Push-out bond strength of MTA HP, a new high-plasticity calcium silicate-based cement

This study was designed to investigate the resistance to dislodgment provided by MTA HP, a new high-plasticity calcium silicate-based cement. Biodentine and White MTA Angelus were used as reference materials for comparison. Three discs 1 ± 0.1 mm thick were obtained from the middle third of the roots of 5 maxillary canines. Three 0.8-mm-wide holes were drilled on the axial surface of each root disc. Standardized irrigation was performed. Then the holes were dried with paper points and filled with one of the three tested cements. The filled dental slices were immersed in a phosphate-buffered saline (PBS) solution (pH 7.2) for 7 days before the push-out assessment. The Kruskal-Wallis test was applied to assess the effect of each endodontic cement on the push-out bond strength. Mann-Whitney with Bonferroni correction was used to isolate the differences. The alpha-type error was set at 0.05. All specimens had measurable push-out values and no premature failure occurred. There were significant differences among the materials (p <0.05). The Biodentine specimens had the highest push-out bond strength values (p < 0.05). MTA HP had significantly higher bond strength than White MTA (p < 0.05). MTA HP showed better push-out bond strength than its predecessor, White MTA; however, Biodentine had higher dislodgment resistance than both MTA formulations301FUNDAÇÃO CARLOS CHAGAS FILHO DE AMPARO À PESQUISA DO ESTADO DO RIO DE JANEIRO - FAPERJE-26/010.001243/2015; E-26/201.491/201

Salivary pellicles equalise surfaces' charges and modulate the virulence of Candida albicans biofilm

Numerous environmental factors influence the pathogenesis of Candida biofilms and an uderstanding of these is necessary for appropriate clinical management. Aims: To investigate the role of material type, pellicle and stage of biofilm development on the viability, bioactivity, virulence and structure of C. albicans biofilms. Methods: The surface roughness (SR) and surface free energy (SFE) of acrylic and titanium discs was measured. Pellicles of saliva, or saliva supplemented with plasma, were formed on acrylic and titanium discs. Candida albicans biofilms were then generated for 1.5 h, 24 h, 48 h and 72 h. The cell viability in biofilms was analysed by culture, whilst DNA concentration and the expression of Candida virulence genes (ALS1, ALS3 and HWP1) were evaluated using qPCR. Biofilm metabolic activity was determined using XTT reduction assay, and biofilm structure analysed by Scanning Electron Microscopy (SEM). Results: Whilst the SR of acrylic and titanium did not significantly differ, the saliva with plasma pellicle increased significantly the total SFE of both surface. The number of viable microorganisms and DNA concentration increased with biofilm development, not differing within materials and pellicles. Biofilms developed on saliva with plasma pellicle surfaces had significantly higher activity after 24 h and this was accompanied with higher expression of virulence genes at all periods. Conclusion: Induction of C. albicans virulence occurs with the presence of plasma proteins in pellicles, throughout biofilm growth. To mitigate such effects, reduction of increased plasmatic exudate, related to chronic inflammatory response, could aid the management of candidal biofilm-related infections

Salivary pellicles equalise surfaces’ charges and modulate the virulence of candida albicans biofilm

Numerous environmental factors influence the pathogenesis of Candida biofilms and an understanding of these is necessary for appropriate clinical management. Aims To investigate the role of material type, pellicle and stage of biofilm development on the viability, bioactivity, virulence and structure of C. albicans biofilms. Methods The surface roughness (SR) and surface free energy (SFE) of acrylic and titanium discs was measured. Pellicles of saliva, or saliva supplemented with plasma, were formed on acrylic and titanium discs. Candida albicans biofilms were then generated for 1.5 h, 24 h, 48 h and 72 h. The cell viability in biofilms was analysed by culture, whilst DNA concentration and the expression of Candida virulence genes (ALS1, ALS3 and HWP1) were evaluated using qPCR. Biofilm metabolic activity was determined using XTT reduction assay, and biofilm structure analysed by Scanning Electron Microscopy (SEM). Results Whilst the SR of acrylic and titanium did not significantly differ, the saliva with plasma pellicle increased significantly the total SFE of both surface. The number of viable microorganisms and DNA concentration increased with biofilm development, not differing within materials and pellicles. Biofilms developed on saliva with plasma pellicle surfaces had significantly higher activity after 24 h and this was accompanied with higher expression of virulence genes at all periods. Conclusion Induction of C. albicans virulence occurs with the presence of plasma proteins in pellicles, throughout biofilm growth. To mitigate such effects, reduction of increased plasmatic exudate, related to chronic inflammatory response, could aid the management of candidal biofilm-related infections66129140COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP007355/2013-002012/07436-

Relationship among malocclusion, number of occlusal pairs and mastication

This study evaluated the relationship among malocclusion, number of occlusal pairs, masticatory performance, masticatory time and masticatory ability in completely dentate subjects. Eighty healthy subjects (mean age = 19.40 ± 4.14 years) were grouped according to malocclusion diagnosis (n = 16): Class I, Class Class II-2, Class III and Normocclusion (control). Number of occlusal pairs was determined clinically. Masticatory performance was evaluated by the sieving method, and the time used for the comminute test food was registered as the masticatory time. Masticatory ability was measured by a dichotomic self-perception questionnaire. Statistical analysis was done by one-way ANOVA, ANOVA on ranks, Chi-Square and Spearman tests. Class II-1 and III malocclusion groups presented a smaller number of occlusal pairs than Normocclusion (p < 0.0001), Class I (p < 0.001) and II-2 (p < 0.0001) malocclusion groups. Class I, and III malocclusion groups showed lower masticatory performance values compared to Normocclusion (p < 0.05) and Class II-2 (p < 0.05) malocclusion groups. There were no differences in masticatory time (p = 0.156) and ability (&#967;2 = 3.58/p= 0.465) among groups. Occlusal pairs were associated with malocclusion (rho = 0.444/p < 0.0001) and masticatory performance (rho = 0.393/p < 0.0001), but malocclusion was not correlated with masticatory performance (rho = 0.116/p= 0.306). In conclusion, masticatory performance and ability were not related to malocclusion, and subjects with Class I, II-1 and III malocclusions presented lower masticatory performance because of their smaller number of occlusal pairs

Long-term efficacy of denture cleansers in preventing Candida spp. biofilm recolonization on liner surface

This study evaluated the long-term efficacy of denture cleansers against Candida spp. biofilm recolonization on liner surface. Specimens were fabricated of a poly(methyl methacrylate)-based denture liner and had their surface roughness evaluated at baseline and after cleansing treatments. C. albicans or C. glabrata biofilms were formed on liner surface for 48 h, and then the specimens were randomly assigned to one of cleaning treatments: two alkaline peroxides (soaking for 3 or 15 min), 0.5% sodium hypochlorite (10 min) or distilled water (control; 15 min). After the treatments, the specimens were sonicated to disrupt the biofilm, and residual cells were counted (cell/mL). Long-term effectiveness of the cleaning processes was determined by submitting a set of cleaned specimens to biofilm growth conditions for 48 h followed by estimation of cell counts. The topography of specimens after cleaning treatments was analyzed by SEM. Data were analyzed by ANOVA and Tukey's test (&#945;; = 0.05). Results of cell count estimation showed significant differences in cleanliness among the treatments (p < 0.001), and it could be observed by SEM. However, no significant difference (p &gt; 0.05) was observed among the Candida species regarding the recolonization condition. Alkaline denture cleansers showed similar cleaning performance and both differed from the control (p < 0.001). Sodium hypochlorite was the only treatment that removed biofilm efficiently, since no viable cells were found after its use. In conclusion, alkaline peroxide denture cleansers were not effective in removing Candida spp. biofilm from denture liner surfaces and preventing biofilm recolonization

Biomechanical evaluation of subcrestal dental implants with different bone anchorages

This study evaluated the biomechanical influence of apical bone anchorage on a single subcrestal dental implant using three-dimensional finite element analysis (FEA). Four different bone anchorage designs were simulated on a posterior maxillary segment using one implant with platform switching and internal Morse taper connection as follows: 2 mm subcrestal placement with (SW) or without (SO) the implant apex engaged into the cortical bone or position at bone level with anchorage only in the crestal cortical (BO) bone or with bicortical fixation (BW). Each implant received a premolar crown, and all models were loaded with 200 N to simulate centric and eccentric occlusion. The peak tensile and compressive stress and strain were calculated at the crestal cortical, trabecular, and apical cortical bone. The vertical and horizontal implant displacements were measured at the platform level. FEA indicated that subcrestal placement (SW and SO) created lower stress and strain in the crestal cortical bone compared with crestal placement (BO and BW models). The SW model exhibited lesser vertical and horizontal implant micromovement compared with the SO and BO models under eccentric loading; however, stress and strain were higher in the apical cortical bone. The BW model exhibited the lowest implant displacement. These results indicate that subcrestal placement decreases the stress in the crestal cortical bone of dental implants, regardless of apical anchorage; however, apical cortical anchorage can be effective in limiting implant displacement. Further studies are required to evaluate the effects of possible remodeling around the apex on the success of subcrestal implants