Initial Working Length Research Articles

Does Root Canal Shaping Effect the Accuracy of Electronic Apex Locators in Curved and Straight Root Canals?

Objective: To assess the influence of root canal preparation (RCP) on the precision of electronic apex locators (EALs) in both straight and curved root canals. Methods: The experimental setup included forty-two extracted human mandibular molars featuring both straight distal canals (0-10 degrees) and curved mesial root canals (30-50 degrees). Initial working length (AWL1) measurements were conducted under a stereomicroscope at X15 magnification prior to root canal preparation (RCP). Subsequently, electronic working length (EWL1) was determined using two different electronic apex locators (EALs) – Propex-Pixi and EndoRadar. RCP was carried out with ProTaper Ultimate F1, F2 files in mesial canals, and F1, F2, F3 files in distal straight root canals. The RCP procedure involved the implementation of a standard irrigation protocol along with the use of a sonic device for activation. Following RCP, measurements were repeated under a stereomicroscope and documented as AWL2. EWL measurements were also repeated and recorded as EWL2 after the preparation. The variation was calculated by subtracting AWL from EWL for each tooth (EWL1-AWL1 and EWL2-AWL2). Statistical analysis employed Paired Sample t-test and Wilcoxon tests. Results: There was no statistically significant difference observed in the accuracy of Propex-Pixi and EndoRadar Pro before and after root canal preparation for both straight and curved canals. Conclusion: Root canal preparation did not alter the accuracy of the electronic apex locators (EALs) used in this study, whether applied to curved or straight root canals.

Comparative clinical assessment of working length endo-motor apex locator versus radiographic method in endo-dontic therapy.

Introduction: The technological and therapeutic advancements suggests that, choosing an appropriate endodontic approach is the key parameter to mitigate over radiation exposure and locating precise root canal length.Objective: Current study aims to evaluate the comparative accuracy of working length apex locator versus radiographic apex locator in in endodontic therapy among patients belonging from Sindh, Pakistan.Methodology: Current four-month duration based cross-sectional study focusing endodontic therapeutic techniques was conducted at Bibi Aseefa Dental College Larkana Sindh Pakistan. 124 patients requiring non-surgical root canal therapy were included in the study for working length apex locator and radiographic apex locator techniques. Film positioner were used to assess the morphology and initial working length of tooth by radiographic apex locator technique. Whereas glide path and working length was achieved with #12/02 M3 – Pro Gold File (United Dental) with 00 reading in Endo-Matic apex locator. Further data analysis was achieved with SPSS Version 20 and Microsoft Office 2010 multiple tools.Results: Among 124 patients, 69 (55.6%) were males and 55 (44.4%) were females with mean age of 33.60±12.87 years. We found comparative accuracy of 77 % of working length apex locator in terms of apical limit determination. Whereas, in case of radiographic apex locators 70 % accuracy was recorded.Conclusion: Working length endomotor with built in apex locators provide satisfac-tory control of apical limit of endodontic treatment and better time saving option, however radiographic confirmations remain the confirmatory length measurement tool to identify the dimension of canal and path obtained by endodontic instru-ment.Keywords: EndoMatic, Electronic Apex Locators, Hybrid Endomotors, Radiograph, Working Length.

CONSERVATIVE TREATMENT OF A TOOTH WITH INCOMPLETE ROOT DEVELOPMENT AND A LARGE PERIAPICAL LESION - A CASE REPORT

Background: Regenerative endodontic procedures have become increasingly popular in recent years. This paper reports the use of regenerative endodontics in the treatment of a large cyst-like inflammatory periapical lesion in an immature permanent tooth. Case report: A 12-year-old boy with a submucosal abscess in the upper jaw visited the Department of Pediatric Dentistry. Previous injury in the area was reported. The X-ray showed a well-defined large osteolytic lesion engaging the apical part of the root. The initial treatment plan included creation of MTA plug and apical surgery. Throughout the treatment course, the patient skipped his appointments and returned 8 months later. The initial working length couldn't be reached, and a hard barrier was present in the middle portion of the root canal. The CBCT showed that the size of the lesion had decreased significantly. Bone-like tissue with a density similar to surrounding spongiosis was observed in the root canal. There was no change in the contour and length of the root walls. Conclusion: Regenerative endodontics could be successfully used in the treatment of some immature permanent with necrotic pulp and large periapical lesions.

Influence of Charge Quality on Physical, Mechanical and Operational Properties of Low-Alloy Steel 30KHGSA

Purpose of reseach is to study the influence of the quality of the original charge on the complex of physical, mechanical and operational properties of structural low-alloy steel 30HGSA.Methods. As an object of research, a typical representative of low-alloy structural steels has been chosen - steel 30HGSA, smelted using metallized sponge iron pellets, ordinary scrap metal and billets obtained by the method of a boiling slag layer. In accordance with the set objectives of the study, steel 30HGSA of various melts, obtained with different charge, had the same conditions for melting, evacuation, deoxidation, casting and crystallization. The casting temperature was 1600...1620 оC and the post-vacuum treatment temperature was 1530...1560 °C. Duration of evacuation - 5 minutes. Casting of melts was carried out into cast iron molds with a siphon for 4 ... 5 minutes. Deoxidation was carried out in a ladle with aluminum in the amount of 4 ... 4.5 kg / melt. After solidification, the ingots were cooled in special wells. The ingots were cut into 3 parts: head, middle and bottom (600 × 600 mm). The middle part was then hot forged and rolled to a Ø30 mm bar. The length of the rod was 2 ... 3.4 m. After hot deformation, the rods were cooled in air.Results. Mechanical tests have been carried out. Statistical processing of experimental results has been performed. Regularities of changes in the characteristics of mechanical properties have been revealed: tensile strength, creep strength, relative narrowing of the cross-sectional area of the sample, relative elongation of the initial working length, impact strength (σВ, σ0.2, ψ, δ, aН).Conclusion. It has been found that with an increase in temperature, the mechanical properties of steel 30HGSA, smelted on various charges, decrease. It has been established that the cold brittleness threshold of 30HGSA steel is lower for purer melts on spongy iron and intermediate product KShS, the value of impact toughness at low temperatures is higher than in melting on a conventional metallized charge. Noticeable softening begins at a tempering temperature of 300 °C The temperature of the maximum tempering brittleness for steel 30HGSA, melted on a conventional metallized charge, is 550 °C It is shown that steel 30HGSA smelted with a pure original charge (spongy iron) has a lower tendency to temper brittleness than steel smelted with a conventional charge. The value of the impact toughness of the steel of this melt is higher than that of the steel of conventional melting over the entire tempering temperature range.

COMPARING THE EFFECTIVENESS OF HYFLEX ROTARY AND HAND – OPERATED  INSTRUMENTS IN PREPARING MESIO-BUCCAL ROOT CANALS OF MANDIBULAR PERMANENT FIRST MOLARS

Objectives: To compare the effectiveness of Hyflex rotary and NiTiflex hand-operated instruments in regard to 4 parameters of root canal preparation: the working time, the alteration of canal curvature and working length, obturating efficacy. Materials and methods: A total of 20 mesio-buccal root canals of mandibular first molars were randomly divided into two similar groups. Group 1 root canals were prepared with Hyflex rotary files according to the manufacter’s instructions. Group 2 with NiTi manual instruments in crown-down technique. Based on radiographs taken prior to instrumentation with the initial instruments inserted into the canals, the 2 groups were balanced with respect to the angle of canal curvature and working length. Canals were prepared using a crown - down preparation technique as instructed by the manufacturer. Group 1 was prepared by rotary Hyflex files and group 2 was prepared by NiTiflex hand-operated instruments. The assessment of changes of canal curvature and working length was based on radiographs taken prior and post instrumentation. The time required for canal preparation was recorded for each specimen. Postoperative teeth were examined clinically and radiographically after 1 week and 3 months. Research design was prospective clinical trials, group comparison. Data was statistically analysed using the SPSS 16.0 software. Results: Rotary Hyflex files prepared significantly faster and maintained the original canal curvature better than hand - operated Nitiflex files (p < 0.05). There was no significant differences in maintaining initial working length of two groups (p > 0.05) and both hand NiTiflex and rotary Hyflex instruments showed 1 case of ledge formation for each, 1 NiTiflex file separation and no perforation or apical transportion. Three-month clinical results were equal: in rotary Hyflex group, 90% teeth of successful result, 10% teeth in suspect; in NiTiflex hand-operated group, 80% ratio of successfully- treated teeth, 10% suspect and 10% failing result. Conclusions: Under the conditions of this clinical study, both instruments were safe to use, showed equally efficacy in preparing root canals and endodontic clinical results. However, rotary Hyflex significantly reduced working time and respected original canal curvature better than hand–operated NiTiflex files, with higher treatment cost from 9 to 10 times. Key words: cleaning, shaping, root canals, rotary, canal curvature

Accuracy of the Electronic Apex Locator in Relation to Patient’s Cooperative Behavior

Background Root canal length measurement during pulpectomy procedure is an important step for a successful treatment results. The aim of this study is to clinically evaluate the affect of patient’s cooperative behavior on the accuracy of Root ZX (EAL). Materials and Methods Thirty-five primary anterior teeth undergoing pulpectomy procedure in 19 healthy children selected. Root ZX (EAL) used for determining the root canal length electronically. X-ray exposure is done with file in place to confirm the initial working length. Using the digital ruler in the Romexis software the radiographic root canal length measurement is estimated. Afterwards, pulpectomy procedure is completed. Results t-test showed no statistical significant difference p = .132 between the Root ZX (EAL) and digital radiography in determining the root canal length in primary anterior teeth. Considering that the clinically acceptable error tolerance should be ±1 mm, Root ZX (EAL) showed an accuracy of (85.7%) in 18 and 12 (++ve) and (+ve) behavior patients, respectively. Conclusion Root ZX (EAL) showed acceptable accuracy and are comparable to digital radiography in measuring root canal length in primary anterior teeth in children with positive and definitely positive behavior.

Working length changes in curved canals after coronal flaring by using rotary files and hand file: An in vitro study

Aim:This in vitro investigation examined the effect of early coronal flaring (CF) and late CF on the working length (WL) in curved root canals.Background:The objective of this study was to determine if canal length is altered as a result of CF in curved canals of molar roots.Study Design:The conditions compared were combinations of (a) stainless steel hand files using Gates Glidden (G. G.) drills (SS) versus nickel-titanium rotary files (Ni-Ti); and (b) early CF (flaring completed before WL determination) versus late CF (flaring completed after WL determination). Selected were 90 canals of extracted maxillary or mandibular first molars (mesial root of mandibular molars and the mesiobuccal root of the maxillary molars) from three groups. CF was accomplished for the SS group using G. G. drills and for the Ni-Ti group using rotary ProTaper and Hero Shaper files. WL was determined by a digital vernier caliper before CF, immediately after CF, and again after canal preparation.Statistical Analysis:A repeated measures analysis of variance (ANOVA) test and a Tukey's multiple prosthoc test were used for this study.Results:Results indicated that WL decreased for all canals as a result of canal preparation. The mean decrease in WL was significantly greater for the SS group (−0.77 ± 0.42 mm) than for the Ni-Ti groups (−0.33 mm ± 0.44). Less change in WL occurred in all groups when initial WL was determined after CF.Conclusion:WL in curved canals consistently decreases during the course of instrumentation. Clinician should keep this in mind for better treatment outcome.

Effect of Canal Length and Curvature on Working Length Alteration with WaveOne Reciprocating Files

Introduction This study evaluated the working length (WL) modification after instrumentation with WaveOne Primary (Dentsply Maillefer, Ballaigues, Switzerland) reciprocating files and the incidence of overinstrumentation in relation to the initial WL. Methods Thirty-two root canals of permanent teeth were used. The angles of curvature of the canals were calculated on digital radiographs. The initial WL with K-files was transferred to the matched WaveOne Primary reciprocating files. After glide paths were established with PathFile (Dentsply Maillefer, Ballaigues, Switzerland), canals were shaped with WaveOne Primary referring to the initial WL. The difference between the postinstrumentation canal length and the initial canal length was analyzed by using a fiberoptic inspection microscope. Data were analyzed with a balanced 2-way factorial analysis of variance ( P < .05). Results Referring to the initial WL, 24 of 32 WaveOne Primary files projected beyond the experimental apical foramen (minimum–maximum, 0.14–0.76 mm). A significant decrease in the canal length after instrumentation (95% confidence interval ranging from −0.34 mm to −0.26 mm) was detected. The canal curvature significantly influenced the WL variation (F 1 = 30.65, P < .001). The interaction between the initial canal length and the canal curvature was statistically significant (F 2 = 4.38, P = .014). Conclusions Checking the WL before preparation of the apical third of the root canal is recommended when using the new WaveOne NiTi single-file system.

Intratunnel Fixation Versus Extratunnel Fixation of Hamstring Anterior Cruciate Ligament Reconstruction –A Meta-Analysis

Hamstring anterior cruciate ligament (ACL) reconstructions fixed inside both bone tunnels have a shorter initial working length, and thus should be stiffer than those fixed outside both bone tunnels. We used meta-analysis to compare 4-stranded hamstring ACL reconstructions using the 2 fixation methods with reconstructions using patellar tendon autografts. A Medline database search of English-language articles published through June 2004 yielded 36 studies that met the inclusion criteria: 5 intratunnel fixation studies (569 patients), 10 extra-tunnel fixation studies (604 patients), and 24 patellar tendon studies (1592 patients). Three studies included both patellar tendon and hamstring reconstructions. Demographically, all 3 groups were similar. There was no significant difference in the percentage of knees restored to normal instrumented laxity measurements between the 3 groups, nor was there a difference in graft failure rate. Patient satisfaction and return to preinjury activity rates were similar between the intratunnel fixation and patellar tendon groups and were significantly lower for the extra-tunnel fixation group. Good International Knee Documentation Committee scores did not correlate with good patient satisfaction or return to preinjury activity.

Influence of Apical Constriction Diameter on Root ZX Apex Locator Precision

Small-diameter hand files are systematically used to determine the initial working length and to establish patency of the root canal. In wide canals, electronic apex locator accuracy might be influenced by file size. This article reports on a study to assess the influence of apical constriction diameter on the precision of the Root ZX apex locator by using files of varying diameter on teeth with 3 different degrees of apical widening: 0.37, 0.62, and 1.02 mm. Ten extracted single-root teeth, stored in saline solution at 37 degrees C, were sectioned at the enamel-cement junction and embedded in an alginate mold. Initial working length (L0) was determined with a #10 Kerr file, and canals were irrigated with either 50% citric acid or 5.25% sodium hypochlorite. To assess the ability of the locator to identify the narrowest area of the root canal as constriction diameter increased, the canal was progressively widened by insertion of files of increasing diameter (10-100) at a point L0+1 mm. After each enlargement, the working length (L) was redetermined, with files from #10 (L10) up to the file used for widening. Comparison of statistical results was based on the difference between final working length and initial length (L10) for each apical width. Statistical analysis was carried out with analysis of variance test for comparison of means. Results showed that at apical constriction widths of 0.37 and 0.62 mm, there was no significant difference between initial working lengths as determined by a Kerr #10 file and final working lengths after widening with files of up to #60. In those teeth whose apical width had been increased to 1.02 mm, there was no statistically significant difference between initial and final working lengths as measured by files from #10-#25; however, significant differences were apparent between #10 and #30, #35, or #40 (P<.05), and the degree of significance increased considerably (P<.001) for files #45 or greater. These results suggest that Root ZX apex locator precision varies as a function of apical constriction diameter.

Influence of different methods of cervical flaring on establishment of working length

Objective:to investigate the influence of three different rotary systems for cervical flaring on establishment of the real working length. Material and methods: Thirty mandibular first molars were submitted to conventional endodontic access and initial working length measurement, followed by irrigation/suction of the pulp chamber with 5% sodium hypochlorite. Teeth were randomly divided into 3 groups (n=10) and cervical flaring of the mesiobuccal canals were performed using one of the following instrument systems: Group 1 – Gates-Glidden burs; Group 2 – Orifice Openers; Group 3 – La Axxess system. Two subsequent numbers of instruments of each rotary system were used and the final working length was recorded. A digital calyper was used to record the working length, in millimeters, to investigate a possible discrepancy between initial and final measurements.Results:Analysis of variance (Anova) na Tukey test revealed statistical difference between Group 1 and Groups 2 and 3 (p£ 0.05).Conclusions:all groups presented shorter working length after cervical flaring; groups prepared with instruments La Axxes and Orifice Opener presented the best results among the systems studied.

An accuracy of the several electronic apex locators on the mesial root canal of the mandibular molar

The aim of this study was to compare the length between the mesio-buccal and mesio-lingual canal of the mandibular molars before and after early coronal flaring at the different measuring time using several electronic apex locators. Fifty mandibular molars with complete apical formation and patent foramens were selected. After establishing the initial working length of the buccal and lingual canal of the mesial root using a surgical microscope (Carl Zeiss Co Germany) at 25X with #15 K-fle tip just visible at the foramen, radiographs were taken for the working length. After measuring the length of mesio-buccal and mesio-lingual canal (control group), the electronic lengths were measured at different times using several electronic apex locators (experimental groups; I-Root ZX, II-Bingo, III-Propex, IV-Diagnostic). After early coronal flaring using the file, the additional electronic lengths were measured using the same manner The results were as follows: One canal has a correct working length for the mesial root of the mandibular molar, it can be used effectively for measuring the electronic working length of another canal when the files are superimposed or encountered at the apex. In addition, the accuracy of the electronic apex locators was increased as the measurement was accomplished after the early coronal flaring of the root canal and the measuring time was repeated.

A comparison of the length between mesio-buccal and mesio-lingual canals of the mandibular molar

The aim of this study was to compare the initial apical file (IAF) length between the mesio-buccanl and mesio-lingual canals of the mandibular molar before and after early coronal flaring. Fifty mandibular molars with complete apical formation and patent foramens were selected. After establishing the initial working length of the buccal and lingual canal of the mesial root using the Root-ZX, radiographs were taken for the working length with a 0.5 ㎜ short of #15 K-file tip just visible at the foramen under a surgical microscope (OPMI 1-FC, Carl Zeiss Co. Germany) at 25X. After early coronal flaring using the K 3 file, additional radiographs were taken using the same procedure. The root canal morphology and the difference in working length between the buccal and lingual canals were evaluated. These results show that the difference in the length between the mesio-buccal and mesio-lingual canals of the mandibular molar was ≤ 0.5 ㎜. If one canal has a correct working length for the mesial root of the mandibular molar, it can be used effectively for measuring the working length of another canal when the files are superimposed or loosening. In addition, the measured the working length after early coronal flaring is much more reasonable because the difference in the length between the mesio-buccal and mesio-lingual canals can be reduced. [J Kor Acad Cons Dent 29(6):541-547, 2004]

Effect of Early Coronal Flaring on Working Length Change in Curved Canals Using Rotary Nickel-Titanium Versus Stainless Steel Instruments

This in vitro investigation examined pre- and postinstrumentation working length (WL) measurements in curved root canals. The conditions compared were combinations of (a) stainless steel hand files + Gates Glidden drills (SS) versus nickel-titanium rotary files (Ni-Ti); and (b) early coronal flaring (flaring completed before WL determination) versus late coronal flaring (flaring completed after WL determination). Coronal flaring was accomplished for the SS group using Gates Glidden drills and for the Ni-Ti group using rotary Ni-Ti files (n = 15/group). WL was determined before coronal flaring, immediately after coronal flaring, and again after canal preparation. Results indicated that WL decreased for all canals as a result of canal preparation. The mean decrease in WL was significantly greater for the SS group (-0.48 mm +/- 0.32) than for the Ni-Ti group (-0.22 mm +/- 0.26). Less change in WL occurred in both groups when initial WL was determined after coronal flaring (SS: -0.12 mm +/- 0.13, Ni-Ti: -0.14 mm +/- 0.25).