الفهرس 
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Abstract
Summary And Conclusion
In this in vitro study, polymer infiltrated ceramic network ceramics (Vita
Enamic) Endocrowns were constructed. deferent materials were used to
elevation margin. The measurement of the fracture resistance was carried out
after cementation of the Endocrowns with self-adhesive resin cement on the
endodontically treated prepared extracted teeth and after subjection to
thermocycling aging, fracture mode was detected by stereoscopic microscope.
Fifty-four upper premolars teeth were selected with crack and caries-free.
Dimension were selected approximately with the same dimensions with a
standard deviation of ± 10% from the average. Teeth were sound and
extracted for orthodontic or periodontal reasons.
Afterwards all samples were cleaned with ultrasonic scaler*
then immersed
in 70% ethanol solution after extraction for 24 hours[97]. and subsequently
stored in distilled water at room temperature throughout the course of the
study.
Thirty upper first premolar teeth were randomly divided into 3 main
groups according to the type of material used in deep marginal elevation.
1. group E1 control group: n=18 cervical margins were set 2 mm
below cemento-enamel junction (CEJ) and restored directly with
Vita Enamic Endocrown.
2. group E2: n=18 Elevated pulp chamber depth to be 1mm above
CEJ using (SDR)†
, and teeth then were restored with vita Enamic
ceramic Endocrown.*
* SUPRASSO P5 Booster ultrasonic scaler, Mérignac, France
† Dentsply Sirona,USA
Summary
84
3. group E3: n=18 Elevated pulp chamber depth to be 1mm above
CEJ using (RMGI)†
, and teeth then were restored with vita
Enamic ceramic Endocrown.
Then each group was divided into 2 subgroups, 9 samples per group
according to aging thermocycling.
Figure 6
• sub group A without thermocycling.
• subgroups B after thermocycling.
Final restorations were checked for any irregularities and seating of each
restoration was checked with its tooth to final cementation.
After that, all samples were subjected to thermocycling‡
to simulate the
thermal stress to which the restorative materials and the teeth would be
exposed to 10,000 cycles.
Fracture resistance was tested using the universal testing machine showing:
1. Fracture resistance of DME with SDR was found to be higher than
that of the RMGI and control group.
2. No significant difference between endocrowns with DME with
RMGI and control group.
* Figure 6: ceramics VITA ENAMIC blocks (VITA-Zahnfabrik, Bad Säckingen,
Germany)
† Fuji II LC, GC Capsule, America
‡
SD MECHATRONIC THERMOCYCLER GERMANY.
Summary
85
Results:
a. Comparison between DME materials types:
Without thermocycling; there was a statistically significant difference
between fracture resistance of the three groups (P-value <0.001, Effect size =
0.83). Pair-wise comparisons between groups revealed that control group
showed the statistically significantly highest mean fracture resistance. SDR
showed statistically significantly lower mean value. RMGI showed the
statistically significantly lowest mean fracture resistance,
After thermocycling; there was a statistically significant difference between
fracture resistance of the three groups (P-value <0.001, Effect size = 0.53).
Pair-wise comparisons between materials revealed that SDR showed the
statistically significantly highest mean fracture resistance. There was no
statistically significant difference between RMGI and control group, both
showed the statistically significantly lowest mean fracture resistance values,
b. Comparison between non-thermocycled and thermocycled specimens
With SDR, RMGI as well as control groups; non-thermocycled specimens
showed statistically significantly higher mean fracture resistance than
thermocycled specimens (P-value <0.001, Effect size = 0.589), (P-value
<0.001, Effect size = 0.202) and (P-value <0.001, Effect size = 0.866),
respectively.
Summary
86
CONCLUSION
Within the limitations of the study, the following conclusions can be drawn:
1. Fracture resistance of DME with SDR group was found to be higher
than that of the RMGI group and (control group) after thermocycling.
2. Endocrown with DME with SDR is suitable for the clinician, which
may be an alternative to surgical crown lengthening.
3. Endocrown could be acceptable for upper premolar with normal
biting conditions.