الفهرس 
AcknowledgementOnly 14 pages are availabe for public view
 |  | from | 138 |  |  |
| | | from | 138 | | |
Abstract
Teeth were endodontically treated, ten teeth were prepared with 2mm ferrule circumferential and 1mm wide shoulder finish line, with fiber post and composite core to support conventional crowns, this represented group (G E) and other teeth prepared with butt joint design to receive the endocrown restorations, this represented groups (G V & G C).
Teeth were scanned with Cerec Omincam and restoration design with Cerec software, all designed restorations were milled with Cerec MC XL machine. The crowns and endocrowns were seated into the prepared teeth with finger pressure and excess cement was removed with a microbrush. Then, the samples were maintained under a constant pressure of 3 Kg using a specially designed loading device to standardize the load applied during bonding procedure.
All samples were subjected to fracture resistance testing under a compressive load at the center to their long axis using controlled universal testing machine with a load cell of 5kilo newton (KN) and at a crosshead speed of 0.5 mm/min. Data were collected and statistically analyzed. After facture testing, fracture patterns and failure mode of all samples were examined visually and photographed by digital camera.
The following results were obtained from the current study:
The highest mean value of maximum load (Fracture resistance) was recorded with CERASMART endocrowns (1522.64 ± 352.52)N followed by (Vitasuprinity) (1430.36 ± 273.97s)N , the lowest mean value of maximum load (Fracture resistance) was recorded with (E.max crown retained by fiber post) (1301.34 ± 177.12 )N
The results revealed that:
1. Fiber post and composite core with E.max crown showed the least fracture resistance results
2. Both VITASUPRINITY and CERASMART endocrowns showed higher fracture resistance value than fiber post E-max crowns.
3. All groups showed high fracture resistance with non-significant difference “far beyond masticatory forces in the patient’s mouth”
Regarding the failure mode , CERASMART endocrown showed 70% favorable ‘as it is above CEJ’ fracture while ‘fiber post and E-max’ crown and VITASUPRINITY showed 60% favorable fracture patte.