The key elements of conducting load-to-fracture mechanical testing on restoration-tooth units in restorative dentistry

Biomimetic restorative dentistry strives to replace lost tooth tissue by biomaterials with similar physical properties. In order to do so, mechanical testing of dental restorative materials on their own and later in dental cavities is highly important. During this process dentists and engineers are collaborating aiming to set the indications of certain restorative materials and application techniques. In vitro fracture resistance testing of a restored tooth is one of the most important tests to be carried out during the indication setting process. However, for this specific test and received results to be valid for clinicians, the group conducting the tests must pay attention to mimic intraoral conditions as much as possible. The article aims at identifying the key elements of fracture resistance tests in dentistry. Adequately conducting this test is a prerequisite for later testing in in vivo conditions the restorative techniques that produced the best results among the in vitro tests

The key elements of conducting load-to-fracture mechanical testing on restoration-tooth units in restorative dentistry

Biomimetic restorative dentistry strives to replace lost tooth tissue by biomaterials with similar physical properties. In order to do so, mechanical testing of dental restorative materials on their own and later in dental cavities is highly important. During this process dentists and engineers are collaborating aiming to set the indications of certain restorative materials and application techniques. In vitro fracture resistance testing of a restored tooth is one of the most important tests to be carried out during the indication setting process. However, for this specific test and received results to be valid for clinicians, the group conducting the tests must pay attention to mimic intraoral conditions as much as possible. The article aims at identifying the key elements of fracture resistance tests in dentistry. Adequately conducting this test is a prerequisite for later testing in in vivo conditions the restorative techniques that produced the best results among the in vitro tests

Bioblock technique to treat severe internal resorption with subsequent periapical pathology: a case report

A variety of therapeutic modalities can be used for the endodontic treatment of a traumatized tooth with internal root resorption (IRR). The authors present a case report of the successful restoration of a traumatized upper central incisor that was weakened due to severe IRR and subsequent periapical lesion formation. A 20-year-old female patient was referred to our clinic with severe internal resorption and subsequent periapical pathosis destroying the buccal bone wall. Root canal treatment had been initiated previously at another dental practice, but at that time, the patient's condition could not be managed even with several treatments. After cone-beam computed tomography imaging and proper chemomechanical cleaning, the tooth was managed with a mineral trioxide aggregate plug followed by root canal filling using short fiber-reinforced composite, known as the Bioblock technique. This report is the first documentation of the use of the Bioblock technique in the restoration of a traumatized tooth. The Bioblock technique appears to be ideal for restoring wide irregular root canals, as in cases of severe internal resorption, because it can uniquely fill out the hollow irregularities of the canal. However, further long-term clinical investigations are required to provide additional information about this new technique.</p

Fatigue failure of anterior teeth without ferrule restored with individualized fiber-reinforced post-core foundations

The aim was to explore the survival of extensively damaged anterior teeth without ferrule restored with different fiber-reinforced composite (FRC) post-core foundations and composite crowns.Sixty extracted upper central incisors were decoronated and randomly divided into four groups (n = 15). After endodontic treatment, the specimens were restored with different individualized fiber-reinforced post-core foundations as follows: control group (CTRL): multiple unidirectional FRC-post + dual-cure composite-core, PFC: multiple unidirectional FRC-post + packable short fiber-reinforced composite (SFRC), BPFC: Bioblock technique with only packable SFRC, BFFC: Bioblock technique with only flowable SFRC. After core build-up, the teeth were finalized with adhesively luted CAD/CAM composite crowns. Cyclic isometric loading (5 Hz) was applied at 100 N for 5000 cycles, and then 200 N and 300 N for 15,000 cycles each in a fluid chamber. The specimens were loaded until fracture occurred or when a total of 35,000 cycles were reached. Kaplan-Meyer survival analysis was conducted, followed by pairwise log-rank post hoc comparisons (Mantel-Cox).The survival rates of the control (8279 cycles) and PFC (6161 cycles) were significantly higher compared to BPFC (3223 cycles) and BFFC (2271 cycles) (p < 0.05). Regarding fracture pattern, nearly all specimens fractured in a restorable manner.For restoring extensively damaged anterior teeth, multiple unidirectional FRC posts are recommended.Although different FRC post/core systems are available for the restoration of damaged root canal treated anterior teeth, multiple unidirectional FRC posts tend to be a good option when the ferrule is missing

Fatigue performance of endodontically treated molars restored with different dentin replacement materials

OBJECTIVES: The aim was to investigate the fatigue performance of endodontically treated (ET) molars restored by various dentin-replacing materials and material configurations. Moreover, the impact of additional adhesive treatment with glass-ionomer cement (GIC) was evaluated.; METHODS: 250 intact molars were collected and randomly distributed into ten groups (n=25). After endodontic procedure standard Class I cavities were prepared and restored with different direct restorative techniques and dentin-replacing materials. Two-group were restored with either packable or flowable short fiber-reinforced composites (SFRCs). Two-group were restored by experimental fiber-reinforced GIC with and without adhesive treatment. Four-group were restored by conventional and resin-modified GICs with or without adhesive treatment. One-group was restored with a dual-cure composite resin and last group was restored with only conventional composite resin (control). Fatigue-survival was measured for all specimens using a cyclic-loading machine until fracture occurred or a number of 40.000 cycles were achieved. Kaplan-Meyer survival analysis was conducted, followed by pairwise log-rank post hoc comparisons. Fracture mode was then examined by means of optical microscopy and SEM.; RESULTS: Group restored with flowable SFRC showed significantly higher survival (p0.05). Group restored with fiber-reinforced GIC had significantly (p<0.05) higher survival rates compared to other commercial GICs. SEM demonstrated change of the fracture line when fracture reached the SFRC layer.; SIGNIFICANCE: Direct restoration of Class I in ET molars with the use of SFRCs as dentin-replacing materials demonstrated its ability to reinforce the dental structures and to increase the fatigue resistance in this specific clinical situation. Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved

Rövid üvegszál megerősítésű kompozit által kifejtett polimerizációs stressz. Előzetes tanulmány

Bevezetés: Kutatásunkban arra kerestük a választ, hogy két eltérő töméstechnika esetében van-e különbség a rövidüvegszál megerősítésű kompozit (short fiber-reinforced composite, SFRC) tömőanyag zsugorodása miatt kialakult repedésekszámában.Anyag és módszer: Két csoportban, 20-20 extrahált bölcsességfogba standardizált nagyságú MOD üreget preparáltunk,majd a fogakat az alábbiak szerint restauráltuk SFRC-vel: 1. csoportnál bulk, rétegzés nélküli technikával, 2. csoportbanpedig ferde rétegzéssel 2 mm vastag rétegekben. Mindegyik minta esetén az SFRC-t 1 mm kompozittal fedtük.A tömés elkészítését követően D-Light Pro lámpával megvizsgáltuk a fogzománcot, és a keletkezett repedések számátrögzítettük. Az összrepedésszámot egy hét elteltével is rögzítettük.Eredmények: A két töméstechnika között az eltérés nem szignifikáns a repedésszám tekintetében. 1 héttel későbba bulk, rétegzés nélküli csoportban 4,95 (340%-os növekedés), a rétegzéses csoportban 4,30 (410%-os növekedés) voltaz átlagos repedésszám. Ez a korábbi adatokhoz képest szignifikáns eltérés (p = 0,000). A két töméstechnika közötta végső összrepedésszám tekintetében nem tapasztaltunk szignifikáns eltérést.Következtetések: SFRC anyag esetén a vizsgált két töméstechnikával közel azonos mértékű repedésképződés jönlétre, és mindkét esetben jelentősen megnő a repedések száma a posztpolimerizációs időszakban

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.</p