الفهرس | Only 14 pages are availabe for public view |
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. |