Journal of Interdisciplinary Dentistry

: 2012  |  Volume : 2  |  Issue : 1  |  Page : 20--24

Assessment of apical deviation of root canals after debridement with the Hybrid, ProTaper and PathFile systems

Daniely A Meireles1, André A. F. Marques1, Lucas F. R. Garcia2, Angela D. B. Garrido1, Emilio C Sponchiado1,  
1 Department of Endodontics, School of Dentistry, Federal University of Amazonas, Manaus, AM, Brazil
2 Department of Dental Materials and Prosthodontics, Ribeirão Preto School of Dentistry, University of São Paulo, Ribeirao Preto, SP, Brazil

Correspondence Address:
Lucas F. R. Garcia
Department of Dental Materials and Prosthodontics, Ribeirão Preto School of Dentistry, University of São Paulo, Ribeirao Preto, SP


Aim: To assess the occurrence of apical transportation of mesio-vestibular canals of mandibular molars using two rotary techniques and one hybrid technique during shaping and cleaning. Materials and Methods: Forty-five human mandibular molars with a degree of mesial canal/root curvature of 20° to 55° were selected, which were included in acrylic resin blocks and randomly separated into three groups. Group 1-Fifteen teeth were debrided using the ProTaper rotary technique; Group 2-Fifteen teeth were debrided using the Manual Hybrid and ProTaper rotary technique; Group 3-Fifteen teeth were debrided using the PathFile-ProTaper technique. Apical deviation was assessed by the radiographic platform method that enables obtaining superimposed images of the first and last instrument used in root canal preparation in the same radiograph. Apical transportation was measured in millimeters with the aid of the Adobe Photoshop CS4 software. Results: The mean deviation for Group 1 was 0.03 mm, for Group 2, 0.1 mm and for Group 3, 0.08 mm. Statistical analysis (Kruskal-Wallis test) of the results demonstrated that there was no statistically significant difference among the samples (P>0.05) with regard to the apical deviation. Conclusion: The techniques provided minimum apical deviation.

How to cite this article:
Meireles DA, Marques AA, Garcia LF, Garrido AD, Sponchiado EC. Assessment of apical deviation of root canals after debridement with the Hybrid, ProTaper and PathFile systems.J Interdiscip Dentistry 2012;2:20-24

How to cite this URL:
Meireles DA, Marques AA, Garcia LF, Garrido AD, Sponchiado EC. Assessment of apical deviation of root canals after debridement with the Hybrid, ProTaper and PathFile systems. J Interdiscip Dentistry [serial online] 2012 [cited 2020 Aug 11 ];2:20-24
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Endodontic therapy is based on the access to the pulp chamber, cleaning and disinfection of the root canal systems for later obturation. During shaping and cleaning, maintenance of the original shape and position of the apical foramen are essential factors to obtain successful endodontic treatment. Nevertheless, several techniques have been developed to minimize errors during root canal instrumentation. However, there are still difficulties in preparing flat and curved canals effectively due to the anatomical complexity, which is a risk factor for accidents and treatment failures. [1],[2],[3]

The endodontic instrument must enlarge the root canal without causing undesirable and accentuated wear, which may favor the development of iatrogenic injuries such as a deviation from the original canal path, formation of steps and root perforations. [4],[5] Transport or deviation is a modification of the original root canal path in its apical portion. [1],[2],[3] Iatrogenic injury is considered a common occurrence particularly due to progressive wear of the concave wall of the root canal with an accentuated curvature degree. [1],[6]

In this context, new instruments are idealized, several techniques are modified and others are developed to shape and clean the root canal. Therefore, it is imperative to analyze the performance of these systems that are released on the market to prove the accuracy with regard to the morphological alterations that may occur in the apical third submitted to endodontic treatment. Thus, the aim of this study was to assess the occurrence of apical transportation of mesio-vestibular canals of mandibular molars using two rotary techniques and one hybrid technique during shaping and cleaning.

 Materials and Methods

Forty-five human mandibular molar teeth from the Tooth Bank of the School of Dentistry of the Federal University of Amazonas were used in accordance with the ethical guidelines of the Helsinki Declaration. The disinfection process was performed by placing the teeth in 0.5% chloramine solution at 4°C for 48 h followed by washing them in running water for 24 h to eliminate traces of chloramine solution. The teeth selected for the study should present complete formation of the root apex and curvature degree between 20° and 55°, classified by Schneider [7] as moderate to severe, respectively.

Coronal opening was performed with a spherical diamond bur N° 1016 (KG Sorensen, Barueri, SP, Brazil) coupled to a high-speed handpiece (Kavo, Joinvile, SC, Brazil) and compensatory wear of the mesial wall with Endo Z bur (Dentsply/Maillefer, Ballaigues, Switzerland). To standardize the sample, all the teeth were 20 mm in length as measured by a pachymeter. The teeth that were longer than 20 mm were worn in the coronal portion with the aid of the Maxcut bur (Dentsply/Maillefer, Ballaigues, Switzerland) to obtain the required length, but the specimens that measured less than 20 mm were discarded from the research.

To determine the working length, a K type file # 10 (Dentsply/Maillefer, Ballaigues, Switzerland) was inserted into the mesio-vestibular canal until it was visible in the apical foramen. The working length was calculated half a millimeter less than the length obtained with this file. Afterwards, the teeth were included in blocks of chemically activated acrylic resin and a plastic ice tray. They were stabilized by the anatomic neck by a bar of wax to prevent the resin from penetrating into the apical foramen. The apexes of the specimens were sealed with wax. After 48 h, the specimens were removed from the ice tray, identified by random numbering from 1 to 45 and separated into three groups.

Fabrication of the radiographic platform

With the purpose of obtaining standardized initial and final radiographs and assessing the presence of apical deviation, a radiographic platform was fabricated in accordance with the principles of Sidney et al. [8] It was prepared with the aid of a radiographic positioner for posterior teeth (Indusbello, Londrina, PR, Brazil) and one unit of the ice tray was used to make the resin block. A piping connection (Tigre 5 mm DN 50, Osasco, SP, Brazil) was also used, which was adjusted to the cylinder of the X-ray appliance, enabling standardization in the same position. Thus, the blocks fit the platform perfectly, allowing the radiographs to be taken always in the same position [Figure 1].{Figure 1}

Instrumentation of the root canal

Initially, a preoperative radiograph was performed with a K file # 15 (Dentsply/Maillefer, Ballaigues, Switzerland) (Groups 1 and 2) and file PathFile # 13 (Dentsply/Maillefer, Ballaigues, Switzerland) (Group 3), in the real working length previously established in the mesio-vestibular canal. All the specimens were radiographed using D-speed Kodak Insight periapical films (Eastman Kodak Company, New York, NY, USA) and the radiographic exposure time was 0.5 sec in the ortho-radial incidence. After the preoperative radiograph, the specimens were debrided by a single operator, as follows:

Group 1-Fifteen 15 teeth were debrided by the ProTaper Rotary System (Dentsply/Maillefer, Ballaigues, Switzerland) up to instrument F2. First catheterization was performed with K type files # 15 and # 20 in the temporary working length (TWL) and the mesio-vestibular canals were instrumented at rotational speed of 350 rpm using an electric motor (Adiel, Ribeirão Preto, SP, Brazil) with the SX file in the cervical third; files S1, S2, F1 and F2 were used in the working length.

Group 2-Fifteen teeth were debrided with rotary and hybrid manual technique. First catheterization was performed with K type files # 15 and # 20 in the TWL and the root canals were debrided with K type files # 15, # 20 and # 25 in WL, and the Gates-Glidden burs n° 2 (Dentsply/Maillefer, Ballaigues, Switzerland) were used in the cervical and middle third and n° 3 in the cervical third. To finish instrumentation, the canals were debrided with the ProTaper Rotary System at rotational speed of 350 rpm using an electric motor with files F1 and F2 in the working length.

Group 3-Fifteen teeth were debrided with the rotary technique with PathFile and ProTaper files. First catheterization was performed with K type files # 10 and # 20 in the TWL, followed by PathFile files #13, #16 e #19 in the WL, and the canals were debrided at rotational speed of 350 rpm using an electric motor with the SX file in the cervical third; files S1, S2, F1 and F2 were used in the working length.

The irrigation system used was Ultra Dent (Salt Lake City, UT, USA) with NAVI TIP autoclave tips, with a diameter of 30 gauges, measuring 25 mm in length, but the determined standard length was 17 mm for the tip using a silicone stop (Ângelus, Londrina, PR, Brazil), and the solution used was 2.5% sodium hypochlorite.

After shaping and cleaning, the test specimens were submitted to a new radiographic exam with the memory instrument placed in the real working length. Therefore, superimposed images were obtained of the first and last instrument used; and the presence of apical deviation was analyzed after instrumentation. Periapical radiographs were digitalized with the aid of a digital camera (Nikon D60, Nikon, Tokyo, Japan) and imported into the Adobe Photoshop CS4 software (Adobe System Inc., San Jose, CA, USA) in order to analyze the deviation of the original root canal path in the apical third. When both instruments were superimposed in a manner that their extremities could not be differentiated, apical deviation would have not occurred. On the other hand, when the alteration occurred in the original position of the root canal, superimposition would have not occurred, leading to the visualization of the tip of the two distinct files. The distance between these files were measured in millimeters and showed the deviation of the original mesio-vestibular canal path in the apical third [Figure 2] and [Figure 3].{Figure 2}{Figure 3}


The data referring to the apical deviation in millimeters is organized in [Table 1] for better understanding. The Kruskal-Wallis test showed no statistically significant differences among the samples (P >0.05).{Table 1}


Apical deviation during cleaning and shaping of a curved root canal basically occurs due to the use of the filing movement and rigid endodontic instruments. In the filing movement, wear is directed to the external canal wall, irrespective of the instrument being curved or not. [1],[2],[3] The greater the amplitude and frequency of the movement, as well as the diameter and rigidity of the instrument, the greater displacement of the external root canal wall will be regarding to its original position, which makes adequate cleaning difficult in some areas because the instruments cannot reach them, favoring the presence of remaining necrotic tissue, leading to the failure of endodontic treatment. [4]

Apical deviation can be evaluated by several methods and the most commonly used are radiographic methods, silicone impressions of the root canals, analysis of the histological section, scanning electron microscopy and computed tomography. [2],[8],[9],[10],[11],[12],[13] For this research, the radiographic platform method developed by Sydney et al., [8] was chosen. This platform adapts to the cylinder of the X-ray appliance and enables the standardization of radiographs in the same position, as well as allowing to take two radiographs in a single film, resulting in superimposition of images from the initial and final position of the instruments, thus revealing the presence or absence of apical deviation. [9],[10],[11]

For a long time, shaping and cleaning were performed only with stainless steel manual files but, with the purpose of fulfilling the lack of flexibility of these instruments, the nickel-titanium (Ni-Ti) instruments were incorporated into Endodontics due to their super-elasticity in order to promote a lower incidence of root canal deviation during shaping and cleaning, optimizing disinfection. Several Ni-Ti systems are released in the dental market for root canal instrumentation and the remarkable characteristics are their fixed tapered files larger than the manual files. The last generation of Ni-Ti instrument commercialized in Brazil is called Universal ProTaper, now added to the PathFile system. [5]

When comparing the technique of the ProTaper system and the hybrid technique in this study, no statistically significant differences were observed because the former presented a mean apical deviation of 0.03 mm and the latter 0.10 mm, demonstrating that both groups presented low values of apical deviation, when compared with similar studies (α>0.05). Aguiar and Câmara [11] compared the techniques with the ProTaper Manual, ProTaper and RaCe systems and they also found a statistically significant difference between the proportions of deviations associated with the three instruments. The research conducted by Santos et al., [12] compared the K3 and ProTaper systems. A mean deviation in the K3 Group of 0.24 mm and in the ProTaper Group of 0.15 mm was observed, also with no statistically significant differences. In a research conducted by Setzer et al., [6] the deviation in the ProFile group was 0.12 mm, in the EndoSequence group 0.27 mm, the ProFile group followed by LightSpeed deviated 0.07 mm and ProTaper followed by LightSpeed deviated 0.16 mm, showing that there was no significant difference in apical transportation between the groups at any level of the working length.

However, in studies of Javaheri and Javaheri [10] who compared the Hero 642, ProTaper and RaCe systems, the results showed that Hero had mean deviation of 0.17 mm, RaCe, 0.13 mm and ProTaper, 0.27 mm. The ProTaper group showed a tendency for apical deviation or decline formation in all the canals. Hartmann et al., [1] showed that the manual technique had a mean deviation of 0.1 mm, oscillatory technique showed deviation of 0.37 mm and rotary ProTaper of 0.22 mm with a statistically significant difference among the groups.

The present study showed lower mean apical deviation when compared with the other studies. This is probably because the rotary and hybrid techniques were used up to the file corresponding to the diameter of file # 25, and other studies performed instrumentation up to the file corresponding to the diameter of file # 30. [1],[6],[10],[12],[13],[14] Therefore, it shows that instrumentation up to the file corresponding to the diameter of file #25 must be used with caution.

The values obtained with the study showed that the hybrid technique appeared to be more capable of cleaning the apical third of the root canal when compared with the techniques with rotary systems.

Recently, a Ni-Ti-Pathfile rotary system (Dentsply/Maillefer, Ballaigues, Switzerland) was developed for mechanical pre-enlargement or catheterism. It is composed of three instruments with constant taper of 0.02 mm and square section. This system was idealized to be used in combination with the universal ProTaper system. The manufacturer suggests that the PathFile be used first, immediately after using the K file #10 in the working length. One of the advantages of this new system is the improved design of the extremity that reduces risk of zip formation and apical deviation. [3],[5] In this study, it was observed that this technique provided minimal apical deviation, showing a mean of 0.08 mm. The facility to instrument the canals with the Universal ProTaper system after using the system PathFile may be also confirmed.


Based on the methodology used, it may be concluded that ProTaper, PathFile and Manual Hybrid-ProTaper technique were able to maintain the original internal root canal anatomy.


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