Fatigue behavior of direct post-and-core-restored premolars

Area of Science:

• Dental Materials Science
• Biomaterials Engineering
• Mechanical Engineering

Background:

• Clinical trials for long-term dental restoration evaluation are lengthy.
• Experimental fatigue testing offers an accelerated method to simulate mechanical deterioration.
• Assessing complex dental restorations requires validated testing methodologies.

Purpose of the Study:

• To establish the feasibility of fatigue testing for complex dental restorations.
• To evaluate the mechanical fatigue behavior of premolar teeth with titanium posts and amalgam or composite cores.

Main Methods:

• Eighty-seven human premolar teeth were restored with titanium posts and either amalgam or composite cores.
• Specimens underwent cyclic loading at 45 degrees to the long axis at 5 Hz.
• The boundary technique determined mean fatigue strengths at 10^4, 10^5, and 10^6 cycles.

Main Results:

• Both amalgam and composite restorations exhibited comparable strength reductions of approximately 50% after 10^6 cycles.
• Amalgam restorations showed 66%, 58%, and 52% of initial strength at 10^4, 10^5, and 10^6 cycles, respectively.
• Composite restorations showed 62%, 62%, and 53% of initial strength at 10^4, 10^5, and 10^6 cycles, respectively, with less predictable behavior.

Conclusions:

• Fatigue testing is a viable method for evaluating complex dental restoration systems.
• Both amalgam and composite cores demonstrate significant, comparable strength reduction after simulated long-term function.
• Handling parameters may influence the predictability of composite core material behavior under fatigue.