Fracture Resistance Of Teeth Research Articles

Investigation of the Effect of Bleaching on Discolored Teeth After Regenerative Treatment on Fracture Resistance of Teeth

Objective: This study aimed to evaluate the effect of bleaching discolored teeth after regenerative endodontic treatment on fracture resistance. Methods: Forty human maxillary incisors were selected for the study and were divided into four study groups (n=10). Group 1 was called the positive control group, and no treatment was applied. In Group 2; root canals were enlarged to size 6 peezo reamer bur to mimic an immature tooth. The disinfection protocol was performed according to the regenerative endodontic treatment protocol of the American Association of Endodontists. 3 mm thick mineral trioxide aggregate (MTA) was placed at the cementoenamel margin and restored with a temporary restorative material. The samples in group 3 were restored with glass ionomer and composite resin. In Group 4 bleaching was applied with 35% hydrogen peroxide bleaching agent to the samples before restoration with glass ionomer and composite resin. Then each group was applied to the cervical fracture resistance test with a universal testing machine. The fracture resistance values were recorded in Newtons (N), and the obtained data were analyzed statistically. Results: While the highest fracture strength was obtained in group 1 (1092 ±9.27N), the lowest fracture resistance was observed in group 2 (493.8 ±7.60N). The difference between all groups was statistically significant (p<0.05). Conclusion: 35% hydrogen peroxide bleaching agent application after regenerative endodontic treatment reduces fracture resistance of the tooth.

Fragment reattachment or direct restoration? An in vitro study.

The fracture resistance of teeth subjected to fragment reattachment may improve when the technique is performed using intermediate materials. The aim of this study was to evaluate the influence of different bonding materials, including pre-heated composite resin, on the fracture resistance of teeth subjected to the reattachment technique compared with a direct composite resin restoration. After simulating a tooth fracture, each specimen was reattached by using one of the following intermediate materials (n=15): G0, negative control (sound teeth); G1, Z100; G2, pre-heated Z100; G3, Filtek Z350 XT; G4, pre-heated Filtek Z350 XT; G5, Filtek Z350 XT Flow; and G6, RelyX Veneer. In G7, direct class IV restorations were performed using Filtek Z350 XT composite resin. The fracture resistance was evaluated using a universal testing machine under a compressive load of 1 mm/min. One-way analysis of variance (ANOVA) and the post hoc Tukey test (5%) were conducted. G0 showed the highest fracture resistance, and this was statistically different from the other experimental groups (p < .05) except for G2 and G4, in which the fragments were bonded using pre-heated resins. A statistically significant difference was found between groups G1 and G6 (one-way ANOVA, p=.04). For G1 and G2, a significant difference was found between bonding with and without pre-heating (p < .05). This difference was not observed in G3 and G4 (p > .05). No statistically significant difference was found between the reattached and directly restored groups (t-test, p=.53). The tooth reattachment technique using pre-heated composite resin showed fracture resistance values similar to those of the sound tooth group. No difference was found between the fragment reattachment and direct composite resin techniques.

Comparative evaluation of pericervical dentin preservation and fracture resistance of root canal-treated teeth with rotary endodontic file systems of different types of taper - An in vitro study.

The aim of this study was to evaluate and compare the pericervical dentin preservation and fracture resistance of root canal-treated teeth with rotary endodontic file systems of different types of taper. Thirty-two single-rooted human-extracted premolars were used. They were mounted in wax, and preoperative cone-beam computed tomography (CBCT) scans were taken with 11 × 8 Field of view (FOV). The evaluation of the pericervical dentin thickness was done at the cementoenamel junction level. After pre-CBCT, the 32 samples were divided into four groups (n = 8) - Group A: fixed tapered hand files, Group B: variable regressive tapered TruNatomy, Group C: progressive tapered ProTaper Gold, and Group D: fixed tapered HyFlex EDM. Following instrumentation, postoperative CBCT scans were taken to evaluate pericervical dentin thickness. Obturation was done and access cavity was restored with composite. Fracture strength was checked for all the samples using "universal testing machine" until fracture, and calculated in newtons (N). Student's t-test and ANOVA test, along with Tukey's post hoc analysis, were used for comparing mean values between the groups, and P < 0.05 was considered statistically significant. The results of this study showed that there is no statistically significant difference in preserving pericervical dentin with file system of different types of taper and fracture resistance between the groups. Within the limitations of the study, it was concluded that different types of file taper systems used for root canal preparation have no significant effect on the preservation of pericervical dentin and fracture resistance of teeth.

Assessment of minimally invasive file systems on resistance to fracture using traditional and contracted access cavity designs in the maxillary first and second molars.

The objective of the study was to evaluate the effect of access cavity design on fracture resistance of the extracted maxillary first and second molars prepared with three minimally invasive files. One hundred and twelve extracted human maxillary molars were selected for the study and divided randomly into three groups according to different minimally invasive files used (self-adjusting files [SAF], XP-endo Shaper [XP], and 4 V-Taper 2H [VT]) and one control group (CG). All experimental groups were subdivided into two subgroups, i.e., conservative access cavity (CAC) and traditional access cavity (TAC). All the canals in different experimental groups were enlarged up to apical size 30. The data were analyzed using the analysis of variance and Post hoc Tukey tests (P < 0.05). The highest mean fracture resistance of teeth with CAC was of the CG (1399.957), followed by teeth with CAC instrumented by SAF (1378.314) and XP-endo Shaper (1202.929). The least value was of the V-Taper file system (937.157). Furthermore, the highest mean fracture resistance value of teeth with TAC was of the CG (1143.171), followed by teeth with TAC instrumented by SAF (1150.607) and then XP-endo Shaper (998.150). The least value was of the V Taper file system (757.050). Conservative endodontic access (CAC) in the maxillary molars had shown significantly increased fracture resistance over TAC. SAF showed the maximum fracture resistance, while V-Taper files showed the least fracture resistance among the experimental groups compared.

Fracture Resistance of Molars With Simulated Strip Perforation Repaired With Different Calcium Silicate-Based Cements.

Background and aims A root perforation is a connection between the root canal system and the external supportive tissues. Strip perforation (SP), occurring within root canals in a strip, can worsen the prognosis of a treated tooth, reduce its mechanical resistance, and impair the tooth structure. One of the suggested methods to treat SP is to seal it with a bio-material such as calcium silicate cement. Therefore, this in vitro study aimed to assess the molar structure impairment due to SP, which requires studying the fracture resistance, and the ability of mineral trioxide aggregate (MTA), bioceramic, and calcium-enriched mixture (CEM) to repair this perforation. Materials and methods Seventy-five molars were instrumented to size #25 and taper 4%, irrigated with sodium hypochlorite and ethylenediaminetetraacetic acid (EDTA), dried, and then divided randomly into five groups (G1-G5): in G1, root canals were filled with gutta-percha and sealer (negative control sample), whereas the rest of the groups (G2-G5) had a manual simulated SP made with Gates Glidden drill at the mesial root of the extracted molar, and filled with gutta-percha and sealer up to their perforation area; in G2, SP was filled with gutta-percha and sealer (positive control sample); G3 used MTA to repair the SP; G4 used bioceramic putty; and G5 used CEM. Fracture resistance tests of the molars were conducted in the crown-apical direction using a universal testing machine. One-way ANOVA test and Bonferroni test were used to study the significance of the differences in the mean values of the tooth fracture resistance, where statistical significance was set at 0.05. Results The ANOVA test showed that there were statistically significant differences between the fracture resistance (in newtons) values among groups (p = 0.000). The Bonferroni test showed that G2 had a smaller fracture resistance mean than the other four study groups (656.53 N; p = 0.000), and that of G5 was smaller than G1, G3, and G4 (794.40 N, 1083.73 N, 1025.20 N, and 1034.20 N, respectively; p = 0.000 in each pairwise comparison). Conclusion SP reduced the fracture resistance of endodontically treated molars. SP restored using MTA and bioceramic putty was better than that treated with CEM and similar to molars without SP. Moreover, MTA and bioceramic putty enhanced the fracture resistance of endodontically treated teeth to levels similar to molars without SP.

Comparative Cone Beam Computed Tomographic Evaluation of Conventional and Conservative Endodontic Access Cavity Designs on Pericervical Dentin Thickness and Fracture Resistance of Teeth: An In-vitro Study

Introduction: The concept of ‘extension for prevention’ accelerates treatment processes but eliminates precious dentin at the pericervical area, resulting in biomechanically weakened tooth structure after endodontic treatment. Pericervical Dentin (PCD) is a new paradigm for endodontic success supports the idea that the amount of residual tooth structure is closely associated with long-term retention of the tooth and resistance to fracturing. Aim: To determine the impact of two endodontic access cavity designs and biomechanical preparation on the pericervical dentin thickness using 3D Cone Beam Computed Tomographic (CBCT) visualisation technique and fracture resistance of the maxillary anterior teeth under compressive load using universal testing machine. Materials and Methods: The in-vitro study was conducted in the Department of Conservative Dentistry and Endodontics at Karnavati School of Dentistry, Gandhinagar, Gujarat, India, from October 2020 to March 2021. Study was carried out on the 30 single rooted freshly extracted maxillary central incisors and were randomly divided into two groups of conventional and conservative access preparation groups (n=15). Group 1 was conventional group, samples were accessed using endo access bur #1. Group 2 was conservative group, samples were accessed using CK micro-endodontic bur under a dental operating microscope. Cleaning and shaping was done using 17% Ethylenediamine Tetraacetic Acid (EDTA) as lubricant and 4% Hyflex CM rotary file system. The CBCT scans were taken preoperatively, following access cavity preparation and postobturation to evaluate the amount of pericervical dentin loss in mesial, lingual, facial and distal surfaces of the teeth at the levels of 1 mm to 4 mm above and below Cementoenamel Junction (CEJ). The samples were then loaded to fracture in the Universal Testing Machine, and the data were analysed using Independent sample t-test using Statistical Package for Social Sciences (SPSS) software version 20.0. Results: In comparison to the group 2, group 1 led to an increase in substantial tooth structure loss in the pericervical region. Among all surfaces, pericervical dentin loss was more pronounced on the lingual surface in the group 1 than in the group 2 (p-value &lt;0.001). Higher fracture resistance was observed in group 2 (1136.75 N) compared to group 1 (687.22 N) under compressive load (p-value &lt;0.001). Conclusion: Incisal cavity design is a less invasive method of accessing maxillary central incisors that preserves pericervical dentin. Under compressive load, pericervical dentin conservation provided greater fracture resistance in the conservative group than in the conventional group.

Impact of access cavities on root canal preparation, restorative protocol quality, and fracture resistance of teeth.

The survival of endodontically treated teeth depends on the remaining tooth structure. The aim of this study was to evaluate the impact of different access cavities on root canal preparation, restorative protocol, and fracture resistance of endodontically treated teeth. Fifty-six mandibular molars were divided into control (n=8) and experimental (n=16) groups according to access cavity: Traditional, Conservative, and Truss; and redistributed (n=8) according to instrumentation protocols: Reciproc Blue and R-motion. After, teeth were scanned in micro-CT and then filled and redistributed according to composite resin restoration (n=8): Filtek One BulkFill and Filtek Z350. A new micro-CT scan was performed to analyze the restorative material. Then, samples were submitted to fracture resistance testing and the failure pattern was determined. Data were analyzed using paired T-test, ANOVA, Tukey, and chi-square tests (α=0.05). In Truss, R-Motion promoted less transportation in different thirds of root canals. Higher percentages of voids (5.05%) and filling material (11.7%) were observed in Truss. Fracture resistance values were higher for the control group, followed by Truss, Conservative, and Traditional. The predominant failure pattern was type-II. In Truss, reciprocating instruments with smaller taper showed less canal transportation. Also, Truss provided higher values of fracture resistance, although it presented a higher percentage of voids and remaining filling material. Thus, in Truss, reciprocating files with smaller taper showed less canal transportation, and these cavities provided higher values of fracture resistance, although it presented a higher percentage of voids and remaining filling material.

Effect of deep margin elevation on fracture resistance of premolars restored with ceramic onlay: In vitro comparative study.

This in vitro comparative study aimed to compare the influence of two levels of deep margin elevation (2 and 3 mm) with either bulk-fill flowable composite or short fiber-reinforced flowable composite on the fracture resistance of maxillary first premolars restored with ceramic onlays. Fifty sound-extracted maxillary first premolar teeth were selected to prepare mesio-occluso-distal cavities with standardized dimensions. The cervical margins were extended 2 mm below the cemento-enamel junction on both mesial and distal sides. These teeth were randomly divided into five groups: Group I: no box elevation (control group). Group II: 2 mm marginal elevation with bulk-fill flowable composite. Group III: 2 mm marginal elevation with short fiber-reinforced flowable composite. Group IV: 3 mm marginal elevation with bulk-fill flowable composite. Group V: 3 mm marginal elevation with short fiber-reinforced flowable composite. After cementation, all teeth were subjected to a fracture resistance test using the universal testing machine, and the mode of failure was analyzed using a digital microscope at 20x magnification. The result showed a non-significant difference in the fracture resistance between 2 and 3 mm marginal elevation (p>0.05) with respect to each restorative material used for deep margin elevation. However, the fracture resistance of teeth elevated with short fiber-reinforced flowable composite was significantly higher than those elevated with bulk-fill flowable composite at both levels 2 and 3 mm, p=0.041 and 0.038 respectively. The fracture resistance of premolars restored with a ceramic onlay was not influenced by the levels of deep margin elevation (2 or 3 mm). However, marginal elevation with short fiber-reinforced flowable composites provided higher fracture resistance than those elevated with bulk-fill flowable composites, and those without marginal elevation. Key words:Fracture Resistance, Short fiber reinforced flowable composite, Bulk-fill flowable composite, Ceramic onlay, Cervical margin elevation.

Comparison of fracture resistance of mandibular central incisors following the use of two different spreaders during lateral condensation obturation technique- An in vitro study

The lateral condensation is the most commonly practiced obturation technique during root canal treatment. In this method, the use of spreaders is instrumental in acheiving 3-D obturation. These spreaders can create an unnecessary stress during use, by means of wedging force that might lead to vertical root fracture, resulting in failure of root canal treatment. Sixty extracted mandibular central incisors were taken. All teeth were sectioned 2 mm coronal to CEJ and were wrapped in aluminium foil. The specimens were embedded in acrylic mould. Aluminium foil was scratched and the created space was filled with light body silicone impression material. Then, after working length determination, apical preparation was done with 40 no. K- file. Rest of the canal was prepared using step back technique. The samples were then randomly divided into 3 groups of 20 samples each. Group 1 No obturation (control group). Group 2 Obturation done using stainless steel finger spreaders. Group 3 Obturation done using nickel titanium finger spreaders. After the obturation, all samples were subjected to fracture using metal indenter on the universal testing machine. The load at which fracture occur was recorded. Data thus obtained was subjected to statistical analysis using ANOVA and TUKEY test. The mean fracture resistance of group 1 was highest followed by group 3 (NiTi spreader) and least in group 2 (SS spreader). NITI or SS spreaders can affect the fracture resistance of teeth during lateral condensation obturation technique.

Reinforcement of Endodontically Treated Teeth by Different Intraorifice Barrier Materials

Background: Fracture incidences are more common in teeth with endodontic therapy and hence endodontic therapy should aim toward the reinforcement of such teeth by placing various restorative materials. Aims: Comparative evaluation of different intraorifice barrier material on strengthening the fracture resistance of teeth requiring endodontic therapy. Methods: Sixty extracted human mandibular premolars with one root were divided into four groups (n = 15); Group 1- Light cured Glass ionomer cement, Group 2 - Nanohybrid composite (NHC), Group 3 - High copper amalgam, Group 4-Control. Decoronation of specimens was done to a standardized length of 14 mm and was instrumented up to International Organization for Standardization (ISO) #30 size master apical file. Gutta percha was used to carry out the obturation by the cold lateral compaction technique. With the exception of the control group, elimination of 3 mm obturation from the coronal portion was done and intraorifice barrier materials were placed. Universal Testing Machine was used for testing fracture resistance. Statistical Analysis: Analysis of variance was applied to analyze the data obtained and pairwise comparison was done by post hoc tukey's test (P &lt; 0.05). Results: Better resistance to fracture incidence was seen with NHCs. Control group presented the least values. Conclusion: On placement of intraorifice barrier materials in teeth with endodontic therapy, there was a reduction in fracture incidence.

Comparative Assessment of The Fracture Resistance of Teeth Instrumented by Two Different Nickel Titanium Rotary Systems

Aim: This study aimed to compare the fracture resistance exhibited by roots on instrumentation using two endodontic rotary systems: SANI S3 and EdgeEndo X7 rotary file systems. Materials and Methods: Sixty recently extracted human mandibular premolars comprising single root canals were selected in this study. All specimens were decoronated and mounted perpendicularly in self-cure acrylic resin blocks exposing 6 mm of the roots out of the acrylic resin blocks. The specimens were divided into two experimental groups, according to NiTi rotary systems used and one control group (n = 20). After instrumentation, the specimens of both experimental groups were then filled using master Gutta-percha cones size 35 (0.04 taper) and obturation was done using continuous wave compaction technique. The specimens were kept at 37 °C and 100% humidity for 2 weeks to allow complete setting of the sealer. Root fracture resistance was assessed using a universal testing machine (Instron) and the amount of load necessary for root fracture was recorded in Newtons (N). Statistics: Data were collected, tabulated and statistically analyzed using one-way ANOVA test and Tukey’s posthoc test. Results: Group C (control) exhibited the highest mean fracture force (357.13 ± 20.61) while group A (SANI S3) showed the lowest mean fracture force (192.60 ± 22.73). One-way ANOVA test showed statistically significant differences between tested groups. Regarding inter-group comparisons using Tukey’s test, there was a significant statistical difference between groups (A and B) and between groups (A and C). Furthermore, there was a statistically significant difference between groups (B and C). (P?0.05) Conclusion: 1-Root canal instrumentation with NiTi rotary files possessed a negative impact on roots and higher risks of root fractures compared to intact unprepared roots. 2-Design of NiTi files with improved cutting efficiency could diminish the risk of crack formation in root canal dentinal walls.

Comparison of the fracture resistance of the teeth prepared with ProTaper Universal, ProTaper Next, and ProTaper Gold rotary files.

Root canal preparation can lead to cracks on the roots by creating stresses on the root canal walls, which decreases the fracture resistance of the tooth. The present study compared the fracture resistance of the teeth prepared by the ProTaper Universal (PTU), ProTaper Next (PTN), and ProTaper Gold (PTG) rotary file systems. Fifty-six single-canal premolar teeth were sectioned 14 mm from the root apex. The roots were standardized based on the buccolingual and mesiodistal diameter and randomly assigned to three experimental (n = 14) and one control group (n = 14). The teeth in three experimental groups were instrumented with PTU, PTN, and PTG rotary files. The roots in the control group were not instrumented. A vertical force was applied to each root in a universal testing machine until the root fractured. The data were statistically analyzed by one-way analysis of variance. There was no significant difference in the fracture resistance of the teeth between the control, PTU, PTN, and PTG groups (p = .115). Root canal preparation with ProTaper files manufactured with conventional NiTi (PTU) and heat-treated alloys (PTN and PTG) did not affect the fracture resistance of teeth.

Comparing techniques for removal of separated endodontic instruments

Purpose: The goal of this study is to look into several approaches to approaching damaged instruments in the root canal, as well as to show possible outcomes in terms of dentin thickness, fracture resistance, technique success, and clinical time. Methodology: PubMed, Cochrane, Lilacs, Web of Science, Scopus, grey literature, and manual searches were used to conduct the bibliographic research. The titles and abstracts of 506 papers were examined using the inclusion and exclusion criteria. Sixty items were chosen and read in their entirety. This systematic review includes fourteen papers. Results: The ultrasonic approach was the most extensively researched and yielded positive results in general. The more apically positioned the tool is, the more difficult it is to remove it, the more dentin is removed, and the poorer the tooth's fracture resistance. When removal is not possible, the bypass technique (bypassing) can be employed, and the GentleWave System approach can be used on weakened teeth or with little dental fragments. Conclusion: The data from laboratory investigations showing the curvature and root third in which instrument fractures originate is related to fracture resistance and success is presented in this comprehensive review.

Fracture Resistance of Teeth Restored by Layered and Nonlayered Composite Resin

Fracture Resistance of Teeth Restored by Layered and Nonlayered Composite Resin

A Comparative Evaluation of Fracture Resistance of Teeth Obturated with a Novel Sealer: Chitra CPC with Endosequence BC Sealer, MTA Fillapex and AH Plus

Background: Bonding of sealer to root canal walls is likely to increase the integrity of the sealer-dentin interface during mechanical stresses, thus increasing resistance to fracture. Chitra-CPC sealer is an indigenously manufactured bioceramic material and has been used as bone graft and perforation repair material. When used as a sealer, it has good potential to reinforce the root strength in addition to excellent biocompatibility.&#x0D; Aim: To compare the fracture resistance of teeth obturated with novel Calcium phosphate cement-based sealer viz. Chitra CPC with Endosequence BC sealer, MTA Fillapex and AH Plus&#x0D; Methods and Material: The study was carried out in 100 single rooted extracted, decoronated mandibular premolars of length 11 mm. The teeth were randomly divided into 4 groups (n = 20 for each group). Other than Group 1A and group1B, all other groups were restored with various endodontic sealers and obturated with Gutta Percha. In group1A, the teeth were left unprepared and unfilled (negative control), in group 1B, the teeth were left unobturated (positive control) In group 2, Epoxy resin based sealer (AHPlus ) ;In group 3, mineral trioxide aggregate–based sealer (MTAFill apex); In group 4, Calcium phosphate cement based sealer (Chitra-CPC);in group 5,Bioceramic based sealer(Endosequence BC ) were used. After 2 weeks all specimens were tested for fracture resistance using Universal testing machine at a crosshead speed of 1.0 mm/min until the root fractured. The force required to fracture each specimen was recorded, and the data was analysed statistically.&#x0D; Results: The fracture resistance values of Chitra –CPC and Endosequence BC sealer were significantly higher than that of positive control and comparable to negative control.&#x0D; Conclusions: In contrast to MTA Fill apex and AH Plus, Chitra –CPC and Endosequence BC sealer increased the fracture resistance of teeth.

Effect of different apical plug thickness of calcium silicate cements on fracture resistance of simulated immature teeth

Aim and Objectives: Treatment goal of traumatized immature teeth is to provide a restoration that reinforces the tooth structure to improve function and esthetics. The present study was conducted to compare and evaluate the effect of different apical plug thickness of calcium silicate cements on fracture resistance of simulated immature teeth.&#x0D; Materials and Method: Eighty single rooted human teeth were sectioned and divided into eight groups (n=10). In Group I (positive control) no instrumentation was done. In the remaining seventy teeth endodontic access preparation was done and the root canals were instrumented with Peeso reamers. Group 2 (negative control), was filled with calcium hydroxide. In group 3, 4 5; MTA Plus was inserted into root canals to create 3-mm and 6-mm apical plugs and full obturation, respectively. Similarly in Group 6, 7, 8; Biodentine was inserted to create a 3-mm and 6-mm apical plug and full obturation, respectively. The remainder section of the canals in Group 3, 4 6, 7 were obturated with conventional gutta-percha and AH Plus sealer. The fracture testing of each specimen was performed using a Universal Testing Machine and force was recorded in newton (N). The values obtained was statistically analyzed using one way Anova and Post Hoc Tukeys tests.&#x0D; Results: The maximum fracture resistance was seen in Group 3, which showed significantly greater values than Group 1, 2, 5, 6, 7&amp;8 (p&lt;0.05). No significant differences were found between the Group 3 and 4 and between Group 6 and 7 (P &gt; .05).&#x0D; Conclusion: Up to 6mm thickness of apical plug can be created with MTA Plus and Biodentine without deteriorating the fracture resistance of tooth complex.

The potential of high molecular chitosan nanohydroxyapatite as an irrigant in improving fracture resistance after root canal treatment (In Vitro)

ABSTRACT Teeth after root canal treatment are at a higher risk of fracture than vital teeth. After root canaltreatment, the causes of tooth fracture are multifactorial, both iatrogenic and non iatrogenic. One of them isirrigants, although very useful for disinfection. Irrigants are known to change the chemical components andstructure of the root canal surface dentin by modifying the proportion of calcium and phosphate minerals. Thisresearch is an experimental laboratory study with a post-test-only group research design to analyze the effect ofirrigating solutions of nanohydroxyapatite, high molecular chitosan, NaOCl, and EDTA with their appropriatecombination for the test group on the fracture resistance of teeth after root canal treatment. Root canal treatment wasperformed on 24 mandibular premolars, with the group I; irrigating solution of nanohydroxyapatite, group II;irrigation of nanohydroxyapatite solution with the addition of 0.2% chitosan, group III; irrigation with 2.5% NaOClsolution and 0.2% chitosan solution, group IV; irrigation solution of 2.5% NaOCl and 17% EDTA. ANOVA testshowed a significant difference in fracture resistance (p0.05) between each group. The highest average fractureresistance was seen in group II, namely the irrigation group using a solution of nanohydroxyapatite with theaddition of 0.2% chitosan, which was 363.644 ± 10,896 N. fracture after root canal treatment.KEYWORDS: nanohydroxyapatite, irrigation solution, fracture resistance

Fracture resistance of endodontically treated maxillary incisors restored with single or bundled glass fiber-reinforced composite resin posts.

BackgroundTo compare the fracture resistance of endodontically treated maxillary incisors restored with single versus bundled glass fiber-reinforced composite resin posts (FRC). Material and MethodsTwenty-four maxillary incisors underwent root canal preparation (1.5-mm-diameter post spaces after canal obturation). Teeth were randomly divided into two groups (n = 12). Two different FRC groups were used for the intracanal post treatment. Single FRC (Rebilda Post system, 1.5 mm diameter) and bundled FRC (Rebilda Post GT, 12 fiber bundles, 1.4 mm diameter) were bonded to the prepared canals using dual-cure resin-based luting cement. Specimens were kept in humid at 37°C for one day. The fracture resistance testing was performed using universal testing machine by applying a compressive static load at a 135° angel to the axis of the teeth. The failure type after fracture was examined by visual inspection. ResultsThe fracture resistance of teeth with single FRC (Rebilda Post) and bundled FRC (Rebilda Post GT) were 787 ± 156 and 850 ± 166 Newton, respectively. There was no statistical significant difference between the two groups. Root fracture was the major failure type in both groups. ConclusionsThe fracture resistance of endodontically treated maxillary incisors with bundled FRC (Rebilda Post GT) did not differ from incisors with single FRC (Rebilda Post). Key words:Endodontically-treated teeth, fracture resistance, glass fiber post, intracanal post.

Fracture Resistance of Teeth Restored with Newer Methacrylate-Based Dental Composite Materials: An In Vitro Study

Introduction: Composite have evolved significantly due to the increase in the demand for a more esthetic and conservative approach in dentistry. Modifications have been made on the filler particle size and loading, followed by alterations in the resin matrix substance. Methacrylate-based composite with the addition of nanoparticles to the filler has been introduced in the market, providing improved esthetics and lower polymerization shrinkage. The present study was done to compare the fracture resistance of teeth restored using two newer methacrylate-based composite materials, along with the flexural strength of the composites. Methods: Sixty mandibular premolars were divided into two control groups of 10 teeth each and two experimental groups of 20 teeth. Group I − intact teeth with no preparations (n = 10), Group II − prepared but unrestored teeth (n = 10), Group III − teeth prepared and restored with a stackable nanohybrid methacrylate-based composite material (IPS Empress DirectTM), and Group IV − teeth prepared and restored with a packable submicron methacrylate-based composite material (Brilliant EverglowTM), respectively. The teeth were embedded in resin-filled PVC rings, and a compressive loading test was carried out for all groups at a cross-head speed of 0.5 mm/min. The flexural strengths of the two composite materials were also analyzed using three-point bending test using Universal Testing Machine. The statistical significance (P < 0.05) of the differences between the experimental groups was analyzed by ANOVA and Tukey post hoc test. Results: The mean fracture resistance was highest in Group IV (1877.37 ± 494.79) followed by Group III (1763.69 ± 392.51), Group I (1607.08 ± 283.48), and Group II having the least (1442.08 ± 373.66). The mean fracture resistance overall differed significantly between the four groups (P = 0.048). Tukey test showed fracture resistance differed significantly between Group II and Group IV (P = 0.042) and no significance among other groups. Conclusion: Fracture resistance was highest in the group restored with the packable submicron hybrid composite material. The packable submicron methacrylate-based composite material also showed higher flexural strength than stackable nanohybrid composite material.

FARKLI NİKEL-TİTANYUM DÖNER ALET SİSTEMLERİNİN FARKLI KİNEMATİKLERDE KULLANIMININ ENDODONTİK TEDAVİ GÖRMÜŞ KÖKLERİN KIRILMA DİRENCİNE OLAN ETKİSİNİN İNCELENMESİ

Amaç. Çalışmamızın amacı ProTaper Universal (PTU), ProTaper Gold (PTG), Twisted File Adaptive (TFA) ve WaveOne (WO) NiTi Döner Alet sistemlerini farklı kinematiklerde kullanarak yapılan kök kanal şekillendirilmesinin dişlerin kırılma dirençlerine olan etkisini araştırmaktır. Gereç ve Yöntem. Tek köklü ve tek kanallı 160 adet alt kesici dişler seçildi. Dişler mine-sement birleşim yerinden ayrıldıktan sonra örnekler 8 gruba bölündü (n=20). Grup 1 hariç diğer gruplarda 10 K-tipi eğe kök kanallarında ilerletildi ve bu boydan 1 mm çıkartılarak çalışma uzunluğu belirlendi. 15 K-tipi eğe ile kayma yolu oluşturuldu. Kontrol grubunda köklere hiçbir şekillendirme işlemi yapılmadı. WO eğeleri sadece resiprokasyon hareketinde kullanıldı. Diğer eğeler ise hem üretici talimatlarındaki hareketle hem de resiprokasyon hareketiyle kullanıldılar. Örneklere periodontal ligamentleri taklit etmesi amacıyla elastomerik ölçü maddesi kullanıldı. Daha sonra Universal test cihazında 1mm/ dakika hızla örneklere kuvvet uygulandı. Örneklerde kırılmaya neden olan maksimum kuvvet değerleri ( F-Max) belirlendi ve sonuçlar tek yönlü varyans analizi (ANOVA) ve post-hoc LSD testleri kullanılarak istatistiksel değerlendirilmeye tabi tutuldu. (P<0.05) Bulgular. Kontrol grubu en yüksek kırılma direncine sahipti ve PTU, PTU resiprokasyon ve PTG ve PTG resiprokasyon sistemleriyle arasında istatistiksel açıdan anlamlı fark vardı. (P<0.05). TFA, TFA resiprokasyon ve WO grupları ile kontrol grubu arasında köklerin kırılmaya karşı dirençleri açısından istatistiksel olarak anlamlı fark yoktu (P>0.05). Sonuç. Çalışmamızda rotasyon veya resiprokasyon hareketiyle kök kanalları genişletilmesinin dişlerin kırılma direncinde bir fark yaratmadığı görülmüştür fakat PTU ve PTG gruplarının dişlerin kırılma dirençlerini azalttığı sonucuna varılmıştır. Anahtar Kelimeler: ProTaper, Adaptive hareket, Rotasyon, Resiprokasyon Evaluation of the Effect of Different Nickel-Titanium Systems by Using Different Kinematics on the Fracture Resistance of Endodontically Treated Roots ABSTRACT Aim. The aim of our study is to investigate the effect of the preparation on the fracture resistance of teeth by using ProTaper Universal (PTU), ProTaper Gold (PTG), Twisted File Adaptive (TFA) and WaveOne (WO) NiTi rotary instrument systems in different kinematics. Material and methods. 160 mandibular incisor teeth with single root and single canal were chosen. After the teeth were separated from the cementoenamel junction, the roots were divided into eight groups (n=20). All groups except for group 1, the working length of the root canals were determined by inserting a size 10 K-type file into the root canal terminus and subtracting 1 mm from this measurement. A glide path was done via a size 15 K-type file. In the control group, the root canals were not prepared. WO files were used only in the reciprocating motion. Other files were used both with the movement in the manufacturer's instructions and with the reciprocating movement. The periodontal ligament was simulated by using elastomeric impression material. Vertical loading was carried out with a universal testing machine at 1 mm/min crosshead speed. The maximum force at fracture (F-max) was recorded for each root and the data were analyzed statistically by one way analysis of variance (ANOVA) and post-hoc LSD tests (P<0.05). Results. The control group presented the highest fracture resistance and differed significantly from PTU, PTU reciprocation, PTG and PTG reciprocation groups (P<0.05). There were no significant differences in the fracture resistance between control group, and TFA, TFA reciprocation and WO groups (P>0.05). Conclusion. In our study, it was observed that the root canal preparation did not make a difference in the fracture resistance of the teeth by rotation or reciprocation movement, but it was concluded that PTU and PTG groups reduced the fracture resistance of the teeth. Key Words: ProTaper, Adaptive motion, Rotation, Reciprocation