ProTaper Rotary System Research Articles

Efficacy of 2 Reciprocating Systems Compared with a Rotary Retreatment System for Gutta-percha Removal

IntroductionThe maximum removal of root canal filling material is essential for successful endodontic retreatment. The purpose of this study was to assess the efficacy of 2 reciprocating systems (Reciproc [VDW, Munich, Germany] and WaveOne [Dentsply Maillefer, Ballaigues, Switzerland]) compared with a nickel-titanium (NiTi) rotary system (ProTaper Universal Retreatment [Dentsply Maillefer]) in the removal of root canal filling material. MethodsSixty root canals of extracted human maxillary incisors were prepared using the NiTi ProTaper rotary system with the complementary use of a #40 K-type file and then obturated. The specimens were divided into 3 groups (n = 20) according to the system used for filling removal: group 1: instrument R25 of the Reciproc system, group 2: primary instrument of the WaveOne system, and group 3: NiTi rotary instruments of the ProTaper Universal Retreatment system. The teeth were cleaved longitudinally and photographed under a dental operating microscope with 5 × magnification. Images were transferred to a computer, and residual filling material was quantified using Image Tool software (University of Texas Health Science Center, San Antonio, TX). Results were compared using 1-way analysis of variance (P < .05). ResultsAll teeth examined had filling remnants within the canal. No statistically significant difference (P > .05) in residual filling material was observed among the groups, with 4.30% in group 1, 2.98% in group 2, and 3.14% in group 3. ConclusionsThe Reciproc and WaveOne reciprocating systems were as effective as the ProTaper Universal retreatment system for gutta-percha and sealer removal.

Mineral Trioxide Aggregate Mixed with Normal Saline, Calcium Chloride or KY Jelly as Apical Plug in Simulated Open Apices: An In vitro Microleakage Study.

Mineral trioxide aggregate (MTA) mixed with normal saline has short working time, delayed setting time, and poor consistency when used as an apical plug. A preliminary study suggested that substituting normal saline with KY Jelly or 5% calcium chloride (CaCl2) as a vehicle expedites the setting time of MTA. The present in vitro study compared the microleakage of ProRoot MTA mixed with normal saline (MS) to that of ProRoot MTA mixed with KY Jelly and/or 5% CaCl2 in simulated canals with open apices. Thirty six single-rooted extracted human teeth were cleaned and shaped with ProTaper rotary system to make 36 standardized artificially created open apices. Teeth were randomly divided into three experimental groups (n=10) and two control groups (n=3). In group 1, MTA was mixed with normal saline (MS) and placed into the canals to form 4 to 5 mm apical plugs. In group 2, MTA was mixed with 5% CaCl2 (MC) and in group 3, MTA was mixed with KY Jelly (MK). The other two groups served as positive and negative controls. The remaining canal spaces in the experimental groups were backfilled with thermoplasticized gutta-percha without sealer. Dye penetration and clearing was used to evaluate the sealing ability of each group. The samples were then examined under stereomicroscope to measure the microleakage of different MTA mixtures in mm. Data were statistically analyzed using One-Sample Kolmogorov-Smirnov test for determination of normal distribution and then by one-way ANOVA and Tukey's tests to detect any significance. Positive and negative controls responded as expected. The MS group showed the least mean dye penetration value. There was a significant difference between MS with other groups (P<0.05) but no difference was found between MC and MK groups. Within the limitations of this in vitro study, we can conclude that among these three vehicles, normal saline mixed with ProRoot MTA has the least amount of microleakage in canals with open apices.

Fracture Strength of Roots Instrumented with Self-Adjusting File and the ProTaper Rotary Systems

IntroductionThe purpose of this study was to evaluate the fracture strength of roots instrumented with the Self-Adjusting File (SAF; ReDent-Nova, Ra’anana, Israel) and the ProTaper system (Dentsply Maillefer, Ballaigues, Switzerland) and filled with the cold lateral compaction technique. MethodsIn total, 50 mandibular premolar teeth were sectioned at or below the cementoenamel junction to obtain roots 13 mm in length. The roots were balanced with respect to buccolingual-mesiodistal diameters and weight. They were distributed into 4 experimental groups and 1 control group (n = 10): no instrumentation (control group), instrumentation with ProTaper rotary files but no filling (PT), instrumentation with ProTaper rotary files and filling with cold lateral compaction (PT filling), instrumentation with SAF but no filling (SAF), and instrumentation with SAF and filling with cold lateral compaction (SAF filling). AH Plus sealer (Dentsply DeTrey, Konstanz, Germany) was used along with gutta-percha points. One week later, a vertical load was applied to the specimen’s canal until fracture occurred. Data were statistically analyzed using 1-way analysis of variance (P = .05). ResultsThe mean fracture load was 244 ± 51 N for the control group, 226 ± 21 N for the PT, 242 ± 45 N for PT filling, 233 ± 14 N for the SAF, and 271 ± 44 N for SAF filling. However, the differences were not statistically significant (P > .05). ConclusionsInstrumentation with the SAF or the ProTaper rotary system did not change the fracture strength of standardized roots with respect to cross-sectional diameter and weight.

Effect of Patency File on Transportation and Curve Straightening in Canal Preparation with ProTaper System

The aim of this ex vivo study was to evaluate the effect of using a patency file on apical transportation and curve straightening during canal instrumentation with the ProTaper rotary system. Seventy permanent mandibular first molars with mesiobuccal canals, measuring 18–23 mm in length and with a 25–40° curvature (according to the Schneider method), were selected. The working lengths were determined and the teeth were mounted and divided into two experimental groups: (A) prepared by the ProTaper system without using a patency file (n = 35) and (B) prepared by the ProTaper system using a patency file (n = 35). Radiographs taken before and after the preparation were imported into Photoshop software and the apical transportation, and curve straightening were measured. Data were analyzed using independent t-test. Partial correlation analysis was performed to evaluate the relationship between the initial curvature, transportation, and curve straightening (α = 0.05). Using a patency file during canal preparation significantly decreased both apical transportation and curve straightening (P < 0.001). There were significant relationships between the angle of curvature, transportation and curve straightening in pairs (P < 0.001). Apical patency is recommended during root canal preparation with the ProTaper rotary system.

Effect of Photoactivated Disinfection on Bond Strength of Root Canal Filling

IntroductionThe aim of this in vitro study was to assess and compare the effect of photoactivated disinfection (PAD) on the bond strength of root canal sealers to human root canal dentin using the push-out test. MethodsFifteen extracted human mandibular premolar teeth with single and straight roots were used. After the clinical crowns were removed from the cementoenamel junction, root canals were prepared with the ProTaper (Dentsply Maillefer, Ballaigues, Switzerland) rotary system to the size of the F3 file. The smear layer of the roots was removed using 17% EDTA followed by 5.25% sodium hypochlorite (NaOCl) and distillate water. The roots were then randomly divided into 3 groups (n = 5) according to the final irrigation regimen. In group 1, PAD (FotoSan; CMS Dental, Copenhagen, Denmark) was applied to the root canals and light cured for 20 seconds. Group 2 was finally irrigated with a 2% solution of chlorhexidine gluconate, and group 3 served as the control group (NaOCl + EDTA). All the canals were then obturated with the lateral condensation technique using gutta-percha and AH Plus sealer (Dentsply Maillefer) sealer. One-millimeter-thick horizontal sections from the coronal and midthirds of each root (n: 5 × 4 = 20) were sliced for the push-out bond strength measurement. The data were converted to megapascals and statistically analyzed using 1-way analysis of variance and the post hoc Tukey test. ResultsThere was no significant difference among the bond strength of PAD, chlorhexidine gluconate, and NaOCl (P > .05). ConclusionsWe conclude that PAD does not adversely affect the bond strength of the AH Plus sealer to root canal dentin and that it can be used for the final disinfection of root canals.

Effect of passive ultrasonic irrigation and manual dynamic irrigation on smear layer removal from root canals in a closed apex in vitro model

To compare the effect of passive ultrasonic irrigation with manual dynamic irrigation on smear layer removal from root canals using a closed apex in vitro model. The root canals of 45 freshly-extracted human single-rooted mandibular premolar teeth were prepared by the Pro-Taper rotary system to an apical preparation of F4 size. Prepared teeth were randomly divided into three groups; two experimental groups and one control group (n=15) on the basis of the type of activation of final irrigation as follows: (a) Group A, 3% sodium hypochlorite (NaOCl) and 17% ethylenediaminetetraacetic acid (EDTA), no activation received; (b) Group B, 3% NaOCl and 17% EDTA, ultrasonic activation with a small file; and (c) Group C, 3% NaOCl and 17% EDTA, manual activation with a master gutta-percha point. The prepared teeth were decoronated and split into two halves longitudinally, and observed under a scanning electron microscope to assess the removal of the smear layer. In the apical-third region, the mean smear scores for groups B and C were significantly less than those of Group A (control group) (P<0.05). Both activation techniques are important adjuncts in removing the smear layer, with manual dynamic activation being a simpler, safer, and more cost-effective technique.

Comparison of irrigant penetration up to working length and into simulated lateral canals using various irrigating techniques

To evaluate the effect of an apical negative pressure system, a passive ultrasonic irrigation system and a combination of both apical negative pressure and passive ultrasonic irrigation on the penetration of the irrigating contrast solution (ICS) up to working length and into simulated lateral canals. The root canals of 64 single-rooted teeth were instrumented using the ProTaper rotary system. In each sample, three simulated lateral canals were created at 2, 4 and 6mm levels from the root apex using a 06-size C+ file (Dentsply Maillefer, Ballaigues, Switzerland). Samples were randomly assigned into 4 experimental groups (n=16): group I - conventional needle irrigation, group II - passive ultrasonic irrigation, group III - apical negative irrigation system and group IV - combination of passive ultrasonic irrigation and apical negative pressure irrigation system. To examine irrigating solution penetration, Indian ink was mixed with 5.25% NaOCl and delivered into the root canals. Samples were then assessed by direct observation of the images taken using Canon EOS rebel T3. The depth of penetration of ICS up to the working length and into the simulated lateral canals was analysed using chi-squared tests. The combination (ANP and PUI) and ANP group had significantly deeper ICS penetration up to the working length (P<0.001). The combination (ANP and PUI) and the PUI group exhibited significantly greater ICS penetration into lateral canals at the 6mm level (P<0.001). At the 4 and 2mm levels, the combination of ANP and PUI had significantly greater ICS penetration into the lateral canals than the other groups (P<0.001). The combination of ANP and PUI was the only group able to achieve irrigating contrast solution penetration both up to the working length and into lateral canals.

Quantitative evaluation of apical extrusion of intracanal bacteria using K3, Mtwo, RaCe and protaper rotary systems: An in vitro study

Aim:This aim of this study was to evaluate the number of bacteria extruded apically during root canal preparation using Four Rotary instrumentation techniques.Materials and Methods:A total of 50 extracted mandibular premolars were selected, access cavities prepared and inserted in to rubber stoppers of 10 mL glass vial. Root canals were contaminated with a suspension of Enterococcus faecalis (E. faecalis) American Type Culture Collection (ATCC) 29212 and incubated for 24 h at 37°C. Debris extruded from the apical foramen during instrumentation was collected into vials. The numbers of Colony-forming units were determined for each sample.Statistical Analysis:The data obtained were analyzed using the one-way ANOVA followed by post-hoc tukey's test with a P = 0.05 as the level for statistical significance.Results:Results suggested a statistically significant difference in the number of colony forming units between four experimental rotary Nickel-Titanium instrumentation groups (P < 0.001).Conclusion:Although, extrusion of bacteria was found in all the experimental groups. There was less bacterial extrusion in K3 Group while more bacterial extrusion was seen in Mtwo Group.

Shaping Potential of Manual NiTi K-File and Rotary ProTaper and Analyzing the Final Outcome of Shaped Canals using CT

To assess and compare the shaping potential of manual NiTi K-files and Rotary ProTaper instruments in narrow canals using CT. To assess the shaping potential of manual NiTi K-files and Rotary ProTaper and analyzing the final outcome of shaped canals using CT and determining different variables, like • Working time • Change in volume • Change in cross-sectional area. From a pool of fifty freshly extracted permanent maxillary molars (1st and 2nd), 30 were selected with curvatures (20 to 40°) (Schneider 1971). Tissue fragments and calcified debries were removed from the teeth by scaling. The teeth were then stored in normal saline until used. All the mesiobuccal canals were scanned by CT to obtain preinstrumented images. Teeth were scaled and stored in normal saline. This study was divided in two groups with 15 samples each. GROUP I (PROTAPER ROTARY): Canals were instrumented with Protaper Rotary instruments using crown down technique according to manufacturer's instructions. GROUP II (NITI K-FILE): Were instrumented by NiTi K-files using step back technique with a quarter turn/pull motion. EVALUATIONS OF WORKING TIME: Comparative evaluations of working time was done for both the experimental groups. CT ANALYSIS AND MEASUREMENTS: The samples were analyzed and evaluated for: • Postinstrumentation change in volume. • Postinstrumentation change in cross-sections area. From the observations and statistical analysis carried out in this study, it was found that: There was a statistically significant difference between all the parameters judged for the present study that is: 1. Instrumentation with ProTaper Rotary system took significantly less time than instrumentation with manual NiTi K-file. 2. Change in the canal volume following instrumentation with ProTaper Rotary was significantly greater than that produced by manual NITi K-file. 3. a. Change in cross-section area at 2 and 3 mm from the apex was significantly greater with manual NiTi K-file as compared to ProTaper Rotary. b. Change in cross sections at 4.5, 6 and 7.5 mm from the apex with ProTaper Rotary was significantly greater than that produced by manual NITi K-file. This clearly establishes that there is a drastic difference in the shaping ability of manual and Rotary NiTi instruments used with step back and crown down technique respectively with the rotary instrumentation being faster and producing greater changes in the canal anatomy.

Effects of multiple root canal usage on the surface topography and fracture of two different Ni-Ti rotary file systems

The purpose of this study was to evaluate the effect of multiple root canal usage on the surface topography and fracture of Twisted File (TF) and ProTaper (PT) rotary Ni-Ti file systems, using scanning electron microscope (SEM). Ten sets of PT and TF instruments were used to prepare the mesial canals of mandibular first molars. TF 25, 0.06 taper and PT F1 instruments were analyzed by SEM when new and thereafter every three root canal usages. This sequence was repeated for both the TF and PT groups until 12 uses. Two images of the instrument were recorded, one of the instrument tip and the other 5 mm from the tip, both at × 100 magnification. The sequential use was continued till the instrument fractured and the number of root canal usages for the file to fracture was noted. All fracture surfaces were examined under the SEM. Fresh TF instruments showed no surface wear when compared to PT instruments (P < 0.05). Spiral distortion scores remained the same for both the groups till the 6 th usage (P > 0.05), while at the 9 th usage TF showed a steep increase in the spiral distortion score when compared to PT (P < 0.05). PT instruments fractured at a mean root canal usage of 17.4, while TF instruments showed a mean root canal usage of 11.8. Fractographically, all the TF instruments failed due to torsion, while all the PT instruments failed because of cyclic fatigue. PT instruments showed more resistance to fracture than TF instruments.

The effects of calcium hydroxide removal methods on bond strength of Epiphany SE with two irrigation protocols

Objective: The purpose of this study was to compare the effects of five calcium hydroxide removal methods on the bond strength of Epiphany SE sealer after canal irrigation with NaOCl+EDTA or NaOCl+MTAD. Materials and methods: The 120 roots were instrumented by using the ProTaper rotary system under irrigation with 2.5% sodium hypochlorite and randomly divided into two major groups according to the final irrigation: 1.3% NaOCl + MTAD and 5% NaOCl + 17% EDTA. For controls, 10 roots from each of the final irrigations with NaOCl + MTAD and NaOCl + EDTA (20 roots) were not filled with Ca(OH)2. The intra-canal paste, Ca(OH)2 was applied to each of the 100 remaining roots and stored at 37°C for 7 days. Each group was sub-divided into five sub-groups (n = 10) according to the removal technique for the intra-canal dressing: Group-1: recapitulation with size 30 K file + 3 ml of saline solution, Group-2: recapitulation with size 30 K file + 3 ml of 5% NaOCl, Group-3: using 5% NaOCl + 17% EDTA, Group-4: using 5%NaOCl + 15% citric acid, and Group-5: using 1.3% NaOCl + 5 ml MTAD. The root canals were filled with Resilon and Epiphany SE sealer. The bond strength was measured. Results: The mean bond strength of Epiphany SE to root dentine irrigated with NaOCl + MTAD was lower than that of NaOCl + EDTA. The highest bond strengths were 3.31 ± 0.057 and 2.60 ± 0.054 in the NaOCl + citric acid group when Ca(OH)2 was applied to roots treated with NaOCl + EDTA and NaOCl + MTAD, respectively (p < 0.05). Conclusion: For root canals treated with NaOCl + EDTA or NaOCl + MTAD, the use of NaOCl + chelating agent for Ca(OH)2 removal does not adversely affect the bond strength of Epiphany SE to dentin.

Antimicrobial effects of root canal medicaments against Enterococcus faecalis and Streptococcus mutans

To compare the antimicrobial activities of Activ Point (Roeko, Langenau, Germany), Calcium Hydroxide Plus Point (Roeko, Langenau, Germany), calcium hydroxide, 1% chlorhexidine gel and bioactive glass (S53P4) against Enterococcus faecalis and Streptococcus mutans. One hundred and twenty extracted single-rooted human teeth were used. After removing the crowns, root canals were prepared by using the Protaper rotary system. Following autoclave sterilization, root canals were incubated at 37 °C with E. faecalis ATCC 29212 and S. mutans RSHM 676 for 1 week. The specimens, which were divided into five treatment groups for each microorganism according to the intracanal medicament used, were tested in 10 experimental runs. In each experimental run, 10 roots were included as treatment, one root as positive control and one root as sterility control. Sterile paper points were utilized to take samples from root canals after the incubation of teeth in thioglycollate medium at 37 °C for 1 week. Samples taken from teeth by sterile paper points were inoculated onto sheep blood agar, and following an overnight incubation, the colonies grown on sheep blood agar were counted and interpreted as colony-forming units. Results were tested statistically by using Kruskal-Wallis and Conover's nonparametric multiple comparison tests. CHX gel (P < 0.001 and P < 0.001), Activ Point (P = 0.003 and P = 0.002) and Ca(OH)₂ (P = 0.010 and P = 0.005) were significantly more effective against E. faecalis than that of Ca(OH)₂ Plus Point and bioactive glass, respectively. On the other hand, compared with Ca(OH)₂ , CHX gel (P < 0.001), and Activ Point (P < 0.001), bioactive glass (P = 0.014) produced significantly lower colony counts of S. mutans. When compared with the positive control, treatment with Ca(OH)₂ Plus Point (P = 0.085 and P = 0.066) did not produce significantly lower colony counts of E. faecalis and S. mutans, respectively. Compared with the medicaments having an antimicrobial effect because of their alkaline pH, the medicaments containing chlorhexidine were effective against both E. faecalis and S. mutans.

The effect of root canal preparation on the development of dentin cracks.

Root fracture is not an instant phenomenon but a result of gradual development of tiny craze lines in tooth structure. Recent studies have shown that canal instrumentation has the potential to cause dentinal cracks. The purpose of this study was to evaluate and compare the formation of dentinal cracks caused by ProTaper rotary system to hand instrumentation. This in vitro study was carried out using 57 mandible incisor teeth. The teeth were decoronated. The roots were then examined to exclude cracked samples. A standard model for PDL simulation was used. The teeth were randomly divided into two experimental and one control group (n=19). The teeth in the experimental groups were prepared using hand or ProTaper Universal rotary instrumentation. The teeth in the control group were left unprepared. The teeth were then sectioned horizontally 3 and 6 mm from the apex, and the number of various dentinal defects was recorded using a dental operating microscope. The differences between groups were analyzed with Fisher's exact test. The hand group demonstrated significantly more defects than the control group (P=0.001). However, there was no significant difference between the rotary compared to the control and hand groups (P>0.05). There was no significant difference between groups with regards to fracture (P>0.05). Other defects including internal, external and surface cracks were more frequent in the hand than in the control or rotary groups (P=0.02), but the difference was not significant between the rotary and control groups (P>0.05). Canal preparation, whether hand or rotary, produces structural defects in dentin. The ProTaper rotary system when used according to the manufacturer's instructions, tends to produce fewer cracks and can be considered a safe preparation technique.

An In Vitro SEM Study on the Effectiveness of Smear Layer Removal of Four Different Irrigations.

The aim of this study was to compare the smear layer removal efficacies of 3% sodium hypochlorite (NaOCl), 17% Ethylenediaminetetraacetic acid (EDTA), SmearClear and BioPure MTAD using a common irrigation protocol. Fifty freshly extracted human single rooted maxillary and mandibular teeth were prepared by a ProTaper rotary system up to an apical preparation file size F3. Prepared teeth were randomly divided into five groups (n=10); distilled water (Group A; negative control), EDTA (Group B), SmearClear (Group C), BioPure MTAD (Group D) and NaOCl (Group E). After final irrigation with tested irrigants the teeth were decoronated, split into two halves longitudinally and observed under a scanning electron microscope (SEM) for removal of the smear layer. The SEM images were then analyzed for the amount of smear layer present using a three score system. Data were analyzed using the Kruskal-Wallis test and Mann-Whitney U test. Intergroup comparison of groups B, C, and D showed no statistical significant differences in the coronal and middle thirds, however, in the apical third the canal surfaces were cleaner in samples from group D (P<0.05). BioPure MTAD was the most effective agent for the purpose of smear layer removal in the apical third of the root canals.

Avaliação da manutenção odontométrica após instrumentação rotatória

The aim of this study was to analyze the working length after rotary instrumentation in upper molars. Forty-two upper molars were used, which were shaped by crown down technique using Protaper rotary system. The working length was performed after cervical and medium thirds shaping, and after apical shaping, the working length was evaluated visually again by a gutta percha master cone. The results showed that 23% of the molars do not have correct working length, principally the palatal root canal. Thus, it can conclude that rotary instrumentation can result on teeth shaped incorrectly, and morphologic position of root canal can influence in the final result of working length.

Effect of manual dynamic activation on smear layer removal efficacy of ethylenediaminetetraacetic acid and SmearClear: An in vitro scanning electron microscopic study

AbstractThe purpose of the present study was to evaluate the effect of manual dynamic activation (MDA) with a master gutta‐percha point on the smear layer removal efficacy of 17% ethylenediaminetetraacetic acid (EDTA) and SmearClear. Fifty freshly extracted human single‐rooted teeth were prepared using ProTaper rotary system up to F3 size. The prepared teeth were divided into five groups on the basis of final irrigation received. Group A: 3% NaOCl solution (negative control group). Group B: 5 mL of 17% EDTA. Group C: 1 mL of 17% EDTA + MDA for 2 min + 4 mL of 17% EDTA rinse. Group D: 5 mL of SmearClear. Group E: 1 mL of SmearClear + MDA for 2 min + 4 mL of SmearClear rinse. Prepared samples were decoronated and then longitudinally split into two halves and evaluated under scanning electron microscope. Representative images at coronal, middle and apical third level were taken and scored for the amount of smear layer present, using a three‐score system. The data were analysed through Kruskal–Wallis and Mann–Whitney U‐test. The root canal surfaces of samples of group C and group E (where MDA was done) were significantly cleaner in apical third regions than those of group B and group D (P &lt; 0.05).

Comparative Analysis of Accessory Mesial Canal Identification in Mandibular First Molars by Using Four Different Diagnostic Methods

IntroductionThe objective of the present in vitro study was to compare 4 diagnostic methods to identify accessory mesial canals (AMCs) in lower first molars. MethodsForty-four lower first molars were selected for assessment with cone-beam computed tomography (CBCT), digital radiography (DR), clinical inspection (CI), and dental operating microscope (DOM). Initially, axial images were obtained by using CBCT, and radiographs were taken in ortho, mesial, and distal angulations. The images were assessed by 2 independent groups of examiners, and all of the results obtained remained undisclosed until the end of the experiment. Subsequently, root canal access was prepared, and the mesial subpulpal groove was located by using sharp endodontic explorers. The roots were examined with DOM, and all identified canals were negotiated and instrumented by using a ProTaper Rotary System. The results were tabulated and statistically analyzed by nonparametric McNemar tests. ResultsTwelve AMCs (27.0%) were identified by CBCT, and 58.0% were instrumented. No AMCs were visualized in any DR examined. Fifteen potential AMCs (34%) were identified by CI, but only 47.0% were confirmed after instrumentation. Thirteen AMCs (30.0%) were identified by DOM, and 84.0% could be negotiated and instrumented. ConclusionsThere were statistically significant differences between the 4 types of assessments for AMC identification. There was good agreement between DOM and CBCT, whereas DR and CI were not as precise as either of the other 2 diagnostic methods.

Comparison of the cleaning capacity of Mtwo and ProTaper rotary systems and manual instruments in primary teeth

Root canal cleaning is an important step in endodontic therapy. In order to develop better techniques, a new generation of endodontic instruments has been designed. The aim of this study was to compare the effectiveness of manual K-files (Mani Co, Tokyo, Japan) and two rotary systems-Mtwo (Dentsply-Maillefer, Ballaigues, Switzerland) and ProTaper (VDW, Munich, Germany)-for root canal preparation in primary molars. India ink was injected to 160 mesiobuccal and distal root canals of mandibular primary molars. The teeth were randomly divided into three experimental groups and one control group. In each experimental group, either manual instruments (K-files) or rotary instruments (Mtwo or ProTaper) were used to prepare root canals. After cleaning the canals and clearing the teeth, ink removal was evaluated with a stereomicroscope. Statistical analysis was done with Kruskal-Wallis and Friedman tests. There were no significant differences in cleaning efficiency between manual and rotary instruments. Only ProTaper files performed significantly better in the coronal and middle thirds than in the apical third of the root canal. Manual K-files and the Mtwo and ProTaper rotary systems showed equally acceptable cleaning ability in primary molar root canals.

Ultra morphological changes of root canal dentin induced by 940 nm diode laser: An in-vitro study

Aim: The aim of this in-vitro study was to investigate the ultra-morphological changes of the root canal dentin after irradiation with 940 nm diode laser along with 2.5% sodium hypochlorite (NaOCl) and 17% ethylenediaminetetraacetic acid (EDTA) irrigation. Materials and Methods: Ten freshly extracted human permanent mandibular premolar teeth were selected. Teeth were decoronated and the working length was established. Cleaning and shaping was performed using protaper rotary system and the canals were enlarged up to F3 size. Canals were irrigated with 2.5% NaOCl between each instrument change and later with a final flush of 5 ml of 17% EDTA for 1 min. All the prepared teeth were then longitudinally grooved and split into two halves. One-half of each tooth (Group A) (n = 10) was analyzed without laser irradiation and other half (Group B) (n = 10) was analyzed after irradiation with 1.5 W continuous wave of 940 nm diode laser. Samples from both groups A and B were then subjected to scanning electron microscope analysis. Photomicrographs were taken at 2 mm, 7 mm, and 12 mm from the apex representing the apical, middle, and coronal regions at 2000Χ. Energy dispersive X-ray spectroscopy (EDX) analysis of the same samples was done under EDX analyzer to assess the calcium (Ca), phosphorus (P) and magnesium content and to determine the Ca P ratio. Results: Examination of the surface of the root canals revealed that, at middle and apical thirds smear layer removal was better with laser irradiated group. However, in the coronal third there was no statistically significant difference between both the groups. There was a mild variation in values when both group A and group B were compared to Ca, P, magnesium content, and the Ca phosphorous ratio but the difference was not statistically significant. Conclusion: 940 nm diode laser irradiation of root dentin along with NaOCl and EDTA irrigation, resulted in better removal of smear layer without significant additional loss of mineral content.

Effectiveness of three instrumentation systems to remove Enterococcus faecalis from root canals

To assess the effectiveness of three systems of mechanical preparation to reduce Enterococcus faecalis within root canals. Twenty-four human single-rooted canine teeth were standardized to a length of 17 mm and the canal contents removed using a size 20 K-file, as the last apical file. After irrigation and sterilization, the canals were contaminated with E. faecalis and incubated for 21 days at 37 °C with 5% CO(2). Then, the teeth were divided into three groups for mechanical preparation with: ProTaper rotary system, ProTaper manual system and manual K-files. Samples of the root canal contents, before and after the debridement, were collected with sterile paper points for 1 min. Then, the samples were diluted and plated in Brain Heart Infusion (BHI) agar. The colony-forming units were counted and the percentage reduction calculated. The reduction and log CFU mL(-1) were compared between groups using Wilcoxon nonparametric test and two-way analysis of variance, respectively. There was a significant reduction in the number of CFU/mL (P = 0.000) before and after debridement for all the systems used. However, there was no significant difference between the systems. All the three instrumentation systems reduced E. faecalis counts to a similar degree.