Mechanical Evaluation of an Innovative Nano-Ceramic Composite Material for Anterior Endocrown Restorations
Salma Sulaiman Mustafa Al-Ghalayini;
Abstract
Fourteen intact human central incisors were collected and divided into 2 main groups according to the restoration type. In order to evaluate endocrown as a restoration technique used for anterior teeth, it was compared with the conventional method of post, core and crown restoration.
These 2 main groups were then subdivided into 2 subgroups according to the material type. Resin Nano Ceramic (RNC), Lava Ultimate in particular, was the material of interest in this study. Since its categorized within the resin composite materials, we compared it with a ceramic material IPS e-.max which is a glass ceramic.
Finally, these subgroups were subdivided into 2 divisions according to the remaining tooth structure into 0.5 mm and 2 mm above the CEJ.
Our main concern was studying mechanical properties, specifically:
1. Marginal adaptation.
2. Fracture resistance.
3. Mode of failure and restorability.
All the specimens were prepared under the same circumstances. The restorations were all made by CEREC inLab system CAD/CAM.
The marginal vertical discrepancy was measured before and after cementation using the stereomicroscope. Both the restoration technique and the material type didn’t show any statistical significant difference in their gap values neither before nor after the cementation. Only the preparation design had a significant difference, the 2mm specimens had higher vertical marginal values. Thus indicating that more tooth structure increased the frictional resistance and the seating difficulty leading to less adaptation.
The specimens then underwent cyclic loading. The load used was 100N and was applied at an inclined 130 degrees angle just above the cingulum from the palatal surface for 100,000 cycles. The cracks were evaluated twice, once after the first 50.000 cycles then after the second 50,000 cycles.
The material type was the only influencing factor in crack formation. The IPS e.max specimens showed higher number of cracks/unit than the Lava Ultimate, due to the fact that ceramic is a brittle material in comparison to the more resilient composite resin material.
The fracture load of all the specimens was measured after continuous compressive load till failure occurred in a Universal Testing Machine. Again the material type was the only variant with statistical significant difference. IPS e.max needed lower load values to fracture due to the fact that the specimens were already cracked, in comparison to the Lava Ultimate that needed much higher load values to failure.
Finally, the mode of failure and restorability were studied showing that endocrowns were more restorable than crowns, IPS e.max were more restorable than Lava Ultimate, 0.5 mm is more restorable than 2mm.
CONCLUSION
1. Both the restoration technique and the material type seemed to have no effect in the marginal adaptation. The preparation design was the main variant that affected the vertical marginal discrepancy. The less the amount of tooth structure the easier was the seating.
2. The material type was the influencing factor in crack formation, fracture resistance and mode of failure. The resilient RNC material had less surface failure and need higher values of load for fracture thus leading to a more catastrophic failure and less restorability.
3. Endocrown restoration technique is a reliable alternative, which behaves just as good if not even better than the conventional restoration of post, core and crown in the anterior teeth.
4. Lava Ultimate is a promising material with several mechanical advantages due to it resiliency.
These 2 main groups were then subdivided into 2 subgroups according to the material type. Resin Nano Ceramic (RNC), Lava Ultimate in particular, was the material of interest in this study. Since its categorized within the resin composite materials, we compared it with a ceramic material IPS e-.max which is a glass ceramic.
Finally, these subgroups were subdivided into 2 divisions according to the remaining tooth structure into 0.5 mm and 2 mm above the CEJ.
Our main concern was studying mechanical properties, specifically:
1. Marginal adaptation.
2. Fracture resistance.
3. Mode of failure and restorability.
All the specimens were prepared under the same circumstances. The restorations were all made by CEREC inLab system CAD/CAM.
The marginal vertical discrepancy was measured before and after cementation using the stereomicroscope. Both the restoration technique and the material type didn’t show any statistical significant difference in their gap values neither before nor after the cementation. Only the preparation design had a significant difference, the 2mm specimens had higher vertical marginal values. Thus indicating that more tooth structure increased the frictional resistance and the seating difficulty leading to less adaptation.
The specimens then underwent cyclic loading. The load used was 100N and was applied at an inclined 130 degrees angle just above the cingulum from the palatal surface for 100,000 cycles. The cracks were evaluated twice, once after the first 50.000 cycles then after the second 50,000 cycles.
The material type was the only influencing factor in crack formation. The IPS e.max specimens showed higher number of cracks/unit than the Lava Ultimate, due to the fact that ceramic is a brittle material in comparison to the more resilient composite resin material.
The fracture load of all the specimens was measured after continuous compressive load till failure occurred in a Universal Testing Machine. Again the material type was the only variant with statistical significant difference. IPS e.max needed lower load values to fracture due to the fact that the specimens were already cracked, in comparison to the Lava Ultimate that needed much higher load values to failure.
Finally, the mode of failure and restorability were studied showing that endocrowns were more restorable than crowns, IPS e.max were more restorable than Lava Ultimate, 0.5 mm is more restorable than 2mm.
CONCLUSION
1. Both the restoration technique and the material type seemed to have no effect in the marginal adaptation. The preparation design was the main variant that affected the vertical marginal discrepancy. The less the amount of tooth structure the easier was the seating.
2. The material type was the influencing factor in crack formation, fracture resistance and mode of failure. The resilient RNC material had less surface failure and need higher values of load for fracture thus leading to a more catastrophic failure and less restorability.
3. Endocrown restoration technique is a reliable alternative, which behaves just as good if not even better than the conventional restoration of post, core and crown in the anterior teeth.
4. Lava Ultimate is a promising material with several mechanical advantages due to it resiliency.
Other data
| Title | Mechanical Evaluation of an Innovative Nano-Ceramic Composite Material for Anterior Endocrown Restorations | Other Titles | التقيم الميكانيكي للمواد الخزفية بتقنية النانو المبتكرة كتاج ممتد داخل لب الأسنان الأمامية | Authors | Salma Sulaiman Mustafa Al-Ghalayini | Issue Date | 2015 |
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