Self-Adjusting File System Research Articles

The efficacy of the self-adjusting file and ProTaper for removal of calcium hydroxide from root canals

The goal of this study was to evaluate the efficacy of the Self-Adjusting File (SAF) and ProTaper for removing calcium hydroxide [Ca(OH)2] from root canals. Thirty-six human mandibular incisors were instrumented with the ProTaper system up to instrument F2 and filled with a Ca(OH)2-based dressing. After 7 days, specimens were distributed in two groups (n=15) according to the method of Ca(OH)2 removal. Group I (SAF) was irrigated with 5 mL of NaOCl and SAF was used for 30 seconds under constant irrigation with 5 mL of NaOCl using the Vatea irrigation device, followed by irrigation with 3 mL of EDTA and 5 mL of NaOCl. Group II (ProTaper) was irrigated with 5 mL of NaOCl, the F2 instrument was used for 30 seconds, followed by irrigation with 5 mL of NaOCl, 3 mL of EDTA, and 5 mL of NaOCl. In 3 teeth Ca(OH)2 was not removed (positive control) and in 3 teeth canals were not filled with Ca(OH)2 (negative control). Teeth were sectioned and prepared for the scanning electron microscopy. The amounts of residual Ca(OH)2 were evaluated in the middle and apical thirds using a 5-score system. None of the techniques completely removed the Ca(OH)2 dressing. No difference was observed between SAF and ProTaper in removing Ca(OH)2 in the middle (P=0.11) and the apical (P=0.23) thirds. The SAF system showed similar efficacy to rotary instrument for removal of Ca(OH)2 from mandibular incisor root canals.

Correlative Bacteriologic and Micro–Computed Tomographic Analysis of Mandibular Molar Mesial Canals Prepared by Self-Adjusting File, Reciproc, and Twisted File Systems

IntroductionThis ex vivo study evaluated the disinfecting and shaping ability of 3 protocols used in the preparation of mesial root canals of mandibular molars by means of correlative bacteriologic and micro–computed tomographic (μμCT) analysis. MethodsThe mesial canals of extracted mandibular molars were contaminated with Enterococcus faecalis for 30 days and assigned to 3 groups based on their anatomic configuration as determined by μCT analysis according to the preparation technique (Self-Adjusting File [ReDent-Nova, Ra’anana, Israel], Reciproc [VDW, Munich, Germany], and Twisted File [SybronEndo, Orange, CA]). In all groups, 2.5% NaOCl was the irrigant. Canal samples were taken before (S1) and after instrumentation (S2), and bacterial quantification was performed using culture. Next, mesial roots were subjected to additional μCT analysis in order to evaluate shaping of the canals. ResultsAll instrumentation protocols promoted a highly significant intracanal bacterial reduction (P < .001). Intergroup quantitative and qualitative comparisons disclosed no significant differences between groups (P > .05). As for shaping, no statistical difference was observed between the techniques regarding the mean percentage of volume increase, the surface area increase, the unprepared surface area, and the relative unprepared surface area (P > .05). Correlative analysis showed no statistically significant relationship between bacterial reduction and the mean percentage increase of the analyzed parameters (P > .05). ConclusionsThe 3 instrumentation systems have similar disinfecting and shaping performance in the preparation of mesial canals of mandibular molars.

Micro–computed Tomography Study of Oval-shaped Canals Prepared with the Self-adjusting File, Reciproc, WaveOne, and ProTaper Universal Systems

IntroductionThe newly developed single-file systems claimed to be able to prepare the root canal space with only 1 instrument. The present study was designed to test the null hypothesis that there is no significant difference in the preparation of oval-shaped root canals using single- or multiple-file systems. MethodsSeventy-two single-rooted mandibular canines were matched based on similar morphologic dimensions of the root canal achieved in a micro–computed tomographic evaluation and assigned to 1 of 4 experimental groups (n = 18) according to the preparation technique (ie, Self-Adjusting File [ReDent-Nova, Ra’anana, Israel], WaveOne [Dentsply Maillefer, Ballaigues, Switzerland], Reciproc [VDW, Munich, Germany], and ProTaper Universal [Dentsply Maillefer] systems). Changes in the 2- and 3-dimensional geometric parameters were compared with preoperative values using analysis of variance and the post hoc Tukey test between groups and the paired sample t test within groups (α = 0.05). ResultsPreparation significantly increased the analyzed parameters; the outline of the canals was larger and showed a smooth taper in all groups. Untouched areas occurred mainly on the lingual side of the middle third of the canal. Overall, a comparison between groups revealed that SAF presented the lowest, whereas WaveOne and ProTaper Universal showed the highest mean increase in most of the analyzed parameters (P < .05). ConclusionsAll systems performed similarly in terms of the amount of touched dentin walls. Neither technique was capable of completely preparing the oval-shaped root canals.

Efficacy of self-adjusting file and passive ultrasonic irrigation on removing calcium hydroxide from root canals

The aim of this study was to evaluate the efficiencies of the self-adjusting file (SAF) system, passive ultrasonic irrigation (PUI), and conventional irrigation (CI) in removing calcium hydroxide (CH) from root canals. Fifty-one mandibular premolars were used. After root canals were instrumented and filled with a CH paste, 45 teeth were randomly assigned to three experimental groups according to CH removal technique: SAF system, PUI, or CI. The remaining 6 teeth served as positive and negative controls. All samples were evaluated by scanning electron microscopy (SEM) and scored. None of the techniques removed CH completely. However, results at coronal, middle and apical thirds showed that PUI technique was significantly more effective than SAF and CI in removing CH dressing residues from root canal walls.

Effectiveness of the self-adjusting file versus ProTaper systems to remove the smear layer in artificially induced internal root resorption cavities

Aim: Smear layer removal from artificially prepared internal root resorption (IRR) cavities using the self-adjusting file (SAF) system with activated continuous irrigation or the ProTaper system (Dentsply Maillefer, Ballaigues, Switzerland) with conventional syringe/needle irrigation was compared. Materials and methods: Twenty-eight maxillary central incisors were selected, decoronated and 20 of them were randomizedly splited along the coronal plane into labial and lingual sections, and artificial IRR cavities were prepared in both walls. Tooth segments were rejoined and teeth were divided into two groups. Each group (n = 10) was prepared using the SAF or ProTaper system with 12-mL 5.25% NaOCl and 12-mL 17% EDTA. Root canals were prepared in six intact positive control teeth using the SAF or ProTaper system with 5.25% NaOCl and 17% EDTA. As negative controls, two intact teeth were prepared using NaOCl only. Roots were than split longitudinally from the rejoined segments and samples were evaluated under scanning electron microscopy using a five-point scoring system. Results: Most SAF (87%) and ProTaper (83%) samples (P > 0.05), had scores of 1 and 2 indicating clean canal walls for the IRR cavities. Conclusions: SAF with activated continuous irrigation and ProTaper with conventional syringe/needle irrigation both successfully removed the smear layer from artificially prepared IRR cavities

The efficacy of the self-adjusting file and ProTaper for removal of calcium hydroxide from root canals

ObjectiveThe goal of this study was to evaluate the efficacy of the Self-Adjusting File (SAF) and ProTaper for removing calcium hydroxide [Ca(OH)2] from root canals. Material and MethodsThirty-six human mandibular incisors were instrumented with the ProTaper system up to instrument F2 and filled with a Ca(OH)2-based dressing. After 7 days, specimens were distributed in two groups (n=15) according to the method of Ca(OH)2 removal. Group I (SAF) was irrigated with 5 mL of NaOCl and SAF was used for 30 seconds under constant irrigation with 5 mL of NaOCl using the Vatea irrigation device, followed by irrigation with 3 mL of EDTA and 5 mL of NaOCl. Group II (ProTaper) was irrigated with 5 mL of NaOCl, the F2 instrument was used for 30 seconds, followed by irrigation with 5 mL of NaOCl, 3 mL of EDTA, and 5 mL of NaOCl. In 3 teeth Ca(OH)2 was not removed (positive control) and in 3 teeth canals were not filled with Ca(OH)2 (negative control). Teeth were sectioned and prepared for the scanning electron microscopy. The amounts of residual Ca(OH)2 were evaluated in the middle and apical thirds using a 5-score system. ResultsNone of the techniques completely removed the Ca(OH)2 dressing. No difference was observed between SAF and ProTaper in removing Ca(OH)2 in the middle (P=0.11) and the apical (P=0.23) thirds. ConclusionThe SAF system showed similar efficacy to rotary instrument for removal of Ca(OH)2 from mandibular incisor root canals.

Comparison of the Cleaning Efficacy of Self-Adjusting File and Rotary Systems in the Apical Third of Oval-shaped Canals

IntroductionCleaning and shaping of root canals are essential steps for the success of endodontic therapy. The purpose of this study was to evaluate the tissue debridement efficacy of the self-adjusting file (SAF) protocol in the apical third of oval-shaped canals of mandibular incisors in comparison with a nickel-titanium rotary system preparation. MethodsTwenty-six single-rooted human mandibular incisor teeth were selected and assigned to a control (n = 4) and 2 experimental groups (n = 11) according to 1 of 2 instrumentation techniques, SAF and nickel-titanium rotary systems. After root canal preparation, the apical thirds of the specimens were submitted to histologic processing and analyzed by optical microscopy regarding the percentage of debris and uninstrumented root canal walls. The data were statistically compared by using unpaired t test with Welch's correction, and the level of significance was set at 5%. ResultsThe percentage of remaining debris and uninstrumented canal perimeter was significantly lower in SAF group (2.18 ± 2.71 and 12.33 ± 7.85, respectively) than in rotary group (13.11 ± 12.98 and 53.54 ± 15.95, respectively) (P < .05). In the SAF group most of specimens were completely free of debris, whereas in the rotary group 53% of the canals presented debris. ConclusionsSAF had significantly more contact to the dentin walls and removed more debris than rotary instrumentation in the apical third of mandibular incisors.

Self-Adjusting File Cleaning-Shaping-Irrigation System Improves Root-filling Bond Strength

IntroductionThe aim of the present study was to assess the bond strength of root fillings in oval-shaped canals prepared with the self-adjusting file (SAF) system. MethodsA careful specimen selection resulted in 2 equal groups, each consisting of 12 extracted mandibular canines with oval canals that had vital pulps before extraction. One group was subjected to the SAF protocol, and the other group underwent conventional protocol, which was the ProTaper system with syringe-needle irrigation. Full-strength sodium hypochlorite was used as an irrigant for both groups. The teeth were obturated in a standardized way, filled with a lentulo spiral as the root filling, and then prepared for micropush-out assessment by using root slices of 1-mm thickness. Loading was performed on a universal testing machine at a speed of 0.5 mm/min−1. The Student's t test for pairwise comparisons was applied to assess the effect of each preparation technique on the push-out bond strength. ResultsAll specimens showed measurable adhesive properties to root dentin. In addition, no premature failure occurred. The group-by-location interaction was significant (P = .0071); thus, the group comparisons were dependent on the canal third. Overall, the push-out bond strength was the highest in the coronal third and the lowest in the apical third. SAF-prepared specimens displayed significantly higher bond strengths (P = .0012, 0.51–5.9 MPa). ConclusionsThe present study showed that SAF preparation markedly influenced root-filling push-out bond strength in oval-shaped canals. Further investigations are needed to provide a better understanding of the physicochemical modifications of the root dentin prepared with the SAF cleaning-shaping-irrigation system.

In Vitro Canal and Isthmus Debris Removal of the Self-Adjusting File, K3, and WaveOne Files in the Mesial Root of Human Mandibular Molars

IntroductionThe purpose of this study was to compare the effectiveness of debris removal between the Self-Adjusting File (SAF), WaveOne, and K3 file systems in the mesial roots of mandibular molars. In addition, the SAF was tested as a potential adjunct after instrumentation with other systems. MethodsThe mesial roots of 30 extracted mandibular molars were mounted in resin by using the K-Kube, sectioned at 2 and 4 mm from working length, and randomly placed into 3 groups: K3 group, sequential preparation with K3 files to an apical size of 35/.04; WaveOne group, preparation with WaveOne primary file; and SAF group, preparation with SAF. Images were taken before instrumentation, after instrumentation, after final irrigation, and after SAF adjunct irrigation. A cleanliness percentage was calculated by using interactive software. Comparisons between groups were analyzed with repeated-measures analysis of variance and post hoc tests (P < .05). ResultsThere was no significant difference in canal cleanliness among the groups, but the WaveOne was significantly worse for isthmus cleanliness. Use of the SAF as an adjunct only significantly improved canal cleanliness in the K3 group at the 2-mm level by an average of 1.7%. ConclusionsThere was no difference in canal cleanliness between the 3 file systems; however, the SAF and K3 files performed significantly better than the WaveOne with respect to isthmus cleanliness. When used as a final irrigation adjunct device after instrumentation, the SAF provided a significant improvement only in a subset of the K3 group.

Self-Adjusting File Cleaning-Shaping-Irrigation System Optimizes the Filling of Oval-shaped Canals with Thermoplasticized Gutta-percha

IntroductionThis study aimed to compare the filling ability of carrier-based thermoplasticized gutta-percha in flat-oval canals prepared using either rotary ProTaper files (Dentsply Maillefer, Ballaigues, Switzerland) or the Self-Adjusting File system (SAF) (ReDent-Nova, Ra'anana, Israel). MethodsThirteen pairs of mandibular incisors were selected from a random collection. The teeth in each pair had single root canals with a flat-oval cross-section and similar sizes and dimensions. Teeth from each pair were randomly assigned to 1 of 2 experimental groups. One group was instrumented using the ProTaper NiTi system, whereas the SAF system was used in the other. Root filling was performed with Thermafil obturators (Dentsply Tulsa Dental Products, Tulsa, OK), and teeth were sectioned at 6, 5, 4, and 3 mm from the apex; the cut surface was subjected to morphometric measurement to establish the percent gutta-percha–filled area (PGFA) for each section. The Wilcoxon matched-pairs signed rank test was used to assess the effect of the 2 preparation methods on the PGFA. ResultsThe median PGFA in the ProTaper group was 77.5%, whereas the median PGFA was 90.5% in the SAF group (P < .05). In the SAF-instrumented group, 17.8% of the specimens had a PGFA ≥95% compared with only 5.8% of the ProTaper-instrumented specimens (P < .05). ConclusionsInstrumentation of the flat-oval canals with the SAF system led to a significantly higher PGFA compared with ProTaper instrumentation with syringe and needle irrigation.

Efficacy of irrigation systems on penetration of sodium hypochlorite to working length and to simulated uninstrumented areas in oval shaped root canals

To assess the ability of sodium hypochlorite (NaOCl) to penetrate simulated lateral canals and to reach working length (WL) when using the self-adjusting file (SAF). Seventy single-rooted teeth with oval-shaped canals were used. Upon access, presence of a single canal was confirmed by direct visualization under a dental-operating microscope. Canal length and patency were obtained using a size 10 K-file and root length standardized to 18 mm. Pre-enlargement was restricted to the coronal one-third. The apical size of each canal was gauged at WL and samples larger than size 30 were excluded. Canals were instrumented for 5 min using the SAF system while delivering a total of 20 mL of 5.25% NaOCl and 5 mL of 17% EDTA. Then, the apical diameters were standardized to size 35 using hand files. Four hundred and twenty simulated lateral canals were then created during the clearing process and roots coated with wax to create a closed system. All samples were then cleared and randomly assigned to four experimental groups: 1 (n = 15) positive pressure; 2 (n = 15) SAF without pecking motion; 3 (n = 15) SAF with pecking motion; 4 (n = 15) apical negative pressure (ANP) irrigation and (n = 10) control groups. Samples were scored on the basis of the ability of the contrast solution to reach WL and permeate into the simulated lateral canals to at least 50% of the total length. The Kruskal-Wallis test was used to analyse irrigant penetration and the Tukey test to determine statistical differences between groups (P < 0.05). All samples irrigated with ANP were associated with irrigant penetration to WL (Table 1). The differences between group 4 (ANP) and all other groups were significant in penetration to WL (P < 0.05). The pecking motion allowed for further penetration of the irrigant when using the SAF system but failed to irrigate at WL. None of the experimental groups demonstrated predictable irrigation of simulated lateral canals. In this laboratory model, ANP was the only delivery system capable of irrigating consistently to full WL. None of the systems tested produced complete irrigation in artificial lateral canals.

Hard‐tissue debris accumulation created by conventional rotary versus self‐adjusting file instrumentation in mesial root canal systems of mandibular molars

To evaluate the accumulation of hard-tissue debris when using the Self-adjusting File (SAF) system in mesial roots of mandibular molars with isthmuses and to compare it with that occurring when the ProTaper file system was used. Forty extracted human mandibular molars with joining mesial root canals and an isthmus between the two canals were randomly assigned to two experimental groups and scanned using micro-computed tomography. Root canals in the control group (N = 20) were instrumented using the ProTaper rotary system until F3. Irrigation with 1 mL of 3% NaOCl solution was applied after each instrument. Root canals in the experimental group (N = 20) were prepared using the SAF for 4 min, with continuous irrigation (3% NaOCl, 4 mL min(-1)). After rescanning, canals in both groups were further irrigated with 5 mL of 17% EDTA for 2 min. After final scanning, the per cent value of total canal system volume filled with hard-tissue debris was calculated. Statistical analysis was performed using Mann-Whitney U-test; the alpha-type error was set at 1%. Instrumentation of the root canals with ProTaper left 10.1% (IQR 5.2) of the total canal system volume filled with hard-tissue debris while preparation with the SAF left 1.7% (IQR 1.6). This difference was highly significant (P < 0.0001). After subsequent EDTA irrigation, these values were significantly reduced (P < 0.01) to 7.9% (IQR 4.1) and 1.3% (IQR 0.8) in the ProTaper and SAF groups, respectively. Preparation with the SAF system resulted in less hard-tissue debris accumulation in isthmus-containing root canal systems compared with instrumentation with ProTaper rotary files.

Efficacy of the Self-Adjusting File System on Cleaning and Shaping Oval Canals: A Microbiological and Microscopic Evaluation

Introduction The shaping ability of root canal instruments is determined by a complex interrelationship of parameters such as cross-sectional design and the ability to remove debris and the smear layer. The self-adjusting file (SAF) consists of a hollow, flexible instrument in the form of a compressible, thin-walled, pointed cylinder. The aim of this study was to compare the SAF with the ProTaper rotary file system, evaluating debris and smear layer removal and the presence of bacteria by using microbiological and scanning electron microscopy (SEM) evaluation. Methods Fifty maxillary premolars were inoculated with Enterococcus faecalis for 30 days and then randomly distributed into 2 groups. Group 1 was prepared with ProTaper rotary instruments and irrigated with 30-gauge side-vented needles. Group 2 was prepared by using the SAF system with continuous irrigation. Bacteriologic samples were taken before and after preparation. All samples were then longitudinally split and analyzed under scanning electron microscopy. The scoring was carried out by 3 blinded evaluators. Results In group 1, 40% of samples had negative cultures with postinstrumentation samples taken with paper points (S2a) and 45% with postinstrumentation dentin samples (S2b). In group 2, 20% of samples had negative cultures with S2a and 15% with S2b. Intragroup analyses evaluating the reduction in the number of colony-forming units (CFUs) from S1 to S2a and S2b demonstrated both preparation techniques were highly effective ( P < .01). Further reduction of CFUs was observed when comparing S2a and S2b in group 1 ( P < .05), whereas no difference was observed in group 2. Intergroup analysis demonstrated a statistically significant difference of CFUs at S2a and S2b ( P < .05). SEM scores were consistent with the microbiology findings. Conclusions The SAF system does not allow control of the apical enlargement, thus limiting the ability of the irrigants to achieve effective and predictable disinfection.

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.

Time-dependent Antibacterial Effects of the Self-Adjusting File Used with Two Sodium Hypochlorite Concentrations

Introduction This in vitro study evaluated the time-dependent ability of the self-adjusting file (SAF) used with either of two NaOCl concentrations to reduce bacterial populations in long oval root canals. Methods Oval-shaped canals from extracted teeth were infected with Enterococcus faecalis for 30 days and subjected to preparation with the SAF system using continuous irrigation with either 2.5% NaOCl (n = 11) or 6% NaOCl (n = 11). Bacteriological samples were taken before preparation (baseline) and after 2, 4, and 6 minutes of SAF operation. Results Intragroup quantitative analyses revealed that the SAF operating for 2, 4, or 6 minutes yielded a highly significant bacterial reduction when compared with counts at baseline ( P < .001) irrespective of the NaOCl concentration. No significant differences were found for intragroup analyses comparing the three time periods ( P > .05). Likewise, intergroup quantitative analysis showed no significant difference for the SAF with 2.5% NaOCl or 6% NaOCl during 2, 4, or 6 minutes ( P > .05). The incidence of positive cultures in the 2.5% NaOCl group was 6 of 11, 5 of 11, and 2 of 11 after 2, 4, and 6 minutes, respectively. Corresponding figures in the 6% NaOCl group were 4 of 11, 2 of 11, and 1 of 11. When all samples were gathered together, overall findings revealed that using the SAF for 6 minutes significantly reduced both the bacterial counts ( P = .02) and the incidence of positive cultures ( P = .04) when compared with 2 minutes. Conclusions Findings revealed that the SAF promoted a significant reduction in bacterial populations even after only 2 minutes regardless of the NaOCl concentration. The most impressive results were obtained after a 6-minute operation.

Eight Months of Clinical Experience with the Self-Adjusting File System

Introduction The Self-Adjusting File (SAF) system (ReDent-Nova, Ra'anana, Israel) has been recently introduced for the simultaneous instrumentation and irrigation of root canals. The SAF is claimed to adapt itself three dimensionally to the root canal, including its cross-section. It is operated with a continuous flow of sodium hypochlorite that is delivered into the root canal through the hollow file and claimed to be activated by sonic agitation of the irrigant. Our aim was to present for the first time clinical cases prepared with the SAF system and to describe a clinical classification of canals, according to their difficulty, with recommendations for endodontic treatment sequences for each category. Methods This report is based on the experience of a single endodontist, who used the system to treat more than 50 consecutive primary endodontic cases over the prior 8 months. Results A clinical classification was developed which enabled the operator to select a treatment protocol for easy and optimal glide path preparation to be effectively used with the SAF file in the various root canals encountered in the clinical environment. Conclusions Clinical classification of canal difficulty makes root canal treatment sequences with the SAF simple and predictable. Many types of cases can be treated with the SAF system although a novice user is advised to advance slowly along the learning curve from simpler to more complicated canals.

The Self-Adjusting File Optimizes Debridement Quality in Oval-shaped Root Canals

Introduction Oval-shaped canals represent a challenge for rotary nickel-titanium (NiTi) files because buccal and/or lingual recesses are commonly left uninstrumented. The aim of the present study was to evaluate the debridement quality of the Self-Adjusting File (SAF) system in oval canals and compare it with the debridement achieved by a commonly used NiTi rotary system. Methods A careful specimen selection resulted in two equal groups each consisting of 12 extracted mandibular canines with oval canals that had vital pulps before extraction. All canals had a buccolingual diameter that was at least 2.5 times larger than that of the mesiodistal one as defined from radiographs. One group was subjected to the SAF protocol, whereas the other group underwent conventional protocol; the ProTaper system up to the F2 instrument was used with syringe and open end needle irrigation. Sodium hypochlorite (5.25%) was used as an irrigant for both groups. The roots were then histologically processed and 0.6-μm-thick cross-sections were obtained every 0.5 mm from the 1- to 5-mm apical levels. Morphometric evaluation was performed on cross-sections to determine the amount of remaining pulp tissue as a percent of the root canal area. Results The group-by-location interaction was not significant ( P > .05), which means that the group comparisons were not dependent on the cross-sectional level. There was significantly greater residual pulp tissue left after ProTaper system instrumentation versus SAF instrumentation (21.4% vs 9.3%, P < .05). Conclusions The SAF protocol was significantly more efficient for debridement of oval root canals than the rotary ProTaper protocol.

Ability of Chemomechanical Preparation with Either Rotary Instruments or Self-adjusting File to Disinfect Oval-shaped Root Canals

Introduction Oval-shaped root canals might represent a great challenge for proper disinfection. This study compared the capability of a newly developed instrument, the self-adjusting file (SAF), and rotary nickel-titanium (NiTi) instrumentation to eliminate Enterococcus faecalis populations from long oval root canals of extracted human teeth. As a secondary purpose, the ability of a modification in sampling technique to recover bacteria lodged in recesses of oval canals was evaluated. Methods Long oval canals from mandibular incisors and maxillary second premolars were infected with E. faecalis (ATCC 29212) for 30 days and then randomly distributed into 2 experimental groups. In group 1, canals were prepared up to a 40/04 rotary BioRaCe instrument by using irrigation with NaviTip needles; in group 2, canals were prepared by using the SAF system with continuous irrigation. NaOCl and ethylenediaminetetraacetic acid were used as irrigants. Bacteriologic samples were taken before (S1) and after preparation (S2a and S2b). Results Reduction in the bacterial populations was highly significant in both groups ( P < .001). Preparation of long oval canals with the SAF was significantly more effective than rotary NiTi instrumentation in reducing intracanal E. faecalis counts ( P = .01). Frequency of positive cultures in S2 samples was 11 of 20 (55%) for rotary instrumentation and 4 of 20 (20%) for SAF instrumentation ( P = .048). S2b samples (modified method) yielded more positive samples than S2a (12/40 vs 5/40), but this difference reached no statistical significance ( P > .05). Conclusions The SAF system was significantly more effective than rotary NiTi instrumentation used with syringe/needle irrigation in disinfecting long oval root canals in vitro. A modified sampling technique might be necessary for oval canals.

The Self-adjusting File (SAF). Part 3: Removal of Debris and Smear Layer—A Scanning Electron Microscope Study

AimThe aim of this study was to evaluate the cleaning ability of the Self-Adjusting File (SAF) system in terms of removal of debris and smear layer. MethodologyRoot canal preparations were performed in 20 root canals using an SAF operated with a continuous irrigation device. The glide path was initially established using a size 20 K-file followed by the SAF file that was operated in the root canal via a vibrating motion for a total of 4 minutes. Sodium hypochlorite (3%) and EDTA (17%) were used as continuous irrigants and were alternated every minute during this initial 4-minute period. This was followed by a 30-second rinse using EDTA applied through a nonactivated SAF and a final flush with sodium hypochlorite. The roots were split longitudinally and subjected to scanning electron microscopy (SEM). The presence of debris and a smear layer in the coronal, middle, and apical thirds of the canal were evaluated through the analysis of the SEM images using five-score evaluation systems based on reference photographs. ResultsThe SAF operation with continuous irrigation, using alternating irrigants, resulted in root canal walls that were free of debris in all thirds of the canal in all (100%) of the samples. In addition, smear layer–free surfaces were observed in 100% and 80% of the coronal and middle thirds of the canal, respectively. In the apical third of the canal, smear layer–free surfaces were found in 65% of the root canals. ConclusionsThe operation of the SAF system with continuous irrigation coupled with alternating sodium hypochlorite and EDTA treatment resulted in a clean and mostly smear layer–free dentinal surface in all parts of the root canal.