Masticatory performance, self-perception of oral health, oral health-related quality of life and nutritional status of completely edentulous elderly patients submitted to different rehabilitation treatments: A cross-sectional study.

BACKGROUND: The impact of treatments on completely edentulous individuals on masticatory performance (MP), oral health-related quality of life (OHRQoL), nutritional status (NS) and socio-economic profile (SP) is unclear in the literature. OBJECTIVE: To compare the MP, OHRQoL, NS and SP of totally edentulous elderly users of bimaxillary complete dentures (CD) and users of lower implant-supported fixed complete dentures (IFCD). METHODS: Forty participants were allocated into groups according to rehabilitation treatment (n = 20): bimaxillary CD (G1) and lower IFCD, and upper CD (G2). The evaluation of MP used almonds by the method of sieves. Four questionnaires (Geriatric Oral Health Assessment Index-GOHAI and Oral Health Impact Profile Edent-OHIP-Edent, Brazilian Economic Classification Criteria-ABEP and Mini Nutritional Assessment-MNA) were applied to assess the OHRQoL, SP and NS of the elderly, respectively. After evaluating the statistical assumptions, the Mann-Whitney (α = .05) test was applied to compare the groups regarding MP, OHRQoL, NS and SP. Spearman's correlation (α = .05) was performed to verify the correlation between the MP, the OHRQoL and the NS of the participants. RESULTS: G2 showed better MP (p < .05) in all masticatory cycles, OHRQoL (p < .05) and NS than the G1. However, the participants' self-perception of oral health did not differ between groups (p < .05). A moderate negative correlation was found between MP and OHRQoL for 40 masticatory cycles (r2 = -0.513; p = .001). CONCLUSION: Individuals rehabilitated with IFCD had a higher average monthly family income and achieved superior behaviour in MP and OHRQoL, in addition to lower risks of malnutrition when compared to individuals using bimaxillary CD.

A Randomized Clinical Trial of Oral Health-Related Quality of Life, Peri-Implant and Kinesiograph Parameters in Wearers of One-or Two-Implant Mandibular Overdentures.

PURPOSE: The present randomized clinical trial compared the oral health-related quality of life (OHRQoL), peri-implant parameters, mandible movements, and maxillary complete denture movement during chewing between wearers of single- (1-IOD) and wearers of two-implant overdentures (2-IODs) for a period of 12 months. MATERIALS AND METHODS: Twenty-one complete denture wearers were randomly allocated into two parallel groups: 1-IOD (n = 11) or 2-IODs (n = 10). The validated Brazilian version of the OHIP-EDENT was used to evaluate the OHRQoL. A kinesiograph recorded maxillary complete denture movement during chewing of hard food testing (polysulphide impression material) and soft food testing (bread). Peri-implant parameters were also recorded: plaque index (PI), bleeding on probing (BOP), and probing depth (PD). The Friedman test was used to compare the OHRQoL data and peri-implant parameters among periods; the Mann-Whitney test was performed to compare the groups (1- and 2-IODs). One-way ANOVA and the Bonferroni test were used to compare mandible movement during chewing among periods, and the t-test for independent samples was used to compare the groups. Maxillary complete denture movement was analyzed using three-way ANOVA followed by the Bonferroni test. All statistical analyses were performed at α = 0.05. RESULTS: Both treatments led to better general OHRQoL in comparison to conventional complete dentures (p < 0.001). Better OHRQoL was observed among 2-IOD patients at the 12-month follow up (p = 0.034). Peri-implant parameters were similar irrespective of the group and follow-up period. Vertical opening was significantly higher among 1-IOD patients at 3 months (p = 0.038). Decreased maxillary denture vertical intrusions were observed with complete dentures in comparison with overdentures (p = 0.006), regardless of the food test (p = 0.251); however, vertical intrusion was significantly higher among 1-IOD patients (p = 0.043). CONCLUSIONS: This study suggested that 1-IOD can improve patient OHRQoL and may be similar to 2-IODs in preservation of both peri-implant parameters and masticatory movements.

Proinflammatory cytokine production from NOK-SI keratinocytes after exposure to denture adhesives.

STATEMENT OF PROBLEM: Although the cytotoxicity of denture adhesives has been widely assessed, data on the release of proinflammatory cytokines from oral epithelial cells are still scarce. PURPOSE: The purpose of this in vitro study was to evaluate the proinflammatory cytokines interleukin (IL) 1ß, IL-6, and tumor necrosis factor α (TNF-α) released from human oral keratinocytes after exposure to denture adhesives. MATERIAL AND METHODS: Eluates of the Ultra Corega cream, Corega powder Fixador Ultra, and Corega strip denture adhesives were created at 1% wt/vol after 24 hours of exposure in a Dulbecco modified Eagle medium culture. The release of IL-1ß, IL-6, and TNF-α was measured using a sandwich enzyme-linked immunosorbent assay after the oral epithelial cells (NOK-SI) had been exposed to the eluates for 3, 6, and 24 hours (n=6). RESULTS: IL-1ß release from the strip was higher at 3 hours compared with the control (Bonferroni post hoc test, P=.016). IL-6 releases from the cream and powder denture adhesives at 6 and 24 hours were higher than for the controls (Bonferroni post hoc test, P<.05). TNF-α release was not detectable in some groups and periods. CONCLUSIONS: In long periods, denture adhesive strips do not induce any change on cytokine release from human oral keratinocytes.

Mandibular kinesiographic pattern of women with chronic TMD after management with educational and self-care therapies: A double-blind, randomized clinical trial.

STATEMENT OF PROBLEM: Limited mandibular movements are one of the most important signs of temporomandibular disorders (TMDs) and may cause functional difficulties. PURPOSE: The purpose of this double-blind, randomized clinical trial was to evaluate the effect of treatment with only educational or education associated with self-care therapies on the pattern of mandibular movements of women with chronic painful TMDs. MATERIAL AND METHODS: Forty-two women were selected and randomly divided into 3 groups, control group (CG, n=13), education group (EG, n=16), and education and self-care group (ESG, n=13), according to the sequence of treatment they received. A kinesiograph device recorded mandibular movements during maximum mouth opening and mastication at baseline (T0) and at 30-day (T1) and 60-day (T2) follow-up. Kinesiographic data were statistically analyzed using 1-way ANOVA, followed by the Bonferroni test for multiple comparisons of means (α=.05). RESULTS: The ESG group demonstrated an improvement in the maximum vertical opening (MVO= 5.1 ±3.4 mm; P=.012) and anteroposterior mandibular movement (MAM) during maximum opening (7.4 ±9.5; P=.019), significantly higher than that of the EG (MVO=1.8 ±3.5 mm; MAM=0.8 ±5.0 mm) and the CG (MVO=0.9 ±3.8 mm; MAM=0.8 ±4.4 mm) after 30 days of follow-up. Moreover, at T1, vertical mandibular movement during mastication was significantly higher in the ESG group (17.4 ±1.7 mm) than in the EG group (15.0 ±2.8, P=.027). No significant differences were found between the women who received treatment with educational and self-care therapies for 60 days and the women who received this treatment for 30 days. CONCLUSIONS: In the short-term, education and self-care treatment positively influenced the mandibular movement pattern of women with chronic painful TMDs.

Crossover clinical trial of different methods of removing a denture adhesive and the influence on the oral microbiota.

STATEMENT OF PROBLEM: The difficulty of removing denture adhesive is a common problem reported by users of these products. PURPOSE: The purpose of this clinical study was to investigate the effectiveness of different cleaning protocols for removing a denture adhesive (DA) and the influence on the oral microbiota. MATERIAL AND METHODS: Twenty participants wearing well-fitting complete dentures were instructed to use a denture adhesive 3 times a day during a 4-week trial, divided into 4 stages: (A) control-3 daily denture brushings using water at ambient temperature, (B)-3 daily denture brushings using water at ambient temperature plus coconut soap, (C)-3 daily denture brushings using water at ambient temperature plus dentifrice; (D)-3 daily denture brushings using water at ambient temperature combined with immersion in sodium perborate solution for 5 minutes before nocturnal sleep. After each 1-week stage, saliva specimens were collected. A dye was used to display and quantify the remaining DA on the internal surface of the maxillary dentures as a percentage. For microbiological analysis, the saliva was diluted and plated onto Petri dishes containing a nonselective culture medium and Candida spp culture media. After the incubation period, Candida species were identified and the number of colony forming units (CFU/mL) was calculated. RESULTS: A significant difference was found among the 4 cleaning methods for the quantification of remaining DA (Friedman, P=.036). Brushing the dentures with coconut soap, dentifrice, or water combined with immersion in sodium perborate solution was more effective in removing DA than brushing with only water. The cleaning methods did not influence the quantification of microorganisms in general or Candida albicans and other Candida species in particular. CONCLUSIONS: Brushing the dentures with coconut soap, dentifrice, or water combined with immersion in sodium perborate solution was more effective for removing cream-type denture adhesive than brushing with only water.

Bond Strength of Artificial Teeth Attached to a Microwave-Polymerized Denture Base Resin after Immersion in Disinfectant Solutions.

PURPOSE: To evaluate the bond strength between two types of acrylic resin teeth and a microwave denture base resin after immersion in disinfectant solutions for 180 days. MATERIALS AND METHODS: Eighty specimens made of acrylic resin teeth (Biotone and Biotone IPN) attached to a microwave polymerized denture base resin (Nature-Cryl MC) were divided into eight groups (n = 10) according to the treatment (distilled water-control, 2% chlorhexidine digluconate, 1% sodium hypochlorite and sodium perborate solution-Corega Tabs). The shear strength tests (MPa) were carried out using a universal testing machine with a 0.5 mm/min speed. Data analysis was performed using ANOVA and multiple comparison Student-Newman-Keuls post hoc test (α = 0.05). RESULTS: Biotone IPN showed similar results among the groups (distilled water, 8.25 ± 1.81 MPa; chlorhexidine, 7.81 ± 3.34 MPa; hypochlorite, 7.75 ± 3.72 MPa; and Corega Tabs, 7.58 ± 2.27 MPa, whereas Biotone showed significantly lower shear bond strength values for the groups immersed in Corega Tabs (5.25 ± 3.27 MPa) and chlorhexidine (6.08 ± 2.35 MPa). CONCLUSIONS: Soaking the dentures in 1% sodium hypochlorite could be recommended as a disinfectant solution for dentures fabricated with conventional acrylic resin denture teeth and microwave denture base resin. For dentures fabricated with IPN teeth and microwave denture base resin, all the soaking solutions evaluated in this study could be suggested to denture wearers.

In Vitro Assessment of the Abrasion Resistance of Two Types of Artificial Teeth Submitted to Brushing.

PURPOSE: To assess the effect of brushing with different solutions on the abrasion resistance of two types of acrylic resin teeth. MATERIALS AND METHODS: Maxillary premolars from two types of acrylic teeth (Biotone and Biotone IPN) were divided into six groups (n = 12), according to the solution used during brushing: distilled water (control), coconut soap, or dentifrice. A mechanical brushing machine was used to simulate approximately 1 year of brushing (11,000 strokes). The weight loss (WL) of teeth was obtained from the difference between the initial (IW) and final weight (FW) of each specimen, and the mean of percentage of weight loss (PWL) was calculated for each group. Data were analyzed using the Kruskal-Wallis test, followed by Bonferroni's post-test comparison (α = 0.05). RESULTS: A statistically significant difference was found for the factor solution (p < 0.001). Brushing using dentifrice caused the highest values of weight loss (-0.50%), in comparison with the groups brushed with coconut soap (0.00%) or distilled water (0.00%). CONCLUSIONS: For both types of artificial teeth, brushing with dentifrice produced higher abrasion than brushing with coconut soap or water.

Antimicrobial activity of a tissue conditioner combined with a biocide polymer.

BACKGROUND: The characteristics of tissue conditioners support microorganism development that can threaten the health of the dentures user. PURPOSE: The object of this study was to evaluate the effect on antimicrobial activity, roughness and wettability surface of a tissue conditioners material combined with the antimicrobial polymer poly (2-tert-butilaminoethyl) methacrylate (PTBAEMA). MATERIALS AND METHODS: Specimens of tissue conditioner (Coe Soft(®)) were divided into three groups, according to the concentration of PTBAEMA incorporated (0, 10 and 25%). Antimicrobial activity was assessed by adherence assay of one of the microorganisms, Staphylococcus aureus, Streptococcus mutans and Candida albicans. Roughness measurements were made using a Mitutoyo SJ-400, and the mean arithmetic roughness values (Ra) obtained were used for the comparisons. The wettability properties were determined by contact angle measurements. RESULTS: The group containing 25% of PTBAEMA inhibited totally the S. aureus and S. mutans biofilm formation. A significant reduc tion in the S. aureus (Kruskal-Wallis, p = 0,001) and S. mutans (Kruscal-Wallis, p = 0,001) count for 10% PTBAEMA group compared with respective control group. No significant difference was found for C. albicans among PTBAEMA groups and control group (ANOVA, p > 0,05). Incorporating 10 and 25% PTBAEMA increased surface roughness and decreased contact angles (ANOVA and Tukey's post hoc tests, α = 5%). CONCLUSION: Incorporating 10% PTBAEMA into tissue conditioner increases wettability and roughness of tissue conditioner surface; and decreases the adhesion of S. mutans and S. aureus on material surface, but did not exhibit antimicrobial effect against C. albicans. SIGNIFICANCE: The PTBAEMA incorporated into tissue conditioner could prevent biofilm formation on elderly patient.

Masticatory performance of complete denture wearers after using two adhesives: a crossover randomized clinical trial.

STATEMENT OF PROBLEM: Masticatory performance analysis of conventional complete denture wearers who use denture adhesives is scarce in the dental literature. PURPOSE: The purpose of this study was to assess the effect of the use of 2 denture adhesives on the masticatory performance of conventional complete denture wearers by means of a crossover study. MATERIAL AND METHODS: Forty individuals who were edentulous received new maxillary and mandibular complete dentures, and, after an adaptation period, were submitted to masticatory performance analysis without denture adhesive (control). The participants were randomly divided and assigned to 2 protocols: protocol 1, denture adhesive 1 (Ultra Corega cream tasteless) use during the first 15 days, followed by no use of denture adhesive over the next 15 days (washout), and then use of denture adhesive 2 (Ultra Corega powder tasteless) for 15 days; protocol 2, denture adhesive 2 (Ultra Corega powder tasteless) use during the first 15 days, followed by no use of denture adhesive during the next 15 days (washout), and then use of denture adhesive 1 (Ultra Corega cream tasteless) for 15 days. The masticatory performance was assessed immediately after the use of denture adhesive by means of the sieve method, in which participants were instructed to deliberately chew 5 almonds for 20 chewing strokes. Masticatory performance was calculated by the weight of comminuted material that passed through the sieves. Data were analyzed by a 1-way ANOVA for paired samples and the multiple comparison of means by using the Bonferroni test (α=.05). RESULTS: A significant increase in masticatory performance was noted after using the Ultra Corega cream (mean, 32.6%) and Ultra Corega powder (mean, 31.2%) when compared with the control group (mean, 19.8%) (P<.001). No significant difference was found between the 2 denture adhesives evaluated. CONCLUSION: The use of denture adhesive improved the masticatory performance of conventional complete denture wearers. No difference was found in masticatory performance with the use of cream or powder denture adhesive.

Chemical characterization and flexural strength of a denture base acrylic resin with monomer 2-tert-butylaminoethyl methacrylate.

PURPOSE: The objectives of this study were to investigate the flexural strength (FS) and chemical interaction between 2-tert-butylaminoethyl methacrylate (TBAEMA) and a denture base acrylic resin. MATERIALS AND METHODS: Specimens were divided into five groups according to the concentration of TBAEMA incorporated in acrylic resin Onda-Cryl (0%, 1%, 2%, 3%, 4%) and were submitted to Fourier transform infrared spectroscopy (FTIR), electron spectroscopy for chemical analysis (XPS-ESCA), and differential scanning calorimetry (DSC) analyses. FS of the specimens was tested, and results were analyzed by ANOVA/Tukey's test (α < 0.05). RESULTS: Different nitrogen ratios were observed on specimens' surfaces: 0.36%, 0.54%, 0.35%, and 0.20% for groups 1%, 2%, 3%, and 4%, respectively. FTIR indicated copolymerization of acrylic resin and TBAEMA, and DSC results demonstrated a decrease in glass transition temperature (Tg ). Significant differences were found for FS (p < 0.05). The mean values were 91.1 ± 5.5,(A) 77.0 ± 13.1,(B) 67.2 ± 12.5,(B) 64.4 ± 13.0,(B) and 67.2 ± 5.9(B) MPa for groups 0%, 1%, 2%, 3% and 4%, respectively (same superscript letters indicate no significant difference). CONCLUSIONS: The incorporation of TBAEMA in acrylic resin resulted in copolymerization and the presence of amine groups on specimens' surfaces, and in decreases of Tg and FS.

Effectiveness of disinfectant solutions associated or not with brushing on the biofilm control of a 3D printed-denture base resin.

BACKGROUND: The formation of biofilm on denture bases is a recurrent clinical problem that favors the development of denture stomatitis. The effectiveness of a hygiene protocol in a 3D-printed denture base resin is still uncertain. OBJECTIVE: To evaluate of the effectiveness of immersion, associated or not with brushing in a soap solution, on the biofilm control of a 3D-printed denture base resin. METHODOLOGY: Specimens of denture base resins [Cosmos Denture (COS) and Classico (CLA/control)] were contaminated in vitro with Candida albicans and immersed in sodium hypochlorite 0.25% (SH, alkaline peroxide) AP, chlorhexidine digluconate 2% (CD or PBS-Control), associated or not with brushing with 0.78% Lifebuoy soap. Roughness was evaluated before and after brushing and immersion. The effectiveness of the protocols was assessed by CFU/mL, cellular metabolism (XTT), scanning electron microscopy (SEM), and confocal scanning laser microscopy. Data were analyzed by T student, ANOVA/Welch, and Tukey/Gomes-Howell pos-hoc tests (α = 0.05). RESULTS: CLA showed greater roughness than COS. CFU/mL and XTT were higher in COS resin with a higher hyphae formation. Immersion in SH and CD eliminated CFU/mL and reduced XTT for both resins, associated or not with brushing. AP reduced CFU/mL only when associated with brushing. CONCLUSIONS: The biofilm on the 3D-printed resin was thicker and presumably more pathogenic, regardless of its smoother surface. Immersions in SH 0.25% and CD 2% are effective hygiene protocols for both resins, associated or not with brushing. AP should be recommended when associated with brushing with a Lifebuoy 0.78% solution.

Microbial adhesion and biofilm formation by Candida albicans on 3D-printed denture base resins.

This study evaluated surface properties and adhesion/biofilm formation by Candida albicans on 3D printed denture base resins used in 3D printing. Disc-shaped specimens (15 mm x 3 mm) of two 3D-printed resins (NextDent Denture 3D+, NE, n = 64; and Cosmos Denture, CO, n = 64) and a heat-polymerized resin (Lucitone 550, LU, control, n = 64) were analyzed for surface roughness (Ra µm) and surface free energy (erg cm-2). Microbiologic assays (90-min adhesion and 48-h biofilm formation by C. albicans) were performed five times in triplicate, with the evaluation of the specimens' surface for: (i) colony forming units count (CFU/mL), (ii) cellular metabolism (XTT assay), and (iii) fluorescence and thickness of biofilm layers (confocal laser scanning microscopy). Data were analyzed using parametric and nonparametric tests (α = 0.05). LU presented higher surface roughness Ra (0.329±0.076 µm) than NE (0.295±0.056 µm) (p = 0.024), but both were similar to CO (0.315±0.058 µm) (p = 1.000 and p = 0.129, respectively). LU showed lower surface free energy (47.47±2.01 erg cm-2) than CO (49.61±1.88 erg cm-2) and NE (49.23±2.16 erg cm-2) (p<0.001 for both). The CO and NE resins showed greater cellular metabolism (p<0.001) and CO only, showed greater colonization (p = 0.015) by C. albicans than LU in the 90-min and 48-hour periods. It can be concluded that both 3D-printed denture base resins are more prone to colonization by C. albicans, and that their surface free energy may be more likely associated with that colonization than their surface roughness.

Effect of repair methods and materials on the flexural strength of 3D-printed denture base resin.

PURPOSE: The aim of this study was to evaluate the flexural strength of a 3D-printed denture base resin (Cosmos Denture), after different immediate repair techniques with surface treatments and thermocycling. MATERIALS AND METHODS: Rectangular 3D-printed denture base resin (Cosmos Denture) specimens (N = 130) were thermocycled (5,000 cycles, 5℃ and 55℃) before and after the different repair techniques (n = 10 per group) using an autopolymerized acrylic resin (Jet, J) or a hard relining resin (Soft Confort, SC), and different surface treatments: Jet resin monomer for 180 s (MMA), blasting with aluminum oxide (JAT) or erbium: yttrium-aluminum-garnet laser (L). The control group were intact specimens. A three-point flexural strength test was performed, and data (MPa) were analyzed by ANOVA and Games-Howell post hoc test (α = 0.05). Each failure was observed and classified through stereomicroscope images and the surface treatments were viewed by scanning electron microscope (SEM). RESULTS: Control group showed the highest mean of flexural strength, statistically different from the other groups (P < .001), followed by MMA+J group. The groups with L treatment were statistically similar to the MMA groups (P > .05). The JAT+J group was better than the SC and JAT+SC groups (P < .05), but similar to the other groups (P > .05). Adhesive failures were most observed in JAT groups, especially when repaired with SC. The SEM images showed surface changes for all treatments, except JAT alone. CONCLUSION: Denture bases fabricated with 3D-printed resin should be preferably repaired with MMA+J. SC and JAT+SC showed the worst results. Blasting impaired the adhesion of the SC resin.

Reliability of a method for evaluating porosity in denture base resins.

BACKGROUND: The method of porosity analysis by water absorption has been carried out by the storage of the specimens in pure water, but it does not exclude the potential plasticising effect of the water generating unreal values of porosity. OBJECTIVE: The present study evaluated the reliability of this method of porosity analysis in polymethylmethacrylate denture base resins by the determination of the most satisfactory solution for storage (S), where the plasticising effect was excluded. MATERIALS AND METHODS: Two specimen shapes (rectangular and maxillary denture base) and two denture base resins, water bath-polymerised (Classico) and microwave-polymerised (Acron MC) were used. Saturated anhydrous calcium chloride solutions (25%, 50%, 75%) and distilled water were used for specimen storage. Sorption isotherms were used to determine S. Porosity factor (PF) and diffusion coefficient (D) were calculated within S and for the groups stored in distilled water. anova and Tukey tests were performed to identify significant differences in PF results and Kruskal-Wallis test and Dunn multiple comparison post hoc test, for D results (α=0.05). RESULTS: For Acron MC denture base shape, FP results were 0.24% (S 50%) and 1.37% (distilled water); for rectangular shape FP was 0.35% (S 75%) and 0.19% (distilled water). For Classico denture base shape, FP results were 0.54% (S 75%) and 1.21% (distilled water); for rectangular shape FP was 0.7% (S 50%) and 1.32% (distilled water). FP results were similar in S and distilled water only for Acron MC rectangular shape (p>0.05). D results in distilled water were statistically higher than S for all groups. CONCLUSIONS: The results of the study suggest that an adequate solution for storing specimens must be used to measure porosity by water absorption, based on excluding the plasticising effect.

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.

Measurement of interfacial porosity at the acrylic resin/denture tooth interface.

PURPOSE: Small pores of almost uniform shape and size are common in polymeric materials; however, significant porosity can weaken a denture base resin and promote staining, harboring of organisms such as Candida albicans, and bond failures between the artificial tooth and denture base resin. The aim of this study was to investigate the porosity at the interface of one artificial tooth acrylic resin (Trilux, copolymer of polymethyl methacrylate, ethylene glycol dimethacrylate, and color pigments) and three denture base resins: Acron MC (microwave-polymerized), Lucitone 550 (heat-polymerized), and QC-20 (heat-polymerized). MATERIALS AND METHODS: Ten specimens of each denture base resin with artificial tooth were processed. After polymerization, specimens were polished and observed under a microscope at 80x magnification. The area of each pore present between artificial tooth and denture base resin was measured using computer software, and the total area of pores per surface was calculated in millimeter square. The Kruskal-Wallis test was performed to compare porosity data (alpha= 0.05). RESULTS: Porosity analysis revealed the average number of pores (n), area range (S, mm(2)), and diameter range (d, mum) for Acron MC (n = 23, S = 0.001 to 0.0056, d = 35 to 267), Lucitone 550 (n = 13, S = 0.001 to 0.005, d = 35 to 79), and QC-20 (n = 19, S = 0.001 to 0.014, d = 35 to 133). The analyses showed that there were no statistically significant differences among the groups (p= 0.7904). CONCLUSIONS: Within the limitations of this in vitro study, it was concluded that the denture base resins evaluated did not affect porosity formation at the artificial tooth/denture base resin interface.

Influence of the height of the mandibular ridge on the masticatory function during the functional adaptation with new complete dentures.

BACKGROUND: The period of functional adaptation to a new conventional complete denture embraces many transitory issues, and this period is directly related to the rehabilitation success. OBJECTIVE: This clinical trial evaluated the influence of the height of mandibular ridge on the masticatory function of complete denture (CD) wearers during the adaptation period. METHODOLOGY: A total of 28 individuals wearing new CDs (NR, n=14, normal mandibular ridges, 64±12.5 years, 9 female; RR, n=14, resorbed mandibular ridges, 69±6.8 years, 9 female) were assessed at 24 hours, 30 days, three months and six months after the insertion of the CDs for masticatory performance (MP, sieves method), satisfaction with CDs (questionnaire) and maximum occlusal bite force (MOBF) (gnatodynamometer). The classification of the mandibular ridges followed the Kapur index. Data of MP and MOBF were analyzed by two-way ANOVA and satisfaction with CDs was analyzed by Generalized Estimating Equations (GEE), α=.05. RESULTS: Participants with NR presented better masticatory performance (p=.000 - NR 30.25±9.93%, RR 12.41±7.17%), general satisfaction (p=.047), retention of mandibular denture (p=.001), chewing ability (p=.037), and comfort of wearing a mandibular denture (p=.000). Regardless of the mandibular ridge, MP (p=.000) was higher at three (21.26±12.07%) and six months (24.25±12.26%) in comparison to 24 hours (18.09±10.89%), the MOBF (p=.000) was higher at three months (78.50±6.49 N) compared to 24 hours (57.34±5.55 N) and 30 days (62.72±5.97 N), and the comfort of wearing a mandibular denture (p=.002) at three months (1.61 ± 0.07) was greater than 24 hours (1.29±0.10) and 30 days (1.36±10). CONCLUSIONS: The study suggests that the participants with NR have higher MP and satisfaction with their CD, regardless of the follow-up period after the insertion of the new CD. After subjects received the CD, a period of 3 months was necessary for achieving better achievement MOBF, MP, and self-perceived comfort with the mandibular denture, regardless of the height of the mandibular ridge.

Influence of adhesives usage in complete dentures during adaptation period varying the degree of resorption of mandibular ridges.

PURPOSE: This study evaluated the effect of the use of a powder-type adhesive on masticatory performance and oral health related quality of life (OHRQoL) in patients with normal and resorbed mandibular ridges during adaptation period with complete dentures. METHODS: Forty-two edentulous subjects (12 men, 30 women) were distributed in four groups: normal mandibular ridges with adhesive, n = 10; normal mandibular ridges without adhesive, n = 10; resorbed mandibular ridges with adhesive, n = 11; resorbed mandibular ridges without adhesive, n = 11. Masticatory performance was evaluated by sieving method and OHRQoL by Oral Health Impact Profile in Edentulous Adults (OHIP-EDENT) inventory at 30, 60 and 90 days after the insertion of new complete dentures. Data were analyzed using 2-way ANOVA test and Generalized Estimating Equations (GEEs), α = 0.05. RESULTS: The use of adhesive resulted in better masticatory performance at 30 (35.76 ± 12.63%) and 60 days (30.06 ± 10.54%) after the insertion of the dentures and did not influence on OHRQoL in participants with normal ridges during the adaptation period. The use of adhesive did not interfere on masticatory performance during adaptation period and had a negative effect on masticatory discomfort/disability subscale OHRQoL at 30-day period [5.2(3.6, 6.8)] for resorbed mandibular ridges with new complete dentures. CONCLUSIONS: The use of adhesive can improve masticatory performance of new complete dentures users with normal mandibular ridges in the initial adaptation period up to 60 days after insertion. For resorbed ridges subjects, the use of adhesive had a negative impact on masticatory discomfort/disability OHRQoL at 30 days after insertion.

Maxillary complete denture movement during chewing in mandibular removable partial denture wearers.

OBJECTIVES: To evaluate the pattern of maxillary complete denture movement during chewing for free-end removable partial dentures (RPD) wearers, compared to maxillary and mandibular complete denture wearers. MATERIALS AND METHODS: Eighteen edentulous participants (group I) and 10 volunteers with bilateral posterior edentulous mandibles (group II) comprised the sample. Measures of mean denture movement and its variability were obtained by a kinesiographic instrument K6-I Diagnostic System, during the mastication of bread and a polysulphide block. Data were analysed using two-way ANOVA (alpha = 0.05). RESULTS: Upper movement during chewing was significantly lower for group II, regardless of the test food. The test food did not influence the vertical or lateral position of the denture bases, but more anterior dislocation was found when polysulphide blocks were chewed. Group II presented lower intra-individual variability for the vertical axis. Vertical displacement was also more precise with bread as a test food. CONCLUSION: It can be concluded that mandibular free-end RPD wearers show smaller and more precise movements than mandibular complete denture wearers.

Effect of monomer treatment and polymerisation methods on the bond strength of resin teeth to denture base material.

BACKGROUND: The fracture between acrylic denture base material and artificial teeth is a common clinical occurrence in dental prosthodontic practice. OBJECTIVE: To evaluate the bond strength between acrylic resins and resin denture teeth when submitted by two protocols of monomer liquid application on the tooth surface and using different polymerisation methods. MATERIAL AND METHODS: Microwave-polymerised (Onda-Cryl), heat-polymerised (Clássico) and autopolymerising (Jet) acrylic resins and a brand of resin denture teeth (Biotone) were used. The acrylic resins were polymerised according to the cycles: (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. Thirty specimens were prepared for each polymerisation method; 10 were packed with acrylic resin after 60 s of monomer liquid application on the tooth surface, 10 after 180 s and 10 without any monomer liquid application. For the purpose of the study, a shear test was used. anova and Tukey tests were performed to identify significant differences (alpha = 0.05). RESULTS: The highest bond strength values were found for monomer surface treatments, regardless of the polymerisation cycles. The highest significant values were found for cycles B (15.4 +/- 1.8 MPa), C (11.9 +/- 4.9 MPa) and T (15.4 +/- 2.6 MPa) for non-treated and 60 s methylmethacrylate treated groups. Comparing the monomer liquid treatment, they did not differ significantly (p > 0.05), except for cycle A (p < 0.05). CONCLUSION: Chemical treatment using monomer on the tooth surface prior to the acrylic resin packing improved the bond strength between resin denture tooth and acrylic resin, regardless of monomer liquid treatment protocols. The microwavable resin, polymerised by fast cycle and autopolymerising resin should be avoided for processing denture and denture repairs, respectively.