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ORIGINAL ARTICLE
Year : 2015  |  Volume : 3  |  Issue : 1  |  Page : 28-33

Comparison of accuracy of Root ZX II and Root ZX Mini in presence of various irrigants: an in vitro study


1 PG Student, Department of Conservative Dentistry and Endodontics, K.M.Shah Dental College & Hospital, Piparia, Waghodia, Vadodara- 391760, India
2 Professor, Department of Conservative Dentistry and Endodontics, K.M.Shah Dental College & Hospital, Piparia, Waghodia, Vadodara- 391760, India
3 PG Student, Department of Prosthodontics, Darshan Dental College, Loyara, Udaipur -313001, India

Date of Web Publication3-Aug-2018

Correspondence Address:
D S Vaid
PG Student, Department of Conservative Dentistry and Endodontics, K.M.Shah Dental College & Hospital, Piparia, Waghodia, Vadodara- 391760
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/2347-6486.238516

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  Abstract 


Aim: Comparison of the effect of QMix, 7% maleic acid and 2.5% sodium hypochlorite on the accuracy of Root ZX II and Root ZX Mini apex locator.
Methodology: 45 single rooted teeth were decoronated. Patency was checked and coronal flaring was done. They were then divided into 3 groups: i) QMix, ii) 7% Maleic acid and iii) 2.5% Sodium hypochlorite. The actual length of each tooth was determined before embedding them in an alginate model. 5ml of the respective irrigant was introduced into the canal. Working length was measured with Root ZX and Root ZX Mini apex locators. For each sample, an average of a total of three readings was considered. Statistical analysis was performed using Anova, Two Way, Post hoc, Paired t-tests.
Results: Group I (QMix) showed no statistically significant results. Group II (7% Maleic acid), showed statistically significant difference from the actual length with Root ZX Mini (p=0.002). Group III (2.5% sodium hypochlorite) showed statistically significant difference from the actual length with Root ZX II (p=0.04) and Root ZX Mini (p=0.0002). A statistically significant difference was seen in the readings by both the apex locators (p=0.005).
Conclusion: QMix does not affect the accuracy of apex locators. Root ZX II is more accurate than Root ZX Mini in the presence of 7% maleic acid and 2.5% sodium hypochlorite.

Keywords: working length, electronic apex locator, root canal irrigants, QMix, maleic acid


How to cite this article:
Vaid D S, Shan N C, Kothari D M, Bilgi P S. Comparison of accuracy of Root ZX II and Root ZX Mini in presence of various irrigants: an in vitro study. J Integr Health Sci 2015;3:28-33

How to cite this URL:
Vaid D S, Shan N C, Kothari D M, Bilgi P S. Comparison of accuracy of Root ZX II and Root ZX Mini in presence of various irrigants: an in vitro study. J Integr Health Sci [serial online] 2015 [cited 2019 Jun 19];3:28-33. Available from: http://www.jihs.in/text.asp?2015/3/1/28/238516




  Introduction Top


Accurate determination of root canal length is of prime importance for successful root canal treatment.[1]Working length is defined in the endodontic glossary as ‘the distance from a coronal reference point to the point at which canal preparation and obturation should terminate.’[2]

The cementodentinal junction (CDJ) is the anatomical and histological landmark which determines the end of pulp and start of periodontal ligament. Hence, biomechanical preparation and obturation of the root canal should be done till this point.[3]

Traditionally, radiographic method has been used to determine the working length, but it has got several disadvantages like variations in technique, distortion of image, and may lead to errors. Hence, electronic determination of working length has become important.

Electronic apex locators (EALs) are widely used during root canal treatment to determine the working length. Their principle for working is that the electrical conductivity of the tissues surrounding the apex of the root is greater than the conductivity inside the root canal system provided the canal is either dry or filled with a nonconductive fluid.[4]

Root ZX (J. Morita Corp., Kyoto, Japan) is a third- generation apex locator which uses the impedance ratio of two frequencies (8 and 400 Hz) to measure the working length.[5] It is the most popular and frequently tested third generation EAL.BR Duh in his study showed Root ZX had an accuracy of 90.48% to 97.62%( ± 0.5 mm) of the apical foramen.[6] A new EAL of the Root ZX series, Root ZX II (J. Morita Corp., Kyoto, Japan) is marketed with a canal measurement module as well as a low speed handpiece module. It helps in the preparation of the root canal as well as determination of the working length simultaneously.[7]

Root ZX Mini (J. Morita Corp., Kyoto, Japan) is a smaller and compact version of Root ZX II. Mohammad Yosefi in his study has shown acceptable results in working length determination when compared to conventional radiography.[8] The manufacturers claim that it has the same accuracy of the Root ZX II.[6] Al-Hadlaq (2012) found no statistically significant difference in the accuracy of Root ZX and Root ZX Mini in the presence of different concentrations of sodium hypochlorite. But their accuracy in the presence of other irrigants has not been compared. Hence, one of the aims of this study was to compare the accuracy of Root ZX II and Root ZX Mini apex locators.

For the disinfection of root canal, various irrigating solutions in various concentrations, pH and compositions are being used; and the electroconductivity of these solutions is said to affect the results of the electronicworking length measurements. Some authors have suggested not using highly conductive solutions for working length measurement. The true effect of various solutions is still controversial.[4]

Sodium hypochlorite is the most commonly used irrigant for disinfection of root canals. A study by Jenkins et al. (2001) showed that sodium hypochlorite showed the greatest deviation from the actual length with Root ZX.

QMix 2in1 (DENTSPLY, Tulsa, USA) is a new irrigating solution for use as a final rinse before obturation in root canal treatment procedures. It is a premixed solution of a chelating agent (EDTA), an antimicrobial (chlorhexidine) and a surfactant. Limited literature is available on its effect on electronic length measurement.

Maleic acid is a mild organic acid that efficiently removes smear layer and offers several advantages over the conventionally used EDTA as chelating agent. As it is also a new irrigant and hence no research has been done to test its efficacy on electronic length measurement.

Thus, the purpose of the present study is to test and compare in an in vitro model, the effect of various irrigating solutions on the accuracy and reliability of Root ZX II and Root ZX Mini. The null hypothesis is that the presence of irrigants in the root canal has no effect on the accuracy of both the electronic apex locators.


  Methodology Top


45 human permanent, intact premolars and maxillary anteriors with single canals and mature apices were selected by direct clinical examination for this study. Type I configuration of root canal was confirmed with digital radiography in mesiodistal and labiolingual planes. Before the test, the teeth were stored in 5% formalin solution (Balaji Formalin, Pvt Ltd, Gandhinagar, India) for seven days for disinfection and placed in 0.5% sodium hypochlorite solution (Prime Dental Products, Thane, India) for 2 hours to remove the organic tissues. All remaining organic residues were removed from external root surfaces with an ultrasonic scaler (Satelec Acteon Group, MérignacCedex, France). After rinsing with tap water, teeth were transferred to 0.9% saline solution (Nirlife Healthcare, Nirma Ltd, India). All the teeth were treated by the same operator.

The teeth were decoronated at the level of cementoenamel junction which allowed access to the root canal and provided a stable reference point for all measurements. Canal patency was evaluated using a 10 or 15 K-file (Mani Inc., Utsunomiya, Japan) and any teeth with canal obstructions were discarded. Pulp tissue if present was removed with a barbed broach (Mani Inc., Utsunomiya, Japan).

Subsequently coronal flaring was done with sequential Gates Glidden drills #4, #3 and #2 (Mani Inc., Utsunomiya, Japan).and irrigated with saline. The teeth were randomly divided into 3 groups consisting of 15 teeth each and numbered from 1-45.

Randomization was done by computer method.

The solutions in to which the groups were assigned are as follows:

  1. QMix (Dentsply, Tulsa, USA) (n=15)
  2. 7% Maleic acid (Sd Fine-Chem Ltd., Mumbai, India) (n=15)
  3. 2.5% Sodium hypochlorite (Prime dental Products Pvt.Ltd., Thane, India) (n=15)


The actual length of each tooth was determined by introducing a # 10 or # 15 K file into the canal until its tip emerged through the major apical foramen. After carefully adjusting the silicon stopper, the file was withdrawn from the canal and the distance between the file tip and the stopper was measured to the nearest 0.5 mm; 0.5 mm was subtracted from this length and recorded as actual length. All the specimens were stored in distilled water until working length determination using apex locators.

An alginate model was prepared by mixing alginate powder (Prime dental Products Pvt.Ltd. Thane, India.) with water as per the manufacturer’s instructions and it was used within 2 hours of mixing of alginate. Alginate is a good medium to establish the necessary electric circuit for a correct electronic apex locator measurement, because it mimics well the electric impedance of the human periodontium. The tip of metal clip of the apex locator was placed into the alginate model and stabilized. The tips of all samples of group 1 were embedded in the model. Similarly, models were prepared for group 2 and group 3. For each tooth, the canal was dried with paper points. For group 1, the teeth were irrigated with QMix. For group 2, the irrigating solution used was 7% Maleic acid and 2.5% sodium hypochlorite was used as irrigating solution for group 3. Canals were irrigated with 5ml irrigating syringe and 24 gauge needle (Hisdustan syringes and medical devices, Faridabad, India).

The apex locator was turned on and file holder was attached to #10 or #15 K file. The length was measured according to the manufacturer’s instruction. For each group, the measurements were taken three times per tooth. An average of a total of three readings was considered. The root canal lengths in all the groups were recorded in the same way with Root ZX and Root ZX Mini apex locators. All the measurements were carried out by a single operator.

Statistical analysis was performed using Anova, Two Way, Post hoc, Paired t-tests. (p=0.05)


  Results Top


The electronic working lengths obtained with Root ZX II and Root ZX Mini apex locators in the presence of QMix, 7% Maleic acid and 2.5% Sodium hypochlorite were compared with the actual lengths.The mean, standard deviation and p-value are given in [Table 1].
Table 1: Comparison between the actual length and the working lengths obtained with Root ZX II and Root ZX Mini apex locators in the presence of QMix, 7% Maleic acid and 2.5% Sodium hypochlorite

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The results showed that for group I (QMix), there was no statistically significant difference in the mean value from the actual length with both Root ZX II (p= 0.234) and Root ZX Mini (p=0.20) apex locators. Also, no statistically significant difference was found when the mean values from both the apex locators was compared (p=0.63). In Group II (7% Maleic acid), statistically significant difference from the actual length was seen with Root ZX Mini (p=0.002), while no significant difference was found with the Root ZX II apex locator (p=0.12). There was so statistically significant difference in the mean values of the two apex locators (p=0.173). In Group III (2.5% sodium hypochlorite), statistically significant difference from the actual length was seen with Root ZX II (p=0.04) and Root ZX Mini (p=0.0002). A statistically significant difference was seen in the readings by both the apex locators (p=0.005).


  Discussion Top


In the present context, there is a concern that root canal irrigants, available in different concentrations, pH and compositions can affect the readings of EALs and give inaccurate working length. But the true effect of various solutions is still controversial.[4]

The manufacturers of Root ZX II and Root ZX Mini claim that them to be accurate in the presence of irrigants.[11],[12] Hence, the purpose of this study was to compare the accuracy of both Root ZX II and Root ZX Mini in the presence of various irrigating solutions.

Ibarrola et al. (1999) and de Camargo et al. (2009) found preflaring of canals to increase the efficacy of the Root ZX apex locator. Hence, preflaring of coronal portion of all the teeth was done using sequential Gates Glidden drills #4, #3 and #2.[13],[14]

Also, to take measurements with EALs, it was necessary to simulate the periodontium. For this, a number of experimental models have been proposed and the materials most often used are alginate, agar, saline, and gelatin. Alginate is considered to be good medium to establish an electric circuit for measurements with electronic apex locator, as it mimics the electric impedance of the human periodontium. Hence, alginate model was used in this study. It proved to be easy to make and cost effective.[4]

Alginate loses moisture with time, which invariably affects the results of the experiment. Many studies identified a 2-h timeline for using the freshly mixed alginate. Hence, in this study the measurements were recorded within 2 hours of mixing of alginate.[15]

Sodium hypochlorite is the most widely used root canal irrigant and is considered to be the gold standard. Goel et al.(2006) and Jain et al. (2012) found a highly significant statistical difference between the actual canal length and Root ZX measurements in presence of 2.5% of NaOCl.[16],[17] On the contrary, Meares WA et al showed Root ZX not to be adversely affected by the presence of sodium hypochlorite.[18]

Jenkins et al. (2001) found Root ZX electronic apex locator to reliably measure canal lengths regardless of the irrigant. However, the largest deviation from the actual length was obtained with NaOCl.[9]

In the present study also, highest deviations from the actual length were found in Group III (sodium hypochlorite) with both the apex locators. This can be attributed to the high electroconductivity of the irrigant (Electroconductivity 66mS, pH 11.72).[19]

With conductive solutions inside the canal, minimal changes are seen in electrical characteristics once the file approaches the foramen. This complicates electrical determination of the foramen. Meredith and Gulabiwala reported an increase in resistance with increasing distance from the apex for dry canals (22.19–92.07 kΩ) and these figures were significantly higher than for those containing sodium hypochlorite (7.46–8.92 kΩ). Thus, changes in resistance were measured easily in dry root canals. Kim et al found the file to go deeper in a higher electroconductive condition such as NaOCl, whereas it would go less deep in a lower electroconductive condition.[4]

Before obturation, a final rinse with an irrigating solution is recommended to remove the smear layer and disinfect the canals. Also, working length should be reconfirmed. Hence, it is important to determine the effect of these solutions on electronic working length determination.

QMix 2in1 (DENTSPLY, Tulsa) is a new irrigating solution for use as a final rinse after NaOCl in root canal treatment procedures. It is a premixed solution of a chelating agent (EDTA), an antimicrobial (chlorhexidine) and a surfactant.[19],[20] Colin Eliot showed that QMix formulations were superior to EDTA in smear layer removal and exposure of dentinal tubules in the root canal system[21]. The individual effects of its components, chlorhexidine and EDTA, on EALs has been previously studied; but the combined effect as seen in QMix is still unknown.

Goel et al.(2006) and Jain et al. (2012) in their studies found chlorhexidine to give the most precise measurements with EALs as compared to NaOCl.[16],[17] Jenkins et al and Al-Hadlaq SM found that the accuracy of Root ZX was not influenced by 1.2% CHX or 17% EDTA.[9],[10] Joshi et al. concluded that 2% Chlorhexidine is the most reliable irrigating solution for working length determination by electronic apex locator, followed by 17% EDTA.[4]

In the present study also, the most accurate results were obtained with Group I (QMix) with both the apex locators. This can be attributed to the low electroconductivity of the individual solutions, chlorhexidine (electroconductivity 1mS and pH 6.5) and EDTA (electroconductivity 40mS and pH 7.01).[19]

-Maleic acid is a mild organic acid used as an acid conditioner in adhesive dentistry. It efficiently removes the smear layer at 5% and 7% concentration. Maleic acid, a new irrigant proposed as an alternative to EDTA, gave better results in smear layer removal and biocompatibility. Its electroconductivity has not yet been determined.[20],[22],[23]

The results of the present study showed no significant difference from the actual length with Root ZX in the presence of 7% maleic acid; however, there was a statistically significant difference with Root ZX Mini apex locator.

The accuracy of two EALS, Root ZX II and Root ZX Mini, was also compared in the presence of various irrigants. The statistical analysis demonstrated that the accuracy of measurements with both EALs was affected by the presence of 2.5% sodium hypochlorite. Also, in the presence of 7% maleic acid, Root ZX II gave more consistent readings than Root ZX Mini, thus proving Root ZX II to be more accurate than Root ZX Mini apex locator.

One major drawback with the present study was blinding. As the operator was needed to be aware of the handling techniques of the irrigating solutions as well as the apex locators, complete blinding could not be done. Also, as this is an in vitro study and does not completely replicate the clinical conditions, its clinical significance decreases.

Thus, from the present in vitro study, it can be concluded that QMix is the most reliable solution for electronic working length measurement followed by 7% maleic acid, while 2.5% sodium hypochlorite is the least reliable solution. Also, Root ZX II is more accurate than Root ZX Mini apex locator in the presence of 7% maleic acid and 2.5% sodium hypochlorite.



 
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