Titanium implant functionalization with phosphate-containing polymers may favour in vivo osseointegration.

AIM: Osseointegration of titanium implants is predictable, but can be improved via surface functionalization. MATERIALS AND METHODS: One hundred and twenty implants were installed in parietal bone of 12 domestic pigs and left to heal for 1 or 3 months. Five groups were defined according surface treatments: immersion in water (H2 O), 10% polyphosphoric acid (PPA10), 1% phosphorylated pullulan (PPL1), 10% phosphorylated pullulan (PPL10) or 10% phosphorylated pullulan + 1 µg bone morphogenetic protein-2 (PPL10 BMP). As primary outcome, implant osseointegration was evaluated by quantitative histology, namely peri-implant bone formation (B/T in %) and bone-to-implant contact (BIC in %) for each healing period. The Wilcoxon signed-rank test and Mann-Whitney U-test with α = 0.05 were performed. RESULTS: PPL10 and PPA10 groups showed significantly higher B/T and BIC results than the control (H2 O) group at 1-month (p < .05). No significant difference was found between PPL1 and H2 O or between PPL10 BMP and H2 O, irrespective of healing time (1 or 3 months) or investigated parameter (B/T and BIC; p > .05). After 3 months, no experimental group showed a significant difference compared to the control group (H2 O) for both investigated parameters (B/T and BIC; p > .05). CONCLUSION: Functionalizing titanium implants with inorganic or organic phosphate-containing polymers at 10 wt% concentration may stimulate peri-implant bone formation and implant osseointegration at early healing times.

The role of nicotine, cotinine and caffeine on the electrochemical behavior and bacterial colonization to cp-Ti.

Although smoking promotes deleterious effect to bone healing, there is a lack of study investigating its role on the implant structure and biofilm growth. We hypothesized that nicotine, cotinine and caffeine would impair the corrosion resistance of commercially-pure titanium (cp-Ti) and would enhance Streptococcus sanguinis biofilm growth. Neither the smoking products nor the caffeine affected the corrosion tendency (P>.05) and the oxide layer resistance (P=.762) of cp-Ti. Lower capacitance values were noted in the presence of nicotine (P=.001) and cotinine (P=.0006). SEM showed no pitting corrosion, and the EDS spectra did not differ among groups. Nicotine (300µg/mL) induced higher surface roughness (P=.03) and greater surface change of cp-Ti. Nicotine at 3µg/mL, and cotinine at 0.3 and 3µg/mL increased the number of viable cells (P<.05). Biofilm exposed to nicotine (0.3, 3 and 30µg/mL) (P=.025, .030, .040, respectively) and cotinine (3 and 30µg/mL) (P=.027, .049, respectively) enhanced carbohydrate content. Biofilm biomass and protein content were similar among groups (P>.05). These findings suggest a greater biofilm accumulation in smokers, a risk factor that may lead to peri-implantitis.

Discrepancies in marginal and internal fits for different metal and alumina infrastructures cemented on implant abutments.

Cemented crowns are increasingly being used on dental implants instead of on screw-retained prostheses because of the reliability of internal Morse taper implant-abutment connections. However, there is a lack of information on the fit of metal ceramic and premachined alumina infrastructures. Therefore, the aim of this study was to evaluate the marginal and internal fits of different metal and alumina infrastructures cemented on universal post abutments. A total of 45 abutments (6 mm in height and 3.3 mm in diameter) were divided into five groups on the basis of their infrastructure material: cobalt-chromium (CoCr), nickel-chromium (NiCr), nickel-chromium-molybdenum-titanium (NiCrMoTi), gold (Au), and premachined alumina. The alumina group showed marginal overextension, and the Au group showed the highest discrepancy in marginal fit among the metal alloys. The CoCr and alumina groups showed the lowest discrepancies in internal fit. In conclusion, the alumina cylinders exhibited the best internal fit, despite their horizontal overextension. Among the metal alloys, CoCr exhibited the best fit at critical regions, such as the cervical and occlusal areas.

Confocal analysis of the exopolysaccharide matrix of Candida albicans biofilms.

AIM: Confocal laser-scanning microscopy (CLSM) was carried out to investigate the exopolysaccharide matrix of Candida albicans (C. albicans) biofilms developed on denture material under dietary carbohydrate exposure. METHODS: Biofilms were developed on poly(methyl methacrylate) discs in culture media without (control) or with supplementation by glucose or sucrose for 72 h. For the CLSM analysis, biofilms were labeled with concanavalin A (ConA) during its development. Afterwards, biofilms were also labeled with SYTO-9. To confirm the results, the matrix was investigated by the phenol-sulfuric method. Data were analyzed by anova, followed by Tukey's test, with the level of significance set at 5%. RESULTS: The use of ConA during biofilm development provided effective labeling of the exopolysaccharide matrix. The exposure to sucrose resulted in biofilms with the highest exopolysaccharide matrix biovolume (P < 0.05). The characterization obtained by CLSM was confirmed by the phenol-sulfuric method. CONCLUSION: Confocal laser-scanning microscopy was found to be an effective tool for investigating the exopolysaccharide matrix of C. albicans biofilms, and exposure to sucrose resulted in increased matrix production.

Influence of surface free energy of denture base and liner materials on Candida albicans biofilms.

AIM: This study aimed to evaluate the influence of surface free energy (SFE) of denture base and liner materials on Candida albicans biofilm development. METHODS: Discs were fabricated using poly(methyl methacrylate) acrylic resin and poly(ethyl methacrylate) denture liner, according to the manufacturers' instructions. For SFE test, discs were pellicle-coated with saliva alone, saliva + blood plasma, or blood plasma alone. Candida albicans biofilms were allowed to form on pellicle-coated discs for 48 h. Biofilms were evaluated for cell counts, metabolic activity, and structural characteristics at adhesion phase (after 1.5 h of development) and at biofilm maturity (after 48 h of development). Data were analyzed by anova and Tukey tests using a significance level of 5%. RESULTS: Saliva + blood plasma pellicles had a higher SFE compared to pellicles of saliva or blood plasma alone (P < 0.001). Differences in SFE by pellicle-coating did not affect the cell counts, metabolic activity, or structure at the adhesion phase (P > 0.05). In contrast, the presence of blood plasma resulted in higher cell counts, biovolume, and thickness of mature biofilms on both materials (P < 0.001). CONCLUSIONS: Increases in SFE from pellicle-coating leads to robust mature C. albicans biofilms on both denture materials.

Efficacy of calcium hydroxide paste prepared with different vehicles against salivary microbial infiltration of root canals.

This in vitro study evaluated the efficacy of calcium hydroxide Ca(OH)2 pastes prepared with different vehicles in preventing bacterial infiltration in teeth exposed to human saliva. This study used 52 central incisors, of which 4 teeth were used as positive and negative controls (n = 2). The root canals were instrumented and filled with Ca(OH)2 paste prepared with different vehicles: saline solution (Group 1), polyethylene glycol (Group 2), or polyethylene glycol and camphorated paramonochlorophenol (Group 3). Only 6 teeth in Group 1 showed contamination. All teeth in Groups 2 and 3 were contaminated after 32 days of incubation. There were significant differences between Groups 1 and the other groups (P < 0.05) in terms of the mean time to contamination. By contrast, there was no such difference in terms of mean time to contamination between Groups 2 and 3 (P > 0.05). Based on the results, it was possible to conclude that calcium hydroxide paste prepared with saline solution was most effective for retarding microbial contamination.

Inequalities in public water supply fluoridation in Brazil: An ecological study.

BACKGROUND: The literature is scarce on the social and geographic inequalities in the access to and implementation of the fluoridation of public water supplies. This study adds knowledge to the Brazilian experience of the chronic privation of water and wastewater policies, access to potable water and fluoridation in the country. Thus, the aim of this study was to verify possible inequalities in the population's access to fluoridated drinking water in 246 Brazilian municipalities. METHODS: The information on the process of water fluoridation in the municipalities and in the macro region in which each municipality is located was obtained from the national epidemiological survey which was concluded in 2003. The data relating to the human development index at municipal level (HDI-M) and access to mains water came from the Brazilian Human Development Atlas, whilst the size of the population was obtained from a governmental source. The Fisher exact test (P < 0.05) was employed to identify significant associations between the explanatory variables and their ability to predict the principal outcomes of interest to this study, namely the presence or absence of the water fluoridation process in the municipalities as well as the length of time during which this measure has been implemented. Linear regression was used to observe the associations between the relevant variables in a multivariate environment. RESULTS: The results clearly showed that there is a relationship between municipalities with larger populations, located in more socio-economically advantaged regions and with better HDI-M, and where fluoridation is both present and has been implemented for a longer period of time (started before 1990). CONCLUSION: The findings suggest that the aim of treating water with fluoride may not be being adequately achieved, requiring more effective strategies so that access to this measure can be expanded equitably.