Jordan University of Science and Technology

About: Jordan University of Science and Technology is a education organization based out in Irbid, Irbid, Jordan. It is known for research contribution in the topics: Population & Medicine. The organization has 7582 authors who have published 13166 publications receiving 298158 citations. The organization is also known as: JUST.

Cephalometric measurements and facial deformities in subjects with beta-thalassaemia major.

Abstract: This study was performed to identify cephalometric and facial features of patients with beta-thalassaemia major. A total of 54 thalassaemic subjects were examined for craniofacial deformities, including 37 patients (24 males and 13 females, aged 5-16 years) who had lateral cephalometric radiographs. The thalassaemic groups were compared with a normal control group matched for sex and dental age, using a t-test. All thalassaemic patients had a Class II skeletal base relationship. The average ANB angle was significantly larger than the controls in dental stages 2 and 3 (P < 0.05). Mandibular base length (Ar-Gn) was significantly less in thalassaemic patients than in controls, with the greatest differences (P < 0.001) found in the younger age group. The maxilla was of normal length (PNS-ANS, Ptm'-ANS') and appeared prominent (3.3 mm in males and 5.1 mm in females) due to a reduced cranial base length (Ar'-S') and a short mandible (Ar'-P'). Vertically, thalassaemic patients showed a significantly increased maxillary/mandibular planes angle in all groups, with differences ranging between 6.19 and 12.55 degrees (P < 0.001). Thalassaemic patients also showed a reduced posterior facial height (S-Go, Ar-Go) and increased anterior facial proportions. Of the 54 thalassaemic patients examined, 17 per cent had severe facial disfigurements (grade 3).

Porcelain Fracture Resistance of Screw-Retained, Cement-Retained, and Screw-Cement-Retained Implant-Supported Metal Ceramic Posterior Crowns

Abstract: Purpose: The purpose of this in vitro study was to compare the porcelain fracture resistance between screw-retained, cement-retained, and combined screw-and cement-retained metal-ceramic (MC) implant-supported posterior single crowns; and to investigate the effect of offsetting the occlusal screw-access opening on porcelain fracture resistance of screw-retained and cement-retained MC implant-supported posterior single crowns.Materials and Methods: Forty standardized MC molar-shaped restorations were fabricated. The 40 restorations were divided into four groups (SRC, SRO, CRP, and CSC) of 10 specimens each. Group SRC: screw-retained, screw-access hole placed in the center of the occlusal surface; Group SRO: screw-retained, screw-access hole placed 1 mm offset from the center of the occlusal surface toward the buccal cusp; Group CRP: cement-retained, zinc phosphate cement was used; Group CSC: cement-retained with a screw-access hole in the center of the occlusal surface. The screw-retained restorations and abutments were directly attached to 3i implant fixtures embedded in acrylic resin blocks. Subsequently, all test specimens were thermocycled and vertically loaded in a universal testing machine at a crosshead speed of 2 mm/min until fracture. Mean values of load at fracture (in N) were calculated in each group and compared with a one-way ANOVA and Tukey's Studentized test (alpha = 0.05).Results: Mean values of loads required to fracture the restorations were as follows (N): Group SRC: 1721 +/- 593; Group SRO: 1885 +/- 491; Group CRP: 3707 +/- 1086; Group CSC: 1700 +/- 526. Groups SRC, SRO, and CSC required a significantly lower force to fracture the porcelain than did the CRP group (p < 0.05).Conclusion: The cement-retained restorations showed significantly higher mean fracture loads than the restorations having screw-access openings in their occlusal surface. The position of the screw-access hole within the occlusal surface did not significantly affect the porcelain fracture resistance.