Fatigue Behavior of Direct Post-and-core-restored Premolars

Abstract

Evaluation of long-term mechanical behavior of new types of restorations in clinical trials is time-consuming. A partial alternative can be found in experimental fatigue-testing, which simulates accelerated mechanical deterioration. The aim of this study was to determine the feasibility of using fatigue-testing of a complex dental restoration and to evaluate the mechanical fatigue behavior of premolar teeth restored with a titanium alloy post and an amalgam or composite core. Eighty-seven human upper premolar teeth were decoronated, embedded, and restored with a prefabricated post of 1 mm diameter. The teeth were randomly assigned to one of two groups corresponding with a core build-up of amalgam or chemically-cured core composite, respectively. Five to 21 days after restoration, the specimens were subjected to cyclic loading (frequency, 5 Hz), at an angle of 45 degrees to the long axis of the tooth. The boundary technique was used for determination of the mean fatigue strengths of the restorations at 10(4), 10(5), and 10(6) cycles, simulating up to 1-3 years of clinical functioning. Mean fatigue strength was expressed in percentage of initial strength: For 10(4), 10(5), and 10(6) cycles, the results were 66%, 58%, and 52%, respectively, for the amalgam and 62%, 62%, and 53% for the composite group. It is concluded that fatigue-testing of more complex systems is possible, if a suitable testing method is selected. The restorations showed a comparable strength reduction after 10(6) cycles of about 50% of their initial strength. The composite core build-up showed a behavior less predictable than that of the amalgam, which might be attributed to handling parameters.

A Review of Chemical-approach and Ultramorphological Studies on the Development of Fluoride-releasing Dental Adhesives Comprising New Pre-Reacted Glass Ionomer (PRG) Fillers

“…Early fatigue tests focused almost exclusively on restorative materials such as amalgam and resin composites [49][50][51][52][53] . To determine the feasibility of a complex dental restoration, Huysmans et al 52) employed a fatigue testing machine (load cycling at 5 Hz frequency) to evaluate the mechanical fatigue behavior of premolar teeth restored with a titanium alloy post and an amalgam or composite core.…”

“…To determine the feasibility of a complex dental restoration, Huysmans et al 52) employed a fatigue testing machine (load cycling at 5 Hz frequency) to evaluate the mechanical fatigue behavior of premolar teeth restored with a titanium alloy post and an amalgam or composite core. The restorations showed a comparable strength reduction of about 50％ of their initial strength after 10 6 cycles.…”

Surface contact fatigue and flexural fatigue of dental restorative materials

“…This approach can be justified since research has shown that composite restorations tend to fail either early, before 10,000 cycles, or very late, after 100,000 cycles. 10 If at a given stress level the sample did not fail within 10,000 cycles, the stress level for the next test sample was increased by a fixed amount of 4% of the clamped fracture strength in the present test. If failure occurred, the stress level for the next sample was decreased accordingly.…”

Adhesive cementation of zirconia posts to root dentin: evaluation of the mechanical cycling effect

“…These fractures are not usually related to an impact, but result from long periods of mechanical fatigue, 11,12 most likely explained by the development of little cracks on tension concentration areas. 13 Static load tests for evaluating failures in restorations have been replaced by mechanical cycling, providing greater accuracy in simulating the loads that act on restorative materials during clinical function.…”