Comparison of Accuracy of 3 Different Methods of Working Length Determination in Lower Premolars In-Vivo and by using CBCT and Magnifying Loupe Ex-Vivo

COMPARISON OF ACCURACY OF 3 DIFFERENT METHODS OF WORKING LENGTH DETERMINATION IN LOWER PREMOLARS IN-VIVO AND BY USING

CBCT AND MAGNIFYING LOUPE EX-VIVO

A dissertation submitted

In partial fulfillment of the requirements For the degree of

MASTER OF DENTAL SURGERY

BRANCH IV

CONSERVATIVE DENTISTRY AND ENDODONTICS

THE TAMILNADU DR.M.G.R. MEDICAL UNIVERSITY CHENNAI 600032

"No one who achieves success does so without acknowledging the help of others. The wise and confident acknowledge this help with gratitude."

Foremost, I want to offer this endeavour to The Almighty, for the wisdom he has bestowed upon me, the strength and good health in order to finish this dissertation.

I thank our Chairman Prof. Dr. K. R. Arumugam, & Vice Chairman A. Babu Dhandapani for the facilities provided to carry out the work at the Institute.

I extend my sincere gratitude to our respected Principal Prof. Dr. K.S. Prem Kumar M.D.S, Head of the Department of Orthodontics, for allowing me to perform my study in orthodontic patients and also for his support.

I am grateful to Prof. Dr. P. Hemalatha M.D.S., Head of the Department of Conservative Dentistry and Endodontics, for her invaluable guidance. I thank her for having trust in me and providing me with this wonderful clinical study. It was a great privilege to work and perform the study under her supervision.

Acknowledgement

I shall always be indebted to all the Teachers and PGs of the Department of Orthodontics and the Department of Oral and Maxillofacial Surgery for the timely help rendered by them throughout the study period.

My profound gratitude to my other Fellow Post Graduates for their valuable support and

togetherness. A very special thanks to my juniors Dr.D.S. Venkataramanan and Dr. G. Sudharsan for helping me by being the second observers in this dissertation.

I owe my sincere gratitude to Dr. Sangeetha Chavan M.D.S. Reader, Department of Community and Public Health Dentistry and to my dear friend, Dr. Vidhya Raghu for their great support in the biostatistics and helped me to present my results in a very unique way.

No research is possible without The Library, the Centre of learning resources. I take this time to express my gratitude to the library staffs for their great support.

Above ground, I am indebted to my family, My Parents and My Sister whose values helped me to only grow with age. And finally, I acknowledge My Husband and My Lovely Daughter who served as my inspiration to pursue this undertaking.

AIM:

The aim of the study was to determine the accuracy of working length determination using Tactile Sensation method, Digital Radiographic Method (RVG) and Electronic Apex Locator (PROPEX II) in lower premolars in-vivo, and to compare the lengths so measured to the actual working length after extraction, measured using CBCT and Magnifying Loupe, ex-vivo.

MATERIALS AND METHODS:

30 mandibular premolars scheduled for orthodontic extraction were selected. After informed consent from the patient, under local anaesthesia, access cavity was prepared, canal located and pulp extripated. The working length was determined by Tactile Sensation method, Digital Radiographic Method (Radiovisiography) and Electronic Apex Locator using PROPEX II apex locator. The values were measured and tabulated. All the 3 methods were performed by 2 operators after blinding. After determining the working length in vivo, the teeth were extracted and the samples were then subjected to Cone beam computed tomography and the CBCT working length was determined. Now a K- file was inserted into the root canal until the file tip is visible at the apical foramen which was confirmed using a Magnifying loupe and these readings were measured as the actual working length of the tooth. and cross evaluated with all other working length values. The reliability analysis was also done to analyze the level of reliability of each group with the Actual Working Length values obtained using Magnifying loupe after extraction.

RESULTS:

Abstract

measurement using CBCT and Electronic apex locator are the most reliable method followed by radiographic method and tactile sensation respectively. Based on the correlation values on reliability, CBCT method have more positive correlation with actual working length measured using Magnifying loupe, followed by Electronic apex locator and then by RVG and tactile sensation.

CONCLUSION:

Within the limitations of the present study, it is concluded that

1. Comparison of working that length measurement with Magnifying Loupe, CBCT, and other 3 conventional in vivo methods showed a significant difference in measurement. 2. Radiographic working length determination using RVG, can be considered as reliable tool

when combined and confirmed with electronic working length measurement.

3. The EAL values of working length showed more positive correlation with the AWL values measured using magnifying loupe. Keeping other potential advantages in consideration, we conclude that the use of EAL technique clinically is useful in root canal treatment for measuring working length which correlates more positively with the AWL.

4. CBCT scans can be used as an alternative method for ascertaining the WL. If a patient has a preexisting CBCT scan, the clinician should take advantage of this technique as an alternative, reliable method for determining the WL.

LIST OF ABBREVIATIONS

No. Acronym Abbreviation

1 CDJ Cemento-dentinal junction

2 AC Apical constriction

3 AF Apical foramen

4 IOPA Intra oral periapical radiography

5 RVG Radiovisiography

6 CCD Charge coupled device

7 CBCT Cone beam computed tomography

8 MPR Multiplanar reformation

9 FOV Field of view

10 CMOS Complementary metal oxide semiconductor

11 DDR Direct digital radiography

12 TWL Tactile working length

13 RWL Radiographic working length

14 EAL Electronic apex locator working length

15 OPG Orthopantamography

16 CBCTWL Cone beam computed tomography working length

17 PSP Photostimulable phosphor plate

18 EDTA Ethylene diamine tetra acidic acid

19 MDCT Multidetector computed tomography

20 SPSS Statistical package for the social sciences

LIST OF FIGURES

No.

Description of Figures

Page No.

1 Working mechanism of RVG 4

2 Working principle of EAL 7

3 Flat panel detectors in CBCT 11

4 Mechanism of image production in CBCT 12

5 Carl Zeiss magnifying loupe 190mm (8.0x) 14

6 Pre-operative OPG 36

7 (A) _{Consent form -English 39}

7 (B) Consent form - Tamil 39

8 Anatomy of the root apex 53

9 (A) Injection of Local Anesthesia 40

9 (B) Rubber dam isolation 40

9 (C) Access cavity preparation 40

10 Working length determination using Tactile

sensation method

41

11 Working length determination by RVG 42

12 Working length determination using electronic apex locator

43

14 Extracted premolar 44

15 CBCT model 44

16

CBCT working length measurement using

DICOM software

45

17 (A) Evaluation of AWL using magnifying loupe 46

17 (B) Position of the file tip at the minor diameter seen through the apical foramen

46

17 (C) Measurement using digital caliper 46

LIST OF TABLES

No.

Description of Table

Table 1

Classification of EAL by the type of current

involved

8

Table 2 Resistance type apex locators 8

Table 3 Impedance based apex locators 9

Table 4 Frequency based apex locators 9

Table 5 Armamentarium Materials used 37

Table 6 Armamentarium Instruments used 38

Table 7

Working length values measured by different

methods (mm)

48

Table 8 Inter-observer variability using Kappa test 49

Table 9

Repeated measured ANOVA with Post Hoc

Bonferroni Test

50

Table 10 Paired sample correlation percentage 51

Table 12 Studies of the position of the apical constriction 54

Table 13 Summary of various RVG studies

57

Table 14

Various comparative studies on different methods

of working length determination with EAL

TABLE OF CONTENTS

No.

Contents

Page No.

1

Introduction

1

2

Review of Literature

15

3

Aim and Objectives

35

4

Materials and Methods

36

5

Statistical Analysis

47

6

Results

48

7

Discussion

53

8

Summary

68

Introduction

1

The long-term success of root canal treatment depends upon the relationship between

instrumentation and obturation procedures and the complex anatomy of the apex.1 Determination of working length is one of the most critical steps of endodontic therapy and a

clear understanding of the morphology of the root canal system, including the apex, is

imperative. The cleaning, shaping and obturation of the root canal system cannot be

accomplished accurately unless the working length is determined precisely.2

WORKING LENGTH is defined in The distance

from a coronal reference point to the point at which canal preparation and obturation

The anatomical apex is the tip or the end of the root determined morphologically, whereas the

radiographic apex is the tip or the end of the root determined radiographically. It is well

established that root morphology, root aberrations, anatomical variations and radiographic

distortion may cause the location of the radiographic apex to vary from the anatomical apex. 3

The dentin cementum junction has been recommended as an ideal apical termination for root

canal preparation4. The position of this histologic entity varies around the internal

circumference of the canal by up to 3 mm across opposing walls. It is located approximately

1 mm away from the apical foramen.5

An apical constriction usually occurs in the region of the dentin cementum junction and

often forms a natural apical matrix. It is the narrowest portal of entry of the pulpal

vasculature from the periapical tissues and would be the smallest wound following pulp

removal. The topography of the apical constriction is variable and undetectable

2

Kuttler investigated the root apices of teeth and provided a dimensional analysis of the apical

morphology. He noted that the distance from the apical constriction to the vertex of the root

increased with age and was recorded as between 0.5 and 0.6 mm. This distance was

considered as a measurement to subtract from the radiographic apex to approximate the

location of the apical constriction.6 Working length, the apical extent of canal preparation and

obturation, is often the main variable in determining success or failure. Seltzer et al. were the

first to report greater success in terminating cleaning and obturating the root canal system just

short of the radiographic apex.7

Sjogren et al. investigated endodontic outcomes over an 8- to 10-year period in over 350

patients. They reported the best outcome was when the root canal filling was between 0 to 2

mm short of the radiographic apex. Distances beyond the radiographic apex, or more than 2

mm short of this point, resulted in significantly lower success rates. These findings are in

agreement with research conducted by other investigators and most recently by

meta-analysis of the literature.8

Chugal found variations in success rate of teeth root filled at different levels. Teeth with

normal preoperative pulps and periapical tissues enjoyed a higher success rate when filled

over 1 mm from the radiographic apex. On the other hand, teeth with necrotic pulps and

apical periodontitis showed greater success when the canal filling was closer to the level of

the radiographic apex. From all the evidence cited, it is clearly prudent to be able to

accurately prepare and fill root canals to a predetermined location in the canal short of the

Introduction

3

METHODS OF DETERMINING WORKING LENGTH:

The requirements of an ideal method for determining working length include rapid location

of the apical constriction in all pulpal conditions and all canal contents; easy measurement,

even when the relationship between the apical constriction and the radiographic apex is

unusual; rapid periodic monitoring and confirmation; patient and clinician comfort; minimal

radiation to the patient; ease of use in special patients such as those with severe gag reflex,

reduced mouth opening, pregnancy, pacemakers, implants etc, and cost effectiveness.10To achieve the highest degree of accuracy in working length determination, a combination of

several methods should be used. This is important in canals for which working length

determination is difficult11.

THE MOST COMMON METHODS ARE.

i. Patient Response.

ii. Tactile Sense Method

iii. Paper Point Measurement.

iv. Radiographic Methods.

v. Electronic Methods.

vi. Audiometric Method.

Of these methods 3 clinically more reliable methods - Tactile Sense Method, Radiographic

Method and Electronic Method have been chosen for this study.

TACTILE SENSATION METHOD:

The tactile perception because of the simplicity of the technique and its virtual effectiveness

are factors that motivate a few clinicians in endodontic practice to still follow this technique.

This method is considered as supplementary to high-quality, carefully aligned, parallel,

4

constricted, an experienced clinician may detect an increase in resistance as the file

approaches the apical 2 to 3 mm.12 Following access, when interferences in the coronal third of the canal are removed, the observant clinician can detect a sudden increase in resistance as

a small file approaches the apex. Careful study of the apical anatomy discloses two facts that

make tactile identification possible:

(1) the unresorbed canal commonly constricts just before exiting the root, and

(2) it frequently changes course in the last 2 to 3 mm.

The awareness of these variations may be enhanced by the use of a file that is larger than the

expected constricture. As preparation develops space in the coronal two-thirds (i.e., radicular

access), the quality of tactile information improves. At that point files bind only in the apical

area, and resistance must be in that region. 13Hence in this clinical study, tactile sense method is used to determine the working length in-vivo.

RADIO VISIO GRAPHY. (RVG)

One of the direct digital radiographic techniques used in dentistry is radio visiography (RVG)

which was introduced to dentistry by Francis Mouyen. This system is based on digital image

capture using a charged coupled device (CCD) which is capable of image enhancement using

up to 256 shades of gray.14

Introduction

5

By means of a solid-state radiation detector more sensitive than conventional silver halide

films, the system presents intra oral radiographic images immediately after exposures. One of

the advantage of this digital radiographic technique over conventional radiographs is the

possibility of quantifying the distance between two points on a given image. Ong et al in

1995 stated that RVG is the on -screen measurement utility which allows for rapid additive

multiple point measurement points on screen to a tenth of a millimeter. This is one of the

great advantages of the use of this system in endodontics. 15

In vitro study by Dina Al-Sudani 2002 showed that digital radiography is of equal value to

conventional radiograph for imaging root canal system. However, the radiovisiography has

the advantage of being rapid, low dose imaging technique, besides the image can be stored. 16 Other advantages of this digital technique include immediate image display, the ability to

improve the clarity of the image whilst reducing the radiation dose and accurate working

length estimation even in roots demonstrating severe apical curvature. Hence in this study

RVG has been selected as one of the methods for the in-vivo determination of working

length.17

DETERMINATION OF WORKING LENGTH BY ELECTRONICS

Electronic apex locators (EALs) have been one of the major breakthroughs in the traditional

practice of endodontics, as they operate on the electrical impedance at the apical foramina

rather than by a visual inspection of the radiographic apex. EALs are convenient for the

patient and operator, eliminate radiation exposure, save time, and can be used during

6

In 1918, CUSTER was the first to report the use of electric current to determine working

length

In 1942, SUZUKI, reported his study on iontophoresis of ammoniated silver nitrate in the

teeth of dogs. The silver solution was placed in the root canals and then totally dispersed by a

negative electrode in contact with the oral mucous membrane. The conclusion of this

experiment was that the electrical resistance between the root canal instrument inserted into a

root canal and an electrode applied to the oral mucous membrane registered a consistent

value of approximately 6.5 kilo ohms (kW).

In 1960, GORDON, was the second to report the use of clinical device for electrical

measurement of root canals.

In 1962, SUNADA, adopted the principle reported by Suzuki and was the first to describe the

detail of a simple device to measure working length in patients. He used a simple direct

current ohm meter to measure a constant resistance of 6.5 (kW) between oral mucous

membrane and periodontal ligament regardless of age of the patient or the shape and type of

the teeth which became the basis for most apex locators.18

circuit one side

the patients hand. The electrical circuit is complete when the endodontic instrument is

advanced apically inside the root canal touches the PDL. The display on the apex locator

Introduction

7

FIG 2: WORKING PRINCIPLE OF EAL

Classification20

The classification of apex locators was given by Mc Donald (1992)based on Type of current flow (operating principle)

8

Depending upon type of current involved

(Table 1)

Resistance type apex locators (Table 2): These apex locators has a built in resistance value

of 6.5 kilo Ohms. The apex locators are attached to the patient's lip on one side and the other

side is attached to the file. The file is then advanced into the canal until it touches the

periodontal tissue at the apex which then completes the circuit.

Impedance type apex locator (Table 3): Operate on the principle that there is electrical

impedance across the walls of the root canal due to the presence of the transparent dentin.

The tooth exhibits increasing electrical impedance across the walls of the root canal, which is

Introduction

9

unit detects the sudden change and indicates it on the analogue meter. To overcome the

problem of a wet environment, insulated probes are utilized.

Frequency based apex locators (Table 4): Operate very similarly to the impedance type

because it measures the impedance of tooth at two different frequencies. In the coronal

portion of the canal, the impedance difference between the frequencies is constant. As the file

advanced apically, the difference in the impedance value begins to differ greatly with

maximum differences at the apical area.

Propex II (Densply-Maillefer, Tulsa) apex locator was used in this study, as some

of the earlier studies in permanent teeth have found it to be better when compared with other

10

principle that uses multiple frequencies to determine the root canal length. Rather than using

the amplitude of the signal as for all EALs, it measures the energy of the signal with multi

signal frequencies. Hence, Propex II is reportedly less affected by potential interferences in

the root canal. Propex II works by calculating the ratio of the impedances measured

simultaneously at frequencies of 0.5 and 8.0 kHz.21

Endodontic Working Length Measurement with Cone-Beam

Computed Tomography Scanning

Cone-beam imaging, sometimes referred to as digital volume tomography, is one of the most

exciting developments in dental and maxillofacial radiology and, owing to its versatility.

CBCT allows the c

-dimensional images in the coronal, sagittal and even oblique or curved image planes a

process referred to as multiplanar reformation (MPR).Dental CBCT technology first emerged

in 1995 when Italian inventors Attilio Tacconi and Piero Mozzo introduced the first

maxillofacial imaging device, the NewTom DVT 9000. 22

Working mechanism:

Dental CBCT utilises a cone- or pyramid-shaped X-ray beam which is directed on the

pursued maxillofacial field-of-view (FOV). Most of the modern CBCT scanners use flat

panel detectors (FPD) comprising of a pixel array of amorphous silicon thin-film transistors

(TFT) or complementary metal oxide semiconductors (CMOS). For both of these, X-rays are

first converted to light photons by a scintillator material which may consist of thallium doped

caesium iodide (CsI:Tl) or terbium activated gadolinium oxysulphide (Gd2O2S:Tb).

Introduction

11

array to compile a projection raw-data digital image. Flat panel detectors offer higher spatial

resolution and greater dynamic range, and are less bulky and complicated compared to image

intensifiers (II) and charge coupled devices (CCD) which have gradually become obsolete as

CBCT detectors.23

FIG 3: FLAT PANEL DETECTORS IN CBCT

The pre-processing steps of the acquired projection raw-data vary between manufacturers for

flat-panel detectors. Typical steps include adjustments related to detector dark-current, gain

and pixel defects by applying offset and gain corrections.

A possible latent image signal from the previous projection read-out also has to be erased by

after glow correction, especially if higher frame-rates are applied. Other processing methods

can be utilised based on the physical properties of the acquisition system, such as X-ray beam

12

Once the X-ray measurements are acquired, they are transferred to a computer where they are

processed to obtain a image volume. This process is called image reconstruction. Once image reconstruction has been performed, the computer components of the system make the CT

image volume available for display in some sort of image viewing software.22

FIG 4:MECHANISM OF IMAGE PRODUCTION IN CBCT

In CBCT imaging, voxels are usually isotropic and range from 0.4 mm3 to as small as 0.075

mm3. This superior spatial resolution is one of the most attractive qualities of CBCT imaging

and is largely the result of flat panel technology and isotropic data acquisition. Small FOV

(55 mm_37 mm) CBCT with a 0.076-mm3 voxel size had the potential to improve the spatial

resolution of root canal anatomy in any chosen viewing plane. Working length measurements

obtained by different CBCT FOVs and voxels were clinically acceptable and correlated with

Introduction

13

Liang et al. 2013 found CBCT-based root-canal length measurements are accurate and

reliable, when compared with a gold standard, as actual length. In addition, Janner et al. in

2015 reported that an existing CBCT is as successful as an EAL. Connert et al. in 2016 found

69% accuracy with the CBCT, compared with AL, and concluded that CBCT images can be

used to accurately determine WL. 42

Ela Youti et al in 2009 described that in cases with inconsistent EAL measurements, the

possibility of obtaining root canal measurements from CBCT images could lead to a more

precise evaluation of working length and improved success rates for endodontic treatment.

On the other hand, teeth with metallic reconstructions are prone to problems with EAL

measurements because of electrical short circuits. For 3D imaging using computed

tomography, acquisition artifacts such as beam hardening, scatter, noise, and streak artifacts

caused by metal reconstructions have been described, with CBCT showing less prevalence of

this kind of image distortion. Hence this CBCT working length determination is taken as one

of the parameters in this study.25

Measurement of actual length of tooth after extraction using

Magnifying loupe:

The anatomical variables should be important for accurate working length determination.

The minor diameter of the canal represents the transition between the pulpal and the

periodontal tissues where the canal instrumentation and obturation should terminate.

Microscopic studies estimate the distance of the minor diameter to be from 0.5 to 1.0mm

from the external foramen or major diameter.

When the anatomic apex and apical foramen do not coincide, radiographic estimation of

working length becomes more questionable, and other methods of working length

determination become more important. The larger the distance between these two points, the

14

more significant when treating premolars and molars where there is a higher probability of

inconsistency in foramen position. It was demonstrated that the apical foramen is located

laterally in 78 to 93% of posterior teeth. 26

The actual working length measurement after extraction should be done by taking histologic

sections for locating the minor diameter. But the reliable and feasible method is by inserting

a file into the canal, until the tip can be seen through the major foramen and adjusted for its

position at the level of the coronal-most boundary of the major foramen. The visual

evaluation could be done using magnifying glass, stereomicroscope, surgical operating

microscope or using magnifying loupes.

The magnifying loupe used in this study has 8X magnification which gives an accurate

visualization of the file tip at the minor diameter with great precision. The actual length (AL)

of the tooth is considered as a gold standard in the present study and was measured after

evaluation under Magnifying loupe.27

15

1.

This comparative ex- vivo study was done to determine the accuracy in measuring the

working length of root canal using tactile method, electronic apex locator and radiographic

method, in vivo, and comparing the lengths so measured to the actual working length, ex

vivo, after extraction. Thirty single-rooted teeth scheduled for extraction were selected for the

study. After obtaining the consent from patients, a preoperative radiograph was taken and

access opening was done. Working length was determined by ta

radiographic method and by using a Foramatron-IV digital apex locator in vivo. The teeth

were then extracted and the actual working length was determined by placing an endodontic

file in the root canal 0.5 mm short of the apex. The results indicated that among the three

methods, the electronic apex locator showed the highest accuracy and the highest reliability

for working length determination.28

2.

The purpose of the present study was to compare the accuracy of frequency based apex

locator Root ZX and conventional radiographic method under clinical conditions. The

accuracy of the the working length by microprocessor controlled impedance quotient apex

locator was compared using single canal single rooted teeth (incisor, canine and lower

premolar teeth) that were to be extracted for periodontal or orthodontic reasons. An intraoral

periapical (IOPA) radiograph was taken. The tooth was then extracted under local anaesthesia

along with the file in the tooth. The distance of the file tip from the apex was measured under

3X magnification and the reading recorded. It was observed that the radiographic method had

a significant variation from the electronic method when compared to the actual measurement

Review of literature

16

method as compared to radiographic method for determination of working length of the root

canal.29

3.

This ex vivo study compared the accuracy of three different electronic apex locators (EALs)

in detecting the apical foramen and the accuracy of digital radiography and EALs in

determining the working length (WL) with visible control under a microscope; and the

precision of #10, #15, and #20 K-files in electronic measurements. The length of 101

extracted human teeth was measured with three different EALs (Endex , ProPex II and Root

ZX ), with radio videography (RVG) and compared with the actual length. An endodontic

training kit was used during the experimental procedures. Statistical analysis showed that

Endex and ProPex II were more accurate than Root ZX in determining the WL and no

significant difference between the three different K-file sizes measurements. EALs showed to

be more accurate in determining the WL than RVG and Instrument sizes of hand files did not

affect the accuracy of EALs.30

4.

This clinical study was done to compare the effect of working length determination using

electronic apex locator or working length radiograph on the length adequacy of final working

length as well as the final obturation. In 84 patients with 188 canals who were randomized

into two groups; in group 1, the working length was determined by working length

radiograph, whereas in group 2, it was determined by the Raypex5 electronic apex locator.

The results of endodontic treatment using the electronic apex locator are quite comparable, if

not superior, to the radiographic working length measurement regarding the rates of

acceptance of cases. In addition to reducing the radiographic exposure, electronic apex

17

5.

This study evaluated the accuracy and reliability of tooth-length and root-length

measurements derived from cone-beam computed tomography (CBCT) volumetric data.

Using the Dolphin imaging software the CBCT scans were oriented twice for each tooth

using the mesial, distal, labial, and lingual cementoenamel junctions as reference points.

Root and tooth lengths were derived from these points and compared with actual

measurements of the teeth made with digital calipers after all surrounding bone had been

carefully removed. Within-trial method errors were almost 2 times greater for the

periapical radiographs than for the CBCT scans. Between trial method errors were

greatest for the 0.4-mm CBCT scans, which were within 0.1 mm of the periapical

radiograph method errors. The intraclass correlations for the periapical and CBCT

measurements were allabove 0.995. CBCT scans are at least as accurate and reliable as

periapical radiographs32

6.

The objectives of this study were to assess the accuracy of working length determination

using 3 electronic apex locators and direct digital radiography and to compare the results with

those obtained using the visual method. The results suggested that electronic apex locators

are useful in determining the ideal working length for root canal preparation, obturation and

also in locating the cemento-dentino-canal junction. These devices become more precise,

especially in the presence of deviation of the apical foramen from the anatomic root apex, in

which the radiographic method yields poor results. In this study, Root ZX and Elements

Review of literature

18

7.

The purpose of this study was to compare the ability of radiographic and electronic methods

to determine reliably the location of the apical constriction. An ex vivo study was conducted

on 20 premolars with intact single straight root canal. After the coronal flaring and irrigation,

the radiographic working length was determined with a k- file and electronic length using

(EL-Root-ZX) 3rd generation apex locator. After extraction of all the premolars,

stereomicroscope was used to confirm and compare radiographic and electronic apex locator

working length values.34

8.

The aim of this in vivo study was to evaluate the accuracy of the Root ZX,

Elements-Diagnostic, Precision AL and Raypex 5 electronic apex locators when compared to

radiographs for locating the apical constriction. Under clinical conditions EALs identified the

AC with greater accuracy than radiographs. In addition, only 0.6% (average) of the EAL

measurements were 1.0 mm through the AC whereas with radiographs it was 31.4%. A WL

1.0 mm through the AC will, in some cases, results in instrumenting and filling beyond the

foramen. A WL 0.5 mm short of, or at the radiographic apex, would further increase the

likelihood of this happening. EALS can increase the accuracy of WL determination.35

9.

This in vitro study compared the conventional and direct digital radiography (DDR) in

working length measurement of the root canal and assessed the significance of the different

enhancement modes provided by the software to visualize the file length. Both conventional

19

radiography must be of size 15 or greater. The enhancement feature of DDR greatly

improves the visual perception, resulting in more accurate measurements. The positive and

colorize enhancement modes were found to be more closely associated with the actual file

length than the control group and other groups.36

10.

They compared the working length determination done using three methods, namely, apex

locator (Foramatron D-10, Parkell), radiovisiography (Planmeca) and conventional

radiography (Prostyle intra, Planmeca). The results revealed that all the three methods located

the apex nearly as accurately as the actual root canal length obtained by histological ground

sectioning, and among three methods apex locator being the closest to the actual root canal

length. The study concludes that all the three techniques are equally effective in determining

working length.37

11.

This prospective, controlled clinical study was to analyze endodontic working length

measurements in preexisting cone-beam computed tomography (CBCT) scans and to

compare them with clinical root canal length determination by using an electronic apex

locator (EAL). All included patients had received a CBCT scan independent of the present

study and needed root canal treatment. Clinically, the root canal length was measured with an

EAL by an endodontist. This measurement was compared with the root canal length as

measured on vestibulooral and mesiodistal CBCT sections by an examiner not involved in the

endodontic treatment. The measurements in both slices (r = 0.97). The mean discrepancy

between RRL and CRL was 0.51 mm (median, 0.36 mm), with a range from 0.02 1.83 mm

Review of literature

20

endodontic working length measurement with a precision similar to measurements done by

EAL.38

12.

The in vivo study was aimed at evaluating the accuracy of electronic apex locator, to

determine the working length of root canal, and it was compared with the radiographic

method of working length determination. After access cavity preparation, working length was

determined using radiographic method and electronic apex locator, after which the file was

fixed with a light cured composite resin. The tooth was then extracted and was then

longitudinally grounded using straight fissure diamond bur until the root canal and the tip of

the file were visible. The distance of file from the minor constriction was measured using a

stereomicroscope. The electronic working length determination of root canal was found to be

more accurate than the radiographic method.39

13.

This in vitro study compared the accuracy of working length (WL) determination using the

Raypex 6® electronic apex locator and cone-beam computed tomography (CBCT). 150

extracted human teeth were decoronated and randomly assigned to five groups (n = 30). WL

conditions (group 1) or with 2.5% NaOCl, distilled water or Ultracain® (groups 2 4). The

radiological WL (group 5) was calculated from bucco-lingual and mesio-distal CBCT

sections. CBCT measurements were an average of 0.59 mm shorter than AL. Electronic

measurements were more reliable than CBCT scans for WL determination. The Raypex 6®

was more accurate in locating the major foramen than the apical constriction under the

21

14.

The objective of this in vitro study was to compare the accuracy of radiographic method and Propex II apex locator. Thirty single canal extracted human teeth with patent apical foramen

were selected. Access cavities were prepared. Anatomic length (AL) was determined by

inserting a K-file into the root canal until the file tip was just visible at the most coronal

aspect of the apical foramen; subsequently 0.5 mm was deducted from this measured length.

II apex locator was used to determine the electronic working length (EL). The percentage

accuracy of RL and Propex II apex locator was 76.6% and 86.6%, respectively. The results

showed that Propex II was more accurate than the radiographic method in determining

working length. Apex locator can reduced the overestimation observed in radiographic

method.41

15.

To evaluate clinical studies on the accuracy of different methods used for working length

determination in endodontics. Search was conducted on Pub med central, Medline and Mesh

data base for the related topic from 1991 to 2012. Articles were selected, if they met the

following criteria: clinical trials, clinical studies, randomized controlled trials and controlled

clinical trials.There is no significant difference between conventional methods and electronic

apex locators in the accuracy of working length determination. But electronic apex locators

and digital radiographic methods were found to be beneficial from the perspective of

radiation dose reduction.Electronic apex locators are not superior to radiographs in

determining working length. Long term follow up studies evaluating post operative success

comparing electronic apex locators and radiographic methods are needed to appreciate the

Review of literature

22

16.

The aim of this in vitro study was to determine the accuracy of root canal length

measurements performed with cone beam computed tomographic (CBCT) scans using a gold

standard. Methods: A total of 162 teeth (198 root canals) in 16 dry human dentulous

mandibles were scanned using a 3DX-Accuitomo CBCT scanner (Morita 3DX; J Morita Mfg

Corp, Kyoto, Japan). The root canal length was measured with CBCT data. All teeth were

extracted atraumatically and endodontically accessed; the root canal length was measured

blindly using a #10 K-file and served as the gold standard. The mean absolute difference of

the CBCT-based root canal length from the gold standard was 0.46 mm (95% confidence

interval, 0.41 0.50 mm). Only in 9 of 198 (4.5%) roots did the difference between the

CBCT-based root canal length and the gold standard exceed 1 mm. CBCT-CBCT-based root canal length

measurements are accurate and reliable when compared with a gold standard. 43

17.

This in vitro study was done to compare the root canal length determination by electronic

apex locator and conventional radiography, and comparing it with the actual length

measurement done by direct visualization. The accuracy of EAL and radiographic methods

were 92% and 72% respectively when compared to the actual length. Hence, EAL proved to

be more accurate in determining the root canal length than the conventional radiographic

method.44

18.

This study was to compare the precision of root canal length determination on cone-beam

computed tomographic (CBCT) scans and periapical radiographs (PAs) with the actual root

canal length. The secondary aim was to examine the influence of tooth type anterior and

23

canal length measurement was performed by a consensus panel (2 examiners) on CBCT

scans and digital PAs. After access opening, a #15 file was fixated in every root canal at the

length measured on CBCT scans. All teeth were extracted, and the root canal containing the

file was uncovered. Measurements made on images taken with a digital camera linked to a

stereo-zoom microscope were used as the actual root canal length. The root canal length

measurements of posterior maxillary teeth, they were significantly more accurate than Pas

when CBCT images were used.45

19.

This in vitro study was done to evaluate the accuracy of working length determination

using cone beam computed tomography. The results showed that using a simplified method,

CBCT images of 0.2mm voxel size can be used to accurately determine the endodontic

working length.46

20.

This article reviewed the use of CBCT imaging in the diagnosis, treatment planning, and

assessing the outcome of endodontic complications. Intraoral radiography is the imaging

technique of choice for the management of endodontic disease, but CBCT appears to provide

a superior validity and reliability in the detection of periapical lesions. The superior accuracy

of CBCT imaging helps in the early detection of periapical lesions and may help to determine

their exact locations and extents. CBCT imaging can potentially become the first choice for

endodontic treatment planning and outcome assessment, especially when CBCT with lower

radiation doses and better resolutions become available. However, endodontic cases should

Review of literature

24

information from conventional imaging systems may not yield adequate amounts of

information to allow for the successful management of endodontic problems.47

21.

The aim of this clinical study was to compare the effect of working length determination

using radiovisiography (RVG) and two-dimensional (2D) and three-dimensional (3D)

measurements using cone-beam computed tomography (CBCT).Thirty mandibular teeth were

taken and three groups of 10 each were made.The root canal length was determined using

RVG, CBCT measurement method 2D, and CBCT measurement method 3D. The difference

between CBCT measurements, RVG, and the actual canal length were compared to evaluate

the accuracy of each method. No significant statistically difference was seen with 3D

measurements and actual measurements. Measurements with RVG were better than CBCT

2D. CBCT 3D measurements are accurate than RVG and CBCT 2D in the determination of

root canal length.48

22.

In this ex- vivo study of evaluating the accuracy of WL determination by using conventional radiography, digital radiography, and EALin working length (WL) determination. Ability to

measure WL was detected precisely and in acceptable range that is ± 0.5 mm of actual

WL.The mean value of differences between three experimental methods length and the actual

WL were statistically significant. EAL gave the most accurate readings out of all the

experimental groups, with 100% accuracy within the acceptable range where as digital

radiography gave the least accurate reading. The electronic method (Justy II apex locator)

25

23.

The aim of this study was to compare the accuracy of working length measured by electronic

apex locator and periapical radiograph. Thirteen teeth with 23 canals were selected. Working

lengths of all canals were measured using K file with apex locator and periapical radiographs.

Access opening was filled with restorative GIC with the files present in canals. Teeth were

then subjected to extraction. All extracted teeth were evaluated by sectioning the lower half

or lower one third of the apices longitudinally. The distance of the file tip from the minor

constriction was measured and recorded. The results of the study showed that accuracy of

apex locator were 65% (n=15) with the file tip at minor constriction, while 22% (n=5) for

periapical radiograph. Thus it was concluded that electronic apex locator is more accurate and

reliable then periapical radiograph.50

24.

The aim of this study was to compare digital and conventional radiography in determining the

working length of dilacerated canals.Thirty nine human extracted single-rooted teeth with

root curvature more than 35 degrees were included in this study. The true canal length was

determined for each canal. Then, teeth were mounted in acrylic blocks and canal length was

estimated by using on-screen digital radiography with both 3- and 6-clicks measurement and

from conventional radiography by conforming a preserved file on the image of the root canal.

There were no significant differences in measurement accuracy between the true canal length

and conventional radiographic length, but there were significant difference between both

digital radiographic techniques with true canal length. There was no significant correlation

Review of literature

26

canals, the accuracy of determination of working length by using conventional radiography is

higher than digital radiography.51

27. André Luiz Gomide de Morais 2016

The purpose of this clinical study was to compare the accuracy of working length (WL)

determination using cone-beam computed tomography (CBCT), conventional periapical

radiographies and electronic apex locator. 19 patients with a total of 30 single-rooted teeth

diagnosed with apical periodontitis were selected for this study. After taking the initial

parallel periapical radiographs, the initial file was advanced into the canal until the WL was

detected by the Root ZX apex locator and measured. WL radiographs were taken with the file

set in the canal. Afterwards, CBCT images were acquired and actual working length was

measured. The mean values for WL determination by electronic apex locator, periapical

radiograph and CBCT images were 22.25, 22.43 and 22.65, respectively which was not

statistically significant. The determination of the working length of root canal using CBCT

images was precise when compared to radiographic method and electronic apex locator.52

28. Jhadye Alves Carneiro 2016

The objective of this ex vivo study was to evaluate the accuracy of electronic apex locator for teeth were used in this study. After coronal access, manual measurement of the real working

length o

exceeding of the file in the apical foramen. The file was retracted by 1 mm, and its extension

was measured to determine the real working length. The electronic measurement of the

working length was performed in the same teeth using the Joypex 5 electronic apex locator.

27

and manual methods (P > 0.05). the electronic device for measuring the root canal length

53

29. Yakup Ustun, 2016

This study evaluates the endodontic working-length measurements in teeth with large

periapical lesions and persistent intracanal exudate by using preexisting cone-beam computed

tomography (CBCT). It compares the measurements with clinical root canal lengths

determined by using 2 electronic apex locators. Seventy-three teeth with single roots and

canals were studied. The working length of each canal was measured with 2 different

electronic apex locators- Propex pixi and Raypex 6. The measurements were repeated 3 times

by using a digital caliper, and the mean was recorded. This mean was compared with the root

canal length as measured on CBCT sections. The median values for CBCT, Raypex 6, and

Propex Pixi measurements were 21.10, 21.36, and 21.55, respectively. Statistical analysis

showed no significant difference between the Raypex 6, Propex Pixi, and CBCT evaluations.

in teeth with a large periapical lesion with intracanal exudate, CBCT images with a voxel size

of 0.125 mm show comparable results with measurements made with the Raypex 6 and

Propex Pixi devices.54

30. Swapna et al. (2017)

In this study they combined the application of correction factors and the use of IOPA grid to

obtain the radiographic working length values and have further compared them to the

working length values obtained by the apex locator (Morita ZX) to determine the success

rates of the radiographic technique in cases where apex locators cannot be used or are not

Review of literature

28

showed 1 mm as the correct correction factor to be deducted from the tooth length measured

by the IOPA grid.55

31.Mohammad Mahdi Yaghooti Khorasani 2017

The aim of this study was to compare the accuracy of conventional and digital radiographic

techniques for root canal working length determination. After determining the real working

lengths of 50 permanent maxillary central incisors (gold standard), the conventional (E- and

F-speed films) and digital (CCD, PSP) images were obtained using the parallel technique.

The mean registered working length of each modality was compared with the other and with

the gold standard. No significant difference was found between the recorded working length

values using the conventional and digi-tal radiographic techniques (P=0.828). Within the

limitations of this study, it was concluded that there was no difference between the

measurement accuracy of CCD, PSP and conventional imaging techniques in root canal

working length determination.56

32. (2017) :

The aim of this study was to evaluate the accuracy of working length determination by using

an electronic apex locator, periapical radiography, and cone-beam computed tomographic

(CBCT) imaging obtained at different voxel sizes and field of views (FOVs) in extracted

human teeth. All CBCT images obtained at different FOVs with voxel sizes less than 0.3

mm3 performed similarly and better than intraoral periapical radiography in the

determination of endodontic working length measurement. Apex locator measurements were

better than CBCT and periapical images, and they correlated highly with actual length

29

evaluated in the absence of streak and beam hardening artifacts, motion artifacts, and

anatomic noise from the opposing jaw structures.57

33. Fernanda Gracia et al. (2017)

This in-vivo study was done to assess the accuracy of 2 third-generation electronic apex

locators , Propex II (Dentsply Maillefer) and Root ZX II (J. Morita), and radiographic

technique for locating the major foramen . The measurements obtained using the visual

method exhibited the strongest correlation with Root ZX II (r = 0.94), followed by Propex II

(r = 0.90) and Ingle's technique (r = 0.81; p < 0.001). Descriptive statistics using ANOVA

(Tukey's post hoc test) revealed significant differences between the radiographic

measurements and both EALs measurements (p < 0.05). Both EALs presented similar

accuracy that was higher than that of the radiographic measurements obtained with Ingle's

technique. The results suggest that the use of these EALs for major foramen location is more

accurate than the use of radiographic measurements.58 34. Kaushik Dutta et al (2017):

In this in vitro study they compared the measurement of working length with three different

methods manual tactile sensation, digital radiography and Mutidetector computed

tomography(MDCT). ANOVA and turkeys test showed that there was no significant

difference in the measurements by the three procedures (p>0.05). Working length

measurement with MDCT scan and other two conventional methods does not show

significant difference in measurement. Use of newer 3D imaging technique is useful in root

Review of literature

30

35.Mohamed I. Elshinawy et al (2017):

This in vitro study compared four different working length determination techniques. The

working lengths were repetitively determined in five groups (n = 50 each) using regular tomographic image (group 3), electronic apex locator (group 4) and direct measurement

(group 5, control) by subtracting 0.5 mm from the length of

foramen. The collected data was statistically analyzed using both analysis of variance and

least significant difference (LSD) comparisons at P value less than or equal to 0.05. The difference between the data of study groups (P = 0.011). The LSD comparisons revealed a longer working length (LSD, P

and 2 than groups 3 and 5 (control). On the other hand, no difference (LSD, P > 0.05) was detected between the working length in groups 3 and 4 in comparison with group 5 (control).

radiographs.60

36. Divya Saxena et al, (2017):

This ex vivo study was to comparatively evaluate the accuracy of iRoot, iPex II, and Propex

pixi apex locator using histological sections as the gold standard. Working lengths (WLs) of

teeth were determined using iRoot, iPex II, and Propex pixi. Teeth were then extracted, and

anatomic canal length (ACL) were measured. The apical 4 mm of the roots were

longitudinally shaved away to visualize the canal under a stereomicroscope at ×24

magnification. Digital photographs were evaluated to measure the distance between the major

diameter and minor diameter. Thus, the WL, that is, the minor diameter length (MDL) was

31

acceptable for iRoot, 86.66% for iPex II, and 80% for Propex pixi when compared with mean

MDL as obtained from the histological sections. All apex locators have been shown to

produce acceptable level of accuracy which clearly indicates their reliability in determining

the WL.61

37. Vidhya Bhatt 2017:

The purpose of this study was to evaluate the accuracy of a new-generation electronic apex

locator (iPex) to determine working length in primary teeth with or without root resorption as

compared with the conventional radiographic method. A sample of 30 primary posterior

teeth which are indicated for pulpectomy were selected for the study. Initially, working

length was obtained with iPex (new-generation by Nakanishi International) apex locator

using no.10 K-file, which was then compared with convent

method). In the present study, accuracy of iPex was 70.8% within ±0.5 mm and 90.8% within

±1 mm.There was no statistically significant difference found when using iPex apex locator

for working length determination as compared with that of conventional radiographic

method. Hence Working length determined by iPex apex locator is comparable with that of

conventional radiographic method, hence, can be used as an alternative in determining the

working length of primary teeth.62

38. Cihan Yildrim 2017

The goal of the cone beam computed tomography (CBCT) based investigation was to

compare determination of the WL performance of the electronic apex locator (EAL), CBCT

and digital radiography. 30 single rooted, freshly extracted permanent teeth were included.

Root canal WL measurements were performed using actual length (AL), EAL, digital

Review of literature

32

most accurate method to evaluate the root canal WL, with accuracy of 70%. Accuracy for the

apex locator and periapical radiograph were 40% and 30%, respectively. The CBCT may be

safe to use in determining root canal WL. Because lower radiation dose, a pre-existing CBCT

can be useful to detect the root canal WL more precisely.63

39. Tanikonda Rambabu et al (2018):

The aim of this in-vivo study is to compare and evaluate the preoperative estimated WL with

conventional radiograph and with grid radiograph, with reference to electronic apex locator

The statistical package for the social sciences (SPSS) version

16.0 (SPSS Inc., Chicago, IL, USA) was used to compare the WLs of three groups, and the

statistical significance was considered to be P post hoc test were made to measure the intergroup comparison, and Pearson correlation values were obtained. The

results of the study showed a higher correlation between grid WL and apex locator WL than

conventional WL and apex locator WL. Preoperative metrics with radiographic grid along

with the apex locator is a better measuring tool compared to the conventional radiographic

64

40. Syed Shahbaz 2018

The objective of this study was to compare the working length determination done using

three methods, namely, radiovisiography and conventional radiography, apex locator (Root

ZX mini, MORITA). In this research, to determine the working length, 40 single-rooted teeth

(mandibular first premolars) were selected and each tooth was subjected to all the three

methods of the working length determination. This was compared with the actual working

length measured utilizing ground sections of the individual teeth. The results revealed that all

33

obtained by histological ground sectioning, and among three methods apex locator being the

closest to the actual root canal length.65

41.Razavi 2018

This study aimed at assessing accuracy of digital radiography with different enlargements in

determining working length of root canal and comparing it with standard method. 30

extracted single rooted premolar teeth root canal was prepared. One file with 15 mm size

was placed into canal to the point that its end was observable in canal apex. Firstly, canal

length from reference point was measured based on millimeter and it was measured based on

shortening the length for 0.5 millimeter and it was calculated by 0.1 mm accuracy. The

Radiographic images of indirect digital periapical was provided for all samples by parallel

method after preparing radiography by Scanora software, images were changed into

conventional radiography film size and then they were saved by 2 and 3 times enlargements.

Accuracy of 1x, 2x and 3x enlargements of indirect digital radiography were 95.1%, 96.3%

and 95.9% respectively. Accuracy of enlargements of indirect digital radiography for

estimating root working length were very similar either in general status or in each observers

and there was no significant difference in different enlargements.66

42. Jorge Paredes Vieyra 2018

The aim of this study was to evaluate in vivo the accuracy and predictability of two EALs for determining working length as compared to radiographs: RootZX and CanalPro. One hundred

and sixty teeth (493 canals) with fully formed apices (confirmed by radiographic evaluation

before treatment) and apical periodontitis were used. The Apical Constriction (AC) of each

tooth was located with two electronic apex locators. The measurements obtained by the two

Review of literature

34

For premolar teeth, the Root ZX, CanalPro and radiographs located the minor foramen 79%,

64% and 28% of the time, respectively. Under clinical conditions, the EALs identified the

minor foramen with high degree of accuracy. EAL were more accurate, compared to

radiographs with the potential to greatly reduce the risk of instrumenting and filling beyond

the apical foramen.67

43.Andre Kaled Segato et al 2018:

This study investigates the accuracy of 3D Endo software to determine the working length

when using preoperative cone-beam computed tomographic (CBCT) scans of extracted

teeth, compared with conventional CBCT software and an electronic apex locator (EAL).

CBCT scans of 30 premolars were obtained., the measurement obtained from the coronal

reference to the apical foramen (AF) was recorded as the conventional CBCT length. Then,

using 3D Endo software suggested length SL) and the operator-adjusted length

(3D-OL) were obtained. Teeth were accessed, and the actual length was measured. Finally, the

teeth were measured using the electronic apex locator (EL) using the EAL Root ZX. The

preoperative working length determination using 3D Endo was reliable and similar to

conventional CBCT software. However, the combined use of CBCT with an EAL is

Aim and Objectives

35

AIM

The aim of this study was to determine the accuracy in measuring the working length of root

canal using Tactile Method, Digital Radiographic Method and Electronic Apex Locator, in

Mandibular Premolars in-vivo, comparing the lengths so measured to the actual working

length measured after extraction using CBCT and Magnifying loupeex-vivo.

OBJECTIVES:

1. To compare the accuracy of 3 methods of working length determination in

mandibular Premolars in-vivo : Tactile method, Digital Radiographic Method and

Electronic Apex Locator.

2. To determine the accuracy of the working length measured after extraction ,using

CBCT ex-vivo.

3. To evaluate the level of reliability of four groups TWL, RWL, EWL and CBCTWL

Materials and Methods

36

SAMPLE SELECTION:

Sixty human single-rooted, mandibular premolar teeth with mature apices, scheduled for

orthodontic extraction FIG-6 were selected for the study. Informed written consent was

obtained from each patient before treatment.

(

FIG 6 PRE-OPERATIVE OPG

FIG 7 (A): CONSENT FORM English FIG 7 (B): CONSENT FORM - Tamil

Inclusion criteria

1. Single rooted tooth

2. Presence of single canal

3. Non-carious teeth

37

Exclusion criteria

1. Carious teeth

2. Periodontally compromised teeth

3. Morphologically defective teeth

4. Open apex

5. Young patients with cardiac pacemaker

MATERIALS AND INSTRUMENTS USED:

TABLE 5: ARMAMENTRIUM

S.No Materials used Brand name/ manufacturer details

1. Lignocaine 2% 1:80000 Adrenaline Lignox

2. 2.5 % Sodium hypochlorite solution Prime dental, India

3. EDTA gel Endo Prep gel , Globus medicus , India

4. Normal saline NS, Orchid pharma , India

Materials and Methods

38

S.no Instruments / Equipments used Brand name/ Manufacturer details

1. Rubber dam kit GDC dental, India

2. Diagnostic instruments GDC dental, India

3. Endo access bur EX 41 MANI Dia-Burs EX-41

4. High speed airotor handpiece NSK pana max plus, Japan

5. K files # 10 40 MANI , Tochigi, Japan

6. Endogauge DiaDent , Korea

7. 2ml and 5ml disposable syringe DispoVan, India

8. Propex II apex locator Dentsply Maillefer, Ballaigues, Switzerland

9. SOPIX- RVG unit Satelec ,Acteon Sopix 2 Dental Oral Sensor

10. Magnifying loupe Carl Zeiss Meditec, Germany

11. CBCT unit NEWTOM cone beam CT

Radiology, Verona, Italy

39

METHODOLOGY:

A good quality preoperative radiograph was taken employing the extension cone paralleling