In vivo comparison of the accuracy of two electronic apex locators

The aim of this study was to analyse in vivo the accuracy of two apex locators, Root ZX and Novapex, to determine the position of the apical constriction. Twenty-three human single-rooted teeth to be extracted for periodontal reasons constituted the experiment. Endodontic access was obtained and the apical constriction was determined by one of the apex locators after initial crown-down preparation. When the electronic marker indicated that the tip of the endodontic file was at the apical constriction, the teeth were filled with composite and then surgically removed. The presence of the endodontic file tip at the apical constriction was evaluated stereomicroscopically (30×) and confirming radiographs were exposed. The accuracy of Root ZX and Novapex was 91.7% and 81.8% respectively. Within the limits of this study, the evaluated apex locators have a similar clinical performance for the apical constriction location.     

Ex vivo evaluation of the ability of four different electronic apex locators to determine the working length in teeth with various foramen diameters

BACKGROUND: The aim of this ex vivo study was to evaluate the accuracy of four electronic apex locators (EALs) to determine the working length in teeth with various foramen diameters. Our previous study revealed that electronically measured canal length was influenced by the root canal diameter. It is not known whether foramen size would interfere with the reading accuracy of an EAL. METHODS: A total of 36 extracted human lower single rooted premolar teeth were divided into four groups of nine teeth each. In groups A, B and C, the root canals were instrumented using #10-80, #10-100 and #10-120 K-files, and the tip of size #80, #100 and #120 K-files were permitted to pass through the apical foramen to a length of 1mm, respectively. In group D, the teeth were instrumented using #10-140 K-files and the tip of #140 K-file was permitted to pass through the apical foramen to a length of 5 mm. Thus, the average apical foramen diameters in groups A, B, C and D were approximately 0.82 mm, 1.02 mm, 1.22mm and 1.5 mm, respectively. The teeth were then mounted in 1% agar and four EALs were used: Root ZX, Foramatron D10, Apex NRG and Apit 7. For electronic measurement, sizes #10 and #80, #10 and #100, #10 and #120, and #10 and #140 K-files were used for groups A, B, C and D, respectively. During electronic measurement the canals were flushed with 6% sodium hypochlorite solution. RESULTS: Three-way ANOVA and Bonferroni test showed that EAL, file size and foramen size all had a significant influence on the measurement error (P<0.0001), with all the interactions between these three factors being significant (P<0.0001). CONCLUSIONS: The four EALs were unreliable to determine the working length of teeth with a wide apical foramen, when using a small size file. The Root ZX and Foramatron D10 showed significantly better scores than the other two EALs and may be more reliable to determine the working length of teeth with a wide apical foramen, if a tight-fit file is used.     

A comparison between two electronic apex locators: an in vivo investigation

AIM: To compare in vivo the Apex Finder and Root ZX electronic apex locators (EALs) at five different stages during root canal instrumentation. METHODOLOGY: The Apex Finder and Root ZX were used in 64 teeth with either vital or necrotic pulps. Informed consent was obtained by each patient under a study protocol approved by an ethical committee from the University of Trieste. Measurements were made: (stage 1) before instrumentation and irrigation; (stage 2) after brief filing, irrigation with 70% isopropyl alcohol and partial drying; (stage 3) after canal lubrication with EDTA gel (RC-Prep); (stage 4) after complete instrumentation and irrigation with NaOCl 5%; (stage 5) after drying of the final instrumented canal. Stages 2, 3 and 5 were considered low canal conductivity conditions and stage 4 as high. Teeth were then extracted and a size 15 K-file was inserted until its tip was observed under stereomicroscope to reach the foramen and the corresponding length was recorded to an accuracy of 0.25 mm and compared with values derived from the EALs. RESULTS: The data revealed 133 unstable measurements (out of 640): some (68) related to low canal conductivity conditions (more frequently for Root ZX, 67; P < 0.05), and others (63) related to NaOCl presence in the canal (more frequently for Apex Finder, 58; P < 0.05). Accuracy was calculated only on stable measurements. The Root ZX showed significantly (P < 0.05) more precise measurements overall (-0.03 +/- 0.39 mm) compared with the Apex Finder (-0.31 +/- 0.46 mm). Under dry canal conditions the Apex Finder provided the greatest accuracy (-0.0 +/- 0.21) compared with the Root ZX (-0.05 +/- 0.32) (significance P < 0.05). CONCLUSIONS: Under the five different clinical situations both EALs revealed accurate measurements. Apex Finder was negatively influenced by NaOCl in the root canal. The Root ZX was more frequently unable to reveal stable measurements in low conductivity canals.     

A comparison between two electronic apex locators: an ex vivo investigation

AIM: To compare ex vivo the performance of the Apex Finder and the Root ZX apex locators, with and without irrigant, in canals having different diameters. METHODOLOGY: Sixty canals in 60 teeth were prepared using stainless steel hand files and 0.04 taper NiTi rotary instruments. During preparation the narrowest diameter of the canal was transported to the apical root surface. The canals were irrigated with RC-Prep and 5% NaOCl solution. Six groups were obtained, each with 10 canals having the same diameter of foramen, either 0.15, 0.20, 0.25, 0.40, 0.60 and 0.80 mm. A size 15 K-file was advanced into each canal until its tip was observed under x10 magnification to reach the foramen and the corresponding length recorded. The measurements were performed to an accuracy of 0.25 mm as a base unit of length. The teeth were then fixed to a plastic bar suspended over a glass container filled with 0.9% NaCl solution. Each apex locator was tested when the K-file was at the foramen, or 0.5, 1.0, 1.5 and 2.0 mm short; with the root apex immersed into the solution; with the canal dry or irrigated with NaCl. To evaluate the accuracy of both electronic apex locators (EALs) each electronically determined distance was compared with the actual length and the data analysed using the General Linear Model and the Student t-test. RESULTS: Out of 2400 measurements 100 were electrically unstable, all with the Root ZX. In total, 521 measurements located the position of the file tip beyond the apex, in general, in high conductive conditions with the Root ZX and in low conductive conditions with the Apex Finder. No significant difference in terms of accuracy was found between the two EALs when the file tip was at the foramen (Root ZX mean +0.12 mm, SD 1.22 mm; Apex Finder mean +0.57 mm, SD 1.16 mm). Comparing all the measurements performed with the file tip within 2 mm of the foramen, in all the different conditions tested, the accuracy was affected (P<0.025) by diameter of the foramen, type of EAL, distance to the apex, and by several interactions. CONCLUSIONS: Under the different ex vivo conditions both EALs provided accurate measurements when the file tip was at the foramen. The accuracy of the Apex Finder was negatively influenced by high conductive conditions, whilst the Root ZX provided inaccurate and unstable measurements mostly in low conductive conditions.     

2种根尖定位仪测定根管长度准确性的比较

目的研究Raypex 5和Elements Diagnostic 2种根尖定位仪测量根管长度的准确性。方法收集40颗单根管下颌前磨牙,首先借助K锉测定实际根管长度,然后再分别使用Raypex 5和Elements Diagnostic 2种根尖定位仪测定根管长度,得到电测长度与实际长度的差值,对结果进行分析比较。结果 Raypex 5根管长度测量的准确率是87.5%,Elements Diagnostic 92.5%,两者准确率差异无统计学意义(P>0.05)。结论临床使用2种根尖定位仪对根管长度的确定都是较为精确和有效的。     

2种根尖定位仪准确性的临床评价

目的 评价2种根尖定位仪的准确性。方法 选取因修复需要根管治疗的上前牙,共40个根管。要求未罹患任何牙体牙髓疾病,具有正常牙髓活力。局麻下常规开髓,分别选用第三代电子根管测量仪ROOT ZX及第四代产品VDW Raypex5测量工作长度。随后插针进行牙CT拍摄,从牙CT影像中得到根尖孔位置,测得工作长度,并以此作为金标准。引入经典流行病学中对诊断试验评价的方法,采用SPSS13.0软件,根据测得数据绘制受试者工作特性曲线（receiver operator characteristic curve,简称ROC曲线）,按曲线下面积,比较几种诊断试验的诊断效率。结果 ROOT ZX和VDW Raypex5的准确率分别为87.5%和92.5%。ROC曲线下面积ROOT ZX为0.489,VDW Raypex5为0.505。结论 ROOT ZX和VDW两代产品都对根管工作长度的测量结果准确、安全、可靠。ROC曲线是一种全面、准确评价诊断试验有效的方法。     

Accuracy of an electronic apex locator in primary teeth with root resorption

Aim  To evaluate whether root resorption of primary molar teeth affects the accuracy of the Root ZX apex locator and to compare the Root ZX at different meter readings with direct canal measurement.
Methodology  Sixty extracted primary molar teeth with root resorption affecting one sixth to one third of root length were used. The teeth were embedded in an alginate model. A K-type file was used in association with a Root ZX apex locator to measure canal length. Measurements were recorded using the Root ZX meter reading 'Apex' and '0.5 bar'. Actual tooth length was measured with a K-file to the major foramen. All measurements were read under a stereomicroscope at 15× magnification. The deviation of the Root ZX measurement from the actual canal length was determined.
Results  Mean differences between Root ZX length meter reading 'Apex' and actual length were 0.01 ± 0.23 mm whereas mean differences between Root ZX length meter reading '0.5 bar' and actual length were −0.33 ± 0.30 mm. The Root ZX was 96.7% accurate to within ± 0.5 mm of the apical foramen when compared with the actual canal length of primary molars with root resorption.
Conclusions  Using a criterion of ± 0.5 mm, the accuracy of the Root ZX was high and not affected by root resorption. When compared with direct canal measurement, the error in locating the apical foramen was smaller with measurement at meter reading 'Apex' than meter reading '0.5 bar'.     

Accuracy of two electronic apex locators in primary teeth with and without apical resorption: a laboratory study

Aim To evaluate the accuracy of the Root ZX (J Morita Corp., Kyoto, Japan) and Tri Auto ZX (J Morita Corp.) devices for measuring root canal length in primary teeth with and without apical resorption. Methodology Thirty‐four extracted human primary molar teeth with resorption and 19 primary teeth without resorption were collected. After endodontic access preparation, the actual lengths of the teeth were determined. The teeth were then embedded in an alginate model to determine the electronic working length measurement. Statistical evaluation was completed using Student’s t‐tests. Results For the Root ZX, there was no significant difference between those teeth with root resorption and those without. However, for the Tri Auto ZX, there was a significant difference in the electronic measurements between those teeth with root resorption and those without (P < 0.05). Significant differences were found amongst the measurements of the two apex locators (P < 0.05). For root canals with resorption, the respective accuracy rates (within ±0.5 mm) of Root ZX and Tri Auto ZX were 83.33% and 89.47%; within ±1 mm, the Root ZX and Tri Auto ZX demonstrated 98.95% and 100% accuracy, respectively. For root canals with no resorption, the percentage of measurements within ±0.5 mm of the apical construction was 89.28% for the Root ZX and 80.35% for the Tri Auto ZX. The accuracy within ±1 mm of the Root ZX and the Tri Auto ZX was 98.22% and 100%, respectively. Conclusion Within the limitations of this laboratory study, the presence of resorption affected the performance of the Tri Auto ZX more than the Root ZX.     

An in vivo comparison of working length determination of two frequency-based electronic apex locators

Aim  To compare in vivo the accuracy of two electronic apex locators (EALs) by means of digital radiographic imaging system.
Methodology  Electronic working lengths of 831 canals were determined with the DentaPort ZX and Raypex 5 apex locators and confirmed radiographically. The radiographic images acquired with the aid of a digital radiographic imaging system (VisualiX eHD; Gendex Dental Systems, Des Plaines, IL, USA) were blindly analysed by two independent evaluators. The distance between the file tip and the radiographic apex was measured using dedicated software (VixWin Pro, Gendex Dental Systems, Des Plaines, IL, USA) and the mean distance achieved between different tooth type and EALs were compared statistically. Statistical analyses were performed using the t -test for independent samples and one-way anova with the null hypothesis set as 5%. Positive or negative values were recorded when the file tip was detected beyond or short of the radiographic apex, respectively.
Results  The mean distance between file tip and radiographic apex were −1.08 ± 0.73 and −1.0 ± 0.67 mm considering DentaPort ZX and Raypex 5 groups, respectively, with no significant differences ( P  > 0.05). No statistically significant differences were found amongst the same tooth type when comparing both groups ( P  > 0.05) or amongst different teeth type in the same group ( P  > 0.05).
Conclusions  Within the limitations of this in vivo study, the DentaPort ZX and Raypex 5 were similar in terms of accuracy.     

根尖定位仪测量根尖破坏牙根管长度的准确性研究

目的 比较Root ZX,Propex,Justy Ⅱ和 Raypex5 4种根尖定位仪测量根尖受破坏牙齿工作长度的准确性.方法 将53颗离体牙沿釉牙骨质界截冠、去髓,根管预备到25#,使用Root ZX(A组),Propex(B组),Justy Ⅱ(C组)和 Raypex5(D组) 4种根尖定位仪分别测量每个根管的工作长度;再使用超声倒预备工作尖将以上各牙沿根尖孔破坏根尖狭窄部,再次用4种根尖定位仪测量工作长度.结果 所得数据与解剖镜下测量的实际数据进行比较,根尖完整时A、B、C、D4组数据在-0.5～0.5 mm误差范围内的百分数分别为86.3%、88.8%、85.0%、88.8%.根尖破坏时A、B、C、D4组数据在-0.5～0.5 mm误差范围内的百分数分别为16.7%、20.5%、10.3%、48.7%,在-1～1 mm误差范围内的百分数分别为74.4%、52.6%、57.7%、91.0%.结论 4种根尖定位仪对于根尖破坏的牙齿测量准确性比根尖完整的牙齿要低,相比之下Raypex5的准确性比较高.     

Ex vivo accuracy of three electronic apex locators: Root ZX, Elements Diagnostic Unit and Apex Locator and ProPex

AIM: To compare ex vivo the accuracy of three electronic apex locators (EALs): Root ZX, Elements Diagnostic Unit and Apex Locator and ProPex. METHODOLOGY: Electronic working length determination was carried out in 40 extracted teeth using an ex vivo model. After access preparation, a first operator determined the reference length (AL) for each tooth under a 30x stereomicroscope using the apical constriction as the apical landmark. All teeth were then measured with each EAL and the results obtained were compared with the corresponding AL. The AL was subtracted from the electronically determined distance. The measurements exceeding the AL were recorded as positive (long) and the measurements short of the AL were recorded as negative. Data were analyzed using the Friedman Test and Tukey multiple range test for nonparametric correlation amongst groups. Statistical significance was considered at P < 0.05. RESULTS: Comparing the differences between measurements obtained with the three EALs and those obtained with the stereomicroscope, the percentage of measurements within +/-0.5 mm of the AL was 97.37% (84.22% within 0.5 mm short of AL) for the Root ZX, 94.28% (88.57% within 0.5 mm short of AL) for the Elements and 100% (35.9% within 0.5 mm short of AL) for the ProPex. The mean difference between the AL and the lengths measured by the Root ZX, the Elements and the ProPex were, respectively, -0.157 +/- 0.228, -0.103 +/- 0.359 and 0.307 +/- 0.271 mm. CONCLUSIONS: The results of the present study confirm that the EALs determined the canal length within +/-0.5 mm from the apical constriction in the majority of cases. The majority of the ProPex readings were long.     

In vitro evaluation of the accuracy of five different electronic apex locators for determining the working length of endodontically retreated teeth

The aim of this study was to evaluate the accuracy of five electronic apex locators (EALs) in determining the working length (WL) of teeth after removal of the root canal obturation materials. A total of 32 extracted straight, single-rooted teeth were used. The actual canal length (AL) was determined and the WL was established by subtracting 0.5 mm from the AL. The root canals were instrumented and divided into two groups. One group (n = 6) served as control, while the other group (n = 26) was the experimental group. In the experimental group, the root canals were obturated using vertically compacted gutta-percha with AH 26 sealer. In both groups, the access cavities were restored with a provisional restoration and stored for 15 days at 37 degrees C and 100% humidity. The root canal obturation material was removed, and the teeth were then mounted in an experimental apparatus. Five EALs were used: Dentaport ZX, ProPex, Foramatron D10, Apex NRG and Apit 7. For the electronic measurement of canal length, a size 25 K-file was used. During measurement, the canal was irrigated with 2.5% sodium hypochlorite. The difference (D) between the AL and the electronically determined length (EDL), AL-EDL, was calculated and recorded for each measurement. Data were analysed by two-way anova and Fisher's PLSD test. In both groups, statistically significant differences were found among the EALs (P < 0.01). In conclusion, the Dentaport ZX, ProPex and Foramatron D10 were more accurate than the other two EALs in determining the WL in teeth after removal of the root canal obturation materials. However, the Apex NRG and Apit 7 were also reliable for determination of the WL in the majority of the cases.     

Accuracy of electronic apex locators using heat-treated Ni-Ti file

This study investigated the accuracy of two electronic apex locators (DentaPort and Bingo) using heat-treated nickel-titanium files. The true root canal length of 30 single-rooted teeth was determined using K files. Next, the electronically measured length was determined using two nickel-titanium files (ProGlider and HyFlex EDM Glide Path File) with two electronic apex locators at the ‘APEX’ marks. The accuracy of the electronic apex locator was evaluated by comparing the true root canal length and electronically measured length for each measurement. There was no significant difference between the measurements with two nickel-titanium files, and all differences between true root canal length and electronically measured length were within ±0.5 mm regardless of the type of nickel-titanium files or electronic apex locators. Based on the results, the heat treatment of the nickel-titanium files showed no adverse effects on the working length determination using electronic apex locators.     

ROOT ZX根尖定位仪在乳牙根管测量中的应用

目的:探讨ROOTZX根尖定位仪测量乳牙根管长度的精确性。方法:选择3 8例拟行根管治疗的4～6岁儿童,共65个乳牙(乳切牙2 5个、乳磨牙40个、共计160个根管) ,采用ROOTZX测量根管工作长度,按此长度充填根管,拍摄X线根尖片。结果:ROOTZX测量结果与X线根尖片显示根管充填长度相等或偏短,这个结果不受牙齿形态、根管形态、根尖周情况的影响(P >0 .0 5 )。结论:ROOTZX可用于乳牙根管长度的测量,特别适用于有牙科畏惧症、躁动不安的儿童。     

The fundamental operating principles of electronic root canal length measurement devices

It is generally accepted that root canal treatment procedures should be confined within the root canal system. To achieve this objective the canal terminus must be detected accurately during canal preparation and precise control of working length during the process must be maintained. Several techniques have been used for determining the apical canal terminus including electronic methods. However, the fundamental electronic operating principles and classification of the electronic devices used in this method are often unknown and a matter of controversy. The basic assumption with all electronic length measuring devices is that human tissues have certain characteristics that can be modelled by a combination of electrical components. Therefore, by measuring the electrical properties of the model, such as resistance and impedance, it should be possible to detect the canal terminus. The root canal system is surrounded by dentine and cementum that are insulators to electrical current. At the minor apical foramen, however, there is a small hole in which conductive materials within the canal space (tissue, fluid) are electrically connected to the periodontal ligament that is itself a conductor of electric current. Thus, dentine, along with tissue and fluid inside the canal, forms a resistor, the value of which depends on their dimensions, and their inherent resistivity. When an endodontic file penetrates inside the canal and approaches the minor apical foramen, the resistance between the endodontic file and the foramen decreases, because the effective length of the resistive material (dentine, tissue, fluid) decreases. As well as resistive properties, the structure of the tooth root has capacitive characteristics. Therefore, various electronic methods have been developed that use a variety of other principles to detect the canal terminus. Whilst the simplest devices measure resistance, other devices measure impedance using either high frequency, two frequencies, or multiple frequencies. In addition, some systems use low frequency oscillation and/or a voltage gradient method to detect the canal terminus. The aim of this review was to clarify the fundamental operating principles of the different types of electronic systems that claim to measure canal length.