Microbiological evaluation of an experimental denture cleanser containing essential oil of Lippia sidoides

Natural products for denture base disinfection: A scoping review

OBJECTIVE

This study aims to map the existing literature on natural products used as disinfection substances for conventional polymethyl methacrylate (PMMA) and computer-aided design and manufacturing (CAD-CAM) dentures.

BACKGROUND

Denture wearers are at high risk for denture stomatitis. Natural products have attracted the interest of the scientific community as an alternative to synthetic ones.

MATERIALS AND METHODS

The guiding question "Which natural products have been applied to disinfect complete dentures in conventional PMMA or CAD-CAM PMMA resin?" Searches were conducted in the PubMed/MEDLINE, Embase, Web of Science, and Cochrane databases, and manual searches were performed in reference journals in the area with studies published until December 2023, without language or date restrictions.

RESULTS

A total of 4272 articles were identified, and 46 studies were included after applying the eligibility criteria. Thirty-nine natural products were evaluated. Of the included studies, 43 presented positive findings and three obtained negative findings on the effectiveness of natural products in inhibiting or killing Candida albicans.

CONCLUSION

Natural products, predominantly sourced from the Plantae kingdom, have demonstrated efficacy in reducing Candida albicans on the surface of conventional PMMA. However, the evidence primarily stems from in vitro studies, underscoring the necessity for additional clinical research to validate their applicability under real microbiological conditions in prosthesis users.

Effect of sanitizing solutions on cobalt chromium alloys for dental prostheses: A systematic review of in vitro studies

STATEMENT OF PROBLEM

Given the wide use of cobalt chromium (Co-Cr) alloys, especially for removable partial dentures, and the importance of chemical solutions to complement the cleaning of dental prostheses, safe disinfection products should be identified for the regular decontamination of Co-Cr dental prostheses.

PURPOSE

The purpose of this systematic review of in vitro studies was to determine the effects on the properties of Co-Cr dental alloys of the various chemical agents used to clean dental prostheses.

MATERIAL AND METHODS

In vitro studies were included based on a literature search conducted in March 2022 in the Medline/PubMed, SCOPUS, Web of Science, Virtual Health Library, and Embase databases. Independent reviewers performed the search, selection, extraction, and analysis of the data. The review was performed based on the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines. The quality of the included articles was evaluated by using parameters adapted from the Consolidated Standards of Reporting Trials (CONSORT) guidelines, and the risk of bias analysis was performed based on previous studies.

RESULTS

Among the 15 included studies, the chemical agents evaluated were alkaline peroxides and hypochlorites, mouthwashes containing cetylpyridinium chloride and chlorhexidine, diluted acids, and enzymes. Some peroxides produced increased ion release, surface roughness, and mass loss of the alloys. The hypochlorites were responsible for the greatest surface corrosion, yielding dark stains, rough regions, and depressions. Acetic and peracetic acids and mouthwashes containing chlorhexidine and cetylpyridinium did not produce significant changes in Co-Cr alloys. Most studies presented moderate risk of bias.

CONCLUSIONS

According to the included studies, mouth rinses containing cetylpyridinium chloride or chlorhexidine and solutions with acetic and peracetic acid could be safely used to chemically sanitize Co-Cr prostheses. Alkaline peroxides should be used with caution, and alkaline hypochlorite solutions should be avoided.

Surface Modifications and Antifungal Efficacy of Origanum Oil Incorporation in Denture-based Materials: An In Vitro Study

AIM

This study aimed to assess if the addition of origanum oil to denture materials could decrease microorganisms counts and biofilm formation without changing their mechanical/surface properties.

MATERIALS AND METHODS

A total of 66 resilient denture liner discs (SoftConfort, Dencril Comércio de Plásticos Ltda, SP, Brazil) were prepared with fixed dimensions of 10 × 3 mm for biofilm assay (n = 36) and 12 × 2 mm for sorption-solubility tests (n = 30) containing three oil concentrations - 0, 2.5 and 5%, thereby n = 12 per each group samples for biofilm assay and n = 10 per each group for sorption-solubility test respectively. While the microcosm biofilms of Streptococcus mutans, Candida species, and total microorganisms formed on denture liner were counted and expressed as colony-forming units per disc surface area, the water sorption (WS) and solubility (SL), was calculated by weighing the samples with an analytical balance at different intervals after storing them in a desiccator and distilled water alternatively. Data was recorded and statistically analyzed.

RESULTS

Surface roughness increased in all groups after biofilm formation (p < 0.001), with the most significant change observed in the 2.5% oil group. The tested oil concentrations did not result in sorption changes, but a 5% oil concentration resulted in higher solubility (p < 0.001). A reduction of total microorganisms and S. mutans was seen after 24 hours for all concentrations (p < 0.05). No significant reduction was found for Candida (C.) albicans after 24 hours, whilst 2.5% oil concentration presented lower counts of C. albicans in comparison to the 5% group after 24 hours (p < 0.05).

CONCLUSIONS

Incorporating 2.5% origanum essential oil into resilient denture liners seems to reduce microorganisms count in a complex biofilm model. These results need to be confirmed in future studies.

CLINICAL SIGNIFICANCE

The addition of natural products like origanum oil into denture-based materials can help manage biofilm onset and development while offering a simple and effective approach for maintaining denture hygiene. This strategy enhances the antimicrobial properties of denture liners without significantly altering their mechanical and surface characteristics, potentially improving patient outcomes. How to cite this article: Feitosa MÁL, Poletto-Neto V, Maske TT, et al. Surface Modifications and Antifungal Efficacy of Origanum Oil Incorporation in Denture-based Materials: An In Vitro Study. J Contemp Dent Pract 2024;25(9):878-884.

Biofilm inhibition of denture cleaning tablets and carvacrol on denture bases produced with different techniques

OBJECTIVES

This study compares the biofilm inhibition effects of denture cleaning tablets, carvacrol, and their combined use against Candida albicans on denture bases produced with different techniques. Additionally, the surface roughness and contact angles of these denture bases were evaluated.

MATERIALS AND METHODS

Test samples were prepared from four different denture base materials (cold-polymerized, heat-polymerized, CAD/CAM milling, and 3D-printed). The surface roughness and contact angles of the test samples were measured using a profilometer and goniometer, respectively. For the evaluation of biofilm inhibition, samples were divided into 5 subgroups: Corega and carvacrol, separately and combined treatments, positive (inoculated with C. albicans) and negative control (non-inoculated with C. albicans, only medium). Biofilm mass was determined using the crystal violet method. An additional prepared test sample for each subgroup was examined under scanning electron microscopy (SEM).

RESULTS

The surface roughness values of the 3D-printed test samples were found to be statistically higher than the other groups (P < .001). The water contact angle of all test materials was not statistically different from each other (P > .001). Corega and carvacrol, separately and combined, significantly decreased the amount of biofilm on all surfaces (P < .0001). Treatment of corega alone and in combination with carvacrol to the 3D-printed material caused less C. albicans inhibition than the other groups (P < .001; P < .05).

CONCLUSIONS

The surface roughness values of all test groups were within the clinically acceptable threshold. Although Corega and carvacrol inhibited C. albicans biofilms, their combined use did not show a synergistic effect.

CLINICAL RELEVANCE

Carvacrol may be used as one of the disinfectant agents for denture cleaning due to its biofilm inhibition property.

Antimicrobial activity of essential oils against biofilms formed in dental acrylic resin: a systematic review of in vitro studies

This study aimed to answer the question formulated according to the PICO strategy: 'Which essential oils show antimicrobial activity against biofilms formed on dental acrylic resin?' composed by population (dental acrylic resin), intervention (application of essential oils), comparison (denture cleansers, antifungal drugs, chlorhexidine, and oral mouthwashes), and outcome (antibiofilm activity). In vitro experimental studies evaluating the activity of EOs on biofilm formed on acrylic resin were included. PRISMA guidelines were followed, and the search was performed in the PubMed, Science Direct, Embase, and Lilacs databases and in the gray literature using Google Scholar and ProQuest in December 2023. A manual search of the reference lists of the included primary studies was performed. Of the 1467 articles identified, 37 were selected for full-text reading and 12 were included. Twelve EOs were evaluated, of which 11 showed activity against Candida spp., 3 against Staphylococcus aureus, and 1 against Pseudomonas aeruginosa. The EOs of Cymbopogon citratus, Cinnamomum zeylanicum, and Cymbopogon nardus showed higher action than chlorhexidine, C. nardus higher than Listerine, C. citratus higher than nystatin, and Melaleuca alternifolia higher than fluconazole and nystatin. However, chlorhexidine was more effective than Lippia sidoides and Salvia officinalis, sodium hypochlorite was more effective than L. sidoides, nystatin was more effective than Zingiber officinale, Amphotericin B more effective than Eucalyptus globulus and M. alternifolia. In conclusion, the EOs of C. zeylanicum, C. citratus, C. nardus, and M. alternifolia showed antimicrobial activity to reduce biofilm on dental acrylic resin.

A Systematic Review of the Potential Effects of Lippia sidoides on Dental Plaque and Periodontal Diseases

Lippia sidoides is a typical shrub from Brazil that has been used in traditional medicine. This is a systematic review on the effect of L. sidoides for controlling dental plaque, gingivitis, and periodontitis. A database search through May 2021 in Medline/PubMed, SCOPUS, BVS, and Web of Science identified 711 reports of which 17 met our inclusion criteria. Five randomized controlled trials and three animal studies were included that compared L. sidoides-based products (toothpaste, mouthrinse, and gel) to cetylpyridinium chloride, chlorhexidine, and placebo products. Among the human studies, a significant antiplaque effect after treatment with L. sidoides-based products was observed in three studies and an antigingivitis effect in two studies, similar to chlorhexidine-based products. One study found superior dental plaque reduction compared to cetylpyridinium chloride mouthrinse. Only one study testing a L. sidoides gel found no antiplaque effect. Among the animal studies, an L. sidoides mouthrinse significantly reduced calculus in two studies, inflammatory infiltrate in one study, and plaque bacteria and gingivitis in one study. An L. sidoides gel significantly reduced alveolar bone loss and inflammatory response in one study in which mice were submitted to ligature-induced periodontal disease. In general, L. sidoides-based products were effective in reducing dental plaque and calculus formation, as well as clinical signs of gingivitis. As most studies present methodological limitations, these results should be interpreted carefully. Further clinical trials with greater methodological accuracy and control of biases are necessary for the use of L. sidoides-based products in humans to be viable in clinical practice.

Nanostructured Lipid Carriers Loaded with Lippia sidoides Essential Oil as a Strategy to Combat the Multidrug-Resistant Candida auris

The emerging pathogen Candida auris is an emerging fungal pathogen that was associated with nosocomial infectious outbreaks. Its worldwide incidence and the emerging multidrug-resistant strains highlight the urgency for novel and effective antifungal treatment strategies. Lippia sidoides essential oil (LSEO) proved antifungal activity, including anti-Candida. However, it may undergo irreversible changes when in contact with external agents without adequate protection. Herein, we encapsulated LSEO in nanostructured lipid carriers (NLC) through the hot emulsification method followed by sonication. NLC matrix was based on oleic acid and Compritol^® 888, or a combination of carnauba wax and beeswax, stabilized by sodium dodecyl sulfate. Eight formulations were produced and characterized by the determination of the particle size (213.1 to 445.5 nm), polydispersity index (around 0.3), and ζ-potential (−93.1 to −63.8 mV). The antifungal activity of nanoparticles and LSEO against C. auris and the in vivo toxicity in Galleria mellonella model were also evaluated. Both NLC and LSEO exhibited potent activity against the yeast, with Minimum Inhibitory Concentration between 281 and 563 µg/mL, and did not evidence toxicity in the in vivo model. Therefore, this study confirms the viability of NLCs loaded with LSEO in combating drug-resistant pathogens as a potential new therapeutic strategy for managing of candidemia.