A New Multi-Axial Functional Stress Analysis Assessing the Longevity of a Ti-6Al-4V Dental Implant Abutment Screw.

This study investigates the impact of tightening torque (preload) and the friction coefficient on stress generation and fatigue resistance of a Ti-6Al-4V abutment screw with an internal hexagonal connection under dynamic multi-axial masticatory loads in high-cycle fatigue (HCF) conditions. A three-dimensional model of the implant-abutment assembly was simulated using ANSYS Workbench 16.2 computer aided engineering software with chewing forces ranging from 300 N to 1000 N, evaluated over 1.

Enhanced Antimicrobial Properties of Polymeric Denture Materials Modified with Zein-Coated Inorganic Nanoparticles.

Background: Polymeric denture materials can be susceptible to colonization by oral microorganisms. Zein-coated magnesium oxide nanoparticles (zMgO NPs) demonstrate antimicrobial activity. The aim of this study was to investigate the antimicrobial effect and adherence of different oral microorganisms on hybrid polymeric denture materials incorporated with zMgO NPs.

Effect of Repressing Lithium Disilicate Glass Ceramics on The Shear Bond Strength of Resin Cements.

Unlabelled: The aim of this study was to investigate the effect of repeated pressing of lithium disilicate ceramic on the shear bond strength (SBS) of three types of resin cement.

Methodology: A lithium disilicate ceramic (IPS e.max Press) was first heat-pressed to form rectangular disk specimens.

The Effect of Repeated Pressing on the Flexural Strength, Color Stability, Vickers Hardness, and Surface Topography of Heat-Pressed Lithium Disilicate.

The aim of this study was to investigate the effect of repressing leftover heat-pressed lithium disilicate material on its mechanical and optical properties. A lithium disilicate ingot (IPS e.max Press, IvoclarVivadent, Schaan, Liechtenstein) shade (A1) low translucency was first heat-pressed to yield ceramic bars and disks.

The effect of thermocyclic aging on color stability of high translucency monolithic lithium disilicate and zirconia ceramics luted with different resin cements: an in vitro study.

Background: High-translucency monolithic zirconia were developed to combine the esthetics of all ceramic restorations with the strength properties of zirconia. The purpose of this study was to compare the color stability of high-translucency monolithic zirconia ceramics with lithium disilicate luted using light-cure versus dual-cure resin cements following thermocyclic aging.

Methods: Forty specimens, each composed of 10 × 10 × 1 mm ceramic slice luted to dentin surface of an extracted tooth, were prepared and assigned into four groups (n = 10) as follows; LiDi/LC: lithium disilicate luted by light-cure resin cement; LiDi/DC: lithium disilicate luted by dual-cure resin cement; Zr/LC: zirconia luted by light-cure resin cement; and Zr/DC: zirconia luted by dual-cure resin cement.

Repair bond strength of dental computer-aided design/computer-aided manufactured ceramics after different surface treatments.

Objective: To evaluate the microtensile bond strength of four dental computer-aided design/computer-aided manufactured (CAD/CAM) ceramics after application of four different surface treatments.

Materials And Methods: Four dental CAD/CAM ceramics were tested: feldspathic ceramic (VITABLOCKS-Mark II), polymer-infiltrated ceramic network (VITA ENAMIC), zirconia-reinforced lithium silicate (VITA SUPRINITY), and yttria-stabilized zirconia (VITA YZ T). Four surface treatments were applied: no treatment, 5% hydrofluoric acid-etching, airborne particle abrasion, and tribochemical silica coating.

Variables affecting darbepoetin resistance index in hemodialysis patients.

Erythropoietin resistance index calculation has been used as a tool to evaluate anemia response to erythropoietin therapy. Very little has been reported in its use when using darbepoetin and factors influencing in Arab patients. Darbepoetin resistance index (DRI) was calculated in all our patients using darbepoetin.

Fatigue behaviour of dental composite materials.

Objective: The intent of the project was to evaluate the fatigue behavior of particle and fiber filled dental composites that are fabricated either directly or indirectly using a notched specimen with respect to the number of cycles until failure.

Methods: The materials were five dental composites, three normally cured in the oral cavity (Restolux, Renew and Filtek Supreme), direct processing, and two laboratory produced (BelleGlass, and Tescera), indirect processing. The specimens were 3mmx3mmx25mm bars with a 0.

Rebonding of orthodontic brackets. Part II, an XPS and SEM study.

Objective: The hypothesis of this two-part study is that adhesive systems for bonding orthodontic brackets (ie, two self-etch primers [Transbond and M-Bond] and a conventional phosphoric acid etch [Rely-a-Bond]) would show a difference with respect to rebonded enamel surface morphology and chemical composition.

Materials And Methods: This study examined the enamel surface before and after debonding with scanning electron microscopy and the enamel surface chemical composition for the elements Ca, P, O, F, Si, and C using x-ray photoelectron spectroscopy.

Results: The etching of the two self-etch groups is less aggressive and less uniform than that of phosphoric acid.

Leaching and mechanical properties characterization of dental composites.

The objective of this study was to determine the leaching of Ba, Si, and Sr from four dental composites: Restolux (RX), Micronew (M), Renew (RW), and Choice (C) and to correlate the effects of such leaching with flexure strength and modulus of elasticity. The specimens were 3 x 3 x 25-mm bars, polished with 120- and 240-grit SiC paper, and were aged for 4, 6, and 8 months in artificial saliva, distilled water, and a 50/50 mixture of ethanol and distilled water. Inductively coupled plasma with mass spectroscopy (ICP/MS) was used to determine the ion concentrations after aging.

Changes in prosthetic screw stability because of misfit of implant-supported prostheses.

Purpose: The effect of two levels of prosthesis misfit on prosthetic screw stability was evaluated.

Materials And Methods: Two levels of vertical discrepancies--100 and 175 microns--were introduced between an implant-supported complete denture and the terminal abutment. An implant-supported complete denture without vertical discrepancy served as a control.