Apical Third Of Canal Research Articles

Comparison of calcium hydroxide removal by self-adjusting file, EndoVac, and CanalBrush agitation techniques: An in vitro study

Objectives:This study comparatively evaluated the efficacy of self-adjusting file (SAF), Endovac, and CanalBrush irrigant agitation protocols in removing calcium hydroxide (Ca(OH)2) from the root canals.Materials and Methods:Sixty extracted human mandibular canine teeth were instrumented with ProTaper rotary instruments to size #40 and dressed with Ca(OH)2. The roots were randomly assigned to four groups according to irrigant agitation protocol used (n = 15). In Group 1: Conventional syringe irrigation (no activation, control); Group 2: Rotary brush agitation (CanalBrush); Group 3: Apical negative pressure irrigation (EndoVac system); and Group 4: Sonic agitation (SAF) were used. Scanning electron microscopic (SEM) evaluation was done for assessment of Ca(OH)2 removal in the coronal and apical thirds. Statistical analysis was performed by Wilcoxon and Kruskal-Wallis tests.Results:There were statistically significant differences among the groups (P = 0.218). A statistically significant difference was seen between the test groups in Ca(OH)2 removal from the apical third of the canal (P < 0.05). In the coronal third, there was no difference between the groups (P > 0.05). The most efficient Ca(OH)2 removal in apical third was recorded in Group 3 (EndoVac) and Group 4 (SAF) (P < 0.05). In Group 4 (sonic agitation), there was no significantly difference between Ca(OH)2 removal in coronal and apical thirds.Conclusions:SAF and EndoVac showed significantly better performance than CanalBrush and conventional syringe irrigation in removing Ca(OH)2 from apical third of the root canals.

Effectiveness of ethylenediaminetetraacetic acid (EDTA) and MTAD on debris and smear layer removal using a self-adjusting file

The aim of this study was to investigate the cleaning ability of a self-adjusting file (SAF) system regarding debris and smear layer removal using ethylenediaminetetraacetic acid (EDTA) or MTAD. In total, 45 maxillary incisor teeth were randomly divided into 2 different irrigation groups of 20 canals each and a negative control group of 5 canals. The canals in each of the irrigation groups were irrigated using sodium hypochlorite (1.3%) as an initial irrigant during the first 2 minutes of operation, followed by 2 minutes continuous irrigation with either 17% EDTA or MTAD in a closed system. The negative control group was irrigated using 1.3% sodium hypochlorite. The roots were split longitudinally and subjected to scanning electron microscopy (SEM). The presence of debris and smear layer in the coronal, middle, and apical thirds of the canal was evaluated using a 5-grade scoring system with ×200 and ×2,000 magnification, respectively. The SAF operation with 2-minute continuous irrigation using MTAD resulted in root canal walls that were free of smear layer in 85%, 70%, and 60% and of debris in 95%, 90%, and 95% of the coronal, middle, and apical thirds of the root canals, respectively. The SAF operation with continuous irrigation using EDTA resulted in root canal walls that were free of smear layer in 85%, 60%, and 50% and of debris in 95%, 90%, and 85% of the coronal, middle, and apical thirds of the root canals, respectively. Teeth in the negative control group were totally covered with debris. Evaluation by SEM showed no significant difference between the tested irrigants in removing the smear layer and debris among the different regions of the root canal. Both groups were significantly different from the negative control group. When using the SAF, the protocols used in this study were effective for debridement for all regions of the root canal even for the apical thirds.

Heat transfers to periodontal tissues and gutta-percha during thermoplasticized root canal obturation in a finite element analysis model

The aim of this study was to measure the temperature distributions on the periodontal ligament and apical gutta-percha during thermal obturation with different plugger activation time. The multirooted model of mandibular first molar development and root canal treatment were performed by finite element analysis. The apical thirds of canals were obturated by continuous-wave condensation technique, with 3 seconds and 4 seconds of activation time. The remainder was backfilled with injected gutta-percha in 2 segments (Obtura II). The highest temperatures on the periodontal ligament reached 46.914 degrees C and 48.887 degrees C, in the "dangerous zone" between the root canals, when activation times were 3 seconds and 4 seconds, respectively. The greatest temperature rise within the apical gutta-percha was only 0.859 degrees C. With 3 seconds of activation, the temperature elevation reached almost 47 degrees C, so one should be careful not to extend the activation time beyond 3 seconds, which is clinically difficult to control. The apical gutta-percha temperature was always below the desired level to achieve proper thermoplasticity.

Micro‐CT evaluation of residual material in canals filled with Activ GP or GuttaFlow following removal with NiTi instruments

To assess the efficacy of removing Activ GP or GuttaFlow from canals using NiTi instruments. Root canals in 55 extracted pre-molars were prepared to apical size 40, 0.04 taper. The teeth were imaged with micro-CT, and 30 teeth selected that had consistent apical size and taper of the shaped canals. They were randomly assigned to root filling with either the glass-ionomer-based ActivGP system (n = 15) or the polyvinylsiloxane-based GuttaFlow system (n = 15). After 2 weeks, canals were retreated stepwise with size 40-50 EndoSequence 0.04 taper instruments. Micro-CT scans (8 mum) were taken after use of each instrument to detect root filling residue in the coronal, middle and apical segment, and the retreatment time recorded. Residue, expressed as percentage of canal surface area, was compared between groups with t-tests, and within groups with repeated measures anova and Bonferroni-adjusted pairwise comparisons. Retreatment time was analysed with one-way anova. The percentage of sealer residue-coated canal surface was consistently highest (P < 0.001) in the apical third of canals, and it did not differ significantly between the two root filling groups. Stepwise enlargement from size 40 to 50 significantly decreased the amount of sealer residue in both groups (P < 0.001). Retreatment time did not differ significantly between groups. Both root fillings with ActivGP and GuttaFlow were removed with nickel-titanium rotary instruments. Enlargement of canals up to two sizes beyond the pre-retreatment size was necessary to minimize the amount of sealer remaining.

Calcium hydroxide intracanal dressing removal with different rotary instruments and irrigating solutions: a scanning electron microscopy study

This study evaluated the efficacy of 2 types of rotary instruments employed in association with sodium hypochlorite (NaOCl) or EDTA in removing calcium hydroxide (CH) residues from root canals dentin walls. Forty-two mandibular human incisors were instrumented with the ProTaper System up to F2 instrument, irrigated with 2.5% NaOCl followed by 17% EDTA and filled with a CH intracanal dressing. After 7 days, the CH dressing was removed using 4 techniques: NiTi rotary instrument size 25, 0.06 taper (K3 Endo) and irrigation with 17% EDTA (Group 1), NiTi rotary F1 instrument (ProTaper) and irrigation with 17% EDTA (Group 2), NiTi rotary instrument size 25, 0.06 taper and irrigation with 2.5% NaOCl (Group 3) and NiTi rotary F1 instrument and irrigation with 2.5% NaOCl (Group 4). Two roots without intracanal dressing were used as negative controls. Teeth were evaluated by scanning electron microscopy, in the cervical and apical canal thirds. None of the techniques removed the CH dressing completely. In the apical and cervical thirds, F1 instrument was better than instrument size 25, 0.06 taper in removing CH residues (p<0.05), regardless of the final irrigating solution. No difference was found between the irrigating solutions in the groups of F1 instrument and of instrument size 25, 0.06 taper (p>0.05). The negative controls had no CH residues on the dentin walls. In conclusion, the ProTaper F1 instrument was better than K3 Endo instrument size 25, 0.06 taper in the removal of CH intracanal medication, regardless of irrigating solution used.

A scanning electron microscopic comparison of the cleaning efficacy of endodontic irrigants.

The aim of this study was to compare the cleaning efficacy of three irrigants used during and after instrumentation. Eighty-four single rooted human teeth were randomly divided into 7 groups, 12 cases each, and canals were instrumented with Mtwo rotary systems. 5.25% sodium hypochlorite, Smear Clear and 17% EDTA were used for irrigation of the canal during and/ or after instrumentation. After completion of instrumentation, all canals were dried with paper points and prepared to examine by scanning electron microscope. All SEM photomicrographs were scored at the coronal, middle and apical thirds of canals in each group. The data were statistically analyzed using Mann-Whitney and Kruskal-Wallis tests. In the group irrigated with Smear Clear alone, the coronal thirds of the canals were significantly cleaner than middle thirds (P=0.013) and apical thirds (P=0.028). There were less smear layer in the coronal thirds compared to apical thirds (P=0.047) in the group irrigated with Smear Clear and NaOCl alternately .There were significantly more smear layer in the apical thirds compared to coronal thirds (P<0.001) and middle thirds (P=0.007) in the group that Smear Clear and NaOCl were used as final irrigations. There was not any significant difference between three-thirds of the canals in other groups. Comparison of the all groups showed a statistically significant difference (P<0.001) in the amount of debris and smear layer remaining at all three levels of the canals. The findings of this study suggested that a final rinsing by combination of a chelating agent like EDTA or Smear Clear and NaOCl is necessary to obtain favorable clean wall of root canals.

Removal efficacy of various calcium hydroxide/chlorhexidine medicaments from the root canal

To compare the efficiency of removing calcium hydroxide [Ca(OH)(2)]/chlorhexidine (CHX) (gel), Ca(OH)(2)/CHX (solution) and Ca(OH)(2)/saline pastes with the use of instrumentation and irrigation with sodium hypochlorite and ethylene diamine tetraacetic acid (EDTA) solutions. Moreover the role of the patency file in the cleanliness of the apical third of the root canal was evaluated. Sixty-four human single-rooted teeth with straight canals were used. Root canal preparation was performed with a stepback technique using Hedström (H) files. Teeth were randomly assigned to three groups and subsequently filled with one of the pastes: Ca(OH)(2)/CHX (gel), Ca(OH)(2)/CHX (solution) and Ca(OH)(2)/saline paste. The medicaments were removed 10 days later using instrumentation and irrigation with 1% sodium hypochlorite and 17% EDTA, with or without obtaining patency of the apical foramen with a size 10 H-file. The crowns were removed at the cemento-enamel junction and the roots were grooved longitudinally and split into halves. Images of all halves were acquired with the use of a flatbed scanner. A scoring system of 1 to 4 was used to assess the amount of residue on the cervical, middle and apical third of the canal. Data were subjected to statistical analysis using Kruskal-Wallis and Mann-Whitney tests, with Bonferroni correction, at 95% confidence level (P < 0.05). Remnants of medicament were found in all experimental teeth regardless of the experimental material used and the use of the patency file. When examining the root canal as a whole, Ca(OH)(2)/CHX (gel) paste was associated with significantly larger amount of residue, whereas the Ca(OH)(2)/CHX (solution) paste was associated with less amount (P < 0.05) than the other two medicaments with or without the use of a patency file. None of the techniques used in this study removed the inter-appointment root canal medicaments effectively; the use of the patency file facilitated removal of more of the medicament in the apical third of those straight canals.

Complications associated with fractured file removal using an ultrasonic technique

Perforation was a frequent complication of attempts to remove the file from the apical third of canals.

Preliminary in vitro evaluation of Carisolv as a root canal irrigant.

To test the null hypothesis that Carisolv is no better than PBS in removing organic debris from uninstrumented root canals. The pulps of two uniform groups of 36 immature, sheep mandibular incisors were grossly removed with barbed broaches immediately prior to the study. Roots in group 1 were irrigated with phosphate buffered saline (PBS), strong sodium hypochlorite (4.5%) or Carisolv without ultrasonic agitation, whilst in group 2 the same irrigants were activated with ultrasound. Canal walls were exposed to irrigants for 10, 20 or 30 min at 37 degree C. In group 2, ultrasound was applied for 30 s at 2, 5 and 7 min within each 10 min incubation period. After washing irrigants free and immersion in fixative, all teeth were split longitudinally, critical point dried and sputter coated for SEM analysis. SEM photomicrographs were recorded of representative areas in the coronal, middle and apical canal thirds and debris scored by a single assessor against a five-point scale. Intraobserver reliability was assessed by Cohens kappa scores and debris scores analysed by the non-parametric Kruskal-Wallis test at P < 0.05. Sodium hypochlorite was significantly better than Carisolv and PBS in cleaning root canals (P < 0.0001), whether or not ultrasound was applied. Carisolv was shown to clean canals better than PBS, again whether or not ultrasound was applied (P = 0.01). Both incubation time and ultrasound enhanced the action of Carisolv (P < 0.001) whilst the activity of PBS was not significantly improved by exposure time or the application of ultrasound. Kappa scores of 0.90-0.95 indicated excellent consistency in debris scoring. Within the limitations of this preliminary study (i). Carisolv cleaned root canals better than PBS and shows promise as an adjunct to root canal preparation; (ii). the action of Carisolv was enhanced by incubation times beyond 20 min whether or not ultrasound was applied; (iii). sodium hypochlorite solution remains the gold standard endodontic irrigant, provided that it is used with care and is contained in the canal system.

Endodontic complications of root canal therapy performed by dental students with stainless-steel K-files and Nickel-titanium hand files

Straightening of curved canals is one of the most common procedural errors in endodontic instrumentation. This problem is commonly encountered when dental students perform molar endodontics. The purpose of this study was to compare the effect of the type of instrument used by these students on the extent of straightening and on the incidence of other endodontic procedural errors. Nickel-titanium 0.02 taper hand files were compared with traditional stainless-steel 0.02 taper K-files. Sixty molar teeth comprised of maxillary and mandibular first and second molars were treated by senior dental students. Instrumentation was with either nickel-titanium hand files or stainless-steel K-files. Preoperative and postoperative radiographs of each tooth were taken using an XCP precision instrument with a customized bite block to ensure accurate reproduction of radiographic angulation. The radiographs were scanned and the images stored as TIFF files. By superimposing tracings from the preoperative over the postoperative radiographs, the degree of deviation of the apical third of the root canal filling from the original canal was measured. The presence of other errors, such as strip perforation and instrument breakage, was established by examining the radiographs. In curved canals instrumented by stainless-steel K-files, the average deviation of the apical third of the canals was 14.44 degrees (+/- 10.33 degrees). The deviation was significantly reduced when nickel-titanium hand files were used to an average of 4.39 degrees (+/- 4.53 degrees). The incidence of other procedural errors was also significantly reduced by the use of nickel-titanium hand files.

The effect of the apical dentinal plug on broken endodontic instruments

This study was concerned with the leakage that occurs around broken endodontic instruments when they are left in the apical third of the root canal. Dissociated single-rooted human teeth were used after the crowns were removed. One hundred specimens were prepared by filing and filling according to accepted clinical standards, except that various sizes and styles of instrument segments were intentionally left in the apical third of the canals of 70 specimens. Leakage of these specimens was evaluated by placing them in Ca45 solution, sectioning, and making auto radiograms. Variations in style and size of instruments did not affect the results, but the presence of dentinal debris was highly significant to the leakage results. The scanning electron microscope, was used to investigate the nature of the dentinal debris and how it physically related to the file fragments and dentinal walls. The scanning electron microscope showed that the dentinal debris was not produced by sectioning the segments because the debris was not seen in the canals that were known to be patent. This study was concerned with the leakage that occurs around broken endodontic instruments when they are left in the apical third of the root canal. Dissociated single-rooted human teeth were used after the crowns were removed. One hundred specimens were prepared by filing and filling according to accepted clinical standards, except that various sizes and styles of instrument segments were intentionally left in the apical third of the canals of 70 specimens. Leakage of these specimens was evaluated by placing them in Ca45 solution, sectioning, and making auto radiograms. Variations in style and size of instruments did not affect the results, but the presence of dentinal debris was highly significant to the leakage results. The scanning electron microscope, was used to investigate the nature of the dentinal debris and how it physically related to the file fragments and dentinal walls. The scanning electron microscope showed that the dentinal debris was not produced by sectioning the segments because the debris was not seen in the canals that were known to be patent.