The aim of this study was to quantify biofilm on the internal surface of upper complete dentures following six possible cleansing methods. Thirty-six edentulous subjects were submitted to a time-series trial and dentures were cleansed according to six methods: (i) rinsing with water; (ii) soaking in an alkaline peroxide solution (Bonyplus); (iii) brushing with dentifrice (Dentu-Creme) and soft Johnson and Johnson's toothbrush; (iv) combination between soaking and brushing according to methods 2 and 3; (v) brushing with dentifrice (Dentu-Creme) and soft Oral B toothbrush; (vi) combination between soaking and brushing according to methods 2 and 5. Each method was randomly used throughout 21 days. Denture biofilm was disclosed by 1% neutral red solution and quantified by means of digital photos taken from the internal surface. The six methods presented significant differences in percentage of biofilm coverage (repeated measures anova, P < 0.0001). Method 1 showed the highest values, 2 was intermediate and other results were the lowest. The most efficacious approach was 6. Biofilm tended to accumulate predominantly over specific zones of the denture base, but this pattern did not change regardless of the method employed. It can be concluded that brushing alone was more effective than the chemical method employed. The best results were obtained by a combination of methods.

Although the color changes after the immersion in denture cleansers were clinically insignificant, the Corega Tabs group showed higher color differences. The Bony Plus group showed significantly increased surface roughness. Both effervescent tablets Corega Tabs and Bony Plus significantly diminished the flexural strength of the acrylic resin.

This study evaluated color stability, surface roughness and flexural strength of acrylic resin specimens after immersion in alkaline peroxide and alkaline hypochlorite, simulating a period of one and a half year of use of overnight immersion. Sixty disc-shaped (16x4 mm) and 80 rectangular specimens (65x10x3.3 mm) were prepared from heat-polymerized acrylic resin (Lucitone 550) and distributed into 4 groups (n=20): C1: without immersion, C2: 8 h immersion in distilled water; AP: 8 h immersion in alkaline peroxide effervescent tablet; SH: 8 h immersion in 0.5% NaOCl solution. Properties were evaluated at baseline and after the immersion. Color data were also calculated according the National Bureau of Standards (NBS). Results were analyzed statistically by ANOVA and Tukey's HSD test (α=0.05). AP (2.34 ± 0.41) caused color alteration significantly higher than C2 (0.39 ± 0.30) and SH (1.73 ± 0.52). The mean ΔΕ values were classified as indicial for C2 (0.36 ± 0.29) and noticeable for AP (2.12 ± 0.39) and SH (1.59 ± 0.48). SH (0.0195 ± 0.0150) caused significantly higher ΔRa (p=0.000) than the C2 (0.0005 ± 0.0115) and PA (0.0005 ± 0.0157) groups. There was no statistically significant difference (p=0.063) among the solutions for flexural strength (C1: 105. 43 ± 14.93, C2: 100.30 ± 12.43, PA: 97.61 ± 11.09, SH: 95.23 ± 10.18). In conclusion, overnight immersion in denture cleansing solutions simulating a year and a half of use did not alter the flexural strength of acrylic resin but caused noticeable color alterations, higher for alkaline peroxide. The 0.5% NaOCl solution caused increase in surface roughness.

In this study, a questionnaire was applied to patients from Ribeirão Preto Dental School, University of São Paulo, Brazil, to evaluate the hygiene methods and habits concerning the use of complete dentures, the age of dentures, and whether patients have been instructed on how to clean their dentures. The mean age of patients was 63.35 years, and most of them were females (82.08%). The results showed that 62.26% of the respondents had been using the same maxillary complete denture for more than 5 years, and 49.06% used the same mandible complete denture for more than 5 years. Of the patients interviewed, 58.49% slept with the dentures. Mechanical brushing was the most used cleaning method by the patients (100%), using water, dentifrice and toothbrush (84.91%). Most patients (51.89%) reported never having been instructed by their dentists as to how to clean their dentures. Based on the limitations of this study, it was concluded that the patients interviewed had limited knowledge about prosthetic hygiene and oral care. The method more used by patients was the mechanical method of brushing, most patients used the same complete dentures for more than 5 years and slept with the dentures.

Removable partial dentures (RPD) demand specific hygienic cleaning and the combination of brushing with immersion in chemical solutions has been the most recommended method for control of biofilm. However, the effect of the cleansers on metallic components has not been widely investigated. This study evaluated the effect of different cleansers on the surface of RPD. Five disc specimens (12 mm x 3 mm metallic disc centered in a 38 x 18 x 4 mm mould filled with resin) were obtained for each experimental situation: 6 solutions [Periogard (PE), Cepacol (CE), Corega Tabs (CT), Medical Interporous (MI), Polident (PO), 0.05% sodium hypochlorite (NaOCl), and distilled water (DW) control] and 2 Co-Cr alloys [DeguDent (DD) and VeraPDI (VPDI)] were used for each experimental situation. A 180-day immersion was simulated and the measurements of roughness (Ra, µm) of metal and resin were analyzed using 2-way ANOVA and Tukey's test. The surface changes and tarnishes were examined with a scanning electronic microscopy (SEM). In addition, energy dispersive x-ray spectrometry (EDS) analysis was carried out at representative areas. Visually, NaOCl and MI specimens presented surface tarnishes. The roughness of materials was not affected by the solutions (p>0.05). SEM images showed that NaOCl and MI provided surface changes. EDS analysis revealed the presence of oxygen for specimens in contact with both MI and NaOCl solutions, which might suggest that the two solutions promoted the oxidation of the surfaces, thus leading to spot corrosion. Within the limitations of this study, it may be concluded that the NaOCl and MI may not be suitable for cleaning of RPD.

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.

There is a lack of evidence about the comparative effectiveness of the different denture cleaning methods considered in this review. Few well designed RCTs were found. Future research should focus on comparisons between mechanical and chemical methods; the assessment of the association of methods, primary variables and costs should also receive future attention.

It can be concluded that brushing complete dentures with the experimental dentifrices tested could be effective for the removal of denture biofilm.