Microwave disinfection of dentures for the treatment of oral candidiasis

Resilient liner modified by antimicrobials for denture stomatitis treatment: A randomized controlled trial

OBJECTIVES

This randomized clinical trial evaluated the effectiveness of an interim denture resilient liner (Trusoft) modified with minimum inhibitory concentrations (MICs) of antimicrobial agents for Candida albicans biofilm in the denture stomatitis (DS) treatment.

METHODS

Forty participants with DS and maxillary complete denture (MCD) wearers were randomly assigned to one of the treatments for 14 days (n=10): nystatin oral suspension (Control-100,000IU/mL; 4 × /day), MCD relined with Trusoft either without (Tru) or with nystatin (Ny) or chlorhexidine diacetate (Chx) at MICs. Cytological smears and mycological quantitative cultures were taken from the palate and denture before treatment (baseline), at the end of treatment (day 14), and at follow-up (days 30, 45, and 60). Photographs of the palate were made at each visit. Data were analyzed by the Cochran and χ² tests, ANOVA and the Tukey test or the Friedman and Kruskal-Wallis tests (α=0.05).

RESULTS

Palatal smears of the Ny and Chx groups exhibited no mycelial Candida (0%) on day 14, and, at the 60-day follow-up, it was observed for only 1 participant from Chx group. MCD smears showed reduction in mycelial forms for all groups on day 14 (P<0.05), but this difference was maintained at follow-up only for the relined dentures (P<0.05). Unlike Tru and the control groups, Ny and Chx groups evidenced a significant reduction in CFU/mL values and DS severity throughout the trial (P<0.05).

CONCLUSIONS

The addition of nystatin and chlorhexidine at MICs to an interim resilient liner is a promising treatment for DS, with better results than those for conventional therapy with nystatin suspension, including the follow-ups.

CLINICAL SIGNIFICANCE

Compared with conventional topical antifungal therapy, modifying a denture reline material with antimicrobials provided a therapeutic option for denture stomatitis. This non-invasive, straightforward therapeutic approach can be easily adopted by dentists and has the advantage of not requiring patient compliance while maintaining therapeutic concentrations on the denture base.

Do denture cleansers influence the surface roughness and adhesion and biofilm formation of Candida albicans on acrylic resin? Systematic review and meta-analysis

PURPOSE

To evaluate the influence of denture cleansers on the surface roughness, Candida albicans adhesion, and biofilm formation on denture base acrylic resins.

STUDY SELECTION

Electronic databases and gray literature were searched using an individual search strategy. In vitro studies that evaluated the effects of immersion in denture cleansers on the surface roughness (µm) and antimicrobial activity (CFU/mL) on samples of heat-polymerized denture base acrylic resins were included.

RESULTS

After screening, 17 studies were included, and a qualitative synthesis was performed. After assessing the risk of bias, only nine studies were included in the meta-analysis. The meta-analysis results showed that the evaluated solutions (0.5% sodium hypochlorite, 1% sodium hypochlorite, alkaline peroxide, and natural substances) did not influence the roughness of the acrylic resin. However, in the qualitative analysis, it was not possible to confirm an association between roughness and C. albicans adhesion and biofilm formation on the acrylic resin samples.

CONCLUSION

Denture cleansers did not affect the surface roughness of denture base acrylic resins.

Dimensional Stability of Elastomeric Impression Material After Disinfection Via Immersion and Microwave Irradiation

Aims:

This study aimed to evaluate and compare the dimensional stability of two elastomeric impression materials, namely polyvinyl siloxane (PVS) and vinyl siloxanether (VSE), subjected to chemical immersion and microwave irradiation for disinfection.

Materials and Methods:

Sixty discs of PVS and VSE impression materials each were prepared using a stainless-steel test die and ring in accordance with ANSI/ADA Specification No. 19. Twenty discs of each impression material were disinfected by chemical immersion for 10 min; another 20 discs were subjected to dry microwave irradiation for 3 min. The other 20 discs served as a control group. Dimensional stability measurements were then performed using an image analyzer at 20× magnification. The data were analyzed by one-way analysis of variance (α=0.05) and Bonferroni (post hoc) test for multiple comparisons to detect significant differences between the groups.

Results:

When subjected to microwave irradiation, both PVS and VSE showed dimensional changes, but the changes were within the limit of 1.5% set by ANSI/ADA (P<0.00). VSE showed markedly better results than PVS for both disinfection methods. The immersion disinfection method resulted in a higher average percentage of linear dimensional changes than both the microwave irradiation and the control for VSE and PVS impression materials.

Conclusion:

VSE exhibited excellent dimensional stability than PVS under both chemical immersion and microwave irradiation. Microwave irradiation using conventional microwave ovens can be used in clinical settings as an alternative to other disinfection techniques because the dimensional changes of the elastomeric impression materials subjected to microwave irradiation have been observed to be within the clinically acceptable limit set by the ANSI/ADA standard.

Is there an optimal method to detach Candida albicans biofilm from dental materials?

Introduction. Candida albicans can produce a complex, dynamic and resistant biofilm on the surface of dental materials, especially denture base acrylic resins and temporary soft liners. This biofilm is the main aetiological factor for denture stomatitis, an oral inflammatory condition characterized by chronic and diffuse erythema and oedema of the denture bearing mucosa.Gap Statement. There is no consensus in the literature regarding the best method to detach biofilms from dental materials. In order to assess the antifungal efficacy of new materials and treatments, the biofilm needs to be properly detached and quantified.Aim. This study compared different methods of detaching C. albicans biofilm from denture base acrylic resin (Vipi Cril) and temporary soft liner (Softone) specimens.Methodology. Specimens of each material were immersed in an inoculum of C. albicans SC5314 and remained for 90 min in orbital agitation at 75 r.p.m. and 37 °C. After the removal of non-adherent cells, the specimens were immersed in RPMI-1640 medium for 48 h. Biofilm formation was evaluated with confocal laser scanning microscopy (n=5). Then, other specimens (n=7) were fabricated, contaminated and immersed in 3 ml of sterile phosphate-buffered saline (PBS) and vortexed or sonicated for 1, 2, 5, or 10 min to detach the biofilm. The quantification of detached biofilm was performed by colony-forming unit (c.f.u.) ml^-1 count. Results were submitted to one-way analysis of variance (ANOVA)/Tukey HSD test (α=0.05).Results. A mature and viable biofilm was observed on the surfaces of both materials. For both materials, there was no significant difference (P>0.05) among detachment methods.Conclusion. Any of the tested methods could be used to detach C. albicans biofilm from hard and soft acrylic materials.

Should local drug delivery systems be used in dentistry?

In dentistry, the use of biomaterial-based drug delivery systems (DDS) aiming the release of the active compounds directly to the site of action is slowly getting more awareness among the scientific and medical community. Emerging technologies including nanotechnological platforms are offering novel approaches, but the majority are still in the proof-of-concept stage. This study critically reviews the potential use of DDS in anesthesiology, oral diseases, cariology, restorative dentistry, periodontics, endodontics, implantology, fixed and removable prosthodontics, and orthodontics with a special focus on infections. It also stresses the gaps and challenges faced. Despite numerous clinical and pharmacological advantages, some disadvantages of DDS pose an obstacle to their widespread use. The biomaterial's biofunctionality may be affected when the drug is incorporated and may cause an additional risk of toxicity. Also, the release of sub-therapeutic levels of drugs such as antibiotics may lead to microbial resistance. Multiple available techniques for the manufacture of DDS may affect drug release profiles and their bioavailability. If the benefits outweigh the costs, DDS may be potentially used to prevent or treat oral pathologies as an alternative to conventional strategies. A case-by-case approach must be followed.

Gene expression of Candida albicans strains isolates from patients with denture stomatitis submitted to treatments with photodynamic therapy and nystatin

The study evaluated the effect of antimicrobial photodynamic therapy (aPDT) and nystatin (NYS) in the expression of genes (ACT1, ALS1, CAP1, CAT1, EFG1, HWP1, LIP3, PLB1, SAP1, and SOD1) involved in the virulence of Candida albicans strains recovered from patients with denture stomatitis (DS). These strains were isolated from the patients before (initial) and after treatment (final), and 45 days after the treatments (follow-up). For gene expression analyses, RNA was isolated from the clinical strains, followed by cDNA synthesis and qPCR using specific primers for each target gene. The samples that present integrity were pooled to increase the RNA yield. In the end, four patients treated with aPDT and five patients treated with NYS had the clinical isolates of C. albicans submitted to gene expression evaluation. The data demonstrated a statistical difference in the expression of PLB1 and ACT1 for the different therapies (aPDT versus NYS). Also, there was a statistical difference in the expression of CAT1, SOD1, and LIP3 at the time intervals assessed (initial, final, and follow-up). In contrast, no statistical difference was found in the expression of ALS1, HWP1, EFG1, CAP1, CAT1, SOD1, LIP3, and SAP1 between the therapies, while no significant difference was detected at the time intervals evaluated for ALS1, HWP1, EFG1, CAP1, and SAP1. Therefore, the topical treatments for DS with aPDT or NYS did not effect the expression of most C. albicans virulence genes evaluated.

Phytotherapy in the management of denture stomatitis: A systematic review and meta-analysis of randomized controlled trials

Medicinal plant extracts are commonly applied for infectious diseases and are perceived as alternatives to conventional antimicrobial agents. We aimed to confirm the efficacy of phytotherapy for denture stomatitis compared with conventional therapies and placebo. A comprehensive literature search was conducted in Pubmed, Embase, Cochrane Library (CENTRAL), Scopus, and Web of Science, in addition to manual searching. Randomized controlled trials (RCTs) published in English, and studying the treatment of denture stomatitis with herbal medicines, were included. The outcome measures included the relief of clinical signs, reduced Candida colony counts, adverse effects, and patient satisfaction. Nineteen RCTs were included for a systematic review based on selection criteria. Two of them were analyzed using a random-effects model. There was no difference in the relief of clinical signs (odds ratio (OR) = 0.96; 95% confidence interval (CI): 0.43-2.15) and microbiological improvement (OR = 1.74; 95% CI: 0.55-5.45) between propolis and miconazole. Most of the included studies showed that phytomedicines had fewer side effects and more patient satisfaction than antifungals or disinfectants. However, further RCTs with more standardly prepared herbal formulations are required to verify the clinical efficacy of phytotherapy as an alternative or adjunctive therapy for denture stomatitis.

The effectiveness of microwave disinfection in treating Candida-associated denture stomatitis: a systematic review and metaanalysis

OBJECTIVE

To evaluate the effectiveness of microwave disinfection in treating Candida-associated denture stomatitis (CADS).

MATERIALS AND METHODS

The PubMed/MEDLINE, Embase, and Scopus databases were searched for reports on randomized clinical trials (RCTs) published in English until May 2020 (PROSPERO CRD42020192062) that evaluated the treatment of CADS by using microwave disinfection. The main outcomes were the improvement of clinical signs and/or the decrease in the residual yeast present on the dentures and palatal mucosa. The mean differences, standard deviations, risk ratio, and 95% confidence interval were calculated by using the random-effects model. Heterogeneity was assessed by using Cochran's Q test and I² values. The level of significance was set at α = 0.05.

RESULTS

Five RCTs with 245 participants were included. The descriptive investigations demonstrated that microwave disinfection was as effective (p > 0.05) as 0.2% chlorhexidine, 0.02% sodium hypochlorite, and topical nystatin (100.000 IU/mL), and was superior to topical miconazole in treating CADS. The metaanalysis did not show a statistical difference between microwave disinfection and nystatin (100.000 IU/mL) treatment in terms of mycological counts, cure, and recurrence rates (p > 0.05).

CONCLUSION

Microwave disinfection showed comparable results with those of conventional therapies for treating CADS. In addition, treatment with 650 W for 3 min once a week for 14 days had better cost-effect results, indicating both the prevention and treatment of CADS.

CLINICAL RELEVANCE

Our findings provide evidence regarding the treatment of CADS using microwave disinfection, and also indicating the best cost-effective option for this treatment modality.

Antifungal activity of Punicalagin-nystatin combinations against Candida albicans

OBJECTIVES

Oral candidiasis is the most common opportunistic fungal infection of oral mucosa and results from an overgrowth of Candida, especially Candida albicans. The potential anti-C. albicans and cytotoxicity of punicalagin (PCG), isolated from Punica granatum, alone or with nystatin (NYS) were evaluated.

METHODS

Activity of compounds alone or in combinations was determined against two C. albicans strains (ATCC 90028 and SC5314). Minimal inhibitory concentration (MIC)-50 and Minimum Fungicidal Concentration (MFC) were assessed by XTT assay and CFU counts, respectively. For combinations, determination of fractional inhibitory concentration index was performed. Ergosterol pathway was investigated as a possible PCG antifungal mechanism. Cytotoxicity assays were undertaken on human primary oral keratinocytes and gingival fibroblasts incubated with antifungal concentrations of PCG and/or NYS for 24 hr.

RESULTS

Combination of NYS and PCG increased antifungal efficacy, compared with compounds tested alone. Combinations 4 (PCG-6.25 μg/ml; NYS-3.9 μg/ml) and 5 (PCG-12.5 μg/ml; NYS-1.95 μg/ml) were more effective since they reduced the MIC-50 of PCG (50 μg/ml) by 8 and 4 times, respectively, increased the candidal inhibition and nullified the PCG cytotoxicity for keratinocytes. PCG antifungal mechanism did not involve ergosterol biosynthesis pathway.

CONCLUSIONS

The favorable outcomes for combination of PCG and NYS encourage further testing this therapeutic strategy against C. albicans.

Candida-Associated Denture Stomatitis and Murine Models: What Is the Importance and Scientific Evidence?

Considering the high prevalence and recurrence of Candida-associated denture stomatitis (CADS), in vivo studies in animal models are necessary before those in humans to evaluate new therapeutic strategies. This study aimed to review the literature on murine models of CADS induction using acrylic intraoral devices simulating dentures. Rats are recommended as experimental animals in these models as well as the adoption of a pasty diet. For maintenance in the proper position during the experiments, intraoral appliances must be obtained by individual impressions, using and retained exclusively by cementation on the molars. The region of interest for histopathological analysis was standardized as that corresponding to the area between the first molars. However, there is no consensus among the studies on the CADS induction rat models in relation to the Candida albicans inoculation and need for immunosuppression and/or administration of antibacterial drugs of animals. The greatest difficulty of the available models refers to maintaining the course of the lesion for a sufficient period to evaluate the effectiveness of the proposed treatment, considering the rapid and efficient murine immune response to candidal colonization. Therefore, future studies are necessary for the development of a robust and reproducible CADS model.

Peel bond strength and antifungal activity of two soft denture lining materials incorporated with 1% chlorhexidine diacetate

Two soft denture lining materials (SC-Soft Confort and TS-Trusoft) were investigated with and without the addition of 1.0% of chlorhexidine diacetate (1.0% CHX). To assess peel bond strength, specimens (75×10×6 mm) were submitted to a peel test at 10 mm/min immediately and after 24 h. To evaluate Candida albicans growth inhibition, disc of specimens (10×3 mm) were immersed in a solution with 3×10⁶ CFU/mL of C. albicans, and spectral measurements were made following immersion in MTT solution for 2, 4, and 6 days. The agar diffusion test was performed by investigating the diameters of inhibition zones around the disc of specimens (10×3 mm)after 48 h. Data were submitted to statistical analysis (α=0.05) and the failure modes were visually classified. The incorporation of 1.0% CHX significantly decreased the peel bond strength for TS (p=0.001) and SC (p=0.005) for immediate test and for TS after 24 h (p=0.010), but not for SC. C. albicans growth was decreased for both materials over time (p<0.05). SC presented inhibition zones approximately 2.0 times larger than TS. The incorporation of 1.0% CHX inhibited fungal growth without impairment to the peel bond strength for SC after 24 h.

Antimicrobial and cytotoxic effects of denture base acrylic resin impregnated with cleaning agents after long-term immersion

The coadjutant method for denture cleansing most used by denture wearers is immersion in chemical agents, which are toxic when in direct contact with cells. However, clinically, the contact between these chemical agents and prosthetic tissues does not occur directly, but rather with what remained impregnated into acrylic bases, even after rinsing the disinfected dentures. This study evaluated the antimicrobial and cytotoxic effects of a denture acrylic resin after successive cycles of daily overnight immersion in 1% sodium hypochlorite (1%NaClO) and 2% chlorhexidine digluconate (2%CHX), simulating the periods of 9 months or 1.5 year. Microbiological and cytotoxic assays were performed, respectively, by broth microdilution method (Candida albicans or Staphylococcus aureus) and MTT assay. Chemical residues of 2%CHX impregnated into the denture acrylic resin had an antimicrobial effect on both immersion periods, which was not observed with those of 1%NaClO. However, residues of 2%CHX were severely cytotoxic to human gingival fibroblasts compared to those of 1%NaClO and acrylic resin (not submitted to the denture cleansers), which were slightly cytotoxic. Even at low concentrations recommended for overnight soaking of removable dentures, the chemical residues of CHX may result in some degree of toxicity to the denture-bearing mucosa after long-term daily immersion.

Cytotoxic potential of denture base and reline acrylic resins after immersion in disinfectant solutions

STATEMENT OF PROBLEM

The daily immersion of dentures in disinfectant solutions can cause the incorporation of toxic substances in the acrylic resins, and studies evaluating the cumulative effect of disinfectant solutions on cell culture are lacking.

PURPOSE

The purpose of this in vitro study was to evaluate the cytotoxic potential of cell cultures of denture base and reline acrylic resins after immersion in disinfectant solutions.

MATERIAL AND METHODS

Disk-shaped specimens (14×1.2 mm) were obtained and divided into groups (n=9) according to the disinfectant solutions (distilled water [control], 2% chlorhexidine digluconate, 3.8% sodium perborate, 0.5% sodium hypochlorite, and apple vinegar) and to the storage period (0, 1, 3, and 6 months). Solutions were changed daily. After the different storage periods, specimens were immersed in culture medium for 24 hours, and extracts were obtained. Human keratinocytes were cultivated, and the cellular metabolism was evaluated by using Alamar Blue. Data were submitted to 3-way analysis of variance and Games-Howell post hoc tests (α=.05).

RESULTS

Both of the acrylic resins tested showed similar biocompatibility properties after immersion in different solutions (P=.400). Immersion in distilled water, 3.8% sodium perborate, and 0.5% sodium hypochlorite did not affect the cellular metabolism of the keratinocytes (P>.05), regardless of the immersion period and the type of acrylic resin (P>.05). Immersion in 2% chlorhexidine digluconate or apple vinegar resulted in high cytotoxicity over time, until the third month (P<.05), after which no changes were observed (P>.05).

CONCLUSIONS

The type of acrylic resin (base or reline) had no significant effect on the viability of cells. Vinegar and chlorhexidine digluconate solutions increased in cytotoxic effect over time, and were strongly cytotoxic after 6 months of immersion. Sodium perborate and sodium hypochlorite were noncytotoxic in all periods of time tested.

Effect of Incorporation of Antifungal Agents on the Ultimate Tensile Strength of Temporary Soft Denture Liners

PURPOSE

To investigate the ultimate tensile strength of temporary soft denture liners modified by minimum inhibitory concentrations (MICs) of antifungal agents for Candida albicans biofilm (SC5314) determined in previous microbiological research.

MATERIALS AND METHODS

Dumbbell-shaped specimens (n = 7) with a central cross-sectional area of 6 × 3 × 33 mm were produced by Softone and Trusoft, without (control) or with incorporation of drugs in powder form at MICs for C. albicans biofilm (per g of material powder): nystatin (0.032 g), chlorhexidine diacetate (0.064 g), ketoconazole (0.128 g), miconazole (0.256 g), and itraconazole (0.256 g). After plasticization, specimens were immersed in distilled water at 37°C for 24 hours, 7 or 14 days, and then tested in tension in a universal testing machine at 40 mm/min. Data of tensile strength (MPa) and elongation percentage (%) were submitted to 3-way ANOVA and Tukey's test (α = 0.05).

RESULTS

At the end of 14 days, the tensile strength for both materials was significantly lower in the groups modified by miconazole and itraconazole compared to the other groups (p < 0.0001), which showed no significant difference between them (p > 0.05). After 7 and 14 days in water, miconazole and itraconazole added into both materials resulted in significantly lower elongation percentages compared to the other antifungal agents and control (p < 0.0001), which were similar to each other (p > 0.05).

CONCLUSIONS

The addition of the nystatin, chlorhexidine, and ketoconazole at MICs for C. albicans biofilm resulted in no harmful effects on the tensile strength and elongation percentage of the temporary soft denture liner materials up to 14 days.

Evaluation of Surface Microhardness Following Chemical and Microwave Disinfection of Commercially Available Acrylic Resin Denture Teeth

INTRODUCTION

Denture disinfection is an indispensable procedure for preventing cross contamination and the maintenance of a healthy oral mucosa in patients rehabilitated with removable dental prosthesis. Nevertheless, they are known to cause changes in the physical and mechanical properties of denture base resins and acrylic resin denture teeth following immersion of a denture in a suitable chemical disinfectant solution or by undergoing microwave irradiation. One such mechanical property indicator for artificial tooth materials is hardness.

AIM

To assess the surface hardness of acrylic resin teeth of three different commercial brands (Ivoclar, Newace, Acryrock) following chemical (2% glutaraldehyde, 1% sodium hypochlorite) and microwave disinfections.

MATERIALS AND METHODS

Ten specimens of each of the three commercial brands were made for control and each simulated disinfection type and stored in distilled water at room temperature for 24 hours. After water storage, specimens were immersed in 2% glutaraldehyde and 1% sodium hypochlorite (one and three cycles) at room temperature for 10 minutes. Irradiation with microwave (one and three cycles) was done in domestic microwave for three minutes with the specimens immersed in 150 ml of distilled water. The specimens were stored in distilled water at room temperature for seven days after each disinfection cycle. Vickers hardness measurements were made using a hardness indenter under a load of 50 g force for 10 seconds. Data was subjected to repeated measure two-way ANOVA test and Tukey's test.

RESULTS

There were statistically significant differences for the variables disinfection, tooth, and cycle (p<0.05 for teeth & disinfectant interaction, p<0.05 cycle and disinfectant interaction). The mean surface hardness following one microwave disinfection cycle was lower than control, glutaraldehyde and sodium hypochlorite. Comparison among cycles revealed that microhardness was significantly decreased for three cycles of microwave disinfection.

CONCLUSION

It was concluded that there was no significant difference in microhardness when the teeth were subjected to chemical disinfection but three cycles of microwave disinfection produced decrease in the microhardness of different types of artificial teeth.

Photodynamic inactivation of a multispecies biofilm using curcumin and LED light

This study evaluated the potential of curcumin-mediated antimicrobial photodynamic inactivation (API) on multispecies biofilms of Candida albicans, Candida glabrata, and Streptococcus mutans of different ages. Acrylic samples (n = 480) were made with standardized rough surfaces and incubated with bacteria and yeast for 24 or 48 h. API was performed with curcumin (80, 100, 120 μM) and LED light. Additional acrylic samples were treated with curcumin or LED light only. Positive control samples received neither light nor curcumin. After API, colony counts were quantified (CFU/mL), cell metabolism was determined by means of XTT assay, and the total biofilm biomass was evaluated using Crystal Violet (CV) staining assay and images were obtained by confocal laser scanning microscopy (CLSM). The data were analyzed by nonparametric two-way ANOVA and post hoc Tukey tests (α < 0.05). For 24-h biofilm, API resulted in statistically significant difference (ρ < 0.001) of viability of C. albicans compared with control (P-L-) for all Cur concentrations. For 48-h biofilm, API resulted in statistically significant difference (ρ < 0.001) compared with control only when Cur at 120 μM was used. API promoted statistically significant difference (ρ ≤ 0.001) in the viability of S. mutans and C. glabrata for all Cur concentrations in the two biofilm ages. In addition, API produced a statistically significant difference (ρ < 0.001) of metabolic activity and of total biomass (ρ < 0.001) of multispecies biofilms compared with control for all Cur concentrations. It can be concluded that both 24- and 48-h biofilms were susceptible to API mediated by Cur; however, 24-h biofilm was more sensitive than the 48-h biofilm.

Peel bond strength of soft lining materials with antifungal to a denture base acrylic resin

The effect of the addition of nystatin, miconazole, ketoconazole, chlorhexidine, and itraconazole into the soft lining materials Softone and Trusoft on their peel bond strength to a denture base acrylic resin was evaluated. Specimens of soft lining materials (n=7) were made without (control) or with the incorporation of antifungals at their minimum inhibitory concentrations to the biofilm of C. albicans and bonded to the acrylic resin. Peel testing was performed after immersion in distilled water at 37ºC for 24 h, 7 and 14 days. Data (MPa) were analyzed by 3-way ANOVA/Tukey-Kramer test (α=0.05) and the failure modes were classified. The addition of nystatin and ketoconazole did not affect the peel bond strength for up to 14 days. Most failures were predominantly cohesive within soft lining materials. With the exception of itraconazole, incorporating the antifungals into the soft lining materials did not result in values below those recommended for peel bond strength after 7 and 14 days of analysis.

Cytotoxicity of antimicrobial photodynamic inactivation on epithelial cells when co-cultured with Candida albicans

This study assessed the cytotoxicity of antimicrobial Photodynamic Inactivation (aPDI), mediated by curcumin, using human keratinocytes co-cultured withCandida albicans.

Effect of the addition of antimicrobial agents on Shore A hardness and roughness of soft lining materials

PURPOSE

While the incorporation of antimicrobial agents into soft denture liners has been suggested as a reliable alternative treatment for denture stomatitis, it may affect the liner's properties. The effect of addition of antimicrobial agents for the treatment of denture stomatitis on the surface roughness and Shore A hardness of soft lining materials was evaluated.

MATERIALS AND METHODS

The test groups comprised specimens (36 × 7 × 6 mm(3) ) of soft materials (Softone and Trusoft) without (control) or with incorporation of drugs (nystatin, miconazole, ketoconazole, chlorhexidine diacetate, and itraconazole). Hardness (Shore A) and roughness (Ra) were evaluated after immersion of specimens (n = 10) in distilled water at 37°C for 24 hours, 7 and 14 days. Data were analyzed by 3-way ANOVA/Tukey's test (α = 0.05).

RESULTS

After 14 days, an increase (p < 0.05) was observed in the hardness of soft materials with time for the modified specimens, except for itraconazole. Addition of drugs increased the Softone roughness only for the addition of miconazole and chlorhexidine (p < 0.05), and did not increase the roughness of Trusoft with time. Only chlorhexidine and itraconazole altered the roughness compared to the control for each material (p < 0.05).

CONCLUSIONS

The smallest changes of hardness and roughness with time in the modified groups compared to controls were observed for itraconazole groups for both materials.

Effect of antimicrobial agents incorporated into resilient denture relines on the Candida albicans biofilm

OBJECTIVE

The antimicrobial action of five drugs incorporated in temporary denture relines on the fungal biofilm was evaluated.

MATERIALS AND METHODS

A Candida albicans biofilm (SC5314) was formed on specimens (10 × 1 mm) of materials (Trusoft and Softone) modified or not (control) by the drugs (nystatin, miconazole, ketoconazole, itraconazole, and chlorhexidine diacetate). Cell viability was determined spectrophotometrically by the tetrazolium salt reduction assay (XTT) after 24 h, 48 h, and 7 and 14 days of incubation. The minimum inhibitory concentrations (MICs) were those which inhibited 90% or more of fungal growth. Fungal susceptibility was confirmed by confocal laser scanning microscopy analysis.

RESULTS

The MICs of drugs incorporated in the materials were 0.032, 0.256, 0.128, 0.256, and 0.064 g ml(-1) for nystatin, miconazole, ketoconazole, itraconazole, and chlorhexidine, respectively. Images from nystatin, chlorhexidine, and ketoconazole demonstrated no viable cells.

CONCLUSIONS

The antimicrobials incorporated in the resilient materials inhibited fungal growth during 14 days, with lower MICs for nystatin and chlorhexidine.

Linking evidence to treatment for denture stomatitis: a meta-analysis of randomized controlled trials

OBJECTIVES

The aim of this meta-analysis was to compare the efficacy of antifungal therapy with any other alternative methods used for the treatment of denture stomatitis.

DATA SOURCES

MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials and the Cochrane Database of Systematic Reviews were searched, complemented by hand searching, until the first week of January 2013.

STUDY SELECTION

Included studies consisted of randomized clinical trials published in English or French, which compared antifungals with any other alternative or placebo, used for the treatment of denture stomatitis. The remission of clinical signs of denture stomatitis, and the reduction in Candida colony counts were considered as the clinical and microbiological outcomes, respectively. Random effects models were used to conduct the statistical analyses.

RESULTS

From 233 identified articles, a total of 15 manuscripts on 14 randomized controlled trials were included in systematic review and 8 in the meta-analysis. No statistically significant difference between antifungal treatment and disinfection methods was found for both clinical (OR=0.7; 95% CI: 0.32-1.36; Z=-1.14; p=0.256) and microbiological (OR=0.8; 95% CI: 0.26-2.5; Z=-0.35; p=0.724) outcomes. The meta-analysis showed a statistically significant difference between an antifungal and a placebo for the microbiological outcome (OR=0.32; 95% CI: 0.12-0.89; Z=-2.2; p=0.028), favouring the antifungals. However, there was no statistically significant difference between antifungal and placebo for the clinical outcome (OR=0.2; 95% CI: 0.04-1.04; Z=-1.9; p=0.056).

CONCLUSIONS

Disinfection agents, antiseptic mouthwashes, natural substances with antimicrobial properties, microwave disinfection and photodynamic therapy could be suggested as an adjunct or alternative to antifungal medications in the treatment of denture stomatitis.

Effectiveness of denture cleanser associated with microwave disinfection and brushing of complete dentures: in vivo study

Complete dentures acts as a reservoir for microbial colonization, which may lead to systemic infections. Microwave irradiation has been used as an efficient method of denture disinfection. Even though current methods eliminate denture-base microorganisms, a recurrence rate of denture stomatitis (DS) is still observed among denture-wearing patients. It was hypothesized that microwave disinfection kills microorganisms but do not remove dead bacteria from the denture surface. To test this hypothesis, the biofilm found in the dentures of 10 patients with DS was evaluated. In addition, the effects of microwave irradiation plus brushing (MW+B) on the denture biofilm and the combination of denture cleanser with microwave irradiation and brushing (MW+DC+B) for the removal of denture-accumulating microorganisms were investigated. Microbiological data were analyzed statistically by nonparametric analysis (Friedman/Wilcoxon, α=0.05). MW+B and MW+DC+B were effective in reducing the rate of microorganisms (99.2% and 99.5% respectively), but without significant difference between them (p=0.553). However, it was observed that the complete removal of microorganisms from denture surface was only possible when all regimens were combined (MW+DC+B). Microwave irradiation in combination with soaking in denture cleanser and brushing effectively disinfected the dentures and removed denture biofilm.

Comparison of denture microwave disinfection and conventional antifungal therapy in the treatment of denture stomatitis: a randomized clinical study

OBJECTIVE

The aim of this study was to compare the effectiveness of denture microwave disinfection and antifungal therapy on treatment of denture stomatitis.

STUDY DESIGN

Sixty denture wearers with denture stomatitis (3 groups; n = 20 each), were treated with nystatin or denture microwave disinfection (1 or 3 times/wk) for 14 days. Mycologic samples from palates and dentures were quantified and identified with the use of Chromagar, and clinical photographs of palates were taken. Microbiologic and clinical data were analyzed with the use of a series of statistical tests (α = .05).

RESULTS

Both treatments similarly reduced clinical signs of denture stomatitis and growth on palates and dentures at days 14 and 30 (P > .05). At sequential appointments, the predominant species (P < .01) isolated was C. albicans (range 98%-53%), followed by C. glabrata (range 22%-12%) and C. tropicalis (range 25%-7%).

CONCLUSIONS

Microwave disinfection, at once per week for 2 treatments, was as effective as topical antifungal therapy for treating denture stomatitis.

Infection prevention in long-term care: a systematic review of randomized and nonrandomized trials

The purpose of this systematic review was to critically review and synthesize current evidence and the methodological quality of nonpharmacological infection-prevention interventions in long-term care (LTC) facilities for older adults. Two reviewers searched three electronic databases for studies published over the last decade assessing randomized and nonrandomized trials designed to reduce infections in older adults in which primary outcomes were infection rates and reductions of risk factors related to infections. To establish clarity and standardized reporting of findings, the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist was used. Data extracted included study design, sample size, type and duration of interventions, outcome measures reported, and findings. Two reviewers independently assessed study quality using a validated quality assessment tool. Twenty-four articles met inclusion criteria; the majority were randomized control trials (67%) in which the primary purpose was to reduce pneumonia (66%). Thirteen (54%) studies reported statistically significant results in favor of interventions on at least one of their outcome measures. The methodological clarity of available evidence was limited, placing them at potential risk of bias. Gaps and inconsistencies surrounding interventions in LTC are evident. Future interventional studies need to enhance methodological rigor using clearly defined outcome measures and standardized reporting of findings.

Ricinus communis treatment of denture stomatitis in institutionalised elderly

This study compared the effectiveness of Ricinus communis (RC) with Nystatin (NYS) and Miconazole (MIC) in the treatment of institutionalised elderly with denture stomatitis (DS). They (n = 30) were randomly distributed into three groups: MIC, NYS or RC. Clinical and mycological evaluations were performed prior to the use of the antifungal (baseline) and repeated after 15 and 30 days of treatment. The sample was clinically examined for oral mucosal conditions. Standard photographs were taken of the palate, and the oral candidiasis was classified (Newton's criteria). Mycological investigation was performed by swabbing the palatal mucosa, and Candida spp. were quantified by counting the number of colony-forming units (cfu mL⁻¹). The clinical and mycological data were analysed, respectively by Wilcoxon and Student's t-test (α = 0.05). Significant improvement in the clinical appearance of DS in the MIC and RC groups was observed between the 1st and 3rd collections (MIC - P = 0.018; RC - P = 0.011) as well as between the 2nd and 3rd collections (MIC - P = 0.018; RC - P = 0.011). Neither groups showed a statistically significant reduction in cfu mL⁻¹ at any time. Although none of the treatments decreased the cfu mL⁻¹, it was concluded that Ricinus communis can improve the clinical condition of denture stomatitis in institutionalised elderly patients, showing similar results to Miconazole.

Effect of chemical and microwave disinfection on the surface microhardness of acrylic resin denture teeth

PURPOSE

The purpose of this study was to evaluate the effect of simulated disinfections (2% glutaraldehyde, 1% sodium hypochlorite, and microwave energy) on the surface hardness of Trilux, Biocler, Biotone, New Ace, and Magister commercial artificial teeth.

MATERIALS AND METHODS

Specimens (n = 10) were made with the teeth included individually in circular blocks of acrylic resin, leaving the labial surface exposed. Cycles of simulated chemical disinfection were accomplished with the specimens immersed in the solutions at room temperature for 10 minutes, followed by tap water washing for 30 seconds and storage in distilled water at room temperature for 7 days until the next disinfection. Simulated disinfection by microwave energy was carried out in a domestic oven with 1300 W at a potency of 50% for 3 minutes with the specimens individually immersed in 150 ml of distilled water. Control (no disinfection) and the experimental groups (first and third disinfection cycles) were submitted to Knoop hardness measurements with indentations at the center of the labial tooth surface. Data were submitted to repeated measure two-way ANOVA and Tukey's test (α = 0.05).

RESULTS

Biocler, Magister, and Trilux showed lower surface microhardness when submitted to microwave. Lower microhardness for Biotone was promoted by hypochlorite, while no significant difference was shown for New Ace. The third disinfection cycle significantly decreased the tooth surface hardness only for microwave.

CONCLUSIONS

Different disinfection methods promoted different effects on the microhardness of different types of artificial teeth. Surface microhardness of the teeth was less affected by the simulated chemical disinfections when compared to microwaved specimens.

A systematic mapping review of randomized controlled trials (RCTs) in care homes

Background

A thorough understanding of the literature generated from research in care homes is required to support evidence-based commissioning and delivery of healthcare. So far this research has not been compiled or described. We set out to describe the extent of the evidence base derived from randomized controlled trials conducted in care homes.

Methods

A systematic mapping review was conducted of the randomized controlled trials (RCTs) conducted in care homes. Medline was searched for “Nursing Home”, “Residential Facilities” and “Homes for the Aged”; CINAHL for “nursing homes”, “residential facilities” and “skilled nursing facilities”; AMED for “Nursing homes”, “Long term care”, “Residential facilities” and “Randomized controlled trial”; and BNI for “Nursing Homes”, “Residential Care” and “Long-term care”. Articles were classified against a keywording strategy describing: year and country of publication; randomization, stratification and blinding methodology; target of intervention; intervention and control treatments; number of subjects and/or clusters; outcome measures; and results.

Results

3226 abstracts were identified and 291 articles reviewed in full. Most were recent (median age 6 years) and from the United States. A wide range of targets and interventions were identified. Studies were mostly functional (44 behaviour, 20 prescribing and 20 malnutrition studies) rather than disease-based. Over a quarter focussed on mental health.

Conclusions

This study is the first to collate data from all RCTs conducted in care homes and represents an important resource for those providing and commissioning healthcare for this sector. The evidence-base is rapidly developing. Several areas - influenza, falls, mobility, fractures, osteoporosis – are appropriate for systematic review. For other topics, researchers need to focus on outcome measures that can be compared and collated.

Changes in roughness of denture base and reline materials by chemical disinfection or microwave irradiation: surface roughness of denture base and reline materials

OBJECTIVE

The effect of disinfection by immersion in sodium perborate solution and microwave irradiation on surface roughness of one denture base resin (Lucitone 550 -L), 3 hard chairside reline resins (Tokuyama Rebase II-TR, New Truliner-NT, Ufi Gel hard-UH) and 3 resilient reline materials (Trusoft-T; Sofreliner-S, Dentusil-D) was evaluated.

MATERIAL AND METHODS

Thirty specimens of each material were made and divided into 3 groups: Control - not disinfected; P - daily disinfection by immersing in sodium perborate solution (3.8%); MW - microwave disinfection (6 min/650 W). Roughness measurements were made after polymerization (baseline) and after 1, 3 and 28 days. Roughness differences relative to the baseline readings were analyzed by Student's t-test (P=0.05).

RESULTS

At baseline, Trusoft showed the highest (P<0.001) mean surface roughness (3.54 µm), and its surface roughness was significantly reduced after 28 days of disinfection by immersion in sodium perborate (P=0.013). Roughness measurements of material Trusoft were not performed after microwave disinfection due to the severe alterations on the surface. In the 3 groups evaluated, changes in roughness were significant for materials Ufi Gel hard (from 0.11 to 0.26 µm; P<0.041) and New Truliner (0.19 to 0.76 µm; P<0.019). The roughness of materials Lucitone 550 (0.37 µm), Tokuyama Rebase II (0.37 µm), Sofreliner (0.49 µm) and Dentusil (0.38 µm) remained unaffected (P>0.05).

CONCLUSIONS

The roughness of the hard reline materials Ufi Gel hard and New Truliner was adversely affected by microwave disinfection, immersion in water or in sodium perborate. Microwave disinfection caused severe alterations on the surface of the resilient liner Trusoft.

The effect of long-term disinfection procedures on hardness property of resin denture teeth

OBJECTIVE

The aim of the study was to evaluate the effect of long-term disinfection procedures on the Vickers hardness (VHN) of acrylic resin denture teeth.

MATERIAL AND METHODS

Five acrylic resin denture teeth (Vipi Dent Plus-V, Trilux-T, Biolux-B, Postaris-P and Artiplus-A) and one composite resin denture teeth (SR-Orthosit-O) were embedded in heat-polymerised acrylic resin within polyvinylchloride tubes. Specimens were stored in distilled water at 37°C for 48 h. Measurements of hardness were taken after the following disinfection procedures: immersion for 7 days in 4% chlorhexidine gluconate or in 1% sodium hypochlorite (CIm and HIm group, respectively) and seven daily cycles of microwave sterilisation at 650 W for 6 min (MwS group). In the WIm group, specimens were maintained in water during the time used to perform the disinfection procedures (7 days). Data were analysed with anova followed by the Bonferroni procedure (α = 0.01).

RESULTS

Microwave disinfection decreased the hardness of all acrylic resin denture teeth (p < 0.001). Immersion for 7 days in 4% chlorhexidine gluconate or distilled water had significant effect on the hardness of the acrylic resin denture teeth A (p < 0.01), and 1% sodium hypochlorite on teeth T (p < 0.01). All disinfection procedures decrease the hardness of the composite resin denture teeth (p < 0.01). Teeth O exhibited the highest and teeth V the lowest hardness values in the control group (p < 0.01).

CONCLUSIONS

Disinfection procedures changed the hardness of resin denture teeth.

A conventional microwave oven for denture cleaning: a critical review

INTRODUCTION

Denture cleaning should be quick and easy to perform, especially in long-term care facilities. The lack of proper oral hygiene can put older adults at higher risk from opportunistic oral infections, particularly fungal. As an alternative to regular brushing, the use of a microwave oven has been suggested for cleaning and disinfecting dentures.

OBJECTIVES

To synthesise and discuss the advantages and disadvantages of the use of a conventional microwave oven for cleaning and disinfecting complete dentures.

METHODS

A brief literature search focused on papers dealing with microwave therapy for denture cleaning through PubMed Central, Cochrane Database of Systematic Reviews, Google Scholar, Ovid MEDLINE(R) In-Process, and Scifinder Scholar.

RESULTS

One hundred and sixty-seven manuscripts published in English with full text were found, and 28 were accepted and discussed in the light of the advantages and disadvantages of the use of conventional microwave oven for cleaning and disinfecting complete dentures.

CONCLUSIONS

There was no standardisation for microwave use for denture cleaning. Manual cleaning still seemed to be the optimal method for controlling fungal infection and denture stomatitis. However, such a daily routine appeared to be underused, particularly in long-term care facilities.

Photodynamic inactivation of four Candida species induced by photogem(®)

This study evaluated the in vitro susceptibility of C. albicans, C. dubliniensis, C. tropicalis and C. krusei to photodynamic therapy (PDT) induced by Photogem^®and light emitted diode (LED). Suspensions of each Candida strain were treated with three photosensitizer (PS) concentrations (10, 25 and 50 mg/L) and exposed to 18, 25.5 and 37.5 J/cm² LED light fluences (λ ~ 455 nm). Control suspensions were treated only with PS concentrations, only exposed to the LED light fluences or not exposed to LED light or PS. Sixteen experimental conditions were obtained and each condition was repeated three times. From each sample, serial dilutions were obtained and aliquots were plated on Sabouraud Dextrose Agar. After incubation of plates (37 °C for 48 hours), colonies were counted (cfu/mL) and the data were statistically analyzed by ANOVA and the Tukey test (α=0.05). Complete killing of C. albicans was observed after 18 J/cm² in association with 50 mg/L of PS. C. dubliniensis were inactivated after 18 J/cm² using 25 mg/L of PS. The inactivation of C. tropicalis was observed after photosensitization with 25 mg/L and subsequent illumination at 25.5 J/cm². For C. krusei, none of the associations between PS and light resulted in complete killing of this species. PDT proved to be effective for the inactivation of C. albicans, C. dubliniensis and C. tropicalis. In addition, reduction in the viability of C. krusei was achieved with some of the PS and light associations.

Denture disinfection by microwave irradiation: a randomized clinical study

OBJECTIVE

This study evaluated the clinical effectiveness of two exposure times of microwave irradiation on the disinfection of complete dentures.

METHODS

Biofilm samples were collected from dentures of 30 patients, who were randomly divided into two experimental groups of 15 subjects each: Group 1-patients had their maxillary denture microwaved for 3 min (650W); Group 2-patients had their maxillary denture microwaved for 2 min (650W). Denture biofilm samples were taken with swabs, before (left side surfaces) and after (right side surfaces) microwave irradiation. All microbial material was plated on selective media for Candida spp., Staphylococcus spp., mutans streptococci and a non-selective media. After incubation (48 h/37 degrees C), the number of colony-forming units (cfu/mL) was counted. Microorganisms which grew on selective media were identified using biochemical methods. The data were statistically analyzed by Kruskal-Wallis test, followed by Dunn's post-test (alpha=0.05).

RESULTS

Microwave irradiation for 3 min (Group 1) resulted in sterilization of all dentures evaluated. After microwave irradiation for 2 min (Group 2), a significant decrease in Candida spp. (P=0.0062), Staphylococcus spp. (P=0.0178), mutans streptococci (P=0.0047) and non-identified species (P<0.0001) was achieved in comparison with the cfu/mL obtained before irradiation. The colonies grown after 2 min of microwave irradiation were identified as Candida albicans, non-aureus Staphylococci and Streptococcus mutans.

CONCLUSION

Microwave irradiation for 3 min may be a potential treatment to prevent cross-contamination.

Effectiveness of microwave disinfection of complete dentures on the treatment of Candida-related denture stomatitis

The effectiveness of microwave disinfection of maxillary complete dentures on the treatment of Candida-related denture stomatitis was evaluated. Patients (n = 60) were randomly assigned to one of four treatment groups of 15 subjects each;

CONTROL GROUP

patients performed the routine denture care; Mw group: patients had their upper denture microwaved (650 W per 6 min) three times per week for 30 days; group MwMz: patients received the treatment of Mw group in conjunction with topical application of miconazole three times per day for 30 days; group Mz: patients received the antifungal therapy of group MwMz. Cytological smears and mycological cultures were taken from the dentures and the palates of all patients before treatment at day 15 and 30 of treatment and at follow-up (days 60 and 90). The effectiveness of the treatments was evaluated by Kruskal-Wallis and Mann-Whitney tests. Microbial and clinical analysis of the control group demonstrated no significant decrease in the candidal infection over the clinical trial. Smears and cultures of palates and dentures of the groups Mw and MwMz exhibited absence of Candida at day 15 and 30 of treatment. On day 60 and 90, few mycelial forms were observed on 11 denture smears (36.6%) from groups Mw and MwMz, but not on the palatal smears. Miconazole (group Mz) neither caused significant reduction of palatal inflammation nor eradicated Candida from the dentures and palates. Microwaving dentures was effective for the treatment of denture stomatitis. The recurrence of Candida on microwaved dentures at follow-up was dramatically reduced.

Effect of different exposure times on microwave irradiation on the disinfection of a hard chairside reline resin

PURPOSE

This study evaluated the effectiveness of different exposure times of microwave irradiation on the disinfection of a hard chairside reline resin.

MATERIALS AND METHODS

Sterile specimens were individually inoculated with one of the tested microorganisms (Pseudomonas aeruginosa, Staphylococcus aureus, Candida albicans, and Bacillus subtilis) and incubated for 24 hours at 37 degrees C. For each microorganism, 10 specimens were not microwaved (control), and 50 specimens were microwaved. Control specimens were individually immersed in sterile saline, and replicate aliquots of serial dilutions were plated on selective media appropriate for each organism. Irradiated specimens were immersed in water and microwaved at 650 W for 1, 2, 3, 4, or 5 minutes before serial dilutions and platings. After 48 hours of incubation, colonies on plates were counted. Irradiated specimens were also incubated for 7 days. Some specimens were prepared for scanning electron microscopic (SEM) analysis.

RESULTS

Specimens irradiated for 3, 4, and 5 minutes showed sterilization. After 2 minutes of irradiation, specimens inoculated with C. albicans were sterilized, whereas those inoculated with bacteria were disinfected. One minute of irradiation resulted in growth of all microorganisms. SEM examination indicated alteration in cell morphology of sterilized specimens. The effectiveness of microwave irradiation was improved as the exposure time increased.

CONCLUSION

This study suggests that 3 minutes of microwave irradiation can be used for acrylic resin sterilization, thus preventing cross-contamination.