Fatigue performance of endodontically treated molars reinforced with different fiber systems.

OBJECTIVE: The aim was to investigate the fatigue performance of root canal-treated (RCT) molars restored with different direct restorations utilizing discontinuous and continuous fiber-reinforced composite (FRC) systems. The impact of direct cuspal coverage was also evaluated. MATERIALS AND METHODS: One hundred and twenty intact third molars extracted for periodontal or orthodontic reasons were randomly divided into six groups (n=20). Standardized MOD, regular cavities for direct restorations were prepared in all specimens, and subsequently, root canal treatment and root canal obturation was carried out. After the endodontic treatment, the cavities were restored with different fiber-reinforced direct restorations as follows: SFC group (control), discontinuous short fiber-reinforced composite (SFC) without cuspal coverage (CC); SFC+CC group, SFC with cuspal coverage; PFRC group, transcoronal fixation with continuous polyethylene fibers without CC; PFRC+CC group, transcoronal fixation with continuous polyethylene fibers with CC; GFRC group, continuous glass FRC post without CC; and GFRC+CC, continuous glass FRC post with CC. All specimens underwent a fatigue survival test in a cyclic loading machine until fracture occurred or 40,000 cycles were completed. The Kaplan-Meier survival analysis was conducted, followed by pairwise log-rank post hoc comparisons between the individual groups (Mantel-Cox). RESULTS: The PFRC+CC group was characterized by significantly higher survival compared to all the groups (p < 0.05), except for the control group (p = 0.317). In contrast, the GFRC group showed significantly lower survival compared to all the groups (p < 0.05), except for the SFC+CC group (p = 0.118). The control group (SFC) showed statistically higher survival than the SFRC+CC group (p < 0.05) and GFRC group (p < 0.05), but it did not differ significantly from the rest of the groups in terms of survival. CONCLUSIONS: Direct restorations utilizing continuous FRC systems (in the form of polyethylene fibers or FRC post) to restore RCT molar MOD cavities performed better in terms of fatigue resistance when CC was performed compared to the same FRC restorations without CC. On the contrary, teeth restored with SFC restorations performed better without CC compared to the ones where SFC was covered. CLINICAL RELEVANCE: In the case of fiber-reinforced direct restorations for MOD cavities in RCT molars, direct CC is recommended when utilizing long continuous fibers for reinforcement, however, should be avoided when only SFC is used for their reinforcement.

Mechanical Performance of Direct Restorative Techniques Utilizing Long Fibers for "Horizontal Splinting" to Reinforce Deep MOD Cavities-An Updated Literature Review.

Excessive cavity preparation and root canal treatment leads to a weakened tooth structure with a lower resistance to fracture. Fiber reinforcement is frequently used to reinforce such teeth, and multiple fiber types and possible applications exist. Various methods for utilizing long fibers to internally splint the remaining cavity walls in the case of large mesio-occluso-distal (MOD) cavities have been proposed; however, no summary of their performance has been written up to now. Our study aims to review the available literature to evaluate and compare the mechanical performance of the different materials and methods utilized for horizontal splinting in large MOD cavities. Three independent authors performed a thorough literature search using PubMed, ScienceDirect, and Google Scholar up until January 2022. The authors selected in vitro studies that used long fibers placed horizontally in posterior teeth with large MOD cavities to reinforce these teeth. From 1683 potentially relevant articles, 11 publications met our inclusion criteria. Seven out of eleven studies showed that horizontal splinting with long fibers improved the fracture resistance of the restored teeth. Three articles showed no significant difference between the fracture resistance of the restored groups. Only one article reported a lower fracture resistance to the horizontally splinted group, compared to conventional direct composite restoration. Within the limitations of this review, evidence suggests that long fiber reinforcement could be used to improve the fracture resistance of heavily restored teeth.

Fracture behaviour of MOD restorations reinforced by various fibre-reinforced techniques - An in vitro study.

PURPOSE: The aim was to evaluate the fracture resistance of various direct restorative techniques utilizing different fibre-reinforced materials for restoring deep class II. MOD cavities in molar teeth. MATERIAL AND METHODS: Two hundred forty intact mandibular third molars were randomly divided into twelve groups (n = 20). Except for the control group (G12), deep mesio-occluso-distal (MOD) cavities were prepared all other groups. After adhesive treatment and rebuilding the missing interproximal walls with composite, the specimen were restored with different fibres and a final occlusal layer of composite as follows: composite only (G1), short fibre-reinforced composite (SFRC) (G2), glass fibre net (GFN) on the base of the cavity bucco-lingually (BL) and SFRC (G3), SFRC and GFN on top of it BL (G4), SFRC and occlusal splinting with GFN (G5), GFN circumferentially and SFRC (G6), polyethylene fibres (PF) on the base of the cavity BL and composite (G7), composite and PF on top of it BL (G8), composite and occlusal splinting with PF (G9), PF circumferentially and composite (G10), transcoronal splinting with PF (G11). Fracture-resistance for the restored teeth were tested using universal-testing machine. Fracture thresholds and fracture patterns were measured and evaluated. RESULTS: The transcoronal splinting (G11) yielded the highest fracture resistance among the restored groups. Groups 1, 3 and 4 showed significantly lower fracture resistance values compared to intact teeth. CONCLUSION: Incorporating polyethylene or a combination of short and bidirectional glass fibres in certain positions in direct restorations seems to be able to restore the fracture resistance of sound molar teeth.

Adhesive dentistry: 2013 and into the future.

With the recent founding of the International Academy for Adhesive Dentistry (IAAD), scientific research, commercially available products, and clinically proven protocols will be brought together with the dental profession.

A systematic approach to deep caries removal end points: the peripheral seal concept in adhesive dentistry.

The objective of this article is to present evidence-based protocols for the diagnosis and treatment of deep caries lesions in vital teeth. These protocols combine caries-detecting dye with anatomical and histologic knowledge to arrive at ideal caries removal end points for adhesive restorations. DIAGNOdent laser fluorescence technology can also be used to confirm these end points. These ideal caries removal end points generate a peripheral seal zone that can support long-term biomimetic restorations. A review of the published literature since 1980 on caries, caries diagnosis, and caries treatments and their relationships to adhesive bonding techniques was carried out. Combining anatomical measurements and pathologic and histologic knowledge with caries-detecting dye and DIAGNOdent laser fluorescence technologies can produce ideal caries removal end points for adhesive dentistry without exposing vital pulps.