Cláudia Helena Lovato da Silva

Effect of denture cleansers on physical properties of heat-polymerized acrylic resin

PURPOSE This study aimed to measure the color change, surface roughness and flexural strength of heat-polymerized acrylic resin after its immersion in denture cleansers, simulating a 180-day use. METHODS Thirty disk-shaped (15mm x 4mm) and 30 rectangular samples (65mm x 10mm x 3.3mm) were prepared from heat-polymerized acrylic resin and immersed in Corega Tabs, Bony Plus, and distilled water. Color measurements (DeltaE) were determined by a portable colorimeter. A surface analyzer was used to measure the roughness before and after immersion (DeltaRa). The flexural strength (S) was measured using a 3-point bending test. The DeltaE values were submitted to statistical analysis by the Kruskal-Wallis test, followed by Dunns Multiple Comparisons test. The DeltaRa and S values were submitted to statistical analysis by ANOVA, followed by a Student-Newman-Keuls test (alpha=.05). RESULTS The color changes were significantly higher for the Corega Tabs than for the control group. The mean DeltaE values quantified by the National Bureau of Standards (NBS) were classified as Trace (0.0-0.5). The Bony Plus group had significantly higher surface roughness than the other groups. Corega Tabs and Bony Plus groups presented lower flexural strength than the control group. CONCLUSIONS 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.

Behaviors and hygiene habits of complete denture wearers

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.

Effect of the physical properties of acrylic resin of overnight immersion in sodium hypochlorite solution.

OBJECTIVES This study evaluated colour stability, surface roughness and flexural strength of microwave-polymerised acrylic resin after overnight immersion in sodium hypochlorite, simulating 180 days use. MATERIALS AND METHODS Forty disc-shaped (15 mm x 4 mm) and 40 rectangular specimens (65 mm x 10 mm x 3 mm) were prepared from microwave-polymerised acrylic resin. The specimens were immersed in 0.5, 1% sodium hypochlorite, Clorox/Calgon and distilled water. Colour measurements (ΔE) were determined by a portable colorimeter. A surface analyser was used to measure roughness (μm). The flexural strength (MPa) was measured using a three-point bending test in a universal testing machine. Data were evaluated by one-way anova, followed by Student-Newman-Keuls test (α = 0.05). RESULTS Statistical analysis found significantly higher colour changes (SNK, p < 0.001) for the 1% sodium hypochlorite, but mean ΔE value quantified by National Bureau of Standards was classified as slight. When comparing the surface roughness, no statistical significance was found among the solutions (anova, p = 0.637). The 1% sodium hypochlorite presented significantly lower flexural strength compared with the control group (SNK, p = 0.034). CONCLUSION It was concluded that immersion in 1% sodium hypochlorite solutions for 8 h does influence the colour stability and flexural strength of microwave-polymerised acrylic resin, during the simulated period of 180 days.

In vitro and clinical evaluation of specific dentifrices for complete denture hygiene.

OBJECTIVES To study the physical properties of two experimental dentifrices for complete denture hygiene, their effect on denture biofilm removal and antimicrobial properties by means of a clinical trial. MATERIALS AND METHODS The experimental dentifrices comprised two compositions. One was based on the addition of 1% chloramine T (D1) and the other on the presence of 0.01% fluorosurfactant (D2). Measurements of density, pH, consistency, rheological features and abrasiveness were conducted. Sixty complete denture wearers were randomly assigned to three groups and were instructed to brush their dentures with a specific toothbrush: (1) Water (control); (2) D1; or (3) D2. Each method was used for 21 days. Denture biofilm was disclosed by a 1% neutral red solution and quantified by means of digital photos taken from the internal surface. Microbiological assessment was conducted to quantify Candida sp. and mutans streptococci. Data were evaluated by one-way anova and Tukey HSD, or Kruskal-Wallis (alpha = 0.05). RESULTS Both dentifrices decreased biofilm coverage when compared with the control group. D1 was the most efficacious treatment to reduce mutans streptococci, whereas D2 showed an intermediate outcome (ANOVA, p < 0.040). No treatment influenced Candida albicans or non-albicans species (Kruskal-Wallis, p = 0.163 and 0.746, respectively). CONCLUSION It can be concluded that brushing complete dentures with the experimental dentifrices tested could be effective for the removal of denture biofilm.

Evidenciadores de biofilme em prótese total: avaliação clínica e antimicrobiana

This study evaluated the disclosing ability, removal facility and antimicrobial effect of biofilm disclosing agents applied on complete dentures. Disclosing ability was evaluated by means of the visual method. The solutions were applied on the internal surface of dentures. After being photographed, the dentures were brushed with denture-specific brush and dentifrice and photographed again. The obtained slides were projected on paper (10 X amplification) and the total and stained surfaces were outlined with graphite, cut off and weighed, in order to assess removal facility. The evaluation of antimicrobial effects was carried out by means of the method of diffusion in agar, and the results were obtained by measuring the length of the halos and rings. In terms of disclosing ability, the best solutions were 0.05% methylene blue, 5% erythrosin, 1% sodic fluorescein, Replak and 1% neutral red. One percent eosin, 1% sodic fluorescein and 5% erythrosin were the most easily removed solutions. One percent eosin, 5% erythrosin, 1% sodic fluorescein, 0.3% proflavine, Replak and 1% neutral red presented no antimicrobial effect. The solutions which presented the greatest disclosing ability and removal facility as well as absence of antimicrobial effect - which are essential requirements in the assessment of hygiene methods and guidance on oral health - were 1% eosin, 1% neutral red and 5% erythrosin.

Effervescent tablets and ultrasonic devices against Candida and mutans streptococci in denture biofilm.

OBJECTIVE To evaluate the antimicrobial action of effervescent tablets and ultrasound on Candida spp. and mutans streptococci from denture biofilm. BACKGROUND It is not uncommon for edentulous patients to be elderly and find it difficult to brush their dentures. Hence, auxiliary methods are required for cleansing dentures as well as treating oral infections. MATERIALS AND METHODS Seventy-seven complete denture wearers were randomly assigned into four groups: (A) Brushing with water (control); (B) Effervescent tablets; (C) Ultrasonic device (Ultrasonic Cleaner, model 2840 D); (D) Effervescent tablets and ultrasonic device. All groups brushed their dentures with a specific brush and water, three times a day, before applying their treatments. Denture biofilm was collected at baseline and after 21 days. The samples were collected by brushing the dentures with saline and the detached microbial cells were quantified by plating. Counts [log (CFU+1) ml(-1) ] of total aerobes, Candida spp. and mutans streptococci were compared by one-way anova or Kruskal-Wallis test (α = 0.05). RESULTS No significant difference was found among the methods from C. albicans (p = 0.76), C. tropicalis (p = 0.94) and C. glabrata (p = 0.80). Lower counts were found for methods B and D when compared with the other methods against mutans streptococci (p < 0.001). Method B showed lower total aerobic counts than A, whereas C and D showed intermediate results (p = 0.011). CONCLUSION The effervescent tablets significantly reduced mutans streptococci and total aerobes from denture biofilm. However, they was not as effective against C. albicans. Ultrasonic cleansing presented a discrete antimicrobial effect and was less effective than the tablets for complete denture disinfection.

Efficacy of biofilm disclosing agent and of three brushes in the control of complete denture cleansing

Objective: This report evaluated the efficacy of three brushes and one biofilm disclosing agent in complete denture cleansing. Methods: Twenty-seven wearers of maxillary dentures were distributed into three groups and received different brushes: Oral B40, conventional toothbrush (Oral B); Denture, denture-specific brush (Condor); Johnson & Johnson, denture-specific brush (Johnson & Johnson). The 60-day experimental period was divided into two techniques: I - brushing (brush associated with a paste - Dentu Creme, Dentco) three times a day; II - brushing and daily application of 1% neutral red on the denture internal surface. Biofilm quantification was carried out weekly and the areas with dye biofilm were obtained by means of Image Tool 2.02 software. Results: Biofilm removal was more effective during Technique II (Wilcoxon test: p=0.01) for the three groups of brushes. When the brushes were compared in Technique I, the Kruskal Wallis test indicated statistical difference between Denture X Johnson & Johnson and Denture X Oral B40, in which the Denture was more efficient. For Technique II, there was no statistical difference between brushes (p>0.05). Conclusion: The disclosed application promoted more efficacy on biofilm removal, regardless of the brush used. Denture (Condor) was more efficient than the other brushes during Technique I.

Comparative study of methods for the quantification of biofilm on complete dentures

This study compared the application and reliability of 4 methods for biofilm quantification (computerized, paper-weighing, point-counting, and planimetric) in complete dentures, verifying the correlation between them. The internal surfaces of 62 complete dentures were stained (5% erythrosine) and photographed. The slides were projected on paper, and the areas (total and biofilm-covered) were outlined with a pencil. These areas were measured with an equidistant point grid (point-counting method), a digital planimeter (planimetric method), and for the paper weighing method they were cut and weighed with a precision scale. For the computerized method, ImageTool software was used. In order to perform a validation test of the methods, all of them were applied to slide projections of geometric figures with known dimensions. The correlation tests showed high correlation values (r = 0.82 to 0.99) among the methods. The validation test (ANOVA) showed no statistically significant differences among the values obtained from the measurement of figures using all four quantitative methods and the real dimensions of these geometric figures. Quantitative methods were efficient and reliable for measuring quantity of biofilm in complete dentures, and may be useful in experimental studies on the efficacy of hygiene products. The computerized method was fast and easy to perform.

Effect of experimental Ricinus communis solution for denture cleaning on the properties of acrylic resin teeth

This study evaluated Knoop hardness, surface roughness and color alteration of artificial teeth for dentures after immersion in water, 1% sodium hypochlorite and an experimental solution of 2% Ricinus communis (RC). Thirty specimens of Vipi, Biolux and Trilux were analyzed. Tests of Knoop hardness, surface roughness and color alteration were conducted immediately after specimen preparation (T0) and after two immersion protocols for 15 days (ΔT(15)) and 183 days (ΔT(183)). Data variation (ΔT) were subjected to ANOVA and Tukeys test (p<0.05). At ΔT(15), Vipi presented hardness increase and Biolux presented the highest variation (p=0.01). RC caused the highest increase in hardness (p=0) and the lowest increase (p=0.005) in roughness. Biolux presented the lowest color alteration (p =0). At ΔT(183), Trilux underwent the highest hardness variation (p=0). Biolux presented an increase in roughness (p=0). There was no significant differences in color alteration among the artificial teeth (p=0.06) and among solutions (p=0.08) after 183 days of immersion. All solutions (distilled water, 1% sodium hypochlorite and 2% RC) caused alterations on the analyzed properties. Both immersion protocols caused alterations on the analyzed properties.

Evaluation of experimental cleanser solution of Ricinus communis: effect on soft denture liner properties

OBJECTIVE This study evaluated colour stability, hardness and roughness of soft denture liners after immersion in various cleansers. MATERIALS AND METHODS Thirty specimens (14 mm × 4 mm) of Elite Soft Relining (ES) and Mucopren Soft (MS) were randomly immersed in distilled water at 37°C, sodium hypochlorite 1%, and an experimental Ricinus communis solution (RC) for 7, 15 and 183 continuous days. RESULTS anova (p < 0.05) and Tukeys test indicated that after T7 (μ =8.79 ± 7.36); T15 (μ = 4.23 ± 2.62) and T183 (μ = 8.78 ± 3.16), MS presented a higher increase in hardness than ES. After T7, MS underwent an increase in roughness (μ = 0.09 ± 0.80); ES underwent a decrease (μ = -0.08 ± 0.16). RC caused the smallest variation in roughness. After T15, both materials presented an increase in roughness. After T183, ES (μ = -0.30 ± 0.48) presented a higher roughness variation than MS (μ = -0.07 ± 0.32). Hypochlorite caused an increase in roughness (μ = 0.02 ± 0.19). CONCLUSION After all periods ES presented higher colour alteration than MS; highest colour alteration was caused by hypochlorite. Both materials were more stable after immersion in RC.