Marginal gap distance and cyclic fatigue loading for different all-ceramic endocrowns

Area of Science:

• Dental Materials Science
• Biomaterials Engineering
• Restorative Dentistry

Background:

• Endocrowns are a minimally invasive restorative option for endodontically treated molars.
• Glass ceramics are widely used for endocrown fabrication due to their aesthetic and mechanical properties.
• Fabrication technique can significantly influence the clinical performance of ceramic restorations.

Purpose of the Study:

• To evaluate the impact of fabrication techniques (pressable vs. machinable) on the marginal gap and fracture resistance of glass ceramic endocrowns.
• To compare lithium disilicate and zirconia-reinforced lithium disilicate glass ceramics.
• To assess the performance of endocrowns after simulated clinical use (cyclic loading).

Main Methods:

• Forty endodontically treated mandibular molars were prepared to receive endocrowns.
• Four groups of endocrowns were fabricated using pressable or machinable lithium disilicate and zirconia-reinforced lithium disilicate glass ceramics (IPS e-max, Celtra).
• Endocrowns were cemented, subjected to 120,000 cycles of fatigue loading, and then tested for marginal gap distance and fracture resistance.

Main Results:

• Significant differences were observed in fracture resistance among all tested ceramic materials (p<0.001).
• Significant differences were found in marginal gap distance, both before and after fatigue loading, across all four ceramic groups.
• CAD/CAM (machinable) fabrication showed higher fracture resistance than heat press fabrication.

Conclusions:

• Endocrowns represent a promising, minimally invasive restoration for root canal treated molars.
• CAD/CAM technology enhances fracture resistance of glass ceramic endocrowns compared to heat press.
• Heat press technology provides superior marginal accuracy for glass ceramic endocrowns compared to CAD/CAM.