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Article
Effect of different partial ferrule locations on the fracture resistance of endodontically treated teeth restored with fiber posts and complete crowns

Author: Haider Hasan Jasim.
Journal: Tikrit Journal for Dental Sciences مجلة تكريت لعلوم طب الاسنان ISSN: 20731213 Year: 2016 Volume: 4 Issue: 1 Pages: 39-49
Publisher: Tikrit University جامعة تكريت

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Abstract

Purpose. The purpose of this in vitro study was to evaluate the effect of partial ferrule locations on the fracture resistance of endodontically treated maxillary canines restored with complete crowns. Material and Methods. Fifty extracted maxillary canines were sectioned 18 mm from their apices, endodontically treated, and divided into 5 groups of 10 teeth each. All groups were prepared with full shoulder crown preparations. the first group having axial wall heights of 2 mm around the preparation circumferences, the axial walls were circumferential, 360 degrees around the preparations (Complete group), the second, third, and forth groups the axial walls were continuous for 180 degrees (one half of the axial tooth structure) of Palatal, Labial, and Proximal groups, and the fifth group all axial tooth structure was sectioned to the level of the preparation shoulder (Level group). All prepared teeth were then restored with quartz fiber posts (RTD), composite resin (Multicore) cores, and complete metal crowns. The fracture resistance was measured in a universal testing machine at 135 degrees to the long axis of the tooth until failure. Data were analyzed by ANOVA and then by Least Significance Difference test (LSD). The mode of failure was determined by visual inspection of all specimens. Results. Significant differences (P<0.05) were found among the mean fracture loads of the test groups, and was 803.7 N, 747.7N, 347.3 N, 386.6 N, and 186.7N for the Complete, Palatal, Labial, Proximal, and Level groups, respectively. When the mode of failure was evaluated, all failure was an oblique palatal to facial root fracture for the groups with remaining coronal tooth structure. In the Level group, post debonding was the predominant mode of failure. Conclusion. The palatal axial wall was more effective than the labial or proximal axial wall in providing fracture resistance to force applied to the palatal aspect in endodontically treated teeth.


Article
Assessment of the fracture strength of straight and pre-angled (17°) zircon implant abutments supported CADCAM zerconium restoration: An in(vitro study).

Authors: Zardasht N. Abdulghafoor --- Talal H. Al-salman --- Allaa Y. Daham
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2016 Volume: 16 Issue: 1 Pages: 77-83
Publisher: Mosul University جامعة الموصل

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Abstract

Aims :evaluate the effect of abutment angulation on fracture strength of pre-fabricated zircon implant abutment supported CADCAM zircon crown. Material and methods: Ten analog with 3.75×14mm were placed into resin blocks divided in to 2 groups: group A (n=5) parallel to long axis and group B (n= 5) fixed at angulation (17°) to long axis. Then ten abutments were tightened to 25 N/cm2. Ten full anatomic zircon (CAD/CAM) crowns constructed as upper right central incisor: 5 on each group. After luting all crowns with dual cure resin-based luting, all samples passed to artificial aging using thermocycling machine, 500 cycles at (5 to 55 C°±2) degree. Then the load was applied by universal testing machine at 30 degree to the long axis until fracture occurred. Results: Statistical analysis showed that the implant abutment angulations significantly (p < 0.05) reduced the fracture resistance of zircon implant abutment. Conclusions: Within the limitation of this in vitro study it may be concluded that: the fracture strength of zircon implant abutment supported CADCAM zircon crown is significantly reduced in respect to the angulation fromstraight to angulated (17°) zircon abutment.

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