± 6.20% for 3 and 6 mg/mL 30 kDa chitosan, respectively.

CONCLUSIONS

Low-molecular-weight chitosan solution is an effective antifungal denture cleanser that can significantly reduce C. albicans viability in biofilm on PMMA.

Development of a European consensus from dentists, dental hygienists and physicians on a standard for oral health care in care-dependent older people: An e-Delphi study

OBJECTIVES

This study aimed to obtain a consensus on oral health policy, access to dental care, oral hygiene measures and training levels.

BACKGROUND

Poor oral health is widespread in care-dependent older people, but no consensus for a minimum standard of oral health care exists yet.

METHODS

The e-Delphi approach was applied to a selected panel of interdisciplinary experts. Data analysis was based on three measurements: (a) ≥70% of experts' opinion fall into category "agree or strongly agree," (b) median score on the 5-point Likert scale ≥4, (c) interquartile range ≤1.

RESULTS

A total of 31 experts from 17 European countries participated in this survey. Agreement was achieved for a compulsory dental examination when an elder is admitted to a long-term care (LTC) facility. Older people should brush their teeth twice/day and regularly clean interproximal spaces and oral mucosa. Dentures should be rinsed after meals and cleaned twice/day. The use of denture cleansing tablets was considered necessary. Dentures should be removed before sleeping and stored dry. A 5000 ppm fluoride toothpaste should be applied daily in elder with high caries risk. A short report on the oral health status of the elder should be included in the geriatric assessment. All experts concluded that the knowledge and the training in oral health care for caregivers and family members of care-dependent older people were imperative.

CONCLUSIONS

Using the e-Delphi method, multidisciplinary healthcare professionals from different countries agreed on certain cardinal recommendations for a standard oral health care for care-dependent older people.

Cinnamaldehyde is a biologically active compound for the disinfection of removable denture: blinded randomized crossover clinical study

BACKGROUND

Fungal infections associated with the use of dentures, like denture stomatitis, are difficult to prevent and treat. This in situ study aimed to investigate the efficacy of cinnamaldehyde for the disinfection of complete removable dentures, and the effect on the physical and mechanical properties (Vickers microhardness, color, and surface roughness) of the acrylic resin.

METHODS

Acrylic resin disks were inserted into the dentures of a probabilistic sample of 33 complete denture users, that used cinnamaldehyde (27 μg/mL) and 0.5% sodium hypochlorite solutions in a 20 min/7-days protocol of dentures immersion in each solution, with a wash-out period of 7 days, to constitute a crossover-study. The disks were analyzed before and after the immersion, for the presence of microorganisms (CFU/mL) and by scanning electron microscope (SEM). Also, the surface roughness (Ra) and Vickers microhardness were measured, and color parameters were analyzed using the National Bureau of Standards (NBS) method. Data was analyzed by Wilcoxon and Friedman (microbiological evaluation), paired t-test (color and roughness) and independent t-test (Vickers hardness) (α = 0.05).

RESULTS

A significant reduction (P < 0.05) in the number of microorganisms was observed for each species (total microorganisms, Streptococcus mutans, and Candida spp.), with no significant differences (P > 0.05) between hypochlorite and cinnamaldehyde. There was an increase in the roughness and a decrease in the hardness of the test specimens, with no difference between the two disinfectant substances (P > 0.05). Both hypochlorite and cinnamaldehyde also caused changes in color, considered as "perceptible" by the NBS classification, but with no significant difference between disinfectant substances (P < 0.05), and under the clinically acceptable limit (ΔE ≤ 3.7).

CONCLUSION

The 27 μg/mL cinnamaldehyde solution was effective against all evaluated microorganisms and caused minor alterations in hardness, surface roughness, and color parameters, with no clinical relevance.

Biological and Chemo-Physical Features of Denture Resins

In the dental field, the study of materials has always been the basis of the clinical practice. Over the years, with the evolution of materials, it has been possible to produce safe and predictable prosthetic devices, with ever better aesthetic features, biocompatibility and patient satisfaction. This review briefly analyzes the features of dental resin materials to underline the biological, microbiological and chemo-physical characteristics. The main aim of prosthodontics is to rehabilitate patients and therefore improve their quality of life. Dental resins are the main materials used for the production of dentures. Once solidified, these polymers have different mechanical or surface characteristics. The results of the literature on these characteristics were analyzed and some new brand dental resins, known as modern resin, were subsequently evaluated. The new materials are undoubtedly a step forward in the creation of dental prostheses, and also in all subsequent maintenance phases. This review shows how changing the chemical structure of the resins could have microbiological influences on the growth and management of the biofilm, and also physical influences in terms of its mechanical characteristics. The development of new materials is a constant goal in dentistry in order to obtain increasingly predictable rehabilitations.

Effect of Denture Cleansing Solutions on the Retention of Locator Attachments Over Time

PURPOSE

To evaluate and compare the alterations in retention of three Locator attachments after immersion in various denture cleansers at defined time intervals.

MATERIALS AND METHODS

Two implants were embedded in an acrylic block. Pink, blue, and clear Locator attachments (n = 10 for each subgroup) were immersed into three different cleansing solutions (Corega, Protefix and NaOCl) and tap water (control) at different time intervals that simulate 1 (T₁ ), 6 (T₂ ), and 12 (T₃ ) months of clinical use. Universal testing machine set at a crosshead speed of 50 mm/min was used for pull-out tests. After the immersion procedure, the peak force to dislodgement was recorded to demonstrate the changes in retention of Locator attachments. Data were analyzed using repeated-measures ANOVA followed by Tukey's Honestly Significant Difference (HSD) tests (α = .05).

RESULTS

All denture cleansing solutions affected the retentive values of all Locator attachments at defined time intervals (F = 4.299, p = 0.001). NaOCl affected all groups significantly after 12-month immersion time (p = 0.001). The least retention loss at all subgroups was observed in Corega for clear Locator attachments (106.17 ± 5.21 N). The difference in retention values for pink attachments were not statistically significant for tap water, Protefix and Corega immersion at all time intervals (p > 0.05). Following NaOCl (blue; 33.31 ± 4.72 N, clear; 52.3 ± 8.5 N), tap water decreased the retention value of blue (41.14 ± 3.93 N) and clear (76.72 ± 8.42 N) Locator attachments at T₃ . Corega caused the least retention loss to clear attachments at T₁ (106.17 ± 3.55 N).

CONCLUSION

The retention of Locator attachments decreases over time after exposure to various denture cleansing solutions. As NaOCl significantly decreased the retentive values of all attachments, patients must be informed about that disadvantage. Also, tap water remarkably decreased retentive ability of all attachments. Periodic addition of an effervescent tablet into tap water may be recommended to patients that wear implant retained overdentures with Locator attachments.

Anti-biofilm Action of Chenopodium ambrosioides Extract, Cytotoxic Potential and Effects on Acrylic Denture Surface

Considering the challenge to control Candida-associated denture stomatitis, the search for antifungal substances derived from natural sources has become a trend in the literature. In this study the following effects of Chenopodium ambrosioides extract (CAE) were investigated: action against biofilms of Candida albicans, its cytotoxic potential, and changes caused in acrylic resin. The CAE was characterized by High Performance Liquid Chromatography (HPLC). The susceptibility of C. albicans to CAE was investigated by Minimum Inhibitory Concentration and Minimum Fungicidal Concentration (MIC and MFC) tests. Acrylic resin disks were fabricated, and C. albicans biofilms were developed on these for 48 h. Afterward the disks were immersed for 10 min in: PBS (Negative Control); 1% Sodium Hypochlorite (1% SH, Positive Control) or CAE at MIC or 5xMIC. The biofilms were investigated relative to counts and metabolic activity. The cytotoxic potential in keratinocytes and fibroblasts was verified by MTT test. Change in color and roughness of the acrylic resin was analyzed after 28 days of immersion in CAE. The data were analyzed by the ANOVA considering a 5% level of significance. The main compounds detected by HPLC were kaempferol and quercetin. Both MIC and MFC obtained the value of 0.25 mg/mL. The MIC was sufficient to significantly reduce the counts and activity of the biofilm cells (p < 0.0001), while 5xMIC resulted in almost complete eradication, similar to 1% SH. Keratinocytes and fibroblasts exposed to the MIC and 5xMIC presented cell viability similar to that of the Control Group (p > 0.05). No important changes in acrylic resin color and roughness were detected, even after 28 days. It could be concluded that the immersion of acrylic resin in C. ambrosioides extract in its minimum inhibitory concentration was effective for the reduction of C. albicans biofilms without any evidence of cytotoxic effects or changes in roughness and color of this substrate.

Effect of Terminalia catappa Linn. on Biofilms of Candida albicans and Candida glabrata and on Changes in Color and Roughness of Acrylic Resin

This study aimed to investigate the effect of the n-butanol fraction of Terminalia catappa Linn., (FBuTC) on biofilm of Candida albicans and Candida glabrata, as well as changes in color and roughness of polymethyl methacrylate resin (PMMA). The susceptibility of C. albicans and C. glabrata to FBuTC was evaluated by means of the Minimum Inhibitory and Minimum Fungicidal Concentration (MIC and MFC). PMMA acrylic resin discs (N= 108) were fabricated. For the susceptibility tests, biofilms of C. albicans and C. glabrata were developed on discs for 48 h and immersed in phosphate-saline buffer solution (PBS), 1% sodium hypochlorite (SH 1%), or FBuTC at MIC, 5xMIC, or 10xMIC. For the color and roughness change tests, the discs were immersed in distilled water, SH 1%, or FBuTC in the concentrations of 0.25 mg/mL, 2.5 mg/mL, or 25.0 mg/mL. After 28 days of incubation, color change was evaluated by spectrophotometry and roughness, by using a profilometer. The biofilms were investigated by one-way ANOVA and, the color and roughness changes (two-way ANOVA and the Tukey test; α=0.05). For both MIC and MFC the value of 0.25 mg/mL of FBuTC was observed for the planktonic cells of C. albicans and C. glabrata. Exposure to FBuTC at 10xMIC had a significant effect on the biofilm of C. albicans, showing a reduction in cell counts when compared with PBS, (p=0.001). For the biofilm of C. glabrata, the MIC was sufficient for significantly reducing the cell count (p<0.001). No important changes in color and roughness of the acrylic resin were observed, even after 28 days, irrespective of the concentration of FBuTC used (p >0.05). It could be concluded that the immersion of acrylic resin for dental prosthesis in FBuTC was effective in reducing the biofilms of C. albicans and C. glabrata without evidence of change in roughness and color of this substrate.

Chemical hygiene protocols for complete dentures: A crossover randomized clinical trial

STATEMENT OF PROBLEM

Clinical evidence on the best chemical protocol for the disinfection and removal of biofilm from complete dentures is lacking.

PURPOSE

The purpose of this crossover randomized clinical trial was to assess the effectiveness of various chemical hygiene clinical protocols in reducing the microbial viability of biofilm formed on complete dentures.

MATERIAL AND METHODS

In this triple-blind (participants, dentist, and outcome evaluator) study, complete denture wearers without candidiasis were randomly divided into 4 groups (n=40) according to the chemical hygiene protocol: water (placebo), 0.5% sodium hypochlorite solution, 0.12% chlorhexidine gluconate solution, and 5% sodium bicarbonate solution. The biofilm formed on the palate intaglio and denture teeth was collected and assessed in each experimental phase for quantitative microbial viability at the seventh and 14th day after using the chemical protocol.

RESULTS

Two participants were lost. Data were analyzed by MANOVA and Tukey HSD tests. Soaking dentures was not effective in decreasing Candida albicans, C. non-albicans, and lactobacillus counts. The use of sodium hypochlorite and chlorhexidine decreased total microorganisms and Streptococcus mutans counts for both palate and teeth compared with water and sodium bicarbonate. The intaglio of the dentures always presented higher microbial counts than did the denture teeth.

CONCLUSIONS

The use of sodium hypochlorite and chlorhexidine and mechanical cleansing with a toothbrush decreased microbial viability in healthy complete denture wearers.

Evaluation of biofilm removal and adverse effects on acrylic resin by diluted concentrations of sodium hypochlorite and Ricinus communis solutions

PURPOSE

To verify whether 0.1% and 0.2% sodium hypochlorite (NaOCl), and 8% Ricinus communis (RC) were able to remove denture biofilm without causing deleterious effects to acrylic resin.

BACKGROUND

Previous data show that denture cleansers are effective in reducing biofilm; however, they can change acrylic resin properties.

METHODS

In a crossover trial, 47 denture wearers brushed and soaked their dentures (20 min/14 d): control, 0.85% saline; SH1, 0.1% NaOCl; SH2, 0.2% NaOCl and RC. Denture biofilm on the intaglio surface was stained, photographed and quantified (Image Tool® ). Furthermore, 80 rectangular and 80 disc-shaped specimens (Lucitone 550) were assigned into tested solutions (n = 20), simulating 5 years of daily short immersions (20 minutes). A colorimeter and the National Bureau of Standards units (NBS) determined colour data (ΔE). Surface roughness and flexural strength were measured using rugosimeter and universal testing machine, respectively. Data were compared by the Friedman test (α = .05) followed by Wilcoxon, corrected by Bonferroni (α = .005) (clinical) and Kruskal-Wallis followed by the Dunn test (α = .05) (laboratorial).

RESULTS

SH2 (MR=1.77) showed lower biofilm coverage; SH1 (MR = 2.37) and RC (MR = 2.74) presented intermediated values. RC (1.10 [0.96:1.75]) revealed higher colour alteration than SH1 (0.71 [0.62:0.80]) and SH2 (0.74 [0.58:0.85]); however, NBS classified all solutions as "trace" (0.0-0.5). There was no statistical significance for surface roughness (P = .760) and flexural strength (P = .547).

CONCLUSIONS

The 0.2% NaOCl showed the best clinical performance and did not cause adverse effects on acrylic resin on laboratory analyses.

Efficacy of denture cleaners on the surface roughness and Candida albicans adherence of sealant agent coupled denture base materials

This study investigated the effect of denture cleansers on the surface roughness and Candida albicans adherence of surface sealant agent coupled denture base resins. One hundred and twenty specimens were fabricated from 2 polymethyl methacrylate (PMMA) (Meliodent; Acron MC) and 1 polyamide (Deflex) denture base materials, coated with a sealant agent (Palaseal) and divided into 4 groups (n=10) according to overnight cleaning procedures: distilled water (control), 5% sodium hypochlorite (NaOCl) and two different sodium perborate (Corega; Rapident). The surface roughness values were measured with a profilometer before (R_a0) and after 90 days immersion in denture cleaners (R_a1). Specimens were incubated with Candida albicans suspension and Candida colony- forming units (CFU) (Cfu/mm) were counted. Significant differences were found, between the R_a0 and R_a1 values of 5% NaOCl applied Acron MC, Deflex and also Rapident applied Deflex groups (p<0.05). Denture cleaning procedures had no significant effects on the quantitiy of Candida albicans.

Alkaline Peroxides Versus Sodium Hypochlorite for Removing Denture Biofilm: a Crossover Randomized Trial

This study evaluated the efficacy of cleanser solutions on denture biofilm removal by a crossover randomized clinical trial. Thirty two edentulous patients were instructed to brush their dentures (specific brush and liquid soap) three times a day (after breakfast, lunch and dinner) and to soak them (≥ 8 h) in: (C) control -water; (AP): alkaline peroxide; or (SH) 0.5% sodium hypochlorite. Each solution was used for 21 days (three cycles of 7 days). At the end of each cycle, the inner surfaces of maxillary dentures were disclosed (1% neutral red) and photographed (HX1 - Sony). Areas (total and stained biofilm) were measured (Image Tool software) and the percentage of biofilm calculated as the ratio between the area of the biofilm multiplied by 100 and total surface area of the internal base of the denture. Data were compared by means of generalized estimating equation (α=5%) and multiple comparisons (Bonferroni; α=1.67%). Immersion in SH reduced biofilm (%) (8.3 ± 13.3B) compared to C (18.2 ± 14.9A) and AP (18.2 ± 16.6A). The 0.5% sodium hypochlorite solution was the most efficacious for biofilm removal. Alkaline peroxides may not lead to further biofilm removal in patients with adequate denture maintenance habits.

Antimicrobial activity of complete denture cleanser solutions based on sodium hypochlorite and Ricinus communis - a randomized clinical study

To preserve oral health and to maintain the prosthetic devices, it is important not only to improve the properties of commonly known hygiene products, but also to investigate new materials with antimicrobial action.

In vitro Effects of Lemongrass Extract on Candida albicans Biofilms, Human Cells Viability, and Denture Surface

The purpose of this study was to investigate whether immersion of a denture surface in lemongrass extract (LGE) has effects on C. albicans biofilms, human cell viability and denture surface. Minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC) were performed for LGE against C. albicans. For biofilm analysis, discs were fabricated using a denture acrylic resin with surface roughness standardization. C. albicans biofilms were developed on saliva-coated discs, and the effects of LGE at MIC, 5XMIC, and 10XMIC were investigated during biofilm formation and after biofilm maturation. Biofilms were investigated for cell counting, metabolic activity, and microscopic analysis. The cytotoxicity of different concentrations of LGE to peripheral blood mononuclear cells (PBMC) was analyzed using MTT. The effects of LGE on acrylic resin were verified by measuring changes in roughness, color and flexural strength after 28 days of immersion. Data were analyzed by ANOVA, followed by a Tukey test at a 5% significance level. The minimal concentration of LGE required to inhibit C. albicans growth was 0.625 mg/mL, while MFC was 2.5 mg/mL. The presence of LGE during biofilm development resulted in a reduction of cell counting (p < 0.05), which made the MIC sufficient to reduce approximately 90% of cells (p < 0.0001). The exposure of LGE after biofilm maturation also had a significant antifungal effect at all concentrations (p < 0.05). When compared to the control group, the exposure of PBMC to LGE at MIC resulted in similar viability (p > 0.05). There were no verified differences in color perception, roughness, or flexural strength after immersion in LGE at MIC compared to the control (p > 0.05). It could be concluded that immersion of the denture surface in LGE was effective in reducing C. albicans biofilms with no deleterious effects on acrylic properties at MIC. MIC was also an effective and safe concentration for use.

In Vitro Analysis of Surface Roughness of Acrylic Resin Exposed to the Combined Hygiene Method of Brushing and Immersion in Ricinus communis and Sodium Hypochlorite

PURPOSE

To evaluate a solution based on Ricinus communis (Castor oil) for denture cleansing, comparing it to sodium hypochlorite (NaOCl) for the surface roughness of heat-polymerized acrylic resin.

MATERIALS AND METHODS

Forty polished and unpolished resin specimens (90 × 30 × 4 mm) were evaluated before and after their exposure to protocol hygiene: brushing the specimens with a specific denture brush and mild soap for 3 minutes, three times a day, and immersing them in hygiene solutions (0.25% NaOCl-S1 and 0.5% NaOCl-S2; 10% R. communis-S3; saline-S4: control) for 20 minutes. Surface roughness was evaluated by rugosimeter and scanning electron microscopy (SEM) before and after the protocol. For evaluation of surface roughness, polished and unpolished surfaces were used.

RESULTS

The roughness of the polished surface was not affected by time (p = 0.062), but was affected by solutions (p < 0.0001) and the interaction between factors (p = 0.005). For S1 and S4, the period did not influence the roughness. For S2, there was a change after 7 days, remaining stable after 14 days. For S3, there were changes, and stabilization occurred after 14 days. After 7 and 14 days, S2 and S3 promoted major changes, but after 21 days, there were no differences among solutions, except saline. The unpolished surface was not influenced by factors: period (p = 0.115), solution (p = 0.120), and their interaction (p = 0.382). SEM analysis showed similar results on the evaluation of surface roughness.

CONCLUSIONS

The polished surface of the prosthesis was more susceptible to changes when exposed to hygiene solutions, and although the 0.5% NaOCl solution promoted an increase in the surface roughness compared with the same solution at 0.25% and R. communis at 10%, the values are clinically acceptable.

In vitro treatment of Candida albicans biofilms on denture base material with volume dielectric barrier discharge plasma (VDBD) compared with common chemical antiseptics

OBJECTIVES

To prevent oral candidiasis, it is crucial to inactivate Candida-based biofilms on dentures. Common denture cleansing solutions cannot sufficiently inactivate Candida albicans. Therefore, we investigated the anticandidal efficacy of a physical plasma against C. albicans biofilms in vitro.

MATERIALS AND METHODS

Argon or argon plasma with 1 % oxygen admixture was applied on C. albicans biofilms grown for 2, 7, or 16 days on polymethylmethacrylate discs; 0.1 % chlorhexidine digluconate (CHX) and 0.6 % sodium hypochlorite (NaOCl) solutions served as positive treatment controls. In addition, these two solutions were applied in combination with plasma for 30 min to assess potential synergistic effects. The anticandidal efficacy was determined by the number of colony forming units (CFU) in log(10) and expressed as reduction factor (RF, the difference between control and treated specimen).

RESULTS

On 2-day-biofilms, plasma treatment alone or combined with 30 min CHX treatment led to significant differences of means of CFU (RF = 4.2 and RF = 4.3), clearly superior to CHX treatment alone (RF = 0.6). Plasma treatment of 7-day-or 16-day-old biofilms revealed no significant CFU reduction. The treatment of 7-day-old (RF = 1.7) and 16-day-old (RF = 1.3) biofilms was slightly more effective with NaOCl alone than with the combined treatment of NaOCl and plasma (RF = 1.6/RF = 1.9). The combination of CHX and plasma increased the RF immaterially.

CONCLUSION

The use of plasma alone and in combination with antiseptics is promising anticandidal regimens for daily use on dentures when biofilms are not older than 2 days.

CLINICAL RELEVANCE

Plasma could help to reduce denture-associated candidiasis.