Effects of simulated long-term exposure to bottled, neutral pH electrolyzed oxidizing water on the properties of denture base resins.

STATEMENT OF PROBLEM: Denture stomatitis can pose serious health risks, especially to older people. Chemical denture cleaning agents must be effective, yet not adversely affect the longevity of removable dentures. Ready-to-use (RTU) neutral pH electrolyzed oxidizing water (EOW) is an effective biocide against Candida albicans biofilms on denture resins, but the effects of daily disinfection with EOW on the physical and mechanical properties of resins have not been established. PURPOSE: The purpose of this in vitro study was to investigate the effects of simulated long-term exposure to RTU EOW on the color, surface characteristics, and flexural strength of denture base resins. MATERIAL AND METHODS: Heat-polymerized (HP), 3D printed (3D) and computer-aided design and computer-aided manufacture (CAD-CAM)-milled (CC) denture resin specimens (square: 20×20×3.3 mm; beam: 64×10×3.3 mm) were immersed in tap water (TW), RTU EOW (Neutral Anolyte ANK; Envirolyte; EOW), or a commercial denture cleaning tablet solution (Polident 3-Minute; Glaxo SmithKline; PD), mimicking a 5-minute once daily disinfection routine performed up to 3.0 years. Color and surface roughness were recorded (n=3, squares), and changes in color (∆E00) and surface roughness (∆Ra) were calculated. Flexural strength (n=12, beams) and surface hardness (n=18, beams) were measured with a universal testing machine. The fractured surfaces of specimens were examined by scanning electron microscopy and energy dispersive spectroscopy. Data were assessed by performing the Shapiro-Wilk or D'Agostino and Pearson normality tests. Two-way ANOVA or the Kruskal-Wallis test with a post hoc Tukey HSD or Dunn multiple comparisons (α=.05) was used for statistical analyses. RESULTS: No significant changes were found in either color or surface roughness for HP, 3D, and CC resins after 1.5-year and 3.0-year immersion in any of the agents (P>.05). The surface hardness of 3D resins reduced by 14% with TW and by 23% with EOW and PD at 3.0 years. The flexural strengths of all 3 resins were unaffected by 3.0-year immersion (P>.05). CONCLUSIONS: Simulated long-term immersion disinfection with RTU neutral pH EOW did not adversely affect the physical and mechanical properties of HP or CC denture resins.

Effects of two novel denture cleansers on multispecies microbial biofilms, stain removal and the denture surface: an in vitro study.

BACKGROUND: The continuously increasing demand for removable denture appliances and the importance of adequate denture cleaning have led to the development of various denture cleansing products. The aim of this study was to evaluate the efficacy of two novel denture cleansing agents (GE and TM) and three commonly available cleansers (0.5% sodium hypochlorite; NaClO, 0.12% chlorhexidine gluconate; CHX, and Polident®; POL) on multispecies microbial biofilm formation, stain removal and physical properties of dentures. METHODS: The antimicrobial activities of denture cleansing agents were determined against major oral opportunistic pathogens including Streptococcus mutans, Staphylococcus aureus, Escherichia coli and Candida albicans, using time-kill assays. Multispecies microbial biofilms grown on acrylic resins for 72 h were generated to determine the antibiofilm effects of cleansing agents by confocal laser scanning microscopy (CLSM). Evaluations of the tea and coffee stain removal properties and the alterations in the physical properties of dentures were also performed. The toxicity of cleanser residues released from denture acrylics to fibroblast cells was investigated using MTT assay. RESULTS: All denture cleansing agents tested could effectively kill oral bacteria and Candida albicans. Furthermore, after immersion for more than 3 h, the cleansers Polident®, GE and TM could efficiently penetrate and inhibit multispecies denture biofilms with effects similar to 10 min of immersion in 0.5% NaClO. However, immersion in 0.12% CHX for 20 min showed less antibiofilm activity. The NaClO solution had the highest efficacy for removing stains from the artificial teeth. Conversely, the CHX solution enhanced tea and coffee staining, and the teeth immersed in this solution showed clinically unacceptable colour changes (ΔE > 5.5). However, the colour differences of teeth stained and immersed in POL, GE and TM cleansers were in the clinically acceptable range. There was no significant difference among the POL, GE and TM cleansers in terms of stain removal efficacy. The cleansers GE and TM did not alter the surface roughness and colour of the materials, moreover the residues of both cleansers did not exhibit cytotoxicity. CONCLUSION: Two novel denture cleansing agents containing natural products, GE and TM exhibited effective antimicrobial activity, antibiofilm and stain removal capabilities without toxicity or disturbance of the physical properties of acrylics.

Efficacy of removing Candida albicans from orthodontic acrylic bases: an in vitro study.

BACKGROUND: This study evaluated the efficacy of four methods in removing Candida albicans from the acrylic base material used to fabricate removable orthodontic appliances. METHODS: Heat-processed bars of orthodontic acrylic were incubated in a suspension of C. albicans for 2 h at 37 °C. Samples were allocated into five groups (five bars per group) according to the cleaning method: (1) manual brushing using a toothbrush; (2) soaking in a commercial denture cleaning solution; (3) soaking in a commercial mouthwash solution; (4) using an ultrasonic cleaner; and (5) soaking in distilled water as a negative control. Yeast remaining attached to the bars after cleaning were removed by vortexing in growth medium and plated on Sabouraud dextrose agar. The reduction in yeast colony count after cleaning was calculated and expressed as the number of colony forming units per acrylic bar (CFU/bar). The experiment was carried out three times. RESULTS: All four cleaning methods resulted in a significant decrease in viable yeast cells associated with the acrylic bars compared to the control group. The mean percentage reduction in viable yeast cells affected by the cleaning methods was: brushing 89.9%; chlorhexidine 95.8%; ultrasonic cleaning 99.9%; and denture tablet 100%. CONCLUSIONS: All four methods evaluated in this study were effective, to some extent, in removing C. albicans from orthodontic acrylic samples. The most effective, and readily available, cleaning method was the use of commercial denture sterilizing tablets.

Effect of cleansers on denture base resins' structural properties.

INTRODUCTION:: We assessed the effect of different available denture cleansers on the roughness and hardness of polyetherketoneketone, thermoinjection-molded polyamide, and polymethylmethacrylate. MATERIALS AND METHODS:: A total of 150 disc-shaped specimens were fabricated (10 mm × 2 mm) from these three denture base resins, and divided into five subgroups ( n = 10) according to immersion procedures. One of these groups subjected to distilled water served as control, whereas other groups were subjected to daily cleansing with four denture cleansers (Corega, Protefix, Curaprox, and Perlodent) for 8 h a day for 140 days. The surface roughness and hardness values of specimens were recorded by measuring twice at baseline, and again after application of chemical solutions. Topography alterations after treatments were assessed with scanning electron microscopy. The data were subjected to statistical analysis and comparison among groups was done using Kruskal Wallis and Wilcoxon Signed Ranks tests. P-value <0.05 was considered significant. RESULTS:: The surface roughness of polyetherketoneketone, polymethylmethacrylate, and polyamide dentures was increased significantly by chemical solutions of denture cleansers. While the hardness value of polyetherketoneketone was not affected significantly after immersion in denture cleansers, those of polymethylmethacrylate and polyamide decreased significantly. Compared with Curaprox, the effervescent tablets significantly altered the surface hardness and roughness of polyamide. CONCLUSION:: Denture cleansers can considerably alter the surface roughness and hardness of denture base resins and should be used carefully depending on the material.

In Vitro Evaluation of Resilient Liner after Brushing with Conventional and Experimental Ricinus communis-Based Dentifrices.

PURPOSE: To evaluate the effect of experimental (Ricinus communis) and commercial dentifrices used for denture cleaning on abrasiveness (gravimetric method; roughness), hardness, and color stability of a resilient relining material. MATERIALS AND METHODS: Sixty circular (15 × 3 mm) specimens were distributed into four groups: C (control; brushing with water); CO (brushing with Colgate - for natural teeth); CB (brushing with Corega Brite - for complete dentures); RC (brushing with experimental dentifrice). Brushing was performed in a toothbrushing machine with a soft brush and a dentifrice suspension for 50 minutes, calculated to correspond to 1 year of regular brushing. Variables were measured initially and after the trial period. For the gravimetric method, the difference in mass was considered. The surface roughness was measured by a rugosimeter, and the hardness test was performed by a Shore A durometer. Color changes (ΔE; CIE L*a*b* and NBS systems) were measured by a portable spectrophotometer. Results were analyzed by ANOVA/Tukey's test (α = 0.05). RESULTS: The largest mass variation (µg; p < 0.0001) occurred in C (-6.21 ± 3.18). Concerning roughness, CB (0.26 ± 0.04) showed the lowest value, followed by RC (0.29 ± 0.08) and CO (0.34 ± 0.24) (p < 0.0001). Group C produced the greatest surface roughness (0.72 ± 0.25). Hardness values decreased after brushing with water (p = 0.014). No significant differences were found among RC (50.31 ± 1.03), CO (49.11 ± 1.31), CB (49.17 ± 1.23), and C (48.02 ± 1.26). Color stability was similar in all groups (p = 0.135; C: 2.3 ± 0.77; CO: 2.6 ± 0.54; CB: 2.2 ± 0.44; RC: 2.9 ± 1.56). CONCLUSIONS: The use of experimental dentifrice could be indicated, as it showed similar results to the specific dentifrice, keeping the resilient material properties within acceptable values.

Effect of Different Dentifrices on the Surface Roughness of Acrylic Resins: An in vitro Study.

AIM: This study was undertaken to study the effect of three most commonly used dentifrices for denture cleaning and to find out any positive association between number of strokes by toothbrush and surface roughness of acrylic resin. MATERIALS AND METHODS: About 40 acrylic rectangular blocks with high finish were polished until surface roughness was calculated as 0 pirn. The materials tested were distilled water as a control group, Patanjali Dant Kanti, Colgate Total Cream, and Cleansodent as dentifrices. Stroking was done with dentifrices, and surface roughness readings were recorded at 1,000, 9,000, and 18,000 strokes. RESULTS: Patanjali Dant Kanti was found to have maximum abrasive potential followed by Colgate Total Cream, followed by Cleansodent and least by distilled water. CONCLUSION: Surface roughness was found to be directly proportional to the type, size, and fineness of the abrasive component used; the professional denture cleanser (Cleansodent) has less abrasive potential than the regular toothpastes. Among those tested, the highest abrasive potential was found in Patanjali Dant Kanti and lowest by Cleansodent (denture cleanser). CLINICAL SIGNIFICANCE: The patient as well as dentist should choose the dentifrice with utmost care noting the size and type of abrasives used. Washing the dentures normally with water without toothbrush daily and cleaning of dentures once in 10 to 15 days with a soft toothbrush and professional denture cleanser should be the line of maintenance of dentures.

Exposed Dentin: Influence of Cleaning Procedures and Simulated Pulpal Pressure on Bond Strength of a Universal Adhesive System.

PURPOSE: To compare various pre-treatments serving as cleaning procedures of dentin on the bond strength of resin composite promoted by a universal adhesive system applied either in the absence or presence of simulated pulpal pressure. MATERIALS AND METHODS: Prior to application of the adhesive system (Scotchbond Universal) and resin composite (Filtek Z250), ground dentin surfaces were given one of five pre-treatments either without or with simulated pulpal pressure: 1) no pre-treatment, adhesive system in "self-etch" mode, 2) phosphoric acid etching, adhesive system in "total-etch" mode, 3) polishing with pumice on prophylaxis cup, 4) air abrasion with AIR-FLOW PLUS powder, 5) air abrasion with AIR-FLOW PERIO powder; n = 20/group of pre-treatment. After storage (37°C, 100% humidity, 24 h), micro shear bond strength was measured and data analyzed with parametric ANOVA including Bonferroni-Holm correction for multiple testing followed by Student's t tests (significance level: α = 0.05). RESULTS: The ANOVA found type of pre-treatment and simulated pulpal pressure to have no significant effect on dentin bond strength. The explorative post-hoc tests showed a negative effect of simulated pulpal pressure for phosphoric acid etching (adhesive system in "total-etch" mode; p = 0.020), but not for the other four pre-treatments (all p = 1.000). CONCLUSION: Air abrasion with powders containing either erythritol and chlorhexidine (AIR-FLOW PLUS) or glycine (AIR-FLOW PERIO) yielded dentin bond strengths similar to no pre-treatment, phosphoric acid etching, or polishing with pumice. Simulated pulpal pressure reduced the bond strength only when the self-etch adhesive system was used in total-etch mode.

Accelerating effects of cellulase in the removal of denture adhesives from acrylic denture bases.

PURPOSE: Studies of effective methods for the easy removal of denture adhesives from a denture base are not well represented in the literature. We previously assessed the removability of denture adhesives by immersing within denture cleaners, showing that some cleaners have a weak effect, insufficiently effective in daily use. In this study, we prepared a cellulase, as a potential component for denture adhesive removers, and we examined whether the addition of cellulase to denture cleaners is effective in the removal of cream denture adhesives. METHODS: We prepared the cellulase Meicelase as one component for the liquefaction of denture adhesives. We used two denture cleaners and two cream adhesives. After the immersion of plates in sample solutions, we evaluated the area of the sample plate still covered with adhesives. Biofilm removal assay was also performed using denture cleaners containing cellulase. RESULTS: The addition of cellulase accelerated the removal of cream adhesives in immersion experiments to a rate faster than that of water and denture cleaners. However, it did not influence the removability of Candida albicans biofilms from acrylic resin specimens. CONCLUSION: Cellulase hastened the liquefaction of cream adhesives.

Effect of denture-coating composite on Candida albicans biofilm and surface degradation after disinfection protocol.

INTRODUCTION: Denture stomatitis is the most common pathology affecting denture wearers and its main cause is colonisation of dentures with Candida albicans. OBJECTIVE: This study investigated the effectiveness of two commercial composite surface sealants (Biscover(®) LV and Surface Coat(®)) to reduce C. albicans biofilm colonisation on denture resin, as well as their surface integrity after disinfection cycles with 1% sodium hypochlorite solution. METHODS: Heat-cured acrylic resin specimens were manufactured (10 mm × 10 mm × 1 mm). The specimen surfaces were mechanically polished to simulate rough or smooth denture surfaces. Four surface-treatment groups were tested: smooth surfaces [0.3 µm of mean roughness (Ra)]; rough surfaces (3 µm of Ra); rough surfaces treated with Biscover(®) LV; and rough surfaces treated with Surface Coat(®). Specimens of each group were randomly divided to undergo immersion in distilled water or 1% sodium hypochlorite for 30 or 90 cycles each. Specimens of all groups in each immersion solution were tested using a crystal violet (CV) staining assay for biofilm quantification and by scanning electron microscopy for visual analyses of surface integrity and biofilm structure. CV assay data were analysed using one-way analysis of variance (ANOVA) followed by Tukey's multiple comparison test (P < 0.05). RESULTS: The effectiveness and surface integrity of Biscover(®) LV-treated surfaces were similar to those of smooth surfaces, whereas Surface Coat(®) -treated surfaces presented a similar performance to rough surfaces in all solutions and cycles. CONCLUSION: These results suggest the possibility of clinical use of Biscover(®) LV for denture coating on surfaces in which mechanical polish is not indicated, such as the fitting surface.

Evaluating the efficiency of humic acid to remove micro-organisms from denture base material.

OBJECTIVE: To evaluate the efficiency of humic acid substances on removing micro-organisms from denture base materials. BACKGROUND: Old denture wearer needs effective, easy-use and safe denture-cleaning material. MATERIAL AND METHODS: Square-shaped, heat-polymerised acrylic resin specimens (n = 550) were prepared and divided into five groups (n = 110 for each) corresponding to the microbial contamination (Candida albicans, Staphylococcus aureus, Bacillus cereus, Enterococcus faecalis, Pseudomonas aeruginosa). Contaminated specimens were randomly assigned to the application of five different denture-cleaning agents as follows (n = 20 for each): Kloroben, Corsodyl, Steradent, Corega, experimental solution with humic acid. Ten specimens were assessed as an experimental control carried out simultaneously for the treatment groups for each micro-organism. It was divided into two groups: negative control and positive control (n = 5 for each). All acrylic specimens were incubated 37°C for 24 h (for bacterial strains) and 37°C for 48 h (for yeast strains). After incubation period, all brain-heart infusion broths (BHI) which contain disinfectant acrylic specimens were cultured on 5% sheep blood agar (for bacteria) and Sabouraud dextrose agar (SDA) for yeast using loop. The numbers of colony-forming units per millilitre (CFU/ml) were calculated. The results were analysed by Mann-Whitney U-test and Kruskal-Wallis tests (p = 0.05). RESULTS: Corsodyl and Kloroben completely eliminated the adherence of all investigated micro-organisms (100%) and showed the highest removal activity compared with other cleaning agents (p < 0.05). There was no statistically significant difference between Corsodyl and Kloroben (p ≥ 0.05), and there was no statistically significant difference between Corega, Steradent and experimental solution (p ≥ 0.05). CONCLUSION: Humic acid could be used as an alternative 'natural' solution for denture-cleaning agent.

Hardness Changes of Tissue Conditioners in Various Storage Media: An in Vitro Study.

The aim of the present study was to evaluate the effects of storage media on the longitudinal hardness changes of tissue conditioning materials. Four tissue-conditioning materials were used for fabrication of 80 disc-shaped specimens and divided in four groups, stored in four storage media. The specimens underwent artificial ageing corresponding to 30 nights of extra-oral storage. Hardness measurements were obtained at nine intervals between 8 and 240 hours after specimen fabrication. To test the effects of storage media on hardness we employed multivariate modelling (Bonferroni correction; α = 0.05). The materials exhibited varying hardness changes, most pronounced when stored in ambient air.

Effects of short-term immersion and brushing with different denture cleansers on the roughness, hardness, and color of two types of acrylic resin.

PURPOSE: To investigate the cumulative effects of brushing (B) or immersion (I), using different cleansing agents, on the surface roughness, hardness and color stability of a heat-polymerized denture resin, Lucitone 550 (L), and a hard chairside reline resin, Tokuyama Rebase Fast II (T). METHODS: A total of 316 specimens (10 x 2 mm) were fabricated. The specimens (n = 9) were divided into brushing or immersion groups according to the following agents: dentifrice/distilled water (D), 1% sodium hypochlorite (NaOCl), Corega Tabs (Pb), 1% chlorhexidine gluconate (Chx), and 0.2% peracetic acid (Ac). Brushing and immersion were tested independently. Assays were performed after 1, 3, 21, 45 and 90 brushing cycles or immersion of 10 seconds each. Data were evaluated statistically by repeated measures ANOVA. Tukey's honestly significant difference (HSD) post-hoc test was used to determine differences between means (α = 0.05). RESULTS: For L there was no statistically significant difference in roughness, except a significant decrease in roughness by brushing with D. T showed a significant effect on the roughness after 90 immersions with Ac. Hardness values decreased for L when specimens were immersed or brushed in NaOCl and Pb. The hardness of T decreased with increases in the repetitions (immersion or brushing), regardless of the cleaning method. Values of color stability for L resin showed significant color change after brushing with and immersion in Ac and Pb. Brushing with D exhibited a higher incidence of color change. For T there were no significant differences between cleaning agents and repetitions in immersion. A color change was noted after three brushings with the Ac, Chx, and D. Brushing with dentifrice decreased roughness of L. Immersion in or brushing with NaOCl and Pb decreased the hardness of L. For T, hardness decreased with increases in immersions or brushing. Color changes after the immersion in or brushing with cleaning agents were clinically acceptable according to National Bureau of Standards parameters for both resins.

Effect of denture cleansers on color stability and surface roughness of denture base acrylic resin.

BACKGROUND: Color stability of acrylic resin is one of the most important feature for denture wearers. Many patients use detergent solutions to remove denture stains. The purpose of this study was to evaluate color stability and surface roughness of two common acrylic resins in different detergent and tea solutions. MATERIALS AND METHODS: 112 acrylic resin blocks of Meliodent and Acropars (each 56 blocks) were divided into seven groups of different treatment: 1% sodium hypochlorite for 10 min a day for 1 month (H10m), 1% sodium hypochlorite for 8 hours a day for 1 week (H&h), Correga tabs solution for 8 hours a day for 1 month (C&H), tea bag for 2 hours a day for 1 month (T2 h), tea bag for 2 hours a day then 10 min in 1% sodium hypochlorite for 1 month (T-H), tea bag for 2 hours then 8 hours in the Correga tab solution a day for 1 month (T-C), and finally distilled water for 1 month as a control group (con). After specimen's treatment, color (CIE Lab) and surface roughness (Ra, µm) of samples were measured. The results were analyzed by analysis of variance (ANOVA), followed by Tukey's HSD and Dunnett T3. RESULTS: Group T2h exhibited a significant (P<;0.05) color change and control specimens exhibited the lowest color change. Sodium hypochlorite caused a significant (P<0.05) color change in the Acropars group in comparison with the Meliodent group. In the Correga tab solution the difference was not significant (P=0.155). There was a significant (P<0.05) color change in the T-H treatment. The Acropars and Meliodent acrylic resin did not a show significant difference in surface roughness after different treatments. CONCLUSION: Sodium hypochlorite 1% for 10 minutes a day in a month is the recommended hygiene protocol. The color stability of acryl is brand-type dependent but surface roughness is not.

Hardness and surface roughness of enamel and base layers of resin denture teeth after long-term repeated chemical disinfection.

AIM: To evaluate the effect of successive cycles of disinfection in different denture cleansers on the surface roughness and the Vickers hardness of two layers of acrylic resin (base-BL and enamel-EL) of two commercial cross-linked artificial teeth. MATERIALS AND METHODS: The occlusal surfaces of 60 acrylic resin denture posterior teeth (Trilux-TLX and SR Orthosit PE-SRO) embedded in autopolymerizing acrylic resin were ground fat with 1200-grit silicon carbide paper. Specimens were stored in distilled water at 37°C and then submitted to the microhardness (VHN) and roughness (µm) tests. Specimens were stored in distilled water at 37°C for 90 days and submitted to 720 disinfection cycles in sodium hypochlorite at 0.5%, 30% vinegar solution or distilled water (control). Afterward, micro-hardness and roughness tests were again performed. Data were analyzed using two-way ANOVA and Tukey's test (α=0.05). RESULTS: Hypochlorite immersion decreased the hardness of BL and EL of SRO teeth, with an average reduction of 10.11% (p<0.008). TLX teeth demonstrated a hardness reduction of 28.96% of both layers for all solutions including water (p<0.0000). The roughness of both teeth was not affected by denture cleansers (p>0.37). CONCLUSION: Hypochlorite promoted deleterious effects on the hardness of both layers of the artificial teeth tested. Immersion in vinegar and water also resulted in reduction of hardness of TLX teeth. CLINICAL SIGNIFICANCE: The surface hardness of the different layers of cross-linked artificial teeth can be altered by daily disinfection in denture cleansers commonly indicated for removable dentures.

Efficacy of cleaning tablets for removable orthodontic appliances: an in vivo pilot study.

OBJECTIVES: The purpose of this study was to test the cleaning effect of three commercially available effervescent tablet products on acrylic resin surfaces compared to water as control medium. METHODS: A total of 20 volunteers were instructed to wear a vacuum-formed maxillary splint continuously for 96 h. Each splint incorporated four resin discs in the palate area. Each of these PMMA (polymethyl methacrylate) discs was split into two specimens which were analyzed upon removing the splint after the 4-day period. One specimen per disc was analyzed uncleaned and one after cleaning, using one of the investigated tablet products according to the manufacturer's recommendations or water as control medium. The outcomes of cleaning were evaluated with the modified ortho-phthaldialdehyde (OPA) method by determining the amounts of surface protein. RESULTS: Significant differences in relative (%) protein removal were noted between all three tablet products and water, and fittydent super® was significantly more effective in removing biofilm than Kukis®. No significant differences were observed between fittydent super® and NitrAdine® Ortho&Junior™ or NitrAdine® Ortho&Junior™ and Kukis®. CONCLUSION: The modified OPA method proved to be successful in examining protein-containing contaminations on the specimens, and the effervescent products tested were more effective than pure water in removing contaminants from orthodontic appliances. These results are, however, confined to soft plaque not older than 4 days.

Effects of various denture cleansers on surface roughness of hard permanent reline resins.

The aim of this study was to investigate the influence of denture cleansers on surface roughness (Ra, µm) of two hard permanent reline resins and a conventional acrylic denture base resin. Fifty specimens of each material, measuring 10 mm×2 mm were randomly divided into 1 control and 4 experimental subgroups (n=10). Surface roughness values were measured using profilometer before and after immersion in distilled water and in 4 different denture cleansers for 8 h for 140 days. The Kruskal Wallis and Wilcoxon Signed Ranks tests were used for comparison among groups with a significance level of α=0.05. Immersion in denture cleansers significantly increased the surface roughness of reline resins and the difference among the cleansers was statistically significant (p=0.059). Denture cleansers can cause significant surface roughness alterations on hard permanent reline resins and denture base resin where their effect may differ according to the selected resin material.

In vitro evaluation of a novel biofilm remover.

OBJECTIVE: To evaluate a novel device for its efficacy in removing experimental biofilm from root surfaces and its potential for concomitantly removing/roughening the surface substance. METHODS AND MATERIALS: A novel acrylic rotary device (biofilm remover, BR) was tested in vitro in three experiments: surface loss, surface roughness [positive controls: Perioset (PS) and Proxoshape (PR)] and biofilm removal [positive controls: ultrasonic (US) and PS]. Surface loss/surface roughness was evaluated for dentin samples instrumented for three 20 s periods. The calcium removed during instrumentation was analysed after each interval and cumulatively, using atomic absorption spectrophotometry (AAS). Surface roughness was measured using profilometric analysis. Biofilm removal was evaluated on dentin specimens coated with a 64.5 h 6-species in vitro formed biofilm, after one 20 s treatment. Surface loss was analysed using anova with Scheffé post hoc test, and surface roughness/biofilm removal was analysed using Mann-Whitney test (all P ≤ 0.05). RESULTS: Significantly less substance loss [µg (± 1 SD)] was observed with the novel device at all time points, both interval and cumulative (1.0 (± 0.5) versus 9.3 (± 3.2) PS and 9.9 (± 1.9) PR at 60 s). Surface roughness [µm (95% CI)] was significantly lower for BR than for PS and PR [0.00 (-0.01, 0.08) 0.20 (0.16, 0.27) and 0.21 (0.19, 0.24) at 60 s]. Significantly less biofilm bacteria remained after treatment with both BR 4.5 (-0.1, 16.2) and US 1.9 (-0.2, 14.3), compared to PS 52 (27.9, 82.1). CONCLUSIONS: The novel biofilm remover was less damaging to dentin surfaces, while removing biofilm at least as effectively as devices used in this study.

Candida albicans adherence to denture base material: chemical disinfection and the effect of acquired salivary pellicle formation.

PURPOSE: The aim of this study was to evaluate the effect of 1% sodium hypochlorite (H1%) and 4% chlorhexidine gluconate (CG4%) on the adhesion of Candida albicans to denture base acrylic resins, as well as to verify the effect of the acquired salivary pellicle (ASP) formation on this process. MATERIALS AND METHODS: A total of 300 acrylic specimens were immersed in distilled water (control) (n = 100), H1% (n = 100), or CG4% (n = 100) for 30 days. Twenty specimens were used in each experimental period (0, 1, 7, 15, 30 days). At the end of disinfection testing periods, 10 specimens of each group were exposed to human whole saliva to simulate ASP formation, and then all specimens were incubated with C. albicans ATTC 90028. Microorganism adhesion was analyzed by fluorescence microscopy, after staining with Acridine orange. RESULTS: In the 30(th) disinfection cycle in relation to baseline, the H1% or CG4%, without ASP formation, reduced the C. albicans adhesion by approximately 80%; however, with ASP, this reduction after disinfection with H1% was higher (88%). The presence of ASP resulted in higher reduction of adhered fungal cells in comparison to resin without ASP, at the 1(st) H1% or CG4% disinfection cycle, as well as at 30(th) H1% disinfection cycles. CONCLUSIONS: Our results suggest that the presence of saliva might influence the adhesion of C. albicans and improve the effectiveness of methods to reduce fungal adhesion.

Effects of cleansing methods on 3-D surface roughness, gloss and color of a polyamide denture base material.

OBJECTIVE: The purpose of this study was to determine the effects of two denture cleansing methods on 3-D surface roughness, gloss and color of denture base materials. MATERIALS AND METHODS: Thirty disks from nylon (Valplast) and 30 from heat-polymerized acrylic denture base material (Paladon 65) were made and 10 of each material were immersed in water (control), Val-Clean (peroxide cleanser) and Corega Extradent (peroxide cleanser) plus microwaving for a period simulating 30 days of daily cleansing. 3-D surface roughness, gloss and color parameters were measured before and after cleansing using an interferometric profilometer, a gloss meter and a colorimeter. The results were statistically analysed by regression, paired-t, Mann-Whitney and Kruskal-Wallis tests at α = 0.05 level of significance. RESULTS: The results showed significant differences at baseline in L* and b* parameters between materials (p < 0.01), with a significantly lower gloss (p < 0.05) and higher roughness (p < 0.05) for Valplast. After cleansing, Δϵ* was significantly greater in Valplast than Paladon 65 (p < 0.05). Gloss of both materials decreased significantly within the Corega Extradent plus microwave solution (p < 0.05), while roughness increased significantly only for Paladon 65 (p < 0.05). CONCLUSIONS: Valplast was found to have a significantly lower gloss and a higher roughness than Paladon 65 before cleansing. After cleansing, ΔE* increased more in Valplast than in Paladon 65, gloss of both materials decreased and roughness only of Paladon 65 increased within the Corega extradent plus microwaving method.