Complete denture biofilm after brushing with specific denture paste, neutral soap and artificial saliva

Strategies for Preventing and Treating Oral Mucosal Infections Associated with Removable Dentures: A Scoping Review

Oral infections occur due to contact between biofilm rich in Candida albicans formed on the inner surface of complete dentures and the mucosa. This study investigated historical advances in the prevention and treatment of oral mucosal infection and identified gaps in the literature. Bibliographic research was conducted, looking at PubMed, Embase, Web of Science, and Scopus, where 935 articles were found. After removing duplicates and excluding articles by reading the title and abstract, 131 articles were selected for full reading and 104 articles were included. Another 38 articles were added from the gray literature. This review followed the PRISMA-ScR guidelines. The historical period described ranges from 1969 to 2023, in which, during the 21st century, in vitro and in vivo studies became more common and, from 2010 to 2023, the number of randomized controlled trials increased. Among the various approaches tested are the incorporation of antimicrobial products into prosthetic materials, the improvement of oral and denture hygiene protocols, the development of synthetic and natural products for the chemical control of microorganisms, and intervention with local or systemic antimicrobial agents. Studies report good results with brushing combined with sodium hypochlorite, and new disinfectant solutions and products incorporated into prosthetic materials are promising.

Effectiveness of Oil-Based Denture Dentifrices-Organoleptic Characteristics, Physicochemical Properties and Antimicrobial Action

Denture dentifrices must be effective and not deleterious to prosthetic devices. This study formulated and evaluated dentifrices based on oils of Copaifera officinalis, Eucalyptus citriodora, Melaleuca alternifolia, Pinus strobus, and Ricinus communis. Organoleptic characteristics (appearance, color, odor, taste), physicochemical properties (pH, density, consistency, rheological, abrasiveness, weight loss, and surface roughness) and antimicrobial (Hole-Plate Diffusion–HPD)/anti-biofilm (Colony Forming Units–CFU) action against Staphylococcus aureus, Streptococcus mutans, and Candida albicans were evaluated. Formulations were compared with water (negative control) and a commercial dentifrice (positive control). The data were analyzed by Kruskal-Wallis and Dunn tests (α = 0.05). The organoleptic and physicochemical properties were adequate. All dentifrices promoted weight losses, with high values for C. officinalis and R. communis, and an increase in surface roughness, without differing from each other. For antimicrobial action, C. officinalis and E. citriodora dentifrices were similar to positive control showing effectiveness against S. mutans and C. albicans and no dentifrice was effective against S. aureus; regarding the anti-biofilm action, the dentifrices were not effective, showing higher CFU counts than positive control for all microorganisms. The dentifrices presented satisfactory properties; and, although they showed antimicrobial action when evaluated by HPD, they showed no effective anti-biofilm action on multispecies biofilm.

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.

In vitro evaluation of the effect of different disinfectants on the biofilm of Staphylococcus epidermidis and Staphylococcus aureus formed on acrylic ocular prostheses

The aim of this study was to evaluate the effect of disinfectants on the biofilm of Staphylococcus aureus and Staphylococcus epidermidis formed on the acrylic surface of ocular prostheses. In this study, 396 acrylic specimens were manufactured (50% for Staphylococcus epidermidis, and 50% for Staphylococcus aureus). For each bacterium, 66 specimens were subjected to biofilm formation on their surfaces for 24 hours, 66 specimens were subjected to biofilm formation on their surfaces for 48 hours, and 66 specimens were subjected to biofilm formation on their surfaces for 72 hours. Then, they were divided into groups according to disinfection method (n = 6): sterile distilled water for 10, 15, 30 min, and 6 hours (control); soap for 30 min (NES30); Opti-Free for 30 min (OPF30) and 6 h (OPF6); Efferdent for 15 min (EFF15); and 0.5%, 2%, and 4% chlorhexidine for 10 min (0.5% CHX10, 2% CHX10, and 4% CHX10). After the treatments, the specimens were vortexed to release the biofilm and the counting of bacterial colonies was performed (CFU/mL). Three-way ANOVA and the Tukey-Kramer HSD test were used (α = 0.05). For Staphylococcus epidermidis, there was no significant difference between NES30, OPF30, and OPF6 with their respective control groups; nor between NES30, OPF30, and OPF6 themselves, regardless of the biofilm development period (P >0.05). For Staphylococcus aureus, there was no significant difference between NES30 and OPF30 with their control group; nor between NES30 and OPF30 themselves, regardless of the biofilm development period (P >0.05). For Staphylococcus aureus, OPF6 showed a significant reduction in the number of CFU/mL when compared with its control group, NES30, and OPF30, regardless of the biofilm development period (P <0.05). For both bacteria, 0.5% CHX10, 2% CHX10,4% CHX10, and EFF15 showed a significant reduction in the number of CFU/mL when compared with their control groups, NES30, OPF30, and OPF6, regardless of the biofilm development period (P <0.05). Therefore, EFF15 and CHX (0.5%, 2% and 4%) were effective in reducing Staphylococcus epidermidis and Staphylococcus aureus on acrylic surfaces. NES30 and OPF (30 and 6) are not recommended.

Accuracy of a questionnaire on xerostomia as a screening tool for hyposalivation

OBJECTIVE

Determine the accuracy of a questionnaire on xerostomia as a screening tool for hyposalivation.

METHODS

A total of 402 adults awaiting dental care at a public healthcare service answered an eight-item questionnaire addressing xerostomia and were submitted to stimulated sialometry, with ≤ 0.7 mL/min considered indicative of hyposalivation. Reproducibility and internal consistency of the questionnaire were evaluated. The correlation between the score and salivary flow was investigated. The total score was also compared between groups with and without hyposalivation and diagnostic precision measures were calculated.

RESULTS

Hyposalivation was identified in 162 participants (40.3%) and a total of 229 (57.0%) answered affirmatively to at least one question. The responses to each question revealed variable reproducibility (κ = 0.450-0.785) and satisfactory internal consistency (Cronbach's α = 0.70). Individuals with a larger number of positive answers had lower salivary flow (Spearman's ρ = -0.193; P < 0.001). The mean number of positive answers was greater in the group with a clinical diagnosis of hyposalivation compared to those without low salivary flow. The sensitivity of the screening tool was 64.8%, with an area under the ROC curve of 0.60 (95% confidence interval: 0.547-0.645; P < 0.001).

CONCLUSION

The questionnaire proved to be useful for the epidemiological screening of individuals with possible hyposalivation.

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.

Candida albicans biofilm heterogeneity does not influence denture stomatitis but strongly influences denture cleansing capacity

Approximately 20  % of the UK population wear some form of denture prosthesis, resulting in denture stomatitis in half of these individuals. Candida albicans is primarily attributed as the causative agent, due to its biofilm -forming ability. Recently, there has been increasing evidence of C. albicans biofilm heterogeneity and the negative impact it can have clinically; however, this phenomenon has yet to be studied in relation to denture isolates. The aims of this study were to evaluate C. albicans biofilm formation of clinical denture isolates in a denture environment and to assess antimicrobial activity of common denture cleansers against these tenacious communities. C. albicans isolated from dentures of healthy and diseased individuals was quantified using real-time PCR and biofilm biomass assessed using crystal violet. Biofilm development on the denture substratum poly(methyl methacrylate), Molloplast B and Ufi-gel was determined. Biofilm formation was assessed using metabolic and biomass stains, following treatment with denture hygiene products. Although C. albicans was detected in greater quantities in diseased individuals, it was not associated with increased biofilm biomass. Denture substrata were shown to influence biofilm biomass, with poly(methyl methacrylate) providing the most suitable environment for C. albicans to reside. Of all denture hygiene products tested, Milton had the most effective antimicrobial activity, reducing biofilm biomass and viability the greatest. Overall, our results highlight the complex nature of denture- related disease, and disease development cannot always be attributed to a sole cause. It is the distinct combination of various factors that ultimately determines the pathogenic outcome.

Effect of different cleaning methods of polyetheretherketone on surface roughness and surface free energy properties

PURPOSE

To determine the effect of different individual, laboratory and professional cleaning methods on the surface-roughness (SR) and surface free energy (SFE) of polyetheretherketone (PEEK), PMMA-based (PMMA) and composite (COMP) materials.

METHODS

330 specimens of PEEK, PMMA and COMP (N = 990) were prepared and divided into the following cleaning protocols (n = 30/group): (i) individual prophylaxis using (ST) soft, (MT) medium-hard and (SOT) sonic toothbrushes, (ii) in-lab cleaning protocols consisting of (SY) Sympro cleaning system, (SS) SunSparkle, (UB) ultrasonic bath and (AP) Al2O3-powder device and (iii) professional prophylaxis applying (PS) Perio Soft-Scaler, (SO) Sonicsys, (AFC) Air Flow Comfort, and (AFP) Air Flow Plus. After each protocol SR (profilometer), SFE (contact angle devise) and surface topography (SEM) were measured. Data were analyzed using multivariate analysis, Kruskal-Wallis-H- and Mann-Whitney-U-test (p&lt;0.05).

RESULTS

No impact of material on SR was observed (p = 0.443). Cleaning using conventional air-abrasion and powders (AP), followed by AFC produced higher SR values than the remaining methods (p&lt;0.001). Within SFE, the cleaning method exerted the highest influence on SFE values (p&lt;0.001, ηP2 = 0.246), closely followed by the polymer material (p&lt;0.001, ηP2 = 0.136). PMMA and PEEK presented after cleaning lower SFE than COMP. PS, UB and SO showed lower SFE than specimens cleaned using SS, ST and SY. Cleaning using SY led to the highest SFE.

CONCLUSIONS

With regard to SR, all methods - with exception of conventional air-abrasion - can be recommended to clean PEEK. According to the SFE, PEEK may be an acceptable material providing even lower plaque accumulation rates than COMP. The field for more research is now open for scrutiny.

Trial of an experimental castor oil solution for cleaning dentures

Denture hygiene is essential because denture biofilm is involved in oral infections and systemic diseases. Although there are chemical agents available on the market, none of them have ideal properties and research on such products is still necessary. The aim of this study was to evaluate the efficacy of a castor bean (Ricinus communis)-based solution for removing denture biofilm, compared to two traditional products (sodium hypochlorite and alkaline peroxide). Fifty maxillary complete denture wearers were instructed to brush their dentures after meals and to immerse their dentures once a day in the following solutions: Saline (20 min; control), Polident alkaline peroxide (3 min), NaOCl (20 min) and 2% castor oil solution (20 min). Participants used each solution for a period of 7 consecutive days, according to a random sequence. After each period, the internal surfaces of maxillary complete dentures were stained with a disclosing solution (1% neutral red), photographed and the disclosed biofilm was quantified with the aid of specific software. The influence of treatments on results was verified by the Friedman test (α=0.05). Tested solutions presented significant difference (Fr=51.67; p<0.001). Saline and NaOCl were significantly different (median: 2.0% and 0.0%) whereas Polident and castor oil presented intermediate results (median: 1.0% and 1.5%, respectively). It can be concluded that the castor oil solution tested in this study was comparable to alkaline peroxide in terms of efficiency in denture biofilm removal.

Effect of Disinfection on the Bond Strength between Denture Teeth and Microwave-Cured Acrylic Resin Denture Base

PURPOSE

Denture tooth debonding is a common complication for denture wearers; however, the effect of complete denture disinfection on bonding between denture teeth and acrylic resin remains unclear. The aim of this study was to evaluate the effect of disinfection methods on the bond strength between denture teeth and microwave-cured acrylic resin denture base.

MATERIALS AND METHODS

Three commercial brands of denture teeth (Trilux, Biolux, Vipi Dent Plus) and one microwave-cured acrylic resin denture base were tested. Each brand of denture teeth was divided into seven groups (n = 6; estimated by partial Eta squared). The specimenss of groups H and Cl were immersed in 1% sodium hypochlorite and 4% chlorhexidine digluconate for 7 days, respectively. In group Br, the specimens were subjected to toothbrush simulation under 200 g of force for 20,000 cycles. In groups Br-H and Br-Cl, the specimens were brushed and further disinfected with 1% sodium hypochlorite and 4% chlorhexidine digluconate, respectively. In control groups 1 (Co1) and 2 (Co2), the specimens were stored in distilled water for 50 ± 2 hours and 7 days, respectively. Shear bond strength testing was performed at the resin/tooth interface in a universal testing machine at a 1 mm/min crosshead speed. The failure pattern was quantified and classified into adhesive, cohesive, or mixed. Data were analyzed using two-way ANOVA and Tukey HSD test (α = 0.05).

RESULTS

Disinfection with 1% sodium hypochlorite (p = 0.031), brushing (p < 0.0001), and association of brushing with either 1% sodium hypochlorite (p < 0.0001) or 4% chlorhexidine digluconate (p = 0.01) reduced the bond strength between denture teeth and microwave-cured acrylic resin denture base. All commercial brands of denture teeth presented a similar bond strength (p > 0.05). The failure pattern was predominantly adhesive independent of the disinfection method and denture tooth brand.

CONCLUSIONS

Disinfection with sodium hypochlorite, brushing, and the association of mechanical and chemical methods reduced the bond strength between denture tooth and microwave-cured acrylic resin denture base.

Antimicrobial action of sodium hypochlorite and castor oil solutions for denture cleaning - in vitro evaluation

The objective of this in vitro study was to evaluate the antimicrobial action of sodium hypochlorite (0.25% and 0.50%) and 10% castor oil solutions against specific microorganisms, by counting Colony Forming Units (CFU) of clinically important bacteria and Candida species. Acrylic resin specimens (n = 320; Lucitone 550) were obtained from square metal matrices (10 x 10 x 2 mm), sterilized by microwave (650W, for 6 minutes) and contaminated by Staphylococcus aureus, Pseudomonas aeruginosa, Candida albicans, Bacillus subtilis, Escherichia coli, Streptococcus mutans, Enterococcus faecalis and Candida glabrata. The specimens were immersed for 20 minutes in one of the following hygiene solutions (n = 10/each): A - 0.25% Sodium hypochlorite; B - 0.5% Sodium hypochlorite; C - 10% Castor oil solution; and D (Control) - saline. Adhered cells were suspended and inoculated into a selective solid medium (37ºC for 24 h). The Student's t-test (α = 0.05) was performed to compare log10(CFU+1)/mL between Groups C and D. The results showed that sodium hypochlorite (0.25% and 0.5%) completely eliminated all detectable microorganisms. The castor oil solution eliminated B. subtilis and reduced counts for other strains. Differences between C and D were significant (p < 0.05) for all species except for E. faecalis. Both sodium hypochlorite solutions (0.25% and 0.5%) were effective in eliminating all microorganisms evaluated, and may be useful as cleaning solutions for complete dentures. The castor oil solution provided moderate efficacy and performed differently on the tested species, with the strongest effect on B. subtilis and with non-significant action on E. faecalis.

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.

Effect of cleanser solutions on the color of acrylic resins associated with titanium and nickel-chromium alloys

This study evaluated the effect of cleanser solutions on the color of heat-polymerized acrylic resin (HPAR) and on the brightness of dental alloys with 180 immersion trials. Disk-shaped specimens were made with I) commercially pure titanium, II) nickel-chromium-molybdenum-titanium, III) nickel-chromium molybdenum, and IV) nickel-chromium-molybdenum beryllium. Each cast disk was invested in the flasks, incorporating the metal disk into the HPAR. The specimens (n=5) were then immersed in solutions containing: 0.05% sodium hypochlorite, 0.12% chlorhexidine digluconate, 0.500 mg cetylpyridinium chloride, a citric acid tablet, one of two different sodium perborate/enzyme tablets, and water. The color measurements (∆E) of the HPAR were determined by a colorimeter in accordance with the National Bureau of Standards. The surface brightness of the metal was visually examined for the presence of tarnish. The results (ANOVA; Tukey test-α=0.05) show that there was a significant difference between the groups (p<0.001) but not among the solutions (p=0.273). The highest mean was obtained for group III (5.06), followed by group II (2.14). The lowest averages were obtained for groups I (1.33) and IV (1.35). The color changes in groups I, II and IV were slight but noticeable, and the color change was considerable for group III. The visual analysis showed that 0.05% sodium hypochlorite caused metallic brightness changes in groups II and IV. It can be concluded that the agents had the same effect on the color of the resin and that the metallic alloys are not resistant to the action of 0.05% sodium hypochlorite.