Preparation Ferrule Design Effect on Endocrown Failure Resistance.

Area of Science:

• Restorative Dentistry
• Biomaterials Science
• Dental Mechanics

Background:

• Endocrowns are a viable restorative option for endodontically treated molars.
• The ferrule effect is crucial for enhancing fracture resistance in various dental restorations.
• The impact of ferrule inclusion on the fracture resistance of endocrowns requires further investigation.

Purpose of the Study:

• To evaluate the influence of ferrule preparation on the fracture resistance of mandibular molar endocrowns.
• To compare the fracture load and failure modes of endocrowns with and without ferrule.
• To assess the role of ferrule height (1mm and 2mm) in endocrown stability.

Main Methods:

• Mandibular third molars were prepared to create endocrown preparations with varying ferrule heights (0, 1, and 2 mm).
• Lithium disilicate endocrowns were fabricated using CAD/CAM and cemented with self-adhesive resin luting agent.
• Specimens were subjected to a 45-degree angled load to failure in a universal testing machine.

Main Results:

• Endocrown preparations with ferrule exhibited significantly higher fracture load resistance compared to those without.
• No significant difference in calculated failure stress was found among groups based on bonding surface area.
• All groups demonstrated a high incidence of catastrophic failures, though the 1mm ferrule group showed fewer instances.

Conclusions:

• Ferrule inclusion in endocrown preparations enhances fracture load resistance in mandibular molars.
• While ferrule improves load-bearing capacity, all endocrowns tested had a high rate of catastrophic failures.
• A 1mm ferrule design may offer a compromise between fracture resistance and minimizing catastrophic failures in endocrown restorations.