Fracture Resistance Of Endodontically-treated Teeth Research Articles

Comparative evaluation of three types of fiber orientation techniques on fracture resistance of endodontically treated premolars restored with composite resin: An in vitro study

ABSTRACT Introduction: A new technique of fiber reinforcement (horizontal + base fiber [HBF]) in the restoration of endodontically treated teeth (ETT) with composite resin was proposed. Aim: This study aims to compare three different types of fiber orientation techniques on fracture resistance of ETT. Materials and Methodology: Sixty intact extracted human maxillary premolars were assigned to five groups (n = 12). Group 1 intact teeth (control). The teeth in Groups 2–5 received endodontic treatment and a MOD cavity preparation and restored with composite resin with polyethylene fiber at different positions. Group 2: No fiber group (NF), Group 3: Occlusal fiber group (OF), Group 4: Horizontal fiber group (HF), and Group 5: HBF group. After thermocycling, the specimens were loaded using a universal testing machine until fracture and the fracture patterns were analyzed. Statistical Analysis: The data were analyzed statistically using analysis of variance with Tukey’s post hoc test (fracture load) and Chi-square test (fracture patterns). Results: Fiber-reinforced groups (OF, HF, HBF) showed significantly higher fracture resistance compared to NF group (P < 0.05). No significant differences in fracture resistance were observed between (a) fiber-reinforced groups (OF, HF, HBF) and intact teeth (P > 0.05) (b) amongst the fiber-reinforced groups (OF, HF, HBF) (P > 0.05). With regard to fracture patterns, no significant differences were observed between the study groups (P > 0.05). Conclusion: Restoring ETT with different techniques of fiber reinforcement resulted in the improvement of the fracture resistance comparable to that of intact teeth. The newly proposed technique of fiber insertion might be considered as an alternative to earlier techniques for the reinforcement of ETT.

Effect of Root Canal Taper on the Ability of Endodontically Treated Teeth using the TruNatomy and Protaper Next File Systems to Resist Fracture.

This research was done to evaluate how the root canal taper affects the Endodontically Treated Teeth (ETT) prepared with the TruNatomy and Protaper Next file systems in terms of fracture resistance. Forty recently extracted mandibular premolar teeth were used in this research, which was classified into four groups at random. Groups 1a and 1b used TruNatomy 4% and 6%, respectively, while groups 2a and 2b used the Protaper Next 4% and 6% file systems, respectively. The root canals were cleaned, shaped, and sealed using cold lateral compaction. The root canals were then fixed in standardized autopolymerizing acrylic resin blocks and tested for vertical root fracture using a universal testing machine. Newtons were used to measure the forces needed to cause fractures. Data were statistically analyzed. In comparison with other groups, group 1a (TruNatomy 4%) displayed greater fracture resistance (423.322.43 Newtons), and group 2b (Protaper Next 6%) displayed the least fracture resistance (264.512.76 Newtons). Protaper Next file system had lower fracture resistance than TruNatomy file system. With the use of greater taper instruments, a notable decrease in the fracture resistance of ETT was observed.

The Influence on Fracture Resistance of Different Composite Resins and Prefabricated Posts to Restore Endodontically Treated Teeth.

Recent formulations of resin-based composites have incorporated different combinations of materials. However, the mechanical and bonding behavior of these materials with intraradicular posts are unclear. This study aimed to evaluate the effect of light-cure and dual-cure resin composite posts on the fracture resistance of endodontically-treated teeth. Materials and Methods: Ninety extracted human upper canines were selected and randomly divided into nine groups (n=10): (G1) endodontically treated teeth without endodontic posts; (G2) glass-fiber post cemented with glass-ionomer cement; (G3) endodontic post by dual-cure composite resin (Rebilda DC); (G4) endodontic post by dual-cure composite resin (Cosmecore); (G5) endodontic post by dual-cure composite resin (Bis-Core); (G6) endodontic post by light-cure composite resin; (G7) glass-fiber post customized with flowable composite resin; (G8) glass-fiber post cemented with light-cure composite resin; (G9) glass-fiber post cemented with self-adhesive resin cement. After the post insertion, all specimens were subjected to mechanical (250,000 cycles) and thermocycling (6000 cycles, 5 °C/55 °C) and immediate loading at 45 degrees in a universal testing machine until fracture. The data were analyzed by one-way ANOVA and multiple comparisons using the Fisher LSD Method (p < 0 05). Results: The mean failure loads (±SD) for the groups ranged from 100.7 ± 22.6 N to 221.9 ± 48.9 N. The G1 group (without endodontic posts) had a higher fracture strength than all experimental groups (p < 0.001). Conclusions: Within the limitations, the light- and dual-cure post technique did not present lower fracture resistance values as compared to the conventional glass-fiber post.

Effect of partial ferrule on fracture resistance of endodontically treated teeth: A meta-analysis of in-vitro studies.

The present meta-analysis aimed to answer the following research question: In endodontically treated teeth (ETT), what is the effect of partial ferrule (PF) on fracture resistance compared to complete ferrule (CF) and/or no ferrule (NF)? PubMed, Scopus, Web of Science, and Google Scholar were searched for relevant studies published until May 20, 2022. In vitro studies that compared the effect of partial ferrule with that of complete ferrule and/or no ferrule on fracture resistance of ETT were included. The studies were assessed for risk of bias, and a meta-analysis was performed. Seventeen in vitro studies comprising 807 teeth were included. Nine studies were at a high risk of bias and eight presented a moderate risk of bias. Overall, the results showed that CF was superior to PF in increasing fracture resistance (SMD= 0.93, CI95%= 0.57-1.29, P< 0.0001), with no change in the effect based on the type of teeth (P< 0.001). However, the subgroup analysis found that PF 2 mm buccal, lingual, and buccal and lingual ferrule were comparable to CF (P= 0.06). Additionally, the PF group showed significantly higher fracture resistance than the NF group (SMD= 2.02, CI95%= 1.54-2.49, P< 0.00001). Although CF design provided the highest fracture resistance to restored ETT, PF can still be a viable option for restoring ETT in cases where CF is not feasible.

A Literature Review of Minimally Invasive Endodontic Access Cavities - Past, Present and Future.

Minimally invasive endodontic access cavities have gained popularity in academic discussions for their clinical applications in recent years. Although some studies showed an improved fracture resistance of endodontically-treated teeth accessed with a minimally invasive access cavity design, the resulting effectiveness and efficiency of subsequent root canal treatment procedures may be impaired. Aspects that may be impaired are canal detection and negotiation, chemomechanical debridement of the root canal system, quality of the obturation. These are potentially complicated by the increased incidence of procedural mishaps and compromised aesthetic outcomes. In addition, the inherent flaws presented in the methodology of some in vitro studies and the lack of a universal classification system are also of concern. This literature review aims to present a comprehensive overview of the development of the minimally invasive endodontic access cavity and summarise the currently available from a clinical context.

Effect of photo core, LuxaCore, and core max II core building materials on fracture resistance of endodontically-treated teeth restored with fiber-reinforced composite posts and ParaPosts

Post and core treatment is commonly performed for endodontically treated teeth to replace the lost tooth structure and reinforce and protect the remaining dental tissue. This study aimed to compare the effect of three-core building materials on fracture resistance of endodontically-treated teeth restored with fiber-reinforced composite (FRC) posts and ParaPosts. This in vitro, experimental study evaluated 108 sound, single-rooted mandibular first premolars extracted for orthodontic purposes. The teeth were randomly divided into nine groups (n = 12) of control (no endodontic or restorative treatment), FRC + Photo Core (Group 2), FRC + LuxaCore (Group 3), FRC + Core Max II with bonding agent (Group 4), FRC + Core Max II without bonding agent (Group 5), ParaPost + Photo Core (Group 6), ParaPost + LuxaCore (Group 7), ParaPost + Core Max II with bonding agent (Group 8), and ParaPost + Core Max II without bonding agent (Group 9). The fracture resistance was measured by applying the load at 45° angle relative to the longitudinal axis of the tooth with a crosshead speed of 1 mm/min using a universal testing machine. Data were through descriptive statistics, Tukey's test, and one-way analysis of variance (α = 0.05). The mean fracture resistance was 454.0 ± 62.7, 410.8 ± 48.3, 365.1 ± 42.1, 423.7 ± 111.7, 392.4 ± 90.0, 292.3 ± 83.9, 242.3 ± 73.4, 278.2 ± 67.9, and 247.3 ± 49.6 N in Groups 1-9, respectively. Group 4 showed the highest fracture resistance, which was significantly higher than this study the value in all ParaPost and control groups (P < 0.05) but had no significant difference with the fracture resistance of other groups (P > 0.05). Fracture resistance is independent of the type of core building material used, and the tested products had no superiority over each other. The mean fracture resistance of FRC post groups were significantly higher than that of ParaPost groups. Furthermore, Core Max II + bonding agent yielded insignificantly higher fracture resistance than Core Max II without bonding agent.

Influence of Post Angulation between Coronal and Radicular Segment on the Fracture Resistance of Endodontically Treated Teeth.

The objectives of coronal restoration in the Endodontically Treated Teeth (ETT) include rehabilitation of aesthetics, function and prevention of coronal leakage. The long axis of root and the coronal segment in the maxillary anterior teeth varies according to the occlusal scheme. The restorative dentist is required to fabricate the post angulation in compatibility to contour of the adjacent teeth. To evaluate the influence of the angle between the long axes of core facial surface and the radicular segment of the post on fracture resistance of ETT. Total of 30 maxillary intact canines was root canal treated, sectioned 2 mm above the CEJ. The custom made nickel-chromium endodontic posts were fabricated using direct method. The samples were divided among three groups of 10 each. The angle between coronal segment and radicular segment of post in Group-I, Group-II, Group-III were 5°, 10° and 15° respectively. The teeth samples were cemented with full veneer metal crown and tested under universal testing machine. The static load at the angle of 130° was applied until the fracture to record the fracture strength. The obtained data was statistically analysed with ANOVA and Tukey post-hoc test. The Group-III showed the highest fracture strength with 666.15 N. The Group-II and Group-I recorded the mean fracture strength at 443.37 N and 276.74 N respectively. The endodontic post with higher angle between the long axis of facial surface and radicular segment long axis had the positive correlation to the fracture strength in ETT.

Effect of novel restorative materials and retention slots on fracture resistance of endodontically-treated teeth

Objectives. The aim of this study was to evaluate the fracture resistance of endodontically-treated teeth restored with nano-hybrid composite resin, bulk-fill flowable and short fibre-reinforced-composite in the absence/presence of retention slots. Materials and methods. One hundred and ten extracted non-carious human mandibular molars received endodontic treatment followed by mesio-occlusodistal (MOD) cavities with 3 ± 0.2 mm thicknesses of buccal and lingual walls. Teeth were divided into two main groups according to the retention slot preparation. The dove-tail retention slots were prepared on the middle of opposite buccal and lingual walls to create mechanical interlocking. Each group was further divided into four sub-groups according to restorative material types: control (no restoration), nano-hybrid composite resin (FiltekTM Z550), bulk-fill flowable (FiltekTM Bulk Fill) and short fibre-reinforced-composite (everX PosteriorTM). Restored teeth were subjected to compressive load at a strain rate of 1 mm/min. The data were statistically analysed using two-way ANOVA and Tukey’s test for multiple comparisons. Results. The fracture resistance was significantly affected by the presence of the retentive slots and restorative material (p < 0.05). Restored teeth with retentive slots significantly increased the fracture resistance compared with restored teeth without retentive slots (p < 0.05). Short fibre-reinforced-composite with retentive slot cavities had significantly higher fracture resistance values compared with the other test groups (p < 0.05). Conclusions. The preparation of retention slots may increase the fracture resistance of endodontically-treated teeth, especially, when restored with short fibre-reinforced composite. The use of short fibre-reinforced composite with retentive slots could be an alternative technique to prevent cuspal fracture on endodontically-treated teeth with MOD cavity.

Fracture resistance of endodontically-treated teeth submitted to bleaching treatment with hydrogen peroxide and titanium dioxide nanoparticles photoactivated by LED-laser

Objective: The aim of this study was evaluate the fracture resistance of endodontically-treated teeth after bleaching treatment using 15% hydrogen peroxide plus titanium dioxide nanoparticles (15HPTiO2) photoactivated by LED-laser, in comparison with protocols using 35% hydrogen peroxide (35HP), 37% carbamide peroxide (37CP) or sodium perborate (SP). Material and method: After endodontic treatment, fifty bovine extracted incisors were divided into five groups (n = 10): G1- without bleaching; G2- 35HP; G3- 37CP; G4- 15HPTiO2 photoactivated by LED-laser and G5- SP. In G2 and G4, the bleaching protocol was applied in 4 sessions, with a 7 day interval between each session. In G3 and G5, the materials were kept in the pulp chamber for 21 days, but replaced every 7 days. After 21 days, the crowns were subjected to compressive load at a cross head speed of 0.5 mm/min, applied at 135° to the long axis of the root using an eletromechanical testing machine, until fracture. The data were submitted to ANOVA and Tukey tests (p = 0.05). Result: The bleaching treatment in endodontically-treated teeth with 15HP plus TiO2 nanoparticles and photoactivated by LED-laser caused reduction of the fracture resistance similarly provided by 35HP, 37CP or SP (p&gt;0.05). All bleaching treatments reduced the fracture resistance compared to unbleached teeth (p&lt;0.05). Conclusion: All bleaching protocols reduced the fracture resistance of endodontically-treated teeth, but there were no differences between each other.

Erratum

In Operative Dentistry, 2010, 35–5, 530–537, Fracture Resistance of Endodontically-treated Teeth: Effect of Combination Bleaching and an Antioxidant, the first author was erroneously listed as Maryam Khoroushi, DDS, MS, professor, Department of Operative Dentistry &amp; Torabinejad Dental Research Center, School of Dentistry, Isfahan University of Medical Sciences, Isfahan, Iran. Dr Khoroushi's correct university title is associate professor. This update has been posted online.

Erratum

In Operative Dentistry, 2010, 35-5, 530–537, Fracture Resistance of Endodontically-treated Teeth: Effect of Combination Bleaching and an Antioxidant, the first author was erroneously listed as Maryam Khoroushi, DDS, MS, professor, Department of Operative Dentistry &amp; Torabinejad Dental Research Center, School of Dentistry, Isfahan University of Medical Sciences, Isfahan, Iran. Dr Khoroushi's correct university title is assistant professor. This update has been posted online.

Fracture Resistance of Endodontically-treated Teeth: Effect of Combination Bleaching and an Antioxidant

This in vitro study assessed the fracture resistance of endodontically-treated teeth undergoing combination bleaching with 38% and 9.5% hydrogen peroxide gels as in-office and at-home bleaching techniques, respectively. In addition, the effect of an antioxidizing agent, sodium ascorbate, was investigated. Sixty maxillary premolars were endodontically-treated, received a glass ionomer barrier as a mechanical seal and were embedded in acrylic resin up to the cemento-enamel junction. The specimens were divided into four groups (n = 15) as follows: G I: no bleaching, access cavity restored with resin composite (negative control); G II: bleached for three weeks daily using 9.5% hydrogen peroxide for two hours and three sessions of in-office bleaching using 38% hydrogen peroxide every seven days, then restored (positive control); G III: bleached similar to G II and restored after one week; G IV: bleached similar to G II, along with the use of an antioxidizing agent for 24 hours, then restored. In each in-office and at-home bleaching session, the whitening gels were applied to the buccal surface of the tooth and placed inside the pulp chamber (inside/outside bleaching technique). Finally, the specimens underwent fracture resistance testing; the data were analyzed using ANOVA and Scheffé's test (alpha = 0.05). Significant differences were observed among the study groups (p < 0.05). Groups I and II demonstrated the highest and lowest fracture resistance, respectively. The samples that were not bleached (Group I) and the 10% sodium ascorbate gel group (Group IV) demonstrated significantly higher fracture resistance than the positive control group (p < 0.05). No significant differences were found between Groups III and II (p > 0.05). Within the limitations of the current study, it can be concluded that the fracture resistance of endodontically-treated teeth decreases after combination bleaching. The use of sodium ascorbate can reverse decreased fracture resistance.

Fracture Resistance of Endodontically-treated Teeth Restored Using Three Root-reinforcement Methods

The aim of this in vitro study was to compare the fracture resistance of endodontically-treated anterior teeth with their roots reinforced using three different restorative methods. Forty sound maxillary human central incisors were randomly assigned to four groups (n=10). The crowns of the teeth were removed at a level 2 mm incisal to the cementoenamel junction (CEJ). After root canal therapy, flared canals were simulated in three groups. In the first, second, and third groups the flared canals were reinforced with resin composite (RCO) (Clearfil DC Core Automix), two Reforpins (REF), and a resin cement (RCE) (Panavia F 2.0), respectively. In the fourth (DEN) group flared canals were not created. The same size fiber reinforced composite (FRC) posts were cemented with resin cement (Panavia F 2.0) in all groups. After post cementation and restoration of the teeth crown with a core build-up composite (Clearfil Photo Core), the roots of the teeth were embedded in acrylic resin blocks up to 1 mm below the CEJ. The samples were loaded in an Instron testing machine with a crosshead speed of 0.5 mm/min at a 45 angle to the long axis of the tooth on the palatal surfaces until failure occurred. Data were analyzed using the Kruskal-Wallis, Mann-Whitney, and Chi-square tests (p=0.05). Significant differences were found between fracture resistance in all of the groups (P<0.05) with the exception being among the RCO and REF groups. The least mean value 230 (130) N and the highest mean value 830 (220) N were shown in the fracture resistance of the RCE and DEN groups, respectively. Reforpin can be used as an alternative to resin composite for internal reinforcement of weakened roots according to the results of this study. For reinforcement of flared canals, fiber posts along with Reforpin or resin composite proved to have higher fracture resistance than resin cement. Non flared canals had the highest fracture resistance.

Effect of a Ferrule and Increased Clinical Crown Length on the In Vitro Fracture Resistance of Premolars Restored Using Two Dowel-and-Core Systems

This study investigated the effect of a crown-lengthening ferrule on the fracture resistance of endodontically-treated teeth restored with two dowel-core systems. Thirty-two extracted mandibular first premolars were sectioned perpendicular to the long axis at a point 1.0 mm occlusal to the buccal cementoenamel junction. Following endodontic treatment, the teeth were randomly assigned to four groups: cast Ni-Cr alloy dowel-core with no ferrule (Group A1), cast Ni-Cr alloy dowel-core with 2.0 mm ferrule (Group A2), prefabricated carbon fiber-reinforced dowel-resin core with no ferrule (Group B1) and carbon fiber-reinforced dowel-resin core with 2.0 mm ferrule (Group B2). Each specimen was embedded in a self-cured acrylic resin block from 2.0 mm apical to the margins of a cast Ni-Cr alloy crown, then loaded at 150 degrees from the long axis in a universal testing machine at a crosshead speed of 1.0 mm/minute until fracture. The data were recorded and analyzed using ANOVA and Fisher's exact tests, with alpha = 0.05. Mean failure loads (kN) for the A1, A2, B1 and B2 Groups were: 1.46 (S.D. 0.45), 1.07 (0.21), 1.13 (0.30) and 1.02 (0.27). The teeth restored with cast Ni-Cr dowel-cores and 2.0 mm ferrules demonstrated significantly lower fracture strengths, p = 0.04. There were significant differences in the root fracture patterns between the two dowel systems, with the carbon fiber-reinforced dowel-resin core system, being the less severe p < 0.05. Crown lengthening with a 2.0 mm apical extended ferrule resulted in reduced fracture strengths for endodontically-treated teeth restored using two dowel-core systems and cast metal crowns. The carbon fiber-reinforced dowel-resin core system reduced the severity of the root fractures.