Vol 14, No 2 (2017)

Published: 2017-08-06

Original Article

  • XML | PDF | downloads: 238 | views: 488 | pages: 62-68

    Objectives:Many advantages have been attributed to dental zirconia ceramics in terms of mechanical and physical properties; however, the bonding ability of this material to dental structure and/or veneering ceramics hasalways been a matter of concern. On the other hand, hydroxyapatite (HA) shows excellent biocompatibility and good bonding ability to tooth structure, with mechanically unstable and brittle characteristics, that make it clinically unacceptable for use in high stress bearing areas. The main purpose of this study was to introduce two simple yet practical methods to deposit the crystalline HA nanoparticles on zirconia ceramics.
    Materials and Methods: zirconia blocks were treated with HA via two different deposition methods namely thermal coating and air abrasion. Specimens were analyzed by scanning electron microscopy, energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD).
    Results: In both groups, the deposition techniques used were successfully accomplished, while the substrate showed no structural change. However, thermal coating group showed a uniform deposition of crystalline HA but in air abrasion method, there were dispersed thin islands of HA.
    Conclusions: Thermal coating method has the potential to significantly alter the surface characteristics of zirconia. The simple yet practical nature of the proposed method may be able to shift the bonding paradigm of dental zirconia ceramics. This latter subject needs to be addressed in future investigations.
    Keywords: Zirconium Oxide; Hydroxyapatites; Dental Bonding; Microscopy, Electron, Scanning; X-Ray Diffraction; Spectrometry, X-Ray Emission

  • XML | PDF | downloads: 285 | views: 518 | pages: 69-75

    Objectives: This study aimed to assess the effect of wet and dry finishing and polishing on microhardness and roughness of microhybrid and nanohybrid composites.
    Materials and Methods: Thirty samples were fabricated of each of the Polofil Supra and Aelite Aesthetic All-Purpose Body microhybrid and Grandio and Aelite Aesthetic Enamel nanohybrid composite resins. Each group (n=30) was divided into three subgroups of D, W and C (n=10). Finishing and polishing were performed dry in group D and under water coolant in group W. Group C served as the control group and did not receive finishing and polishing. Surface roughness of samples was measured by a profilometer and their hardness was measured by a Vickers hardness tester. Data were analyzed using two-way ANOVA (P<0.05).
    Results: The smoothest surfaces with the lowest microhardness were obtained under Mylar strip without finishing/polishing for all composites (P<0.0001). The highest surface roughness was recorded for dry finishing/polishing for all composites (P<0.0001). Dry finishing/polishing increased the microhardness of all composites (P<0.0001).
    Conclusions: Dry finishing and polishing increases the microhardness and surface roughness of microhybrid and nanohybrid composite resins.

     

  • XML | PDF | downloads: 295 | views: 449 | pages: 76-83

    Objectives: The aim of this study was to evaluate the effect of dentin remineralization using proanthocyanidin (PA), fluoride varnish and casein phosphopeptide amorphous calcium phosphate (CPP-ACP) paste and their various combinations on microhardness of demineralized root dentin.
    Materials and Methods: One-hundred and twenty freshly extracted sound human premolars were selected and randomly divided into eight groups for dentin treatment as follows. C: Deionized water (control); PA: 6.5% PA solution; F: fluoride varnish (5% NaF, 22600 ppm fluoride); CP: CCP-ACP; PAF: 6.5% PA + fluoride varnish; PACP: 6.5% PA + CCP-ACP; FCP: fluoride varnish + CCP-ACP and PAFCP: 6.5% PA + fluoride varnish + CCP-ACP. All specimens were subjected to Vickers microhardness test (500 g, 10 seconds, 3 points). Data were analyzed using one-way ANOVA and Tukey’s post hoc test. The significance level was set at 0.05.
    Results: The mean and standard deviation (SD) values of Vickers hardness number (VHN) in groups C, PA, F, CP, PAF, PACP, FCP and PAFCP were 37.39±4.97, 38.68±4.62, 48.28±2.68 ,41.91±3.32, 48.59±2.55, 53.34±2.57, 48.413±4.00 and 55.20±1.82, respectively. Pairwise comparisons of the groups revealed that there was no significant difference between groups C and PA, PA and CP, F and PAF, F and FCP, PAF and FCP, and PACP and FPACP (P>0.05); but significant differences were observed between other groups (P<0.05).
    Conclusions: The results of this study showed that the tested dentin treatments increased the microhardness of demineralized root dentin except for PA application.

     

     

     

  • XML | PDF | downloads: 193 | views: 365 | pages: 84-91

    Objectives: The aim of this study was to evaluate the clinical performance of a packable and a low shrinkage methacrylate-based composite after one year.
    Materials and Methods:In this clinical trial, 50 class I or II restorations were placed in 25 patients. Each patient received two restorations. The tested materials were: (I) Filtek P60 + Single Bond 2 and (II) Kalore GC + Single Bond 2. The restorations were evaluated by two independent examiners after one week (baseline), six months and one year according to the modified United States Public Health Service (USPHS) criteria. The evaluated parameters included color match, marginal adaptation, anatomical form, retention, surface texture, postoperative sensitivity, marginal staining and secondary caries. Data were then analyzed using Friedman and conditional (matched) logistic regression tests at P<0.05 level of significance.
    Results: P60 and Kalore performed similarly at six months and one year (P>0.05). When each composite resin was evaluated independently at baseline and after one year, no statistically significant differences were found except for marginal adaptation (P60) where four restorations were rated Bravo (clinically acceptable). In 8% of restorations, patients expressed postoperative sensitivity.
    Conclusions: Kalore GC and Filtek P60 showed acceptance clinical performance after one year of service.

     

  • XML | PDF | downloads: 244 | views: 491 | pages: 92-99

    Objectives: This study sought to compare the one-year clinical success of a hydrophilic and a hydrophobic fissure sealant in permanent first molars.
    Materials and Methods: This split-mouth clinical trial was conducted on 23 six to nine year olds who had four fully erupted sound first molars. Helioseal-F and Embrace sealants were randomly applied on the first molars, and follow-ups were scheduled at three, six and 12 months to examine the teeth according to USPHS criteria (retention, marginal adaptation, color match, surface smoothness and caries recurrence). The Wilcoxon signed rank test, the Friedman test and the Mann Whitney test were applied for statistical analyses (P<0.05).
    Results: No significant differences were noted between Embrace and Helioseal-F in retention, smoothness of surface, marginal adaptation, color match or caries at three, six or 12 months (all P>0.05). In addition, the retention of sealants between the maxilla and mandible was not significantly different (P>0.05). Friedman test revealed no significant difference in any of the five parameters at different time points in any sealant group (P>0.05).
    Conclusions: Embrace hydrophilic and Helioseal-F hydrophobic sealants have the same one-year clinical success rate.

     

Case Report