Surface roughness of denture base and reline materials after disinfection by immersion in chlorhexidine or microwave irradiation

doi: 10.1111/j.1741‐2358.2011.00484.x
Surface roughness of denture base and reline materials after disinfection by immersion in chlorhexidine or microwave irradiation Background: This study evaluated the effect of disinfection by immersion and microwave irradiation on the roughness of one denture base resin (Lucitone‐L) and five relining materials, three hard (Tokuyama Rebase II‐TR, New Truliner‐NT, Ufigel Hard‐UH) and two resilient (Trusoft‐T, Sofreliner‐S). Methods: Fifty specimens were made and divided into groups: CL2 specimens were brushed with 4% chlorhexidine (1 min), immersed in the same solution (10 min) and immersed in water (3 min); MW2 specimens were immersed in water and microwave irradiated (650W; 6 min); CL2 and MW2 specimens were disinfected twice; CL7 and MW7 specimens were submitted to seven cycles using chlorhexidine or microwave irradiation, respectively; W specimens were not disinfected and remained in water (37°C; 7 days). Results: Results were statistically analysed (p = 0.05) and revealed that, at baseline, the highest mean value was observed for T (p < 0.001). Material NT showed increase in roughness after the first (p = 0.003), second (p = 0.001), seventh (p = 0.000) cycles of microwave disinfection and after 7 days of immersion in water (p = 0.033). Conclusions: Resilient liner S presented significant increase in roughness after the second cycle of disinfection with chlorhexidine (p = 0.003). Material T exhibited significantly decreased roughness in group W (p = 0.010), while microwaving produced severe alterations on its surface.     

Denture disinfection by microwave energy: influence of Candida albicans biofilm

doi: 10.1111/j.1741‐2358.2010.00439.x Denture disinfection by microwave energy: influence of Candida albicans biofilm Objective: This study evaluated the influence of the area of Candida albicans biofilm on denture disinfection by microwave energy. Materials and methods: Candida albicans biofilm was allowed to form for 72 h on resin discs, and three small coverage or seven large coverage discs were placed onto the palatal surface of sterile maxillary dentures. Each denture was immersed in 200 ml distilled water and individually irradiated at a power of 450, 630 or 900 W for different time intervals (1, 2 or 3 min) (n = 6). The effectiveness of disinfection was evaluated by counting the residual cells. The data were analysed by anova and Tukey’s HSD test (α = 0.05). Pearson’s correlation test was performed to determine the correlation between effectiveness of sterilisation and temperature. Results: Dentures with a larger area of biofilm demanded a longer irradiation exposure to achieve disinfection (p < 0.001), irrespective of power setting, and in this time no yeast growth was detected. Dentures with small areas of biofilm were disinfected after 1 min at 900 W and 2 min at 450 or 630 W. A positive correlation was found between water temperature and effectiveness of disinfection (r = 0.6170; p < 0.001). Conclusion: The C. albicans biofilm area influenced disinfection by microwave energy; therefore dentures with larger biofilm areas required longer irradiation exposure to be disinfected.     

Examination of denture-cleaning methods based on the quantity of microorganisms adhering to a denture

doi: 10.1111/j.1741‐2358.2011.00461.x Examination of denture‐cleaning methods based on the quantity of microorganisms adhering to a denture Objectives: To investigate effective denture‐cleaning methods, we examined the relationships between the quantity of microorganisms adhering to dentures and the use of a denture brush and the frequency of use of a denture cleanser. Subjects and Methods: Denture plaque was collected from the mucosal surface of the examined dentures, which were 142 and 80 upper and lower complete dentures, respectively, worn by 96 outpatients (mean age: 71.9 years) of a university hospital and 41 nursing home residents (mean age: 84.8 years). The collected microorganisms were counted in terms of isolated representative colonies that were cultured and identified using standard methods. The use of a denture brush, the frequency of use, and the type and soaking time of denture cleansers as denture‐cleaning methods were surveyed. Results: The quantity of microorganisms was significantly lower in dentures of denture brush users than in those of non‐users in the outpatients (p < 0.01, Mann–Whitney U test). The quantity of microorganisms was significantly lower in the dentures of outpatients who used a denture cleanser daily or 3–4 times a week than in those who used one once or less per month and in the dentures of nursing home residents who used one daily than in those who used one at other frequencies (p < 0.05, Kruskal–Wallis test, followed by Dunn’s Multiple Comparison test). Conclusion: Within the limitations of this study, it was concluded that the use of a denture brush and daily use of denture cleanser should be recommended to complete dentures wearers as denture‐cleaning methods that effectively reduce the quantity of microorganisms adhering to dentures.     

Evaluation of the occlusion vertical dimension of complete dentures after microwave disinfection

doi: 10.1111/j.1741‐2358.2011.00567.x Evaluation of the occlusion vertical dimension of complete dentures after microwave disinfection Objectives: An increase in occlusal vertical dimension (OVD) after microwave disinfection may result in the need for adjustments in the complete dentures. This in vitro study evaluated the increase in OVD of maxillary complete dentures submitted to microwave disinfection protocols. Material and methods: Thirty sets of complete dentures were evaluated as follows: Group 1–15 sets had the maxillary complete dentures submitted to microwave disinfection (650 W/3 min), once a week, for 4 weeks. Group 2–15 sets had the maxillary complete dentures submitted to microwave disinfection (650 W/3 min), three times a week, for 4 weeks. The vertical dimension was measured with a micrometre (in mm) before disinfection protocols (baseline readings) and after each week of disinfection. Data were analysed using Wilcoxon and Friedman tests (α = 0.05). Results: For Group 1, no significant difference was found between the increases in OVD and zero, and no significant difference was found between the weeks. For Group 2, the increases in OVD were significantly greater than zero, and the Friedman test showed that weeks 3 and 4 had significantly greater changes than week 1 and that week 4 had significantly greater change than week 2. Conclusion: Microwave disinfection only promoted significant increase in OVD in Group 2, in which the values increased progressively.     

A 2-year study of Candida-associated denture stomatitis treatment in aged care subjects

Objective: To test the efficacy of two methods of treatment for denture stomatitis in aged care institutions. Background data: Candida‐associated denture stomatitis has been associated with a lack of denture hygiene. Materials and methods: Sixty subjects with denture stomatitis were randomly divided into three groups: sodium hypochlorite denture soak, microwaving and control. Both methods of treatment were carried out on a nightly basis for 1 week, excepting the control group. Standardised photographs of the palate and microbial samples of palate, upper and lower dentures were taken before and after treatment. Results: Both hypochlorite and microwave irradiation significantly reduced the numbers of Candida and aerobic bacteria on both dentures and both methods significantly reduced Candida on the palate. However, palatal aerobic bacteria were not significantly reduced by either method and the controls showed insignificant changes at all three sites for both Candida and aerobes. Conclusion: While both methods of denture disinfection were successful, except for the counts of palatal aerobic bacteria, three independent observers of the clinical photographs had difficulty in identifying the controls but were more successful with the treatments. The raters also showed that there was no difference between both methods of disinfection and this agreed with the microbiological analysis.     

Effect of a denture cleanser on the concentration of volatile sulphur compounds and denture biofilm in institutionalised elderly

doi:10.1111/j.1741‐2358.2009.00341.x
Effect of a denture cleanser on the concentration of volatile sulphur compounds and denture biofilm in institutionalised elderly Objective: To determine the effectiveness of a denture cleanser in reducing the concentration of volatile sulphur compounds (VSC) and its antimicrobial action. Background: Micro‐organisms from the denture biofilm can cause local and systemic disease and halitosis. Denture cleansers are important adjuncts in oral care, but there is limited investigation on their effect in malodour compounds. Material and methods: Nineteen institutionalised elderly who wore at least an upper denture were selected; their VSC concentrations were measured and the denture biofilm was collected. In phase 1, the subjects wore their old denture and data were collected before (B₀) and after 7(A₁), 14(A₂), 28(A₃) days of continuous daily use of the denture cleanser. In phase 2, new dentures were inserted and measurements were made at 30(A_1.1), 60(A_2.2), 90(A_3.3) days of treatment. Results: The VSC concentration increased from B₀ to A₁ (p < 0.05)_, but no differences were found for the others intervals of times. Total micro‐organism data did not show a statistical difference between times in Phase I, but in Phase II, there was a statistical difference (p < 0.05) and a progressive re‐colonisation was observed. Conclusion: Within the limits of this study, it was concluded that the denture cleanser had no antimicrobial effect and VSC levels were not reduced.     

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

doi: 10.1111/j.1741‐2358.2011.00520.x 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.     

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

doi: 10.1111/j.1741‐2358.2010.00378.x 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.     

Fracture resistance of maxillary complete dentures subjected to long-term water immersion

doi: 10.1111/j.1741‐2358.2012.00616.x Fracture resistance of maxillary complete dentures subjected to long‐term water immersion Objective: This study investigated the fracture resistance of maxillary acrylic resin complete dentures subjected to long‐term water immersion. Materials and Methods: Maxillary acrylic resin complete dentures were fabricated from five denture base resins. Half of the dentures were stored in water for 50 h, and the other half were kept in water for 180 days before testing. Ten specimens were fabricated per group. The flexural load at the proportional limit (FL‐PL) of the dentures was tested. Results: A two‐way anova revealed a significant difference in FL‐PL because of the denture base material variable. There were no significant differences in FL‐PL because of the effect of water immersion and the interaction between the effect of water immersion and the denture base material. The FL‐PLs of the dentures fabricated with the two conventional heat‐processed resins, the pour‐type autopolymerizing resin and the microwave energy‐processed resin were not significantly different from each other; they were significantly higher than the light‐activated resin in regard to their FL‐PL. Conclusion: The FL‐PLs of the maxillary acrylic resin complete dentures did not change after long‐tern water immersion, and the FL‐PL of the denture fabricated from the light‐activated resin was lower than those of the other materials.     

Clinical and microbiological efficacy of three different treatment methods in the management of denture stomatitis

Gerodontology 2010; doi: 10.1111/j.1741‐2358.2009.00354.x
Clinical and microbiological efficacy of three different treatment methods in the management of denture stomatitis Objective: This study evaluated. the effect of mouthrinses and tissue conditioner on the clinical findings and microbial flora of 60 patients with Newton’s type II denture stomatitis (N2DS) Background: Denture stomatitis is a common problem in complete denture wearers. Materials and methods: Sixty patients with N2DS were included in this study and divided into three groups. Two groups of patients were instructed to rinse their mouth with the designated mouthrinses DioxiDent and Corsodyl twice daily for 1 min and to soak their dentures overnight in these solutions for 15 days. For the third group, tissue conditioner was placed in each of 20 patients’ existing maxillary dentures. Patients were evaluated both clinically and microbiologically at baseline and after 15 days. Palatal swabs and smears were taken from each patient before and after treatment and these samples were examined mycologically. The difference between Candida colonisation before and after treatment and the differences between pre‐treatment and post‐treatment clinical findings were assessed. Results: DioxiDent and Corsodyl showed an improvement in palatal inflammation and a decrease in Candida colonisation compared to Visco‐gel. Conclusions: The effectiveness of topical chlorine dioxide and chlorhexidine gluconate in the management of N2DS was demonstrated.     

The occurrence of porosity in reline acrylic resins. Effect of microwave disinfection

Background: Microwave energy has proved to be an effective method for disinfecting acrylic dentures. However, the effect of microwave heating on the porosity of autopolymerising denture reline resins has not been investigated. Objective: The purpose of the study was to determine the effect of microwave disinfection on the porosity of autopolymerised denture reline materials (Kooliner‐K, New Truliner‐NT, Tokuso Rebase Fast‐TR and Ufi Gel Hard‐UGH) and a conventional heat‐polymerised denture base resin (Lucitone 550‐L). Material and methods: Specimens (10 mm × 20 mm × 1 mm) were obtained from the impression surface of the palatal mucosa in a single person and divided into four groups (n = 5). The porosity was evaluated after polymerisation (C1), after two cycles of microwave disinfection (MW2), after seven cycles of microwave disinfection (MW7) and after 7 days storage in water at 37°C (C2). Specimens from group MW7 were exposed to microwave disinfection daily being stored in water at 37°C between exposures. All the replicas were sputter coated with gold and micrographs/digital images were taken of each replica using scanning electron microscopy at magnification × 100. The SEM micrographs were then examined using an image analyser to determine the number of pores. Comparison between materials and groups were made using Kruskal–Wallis tests. Results: MW7 resulted in a significant increase in the number from the pores of material K, but decreased in number in reline material TR and UGH reline resin. The number of pores in materials NT and L remained unaffected following microwave disinfection. Conclusion: Differences in the porosity amongst the materials and for different experimental conditions were observed following microwave disinfection.     

Effect of microwave treatment on the shear bond strength of different types of commercial teeth to acrylic resin

doi:10.1111/j.1741‐2358.2009.00333.x
Effect of microwave treatment on the shear bond strength of different types of commercial teeth to acrylic resin Objective: The purpose of this study was to verify the effect of microwave treatment on the shear bond strength of commercial types of teeth to acrylic resin, when the glossy ridge laps were unmodified (groups 1 and 5), bur abraded (groups 2 and 6), bur grooved (groups 3 and 7) or etched by monomer (groups 4 and 8). Background: Controversial findings have shown that mechanical or chemical changes in ridge‐lap surface of the tooth increase or decrease the bond strength between tooth and acrylic resin, and the microwave disinfection may cause different changes on this bond strength. Materials and methods: Eighty specimens (n = 10) were made with the acrylic resin bonded to tooth glossy ridge lap, polymerised in water at 74°C for 9 h, and deflasked after flask cooling. Specimens of the groups 5, 6, 7 and 8 were individually immersed in 150 ml of water and submitted to microwave treatment in an oven at 650 W for 3 min. Control specimens (groups 1, 2, 3 and 4) were not microwave treated. Shear bond strength test was performed in an Instron machine with a cross‐speed of 1 mm/min. Collected data were submitted to anova and Tukey’s test (α = 0.05). Results: Microwave treatment decreased the shear bond strength values of the tooth/resin bond. In the microwaved and non‐microwaved procedures, mechanical retention improved the shear bond strength when compared with the control and monomer treatments. Conclusion: Shear bond strength of the tooth/resin bond was influenced by the microwave treatment and different commercial teeth association, and was lower for the Biotone tooth.     

Complete denture hygiene and nocturnal wearing habits among patients attending the Prosthodontic Department in a Dental University in Brazil

Gerodontology 2010; doi: 10.1111/j.1741‐2358.2010.00369.x Complete denture hygiene and nocturnal wearing habits among patients attending the Prosthodontic Department in a Dental University in Brazil Objective: The aim of this study was to evaluate the overnight wearing and cleaning habits of complete denture wearers. Background: Successful complete denture treatment can be achieved when the patients are motivated and aware of appropriate denture wear and hygiene. Materials and methods: A sample of 224 complete denture wearers (162 women) aged 37–89 years was studied. Inclusion criteria comprised edentulous subjects who had received their new complete dentures between 2000 and 2005 in the Dental Clinic of the Araçatuba and Araraquara Dental School, São Paulo State University. Ethical approval was sought and granted. Subjects were interviewed using questions related to overnight denture wearing and denture cleaning habits. Possible statistical relationships among some of items were analysed by the chi‐square test at 5% significance level. Results: Of the patients, 55.8% removed their dentures during the overnight period and 88% did this every day. Among them, 66.4% removed both dentures. Most of the patients used brushing with toothpaste (105 patients – 46.87%) as a cleaning method. More than a half of the subjects (63.4%) showed biofilm and calculus on their dentures. Conclusion: The patients need instructions and motivation concerning denture hygienic and denture removal overnight.     

Relining of prosthesis with auto‐polymerizing hard denture reline resins: effect of post‐polymerization treatment on flexural strength

Background: It has been suggested that microwave irradiation and prosthesis immersion in hot water after its polymerization may improve mechanical and viscoelastic properties of acrylic resins. Purpose: This study was proposed to verify the influence of microwave post‐polymerization (PP) treatment over the flexural strength of thermo‐polymerizing acrylic resin specimens (QC‐20) relined or not with two different composition hard chairside auto‐polymerizing reliners [Kooliner (K) and New Truliner (NT)]. Materials and Methods: For this study, 50 specimens of 64 × 10 × 3.3 mm were polymerized and distributed into five groups. G1 (control) specimens without relining and PP; G2 specimens relined with K, without PP; G3 specimens relined with NT, without PP; G4 specimens relined with K, with PP (microwave irradiation with 650 W for 5 min); G5 specimens relined with NT, with PP. Tests were performed on a universal testing machine Instron 4411 with compression speed of 5 mm/min. Results: Specimens of K without PP did not show statistically different results (p < 0.05) when compared with control. However, when submitted to PP these specimens showed a significant increase in flexural strength. Specimens of NT showed the lowest flexural strength of all groups, with or without PP when compared with control and K groups. Conclusion: Microwave PP (650 W for 5 min) proved to be an effective method of improving the flexural strength of K relined prosthesis. However, it did not seem to affect NT specimens.     

Effect of denture adhesive on the micro-organisms in vivo

doi: 10.1111/j.1741‐2358.2010.00381.x Effect of denture adhesive on the micro‐organisms in vivo Background: Denture adhesives increase the retention and stability of dentures in edentulous patients, especially in cases where salivary flow is impaired or in the management of traumatised oral mucosa. Objectives: The effect of a denture adhesive on the oral flora at different time intervals. Method: Thirty denture‐wearing patients were involved in this study. While half of the group received a denture adhesive, the other half did not. At baseline, 1 and 2 months after delivering the dentures, smear samples were obtained from the saliva, palate and the dentures. Candida albicans, Candida krusei, Candida glabrata, Candida spp., Staphylococcus aureus, Moraxella catarrhalis, α‐haemolytic streptococci, β‐haemolytic streptococci, Pneumococcus aureus, S. anginosus, S. intermedius, S. constellatus, S. sanguis, S. gordonii, S. mitis, S. mutans, S. salivarius, and yeasts were investigated. The data were statistically analysed using anova and repeated measures. Results: Most types of the micro‐organisms were not seen and could not be analysed statistically except α‐haemolytic streptococci and C. albicans. No statistically significant difference was found for α‐haemolytic streptococci and C. albicans in saliva, palate and the denture at all time intervals. Conclusions: Prolonged use of the denture adhesive tested up to 2 months did not yield to increase in micro‐organisms of the oral flora.     

Effects of denture maintenance on satisfaction levels of Taiwanese elderly using removable partial dentures: a pilot study

doi: 10.1111/j.1741‐2358.2011.00500.x
Effects of denture maintenance on satisfaction levels of Taiwanese elderly using removable partial dentures: a pilot study Objective: The aim of this study was to evaluate the correlation between patient satisfaction with removable partial dentures and denture maintenance by patients, including regular application of denture adhesives and cleansers. Background: The success of removable partial dentures depends on patient satisfaction with dentures and their regular denture maintenance. Materials and methods: Demographic information, the Oral Impacts on Daily Performance (OIDP) indicator and details of denture maintenance (including the use of denture cleansers and adhesives) were collected from 193 (41.5% men and 58.5% women) participants by using questionnaires. A dentist performed oral examinations to evaluate denture function according to the OIDP items photographically and recorded the number of remaining teeth and Kennedy’s classification. Results: Most participants were satisfied with their removable partial dentures and tended to have higher satisfaction levels than the dentist’s estimation. Further, those using denture adhesives and cleansers had higher satisfaction levels than those not using such denture maintenance. Conclusions: Appropriate education regarding denture use is important because regular denture maintenance by patients affects their degree of satisfaction with dentures, as well as the dentist’s skill and the patient’s oral condition. Dentists could use this information to predict the potential success of dentures.     

Impact of new prostheses on the oral health related quality of life of edentulous patients

Objective: A study was conducted to evaluate the impact of the placement of complete dentures by using the Global Oral Health Assessment Index (GOHAI). Background: Oral health quality of life indicators can be used to evaluate the effects of dental treatments. Material and methods: The 26 participants were treated in a French University Clinic during 2002. They were randomly divided into two groups. Each group received new prostheses, but evaluation of the quality of life was made at different periods [baseline, denture placement (group 1), 6 and 12 weeks (group 2) after placement]. A questionnaire was used to collect information on patient's satisfaction with the previous and new prostheses. Nonparametric tests were used to test the relationships between patients’ satisfaction or baseline data and GOHAI variations with time as well as to compare mean values of GOHAI within each group. Results: At baseline, the impact of oral health problems was apparent; the mean GOHAI‐Add score was 45.8 (10.2). Six weeks after placement of the new denture, there was no difference in GOHAI scores compared with the initial assessment. An improvement in GOHAI score was observed 12 weeks after the participants received their new dentures (p < 0.05). Change in GOHAI‐Add scores was negatively correlated with the initial GOHAI‐Add score. Patients who preferred the new prosthesis enjoyed a positive change in GOHAI scores (p < 0.001). There was a relationship between participants’ satisfaction with the new dentures and change in GOHAI scores (p < 0.05). Conclusion: The GOHAI can be used to evaluate needs for and effect of the making of new complete dentures.     

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 (α = 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.     

Complete denture wearing and fractures among edentulous patients treated in university clinics

doi: 10.1111/j.1741‐2358.2011.00551.x
Complete denture wearing and fractures among edentulous patients treated in university clinics Objective: The prevalence of wearing and fracture of complete dentures was evaluated among edentulous patients treated in two dental schools in Brazil. Background: Acceptance and wearing of complete dentures are related to adaptive behaviour of edentulous patients. However, one reason that could interfere with the wearing dentures is their potential to fracture, which is still a common complication in denture rehabilitation practice. Material and methods: Two hundred and twenty‐four edentulous patients rehabilitated with complete dentures from 2000 to 2005 in Araçatuba and Araraquara Dental School, University of State of São Paulo, were assessed in 2006 and 2007 to answer a questionnaire about wearing and fracture of their dentures. Statistical analysis were performed using Epi Info software and chi‐squared test to compare maxillary and mandibular data (α = 0.05). Results: Almost 26% of the patients did not wear their dentures, and among the remainder, the majority wore the maxillary denture. About 30% of the dentures were fractured, with higher prevalence in the maxillary arch (p = 0.003). Conclusions: Discontinuation of wearing dentures was quite high, especially considering the treatment which was carried out in university clinics. Prevalence of fractures was also high, greater for the maxillary denture, and was one of the main reasons for non‐wearing of complete dentures.     

Bond strength of denture teeth to acrylic resin: effect of thermocycling and polymerisation methods

Background: Failure of bonding between acrylic resin teeth and denture base material is a considerable problem for patients who wear complete dentures. Objective: The purpose of this study was to evaluate the bond strength between acrylic resins and resin denture teeth with different thermocycling and polymerisation methods. Materials and methods: Microwave‐polymerised (Onda‐Cryl), heat‐polymerised (Clássico) and autopolymerising (Jet) acrylic resins and resin denture tooth (Biotone) were used. The acrylic resins were polymerised according to the following: (A) microwave – fast cycle, Onda‐Cryl; (B) microwave – long cycle, Onda‐Cryl; (C) microwave – manufacturer’s cycle, Onda‐Cryl; (T) water bath – long cycle, Clássico; and (Q) bench polymerisation cycle, Jet. Twenty specimens were prepared for each polymerisation method. Ten were thermocycled, and 10 did not receive thermocycling. For the purpose of the study, a shear test was used. Data were analysed with the Kruskal–Wallis test and Dunn’s multiple comparisons test (p = 0.05). Results: Cycles B, C and T were similar (p > 0.05), and had statistically higher bonding values than cycles A and Q (p < 0.05) for the thermocycled and non‐thermocycled groups. For all cycles, there were no statistically significant differences between thermocycled and non‐thermocycled groups (p > 0.05), except for cycle Q (p = 0.0038). Conclusion: Thermocycling decreased the bond strength, but not significantly for microwave and heat‐polymerised cycles. Regarding the bond strength of denture teeth to acrylic resin, the fast microwave polymerisation cycle should be avoided when polymerising Onda‐Cryl acrylic resin. In addition, Jet acrylic resin is not adequate for use in denture repair.