Ertan Ertas

Effects of polishing procedures on color stability of composite resins

The purpose of this study was to investigate the effect of different polishing methods on color stability of posterior, universal and nanohybrid composite resin restorative materials upon exposure to a staining agent. Twenty-five specimens were prepared for each of 5 different composite resins (Filtek Z250, Filtek P60, Quadrant LC, Grandio and Filtek Supreme). Specimens were divided into 5 groups and different polishing procedures, including polishing discs (Pd), polishing discs then diamond polishing paste (PdP), polishing discs then a liquid polishing system (Biscover) (PdB), and combinations of these (PdPB) were used. Unpolished specimens served as the control (C). The specimens were stored for 48 h in a coffee solution. The color of all specimens was measured before and after exposure with a colorimeter, and total color change ∆E*) were calculated. The data were analyzed with a two-way ANOVA and the means were compared by Tukey HSD test (α=0.05). The lowest color difference was observed in the groups PdP and C, while the highest color difference was observed in PdPB, and PdB. When comparing the five different restorative materials, no significant difference was observed between FiltekP60 and FiltekZ250, and these materials demonstrated significantly less color change than Quadrant LC and the nanohybrid materials (Grandio, Filtek Supreme). The posterior (Filtek P60) and universal (Filtek Z250) composite resin restorative materials, which do not contain tetraethyleneglycol dimethacrylate (TEGDMA), were found to be less stainable than the nanohybrid (Grandio, Filtek Supreme) and universal (Quadrant LC) composite resins, which contain TEGDMA. The use of diamond polishing paste after polishing with polishing discs significantly decreased staining when compared to the groups that used polishing discs alone, for all restorative materials tested. The highest color change values were obtained for the specimens that were polished with the Biscover liquid polish system (PdB and PdPB groups).

Evaluation of microtensile bond strength of different fissure sealants to bovine enamel.

BACKGROUND The aim of this study was to evaluate the microtensile bond strength (μTBS) of a new fissure sealant and compare it with conventional sealants which are applied to enamel alone, and also with self-etch and etch-and-rinse adhesives. METHODS Enamel specimens were prepared and randomly distributed into three groups according to fissure sealant (Aegis, Helioseal F, Helioseal Clear). Each group was then subdivided according to adhesive system (Clearfil S3, Single Bond, no adhesive). A universal testing machine was used to measure μTBS, and data were analysed using one-way ANOVA and Tukeys tests. RESULTS μTBS values for all Aegis subgroups were significantly lower than for comparable Helioseal F and Helioseal Clear subgroups (p < 0.05). No differences were observed in μTBS of Helioseal F and Helioseal Clear (p > 0.05). In the Helioseal Clear group, μTBS values for Single Bond were significantly higher than for Clearfil S3 (p < 0.05). However, no significant differences were found between the μTBS values of the adhesive subgroups in the Aegis or Helioseal F groups (p > 0.05). CONCLUSIONS Sealant μTBS values may be affected by material content. The addition of an adhesive may improve μTBS values of sealant to enamel.

Human brain mercury levels related to exposure to amalgam fillings

The safety of dental amalgam as the primary material in dental restoration treatments has been debated since its introduction. It is widely accepted that amalgam restorations continuously release elemental mercury (Hg) vapor, which is inhaled and absorbed by the body and distributed to tissues, including the brain. The aim of the present study was to investigate whether the presence of amalgam fillings is correlated with brain Hg level. The Hg levels in the parietal lobes of the brains of 32 cadavers were analyzed with an atomic absorption spectrometer with the mercury hydride system. A total of 32 brain samples were tested; of these, 10 were from cadavers with amalgam fillings, while 22 of them were amalgam free. Hg was detected in 60.0% (6 of 10) of the samples in the amalgam group and in 36.3% (8 of 22) in the amalgam-free group. The average Hg level of the amalgam group was 0.97 ± 0.83 µg/g (minimum: 0.3 µg/g and maximum: 2.34 µg/g), and in the amalgam-free group, it was 1.06 ± 0.57 µg/g (minimum: 0.17 µg/g and maximum: 1.76 µg/g). The results of the present study showed no correlation between the presence of amalgam fillings and brain Hg level.

Clinical evaluation of direct composite restorations and inlays: Results at 12 months

Background: The purpose of this study was to compare the clinical performance of Class II direct and indirect composite restorations according to the United States Public Health Service criteria (USPHS). Materials and Methods: Seventy patients were included and four different composite resins, P60 (FP), SureFil Posterior (SP), Gradia Posterior (GP), and Bisco Aelite LS Packable (BAP) were used as direct restorative material. All of the composite resins except BAP were used as indirect restorative material. Instead of BAP, Tescera Laboratory composites were polymerized in Tescera inlay oven. All restorations were evaluated according to USPHS criteria during a one-year period. Results: There were no statistically significant differences between direct and indirect composite restorations according to the retention, marginal discoloration, surface staining, proximal contact continuity, and secondary caries. Indirect restorations have less surface roughness, postoperative sensitivity (P < 0.05), and soft tissue irritation (P < 0.1) than direct ones. Conclusion: The clinical performances of the indirect restorations were more satisfactory than the direct restorations.

Evaluation of Five Different Desensitizers: A Comparative Dentin Permeability and SEM Investigation

Background/Objective: The purpose of this study was to evaluate the efficacy and durability of five different dentin desensitizers (Gluma Desensitizer Powergel, Bifluorid 12, Gluma Self Etch Bond, D/Sense Crystal, Nupro Sensodyne Prophylaxis Paste with Novamin) on tubule occlusion and dentin permeability reduction in vitro. Method: The quantitative changes in permeability of 100 dentin discs were measured after desensitizer treatments and following post-treatments of 6% citric acid challenge for 1 min or immersion in artificial saliva for 24 hours under hydrostatic pressure generated by a computerised fluid filtration meter. Qualitative SEM analyses were also carried out. Results: Dentin permeability decreased after desensitizer application in all groups. Nevertheless, only the difference between ‘Gluma Self Etch Bond’ and ‘Nupro Sensodyne Prophylaxis Paste with Novamin’ groups was significantly different (p<0.05). Dentin permeability increased significantly after post-treatments (p<0.05). There was no statistically difference among the citric acid-subgroups (p>0.05). Of all the artificial saliva-subgroups, only the difference between ‘D/Sense Crystal’ and ‘Bifluorid 12’ was significantly different (p<0.05). In SEM analysis, morphological changes were detected on the dentin surface and within the tubules following desensitizer treatments and post-treatments. Conclusion: All the desensitizers significantly reduced dentin permeability by changing the morphology of the dentin surface and/or dentinal tubules. Following post-treatments, there was some reduction in the efficacy of the desensitizers which was represented by the reduction in permeability values. SEM analysis revealed some physical changes in the dentin structure which can partly give an explanation to the reduced efficacy of tested desensitizers.