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ORIGINAL ARTICLE
Year : 2017  |  Volume : 7  |  Issue : 2  |  Page : 110-114

Successive spreader insertion forces induced by undergraduate students during canal obturation


1 King Abdullah International Medical Research Centre, King Saud bin Abdulaziz University for Health Sciences, Restorative and Prosthetic Dental Sciences, College of Dentistry, Ministry of National Guard Health Affairs, Riyadh, Saudi Arabia
2 King Abdullah International Medical Research Centre, King Saud bin Abdulaziz University for Health Sciences, Restorative and Prosthetic Dental Sciences, College of Dentistry, Ministry of National Guard Health Affairs, Riyadh, Saudi Arabia; Department of Conservative Dentistry, Jordan University of Science and Technology, Irbid, Jordan
3 University Staff Clinics, College of Dentistry, King Saud University, 4Department of Dental, Security Forces Hospital, Riyadh, Saudi Arabia
4 Department of Dental, Security Forces Hospital, Riyadh, Saudi Arabia
5 King Abdullah International Medical Research Centre, King Saud bin Abdulaziz University for Health Sciences, College of Medicine, Ministry of National Guard Health Affairs, Riyadh, Saudi Arabia

Date of Web Publication25-Apr-2017

Correspondence Address:
Ahmed Jamleh
King Abdullah International Medical Research Centre, King Saud bin Abdulaziz University for Health Sciences, Restorative and Prosthetic Dental Sciences, College of Dentistry, National Guard Health Affairs, P. O. Box 22490, Riyadh 11426
Saudi Arabia
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/1658-5984.205133

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  Abstract 

Introduction: To investigate the forces induced by successive spreader insertions by undergraduate dental students.
Materials and Methods: Thirty-eight artificial resin teeth (Real-T Endo, Acadental, Lenexa, KS, USA) were used. After canal preparation, the teeth were distributed equally into male and female students to perform canal obturation with the lateral compaction technique. A force gauge (M5-20 Advanced Digital Force Gauge; Mark-10 Corporation, NY, USA) was used for recording the spreader insertion force. Linear mixed model was used to assess the effects of both gender and repeated measures of spreader insertion on spreader penetration forces during canal obturation at a significance level of 5%.
Results: The mean maximum forces measured were in the range of 1.13 ± 0.44–1.67 ± 0.64 kg. There was a significant difference between the five insertion times (P = 0.003), and the initial three insertion times were lower than the fourth and fifth times. Although female students apply more force, there was no significant difference when compared to that of male students (P = 0.136).
Conclusion: The force gauge device can be used as educational tool to measure the force applied during canal obturation. Although the forces applied by female students were higher than the male students, they were all considered safe.

Keywords: Canal obturation, lateral compaction, penetration force, undergraduate students


How to cite this article:
Jamleh A, Alfouzan K, Awawdeh L, Alfadley A, Ibrahim N, Alhijji S, Masuadi E. Successive spreader insertion forces induced by undergraduate students during canal obturation. Saudi Endod J 2017;7:110-4

How to cite this URL:
Jamleh A, Alfouzan K, Awawdeh L, Alfadley A, Ibrahim N, Alhijji S, Masuadi E. Successive spreader insertion forces induced by undergraduate students during canal obturation. Saudi Endod J [serial online] 2017 [cited 2023 Feb 1];7:110-4. Available from: https://www.saudiendodj.com/text.asp?2017/7/2/110/205133


  Introduction Top


Controlling pulp infection is fundamental to have successful root canal treatment.[1] The key goals of root canal treatment are to effectively clean and shape the root canal space and to adequately seal the canal by obturating materials to provide or maintain healthy periapical tissues.[2]

Canal obturation is considered a crucial step of root canal treatment where fluid-tight seal should be achieved in three dimensions to prevent ingress of fluids and bacteria to and from the canal system, improving the treatment outcome.[3],[4] Conventionally, the canal obturation is undertaken with core obturation materials such as gutta-percha (GP) along with a sealer.[5] Numerous methods are used to place the obturating materials in ways to maximize their distribution through the length of the canal.[6],[7],[8],[9] Lateral compaction technique is the most used and taught root canal obturation technique worldwide,[10] whereby a master GP cone is placed, and a cone-shaped spreader is inserted beside the main cone to compact the cone laterally and vertically to the working length. This generates a space to insert an accessory GP cone. The lateral compaction is relatively simple to carry out and is considered the golden obturation method against which newly introduced techniques are compared.[11],[12],[13]

Theoretically, inserting the spreader with high forces could effectively compact GP and provide spaces to be successfully filled with lesser voids. However, the lateral compaction force has been recognized as being a potential cause of dentinal damage that creates tensile stress on the root canal walls and mechanically alters the dentin structure.[14],[15],[16],[17] The altered dentin varies from small defects and cracks to root fracture.[14],[18],[19] Walton et al.[20] studied the root fracture patterns by measuring the generated strains during lateral compaction and speculated that spreader force inside the canal would develop fracture.

During lateral compaction, the spreader insertion is repeated until no further space can be provided. Previous studies measured spreader force of the first insertion during lateral compaction and found it in the range of 0.9–3.0 kg.[6],[21] However, measuring the forces of successive spreader insertions till the canal is fully obturated might address how much forces are clinically applied. Therefore, the aim of this study was to investigate the forces obtained from five successive spreader insertions by undergraduate students.


  Materials and Methods Top


Tooth preparation

Thirty-eight artificial resin mandibular premolar teeth with single canals (T29, Real-T Endo, Acadental, Lenexa, KS, USA) were used. Access cavity was performed by one operator. The straight-line access was achieved using SX file (ProTaper Universal, Dentsply Maillefer, Ballaigues, Switzerland) 5 mm below the orifice.

Canal preparation

The working length was determined by inserting a size 10 K-file into the root canal until the tip of the instrument was flush with the apical foramen. The distance from the reference plane in the occlusal direction to this flush level minus 1 mm was defined as the working length of the root canal.

Canal preparation was performed by an experienced operator with ProTaper Next rotary system (Dentsply Maillefer, Ballaigues, Switzerland) according to the recommended speed and torque by the use of a digital torque control motor (DTC, SybronEndo, Orange, CA, USA). The X1 (17 04), X2 (25 06), and X3 (30 07) instruments were used sequentially with a slight in-and-out movement of 1-2 mm up to the working length. Then, apical preparation was further enlarged with hand K-file sizes 35 and 40. The canal was irrigated with 1% sodium hypochlorite after each instrument use then dried with absorbent paper points.

Canal obturation

The prepared canals were distributed into two groups: 19 male and 19 female students. The sophomore students were in the level where they will start treating patients in the next academic semester. They had attended preclinical endodontic course and received lectures on how to competently perform root canal treatment. Since the presence of tug-back indicates good GP adaptation inside the root canal,[22] a series of pilot cones was tested to select an appropriate size and taper. Master GP cone size 40 and taper 02 was used along with five fine accessory cones.

AH-26 sealer (Dentsply, Maillefer, Switzerland) was mixed and placed into the canal, and GP cone, size 40 02 taper, was placed to the working length. Afterwards, the students were instructed to insert stainless steel finger spreader size Fine (Miltex Integra, PA, USA) along the buccal wall of the canal beside the master GP cone, parallel to the long axis of the root canal, and perpendicular to the testing stage. Then, the spreader was removed, and the space provided was filled with an accessory GP cone size Fine. The spreader was reinserted four times more till the canal was fully filled with GP.

Vertical force measurements

A force gauge (M5-20 Advanced Digital Force Gauge; Mark-10 Corporation, NY, USA) with capacity of 10 kg force was used for recording the spreader penetration force applied during canal obturation. The tooth was set on a fixed stage, and the accuracy of the force gauge was checked by loading it with a calibrated weight. The force gauge was set at zero before each use. The force gauge outputs, represented as spreader penetration forces during obturation, were obtained by MESUR Lite software (Mark-10 Corporation, NY, USA).

Statistical analysis

The effects of both gender and repeated measures of spreader insertion on spreader penetration forces were analyzed by linear mixed model. All statistical analyses were performed using SPSS software version 22 (SPSS Inc., Chicago, IL, USA) at a significance level of 5%.


  Results Top


The mean maximum forces measured during spreader penetrations were in the range of 1.13 ± 0.44–1.67 ± 0.64 kg.

The linear mixed model was used to assess the effect of both gender and the repeated measure of insertions time on the maximum forces measured during spreader penetrations [Table 1]. In term of the covariance matrix of the repeated measure, there was no significant difference between identity model and the diagonal model (P = 0.884, likelihood ratio test) while there was a significant difference between the diagonal and unstructured model (P < 0.001) which suggests that an unstructured covariance matrix should be used in the model. There was no interaction between gender and insertion time (P = 0.362) [Figure 1], thus it was removed from the model. In term of the insertion time, there was a significant difference between the five times (P = 0.003). The first time was significantly lower than the fourth and fifth times (P = 0.003 and 0.022, respectively). The second time was significantly lower than the fourth (P = 0.031). Moreover, the third time was significantly lower than the fourth and fifth times (P = 0.001 and 0.018, respectively).
Table 1: Estimates of fixed effects of gender and insertion time on the maximum forces measured during spreader penetrations

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Figure 1: Estimated marginal mean of the fitted model

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Although female students tended to apply more spreader forces, there was no significant difference when compared to male students (P = 0.136) [Figure 1].


  Discussion Top


Utilizing the force gauge device to measure the magnitude of vertical forces during endodontic preparation was shown to be applicable.[23] This in vitro study investigated the magnitude of vertical forces used to successfully insert the spreader till the canal was adequately filled. The lateral compaction was adopted since it is the taught obturation technique to our undergraduate students and the most common obturation technique worldwide.[10],[12] The spreader insertion peak forces generated by male and female students during the lateral compaction were in the range of 1.13 ± 0.44–1.67 ± 0.64 kg, where the female students tended to apply more force. Moreover, the spreader required comparable forces in the initial insertion times, which were less than those measured in the fourth and fifth insertion times.

Prevention of dentinal defect from the forces applied during canal obturation has been considered a critical issue in endodontics.[24] The lateral compaction technique necessitates inserting the endodontic spreader many times till the canal is fully filled with GP cones. This illustrates that the more spreader with GP cone insertion is performed, the less canal space will result, and therefore more intracanal force might develop inducing higher lateral forces on dentin structure. Nevertheless, the measured insertion forces were considered safe and within the range of other studies where the peak forces induced by clinicians did not exceed 3 kg.[6],[21] Previous crack studies revealed that the forces required to cause root fracture were more than 3.3 kg,[15],[17],[18],[25],[26] indicating that the students induced safe forces even with the many successive spreader insertions. However, Holcomb et al.[27] observed root fracture at a low spreader force of 1.5 kg. This can be explained by their use of mandibular incisors and differences in experimental procedure.

Earlier studies showed that endodontic procedures strained and expanded the root dentin structure.[18],[19],[28],[29] Moreover, the relationship between lateral compaction and root fracture has been proposed.[6],[19],[30] Therefore, the use of light forces to insert the spreader alongside the GP cone is recommended. Because hand spreader encourages higher compaction forces than finger spreader,[19] the latter was utilized in this study. Tooth fracture might be the result of maximum tensile stress over the root canal surface.[31] Finite element analysis studies stated that lateral compaction poses a threat to the long-term stability of dentin due to the identification of stress areas that may predispose a tooth to structural failure during compaction forces.[16],[31] This increased stress creates root distortion and the potential for vertical root fracture.[15],[26],[32],[33],[34] With its viscoelastic properties, dentin deforms under force loading and returns slowly to normal once unloaded.[28],[29],[35] This slow recovery permits strain accumulation with a gradual increase in strain offset to a level that obturating the canal immediately after canal preparation might cause fracture even with low forces.

Previous studies measured the spreader insertion force by axial static loads operated through Instron testing machines.[6],[15],[17],[18],[21],[25],[26] However, the present study utilized a force gauge with a fixed stage, able to measure the apically directed forces during spreader insertion. This would mimic the clinical setting by allowing the students to obturate the canals with their own applied force with no prior adjustment.

It is noteworthy that the female students applied more force to insert the spreader. A significant relationship between gender and academic performance of dental students has been reported, where female dental students outperform males in dentistry courses.[36] It might be explained by the fact that female dental students try their best to compact GP cones in an attempt to have good quality obturation.


  Conclusion Top


Within the limitations of this study, the force gauge device can be used to determine the force applied during canal obturation. As educational tool, it can be utilized to calibrate student's performance to avoid excessive force that might lead to root damage. The more times the spreader is inserted the more force it will exhibit. Moreover, compared to the male students, the female students applied more obturation forces.

Acknowledgment

This work was supported by a research grant (RC/16/069/R) from King Abdullah International Medical Research Center and National Guard Health Affairs, Riyadh, Kingdom of Saudi Arabia.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
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