Thesis (Ph.D.) - Cairo University - Faculty of Oral and Dental Medicine - Department of Prosthodontics

The present study investigated the effect of Ivoclean cleaning paste on the pull out test of saliva contaminated zirconia copings cemented with a bioactive cement Ceramir A total of 36 multi-rooted caries free human maxillary molar teeth were collected. All teeth was positioned perpendicular to the base of a stainless steel cylinder using a custom device and embedded in the cylinder with epoxy resin In order to standardize the preparation of all samples, teeth were machined milled using a multi-function milling machine to achieve a standardized crown preparation of 20 degree total convergence angle and 1 mm circumferential finish line. Each abutment was scanned and the copings were designed using interactive CAD software. An occlusal extension with an occlusal hole was added to the coping design to facilitate the coping removal during the test. Zirconia copings received airborne particles abrasion with 50 æm alumina-oxide (Al2O3 ) particles. Samples were then divide in to 3 groups: Group (I) (n=12): Zirconia Copings cemented with ceramir cement without saliva contamination (control). Group (II) (n=12): Saliva contaminated zirconia copings cemented with Ceramir cement Group (III) (n=12): Application of cleansing paste (Ivoclean) in saliva contaminated zirconia copings cleaned with cleansing paste and cemented with Ceramir cement The tooth surface was cleaned using air-water spray then was gently dried with compressed air. While the zirconia copings in groups 2 and 3 were immersed in saliva for 1m followed by cleaning with air-water spray for 15 sec. and dried with compressed air for another 15 sec. followed by the application of Ivoclean cleaning paste in group 3 zirconia coping samples. A cementation device with 5kg load was used with all zirconia based coping to standardize load application during the cementation procedure. Testing the samples All samples were then subjected to thermocycling 5000 cycle, then the cemented specimens were mounted in a jig attached to a universal testing machine to measure the retentive pull out tensile load of the material. A tensile mode of force was applied via materials testing machine at a crosshead speed of 1 mm/min up to pull out the coping until cement failure. The maximum pull out load was recorded automatically in Newton via the computer software connected to the testing machine. Mode of failure was examined using photos with macrolense digital camera and scanning electron microscope

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