Effects of root canal sealers on vertical root fracture resistance of endodontically treated teeth

Upper First and Second Molar Pulp Chamber Endodontic Anatomy Evaluation According to a Recent Classification: A Cone Beam Computed Tomography Study

(1) The possibility of knowing information about the anatomy in advance, in particular the arrangement of the endodontic system, is crucial for successful treatment and for avoiding complications during endodontic therapy; the aim was to find a correlation between a minimally invasive and less stressful endodontic access on Ni-Ti rotary instruments, but which allows correct vision and identification of anatomical reference points, simplifying the typologies based on the shape of the pulp chamber in coronal three-dimensional exam views. (2) Based on the inclusion criteria, 104 maxillary molars (52 maxillary first molars and 52 maxillary second molars) were included in the study after 26 Cone Beam Computed Tomography (CBCT) acquisitions (from 15 males and 11 females). And linear measurements were taken with the CBCT-dedicated software for subsequent analysis. (3) The results of the present study show data similar to those already published about this topic. Pawar and Singh's simplified classification actually seems to offer a schematic way of classification that includes almost all of the cases that have been analyzed. (4) The use of a diagnostic examination with a wide Field of View (FOV) and low radiation dose represents an exam capable of obtaining a lot of clinical information for endodontic treatment. Nevertheless, the endodontic anatomy of the upper second molar represents a major challenge for the clinician due to its complexity both in canal shape and in ramification.

An In-Vitro Analysis of Root Fracture Strength Using Single File Systems

Aim Root canal obturation during endodontic therapy supports the root canal space and helps the extra tooth structure resist fracture. Some believe endodontic-treated teeth are more likely to break than natural teeth. The most common causes of tooth decay are endodontic treatment's extensive tooth structure loss and coronal and radicular dentin drying. Materials and methods Two hundred removed human permanent mandibular first molars were allowed to be stored in isotonic saline solution for a maximum of 72 hours. The collection, storing, sterilizing, and handling of the samples were done per the Occupational Safety and Health Administration (OSHA) and Centers for Disease Control and Prevention (CDC) guidelines. Out of a total of 200 newly removed mandibular first molars, 120 teeth were finally gathered, sterilized, and kept in 1% thymol in normal saline at 30 degrees Celsius. The access cavity was prepared, and the pulp chamber was cleaned and debrided using an ultrasonic scaler tip while being irrigated with regular saline. A digital radiograph was taken after a 6# K file was placed to the working length in the mesiobuccal canal. Based on their weights, the samples were dispersed equally across the six groups (n=20). They looked inside them to ensure that the root morphology was normal and that the canal was open and free of any abnormalities, damage, or fillings. They looked at the curvature of the mesial root and chose samples with a curvature of 20-35 degrees. The mesial roots were dissected, labeled, and put in a different location. Results Overall, the experimental group's incidence of buccolingual fractures was 55%, making it the most prevalent fracture type. The mesiodistal type of fracture had a 35% incidence rate, which was the second most prevalent. We found that comminuted and transverse fractures occurred in only 15% and 5% of patients, respectively, of all fractures. Both the test and the control groups had a disproportionately high number of buccolingual fractures. When comparing the root fracture loads of the two experimental groups, there was no significant difference (p>0.05) Conclusion Within this study's restrictions and standardization techniques, it can be concluded that the single file system-prepared roots' resistance to fracture was comparable to that of the control group. It is recommended to conduct additional research on these single file systems using different metrics and to assess them in a clinical setting.

Rapid Apical Healing with Simple Obturation Technique in Response to a Calcium Silicate-Based Filling Material

Background

Root canal sealers with high alkaline (pH more than 11) and bioactive properties (release ions) are more effective for healing the apical area and preventing reinfection in root canals. Pure calcium silicate-based bioceramic premixed injectable sealers lead to change the obturation technique because it depends on maximizing amount of sealer and single cone gutta-percha as a carrier. This retrospective clinical study aimed at demonstrating the effect of single cone gutta-percha with a calcium silicate-based filling, used to fill the root canal in a single visit, on the apical healing with different lesion size.

Materials and Methods

195 patients needing root canal treatment were treated at the Al-Jazaer private clinic in southern Iraq. Cases were obtained during the 2017–2021 period (retrospective study). All patients were treated with a simple hydraulic condensation technique that used calcium silicate-based filling materials as the sealer with single cone gutta-percha as the carrier, with a minimum follow-up period of approximately one year. Both treatment- and patient-related factors were evaluated. The clinical outcomes depended on classification with respect to complete (success) or incomplete (failure) healing. Statistical analysis was performed using a chi-square test to compare different related factors.

Results

Radiographs for 195 patients were examined, and the average follow-up time was 20.44 months. The complete healing success rate was 164 (84.1%), and 31(15.9%) patients were not healed. The highly significant success rate was 88.7% for the initial treatment compared with 63.9% for retreatment. Small and medium lesions (<5 mm diameter) had a significant success rate compared to large lesions (>5 mm diameter). Sealer extrusion was found in 68.7% of cases, but it did not have any significant effect on the treatment result.

Conclusions

The bioceramic calcium silicate-based filling sealer used with single-cone gutta-percha led to increased success of apical healing with a simple hydraulic condensation technique without multiple visit treatments and premedication material.

What Are the Chances of Resilon to Dominate the Market Filling Materials for Endodontics?

This paper is a literature review with additional virtual analyses of the authors’ own experimental research results. Knowledge from various areas was synergistically combined, appropriately for concurrent engineering, presenting several possible methodological approaches used in research, optimizing the selection of engineering materials and the conditions of their application with particular application in endodontics. Particular attention was paid to the theoretical aspects of filling material strengths, weaknesses, opportunities, and threats SWOT analysis. Attention was paid to the original concepts of Sustainable Dentistry Development in conjunction with Dentistry 4.0, which includes endodontics as an important element. The dentists’ actions, among others, in conservative dentistry, along with endodontics, requires close cooperation with engineers and the enginering sciences. Methods of root canal preparation were described, together with selected tools, including those made of nitinol. Principles concerning the process of cleaning and shaping the pulp complex are presented. The importance of obturation methods, including the Thermo-Hydraulic-Condensation THC technique, and the selection of filling materials with the necessary sealants for the success of endodontic treatment are discussed. The experimental studies were carried out in vitro on human teeth removed for medical reasons, except for caries, for which two groups of 16 teeth were separated. After the root canal was prepared, it was filled with studs and pellets of a filling material based on polyester materials, which has gained the common trade name of resilon or, less frequently, RealSeal (SybronEndo) with an epiphany sealant. The teeth for the first group were obturated by cold lateral condensation. In the second case the obturation was performed using the Thermo-Hydraulic-Condensation technique using System B and Obtura III. The experimental leakage testing was done using a scanning electron microscope SEM and a light stereoscopic microscope LSM, as typical research tools used in materialography. The research results, in a confrontation with the data taken from the literature studies, do not indicate the domination of resilon in endodontics.

Vertical root fracture resistance and dentinal crack formation of root canal-treated teeth instrumented with different nickel-titanium rotary systems: an in-vitro study

To compare the vertical root fracture (VRF) resistance of root canal-treated teeth instrumented with four different nickel-titanium (NiTi) rotary file systems and examine the dentinal crack pattern and direction using a new classification. Eighty mature mandibular premolars were selected and decoronated, leaving 13 mm of the root. The root samples were mounted in acrylic resin and divided randomly into five groups of different NiTi file systems: Group 1-control, Group 2-T-Pro, Group 3-HyFlex CM, Group 4-TG6 and lastly Group 5-ZenFlex. Samples in Group 2 and Group 3 were instrumented up to size 25/0.04, whereas Group 4 and Group 5 were instrumented up to size 25/0.06. Obturation was performed with AH Plus sealer and gutta-percha using single cone technique. Subsequently, all samples were subjected to occlusal compressive force until they were fractured. The force (N) needed to cause root fracture was recorded. The crack patterns and directions were also inspected under magnification and classified using a new and simple classification. The highest (VRF) resistance was noted in the control group (453.15 ± 92.23 N), followed by T-Pro (387.43 ± 76.81 N), HyFlex CM (381.88 ± 52.73 N), ZenFlex (369.15 ± 89.41 N) and finally TG6 (346.05 ± 72.08 N), but there was no significant difference between T-Pro and HyFlex (P = 0.438). A significantly higher prevalence (P = 0.001) of Type 1 crack pattern was observed, especially in samples instrumented with TG6. Majority of the cracks ran buccolingually except in some samples instrumented with ZenFlex (P = 0.898). Smaller file taper increased the VRF resistance of root canal-treated teeth. Majority of the dentinal crack exhibited Type 1 pattern and ran buccolingually.

The effect of diabetes on Fracture Resistance of Teeth: An in vitro study

The root fracture resistance (RFR) of premolars extracted from diabetic patients and the effect of biomaterials: white mineral trioxide aggregate (WMTA) and WMTA+Na₂ HPO₄ as an additive, on enhancing RFR were evaluated. Diabetic and non-diabetic teeth were divided into 4 subgroups (n = 5): root canals were obturated with WMTA, WMTA+Na₂ HPO₄ , gutta-percha and one unfilled (control). A plunger (1 mm diameter) applied a downward compressive load with crosshead speed of 1 mm min^-1 on the specimens mounted on resin blocks, and the ultimate force to fracture was measured. The mean RFR values of diabetic specimens were significantly lower. The lowest and highest means of RFR were recorded in the control and WMTA, in normal group and the control and WMTA+Na₂ HPO₄ in the diabetic group, respectively. The RFR in diabetic patients was significantly lower, indicating their higher susceptibility to fracture under vertical forces. The use of WMTA (with or without Na₂ HPO₄ ) for obturation enhances the RFR.

The "Butterfly Effect" and Its Correlation to the Direction of the Fracture Line in Root Dentin

INTRODUCTION

The butterfly effect is an optical phenomenon and is related to the presence of sclerotic dentin in the roots. The unique pattern of sclerotic dentin formation produces a characteristic butterfly shape in transverse sections of the roots. The objective of this study was to evaluate the direction of the fracture line in roots that exhibit the butterfly effect.

METHODS

Thirty single-rooted premolars with oval-shaped roots were decoronated and embedded in acrylic blocks and subjected to vertical force under a universal testing machine (HPBSD; Tec-Sol India, Chennai, India). Fractured roots were examined under a stereomicroscope (Model no. 080772; Lawrence and Mayo, Mumbai, India) at ×10 magnification to determine the location and direction of the fracture line. To evaluate the correlation between the direction of sclerotic dentin and the direction of the fracture line, teeth were sectioned and observed under a stereomicroscope at ×20 and ×40 magnification. The correlation was analyzed using the Fisher exact test (P < .05 for the coronal and apical thirds and P > .05 for the middle third).

RESULTS

Sclerotic dentin was observed more in the apical area and less in the coronal third of the root. The correlation between the direction of sclerotic dentin and the direction of the fracture line was statistically significant in the coronal and apical thirds of the root.

CONCLUSIONS

The vertical root fracture that runs buccolingually is correlated to the harder sclerotic dentin present in the mesiodistal direction.

Fracture Resistance of Titanium, Chrome-Cobalt, and Gold Alloy as Post and Core Materials: A Comparative Evaluation

Aim:

This study aimed to comparatively evaluate the fracture resistance of different metallic post and core materials.

Materials and Methods:

Twenty-four maxillary–central incisors were selected, standardized, and segregated into three groups (GP I–III) (n = 8) based on the type of alloy used for post and core preparation. GP I (gold alloy [Au]), GP II (chrome–cobalt alloy [Co–Cr]), and GP III (titanium alloy [Ti]) were comparatively evaluated for use as post and core materials. The teeth were endodontically treated and tooth preparation for post core was done.Metal post and cores were fabricated using indirect wax pattern and luted. Teeth were mounted on resin bases, fracture testing was done, and type of fractures were analyzed.

Results:

Mesiodistal type of fracture was the most common among experimental groups with a percentage incidence of 54.20%. The comminuted type of fracture was the next most common with a percentage incidence of 29.2%. The incidence of buccolingual, transverse, and other type of fracture was not common and had a percentage incidence of 29.2%, 4.2%, 8.3% and 4.2% respectively. Group II had the highest fracture resistance with a mean value of 742.89N. Group III and Group I had mean values of 482.33 and 361.1123N. Statistically significant difference between experimental groups (I and II) and (II and III) was observed in load values of root fracture (P < 0.05).

Conclusion:

On the basis of the protocols used and limitations of this study, among metallic post and core materials tested, GP II had the highest fracture resistance values. Further evaluation of these different post and core systems, new alloy formulations designed specifically for use as post and core materials, and assessment in a clinical setting is recommended.

Fracture Resistance of Roots Filled With Bio-Ceramic and Epoxy Resin-Based Sealers: In Vitro Study

Objective

This study aimed to assess the resistance of roots to fracture after being root canal filled with two types of endodontic sealers; bio-ceramic based sealer (TotalFill) and epoxy-resin based sealer (AH Plus).

Methods

Fifty-nine single canal mandibular premolars were instrumented. Group I (n=14, negative control): root canals were left without instrumentation and unfilled, group II (n=15, positive control): root canals were instrumented only and left unfilled, group III and IV (n=15 each): root canals were instrumented and filled with either gutta-percha/TotalFill or gutta-percha/AH Plus, respectively. The resistance of the roots to fracture was measured with a universal testing machine "Instron Corp" through recording the maximum force in Newton (N) needed to fracture each root. To analyze the data Kruskal-Wallis test was utilized, followed by Dunn's Bonferroni post hoc test for multiple comparisons. The level of significance was set at 0.05 (P≤0.05).

Results

TotalFill group showed slightly better fracture resistance (734.62 N) than AH Plus group (728.29 N). However, no statistical significant difference was found between the two groups (P>0.05). The greatest mean fracture force was shown in the negative control group (913.915 N) with statistical significant difference between the other three groups (P<0.05).

Conclusion

Gutta-percha/TotalFill and gutta-percha/AH Plus did not reinforce the root canal treated teeth.

Effect of Incisal Porcelain Veneering Thickness on the Fracture Resistance of CAD/CAM Zirconia All-Ceramic Anterior Crowns

Statement of Problem. In some clinical situations, the vertical length of either a prepared tooth or an implant abutment is short, while the occlusal clearance to be restored by a porcelain crown is large. Incisal thickness of the veneering porcelain should be considered to prevent mechanical failure of the crown. Purpose. The aim of this study is to evaluate the effect of two different incisal veneering porcelain thickness on the fracture resistance of the anterior all-ceramic CAD/CAM zirconia crown system as compared with the conventionally used metal ceramic crown system. Method. CAD/CAM zirconia all-ceramic and metal ceramic crowns were fabricated on the prepared dies with standardized dimensions and designs using standardized methods according to the manufacturer’s instructions. All crowns were then adhesively luted with resin-based cement (Multilink cement system), subjected to thermal cycling and cyclic loading, and were loaded until fracture using the universal testing machine to indicate the fracture resistance for each crown material in each veneering thickness. Results. Statistical analysis was carried out, and the results showed that the fracture resistance of the nickel-chromium metal ceramic group was significantly higher than that of the CAD/CAM zirconia all-ceramic group. Also, the fracture resistance of crowns with 1.5 mm incisal veneering thickness was significantly higher than those with 3 mm incisal veneering thickness in both groups. Furthermore, there was no significant difference in the fracture mode of the two groups where 50% of the total specimens demonstrated Mode II (veneer chipping), while 35% demonstrated Mode I (visible crack) and only 15% demonstrated Mode III (bulk fracture). Conclusion. High failure load values were demonstrated by the specimens in this study, which suggest sufficient strength of both incisal veneering thickness in both crown systems to withstand clinical applications; however, the fracture patterns still underline the requirement of a core design that support a consistent thickness of the veneering ceramic, and it is recommended to conduct long-term prospective clinical studies to confirm findings reported in the present study.

Root Reinforcement after Obturation with Calcium Silicate-based Sealer and Modified Gutta-percha Cone

INTRODUCTION

A root canal obturated with a calcium silicate-based sealer (bioceramic sealer [BCS]) and a modified gutta-percha cone (bioceramic cone [BCC]) might improve the fracture resistance of the root. The objective of this study was to evaluate root reinforcement of a bioceramic cone/sealer (TotalFill; FKG Dentaire SA, La Chaux-de-Fonds, Switzerland) by investigating the fracture resistance, push-out bond strength, sealer penetration, and modulus of elasticity (MOE) in comparison with gutta-percha/AH Plus (Dentsply Maillefer, Tulsa, OK) (GP/AH).

METHODS

Eighty-four roots from bilateral mandibular premolars were prepared. For fracture resistance, 40 teeth were randomly divided into 4 groups (n = 10 each): intact roots (negative control), prepared roots (positive control), and the roots obturated with either BCC/BCS or GP/AH. Root canals were obturated with the matched single-cone technique and vertically loaded with a spreaderlike tip until fracture. For push-out bond strength (n = 10 each), coronal, middle, and apical root slices of BCC/BCS and GP/AH were loaded with a cylindrical plunger, and failure modes were determined. Sealer penetration of BCC/BCS and GP/AH (n = 12 each) was evaluated for the maximum depth and the circumferential and total area of penetration at the coronal, middle, and apical levels using confocal laser scanning microscopy. The MOE was investigated according to ISO 4049:2000.

RESULTS

The fracture load of BCC/BCS, GP/AH, and the intact roots was not significantly different but significantly higher than the prepared, nonobturated roots. BCC/BCS provided a higher bond strength, maximum depth, and circumferential penetration at the apical root level as well as a greater sealer penetration area at all levels compared with GP/AH. The MOE of all materials was much lower than dentin.

CONCLUSIONS

BCC/BCS and GP/AH bonded and reinforced the prepared roots; their fracture resistances were similar to the intact roots.

Comparative evaluation of the vertical fracture resistance of endodontically treated roots filled with Gutta-percha and Resilon: a meta-analysis of in vitro studies

Background

Teeth treated endodontically are more susceptible to vertical root fracture (VRF). Some studies have suggested that obturating the root canals with Gutta-percha or Resilon can reinforce endodontically treated teeth, but a few others have presented conflicting results. These inconsistent results cannot guide clinicians in determining clinical approaches. The objective of this meta-analysis is to evaluate and compare the vertical fracture resistance of endodontically treated root canals obturated with Gutta-percha/AH plus and the Resilon system.

Methods

Comprehensive literature searches were performed in the PubMed, Cochrane Library, ScienceDirect, Web of Science and Embase databases. The titles and abstracts of all of the retrieved articles were independently assessed by two authors according to predefined selection criteria. Data in the included articles were independently extracted. Statistical analyses were conducted using Review Manager 5.3 and Stata 12.0 software. The pooled standardized mean differences (SMDs) with 95% confidence intervals (CIs) were calculated for the outcome indicators. The level of statistical significance was set at p < 0.05. The Cochran Q test (I² test) was used to test for heterogeneity among studies.

Results

Fourteen randomized controlled in vitro trials were included in the meta-analysis. The results demonstrated that the vertical root fracture resistance of unprepared and unfilled roots was significantly higher than that of roots obturated with Gutta-percha/AH plus (SMD = − 0.69, 95% CI = − 1.34 to − 0.04, p = 0.04) or the Resilon system (SMD = − 0.54, 95% CI = − 1.07 to − 0.00, p = 0.05). The differences in fracture resistance between the roots filled with Gutta-percha/AH plus and the prepared unfilled root canals was not significant (SMD = 0.59, 95% CI = − 0.02 to 1.21, p = 0.06). Roots obturated with Resilon had higher fracture resistance than instrumented unfilled roots (SMD = 0.83, 95% CI = 0.44 to 1.22, p < 0.0001) or roots filled with Gutta-percha/AH plus (SMD = 0.62, 95% CI = 0.01 to 1.23, p = 0.05).

Conclusions

The present study suggests that filling with Gutta-percha/AH plus dose not reinforce endodontically treated roots, whereas obturating with the Resilon system can increase vertical root fracture resistance of prepared roots. As this meta-analysis was based on in vitro studies, it should be careful to extrapolate its conclusion to the clinical context.

Ex vivo fracture resistance of teeth restored with glass and fiber reinforced composite resin

OBJECTIVES

This study aims to compare the ex vivo fracture resistance of root canal treated (RCT) teeth restored with four different types of fibers under composite resin.

SUBJECTS AND METHODS

One hundred and forty extracted mandibular first molar teeth were assigned to seven groups (n = 20/group). Group 1 was the control group. In groups 2-7, endodontic access and standard Mesio-occluso-distal (MOD) cavities were prepared. Following RCT, group 2 was left unrestored. In group 3, flowable composite resin (FCR) was used to line the cavities and restored with composite resin. In groups 4,5,6 and 7, Ribbond, Everstick, Dentapreg and Bioctris fibers were inserted in flowable resin and restored respectively.

RESULTS

All the groups restored with fiber reinforced composite displayed higher fracture resistance than the group restored with only composite resin (p < 0.001). In addition, Groups restored with Everstick and Bioctris (Groups 5 and 7) showed higher fracture resistance when compared to Ribbond and Dentapreg (Groups 4 and 6).

CONCLUSION

E glass fibers demonstrated highest fracture resistance and hence can be preferred over other fiber types to reinforce RCT teeth with weakened crown structures.

Comparative evaluation of Fracture Resistance of Endodontically Treated Teeth Obturated with Pozzolan-based MTA Sealer and Epoxy Resin-based Sealer: An in vitro Study

Aim

To evaluate and compare the effect of epoxy resin-based sealer and a pozzolan-based mineral trioxide aggregate (MTA) sealer on the fracture resistance of endodontically treated teeth.

Materials and methods

Thirty single-rooted mandibular premolars were decoronated to a standardized root length of 15 mm. ProTaper rotary files up to a master apical file size of F3 were used for cleaning and shaping the root canals followed by 2.5% sodium hypochlorite irrigation. The teeth were randomly divided into three groups (n = 10 each), and the obturation was completed using gutta-percha with Endoseal MTA (group I) and AH Plus (group II) as root canal sealers. Group III served as control (instrumented and unfilled). Each specimen was then subjected to fracture testing by using a universal testing machine at a crosshead speed of 1.0 mm/minute until fracture. The force required to fracture each specimen was recorded and the data were subjected to statistical analysis using one-way analysis of variance (ANOVA), followed by pairwise comparison using post hoc Games-Howell test (p < 0.05).

Results

The fracture resistance of groups I and II were significantly higher than those of group III. No significant difference in the fracture resistance was observed between group I (Endoseal MTA) and group II (AH Plus) groups.

Conclusion

It can be concluded that the new root canal sealer, Endoseal MTA, is able to reinforce the tooth against fracture as good as AH Plus.

Clinical significance

Endoseal MTA is a sealer for the reinforcement of endodontically treated teeth.

How to cite this article

Upadhyay ST, Purayil TP, Ginjupalli K. Comparative evaluation of Fracture Resistance of EndodonticallyTreated Teeth Obturated with Pozzolan-based MTA Sealer and Epoxy Resin-based Sealer: An in vitro Study. World J Dent 2017;8(1):37-40.

Effect of gaseous ozone and light-activated disinfection on the surface hardness of resin-based root canal sealers

Although root canal instruments remove most of the content from the main root canal space, disinfection or irrigation plays an indispensable role in all areas of the root canal system, especially in parts that are inaccessible by instruments. The originality of this study was to investigate the effect of two novel disinfection techniques on the surface hardness of resin-based endodontic sealers using atomic force microscopy (AFM). Forty extracted single-rooted maxillary central human teeth were prepared and divided into four groups according to treatment methods. The first group was irrigated with saline and served as a control, other groups irrigated with sodium hypochlorite (NaClO); gaseous ozone; and light-activated disinfection (LAD). The groups were divided into two subgroups, according to the obturation method used: subgroup A: gutta-percha and AH plus; and subgroup B: EndoREZ/resin-coated cones. After obturation, atomic force microscopy (AFM) measurement was performed to analyze the surface hardness of the sealers. There was a significant difference between group 1A and group 3A (p < 0.05). Group 3B had the highest surface hardness values that were statistically different (p < 0.05). When disregarding the sealers, the ozone possessed statistically higher surface hardness values than the other groups in all root thirds (p < 0.05). The use of ozone and LAD may alter the surface hardness of resin-based sealers. The use of AFM can be considered an alternative hardness test techonology for sealing material.

Fracture resistance of roots obturated with novel hydrophilic obturation systems

Aim:

Comparative assessment of fracture resistance of roots obturated with three hydrophilic systems — novel CPoint system, Resilon/Epiphany system, and EndoSequence BC sealer; and one hydrophobic gold standard gutta-percha/AHPlus system.

Materials and Methods:

Ninety freshly extracted, human, single-rooted mandibular premolars were selected. The specimens were decoronated and standardized to a working length of 13 mm. The teeth were randomly divided into six groups (n = 15). In Group A, teeth were left unprepared and unfilled (negative control). Rest of the groups were prepared by using ProTaper system up to a master apical file F3; followed by which Group B was left unobturated (positive control); Group C, novel CPoint System; group D, Resilon/Epiphany system, Group E EndoSequence BC sealer, and Group F gutta-percha and AH Plus. Specimens were stored for 2 weeks at 100% humidity. Each group was then subjected to fracture testing by using a universal testing machine. The force required to fracture each specimen was recorded and the data was analyzed statistically using analysis of variance (ANOVA) test and Tukey's post-hoc test.

Results:

The hydrophilic obturation systems have shown to exhibit significantly higher fracture resistance as shown by the values in Groups C, D, and E (P < 0.05) when compared with Group F. Within hydrophilic groups there was significant difference between Group D and Groups C and E (P < 0.05), while Groups C and E had no significant difference (P > 0.05).

Conclusion:

In contrast to hydrophobic systems, hydrophilic systems showed higher fracture resistance in a single-rooted premolar.

Comparative evaluation of fracture resistance of root obturated with resilon and gutta-percha using two different techniques: an in vitro study

INTRODUCTION

Present study evaluated the fracture resistance of endodontically treated teeth filled with Gutta percha and a new resin based obturating material (Resilon).

MATERIALS AND METHODS

A total of 150 freshly extracted Mandibular premolar with fully formed apices were selected and decoronated at cemento-enamel junction (CEJ). Teeth were divided into Group A and Group B of 75 teeth each. In Group A canals were prepared up to # no 40 K file and Group B up to #no 80 K file. Both the groups were sub divided into five group of 15 teeth each as control group (unfilled canals), lateral condensation with Gutta-percha using AH 26 sealer, vertical condensation with Gutta-percha using AH 26 sealer, lateral condensation with Resilon using resilon sealer, vertical condensation with Resilon using resilon sealer. Each specimen was subjected to compressive load using Universal testing machine. The force required to fracture was recorded and data were analysed by ANOVA, Duncan's test and student T test.

RESULT

The result showed that there is statistically significant difference among experimental groups (p < 0.05). The groups with the Resilon material displayed higher mean fracture loads than the Gutta percha groups. No statistically significant differences were observed between different preparation techniques.

CONCLUSION

Obturating the canals with the new resin-based obturation material increases the in vitro fracture resistance of endodontically treated teeth when compared with standard Gutta percha techniques.

Comparative evaluation of fracture resistance of root dentin to resin sealers and a MTA sealer: An in vitro study

Background:

Endodontic obturating materials should form monoblocks, reinforcing the treated teeth against fracture.

Aim:

To evaluate and compare the effect of two resin sealers and a MTA sealer on the fracture resistance of endodontically treated teeth.

Materials and Methods:

Fifty single-rooted mandibular premolars, decoronated at cemento-enamel junction, were divided into 5 groups (n = 10 each). Group 1 and group 2 served as negative and positive controls. Cleaning and shaping of root canals was done using ProTaper rotary files and 3% sodium hypochlorite irrigation. Obturation was done using AH plus (Dentsply, Germany) (group 3), MetaSEAL (Parkell, USA) (group 4), MTA Fillapex (Angeles, Brazil) (group 5) sealers and gutta-percha. Teeth were subjected to vertical loading using a universal testing machine and the point at which fracture of the roots occurred was recorded. The data was subjected to statistical analysis using one way analysis of variance (ANOVA) followed by pair-wise comparison using Tukey's Post-hoc test.

Results:

AH Plus showed better fracture resistance among the sealer groups. Statistically, no significant difference was found between MetaSEAL and Fillapex groups.

Conclusion:

MTA Fillapex as a root canal sealer was not able to reinforce the tooth against fracture.

A comparative assessment of fracture resistance of endodontically treated and re-treated teeth: An in vitro study

Aim:

To compare and assess the fracture resistance of endodontically treated teeth with those that have been subjected to endodontic retreatment.

Materials and Methods:

30 extracted mandibular premolars were decoronated at cementoenamel junction and randomly divided into 2 groups. In Group I endodontic treatment was performed with ProTaper rotary system till size F2 and obturated. In Group II, cleaning and shaping was done and teeth were subjected to Spiral CT to assess the remaining dentin thickness and obturated. Later retreatment was done using Protaper Universal Retreatment system and final shaping was performed till size F3. Remaining dentin thickness was again assessed using Spiral CT and then obturated. All the specimens were subjected to fracture resistance using universal testing machine. The results were statistically analyzed using Independent Samples t-test for analysis of remaining dentin thickness using SCT within Group II and Paired Samples t-test was used for assessment of fracture resistance between Group I and II (P < 0.05).

Results:

In Group II, the intra group comparison of the remaining dentin thickness in the coronal third reveals statistical significance, with a significant difference noted in the apical third. Results of the fracture resistance reveal a statistically significant difference (P < 0.05) between Groups I and II with the mean fracture resistance of Group I being higher than Group II.

Conclusion:

Endodontically retreated teeth have shown significantly decreased resistance to fracture and this has a positive correlation to the increased loss of root dentin during the retreatment procedures

In vitro fracture resistance of roots obturated with epoxy resin-based, mineral trioxide aggregate-based, and bioceramic root canal sealers

INTRODUCTION

The aim of this study was to evaluate the fracture resistance of teeth filled with 3 different endodontic sealers.

METHODS

Seventy-five single-rooted extracted mandibular premolars were decoronated to a length of 13 mm. The teeth were randomly divided into 5 groups (n = 15 for each group). In group 1, the teeth were left unprepared and unfilled (negative control), and in group 2, the teeth were left unobturated (positive control). The rest of the roots were prepared by using the ProTaper System up to a master apical file size of F3: group 3, bioceramic sealer (Endosequence BC sealer) + gutta-percha; group 4, mineral trioxide aggregate-based sealer (Tech Biosealer Endo) + gutta-percha; and group 5, epoxy resin-based sealer (AH Plus Jet) + gutta-percha. All root specimens were stored for 2 weeks at 100% humidity to allow the complete setting of the sealers. Each specimen was then subjected to fracture testing by using a universal testing machine at a crosshead speed of 1.0 mm/min(-1) until the root fractured. The force required to fracture each specimen was recorded, and the data were analyzed statistically.

RESULTS

The fracture values of groups 3 and 5 were significantly higher than those of group 4 (P < .05). There was no significant difference between groups 3 and 5 (P > .05).

CONCLUSIONS

In contrast to Tech Biosealer Endo, Endosequence BC and AH Plus Jet sealer increased the force to fracture in root-filled single-rooted premolar teeth.

Fracture resistance of overtly flaring root canals filled with resin-based obturation material

Background:

Reinforcement of root canals obturated with Resilon was reported by several investigators, but no studies reported the reinforcement of overtly flared root canals obturated with Resilon material. The aim of this study was to investigate the fracture resistance of overtly flared root canals filled with Resilon as compared to similar root canals filled with gutta-percha (GP).

Materials and Methods:

Sixty single-rooted premolars were divided randomly into six groups. Group 1 served as control group. The control group was sub-divided into two groups, a negative group and a positive group. The negative group consisted of root canals that were only cleaned from residual pulpal tissues, however, the positive group had prepared and overtly flared root canals without obturation. Groups 2 and 4 were shaped using 0.04 taper rotary files, while groups 3 and 5 were shaped using 0.06 taper rotary files. Before obturation, the last four groups were further flared coronally with a reverse cone diamond bur. Groups 2 and 3 were obturated with GP and a resin-based sealer, while groups 4 and 5 were obturated with Resilon and Epiphany self-etching primer and Epiphany sealer. Roots were then fixed into a universal testing machine and vertically loaded until fracture. SPSS software (Release 9.0 for Windows, SPSS, Chicago, USA) was used to perform the statistical analysis.

Results:

Fracture resistance measurements showed that there were differences in resistance to fracture among the experimental groups (ANOVA, P < 0.0001). Mean values of the loading force applied to the negative control group were the highest at 1.81 KN, whereas the mean values for the Resilon groups (Groups 4 and 5) at 1.13 KN and 1.54 KN were found to be higher than the GP groups (Groups 2 and 3) at 0.45 KN and 0.88 KN, respectively. Tukey's post hoc test showed that there was no statistical difference between the mean values of the negative control group and Group 5 (P = 0.69).

Conclusion:

Obturation of overtly flared roots with Resilon material increased the resistance of these teeth to vertical root fracture.

Resistance to vertical fracture of MTA-filled roots

AIM

To investigate the effect of MTA root canal fillings on the resistance to vertical root fracture (VRF) over different time intervals.

MATERIAL AND METHODS

Freshly extracted anterior human teeth with single canals and minimal curvatures were decoronated, instrumented to size 50/.05 ProTaper file, irrigated with 1%NaOCl and randomly allocated to one of three groups (n = 36): (i) filled with MTA, (ii) filled with gutta-percha and sealer and (iii) unfilled roots used as a negative control. Each group was subdivided into three subgroups (n = 12) according to the storage time of 48 h, 1 and 6 months at 37°C in synthetic tissue fluid (STF). Following the storage periods, filled roots were mounted in acrylic supports, and the periodontal ligament was simulated using elastomeric impression material. Vertical loading was carried out with a ball-ended steel cylinder fitted on a universal testing machine at 1 mm/min crosshead speed. The maximum force at fracture (F-max) and the fracture mode were recorded for each root.

RESULTS

Data were statistically analysed using two-way anova and Bonferroni post hoc tests. The mean F-max was significantly higher in the MTA subgroups after 1 and 6 months compared with all other subgroups. Two modes of fracture were identified: split and comminuted. The mean F-max values recorded with the latter were significantly higher compared with the former (P < 0.001). In all groups, split fracture was the most dominant mode apart from the MTA/1 month and MTA/6 month groups.

CONCLUSION

MTA increases the resistance to VRF of endodontically treated teeth and influences the mode of fracture after 1 and 6 month of storage in STF compared with gutta-percha and sealer.

An in vitro comparative evaluation of fracture resistance of endodontically treated teeth obturated with different materials

The aim of this study was to evaluate the in vitro effect of various obturating materials on fracture resistance of root canal treated teeth. Sixty freshly extracted human mandibular premolars were used. After standardizing the length to 13 mm, the teeth were biomechanically prepared and divided into four groups based on type of obturating materials used. Teeth were embedded in acrylic resin and fracture strength was measured using a universal testing machine. Data obtained was evaluated statistically using one-way ANOVA and the unpaired t-test. Teeth obturated with AH Plus and gutta percha showed higher fracture resistance than those obturated with Resilon-Epiphany. The results suggested that the group obturated with gutta percha and zinc oxide-eugenol sealer had the lowest fracture resistance. No statistically significant difference was found between the unobturated (control) group and the zinc oxide-eugenol group.

Influence of different restorative techniques on the strength of endodontically treated weakened roots

Objective. Comparing effect of different restoration techniques on fracture resistance of compromised roots. Methods. Crowns of 100 single-rooted teeth were sectioned and 10 roots were kept as negative control group (Group 1). Remaining roots were instrumented and divided into one and positive control group of 10 samples (Group 2) and 4 experimental groups of 20 samples each. Group 3: roots were obturated with gutta-percha; Group 4: roots were restored with gutta-percha, composite, and glass fiber post; Group 5: roots were obturated with Resilon; Group 6: Roots were restored with Resilon, composite, and glass fiber post. Roots were weakened before obturation in groups 2, 3, and 5 and after obturation in groups 4 and 6. Fracture strengths were measured using Dartec testing machine and fracture load was recorded in kilo-Newton. Statistical analysis was done using ANOVA and Tukeys test. Results. The fractures resistance of restored roots was significantly higher in groups 4, 5, and 6 than in Groups 2 and 3. There were no significant differences between groups 1, 4, 5, and 6. Conclusions. Restoration of weakened roots with Resilon or bonding an intermediate composite resin to coronal radicular dentin and to glass fiber post increased their fracture resistance.

A comparative evaluation of the vertical root fracture resistance of endodontically treated teeth using different root canal sealers: an in vitro study

OBJECTIVE

The objective of this study is to evaluate the vertical root fracture resistance of endodontically treated teeth obturated with - Tubli-Seal EWT/Gutta-percha, AH Plus/Gutta-percha, Epiphany SE sealer/Epiphany point.

STUDY DESIGN

Sixty-five single rooted premolars were decoronated and root length was 14 mm for each specimen. Fifty five teeth were enlarged up to ISO size 40 master apical file with stainless steel K-files using standardized preparation and remaining ten teeth were served as negative control. Then teeth were randomly assigned into different groups depending on sealer used for obturation as follows: Group 1: Negative control-no instrumentation was performed. Group 2: Positive control-gutta-percha with out the use of any sealer. Group 3: Experimental group-gutta-percha and Tubli-Seal EWT root canal sealer. Group 4: Experimental group-gutta-percha and AH Plus. Group 5: Experimental group-epiphany SE sealer and epiphany points. After 72 hours, the specimens were embedded in autopolymerizing resin leaving 7 mm of each root exposed and were subjected to fracture testing under universal testing machine at a crosshead speed of 1.0 mm per minute until the root fractured. Results were statistically analyzed using one-way ANOVA and independent t-test.

RESULTS

Showed that Epiphany SE sealer/Epiphany points showed highest mean fracture resistance and Tubli-Seal EWT group showed the least fracture resistance of all the materials tested. There was no statistically significant difference among experimental groups.

CONCLUSION

Epiphany SE sealer/Epiphany points demonstrated highest fracture resistance values than the other materials tested and intact tooth had highest resistance against vertical root fracture.

CLINICAL SIGNIFICANCE

Epiphany SE sealer/Epiphany points may be one of the materials of choice in the endodontic treatment of teeth.

Fracture resistance of roots filled with three different obturation techniques

Objectives: The aim of this study was to compare in vitro root fracture resistance following root canal filling with AH 26 using lateral condensation, BeeFill, and Thermafil techniques. Study Design: Eighty extracted human mandibular premolars with similar dimensions were selected. In order to standardize the roots, measurements were taken in two separate regions of the teeth—at the cemento-enamel junction and 8 mm apically from the junction—buccolingual as well as mesiodistal for every tooth. Teeth were then randomly divided into five groups (n=16). With the exception of the non-prepared group (Group 1), instrumentation was done in all groups. In group 2, instrumentation but no filling was performed; in group 3, the obturation was done with AH 26 + gutta-percha; in group 4, with AH 26 + BeeFill and in group 5, AH 26 + a Thermafil obturator was used. All the roots were mounted vertically in copper rings and filled with acrylic resin, exposing 8 mm of the coronal part. A universal testing machine was used for the strength test. Results: The results were analyzed using the one-way ANOVA test. The significance between the groups was tested with Temhane’s T2 test. The results indicate that instrumentation of root canals had a significant effect on fracture resistance (p<0.05). In addition, there were no differences between the root canal obturation techniques; furthermore, these techniques did not create a statistically important resistance to vertical fracture (p>0.05). Conclusions: The results suggest that instrumentation of root canals significantly weakens the tooth structure to fracture and the root canal obturation techniques that are used are not able to form reinforcement.

Key words:AH 26, obturation technique, vertical fracture.

Resistance to vertical root fracture of endodontically treated teeth with MetaSEAL

INTRODUCTION

The purpose of this in vitro study was to assess the influence of MetaSEAL and AH Plus on the resistance to vertical root fracture of endodontically treated teeth when either the matched-taper single-cone or lateral condensation technique was used.

METHODS

Ninety extracted single-canal mandibular premolar teeth were sectioned, leaving a standard root length of 13 mm. The buccolingual and mesiodistal diameters were measured, and the teeth were randomly divided into 6 groups (n = 15). There were no statistically significant differences between the groups in terms of the diameters. In group 1, no instrumentation or obturation was performed. The rest of the roots were chemomechanically prepared with nickel-titanium ProTaper rotary instruments up to size F3 at the working length. Group 2 was left unobturated. Groups 3 and 4 were obturated with AH Plus used with the matched-taper single-cone and lateral condensation techniques, respectively. In groups 5 and 6, MetaSEAL was used instead of AH Plus. All of the roots were mounted vertically in self-curing acrylic resin blocks that exposed 8 mm of the coronal part. Then the roots were subjected to a vertical loading force (1 mm/min). The force required to produce a fracture was recorded in newtons. The data were analyzed by using Kruskal-Wallis and post hoc Dunn multiple comparison tests (P < .05).

RESULTS

Although we did not detect statistical significance, there was a substantial difference between the fracture resistance values of the intact and instrumented but not obturated roots. The groups in which AH Plus and MetaSEAL were used with the matched-taper single-cone technique showed significantly higher fracture resistance values than the instrumented but not obturated roots (P < .05). There were no significant differences between the groups submitted to the matched-taper single-cone technique. The force required to fracture the roots in the group treated with AH Plus and the lateral condensation technique was similar to that required to fracture intact roots, whereas the group treated with MetaSEAL and the lateral condensation technique revealed comparable values to the instrumented but not obturated roots.

CONCLUSIONS

When used with the matched-taper single-cone technique, MetaSEAL and AH Plus have the potential to reinforce endodontically treated teeth.

Fracture susceptibility of endodontically treated teeth

AIM

To assess the influence of cervical preparation on fracture susceptibility of roots.

MATERIAL AND METHODS

During root canal instrumentation, the cervical portions were prepared with different taper instruments: I: no cervical preparation; II: #30/.08; III: #30/.10; IV: #70/.12. The specimens were sealed with the following filling materials (n = 8), A: unfilled; B: Endofill/gutta-percha; C: AH Plus/gutta-percha; D: Epiphany SE/Resilon. For the fracture resistance test, a universal testing machine was used at 1 mm per minute.

RESULTS

anova demonstrated difference (P < 0.05) between taper instruments with a higher value for group I (205.3 ± 77.5 N) followed by II (185.2 ± 70.8 N), III (164.8 ± 48.9 N), and IV (156.7 ± 41.4 N). There was no difference (P > 0.05) between filling materials A (189.1 ± 66.3 N), B (186.3 ± 61.0 N), C (159.7 ± 69.9 N), and D (176.9 ± 55.2 N).

CONCLUSIONS

Greater cervical wear using a #70/.12 file increased the root fracture susceptibility, and the tested filling materials were not able to restore resistance.

Fracture resistance of teeth obturated with Gutta percha and Resilon: An in vitro study

Aim:

The aim of this study was to evaluate and compare the fracture resistance of endodontically treated teeth filled with gutta percha and Resilon.

Materials and Methods:

A total of 60 freshly extracted single rooted teeth are selected and their anatomical crown removed at the CEJ. All samples were instrumented with the Step-back technique. Samples were randomly divided into three groups of 20 samples each: Group A obturated by lateral condensation with gutta percha and AH plus sealer, Group B obturated by lateral condensation with Resilon; Group C recieved no filling. Restored teeth were subjected to compressive loading in a universal testing machine. The results of fracture resistance recorded and statistical analysis done.

Results:

The mean and SD values for the groups are as follows: Group A-536.555 ± 128.816, Group B- 885.943 ± 194.410 and Group C- 591.066 ± 68.97. It was seen that samples of Group B showed the highest fracture resistance followed by Group C. Group A showed the least fracture resistance.

Conclusion:

The results of this study showed that filling the canals with Resilon increased the in vitro resistance to fracture of endodontically treated single canal teeth when compared with gutta percha.

Effect of sealers on fracture resistance of endodontically treated teeth with and without smear layer removal: An in vitro study

Aim:

The present study involved the in vitro comparison of root reinforcing abilities of two sealers, i.e., Ketac-Endo and Acroseal, in endodontically treated teeth in the presence and absence of smear layer.

Materials and Methods:

Fifty teeth were taken and sectioned at the cementoenamel junction. The teeth with faults were discarded and a total of 36 teeth were used for study. The samples were biomechanically prepared using step-back technique. In 10 teeth, the smear layer was preserved using sodium hypochlorite. Smear layers were removed from 10 teeth using 17% EDTA, and in another 10 samples, the smear layers were eliminated using 17% EGTA. The remaining samples served as controls. Samples were obturated with sealers using the lateral condensation technique. Ketac-Endo (3M) is a glass ionomer based root canal sealer, and Acroseal (Septodont) sealers were used. The teeth were then tested by using an Instron testing machine.

Results:

Ketac-Endo shows higher fracture resistance values in comparison to Acroseal. Other factors as the amount of tooth structure remaining, the agents used for the removal of smear layer and instrumentation techniques may alter the tooth resistance to fracture.

Conclusion:

Ketac-Endo shows higher fracture resistance values in comparison to Acroseal.

In vitro resistance to fracture of roots obturated with Resilon or gutta-percha

INTRODUCTION

There have been varied results from studies comparing postendodontic fracture resistance between teeth obturated with Resilon or gutta-percha. This study was performed to evaluate the fracture resistance of roots obturated by using Resilon (RealSeal system) or gutta-percha (with AH Plus sealer).

METHODS

Eighty extracted human mandibular single-rooted premolars stored in 10% formalin were used in the study. They were prepared by using a crown-down technique, debrided with NaOCl, ethylenediaminetetraacetic acid, and sterile water and divided into 4 groups. Obturation was performed by using the lateral condensation method. The negative control group consisted of unfilled specimens, and the positive control group consisted of those obturated with flowable, dual-cure composite resin. All root specimens were stored for 2 weeks in 100% humidity to allow complete setting of the sealer. Each specimen was mounted in acrylic in a polyvinyl ring and tested for fracture resistance with the Universal testing machine. The loading fixture of the machine was mounted with its spherical tip aligned with the center of the canal opening of each root. A vertical loading force was applied until it fractured the root. The force values were subjected to statistical analysis including analysis of variance and Fisher least significant difference testing.

RESULTS

Teeth obturated with Resilon were more resistant to fracture than those obturated with gutta-percha. The difference was found to be highly significant (P=.00001).

CONCLUSIONS

Resilon increased the resistance to fracture of single-rooted teeth in vitro.

Dentine removal in the coronal portion of root canals following two preparation techniques

AIM

To measure the root canal area and the reduction of the mesial and buccal/lingual wall thickness at the level of the coronal interference in mesial roots of mandibular molars after instrumentation with a crown-down or a simultaneous root canal preparation technique.

METHODOLOGY

Twenty mesial roots of first mandibular molars with a moderate root canal curvature were embedded in resin and sectioned horizontally at the level of the coronal interference, using a modification of the Bramante technique. After scanning and processing, the sections were reassembled. One root canal of each root was prepared using ProTaper instruments, while Mtwo instruments were used in the other root canal of the same mesial root. After scanning and processing, the data obtained were analysed for two parameters: changes in root canal area after instrumentation (Delta A) and reduction of the mesial and buccal/lingual wall thickness (Delta T). The data were subjected to Student's t-tests for statistical analysis at a significance level of P < 0.05.

RESULTS

No statistically significant differences were found between the two groups with respect to the changes in the areas (Delta A) at the level considered (P = 0.410). No statistically significant differences were noticed between the two groups for dentine thickness (Delta T) of both the mesial wall (P = 0.077) and the buccal or lingual wall (P = 0.171).

CONCLUSIONS

There was no difference between the ProTaper and Mtwo groups for the amount of dentine removed.

Endodontic materials

This article presents a review of materials currently used in the practice of endodontics. Current endodontic materials include those that have been thoroughly tested by scientific investigation, clinical usage, and time, as well as others that are the result of new knowledge in the field of dental materials. Article sections are devoted to obturation materials, sealers, irrigation materials, smear layer removal, root-end filling materials, and intracanal medicaments. Knowing the particular qualities of materials can aid the clinician in choosing those that are appropriate for a given situation. Properties, components, and rationale for the materials' use are presented to aid the clinician in choosing materials for a particular need.

Contemporary treatment of class II dens invaginatus

AIM

To present the nonsurgical management of a tooth with class II dens invaginatus with an open apex utilizing contemporary techniques.

SUMMARY

Root canal treatment of teeth with complex root canal anatomy such as dens invaginatus can be problematic because infected pulpal tissues may remain in inaccessible areas of the canal system. The cleaning and debridement of such root canal systems are therefore challenging and may sometimes be considered impossible. An immature apical root-end development is another challenge in root canal treatment especially in controlling the apical extent of the filling material and achieving an apical seal. When difficulties in cleaning and filling combine, management options may include surgical intervention or extraction. This article reports the nonsurgical endodontic treatment of a case of an open apex and dens invaginatus utilizing the operating microscope, endodontic ultrasonic instruments and mineral trioxide aggregate.

KEY LEARNING POINT

Teeth with class II dens evaginatus and an open apex may be managed successfully with contemporary nonsurgical materials and techniques.

Monoblocks in root canals: a hypothetical or a tangible goal

The term monoblock has become familiar in the endodontic literature with recent interest in the application of dentin adhesive technology to endodontics. Endodontic monoblocks have generated controversial discussions among academicians and clinicians as to whether they are able to improve the quality of seal in root fillings and to strengthen roots. This review attempts to provide a broader meaning to the term monoblock and to see how this definition may be applied to the materials that have been used in the past and present for rehabilitation of the root canal space. The potential of currently available bondable materials to achieve mechanically homogeneous units with root dentin is then discussed in relation to the classical concept in which the term monoblock was first employed in restorative dentistry and subsequently in endodontics.

Influence of resin-based adhesive root canal fillings on the resistance to fracture of endodontically treated roots: an in vitro preliminary study

OBJECTIVE

The aim was to investigate the root reinforcing capability of the resin-based RealSeal.

STUDY DESIGN

In two groups (n=36) canals were instrumented with nickel-titanium rotary GTfiles or with hand K-files. Twelve teeth from each group were obturated with lateral compaction using either gutta-percha and AHPlus or RealSeal. The canals of twelve teeth of both groups were instrumented but not filled. Group 3 (n=12) acted as uninstrumented controls. The force required to fracture the roots was measured. ANOVA and Scheffé test were used for statistical analysis.

RESULTS

The intact roots were significantly stronger than both groups with instrumented and unobturated roots (P<.05). Between the roots of both groups obturated with RealSeal and the intact roots there were no significant differences (P>.05). The roots obturated with RealSeal were significantly stronger than those obturated with gutta-percha and AHPlus (P<.05).

CONCLUSIONS

An obturation with RealSeal significantly increases the fracture resistance of instrumented roots.

Resistance to fracture of roots filled with three different techniques

AIM

To compare the fracture resistance of roots filled with different materials.

METHODOLOGY

Thirty-four freshly extracted human maxillary central incisor teeth with similar dimension were selected. Crowns were sectioned at the cemento-enamel junction, and the length of the roots were adjusted to 13 mm. Following the preparation of the root canals and final irrigation with EDTA and saline, the 10 root canals in group 1 were filled with Resilon cones and Epiphany sealer, the 10 root canals in group 2 were filled with gutta-percha and AH 26 and the 10 root canals in group 3 were filled with gutta-percha and MCS Canal Sealer. All materials were used with a cold lateral condensation technique. Four root canals remained unfilled and were used as a control group. Tests for fracture strength were performed using a universal testing machine and a round tip that had a diameter of 4 mm. The force was applied vertically with a constant speed of 1 mm min(-1). For each root, the force at the time of fracture was recorded in Newtons. Results were evaluated statistically with ANOVA and Tukey Honestly Significant Difference (HSD) tests.

RESULTS

The mean force of fracture values was 1043 N, 967 N, 859 N and 517.5 N for groups 3, 1 and 2 and the control group, respectively. There was a significant difference (P < 0.01) between the experimental groups and the control group. No significant differences were found between the three experimental groups.

CONCLUSIONS

All the materials used in the present study reinforced the prepared root canals.

Influence of instrument taper on the resistance to fracture of endodontically treated roots

OBJECTIVE

The aim was to compare the force required to fracture uninstrumented and instrumented canines and to investigate the root-reinforcing capability of AH Plus sealer.

STUDY DESIGN

In groups 1-3 (n = 24) canals were instrumented with either GT files, FlexMaster, or stainless steel hand instruments. Twelve teeth from each group were obturated with lateral compaction using gutta-percha and AH Plus. Group 4 (n = 12) acted as uninstrumented controls. The force required to fracture the roots was measured. ANOVA, Scheffé, and t test were used for statistical analysis.

RESULTS

The intact roots were significantly stronger than all groups with instrumented and unobturated roots (P < .05). Roots enlarged with GT files were significantly weaker (P < .05) than those instrumented with FlexMaster or hand instruments. Between the obturated and unobturated roots there were no significant differences (P > .05).

CONCLUSIONS

The roots were significantly weakened by the preparation with greater taper instruments. An obturation with AH Plus did not increase the fracture resistance.

Fracture resistance of roots endodontically treated with a new resin filling material

BACKGROUND

The authors evaluated the fracture resistance of endodontically treated teeth filled with either gutta-percha or a new resin-based obturation material.

METHODS

The authors prepared and randomly divided 80 single-canal extracted teeth into five groups: lateral and vertical condensation with gutta-percha, lateral and vertical condensation with the new resin-based obturation material, and a control group with no filling material. The specimens were stored in 100 percent humidity for two weeks, mounted in polyester resin and loaded to failure.

RESULTS

The authors found statistically significant differences among the experimental groups (P < .05). The groups with the new material displayed higher mean fracture loads and the gutta-percha groups lower mean fracture load values than the control unfilled group. However, the differences were not significant. The groups with the new material displayed significantly higher mean fracture loads than gutta-percha groups independent of the filling technique used.

CONCLUSIONS

Filling the canals with the new resin-based obturation material increased the in vitro resistance to fracture of endodontically treated single-canal extracted teeth when compared with standard gutta-percha techniques. CLINICAL IMPLICATIONS; If other properties of the new resin-based obturation material compare favorably with those of gutta-percha for filling the root canal, it should be considered as a replacement for gutta-percha, as the results of this study indicate that it could provide enhanced resistance to tooth fracture.

Comparison of mandibular premolars and canines with respect to their resistance to vertical root fracture

OBJECTIVE

To compare the force required to vertically fracture uninstrumented and instrumented mandibular premolars and canines.

METHODS

Two groups of single round-canal mandibular premolars and two groups of single oval-canal mandibular premolars were selected after radiographs indicated an internal long:short diameter of 1 or >2 at a level 5 mm from the apex. In addition, two groups of maxillary and mandibular canines were selected. The root canals of three of these groups (one from each category) were conventionally enlarged using same-sized instruments, while the other three groups were uninstrumented. Each root was mounted in an acrylic resin cylinder, and the force required to cause vertical root fracture (VRF) was measured using an Instron tester.

RESULTS

No significant difference in resistance to VRF was found between the round- and oval-canal premolars with (p = 0.9) or without (p = 0.6) instrumentation. The average force required to fracture the uninstrumented premolars and canines was 698 and 566 N, respectively. The average force required to fracture the instrumented premolars and canines was 490 and 554 N, respectively. The force required to fracture the instrumented premolars and canines was 30% (p < 0.05) and 2% (p = 0.9) lower, respectively, than that required to fracture their uninstrumented counterparts.

CONCLUSIONS

The instrumented mandibular premolars have a higher risk to fracture than the uninstrumented mandibular premolars.