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ORIGINAL ARTICLE
Year : 2011  |  Volume : 29  |  Issue : 4  |  Page : 300-304
 

Comparison of digital radiography and apex locator with the conventional method in root length determination of primary teeth


1 Department of Pedodontics and Preventive Dentistry, College of Dental Sciences, Davangere, Karnataka, India
2 D. A. Pandu Memorial Rashtriya vidyaniketana, Bangalore, Karnataka, India

Date of Web Publication21-Oct-2011

Correspondence Address:
I E Neena
Department of Pedodontics and Preventive Dentistry, College of Dental Sciences,Pavillion Road, Davangere - 577004, Karnataka
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0970-4388.86371

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   Abstract 

Aim: The purpose of this study was to compare the Working length in primary teeth endodontics using intra oral digital radiovisiography and apex locator with conventional method for accuracy. Materials and Methods: This in vivo study was conducted on 30 primary teeth which were indicated for pulpectomy in the patients of the age group of 5-11 years All experimental teeth had adequate remaining tooth structure for rubber dam isolation and radiographicaly visible canals. Endodontic treatment was required due to irreversible pulpitis or pulp necrosis. A standardized intraoral periapical radiograph of the tooth was taken using conventional method by paralleling technique. The distance between the source and the tooth, tooth and the films were standardized using X-ray positioning device. During the pulpectomy procedure, the working length was determined by digital radiograph and apex locator. The measurements were then compared with the conventional method of root canal measurement technique for accuracy Result: From the results obtained we can conclude that Working length determined in primary molars using digital radiography and Apex locator did not show any significant difference in the mean working length measurements when compared with the conventional radiographic method. Conclusions: Apex locator is comparable to conventional radiograph in determining the working length without radiation in the primary teeth. Intraoral digital radiography is the safest method in determining the working length with significant reduction in radiation exposure.Hence, both the techniques can be safely used as alternatives to conventional radiographic methods in determining working length in primary teeth.


Keywords: Apex locator, conventional radiography, digital radiography, primary teeth, working length


How to cite this article:
Neena I E, Ananthraj A, Praveen P, Karthik V, Rani P. Comparison of digital radiography and apex locator with the conventional method in root length determination of primary teeth. J Indian Soc Pedod Prev Dent 2011;29:300-4

How to cite this URL:
Neena I E, Ananthraj A, Praveen P, Karthik V, Rani P. Comparison of digital radiography and apex locator with the conventional method in root length determination of primary teeth. J Indian Soc Pedod Prev Dent [serial online] 2011 [cited 2018 Dec 14];29:300-4. Available from: http://www.jisppd.com/text.asp?2011/29/4/300/86371



   Introduction Top


Pediatric endodontics deals with the management of pulpally involved primary and young permanent teeth in children. Maintaining the integrity and health of the oral tissues is the primary objectives of pulp treatment. It is desirable to attempt to maintain pulp vitality wherever possible. [1] In permanent teeth, definitive rules for successful endodontic therapy have been established such as compact obturation and apical/coronal seal. In contrast, in pediatric endodontics, because of open apices, there are difficulties in estimating the exact root canal length, and hence, there are no definitive rules for successful endodontic therapy. [2]

Root canal length (working length, root length, tooth length) determination is an important step in root canal therapy. These terms are used interchangeably; however, they refer to the distance from the coronal reference point to the point at which canal preparation and obturation should terminate. Correct working length determination is one of the main factors leading to success in root canal treatment. Endodontic anatomy of primary teeth, in particular of molars is difficult to predict because the resorption of the roots causes the shape, dimension and position of the root apex to change continuously. This makes it difficult to determine the exact location of the actual apex. To minimize periapical injury and possible damage to the succedaneous tooth, the root length should be carefully determined without exceeding the apex. [3]

Radiographic method described by Ingle is one of the most common and reliable methods used in determining the working length; however, accuracy is difficult to achieve. In this technique, because of the apical constriction which cannot be identified, and the other variables, such as angulations of the machine and exposure, distortion of the image may occur, and lead to error. In addition, there is a radiation hazard, both, to the patient and the dental personnel. The observers' bias in radiographic interpretation may lead to errors. [4]

Technological advances have led to the introduction of digital radiology (DR), which has many potential benefits in endodontic practice. In dentistry, the first commercial integrated digital imaging system was radiovisiography, involving the use of an intraoral sensor instead of the conventional X-ray film. The radiovisiography allowed a substantial reduction in the duration of endodontic procedures, because it effectively eliminated the film-processing time. In the same way, the zoom function had the potential to improve the diagnostic performance by magnifying areas such as the apical zone. Digital imaging incorporates computer technology in the capture, display, enhancement, and storage of direct radiographic images. It also offers some distinct advantages over the conventional film; however, like any emerging technology, it presents new and different challenges for the practitioner to overcome. The other advantage of digital intraoral radiograph is the reduction of radiation dosage by up to 22% of F speed film. Digital radiography requires only approximately 23% of the x-ray dosage for a D speed film. [5]

A new equipment called Apex locator was introduced by Sunada in 1962 to locate the root apex for measuring the root canal length. Main advantages of apex locators are that these measure the root canal length to apical foramen, not the radiographic apex. They are easy and fast to operate, and have a good accuracy. Artificial perforations can be recognized and radiation to the patient can be reduced. The purpose of the present study is to compare the working length determined by digital radiography and Apex locator with that of a conventional radiograph for accuracy.


   Materials and Methods Top


This in vivo study was conducted on 30 primary teeth which were indicated for pulpectomy in the patients of the age group of 5-11 years in the Department of Pediatric and Preventive Dentistry, D.A. Pandu Memorial Rashtria vidyaniketana Dental College Bangalore. Children were selected according to the inclusion criteria after obtaining consent from the parents. All experimental teeth had adequate remaining tooth structure for rubber dam isolation and radiographically visible canals. Endodontic treatment was required due to irreversible pulpitis or pulp necrosis. A standardized intraoral periapical radiograph of the tooth was taken using conventional method by paralleling technique. The distance between the source and the tooth; and, the tooth and the films, was standardized using X-ray positioning device.

After administration of block with Lignocaine local anesthesia with adrenaline, tooth was isolated with rubber dam. Access cavity preparation was done using a round diamond bur under abundant water spray. Pulpal tissue of each tooth was extirpated using a barbed broach, and the root canals were irrigated using sodium hypochlorite solution. The pulp chamber was dried using sterile cotton pellets. Measurements from the preoperative radiographs were made using ISO 15-20 number files with rubber markers, keeping them 0.5 mm short of the root apex. With these measurements, the files were inserted into the canal and a conventional radiograph was taken. Using the same measurement, the files were then again placed in the canals, and an intraoral digital radiograph was taken. The root canal length was clinically determined with the help of an electronic apex locator. The file was attached to the file holder and the lip clip was attached to patients lip. The file was advanced till the device indicated that the apical constriction had been reached. The root lengths estimated from intraoral digital radiography and apex locator were compared with the conventional method of root canal measurements for accuracy. Measurements were subjected to statistical analysis using Analysis of Variance .

The present study showed that Mean of apex locator was 11.79, conventional radiograph was 11.76 and digital radiography was 11.98 as shown in [Table 1], we notice that there is no significant difference in the mean root length measurements from the three techniques (P > 0.05) [Table 2] and [Table 3].
Table 1: Descriptive statistics of root length (mm)

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Table 2: Analysis of variance root length (mm)

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Table 3: Proximity matrix

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Totally 90 canals' (30 teeth) measurements were taken in this study. Mean of apex locator was 11.79, conventional radiograph was 11.76 and digital radiography was 11.98. The above ANOVA table shows the sum of squares between groups as 2.585, within group as 761.367, and, degree of freedom between group as 2 and within group as 267. From the above ANOVA table we notice that there is no significant difference in the mean root length measurements from the three techniques (P > 0.05). We observe that the above proximity table shows that the distance between apex locator and conventional radiograph is low compared to the distance between intra oral digital radiovisiography and conventional radiograph.


   Discussion Top


The establishment of the apical limit of canal preparation is an important phase of root canal treatment. It is generally accepted that canal preparation and filling should be limited within the root canal. [6] Thus, accurate determination of the root canal working length is one of the most important steps in endodontic therapy. Conventional radiographs are needed before, during and immediately after the endodontic treatment and then periodically to evaluate the success or failure of the therapy. Hence, there is repeated exposure to unwanted dosage of radiations. Numerous animal and human investigations have studied the adverse effects of radiation on areas in the path of ionizing radiation. These areas include the oral tissues, perioral tissues, head and neck regions, human embryos and fetuses in pregnant women. [7]

Conventional radiography as a method of determining the working length has numerous short comings in that it depends on the child's co-operation, as well as the operator's proficiency. In addition to this, minor degrees of resorption may not be visible, and overlapping by adjacent anatomical structures can obscure the clarity of the image. [8] The other important problem associated with intra oral periapical radiograph is the positioning of the film inside the mouth. Error in placement of film and x-ray cone was eliminated by the design of the positioning apparatus, which allowed the fixation of the x-ray cone and reproducible placements of the experimental films and sensor. [9] The other problem associated with intra oral periapical radiograph is developing, fixing, drying and storage of the film.

The above problems associated with conventional radiographs were overcome with the introduction of intra oral digital radiograph. A number of fundamental issues need to be resolved before digital radiology can be fully incorporated into clinical practice (Van Der Stelt 1995). The radiological diagnostic techniques used in the present study were chosen to reflect current interests in comparing the performances of digital and conventional radiology, and assessing their applicability to root canal measurements. [4] It has been reported that intraoral digital radiography has provided approximately 60% reduction in radiation dosage in comparison with conventional radiography. [6] It also permits immediate display of image, image enhancement, storage, retrieval and transmission. [10] Other advantage include ease of repetition and the elimination of chemical usage. It also reduces the need for a dark room, films, mounts and processing equipment. The radiovisiographic images appear instantly on the monitor screen after exposure of the sensor image; and can be used for patient education directly. Decreased exposure time also allows lower radiation dosage and reduces chair side time. Studies have shown that intra oral digital radiograph can be safely used in measurements of root length in root canal treatment.

Main disadvantage of intraoral digital radiography includes the cost of the equipment. Similar to conventional radiography, placement of sensor in the child's mouth is a difficult task. Another possibility is the magnification of the actual images, in the images obtained by intraoral digital radiography.

In the present study, D-Speed film was used because they are still the most widely used intraoral films. This was thus similar to the study conducted by E.Y. Ong and T.R. Pitt ford, where they have used D-Speed films. Studies have shown no difference in clinical image quality between D and E-Speed films. [2] Introduction of electronic methods for root length determination without using radiovisiography has helped in overcoming problems associated with intraoral digital radiographs. Many studies report on the accuracy achieved by the new generation of electronic apex locators as well, as they now have extended measurement capabilities, and provide accurate measurements in the presence of electrolytes. Moreover, it has been reported that radiographic methods for tooth length determination might be less accurate than the electronic methods, and the latter are extremely useful in children who gag during radiography. [11]

The first generation apex locators used the resistance method and measured opposition to the flow of direct current. Here, the patients experienced pain and discomfort due to the high current in the original machine. The second generation apex locators, also known as Impedance apex locators, measure opposition to the flow of alternating current or impedance. Major disadvantage of this generation of apex locators is that the canal has to be reasonably free of electro conductive materials to obtain accurate readings. Third generation apex locators are based on frequency dependence. The disadvantages include sensitivity to canal fluid and the machine needs a fully charged battery. Dual frequency alternating current signals are now utilized to perform measurements automatically, without the need for calibrations. They have an advantage that they can be used in both, wet and dry environments.

In the present study, fifth generation apex locator was used which works on dual frequency type, and is considered best in any root canal condition. It provides the reader with a digital read out, graphic illustration and an audible signal. Main advantage of apex locators is that they measure the root canal length to the apical foramen, not to the radiographic apex. They are easy and fast to operate and give good accurate results. Artificial perforations can be recognized and radiation to the patient can be reduced. [12] It is also emphasized that the use of apex locator alone without the preoperative and postoperative radiographs is not a recommended practice due to the large number of variations in the tooth morphology, and medico legal record keeping requirements. [13]

The present study on root length determination was done using intraoral digital radiograph and apex locator, which was then compared with the conventional radiograph. In this study, 30 primary teeth were taken which would give a statistical significant result and patients selected were in the age group of 5-11 years as they would be having 2/3 rd of the root length. Files selected to measure working length were in of the number 15-20, similar to the study conducted by Ssu-Kuang Chen et al. where they have used files of 15-20 size. This is because the tips of the No 10K files were not identifiable as the tip diameter is less than 120 micron meter required.

A study by Velders et al. showed that a size # 15 should be the threshold file size for length measurements and concluded that lengths of size 25 and 20 file in digital images was comparable with the lengths on the conventional film. Another study using density profile plot analysis for digital images noted that file lengths decreased perceptibility with sizes # 15 and #10, therefore a size 20 file was chosen for radiographic length determination of true canal length in this study. [14] Various studies have been carried out where there have been numerous technique employed in working length determination including radiography, apex locator, tactile perception, average tooth length and paper points; however, reliability and reproducibility of conventional films have made them gold standard by which all imaging systems are compared. [15]

In our study, although there was no significant difference between the two modalities and the gold standard conventional radiographic method, measurements made from the direct digital images showed around 1.86% of magnification compared with that of conventional method and apex locator. This can be seen in other studies where direct digital radiograph has shown over prediction of the working length. One possible explanation may have been the lack of a reference point on the occlusal surface of the teeth from which measurements were made. In this study, although there was no significant difference in the mean root length measurements from the three techniques, it was observed that apex locator yields similar measurements to conventional radiograph.

In the present study, D- Speed film was used for conventional radiographic method. Another study conducted using D and F Speed intraoral radiographs, and digital and enhanced digital radiographic images for endodontic file length determination, showed no significant difference among the four image types. [9] Hence, the results coinside with our study in the use of film speed, and the accuracy in working length determination. In the present study, intra oral digital radiovisiography showed 1.86% of over prediction, it may be due to magnification errors caused by positioning of the sensor, inspite of using position indicating devices due to the lack of correct reference point. Thus, similar studies need to be conducted on larger samples to find out the cause of over prediction in working length determination using intra oral digital radiography.

From the results obtained, we can conclude that intraoral digital radiography and apex locator methods of determining the root canal length in primary teeth can be considered as reliable and safe methods in the endodontic treatment of children.


   Conclusions Top


The following conclusions were drawn from this present study:

  • Apex locator is comparable to conventional radiograph in determining the working length without radiation in the primary teeth;
  • Intraoral digital radiography is the safest method in determining the working length with significant reduction in radiation exposure.
Hence, both the techniques can be safely used as alternatives to conventional radiographic methods in determining working length in primary teeth.

 
   References Top

1.Tosun G, Erdemir A, Eldeniz AU, Sermet U, Sener Y. Accuracy of two electronic apex locators in primary teeth with and without apical resorption: A laboratory study. Int Endod J 2008;10:365-71.  Back to cited text no. 1
    
2.Kielbassa AM, Muller U, Munz I, Monting JS. Clinical evaluation of the measuring accuracy of ROOT ZX in primary teeth. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2003;95:94-100.  Back to cited text no. 2
    
3.Kumar SS, Chacko Y, Lakshminarayanan L. A simple model to demonstrate the working of electronic apex locators. Endodontology 2004;16:50-3.  Back to cited text no. 3
    
4.Lozano A, Forner L, Liena C. In vitro comparison of root canal measurements with conventional and digital radiology. Int Endod J 2002;35:542-50.  Back to cited text no. 4
    
5.Parks ET, Williamson GF. Digital Radiography: An Overview. J Contemp Dent Pract 2002;3:36-40.  Back to cited text no. 5
    
6.Melius B, Jiang J, Zhu Q. Measurement of the Distance Between the Minor Foramen and the Anatomic Apex by Digital and Conventional Radiography; Journal Of Endodontics. 2001;65(10):985-990.  Back to cited text no. 6
    
7.Yousef saad A, saad Al-Nazhan.Radiation dose reduction during endodontic therapy: A new technique in combining apex locator and a digital imaging system. J Endod 2000;26:144-7.  Back to cited text no. 7
    
8.Herrera M, Abalos C, Planas AJ, Llamas R. Influence of apical constriction diameter on Root ZX apex locator precision. J Endod 2007;33:995-8.  Back to cited text no. 8
    
9.Radel RT, Goodell GG, McClanahan, Scott B, Cohen ME. In vitro Radiographic Determination of Distance from Working Length Files to Root Ends Comparing Kodak RVG 6000. Schick CDR, and Kodak Insight Film. Basic Research -Technology; 2006. p. 566-8.  Back to cited text no. 9
    
10.Gordon MP, Chandler NP. Electronic apex locators. Int Endod J 2004;37:425-37.  Back to cited text no. 10
    
11.Al-Nazhan S, Al Yahya AS, Al-Hindi M. Evaluating the accuracy of an electronic root canal measuring device using the clear technique. Saudi Dent J 1993;5:132-5.   Back to cited text no. 11
    
12.Lamus F, Katz JO, Glaros AG. Evaluation of a digital measurement tool to estimate working length in endodontics. J Contemp Dent Pract 2001;2:24-30.  Back to cited text no. 12
    
13.Grimberg F, Banegas G, Chiacchio L, Zmener O. In vivo determination of root canal length: A preliminary report using the Tri Auto ZX apex-locating handpiece. Int Endod J 2002;35:590-3.  Back to cited text no. 13
    
14.Hör D, Krusy S, Attin T. Ex vivo comparison of two electronic apex locators with different scales and frequencies. Int Endod J 2005;38:855-9.  Back to cited text no. 14
    
15.Leonardo MR, Silva LA, Nelson-Filho P, Silva RA, Raffaini MS. Ex vivo evaluation of the accuracy of two electronic apex locators during root canal length determination in primary teeth. Int Endod J 2008;41:317-21.  Back to cited text no. 15
    



 
 
    Tables

  [Table 1], [Table 2], [Table 3]


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