Mohamed Ghazy | Mansoura University (original) (raw)
Papers by Mohamed Ghazy
We sought to evaluate immediate and delayed micro-tensile bond strength of Panavia F2.0 and Multi... more We sought to evaluate immediate and delayed micro-tensile bond strength of Panavia F2.0 and Multilink Sprint resin cement to superficial, deep and cervical dentin. Thirty-six freshly extracted non-carious human molars were sectioned in the mesiodistal direction to expose three different dentin regions including superficial dentin (1 mm below the dentine-enamel junction), deep dentin (1 mm above the highest pulp horn) and cervical dentin (0.5 mm above the cemento-enamel junction and 0.5 mm below the dentine-enamel junction). Resin cements were applied on dentin surfaces and composite blocks were luted under constant seating pressure. Each group was divided into three subgroups according to time intervals. Specimens were sectioned to obtain sticks of 1 mm2 in diameter and subjected to microtensile bond strength testing at a cross head speed of 1 mm/min. Both resin cements showed higher micro-tensile bond strength to superficial dentin than that to deep or cervical dentin (P < 0.001). Micro-tensile bond strengths of Panavia F2.0 were higher than those of Multilink Sprint at different dentin regions (P < 0.001). Immediate micro-tensile bond strengths were higher than those of delayed micro-tensile bond strengths for both resin cements (P < 0.001). It was concluded that resin cements with different chemical formulations and applications yield significantly different micro-tensile bond strengths to different dentin regions.
Journal of Prosthodontics, Jan 1, 2010
Purpose: Resistance of machined crowns to microleakage when cemented with new self-adhesive cemen... more Purpose: Resistance of machined crowns to microleakage when cemented with new self-adhesive cements has not been fully investigated. This study evaluated microleakage of machined crowns milled from porcelain and composite blocks and bonded to teeth with self-adhesive and conventional resin cement.
Materials and Methods: Thirty-two freshly extracted premolars of similar shape and size were sterilized and mounted in resin blocks. Teeth received standard crown preparations with 1-mm circumferential shoulder finish line, flat occlusal surface reduced by 2 mm, and ideal angle of convergence. Prepared teeth were divided into two equal groups and assigned to either porcelain (Vita Mark II, Vident) or composite
(Paradigm MZ100, 3M ESPE) blocks for crown fabrication. Optical impressions were
captured for each tooth with the intraoral camera of a CEREC 3D machine. Crowns were designed and milled from both materials. Each group was then subdivided into two subgroups (n = 8) according to cement used (self-adhesive resin cement, RelyX Unicem, 3M ESPE or resin cement with self-etching adhesive, Panavia F 2.0,Kuraray).
Following seating, a 5-kg weight was applied on the occlusal surface of the crown for 5 minutes. Specimens were then stored in water at 37◦C for 24 hours. Specimens were thermocycled for 3000 cycles between 5◦C and 55◦C, then coated with nail varnish and immersed in a 2.0% basic red fuchsin dye solution for 24 hours. Teeth were then
rinsed and sectioned mesiodistally and assessed under magnification for microleakage.
A five-point scale was used to score degree of microleakage. Data were statistically analyzed with 2-way ANOVA and Kruskal-Wallis nonparametric test.
Results: Crown material had no significant effect on microleakage (p=0.67); however, cement type had a significant effect (p < 0.0001), with Panavia F 2.0 resulting in lower microleakage scores than RelyX Unicem.
Conclusions: Compared to the self-adhesive cement, the resin cement with separate primer/bonding agent resulted in significantly lower microleakage scores, irrespective
of crown material.
Official Journal of the Egyptian Dental Association, Jan 1, 2004
The International journal of prosthodontics, Jan 1, 2006
I n an attempt to obtain a system less susceptible to failure, the galvano-ceramic technique was ... more I n an attempt to obtain a system less susceptible to failure, the galvano-ceramic technique was introduced to obtain a metal framework with the great advantage of completely eliminating casting steps. Fracture resistance is an important criterion for longterm success and depends on many factors, including the luting agent and the type of metal, which has to withstand normal occlusal forces. The purpose of this study was to compare the fracture resistance of galvano-ceramic crowns with that of widely used metal-ceramic crowns after they were cemented to natural premolar teeth with different luting cements.
We sought to evaluate immediate and delayed micro-tensile bond strength of Panavia F2.0 and Multi... more We sought to evaluate immediate and delayed micro-tensile bond strength of Panavia F2.0 and Multilink Sprint resin cement to superficial, deep and cervical dentin. Thirty-six freshly extracted non-carious human molars were sectioned in the mesiodistal direction to expose three different dentin regions including superficial dentin (1 mm below the dentine-enamel junction), deep dentin (1 mm above the highest pulp horn) and cervical dentin (0.5 mm above the cemento-enamel junction and 0.5 mm below the dentine-enamel junction). Resin cements were applied on dentin surfaces and composite blocks were luted under constant seating pressure. Each group was divided into three subgroups according to time intervals. Specimens were sectioned to obtain sticks of 1 mm2 in diameter and subjected to microtensile bond strength testing at a cross head speed of 1 mm/min. Both resin cements showed higher micro-tensile bond strength to superficial dentin than that to deep or cervical dentin (P < 0.001). Micro-tensile bond strengths of Panavia F2.0 were higher than those of Multilink Sprint at different dentin regions (P < 0.001). Immediate micro-tensile bond strengths were higher than those of delayed micro-tensile bond strengths for both resin cements (P < 0.001). It was concluded that resin cements with different chemical formulations and applications yield significantly different micro-tensile bond strengths to different dentin regions.
Journal of Prosthodontics, Jan 1, 2010
Purpose: Resistance of machined crowns to microleakage when cemented with new self-adhesive cemen... more Purpose: Resistance of machined crowns to microleakage when cemented with new self-adhesive cements has not been fully investigated. This study evaluated microleakage of machined crowns milled from porcelain and composite blocks and bonded to teeth with self-adhesive and conventional resin cement.
Materials and Methods: Thirty-two freshly extracted premolars of similar shape and size were sterilized and mounted in resin blocks. Teeth received standard crown preparations with 1-mm circumferential shoulder finish line, flat occlusal surface reduced by 2 mm, and ideal angle of convergence. Prepared teeth were divided into two equal groups and assigned to either porcelain (Vita Mark II, Vident) or composite
(Paradigm MZ100, 3M ESPE) blocks for crown fabrication. Optical impressions were
captured for each tooth with the intraoral camera of a CEREC 3D machine. Crowns were designed and milled from both materials. Each group was then subdivided into two subgroups (n = 8) according to cement used (self-adhesive resin cement, RelyX Unicem, 3M ESPE or resin cement with self-etching adhesive, Panavia F 2.0,Kuraray).
Following seating, a 5-kg weight was applied on the occlusal surface of the crown for 5 minutes. Specimens were then stored in water at 37◦C for 24 hours. Specimens were thermocycled for 3000 cycles between 5◦C and 55◦C, then coated with nail varnish and immersed in a 2.0% basic red fuchsin dye solution for 24 hours. Teeth were then
rinsed and sectioned mesiodistally and assessed under magnification for microleakage.
A five-point scale was used to score degree of microleakage. Data were statistically analyzed with 2-way ANOVA and Kruskal-Wallis nonparametric test.
Results: Crown material had no significant effect on microleakage (p=0.67); however, cement type had a significant effect (p < 0.0001), with Panavia F 2.0 resulting in lower microleakage scores than RelyX Unicem.
Conclusions: Compared to the self-adhesive cement, the resin cement with separate primer/bonding agent resulted in significantly lower microleakage scores, irrespective
of crown material.
Official Journal of the Egyptian Dental Association, Jan 1, 2004
The International journal of prosthodontics, Jan 1, 2006
I n an attempt to obtain a system less susceptible to failure, the galvano-ceramic technique was ... more I n an attempt to obtain a system less susceptible to failure, the galvano-ceramic technique was introduced to obtain a metal framework with the great advantage of completely eliminating casting steps. Fracture resistance is an important criterion for longterm success and depends on many factors, including the luting agent and the type of metal, which has to withstand normal occlusal forces. The purpose of this study was to compare the fracture resistance of galvano-ceramic crowns with that of widely used metal-ceramic crowns after they were cemented to natural premolar teeth with different luting cements.