Fracture Behavior of Short Fiber-Reinforced Direct Restorations in Large MOD Cavities

Abstract

The aim of this research was to study the impact of using a short fiber-reinforced composite (SFRC) core on the fatigue performance and fracture behavior of direct large posterior composite restorations. Moreover, the influence of the consistency (flowable or packable) of occlusal composite coverage was assessed. A total of 100 intact molars were collected and randomly distributed into five groups (n = 20). Deep mesio-occlusal-distal (MOD) cavities were prepared in all groups. After adhesive treatment and rebuilding the missing interproximal walls with conventional composite, the specimens in four experimental groups were restored by an SFRC core (everX Flow), which was applied and cured either in bulk or in oblique layers (each 2 mm thick). Packable (G-aenial Posterior) or flowable (G-aenial Injectable) conventional composites were used as a final occlusal layer. The control group was restored with only packable conventional composite. Fatigue survival was measured for all specimens using a cyclic loading machine until a fracture occurred or a total of 25,000 cycles was achieved. Kaplan–Meyer survival analyses were conducted, followed by pairwise log-rank post hoc comparisons. The static load-bearing capacity of surviving teeth was tested using a universal testing machine. Fracture patterns were evaluated visually. There was no statistically significant (p > 0.05) difference in terms of survival between the tested groups. All groups for which flowable SFRC was used showed statistically significantly higher load-bearing capacities compared to the control group (p < 0.05). There were no significant differences regarding fracture resistance among the fiber-reinforced study groups. Regarding the fracture pattern during the survival analysis, all specimens that received SFRC showed a dominantly restorable type of fracture, while the control specimens presented a dominantly non-restorable type. The use of flowable SFRC as a reinforcing core for large MOD direct restorations showed promising achievements regarding fracture behavior.

Fracture Behavior and Integrity of Different Direct Restorative Materials to Restore Noncarious Cervical Lesions

“…The tested specimens were loaded at an angle of 45° to the long axis of the tooth, which is generally used for the mechanical testing of premolar teeth [ 23 ]. First, the restored specimens were pretested and fatigued with cyclic loading during accelerated fatigue testing [ 20 ]. It is known that cycling fatigue loading simulates the clinical situation better compared to static loading, since cyclic forces similar to normal masticatory forces are generated during the testing.…”

“…Mechanical testing was carried out in two phases. In the first phase (pretesting), all restored specimens were submitted to an accelerated fatigue-testing protocol [ 19 , 20 ] by a hydrodynamic testing machine (Instron ElektroPlus E3000, Norwood, MA, USA) at an angle of 135 degrees to the long axis of each tooth ( Figure 2 ).…”

Biomimetic Approach in Tooth Conservation and Fracture Resistance: A Short Descriptive Review of Current Biomaterials and Techniques

“…Fracture resistance: The in vitro restoration of Class II MOD cavities with EverX combined with a 2 mm occlusal layer of conventional composite has been reported to yield superior fracture resistance when compared to a cavity restored with consecutive 2 mm thick oblique increments of packable composite resin [40]. This finding shows that regardless of whether EverX was applied in bulk or in 2 mm increments, it still provides superior resistance [40].…”

“…Fracture resistance: The in vitro restoration of Class II MOD cavities with EverX combined with a 2 mm occlusal layer of conventional composite has been reported to yield superior fracture resistance when compared to a cavity restored with consecutive 2 mm thick oblique increments of packable composite resin [40]. This finding shows that regardless of whether EverX was applied in bulk or in 2 mm increments, it still provides superior resistance [40]. However, other studies following a similar application of EverX below an occlusal layer of conventional composite reported greater mean values for fracture resistance when compared to restorations with conventional composite only; nonetheless, they did not find statistical differences [1,20].…”

Analog and digital modeling of sound and impaired periodontal supporting tissues during mechanical testing

“…Based on the available literature, the embedding material is mainly acrylate resin in in vitro studies. For instance, Technovit 4004 (Heraeus-Kulzer) acrylate resin was used in the studies of the Biomechanical Research Group in Szeged [9][10][11][12][13][14]. The material is available in powder-liquid form.…”