Gutta-percha Points Research Articles

Root canal treatment of mandibular second premolars with three root canals: Report of four rare cases

Background/Aim: The aim of root canal treatment is the thorough cleaning, shaping and obturation of the root canals. Variations in root canal anatomy increase the difficulty of the root canal treatment and therefore the possibility of failure. The mandibular premolars often present complex anatomy and the existence of mandibular second premolars with three root canals is very scarce. This report presents the successful endodontic management of four mandibular second premolars with three root canals. Cases Report: In all cases working length was estimated using the working length radiograph and an apex locator. Canal orifices were enlarged with Gates-Glidden drills and manual instrumentation performed with Stainless Steel reamers and Hedstroem files, using either step-back or crown-down technique. Sodium hypochlorite (NaOCl) 2.5% was used as an irrigant. Root canal obturation were then performed using the cold lateral condensation technique with gutta-percha points and Roth's 801 canal sealer. The cases were scheduled for clinical and radiographic follow-up examination. Clinically in all follow-up examinations the teeth were asymptomatic. For the three cases with periapical lesions, post treatment radiographs, demonstrated periapical healing. Additionally, in the case without periapical lesion, the 9 months recall radiograph revealed healthy periapical conditions. Conclusions: Mandibular premolars should never be underestimated and the clinician should always be alerted for anatomic variations.

Ion Release From Prototype Surface Pre-Reacted Glass Ionomer (S-PRG) Sealer and EndoSequence BC Sealer.

Objective:Bioactive ions, when incorporated in an endodontic sealer, can contribute to the long-term success of endodontic therapy by combating the re-infection of a tooth and promoting the healing of the periapical bone. The objective of this study was to measure the release of boron, strontium, and silicon ions from surface pre-reacted glass ionomer (S-PRG) filler containing prototype endodontic sealer over a sustained period in comparison to EndoSequence BC sealer in a simulated clinical model using extracted human teeth in vitro.Methods:Twelve extracted human anterior teeth were instrumented using ProTaper Next (Dentsply Sirona, Johnson City, TN, USA) files up to size X3 (#30/variable taper) with copious 2.5% NaOCl irrigation. Teeth were obturated using a single-cone technique with a matching size tapered gutta-percha point and one of two endodontic sealers: prototype S-PRG (Shofu Inc., Kyoto, Japan) or EndoSequence BC (Brasseler, Savannah, GA, USA). The teeth were soaked in phosphate-buffered saline (PBS) solution for 336 hours. Periodically, 1-mL samples of the PBS were analyzed via an inductively coupled plasma mass spectrometer to determine the concentrations of ions released by the sealers.Results:The average (S.D.) cumulative release (ng/ml) of boron, silicon, and strontium ions over 2 weeks for the prototype S-PRG sealer was 8614.9 (1264.3), 35758.9 (5986.5), and 3965.2 (145.6), and for EndoSequence BC sealer was 1860.5 (82.7), 164648.7 (16468.1), and 227.7 (4.7). Generalized linear mixed model analysis showed significant differences in ion concentration among boron, silicon, and strontium over time between the two sealer groups (Boron: P<0.0001, Silicon: P=0.010, Strontium: P=0.028). Of the three ions, strontium had the lowest amount of release for both sealers. The prototype S-PRG sealer showed a rapid initial burst followed by a slow, continuous release of strontium ions.Conclusion:The prototype S-PRG sealer released boron and strontium ions in higher cumulative concentrations over 2 weeks compared to the EndoSequence BC sealer. Both the prototype S-PRG and EndoSequence BC sealers released silicon ions, although significantly more were eluted from the EndoSequence BC sealer. Antimicrobial and osteogenic ion release from sealers is expected to positively influence the post-treatment control of microbial infections to improve periapical healing.

Management Of Perforating External Cervical Root Resorption

Introduction: External cervical resorption (ECR) is the loss of dental hard tissue as a result of odontoclastic action; it usually begins on the cervical region of the root surface of the teeth. The etiology and predisposing factors are not very clear. The aim of this case report is to show the management of maxillary right canine diagnosed with ECR. Case Report: A 54-year old female patient was referred to our clinic with the history of dentin hypersensitivity in maxillary right anterior area. Radiographic examination revealed a radiolucent lesion located on the cervical third of maxillary right canine. The tooth was clinically asymptomatic. The patient did not report any traumatic history. CBCT scans revealed the extent of the resorption cavity and confirmed the diagnosis of the lesion. Due to perforation of the resorption into the root canal space, the access cavity was opened and temporarily occluded with a gutta-percha point. Then the surgical repair of the resorptive defect was carried out without blocking the root canal with filling material. A mucoperiosteal flap was elevated to clean the granulamatous tissue. The lesion was apparent after complete degranulation of soft tissue. It was repaired with MTA-Angelus (Angelus, Londrina, PR, Brazil) , a glass ionomer and a composite resin. The flap was replaced and sutured. Once the ECR cavity was restored, then endodontic treatment was completed in the same appointment. The root canal was obturated with gutta percha and root canal sealer by cold lateral condensation. . Conclusion: In the 9-month follow-up examination, the tooth including ECR defect was completely asymptomatic and functional. Early detection is necessary for successful management and outcome of ECR. CBCT should be considered for the assessment and/or management of ECR.

Non-surgical Removal of Dens Invaginatus in Maxillary Lateral Incisor Using CBCT: Two-year Follow-up Case Report.

A 14-year female presented with an atypical looking tooth #7 with a sinus tract on tooth #8. A gutta-percha point inserted into the sinus tract confirmed the affected tooth #7. A radiographic examination of tooth showed a lateral radiolucency with respect to tooth #7. Cone-beam computed tomographic imaging was done for the three-dimensional reconstruction analysis. Dens invaginatus (Oehler’s type III) with pulp necrosis and chronic apical periodontitis was the definitive diagnosis. Use of the dental operating microscope and ultrasonics helped in the removal of the invaginated structure. At the two year follow-up, no clinical and radiographic evidence of infection was observed.

Dentinal Tubule Penetration and Retreatability of a Calcium Silicate–based Sealer Tested in Bulk or with Different Main Core Material

IntroductionThe aim of this study was 2-fold: to evaluate the penetration of a tricalcium silicate–based endodontic sealer (EndoSequence BC Sealer; Brasseler USA, Savannah, GA) into dentinal tubules without a core material (sealer) or with .02 or .04 tapered bioceramic gutta-percha points and to compare the time required to remove the root fillings . MethodsRoots of extracted human mandibular incisors (N = 60) were prepared with 0.04 taper nickel-titanium rotary files to #35 and randomly assigned into 3 groups (n = 10/group) according to the obturation method used:1. obturating with sealer only,2. sealer + .02 point, and3. sealer + .04 point. The sealer was labeled with rhodamine B for analyzing dentinal tubule penetration under a confocal laser scanning microscope. The remaining specimens (n = 30) were used to measure the time for removal of the root canal fillings with retreatment files. The data were analyzed using 1-way analysis of variance and post hoc Games-Howell tests for dentinal tubule penetration and the Kruskal-Wallis test for retreatment time. ResultsSignificantly greater sealer penetration and sealer-penetrated area was achieved when the sealer was used with a .04 gutta point (P < .05), whereas there was no difference between the sealer and .02 gutta point groups (P > .05). All test groups showed a similar depth of sealer penetration (P > .05). Groups with the gutta-percha points required a similar time to remove root filling (P > .05), whereas the working length could not be achieved in the sealer group. ConclusionsThe use of a matched-taper bioceramic gutta-percha point enhanced the dentinal tubule penetration of the tested tricalcium silicate–based sealer. The use of a core material in conjunction with sealer facilitates removal of the root filling to the working length.

Porosity Distribution in Apically Perforated Curved Root Canals Filled with Two Different Calcium Silicate Based Materials and Techniques: A Micro-Computed Tomography Study.

The present study evaluated the porosity distribution of BioRoot RCS/single gutta-percha point (BR/SC) and MTA flow (MF) fillings, which were used as plugs for the apical perforation repair in curved canals of extracted mandibular molars using micro-computed tomography (μCT). Forty mesial root canals of mandibular first molars were shaped with ProTaper NEXT X1–X5 files 2 mm beyond the apex to simulate apical perforations that were randomly divided into two groups (n = 20) according to the material and technique used for the apical plug: BR/SC or MF. The specimens were scanned before and after canal filling at an isotropic resolution of 9.9 μm. The volumetric analysis of voids in the apical 5 mm of the fillings was performed. Data were analyzed using one-way ANOVA with Bonferroni correction (p < 0.05). Micro-computed tomography (µCT) evaluation revealed significant differences between the groups in terms of porosity: the total volume and percentage volume of voids was lower in the BR/SC group in comparison with the MF group (p < 0.05), with the predominance of open pores in both groups. Neither of the materials and/or application techniques were able to produce void-free root fillings in the apical region of artificially perforated curved roots of mandibular molars.

Cone Beam Computed Tomography in the Analysis of Endodontic Treatment of Teeth (in an Experiment)

Objective. To determine peculiarities when using microfocus cone beam computed tomography (micro-CBCT) and cone beam computed tomography (CBCT) to analyze the anatomy of the teeth and the quality of endodontic treatment.Material and methods. Micro-CBCT and CBCT were experimentally used to examine 8 extracted tooth preparations before and after endodontic root canal treatment using different types of filling material.Results. Micro-CBCT showed the high informative value of determining the type, nature, and quality of canal filling and diagnosed many cracks and accessory canals. According to the micro-CBCT findings, the tooth apexes were not filled; the lumen of the canals was unevenly and loosely filled with endodontic material; the passages of guttapercha points were well traced; the nature of the endodontic material was differentiated.Conclusion. Micro-CBCT opens up new opportunities in dentistry with tooth volume visualization, allowing the minor and low-contrast details of the anatomical structure of the teeth to be seen on the X-ray image.

New gutta percha composite with high thermal conductivity and low shear viscosity contributed by the bridging fillers containing ZnO and CNTs

Gutta percha (GP) point is typically used as the filling material during the root canal therapy, as its malleable, inert, and biocompatible properties. However, due to its low thermal conductivity (TC) and high shear viscosity, the vimineous GP point is difficult to melt and to flow into the root canal. In this study, a new GP composite with high TC and low shear viscosity is prepared by mixing a large amount of zinc oxide (ZnO) fillers bridged by a small quantity of carbon nanotubes (CNTs) (GP/ZnO@CNTs). Compared with the GP composite filled by ZnO alone (450phr), the TC of GP composite increases by 75.6% with 400phr ZnO and 50phr CNTs. Moreover, the TC and shear viscosity of GP composite containing 400phr ZnO and 20phr CNTs are 9.3% more and 4.5% less than those of a common commercial GP point (Bio-gutta percha (BP) point), respectively. The in vitro experiments confirm that the GP/ZnO@CNTs possesses the large filling depth of lateral canal, which is 9.0% longer than that of BP point at position WL-3. The cytotoxicity of the new GP composite extracts is grade 0–1, indicating that the material is qualified to prepare the GP point.

Artifact induction by endodontic materials

Metallic objects, such as intracanal posts and restorations, may produce severe interference, thus diminishing the quality of CBCT imaging. Objective: The purpose of this study was to analyze the influence of conventional and bioceramic gutta-percha points on the production of artifacts in CBCT images. Methods: Extracted single- -rooted premolar teeth (n=20) were instrumented and scanned with a CBCT device to create three groups: the Control group, the Gutta-Percha group and the Bioceramic Gutta-Percha group. Two types of analysis were executed: an objective one, using the Region of Interest (ROI) to measure the pixel density of each tooth, and a subjective one, to compare the groups’ images. For the statistical analysis, Student’s t-test, descriptive statistics and the frequency distribution analysis were used for both objective and subjective analyses. Results: The agreement between the observers ranged from moderate to excellent. Similar grayscale values were obtained in both the GP and BCGP groups. These results were endorsed by the p-values obtained with Student’s t test. For the subjective analysis, the observers indicated the BCGP group as the one that developed the highest number of artifacts. Conclusions: Both materials produced artifacts in the CBCT images. However, in the subjective analysis, the BCGP group showed higher levels of artifact production than the GP group, which could result in the misdiagnosis of root fracture and in a worse prognosis for that tooth.

Influence of Two Root Canal Obturation Techniques with Resin Based Sealer to Enterococcus faecalis Penetration

&#x0D; Introduction: Root canal treatment is done to maintain the teeth to last as long as possible in the oral cavity. This can be done with three main stages, such as biomechanical preparation, sterilization and root canal filling. The hermetic seal of root canal filling has an important role in the success of root canal treatment.&#x0D; &#x0D; Objective: The aim of this in-vitro study is to compare the microbial leakage of root canals filled with RealSeal sealer/Resilon Points and AH Plus sealer/conventional gutta-percha points using single cone obturation technique and warm vertical compaction technique.&#x0D; &#x0D; Methods: Thirty-two extracted human mandibular premolars with single canals were decoronated to a standardized root length of 15 mm and prepared using crown-down technique to a master apical file size 30/.09. Teeth were divided into four experimental groups (n = 7 each group) and controls (n = 1 each group). Teeth in the first group were obturated using single master gutta percha cone and AH Plus sealer and second group were obturated with single Resilon gutta percha cone using RealSeal sealer. Third experimental group was filled with warm vertical condensed gutta-percha using AH Plus sealer and fourth group was filled with warm vertical condensed Resilon gutta-percha using RealSeal sealer. The coronal chamber of each sample were inoculated with Enterococcus faecalis.&#x0D; &#x0D; Results: There were no significant differences between the four experimental groups (P = 0.182). The differences occurred only in the survival time from each group. Group 4 (Warm Vertical Condensation - RealSeal) has the lowest leakage rate among other groups and the fastest leakage occurred in group 1 (Single Cone - AH Plus).&#x0D; &#x0D; Conclusion: The single-cone techniques does not insure durable apical seal against bacterial leakage. Warm vertical compaction technique using Resilon gutta-percha and RealSeal sealer appears to be more effective in minimizing bacterial leakage than gutta-percha and AH Plus sealer.

Influence of Two Root Canal Obturation Techniques with Resin Based Sealer to Enterococcus faecalis Penetration

Introduction: Root canal treatment is done to maintain the teeth to last as long as possible in the oral cavity. This can be done with three main stages, such as biomechanical preparation, sterilization and root canal filling. The hermetic seal of root canal filling has an important role in the success of root canal treatment. Objective: The aim of this in-vitro study is to compare the microbial leakage of root canals filled with RealSeal sealer/Resilon Points and AH Plus sealer/conventional gutta-percha points using single cone obturation technique and warm vertical compaction technique. Methods: Thirty-two extracted human mandibular premolars with single canals were decoronated to a standardized root length of 15 mm and prepared using crown-down technique to a master apical file size 30/.09. Teeth were divided into four experimental groups (n = 7 each group) and controls (n = 1 each group). Teeth in the first group were obturated using single master gutta percha cone and AH Plus sealer and second group were obturated with single Resilon gutta percha cone using RealSeal sealer. Third experimental group was filled with warm vertical condensed gutta-percha using AH Plus sealer and fourth group was filled with warm vertical condensed Resilon gutta-percha using RealSeal sealer. The coronal chamber of each sample were inoculated with Enterococcus faecalis. Results: There were no significant differences between the four experimental groups (P = 0.182). The differences occurred only in the survival time from each group. Group 4 (Warm Vertical Condensation - RealSeal) has the lowest leakage rate among other groups and the fastest leakage occurred in group 1 (Single Cone - AH Plus). Conclusion: The single-cone techniques does not insure durable apical seal against bacterial leakage. Warm vertical compaction technique using Resilon gutta-percha and RealSeal sealer appears to be more effective in minimizing bacterial leakage than gutta-percha and AH Plus sealer.

Influence of final irrigation protocols and endodontic sealer on bond strength of root filling material with root dentin previously treated with photodynamic therapy.

The aim of this study was to evaluate the influence of final irrigation protocols and endodontic sealer on bond strength of root filling material on root dentin previously treated with photodynamic therapy (PDT). One hundred root canals were prepared up to #F3 file of Pro-Taper system to receive the root filling material. All samples were submitted to PDT and randomly divided into five groups (n = 20) according to final irrigation protocols: Group 1-distilled water + ultrasonic activation (US); Group 2-17% EDTA; Group 3-QMix; Group 4-17% EDTA + US; Group 5-QMix + US. Each group was randomly divided into two subgroups (n = 10), according to the endodontic sealer used for cementation of gutta-percha points: AH Plus or MTA Fillapex. The bond strength was evaluated by a push-out test. The patterns of failure were observed under optical microscopy. The bond strength was evaluated using a two-way Anova followed by the Tukey post-hoc test, and the failure mode was evaluated using the chi-square test (α = 5%). The use of 17% EDTA and QMix associated or not to US improved the bond strength of root filling material with either endodontic sealer (p < 0.05). AH Plus showed higher bond strength than MTA Fillapex (p < 0.05). There was a higher predominance of cohesive failure in all groups, regardless of the tested final irrigation protocols and endodontic sealer (p < 0.05). The use of 17% EDTA and QMix, regardless of association with US, and the use of AH Plus improve the bond strength of the root filling material on root dentin previously treated with PDT.

Effect of CPoint, EndoSequence BC, and Gutta-percha Points on Viability and Gene Expression of Periodontal Ligament Fibroblasts.

Objective:This study aimed to investigate the cytotoxic and biomodulatory potential of conventional gutta-percha (CGP) points, gutta-percha points containing bioceramics (BC), and CPoint polymer (CP) points on periodontal ligament (PDL) cells in vitro.Methods:PDL fibroblasts were cultured and stimulated with extracts of CGP, BC, and CP in serial dilutions to evaluate cell viability using MTT assay. Next, the 1:5 dilution was used to stimulate the cells for 72 h to assess the gene expression of type I collagen (COL-1) and cement protein 1 (CEMP-1), by reverse transcription followed by quantitative PCR. Data were statistically analyzed using one-way analysis of variance (ANOVA) (P<0.05).Results:Pure extracts of CGP and CP were found to be cytotoxic for PDL (P<0.01). Once diluted to 1:5, only CP showed cytotoxicity. BC did not affect cell viability in any extract sample. No extract significantly altered the gene expression of COL-1. For CEMP-1, a significant increase in gene expression was observed only for CGP (P<0.05).Conclusion:CP was found to be more cytotoxic than CGP, while BC demonstrated no cytotoxicity. The tested cones did not affect COL-1 gene expression, while CGP upregulated CEMP-1. Our results suggest that obturation point components may affect the biological responses of PDL fibroblasts.

The Effects of Different Agitation Techniques of Canal Irrigant on Tubular Penetration of a Bioceramic Sealer.

This study aimed to compare the effects of different agitation techniques of sodium hypochlorite (NaOCL) as the final irrigation with XP-Finisher file, passive ultrasonic irrigation (PUI), Er:YAG laser and irrigation with conventional syringes, on penetration of Sure Seal Root bioceramic sealer into dentinal tubules. Forty freshly extracted single-rooted human teeth were included in the present in vitro study. All the teeth were prepared up to #40 (4%) with Bio Race rotary file system, using crown-down technique. After chemomechanical preparation, the teeth were randomly assigned to 4 groups based on the agitation protocol: conventional needle irrigation (CNI) with a 30-G needle in a syringe, PUI, Er:YAG laser and XP-Finisher file, Subsequent to the agitation procedure, the root canals were obturated with tapered bioceramic-covered gutta-percha point and, bioceramic sealer, using the single-cone technique. The maximum penetration of the sealer into the dentinal tubules was determined in the coronal, middle and apical thirds using the scanning electron microscope (SEM) technique. After confirmation of the normal distribution of data with Shapiro-Wilk test, Data were analyzed using the one-way ANOVA and Tukey tests. The mean penetration depth of the bioceramic sealer into the dentinal tubules in the PUI group was greater than that of other groups; however, the difference between the two PUI and Er:YAG laser groups in the apical third was not significant (P=0.078). Er:YAG laser, PUI and XP-Finisher file agitation techniques resulted in significantly greater penetration of the bioceramic sealer into the dentinal tubules compared to the CNI (P<0.001). The XP-Finisher file technique in the apical (P=0.752) and middle thirds (P=0.339) and the Er:YAG laser technique in the apical thirds (P=0.086) were not significantly different from the conventional irrigation technique. The PUI technique resulted in significantly deeper penetration of the Bioceramic sealer into the dentinal tubules compared to the three other techniques.

An In Vitro Comparative Evaluation of Distribution of Three Different Sealers by Single-Cone Obturation Technique.

Aim:The aim of this study was to evaluate the distribution of sealer at different levels of the root canal using three different sealers in a single-cone obturation technique.Materials and Methods:Thirty freshly extracted mandibular premolar teeth were selected and access opening was performed. Working length was determined. Cleaning and shaping were done till 25 size K file followed by ProTaper till F2 size. Teeth were then obturated with matching gutta-percha points with the following sealers: Group I, 10 teeth with zinc oxide eugenol sealer; Group II, 10 teeth with AH plus sealer; and Group III, 10 teeth with NanoSeal-S sealer. Teeth were cross sectioned at 3 and 6 mm from the apex. Color photographs of sections were taken at a magnification of ×40 using a camera connected to a stereo-operating microscope and the images were transferred to a computer. Sealer distribution was observed and the canal perimeters coated or uncoated with the sealer can be calculated using a computer digital imaging system.Results:Of the three groups, zinc oxide eugenol showed least sealer distribution. AH Plus and Nanoseal-S showed no significant difference between the distribution at the 3- and 6-mm levels.Conclusion:Both AH Plus and Nanoseal-S showed excellent sealer distribution when compared to zinc oxide eugenol.

Effectiveness of three chemical solutions on gutta-percha cones by rapid sterilization technique: A scanning electron microscope study

Objectives: It is prudent to produce most sterile root canal system and to maximize the most hermetical seal so gutta percha cones are used gutta-percha (GP) cones are used to obliterate the root canal space, prevention of contamination becomes a problem. Hence, the aim of this study was to identify the presence of surface topography, crystallization, and subsequent removal of sodium hypochlorite, glutaraldehyde, and aloe vera crystals on GP cones after rapid sterilization technique – this was a scanning electron microscope (SEM) study. Materials and Methods: GP points of size 80 and 2% taper were divided into four groups depending on the type of agents used for sterilization. Four groups were as follows: Group 1 – control group, Group 2 – aloe vera, Group 3 – glutaraldehyde, and Group 4 – NaOCL. About 10 GP points of each group were immersed for 2 min in different concentrations and observed under SEM to evaluate surface topography and presence of chloride crystals. Statistical analysis was carried out using Chi-square test, Kruskal–Wallis test and Mann–Whitney U-test to compare the results between the groups. All the data were expressed as mean ± standard deviation, and the difference of P Results: Aloe vera found to be an effective medium in decontaminating GP cones compared to glutaraldehyde and NaOCL (sodium hypochlorite). Conclusion: The use of sterile GP cones for the obliteration of root canals is of prime importance, and aloe vera group shows no changes in surface topography and the presence of chloride crystal formation compared to the control group. Hence, it is prudent to produce the most sterile root canal system, maximizing most hermetical seal possible.

Influence of solvent and a supplementary step with a finishing instrument on filling material removal from canals connected by an isthmus.

To evaluate the effectiveness of a solvent (eucalyptol) in improving filling material removal from canals connected by isthmuses, and the additional cleaning effect of a finishing instrument. The mesial canals from 32 mandibular molars (Vertucci's type II morphology) were instrumented and filled with the single-cone technique using Reciproc R25 gutta-percha points (VDW, Munich, Germany) combined with Sealer 26 (Dentsply, Petrópolis, RJ, Brazil). Each root was then subjected to retreatment using the Mtwo instrument system (VDW), with or without a solvent (n=16 per group). The volume of filling material in the canals was assessed by micro-computed tomographic (micro-CT) scans taken before and after retreatment. Canals with remnants of filling material received a supplementary procedure with the XP-endo Finisher R instrument (FKG Dentaire, La Chaux-de-Fonds, Switzerland), with or without eucalyptol, and another micro-CT scan was taken. All retreatment procedures were performed inside a cabinet under a controlled temperature (37°C). Filling material removal was evaluated in the 5-mm apical canal system for the canal+isthmus space or the isthmus alone. Statistical analyses were performed to compare the removal of filling material with and without eucalyptol, and after a supplementary approach with XP-endo Finisher R. The level of significance was set at 5% for all statistical tests (P<0.05). The amount of filling material removed from the canal+isthmus with Mtwo instruments was 83.2% when no solvent was used and 83.8% using the solvent (P>0.05). When the isthmus area was evaluated separately, most specimens were associated with a reduction in the filling material, with no significant difference between the groups with or without using a solvent (P>0.05). The supplementary step with XP-endo Finisher R significantly improved removal of filling material from both canal and isthmus area (P<0.05), regardless of the use of a solvent (P>0.05). The use of eucalyptol did not improve filling material removal from Vertucci's type II molar mesial canals and isthmuses. XP-endo Finisher R significantly enhanced removal of filling material from the canals and isthmuses.

Volume shrinkage mechanism of gutta-percha point studied by differential scanning calorimetry and volume dilatometer in vitro

The mechanism of the volume shrinkage of gutta-percha (GP) point was investigated from the viewpoints of crystalline phase transition of GP and thermal expansion and contraction of thermal-conductive filler. Differential scanning calorimetry (DSC) was employed to calculate the volume shrinkage rate (VSR) of GP point indirectly by determining enthalpy changes that were caused by the crystalline phase transition. Volume dilatometer was utilized to determine the VSR directly to verify the result of DSC. The VSR of GP point calculated by DSC was approximately 2%, which was in good consistence with the result of volume dilatometer tested directly. The volume shrinkage of GP point was driven by two factors, one was the crystalline phase transition of GP that contributed to approximately 99% of the VSR of GP point, and the other was the cold contraction of thermal-conductive filler that could be ignored completely because its contribution rate was only approximately 1%. It was valuable to understand the volume shrinkage behavior of GP point materials and decrease the adverse effect of volume shrinkage in clinical therapy.

Evaluation of the effect of calcium hydroxide and endodontic irrigants on the push-out bond strength of fiber post - an in vitro study.

BackgroundIn recent years, fibre-reinforced composite posts have been proposed for the restoration of root filled teeth as an alternative to pre-fabricated posts or metal dowels.Aims and objectivesThe aim of the study was to analyze the effect of endodontic irrigants used for removal of calcium hydroxide on the push-out bond strength of fiber posts to root canal dentin.MethodsForty human permanent single-rooted mandibular premolars with relatively straight roots were taken and access cavities were prepared and biomechanical preparation done using Rotar Y protaper file till size F2. The samples were divided into Experimental group and Control group. In Experimental groups Intracanal dressing of calcium hydroxide was removed by 2.5% NaOCl and 17% EDTA (Group1), MTAD (Group II) and Qmix (Group III). Control group did not receive Intracanal calcium hydroxide dressing. Canals were obturated using size F2 protaper gutta-percha points and AH plus sealer. After storage for 24 hours, post space was prepared. Forty Tenax fiber post (Coltene) were cemented with Rely X U200 resin. The roots were then transversally sectioned into 3 slices of 1mm thickness corresponding to cervical, middle and apical third. The slices obtained were subjected to micro-push-out bond strength test using a universal testing machine. The data obtained was subjected to statistical analysis using One-Way ANOVA test. P value of .05 was considered as statistically significant level.ResultsThe mean push-out bond strength values for controls, NaOCl/EDTA, MTAD and QMIX group at cervical third were 10.17, 15.84, 20.39 and 20.98 whereas at apical third 4.78, 8.85, 11.66 and 12.10.ConclusionQmix showed higher push-out bond strength values followed by MTAD and NaOCl/EDTA. All the groups showed lowest push-out bond strength values in the apical third followed by middle and the maximum in the cervical region.

Push-Out Bond Strength of Experimental Apatite Calcium Phosphate Based Coated Gutta-Percha.

Objectives To evaluate the push-out bond strength of experimental apatite calcium phosphate coated gutta-percha (HAGP) compared to different commercially available coated gutta-percha root obturation points. Methods Extracted teeth were selected and instrumented using ProTaper rotary files. The canals were assigned into five equal groups and obturated using matching single cone technique as follows: EndoREZ cones and EndoREZ sealer, Bioceramic Endosequence gutta-percha (BCGP) with Endosequence BC sealer, Active GP with Endosequence BC sealer (ActiV GP), conventional GP with Endosequence BC sealer, and HAGP with Endosequence BC sealer. Each root was sectioned transversally at the thickness of 1±0.1 mm to obtain 5 sections (n=25 per group). The specimens were subjected to push-out test using a Universal Test Machine at a loading speed of 0.5 mm/ min. Failure modes after push-out test was examined under stereomicroscope and the push-out data were analyzed using ANOVA and the post hoc Dunnett T3 test (p = 0.05). Results The highest mean bond strength was yielded by HAGP followed by BCGP, ActiV GP, conventional GP, and EndoREZ. There were significant differences between EndoREZ and all other groups (p<0.001). The prominent failure mode of HAGP was mixed mode, whereas EndoREZ exhibited adhesive failure mode. Conventional GP, ActiV GP, and BCGP showed cohesive failure mode. Conclusion HAGP showed promising results to be used as root canal filling material in combination with bioceramic sealer.