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

Abstract

The aim of this research was to evaluate the mechanical impact of utilizing different fiber-reinforced composite (FRC) systems to reinforce inlay-retained bridges in dissected lower molars with different levels of periodontal support. A total of 24 lower first molars and 24 lower second premolars were included in this study. The distal canal of all molars received endodontic treatment. After root canal treatment, the teeth were dissected, and only the distal halves were kept. Standardized class II occluso-distal (OD) (premolars) and mesio-occlusal (MO) (dissected molars) cavities were prepared in all teeth, and premolar–molar units were created. The units were randomly distributed among four groups (n = six/group). With the aid of a transparent silicone index, direct inlay-retained composite bridges were fabricated. In Groups 1 and 2, both discontinuous (everX Flow) and continuous (everStick C&B) fibers were used for reinforcement, while in Groups 3 and 4, only discontinuous fibers (everX Flow) were used. The restored units were embedded in methacrylate resin, simulating either physiological periodontal conditions or furcation involvement. Subsequently, all units underwent fatigue survival testing in a cyclic loading machine until fracture, or a total of 40,000 cycles. Kaplan–Meyer survival analyses were conducted, followed by pairwise log-rank post hoc comparisons. Fracture patterns were evaluated visually and with scanning electron microscopy. In terms of survival, Group 2 performed significantly better than Groups 3 and 4 (p < 0.05), while there was no significant difference between the other groups. In the case of impaired periodontal support, a combination of both continuous and discontinuous short FRC systems increased the fatigue resistance of direct inlay-retained composite bridges compared to bridges that only contained short fibers. Such a difference was not found in the case of sound periodontal support between the two different bridges.

Oral micro-electronic platform for temperature and humidity monitoring

“…Furthermore, Exaclear GC is highly appropriate for the layering of composite materials, particularly when light-curing is necessary from the palatal side. Moreover, its efficacy extends to bite registration and the facilitation of the transfer of brackets and fibers from the model to the oral cavity 52 – 54 . Vinyl polysiloxane compounds have a significant impact on the field of dentistry due to their extensive range of applications, exceptional biocompatibility, and adherence to high safety standards.…”

Effect of Long Glass Fiber Orientations or a Short-Fiber-Reinforced Composite on the Fracture Resistance of Endodontically Treated Premolars

“…Different materials and techniques including post and core, partial or full crowns, direct composite, amalgam, or ceramic restoration can be applied for the ETPs. The cuspal Polymers 2024, 16, 1289 2 of 14 coverage technique has been stated as a successful indirect technique to prevent the cuspal deflection that occurs in ETPs. In cases of the absence of coronal dentin walls, postcore application can be applied to increase the retention of the restoration [3].…”

“…The properties of pre-impregnated fibers for the reinforcement of composites and the enhancement of the flexural strength of fixed or removable polymethyl methacrylate dentures have received increasing attention since the start of their development [15,16]. everStick ® C&B fibers (GC Corporation, Tokyo, Japan) are pre-impregnated with a lightpolymerizable dimethacrylate resin system.…”

“…These continuous and long fibers contain linear polymer phases that form a semi-interpenetrating polymer network after polymerization. It has been reported that these unidirectional, continuous, long fibers reinforce the teeth as they provide anisotropic mechanical properties [16]. These fibers can also strengthen the teeth when used in different orientations and improve fracture resistance [17].…”

“…Thus, the effect of different application techniques and fiber types on the direct restoration of endodontically treated teeth should be investigated. Szabo et al [16] stated that the in case of a clinical situation that allows the use of unidirectional, long, glass fibers, this was the best choice to achieve reinforcement within the structure of restoration in a recent study. To the best of our knowledge, there is no study which compares the effect of different unidirectional, long, glass fiber orientations and short-fiber-reinforced composites on the fracture resistance of ETPs.…”