Ferrule-Effect Dominates Over Use of a Fiber Post When Restoring Endodontically Treated Incisors: An In Vitro Study

Area of Science:

• Restorative Dentistry
• Dental Materials Science
• Biomaterials Engineering

Background:

• Endodontically treated teeth often suffer structural compromise, necessitating robust restoration techniques.
• The ferrule effect, a circumferential cervical dentin collar, is crucial for the mechanical stability of restored teeth.
• Fiber-reinforced posts are commonly used in endodontic restorations, but their benefit in conjunction with a ferrule requires further investigation.

Purpose of the Study:

• To evaluate the influence of the ferrule effect and fiber posts on the survival of restored endodontically treated incisors.
• To compare the fatigue resistance of glass ceramic crowns bonded to composite resin core buildups with or without a fiber post and ferrule.

Main Methods:

• Bovine incisors with and without a 2-mm ferrule were restored with composite resin core buildups, with or without fiber posts.
• All specimens received bonded glass ceramic crowns and underwent accelerated fatigue testing under cyclic loading.
• Survival analysis (Kaplan Meier) was used to compare failure rates between groups.

Main Results:

• No specimens survived the entire 140,000 load cycles.
• Teeth with a ferrule demonstrated significantly higher survival rates compared to the no-ferrule group.
• The presence of a fiber post did not significantly improve survival in the presence of a ferrule.

Conclusions:

• The ferrule effect is a critical factor in enhancing the survival of restored endodontically treated incisors.
• Fiber-reinforced posts did not offer additional survival benefits and were associated with detrimental failure modes, particularly in the absence of a ferrule.
• Restorations without a ferrule and with a fiber post showed initial failures, while the no-post group had a higher percentage of restorable failures.