Evaluation of the Efficacy of Different Systems in Determination of Root Canal Working Length: A Comparative Study

INTRODUCTION

The success of endodontic therapy is determined by locating all the radicular canals appropriately followed by largely effective elimination of the non-pathogenic and pathogenic bacteria. To attain this objective, it is essential to determine the working length (WL) of the root canals, which also is an estimate; essential for the subsequent treatment stages. Infected root canals, as well as periapical infection, may also result from inadequate length of the finished obturation. Precisely determining the WL avoids shorter length instrumentation that is inadequate to eliminate periapical infected tissues and microflora. The risk of excess length instrumentation is also deterred as this would otherwise lead to patient distress, injury to periapical tissues or can lead to an infection/cystic transformation due to over-obturation with toxic substance outside the apical region.¹

The essential prerequisites for perfect determination of the endodontic WL include precisely locating the apical limitations in various pulpal circumstances as well as the contents of the canal, ease of performing the measurements even in the presence of an abnormal relation amid apical constriction and apex as determined radiographically, agile cyclic observations and affirmations; the comfort of both the dental clinician and the patient, less radiation exposure of the patient, simplicity of use in a special group of patients and being economical.²

Combining various techniques helps attain the greatest level of preciseness in WL estimation. Due to ease and practical efficiency, a minority of clinicians still employ the tactile perception method in endodontic practice. Unfortunately, this methodology is generally not accurate in radicular canals with an immature apex, extreme curvatures and in case the canal is slender and contracted throughout its course.³

As technology advanced in leaps and bounds, the utility of digital radiography became profound and permitted a noteworthy reduction in exposure time and dose of radiation, as well as decreased time for image processing offering faster endodontic therapy. Though radiography allows numerous advantages like direct inspection of compound radicular canal anatomy, curvatures of canals, and presence of periapical pathosis, there is a drawback of the associated radiation exposure. To defeat such drawbacks, electronic apex locators (EALs) are being used in clinical practice to establish file location in the canal by determining apical constriction.⁴

Electronic apex locators offer multiple benefits such as a decrease in radiation exposure and treatment time, either of which helps maintain the cooperation of the patient. They may also be utilized to determine small constrictions. Microscopic researches have determined that apical constriction is present about 0.5–1 mm from the main foramen.⁵ Moreover, this indicates cases where the apical foramen is at some distance from the radiographic apex and might help detect root canal perforations. Hence, this research was undertaken to comparatively assess the diagnostic efficiency of four methodologies that is the tactile method, digital radiographic method, EAL method, and endodontic motor with incorporated apex locater in the estimation of root canal WL.

MATERIALS AND METHODS

RESULTS

Table 1 depicts κ values for the two observers that are in harmony with one another to a very short degree for the WLs calculated employing the tactile technique (0.013 and p value 0.941), digital radiograph (0.218 and p value 0.360), EAL (0.572 and p value 0.410), as well as an endodontic motor with an incorporated apex locator (0.724 and p value 0.386). The values delineated a κ value with a cent percent coincidence interval amid the two observers without significant disparity.

Table 2 demonstrates the evaluation of mean radicular length dimensions with different WL estimation techniques. The WL calculated by the tactile method was 20.42 ± 1.002, the digital radiographic technique was 20.74 ± 1.030, EAL was 21.56 ± 0.862, and endodontic motor with incorporated apex locator was 20.96 ± 1.010.

Table 3 shows the contrast of mean radicular length among different WL estimation techniques. The WL measurements with an EAL (21.56 ± 0.862) had more or less satisfactory coincidence with the actual WL (21.84 ± 0.486), pursued by endodontic motor with an incorporated apex locator (20.96 ± 1.010), digital radiographic technique (20.74 ± 1.030), and tactile means (20.42 ± 1.002). However, the difference between these experimental groups was not significant statistically.

DISCUSSION

Establishing the apical extent of root canal preparation is a vital stage of endodontic therapy. It is a general opinion that the root canal preparation and obturation must be within the confines of the canal. Hence, precise estimation of the WL is one of the highly significant steps in root canal treatment.⁶

Radiographs have been the sole, unanimously recognized, accessible, and important technique of adequately determining the WL in clinical practice. Nevertheless, this calls for repetitive exposure to undesired radiation before, during, and soon after root canal therapy. Radiation may have untoward effects on regions in way of the ionizing radiation which includes the oral and periodontal tissues, embryos, and fetuses in child-bearing women.⁷ Thus, decreasing the number of radiographs is critical to avoid recurring exposure of patients to ionizing radiation.

Previous findings by Kuttler⁸ demonstrate that a file tip 1 mm less than the actual apex, is well within the region where the apical constricted is usually situated. Nevertheless, it was felt suitable to deduct 0.5 mm from the tooth length of every tooth to estimate the definitive length, according to the research by Leddy et al.⁹ This study observed that the value determined by the electronic technique was within 0.5 mm of the definitive WL that can be accepted clinically.

0.5 mm of, actual working according to one other study by Ehsan,¹⁰ a correlation of measured values from radiographic and electronic techniques for WL estimation with directly noted visible lengths of radicular canals was evaluated. The root canal length was calculated via the Root ZX apex locator. This tool was able to estimate the length to within 0.5 mm of the apical constriction with 94.1% accurateness in contrast with the 50.4% precision of digital radiographs. Singh et al.¹¹ also procured comparable findings authenticating the electronic technique for WL measurement of root canals, which were more precise when compared with the radiographic method. The main advantages of EALs include reduction in radiation dosage and procedure time, both of which aid in maintaining patient cooperation. The EALs are used to locate the minor constriction.

In this research, it was noted that the WL measurements by the EAL were nearer to the definitive WL. This observation was in harmony with numerous studies documented by Kielbassa et al.¹² and Subramaniam et al.¹³ which cite the accuracy of the electronic technique in determining the WL when compared with the radiographic method.

Venturi and Breschi¹⁴ documented that the exactness of the EAL was better than radiographs. In vivo research documented by Vieyra and Acosta¹⁵ previously, cited that calculating the position of the apical constriction employing Root ZX apex locator was further precise than radiography, decreasing the peril of instrumentation and obturation ahead of the apex. As Root ZX mini incorporates the industry Root ZX technique working on a similar principle, Root ZX mini can gauge in either wet or dry canal environment. In addition, the small dimension of the Root ZX mini is advantageous in routine clinical practice.¹⁶

Root canal WL through EAL measurements indicated they were closer to the actual WL than those obtained from endodontic motor with integrated apex locator, digital radiograph, and tactile methods. The establishment of a correct WL is one of the fundamental parameters for endodontic success. Instrumentation that is too short of or goes beyond the apical foramen will adversely affect its success.

This research has few limitations. Bigger sample size could have enhanced the capacity to more precisely evaluate the importance of the consequences. As the EAL enhances the safety and ease of root canal treatment, its utilization must be assessed further in clinical studies. The difficulties encountered in the clinical setting, within the mouth to determine the WL may not be simulated in an in vitro model.

CONCLUSION

This study has some limitations, within which it may be concluded that the WL of root canals as estimated by the EAL implicated that these values were nearer to the actual WL than the values procured from endodontic motor with incorporated apex locator, digital radiograph, and tactile techniques.

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