Rotary Technique Research Articles

Obturation of internally prepared cavities (simulating internal resorption) with three different techniques

Background and objectives:There is controversy as to which instrumentation and/or obturation techniques to choose for the treatment of the internal resorption defects. This in vitro study compared the instrumentation and obturation quality of simulated internal resorption cavities (IRC) with 3 different techniques. Methods:Ninety extracted human roots were used and sectioned transversely 5 mm from the apex and hemi-circular cavities were prepared in both sections. The sections were glued back together using superglue and embedded in plaster mold, thus obtaining root canals with cavities simulating internal resorption. The samples were randomly divided into 3 groups of 30 roots and instrumented by pro-taper rotary files, hybrid technique, or step-back technique, then each group subdivided into three subgroups of 10 roots and obturated with cold lateral condensation, warm vertical compaction, or injectable thermo-plasticized technique. After obturation, the samples were radio-graphed in Bucco-lingual and Mesio-distal view. After that, the plaster molds were removed, and the samples were then sectioned at the previous level and the quality of the obturation of the IRC were viewed under stereomicroscope. Results: There was highly significant difference between pro-taper rotary files compared with hybrid and step-back techniques. The results of obturation techniques radiographically and by stereomicroscope showed that there was highly significant difference in between injectable thermo-plasticized compared with other two techniques. Conclusion:The pro-taper rotary files and injectable thermo-plasticized technique gave the best results for treatment of simulated internal resorption cavities (IRC).

Excellent magnetic softness in TbFe/FeCoV multilayers

[Tb40Fe60(x nm)/Fe49Co49V2(y nm)](subscript N) multilayers were prepared by multitarget magnetron sputtering using a rotary turn-table technique in a stop-and-go mode. The multilayers were investigated using X-ray diffraction, field emission scan electron microscopy and vibrating sample magnetometry. The result shows that the coercive field drops abruptly with increasing number of bilayers, and it remains generally stable when the number of bilayers is 10 or higher. An excellent magnetic softness with a coercivity of 1.0 mT is obtained for x=5 and y=5 after annealing at 250℃. A crystalline state is observed in FeCoV layers before and after annealing by X-ray diffraction.

Comparison Between Rotary and Manual Techniques on Duration of Instrumentation and Obturation Times in Primary Teeth

The aim of this study was to compare the duration of instrumentation and obturation times and quality of root canal filling between rotary and manual instrumentation techniques in primary teeth. A randomized, controlled clinical trial was performed that included deciduous teeth with pulp necrotic. Forty necrotic teeth were included; 20 were instrumented with a rotary technique (experimental group) and 20 with a manual technique (control group). The time taken for instrumentation and for obturation were recorded in minutes, and the quality of the root canal filling was recorded as optimal, under-filled, or overfilled. The use of the rotary technique diminished the time of instrumentation to 63% and time of obturation to 68%, and it improved the quality of the root canalfilling. The use of rotary instruments in the pulpectomy of primary molars represents a promising technique; the time is significantly reduced.

Rotary Mtwo system versus manual K-file instruments: Efficacy in preparing primary and permanent molar root canals

To compare the cleaning ability and preparation time of rotary instruments (Mtwo) and conventional manual instruments (K-file) in preparing primary and permanent molar root canals. Access cavities were prepared in 70 primary and 70 permanent teeth and India ink was injected into 120 canals of selected molars. The teeth were randomly divided into two main subgroups (n=20) and three control groups (n=10). In each of these main subgroups, either the manual instrument (K-file) or the rotary system (Mtwo) was used to prepare root canals. After cleaning the canals and clearing the teeth, dye removal was evaluated with the help of a stereomicroscope. In addition, the time needed for root canal preparation was recorded by a chronometer. Statistical analyses were done using the Kruskal-Wallis, Mann-Whitney and t tests. With regard to the cleaning ability of root canals, there were no significant differences between the K-file and Mtwo rotary system in primary and permanent teeth in the apical, middle or coronal third of the canals. Moreover, there were no significant differences between primary and permanent teeth prepared with K-files and rotary instruments. In all the groups, shorter times were recorded with the rotary technique. The working time was shorter in primary than in permanent teeth. The Mtwo rotary system showed acceptable cleaning ability in both primary and permanent teeth, and achieved results similar to those of K-files in less time.

CT evaluation of apical canal transportation associated with stainless steel hand files, oscillatory technique and ProTaper rotary system

This study used computed tomography (CT) to compare apical canal transportation in mesiobuccal canals of maxillary molars prepared with different techniques. Sixty teeth were assigned to 3 groups (n=20), according to the technique used for root canal instrumentation: hand instrumentation with K-Flexofiles, K-Flexofiles activated by an oscillatory system and ProTaper NiTi rotary system. Pre and post-instrumentation CT images were obtained 3 mm short of the apical foramen and were superimposed to compare canal transportation. Data were analyzed statistically by ANOVA and Tukey's test using the SPSS software (α=0.05). In the buccal direction, the manual technique produced significantly less canal transportation than the oscillatory technique (p<0.05) and both were similar to the rotary technique (p>0.05). In the distal and distopalatal directions, the oscillatory technique produced more canal transportation (p<0.05). In the mesiopalatal direction, the oscillatory technique produced more canal transportation than the manual technique (p<0.05), and both were similar to the rotary technique (p>0.05). In conclusion, all techniques produced canal transportation, and the oscillatory technique produced the greatest removal of root dentin toward the innerside of the root curvature.

Morphometrical analysis of cleaning capacity of a hybrid instrumentation in mesial flattened root canals

The cleaning capacity of hybrid and rotary instrumentation techniques in mesial flattened canals of mandibular first molars was evaluated by morphometrical analysis in this study. Twenty human mandibular first molars were randomly assigned into two groups, according to instrumentation technique, as follows: group 1, instrumentation with ProTaper Starter Kit (Dentsply/Maillefer) rotary system; group 2, manual instrumentation using K files (Dentsply/Maillefer) by crown-down technique in middle and apical thirds, cervical preparation with Gates-Glidden #1 and #2 (Dentsply/Maillefer) burs, and to finalise the preparation, ProTaper F2 and F3 rotary files. Serial transverse cross-sections (5 µm) of the apical third, stained with hematoxylin and eosin, were analysed at 100× original magnification. The images were submitted to morphometrical analysis with an integration grid to determine the percentage of root canal area with debris. Statiscal analysis (t-Student, P < 0.05) showed significant difference between the techniques (P < 0.05), although neither completely cleaned the root canal.

Effectiveness of rotary or manual techniques for removing a 6-year-old filling material

The aim of this study was to evaluate the effectiveness of manual and rotary instrumentation techniques for removing root fillings after different storage times. Twenty-four canals from palatal roots of human maxillary molars were instrumented and filled with gutta-percha and zinc-oxide eugenol-based sealer (Endofill) , and were stored in saline for 6 years. Non-aged control specimens were treated in the same manner and stored for 1 week. All canals were retreated using hand files or ProTaper Universal NiTi rotary system. Radiographs were taken to determine the amount of remaining material in the canals. The roots were vertically split, the halves were examined with a clinical microscope and the obtained images were digitized. The images were evaluated with AutoCAD software and the percentage of residual material was calculated. Data were analyzed with two-way ANOVA and Tukey's test at 5% significance level. There was no statistically significant differences (p>0.05) between the manual and rotary techniques for filling material removal regardless the ageing effect on endodontic sealers. When only the age of the filling material was analyzed microscopically, non-aged fillings that remained on the middle third of the canals presented a higher percentage of material remaining (p<0.05) compared to the aged sealers and to the other thirds of the roots. The apical third showed a higher percentage of residual filling material in both radiographic and microscopic analysis when compared to the other root thirds. In conclusion, all canals presented residual filling material after endodontic retreatment procedures. Microscopic analysis was more effective than radiographs for detection of residual filling material.

Fast-Track Installation of Micropiles to Resupport Settled Florida SR-60 Bridge End Bents

The end bents of an existing bridge located west of Lake Wales, Florida, experienced significant settlement, leading to concern about its stability. A detailed foundation inspection attributed the settlement to deterioration of the existing timber piles. The bridge was closed to traffic until both end bents could be remediated. An adjacent bridge handled both directions of traffic during the closure. The geotechnical contractor proposed a solution of micropiles installed through both end bents to restore the bridge's capacity. Timing was a critical component of the remediation work. The micropile program consisted of the use of rotary drilling techniques to install 20 micropiles through the end bents to a depth of 30 ft. The tops of the micropiles were bonded to the end bent pile caps. A load test was performed on a test pile installed adjacent to the existing bridge.

Apical extrusion of debris after hand, engine-driven reciprocating and continuous preparation

PURPOSE: This in vitro study assessed the amount of debris extruded apically after preparation with different techniques. METHODS: Sixty healthy, extracted, human mandibular incisors were randomly divided into 3 groups: Group A - hand crown-down technique; Group B - crown-down technique with enginedriven rotary reciprocating instruments; Group C - Protaper: engine-driven continuous rotary instrumentation. The roots were immersed in 2.3 mL of distilled water. After preparation, the water in each tube was filtered to collect solid material extruded, and the filters were weighed using a precision scale. Data were analyzed by Kolmogorov-Smirnov and Kruskal-Wallis tests at the 0.05 level of significance. RESULTS: The statistical analysis showed that group C had significantly higher values of debris than groups A and B. CONCLUSION: The instrumentation using a continuous rotary technique, Protaper, produced greater apical extrusion than the hand and engine-driven crown-down techniques. The direction of instrumentation, whether cervical-apical or apical-cervical, seems to be a more important factor influencing apical extrusion than whether the instrumentation was performed by hand or was engine-driven.

Shaping ability of nickel-titanium rotary instruments in simulated S-shaped root canals

The aim of this study was to compare the shaping ability of 4 nickel-titanium rotary techniques and 1 hand technique in simulated S-shaped curved root canals. Seventy-five simulated double-curved resin root canals were divided into 5 groups (n = 15). The canals were compared at 12 different levels and at 3 different times: before preparation and after preparation to master apical 25 and 35. Data were statistically analyzed by performing 2-by-2 comparisons with the Tukey parametric test of variance analysis using a confidence interval of 95%. All of the 75 resin blocks presented transportation of the root canals by transforming the apical curvature into a straight zone and straightening the first curvature. When increasing the diameter from 25 to 35, both curvatures were straightened. Based on the conditions of this study, we can say that the flexibility of the instruments is inversely related with the transportation of the root canals, and that in the double-curved root canals, the apical curvature is always straightened.

Comparison of apical debris extrusion using a conventional and two rotary techniques.

Preparation techniques and instruments produce and push debris out of canals. This can induce inflammation within the periapical area. Therefore, instrumentation that causes less extrusion of debris is more desirable. The purpose of this in vitro study was to evaluate the quantity of debris extruded from the apical foramen during root canal preparation by using one hand, and two rotary instrumentation techniques. Three different groups each with 12 mesiobuccal roots of human maxillary first molar were instrumented using either step-back technique with hand instruments, FlexMaster or Mtwo rotary system. Debris extruded from the apical foramen during canal preparation was collected. The mean dry weights of debris were compared using one-way ANOVA. Step-back group had a significantly greater mean weight of debris compared to the other two groups (P<0.05). Mtwo group had the lowest mean weight of debris, though it was not significantly different from FlexMaster group. According to this study, the engine driven techniques were associated with less apical debris extrusion. [Iranian Endodontic Journal 2009;4(4):135-8].

A Retrospective Study of Endodontic Treatment Outcome between Nickel-Titanium Rotary and Stainless Steel Hand Filing Techniques

Aim The purpose of this study was to compare the periapical healing of molar root canal treatment using two instrumentation techniques. Methods A total of 225 maxillary and mandibular first and second permanent molars endodontically treated by undergraduate or postgraduate students were randomly selected from a computerized hospital database of which 110 molars had been prepared using a hybrid rotary technique with nickel-titanium instruments (group NR) and 115 with hand stainless steel files (group HF). Patients were recalled and the teeth were examined both clinically and radiographically for signs of periapical inflammation. Results Some 19% and 39% of teeth in the NR and HF group, respectively, were judged to have some form of procedural errors. A higher rate of periapical healing was noted for NR (77%) than the HF group (60%) (p < 0.05). Factors contributing favorably to treatment outcome included the use of rotary technique, maxillary molar, experienced operator, and absence of preoperative radiolucent lesion. Conclusion There was a higher incidence of procedural errors and a lower success rate for primary root canal treatment of teeth prepared with stainless steel files compared with the use of NiTi instruments in a continuous reaming action.

Root canal cleaning efficacy of rotary and hand files instrumentation in primary molars.

Pulpectomy of primary teeth is commonly carried out with hand files and broaches; a tricky and time consuming procedure. The purpose of this in vitro study was to compare the cleaning efficacy and time taken for instrumentation of deciduous molars using hand K-files and Flex Master rotary system. In this study, 68 canals of 23 extracted primary molars with at least two third intact roots and 7-12 mm length were selected. After preparing an access cavity, K-file size #15 was introduced into the root canal and India ink was injected with an insulin syringe. Sixty samples were randomly divided in to experimental groups in group I (n=30), root canals were prepared with hand K-files; in group II (n=30), rotary Flex Master files were used for instrumentation, and in group III 8 remained samples were considered as negative controls. After clearing and root sectioning, the removal of India ink from cervical, middle, and apical thirds was scored. Data was analyzed using student's T-test and Mann-Whitney U test. There was no significant difference between experimental groups cleaning efficacy at the cervical, middle and apical root canal thirds. Only the coronal third scored higher in the hand instrumented group (P<0.001). Instrumentation with Flex Master rotary files was significantly less time consuming (P<0.001). Although there was no difference in cleanliness efficacy at the apical and middle thirds, the coronal third was more effectively cleaned with hand files. Predictably, time efficiency was a significant advantage with rotary technique.

Effect of educational intervention on adoption of new endodontic technology by general dental practitioners: a questionnaire survey

To survey the clinical endodontic protocols of general dental practitioners (GDPs) in public dental clinics and to assess the effect of an educational intervention on the adoption of a nickel-titanium (Ni-Ti) rotary system. General dental practitioners in a Swedish Intervention County (IC), underwent an educational programme in endodontics. A follow-up questionnaire was posted to 98 GDPs in the IC and to 97 GDPs in a Control County (CC), where no specific training had been provided. The questionnaire concerned demographics, clinical endodontic protocols and instrumentation techniques. The response rate to the questionnaire was 87%. More than 90% of all GDPs reported they always or generally used rubber dam, determined working length, used the canal irrigant 0.5% buffered NaOCl and calcium hydroxide as an interappointment dressing. Two of three GDPs reported, they generally or always informed the patient of the prognosis. Every second GDP reported routines for postoperative recall and follow-up. The Ni-Ti rotary technique was reported to be completely adopted by 77% of the GDPs in the IC, significantly higher than in the CC (6%), P < 0.001. In the IC 79% of the GDPs reported they completed instrumentation in one treatment session, compared with only 32% in the CC, P < 0.001. The 'single-cone' mode of canal filling was reported to be significantly more frequent amongst GDPs in the IC, P < 0.001. General dental practitioners in both counties reported using contemporary clinical endodontic protocols. GDPs who had undergone an educational programme in Ni-Ti rotary instrumentation reported they had successfully integrated the technique into daily clinical practice.

Clinical evaluation of a chemomechanical method for caries removal in children and adolescents

Objective. The purpose of this study was to make a clinical comparison of the chemomechanical method for caries removal and the conventional rotary instruments technique when used in children and adolescents. Material and Methods. The study comprised 120 patients aged 3–17 years randomized into two groups: caries were removed chemomechanically in 60 patients and 60 patients received conventional treatment with rotary instruments. The outcome variables were: clinically complete caries removal, pain during caries removal, need for local anesthesia, treatment time, preferences of patients, and clinical success of the restorations during the 12-month evaluation period. Results. Complete caries removal was achieved in 92% of chemomechanically treated teeth and in all teeth treated with rotary instruments (p>0.05). The chemomechanical method significantly reduced the need for local anesthesia (p<0.001). Eighty-five percent of patients treated with Carisolv and 47% treated with rotary instruments were satisfied with the treatment (p<0.05). The mean time for chemomechanical caries removal was 11.2±3.3 min and 5.2±2.8 min for caries removal with rotary instruments (p<0.001). At the end of the 12-month evaluation period, there was no observed influence of the caries removal method on the survival of the restorations. Conclusions. The chemomechanical caries removal technique is an adequate alternative to the conventional rotary instruments method and is advantageous in pediatric dentistry.

Modeling of Aging Treatment of Flow-Formed AA6061 Tube

Flow-forming is a chipless metal forming process which employs an incremental rotary point deformation technique. An annealed AA6061 aluminum tubing preform was cold flow-formed into a seamless tube. A multiple pass flow-forming was performed. The strength of the flow-formed tube was altered by performing artificial aging treatment. The present research investigates the possibility of using response surface methodology (RSM) for predicting the hardness of the artificially aged flow-formed tube. Experiments were performed to investigate the effect of aging process parameters like solution time (ST), aging time (AT) and aging temperature (ATEMP) on the hardness of the flow-formed tube after artificial aging treatment. Experimental plan is performed by a standard RSM design called Box–Behnken Design. The results of analysis of variance (ANOVA) indicate that the proposed regression model obtained can adequately predict hardness values within the limits of the factors being studied.

The Effectiveness of Manual and Mechanical Instrumentation for the Retreatment of Three Different Root Canal Filling Materials

The aim of this study was to compare the effectiveness of the Mtwo R (Sweden & Martina, Padova, Italy), ProTaper retreatment files (Dentsply-Maillefer, Ballaigues, Switzerland), and a Hedström manual technique in the removal of three different filling materials (gutta-percha, Resilon [Resilon Research LLC, Madison, CT], and EndoRez [Ultradent Products Inc, South Jordan, UT]) during retreatment. Ninety single-rooted straight premolars were instrumented and randomly divided into 9 groups of 10 teeth each ( n = 10) with regards to filling material and instrument used. For all roots, the following data were recorded: procedural errors, time of retreatment, apically extruded material, canal wall cleanliness through optical stereomicroscopy (OSM), and scanning electron microscopy (SEM). A linear regression analysis and three logistic regression analyses were performed to assess the level of significance set at p = 0.05. The results indicated that the overall regression models were statistically significant. The Mtwo R, ProTaper retreatment files, and Resilon filling material had a positive impact in reducing the time for retreatment. Both ProTaper retreatment files and Mtwo R showed a greater extrusion of debris. For both OSM and SEM logistic regression models, the root canal apical third had the greatest impact on the score values. EndoRez filling material resulted in cleaner root canal walls using OSM analysis, whereas Resilon filling material and both engine-driven NiTi rotary techniques resulted in less clean root canal walls according to SEM analysis. In conclusion, all instruments left remnants of filling material and debris on the root canal walls irrespective of the root filling material used. Both the engine-driven NiTi rotary systems proved to be safe and fast devices for the removal of endodontic filling material.

Ex vivo study of manual and rotary instrumentation techniques in human primary teeth

This study aimed to evaluate, ex vivo, time and dentin removal by manual and rotary instrumentation in human primary teeth. Eighty primary teeth were divided into 2 groups, embedded in resin, and sectioned for evaluation before and after instrumentation. For manual technique, teeth were prepared using K-type files and rotary preparation was performed with Hero 642. All root canals were prepared up to size 40, and the instrumentation time was recorded. Dentin removal was calculated using digital image software. Data was statistically analyzed using chi-squared, Mann-Whitney, and t tests. Manual instrumentation removed more dentin in all groups compared with rotary instrumentation (P < .05). In some specimens, root perforations were observed in areas coinciding with largest root resorption. Rotary technique showed the shortest instrumentation time (P < .05). Deciduous teeth, without significant root resorption, have enough root structure for instrumentation up to size 40. Rotary technique required less time and generated less dentin removal.

Quantitative Evaluation of Debris Extruded Apically by Using ProTaper Universal Tulsa Rotary System in Endodontic Retreatment

This study evaluated the amount of apical debris during endodontic retreatment by using the ProTaper Universal Tulsa rotary files. Forty-five extracted human anterior teeth were root filled before randomly assigned to 3 groups. In group A, gutta-percha was removed by using the ProTaper Universal Tulsa retreatment system, and canals were re-prepared with ProTaper rotary files. In group B, gutta-percha was removed by using Hedström files with chloroform, and canals were reshaped with ProTaper rotary files. In group C, the same method as that in group B was used for gutta-percha removal, and canals were reshaped with K-flex files. Apical debris was collected and compared among 3 groups. Although all retreatment techniques resulted in apical extrusion, the ProTaper Universal Tulsa rotary technique in group A produced significantly less amount of apical extrusion than other 2 methods (P < .001). The ProTaper Universal Tulsa rotary technique proves to be a viable alternative method in endodontic retreatment.

Canal Transportation after Root Canal Instrumentation: A Comparative Study with Computed Tomography

This in vitro study used computed tomography (CT) to compare the occurrence of canal transportation in the apical third of mesiobuccal canals in maxillary molars instrumented with 3 techniques. Sixty teeth were assigned to 3 groups (n = 20), and the root canals were instrumented as follows: Group 1, hand instrumentation with K-files; Group 2, K-files coupled to an oscillatory system powered by an electric engine; Group 3, ProTaper NiTi rotary system powered by an electric engine. To compare the canal transportation produced by the different techniques, preinstrumentation and postinstrumentation 3-dimensional CT images were obtained from root cross-sections of the region located 3 mm short of the apical foramen of each root canal. The CT scans were exported to Adobe Photoshop software, and the initial and final images were superimposed to detect the root canal wall differences between them. Canal transportation was measured by the distance between the prepared canal center and the anatomic canal center. The manual technique produced lesser canal transportation (0.10 mm) than the oscillatory and rotary techniques (0.37 and 0.22 mm, respectively); this difference was statistically significant (P=.021). All studied techniques produced canal transportation.