الفهرس 
Vita EnamicOnly 14 pages are availabe for public view
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Abstract
This study was designed to evaluate the effect of
different preparation designs including non anatomical and
anatomical with different bonding substrate on fracture resistance
of poymer infiltrated ceramic occlusal veneer restorations.
Twenty eight extracted human mandibular molars without
caries or visible fracture lines were selected based on the teeth
having similar bucco-lingual (BL) and mesio-distal(MD)
dimensions.
The selected teeth were divided into 2 main groups according
to the occlusal preparation designs and then each group of teeth
was subdivided into 2 subgroups according to the different
bonding substrate.
For all teeth, the CNC milling machine was adjust to reduce
fourteen teeth with 90º butt margin (flat) and other fourteen
follow the occlusal anatomy of the teeth with an angle 150º
between cusps.
Occlusal veneers were designed by CAD software Exocad
from VITA ENAMIC blocks. The restorations were checked and
polished. Surface treatment of the restorations was performed with
hydrofluoric acid and sialne before cementation with resin
cement. Surface treatment of the teeth was performed by etching
then bonding agent.
Thermal cycling was applied and all samples were loaded in a
universal testing machine until fracture occurred. The fractured
specimens and fragments were collected and mode of fracture
were examined visually and under stereomicroscope at
magnification (6x-8x) to determine different fracture modes.
Two Way ANOVA test was used to examine the effect of
different occlusal preparation desgins and different bonding
substrates on the fracture resistance of Vita Enamic occlusal
veneers. The result revealed that the fracture resistance of non
anatomical preparation designs was significantly higher than the
anatomical preparation designs. The result showed that the
fracture resistance of enamel bonding substrate was significantly
higher than dentin bonding substrate with enamel peripheral.
Evaluation of the failure modes revealed non significant
difference between the modes of failure of tested groups.