Scanning electron microscopy assessment of the load-bearing capacity of cad/cam-fabricated molar crowns

Although fiber-reinforced composites are commonly used in dental practice, whether fiber-reinforced crowns and fixed partial dentures can be used as definitive prostheses remains to be determined. This study used scanning electron microscopy to evaluate the load-bearing capacity of non-reinforced and fiber-reinforced composite (FRC) molar crowns prepared by computer-aided design/computer-aided manufacturing (CAD/CAM). The crowns were fabricated from three empirical FRC blocks, one empirical composite block, and one commercial ceramic block. The FRC resin was prepared by mixing BaO silicate particles, E-glass fiber, and dimethacrylate resin. Specimens were divided into five groups (n = 10), differing in the amounts of filler, resin, and fiber. Crowns were statically loaded until fracture. One-way analysis of variance and Tukey’s post hoc multiple comparison tests were used for statistical analyses. The groups showed significant differences in load-bearing capacity; empirical bidirectional FRC resin blocks had the highest capacity, while commercial ceramic blocks had the lowest capacity. Molar crowns formed from FRC resin blocks had higher load-bearing capacity compared to non-reinforced composite resin and ceramic blocks. These results show that fiber reinforcement increased the load-bearing capacity of molar crowns</p

The Effect of Insulin Like Growth Factor-1 on Recovery of Facial Nerve Crush Injury

Objectives The aim of this study is to investigate the efficacy of locally applied insulin-like growth factor 1 (IGF-1) on the recovery of facial nerve functions after crush injury in a rabbit model. Methods The rabbits were randomly assigned into three groups. Group 1 consisted of the rabbits with crush injury alone; group 2, the animals applied saline solution onto the crushed facial nerve and group 3, IGF-1 implemented to the nerve in the same manner. Facial nerve injury was first electrophysiologically studied on 10th and 42nd days of the procedure. The damage to the facial nerves was then investigated histopathologically, after sacrification of the animals. Results In the electrophysiological study, compound muscle action potential amplitudes of the crushed nerves in the second group were decreased. In pathological specimens of the first and second groups, the orders of axons were distorted; demyelination and proliferation of Schwann cells were observed. However, in IGF-1 treated group axonal order and myelin were preserved, and Schwann cell proliferation was close to normal (P<0.05). Conclusion Local application of IGF-1 in a slow releasing gel was found efficacious in the recovery of the facial nerve crush injury in rabbits. IGF-1 was considered worthy of being tried in clinical studies in facial nerve injury cases

A Turkish translation of the Nordic Occupational Skin Questionnaire (NOSQ-2002/LONG) adapted for young workers in high-risk jobs

BackgroundOccupational skin diseases (OSDs) represent 10-40% of all occupational diseases in many industrialized countries. Young workers are frequently exposed to toxic substances and chemicals in the workplace. The occupational conditions of young workers can impose a high level of risk for the occurrence of OSDs. The Nordic Occupational Skin Questionnaire (NOSQ-2002) was developed in English as a new, comprehensive, standardized tool with which to screen for OSDs

Skin disease symptoms and related risk factors among young workers in high-risk jobs

Background. Occupational skin diseases are the one of the most frequent diseases in many industrialized countries. The studies about skin disease ( SD) on young workers were limited. Objectives. In this study, we aim to evaluate the prevalence of SD symptoms and related risk factors among young workers in high-risk occupations

Surface and in vitro properties of Ag-deposited antibacterial and bioactive coatings on AZ31 Mg alloy

AKTAS, SITKI/0000-0002-9143-6752; yalcin, emine/0000-0002-5280-5375; DURDU, SALIH/0000-0002-6288-0926; Aktug, Salim Levent/0000-0001-7755-0279WOS: 000488409900006Ag (silver)-based bioceramic coatings were fabricated on AZ31 Mg alloy by combining the MAO (micro-arc oxidation) and PVD (physical vapor deposition) methods. As a first step, AZ31 Mg surfaces were coated using MAO using a solution consisting of sodium silicate and potassium hydroxide. As a second step, an Ag layer was accumulated on the MAO surfaces using the PVD method. The XRD patterns thus obtained demonstrated the presences of Mg (magnesium), Si (silicon), M2SiO4 (forsterite) and MgO (periclase) on the Ag-deposited MAO surfaces. The elemental or compound structures of Ag were not detected due to the homogeneous distribution of a trace amount of Ag on the surfaces. Both coatings' surfaces were porous due to the existence of discharge channels. All elements were found to be uniformly distributed across the entirety of the surfaces. The Ag-deposited MAO surfaces were found to have hydrophobic properties with respect to plain MAO surfaces. Newly formed layers consisted of Ca-15(SiO4)(6)(PO4)(2) (calcium silicate phosphate), Ca-3(PO4)(2) (tuite) and Ca-10(PO4)(6)(OH)(2) (hydroxyapatite) as produced on plain MAO and Ag-deposited MAO surfaces by immersion in SBF (simulated body fluid); these layers were more homogeneous on Ag-deposited MAO coatings than ones on plain MAO. Also, for E. coli (Escherichia coli) and S. murus (Staphylococcus moms) bacteria, the numbers of active bacterial colonies on Ag-deposited MAO surfaces were significantly reduced with respect to plain MAO surfaces

Fabrication, characterization and in vitro properties of silver-incorporated TiO2 coatings on titanium by thermal evaporation and micro-arc oxidation

AKTAS, SITKI/0000-0002-9143-6752; Aktug, Salim Levent/0000-0001-7755-0279; DURDU, SALIH/0000-0002-6288-0926; Korkmaz, Kemal/0000-0002-4736-275XWOS: 000447106400060In this study, as a first step, a silver (Ag) thin film layer was deposited on cp-Ti (Grade-2) by thermal evaporation-physical vapor deposition (TE-PVD). And then, Ag-based titanium surface was coated by micro-arc oxidation (MAO) in solution, consisting of sodium silicate and potassium hydroxide at the second step. The phase structure, surface morphology, elemental composition, functional groups, wettability and surface topography of both coatings were characterized by XRD, SEM, EDS-mapping, contact angle goniometer, ATR-FTIR and surface profilometer, respectively. The XRD results indicated that anatase and rutile were detected on the surface after MAO and TE + MAO. Both coatings' surfaces were rough and porous due to the existence of plasma chemical reactions on micro discharge channels. The Ag-incorporated MAO coating exhibited much more hydrophilic character than MAO coating. The Ag was homogeneously distributed through the surface. The biological properties such as bioactivity and anti-bacterial tests of the coatings were analyzed by immersion test in SBF and bacterial formation. The apatite-forming abilities of both coatings were evaluated by soaking in simulated body fluid (SBF) up to 28 days. After soaking, apatite structure was formed on the MAO and Ag-incorporated MAO surfaces and the bioactivity of MAO surface on Ti was considerably improved compared to the MAO surface under SBF conditions. The homogenous and dense apatite distribution was observed on Ag-incorporated MAO coatings. The bacterial adhesion of Ag-incorporated MAO coatings was significantly reduced compared to plain MAO surface

Fabrication and in vitro properties of zinc-based superhydrophilic bioceramic coatings on zirconium

AKTAS, SITKI/0000-0002-9143-6752; Aktug, Salim Levent/0000-0001-7755-0279; DURDU, SALIH/0000-0002-6288-0926WOS: 000437391300053In this study, as the first step, the bioceramic coatings were fabricated on Zr (commercial pure zirconium) in calcium acetate and beta-calcium glycerophosphate salt-based electrolyte by MAO (micro arc oxidation). And then, as the second step, the Zn (zinc) thin film layer measured an average thickness of 5 nm was coated on the MAO surface by TE (thermal evaporation). The phase composition, surface and cross sectional morphology, elemental composition and wettability of the MAO and Zn-based MAO coatings were analyzed by powder-XRD and TF-XRD, SEM, EDS-mapping and contact angle goniometer, respectively. The phases of cubic-ZrO2, perovskite-CaZrO3 and HA (hydroxyapatite) were observed on the surfaces by powder and TF-XRD analyses. The morphology of the MAO surface was not changed by TE although the chemistry of it was different from the MAO surface. The surfaces of both coatings were porous and rough. The Zn was uniformly deposited through the whole surface. After TE process, the wettability of the surface decreased and the Zn-based surface exhibited superhydrophilicity compared to MAO surface. In vitro bioactivity test of both coatings were investigated by immersion test in SBF (simulated body fluid) up to 10 days. The bone like apatite layer (secondary apatite) on the Zn-based bioceramic surface was compact and uniform compared the one on the MAO surface although it was completely propagated through both surfaces. In vitro anti-bacterial test of both coatings were carried out by microbial adhesion for Gram positive and Gram negative bacteria. It was observed that the microbial adhesions of the Zn-based bioceramic surfaces were lower than ones of the MAO bioceramic surfaces for all Gram-positive and Gram-negative bacteria.Scientific and Technological Research Council of Turkey (TUBITAK MAG Project) [113M162]A part of this work (MAO production) was supported by the Scientific and Technological Research Council of Turkey (TUBITAK MAG Project - 113M162)

Characterization and investigation of in vitro properties of antibacterial copper deposited on bioactive ZrO2 coatings on zirconium

AKTAS, SITKI/0000-0002-9143-6752; DURDU, SALIH/0000-0002-6288-0926; Aktug, Salim Levent/0000-0001-7755-0279WOS: 000468174200009In this study, porous and rough bioceramic structures were coated on commercial pure Zr by PEO (plasma electrolytic oxidation). Then, Cu was deposited onto the PEO surfaces without any morphological changing by TE (thermal evaporation). Mainly, meta-stable Ca0.15Zr0.85O1.85 (calcium zirconium oxide), cubic-ZrO2 (zirconia) and perovskite-CaZrO3 (calcium zirconate) were observed on the surfaces by powder-XRD (powder X-ray diffraction) and TF-XRD (thin film XRD) analyses as the phases of Zr and Cu-2(P2O7) (copper pyrophosphate) were detected as a trace amount on the Cu-deposited PEO surface. The average thicknesses of the PEO coating and TE layer were measured as approximately 21.8 +/- 2.4 mu m and 20 nm, respectively. The Cu-deposited PEO surfaces indicated superhydrophobic character while the PEO surface exhibited hydrophilic behavior. The apatite-forming abilities on both coatings were evaluated by surface and cross-sectional SEM (scanning electron microscopy) and surface EDS (energy dispersive X-ray spectroscopy)-mapping analyses at post-soaking in SBF (simulated body fluid) up to 10 days. However, apatite formed on the Cu-deposited PEO surfaces was thicker and more homogenous than the PEO surface. Thus, in vitro bioactivity was considerably improved by Cu-deposition on the PEO. In vitro microbial adhesion test of both surfaces was investigated by bacterial adhesions for Gram positive and Gram negative bacteria. The bacterial adhesions on the Cu-deposited PEO surfaces were lower compared to the PEO surfaces for all bacteria types.TUBITAK, TurkeyTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [-113M162]A part of this work (PEO production) was supported by TUBITAK, Turkey (Project Number -113M162)