Mohamed Ayad

Mohamed Ayad
Tanta University · Department of Prosthodontics

BDS, MScD, PhD

About

49
Publications
6,897
Reads
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893
Citations
Introduction
Skills and Expertise
Additional affiliations
March 2002 - present
kau, osu
Position
  • Professor
June 1993 - June 1996
The Ohio State University
Position
  • Researcher
June 1985 - present
Tanta University
Position
  • Head of Department

Publications

Publications (49)
Article
Statement of problem: Studies on the degree of conversion of dental cement in relation to the number of methacrylate components are lacking. Purpose: The purpose of this in vitro study was to evaluate the degree of conversion of single- and multicomponent methacrylate-containing dental cements around opaque and translucent fiber dowels at varyin...
Conference Paper
Objective: Extensively damaged teeth frequently require placement of a core before preparation to receive an indirect restoration. However, the choice of the core material may also influence the outcome although reliable research data are scare. The purpose of this study was to evaluate the effect of using leno woven high modulus polyethylene fiber...
Conference Paper
Objective: Study evaluated the effects of three home bleaching agents on the color stability and surface roughness of posterior, universal and nanohybrid composite resin Method: 75 cylindrical specimens were prepared for 5 different composite (Filtek P60, Filtek Z250, Quadrant LC, Grandio and Filtek Supreme) (n=15). Each group of the 5 composit...
Conference Paper
Objective: Study was to determine the relationship between the total convergence of a complete veneer crown tooth preparation and the mode of cement failure for restorations cemented with conventional and adhesive cements. Method: 120 crowns were cast using Ni-Cr-Be base metal alloy for standardized complete crown tooth preparations on extracted...
Conference Paper
Objectives: The durability of a restoration is largely based on maintenance of the tooth/restoration interface which may lead to marginal integrity breakdown, microleakage, and staining and secondary caries. The purpose of this study was to determine if fluorinated dental bonding resins will reduce composite resin marginal microleakage. Methods:...
Conference Paper
Objectives: Dentin bonding resins generally based upon All-Bond 2 (AB, Bisco) and OptiBond Solo Plus (OB, Kerr) were formulated using fluorinated TEGDMA, TEGDMA, bis-EMA, and HEMA. The purpose of this study was to measure and compare water sorption and solubility among experimental resins with various concentration of F-TEGDMA (F-T) and commercial...
Article
To compare the laboratory bond strengths of three different types of fiber-reinforced composite dowel systems in three different locations of prepared root canal dentin. 60 human extracted intact upper central incisors were selected. The coronal aspect of each tooth was removed, and the remaining root received endodontic therapy. The roots were div...
Conference Paper
Objective: The purpose of this study was to examine the bonding of NEUN (P) and an experimental bis-EMA composite resin (E) with fluorinated TEGDMA (F-T) to enamel and dentin using experimental bonding resins, containing F-T. Method: TEGDMA, bis-EMA, HEMA, OptiBond SoloPlus (OB) and All-Bond 2 (AB) Light-curable, filled (f) and unfilled (u) bondi...
Conference Paper
Objective: This study characterized the elemental composition of an as-received and recast high noble alloy and to examine the in vitro marginal accuracy of complete cast crowns with 3 different marginal configurations. Method: Ninety standardized high noble alloy complete crowns were made on epoxy resin dies duplicated from 3 metal master dies w...
Conference Paper
Objectives: Convergence angles for complete crown preparations have been recommended at 4-12 degrees. This study investigated the variability of faculty evaluation on student scores when assessing complete crown tooth preparations at Faculty of Dentistry, King Abdulaziz University, Saudi Arabia. Methods: The convergence angles of 70 tooth prepara...
Conference Paper
Objective: Lactic acid has an etching effect on both enamel and dentin and the possibility of substituting lactic acid for phosphoric acid as an enamel and dentin conditioner might be considered. This study was to determine the effect of lactic acid at various concentrations and etching times on the shear bond strength of brackets before and after...
Article
Fiber-reinforced composite restorations provide excellent esthetics; however, little is known regarding the influence of margin design on marginal fit and fracture resistance for this type of crown. This study evaluated the effect of variations in tooth-preparation design on the marginal fit and compressive fracture resistance of fiber-reinforced c...
Article
Full-text available
To characterize the surface roughness of human dentin prepared with different rotary instruments and its influence on the micro-tensile bond strength (microTBS) of self-etch adhesives. Dentin surfaces were created from mid-coronal sound dentin in extracted, human third molars. The teeth were ground with high-speed diamond, tungsten carbide finishin...
Article
Cypermethrin is a pyrethroid pesticide widely used to combat agricultural pests. However, little information is available about its toxicity in aquatic macroinvertebrates in the context of the Moroccan coastline. In this study, a suite of physiological and behavioral biomarkers for water quality surveillance using mussels are used to characterize t...
Conference Paper
Objectives: The purpose of this study was to characterize the surface roughness and its influence on wettability of teeth prepared for complete veneer crowns with different dental rotary instruments. Methods: Sixty standardized tooth preparations for complete crowns were completed using a modified milling machine on extracted human teeth with diamo...
Article
The expansion of store-and-forward teledermatology into underserved regions of the world has long been hampered by the requirement for computers with Internet connectivity. To our knowledge, this study is one of the first to demonstrate the feasibility of teledermatology using newer-generation mobile telephones with specialized software and wireles...
Article
Unresolved controversy exists concerning the optimum restorative material to reinforce the thin-walled roots of endodontically treated teeth to improve their fracture resistance under occlusal load. This study evaluated the effectiveness of irrigant, dowel type, and root-reinforcing material on the fracture resistance of thin-walled endodontically...
Article
Thin-walled root canals always present a challenge to dentists to select a restorative treatment that does not further weaken the thin tooth structure. The prognosis of dowel and core restorations can be unpredictable. This clinical report describes the treatment of a patient with extensive caries extending into the root canal of an endodontically...
Conference Paper
Objectives: To investigate, by questionnaire, the selection of current materials and techniques in fixed prosthodontics by dental practitioners in the West of Saudi Arabia. In addition, those methods were compared with methods and materials taught in dental schools via second survey sent to the chairpersons of prosthodontic/restorative departments....
Article
Full-text available
To investigate the in vitro effect of polyethylene woven fiber reinforcement of resin composite on the fracture resistance of weakened marginal ridges in molar teeth. 50 sound extracted human mandibular molars were used. Specimens were divided into five groups (n = 10). Group 1: served as a control for comparison; Group 2: Class I cavity preparatio...
Article
To examine the effects of varied dilutions of lactic acid as a root canal irrigant and compare the shear bond strength of Epiphany adhesive sealer to human dentin surface with other solutions deemed to be suitable root canal irrigants. The occlusal surfaces of 60 extracted molar teeth were ground wet and treated with one of the following irrigants:...
Article
To identify how different treatments of the root dentin surface affect the microscopic appearance of the resin composite/glass-ionomer cement-to-dentin interface. The root canals of 70 extracted human single-rooted teeth were enlarged to reduce dentin wall thicknesses to 0.5 mm. The roots were randomly divided into seven test groups (n=10) accordin...
Article
The rationale for using gold alloys is based largely upon their alleged ability to resist corrosion, but little information is available to determine the corrosion behavior of recast alloys. This study characterized the elemental composition of as-received and recast type III gold alloy and examined the in vitro corrosion behavior in two media usin...
Article
Clinical studies have shown that lack of retention is one of the major causes of fixed dental prosthesis failure. The purpose of this study was to determine the relationship between the convergence angle of a complete metal crown tooth preparation and the recementation strength for restorations cemented with conventional and adhesive cements. One h...
Article
Although it is known that different dental rotary instrument types produce distinct surface roughness of the axial walls which may contribute to the clinical performance of a cast restoration, the ideal roughness that produces optimum wetting at the adhesive interface is unclear. The purpose of this study was to characterize the surface roughness a...
Article
Although surface roughness of axial walls could contribute to precision of a cast restoration, it is unclear how the roughness of tooth preparation affects marginal fit of the restoration in clinical practice. The purpose of this study was to describe the morphologic features of dentin surfaces prepared by common rotary instruments of similar shape...
Article
The rationale for using high noble alloys is based largely upon their alleged ability to resist corrosion. However, combining previously cast metal with new alloy might have a detrimental effect on the corrosion behavior of a high noble alloy. The purpose of this study was to characterize the elemental composition of an as-received and recast high...
Article
The objective of this laboratory investigation was to determine the effect of different preparation designs (light chamfer, deep chamfer, and shoulder) and die-making materials (stone and epoxy) on the resulting margin misfit for fiber-reinforced composite crowns using a measuring microscope. Sixty standardized FibreKor crowns were made on stone an...
Article
Bonding ceramic restorations to tooth structure relies on treatment of the ceramic intaglio surface, selection of a suitable resin luting agent, and appropriate treatment of prepared tooth structure. Various ceramic surface treatments have been advocated which produce different topographies and bond strengths, but little information is available to...
Article
Convergence angles for complete crown preparations have been recommended at 4-12 degrees . However, practitioners have difficulty meeting these recommendations. This study measured and compared the convergence angles of tooth preparations for complete crowns prepared at three Colleges of Dentistry: the University of Tanta, Egypt, King Abdulaziz Uni...
Article
Various solutions used to irrigate root canals and remove the smear layer prior to obturation of a root canal affect surface topography and may influence the sealing ability of endodontic therapy, retention of endodontic dowels, and restoration survival. This study microscopically evaluated the effects of varying dilutions of lactic acid on the rem...
Conference Paper
Statement of problem. Various solutions used to irrigate root canals and remove the smear layer prior to obturation of a root canal affect surface topography and may influence the scaling ability of endodontic therapy, retention of endodontic dowels, and restoration survival. Purpose. This study microscopically evaluated the effects of varying dilu...
Article
The effect of combining new and recast metal on the compositional stability of the alloy used and accuracy of the final restoration is not known. This study characterized the elemental compositional stability of as-received and recast type III gold alloy. The effect of combining these alloys on the marginal accuracy of complete cast crowns also was...
Article
Various methods of rotary preparation and conditioning of teeth affect surface topography and may affect the retention of dental restorations. This study microscopically evaluated dentin surfaces prepared by different rotary instruments and etched using several types of acid etchants that have been deemed suitable dentin conditioners. Occlusal surf...
Article
The object of this study was to evaluate retention of complete cast crowns cemented with different luting cements and to determine whether recemented castings are as retentive as when initially placed. Thirty standardized Rexillium III complete crowns were made on extracted human molar teeth prepared with a modified milling machine using convention...
Article
The influence of tin plating on marginal seating and retention of complete cast crowns was evaluated. Thirty-six standardized gold-alloy complete crowns were made on extracted human molar teeth prepared with a modified milling machine using conventional laboratory techniques. The crowns were randomly assigned to two groups according to the treatmen...
Article
Bond strength of luting cements to dentin is a critical consideration for success of cast restorations. This study determined the relationship between surface characteristics of teeth prepared for complete cast crowns and retention of respective cemented restorations. Ninety artificial crowns were cast for standardized complete crown tooth preparat...
Article
The purpose of this pilot study was to determine how lactic acid solution at various concentrations and etching times affected prepared human enamel and dentin surfaces and to assess whether it could be used in place of phosphoric or maleic acid as an etchant. The occlusal surfaces of extracted molar teeth were ground wet with 600-grit silicon carb...
Article
Although surface finish can be a critical variable in clinical performance, there is a dearth of information regarding surface characteristics of teeth prepared for artificial crowns. This study characterized teeth prepared for complete cast restorations using three representative types of rotary instruments. One hundred and five standardized tooth...
Article
The frequency (102 - 105 Hz) dependence of the dielectric properties of lithium rubidium sulphate (LRS) are reported in the vicinity of the transition temperature Tc = 477 K. The a.c. conductivity sigma(omega) shows a strong temperature dependence and weak frequency response. The dielectric constant in this region shows a strong frequency dispersio...
Article
The specific heats Cp of pure and doped crystals of LiRbSO4 were determined over the range 460–540 K. Impurity incorporation of Sm3+, Dy3+ and V3+ generally increased Cp and an upward shift in the phase transition temperature tc was also observed. The change in entropy and enthalpy was estimated for different dopants as well as dopant contents. The...
Article
The effect of γ-irradiation on the incommensurate phase of LiRbSO4 crystals has been studied by measuring the specific heat Cp. As a result of γ-irradiation, the values of Cp decreased and the transition temperature Tc shifted to lower values. The values of ΔH and ΔS decreased with increasing dose rate. The results are explained on the basis of an...
Article
The effect of an applied bias electric field on the temperature variation of Cp has been investigated. The results show a nonlinear variation of the transition temperature between the incommensurate and commensurate phase with the applied field (E). The changes in entropy and enthalpy decrease sharply with E up to about 8 kV/cm, which is the value...
Article
Rozmn. Odkazy na lit Přehl. lit Kand. dis. autoreferát - datum: 1993 autoreferát - rozsah: 21 sd datum obhajoby: 19931111 ČVO: 23-07-9

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