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Showing 3 results for Omati Shabestari

Gh Omati Shabestari, H. Haj Mir Agha, S. Shahabi, R. Bagherpor,
Volume 22, Issue 4 (21 2010)

Background and Aims: Metal-free and fiber-reinforced composite (FRC) restorations have drawn considerable attention and interest in recent years for restoring in the posterior area due to their improved esthetics. Fracture resistance is one of the most important mechanical properties of materials because of 500-600 N load of occlusion. The restorations should tolerate this load. The purpose of this in vitro study was to compare the fracture resistance of FRC with that of zirconia all-ceramic for posterior partial dentures.

Materials and Methods: Forty extracted human intact teeth (20 first premolars and 20 first molars) selected for fabricating 10 pairs of fiber-reinforced composite and 10 pairs of zirconia all-ceramic bridges. After receiving standard tooth preparation, the teeth were mounted with 7.5 mm distance between each other. The bridges were made and cemented on the teeth. Then the restorations were stored in 37ºC water for 30 days. The fracture resistance was measured using mechanical testing machine with cross-head speed of 1mm/min. Data were evaluated by Independent Sample T test.

Results: The mean fracture resistance in the ceramic group was 1329.41 N and for the F.R.C group was 1118.528 N with significant differences between them (P=0.034). The failure modes were mainly cohesive at pontic area for ceramic samples, but adhesive for FRC samples at pontic area.

Conclusion: Both systems showed sufficient fracture resistance for using in posterior area.

R. Ghoveizi, Gh. Omati Shabestari, A. Mirfazaelian, R. Sadrimanesh, A. Mangali,
Volume 23, Issue 1 (22 2010)

A procedure was explained to fabricate a surgical stent to aid the placement of maxillofacial implants for prosthetic auricular rehabilitation. An impression of the defect was made, and a wax pattern of the missing ear completed and evaluated on the patient. The definitive wax prosthesis was processed in clear acrylic resin. Also an occlusal maxillary splint was fabricated and joined to the acrylic resin ear by using an extraoral acrylic resin bar. Surgical stent provides proper orientation of the acrylic resin ear while remaining attached to the maxillary arch. This surgical stent can also be used for radiographic examination.

Abbas Monzavi, Reza Shabanpoor, Marzieh Alikhasi, Ghasem Omati Shabestari,
Volume 25, Issue 4 (9 2013)

Background and Aims: One of the decisive factors on the final esthetic results of implant treatment is the abutment material. Ceramic abutments are nowadays very popular in this regard. The purpose of this study was to compare the fracture resistance of three zirconia abutments with titanium abutment.

Materials and Methods: Four groups of abutments (five specimens in each) were prepared. The abutments were prefabricated titanium, prefabricated zirconia, zirconia-metal, and copy-milled zirconia abutment. After securing the abutments to the implant using a torque of 24 Ncm, they were mounted into a mounting jig using the 30º tilt. The force was applied on the assembly till the failure occured. Facture resistance and mode of failure were recorded for each specimen. The data were analyzed using One-way ANOVA.

Results: The mean values recorded for fracture resistance of different zirconia abutments varied between 426 to 688 N however, there was no significant differences among the groups (P=0.14). Body fracture was observed only in prefabricated zirconia abutments. Screw fracture and screw bending were the common failures observed in other groups.

Conclusion: Zirconia abutments of any type could be successfully used in regular plateform implants.

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