Fatigue performance of endodontically treated premolars restored with direct and indirect cuspal coverage restorations utilizing fiber-reinforced cores

Abstract

Objectives The aim of this in vitro study was to investigate the fatigue survival and fracture behavior of endodontically treated (ET) premolars restored with different types of post-core and cuspal coverage restorations. Materials and methods MOD cavities were prepared on 108 extracted maxillary premolars. During the endodontic treatment, all teeth were instrumented with rotary files (ProTaper Universal) to the same apical enlargement (F2) and were obturated with a matched single cone obturation. After the endodontic procedure, the cavities were restored with different post-core and overlay restorations (n = 12/group). Three groups (A1–A3) were restored with either conventional composite core (PFC; control) or flowable short-fiber-reinforced composite (SFRC) core with/without custom-made fiber posts and without overlays. Six groups had similar post-core foundations as described above but with either direct PFC (B1–B3) or indirect CAD/CAM (C1–C3) overlays. Fatigue survival was tested for all restorations using a cyclic loading machine until fracture occurred or 50,000 cycles were completed. Kaplan-Meyer survival analysis was conducted, followed by pairwise post hoc comparisons. Results None of the restored teeth survived all 50,000. Application of flowable SFRC as luting-core material with fiber post and CAD/CAD overlays (Group C3) showed superior performance regarding fatigue survival (p < 0.05) to all the other groups. Flowable SFRC with fiber post and direct overlay (Group B3) showed superior survival compared to all other direct techniques (p < 0.05), except for the same post-core foundation but without cuspal coverage (Group A3). Conclusions Custom-made fiber post and SFRC as post luting core material with or without cuspal coverage performed well in terms of fatigue resistance and survival when used for the restoration of ET premolars. Clinical relevance The fatigue survival of direct and indirect cuspal coverage restorations in ET MOD premolars is highly dependent on whether the core build-up is fiber-reinforced or not. The combination of short and long fibers in the form of individualized post-cores seems to offer a favorable solution in this situation.

Fatigue Resistance of Dissected Lower First Molars Restored with Direct Fiber-Reinforced Bridges—An In Vitro Pilot Study

“…The present study focused on the possible effects of FRC system choice and the remaining bone level on the fatigue resistance of lower dissected molar teeth that were restored with direct, inlay-retained FRC bridges. As in the recent studies carried out by the authors, cyclic loading was used instead of static load-to-fracture testing in this study [ 23 , 30 , 31 ]. When testing the tooth-restoration units, cycling loading is considered to be more suitable to model oral clinical conditions than static testing, as during cyclic loading repetitive forces are generated, which is closer to the conditions of chewing [ 31 ].…”

“…According to the manufacturer’s instructions, fibers should be covered with particulate-filled composites (PFCs) from all directions to avoid moisture uptake from the oral cavity. Yet, more and more studies show that the fracture and fatigue resistance of a restoration can be improved when the flowable SFRC is not covered with PFC [ 30 , 31 , 32 , 33 ]. Thus, the question arises whether SFRCs could be utilized to improve an FRC bridge.…”

Effect of interfacial surface treatment on bond strength of particulate-filled composite to short fiber-reinforced composite

“…Bi-layered composite restorations where flowable SFRC is placed at the cavity bottom as a substructure and veneered with PFC (packable or flowable) have been the recommended technique for restoring stress-bearing posterior teeth as they provided enhancement in load-bearing capacity when tested in vitro [ 9 , 16 ]. In this scenario, surface roughness, surface free-energy, material reactivity, viscosity, the presence of an oxygen inhibition layer, and the increment material employed all have an influence on the bonding between two composite layers [ 19 , 20 ].…”

Biomechanical behaviour and modelling of periodontally compromised teeth restored with fibreglass restorations

“…In addition, the great advantage of this test is that the samples can be tested within a reasonable time (hours), so in terms of time consumption and also clinical relevance, it is positioned between the static load-to-fracture test and the classical dynamic loading test [62,63].…”

“…Mechanical testing was carried out in two phases. In the first phase (pretesting), the restorationtooth units were firstly submitted to an accelerated fatigue-testing protocol [62,63,66,67,68] performed with a dynamic testing machine (Instron ElektroPlus E3000, Norwood, MA, USA) (Figure 19). Cyclic isometric loading was applied on the connector part of the splinted teeth units with a 5 mm wide, round ended metallic tip.…”