|Year : 2012 | Volume
| Issue : 2 | Page : 116-119
Endodontic retreatment: Rotary versus hand instrumentation: An in vitro study
Sujana Varri1, Ram S Chukka1, Nagesh Bolla1, Sharat R Kavuri1, Surya Kumari2
1 Department of Conservative Dentistry, Sibar Institute of Dental Sciences, Guntur, Andhra Pradesh, India
2 Department of Conservative Dentistry, MNR Institute of Dental Sciences, Hyderabad, Andhra Pradesh, India
|Date of Web Publication||11-Jul-2012|
Department of Conservative Dentistry, Sibar Institute of Dental Sciences, Guntur, Andhra Pradesh
Source of Support: None, Conflict of Interest: None
Objective: The present study has probed the effectiveness of nickel titanium rotary instruments (ProTaper) and hand instruments in the retrieval of gutta-percha and sealer using Hemo-De as a solvent.
Materials and Methods: Thirty extracted, single-rooted anterior teeth were instrumented and obturated with gutta-percha and zinc oxide sealer using the lateral condensation method. They were distributed into 3 groups of 10 each. Retreatment for group A was done using NiTi ProTaper alone, for group B using ProTaper and Hemo-De (d-limonene), and for group C using hand files with Hemo-De. The teeth were then split longitudinally into two halves. The remaining gutta-percha or sealer on the root canal wall in the cervical, middle, apical thirds, and the whole canals was visually scored with the aid of a stereo microscope.
Results: The results have showed that the mean scores in groups A and B were generally lower than those for group C. Mean scores of the apical thirds tended to be higher (worse) than the middle and cervical thirds except in group A.
Conclusion: ProTaper with or without Hemo-De seems to be a viable alternative retreatment method.
Keywords: Gutta-percha solvents, Hemo-De, retreatment, rotary instruments
|How to cite this article:|
Varri S, Chukka RS, Bolla N, Kavuri SR, Kumari S. Endodontic retreatment: Rotary versus hand instrumentation: An in vitro study. J NTR Univ Health Sci 2012;1:116-9
|How to cite this URL:|
Varri S, Chukka RS, Bolla N, Kavuri SR, Kumari S. Endodontic retreatment: Rotary versus hand instrumentation: An in vitro study. J NTR Univ Health Sci [serial online] 2012 [cited 2019 Dec 14];1:116-9. Available from: http://www.jdrntruhs.org/text.asp?2012/1/2/116/98358
| Introduction|| |
Nonsurgical endodontic retreatment requires regaining of access to the root canal system through the complete removal of the endodontic obturating material. This enables thorough chemomechanical reinstrumentation and disinfection of the root canal system, which are prerequisites for successful retreatment.  Guttta-percha removal can be effected by endodontic hand files, heat-carrying instruments, ultrasonic devices, and rotary instruments with or without the aid of solvents.  Chloroform and xylene were the most widely used solvents. However, their possible damage to periapical tissues and systemic toxicity cannot be overlooked.  In recent years, nickel titanium files have been used increasingly in root canal preparation due to their increased flexibility. 
The purpose of this study is to compare the effectiveness in retreating gutta-percha-obturated root canals using ProTaper with and without Hemo-De and hand files with Hemo-De (d-limonene).
| Materials and Methods|| |
Thirty freshly extracted, single-canal, human anterior teeth were collected, with the soft tissue and calculus mechanically removed, and stored in saline until further use. Access cavity preparation was made on each tooth; working lengths were determined radiographically 1 mm short of the root apex. Root canal preparation was done by the stepback technique using K-files till size 40. Three percent sodium hypochlorite irrigation was used during cleaning and shaping. The canals were laterally condensed using size 40 master gutta-percha cones and accessory cones using the zinc oxide sealer. A heated plugger was used to remove the gutta-percha to the level of the cementoenamel junction. The access cavities were temporized with cavit. Teeth were then radiographed to confirm the adequacy of the root canal obturation. All the teeth were then stored in saline for 1 month.
All the teeth were divided into 3 groups of 10 teeth each. The temporary restorations were removed; the cervical part of gutta-percha was removed using a heated plugger and the remaining gutta-percha and sealer were removed according to one of the following methods:
- Group A (ProTaper rotary instruments alone; Dentsply Mallifer) - as suggested by the manufacturer, the gutta-percha was removed by following sequence using light apical pressure. Finishing files no. 3 (ISO size 30), no. 2 (ISO size 25), and no. 1 (IS0 size 20) were used in a crowndown technique to remove the gutta-percha until the working length was reached. Finishing files no. 2 and no. 3 were used again to the working length to complete gutta-percha removal and cleaning of the canal walls.
- Group B (Protaper NiTi rotary instruments and Hemo-De) - after removing the cervical part of gutta-percha with the heated plugger, Hemo-de in increments of 0.05 ml was injected into canals to soften the gutta-percha. Finishing files no. 3 (ISO size 30), no. 2 (ISO size 25), and no. 1 (ISO size 20) were used in a crowndown fashion to remove gutta-percha.
- Group C (conventional hand files with Hemo-De) - increments of 0.05 ml of Hemo-De were injected into the canals to soften the gutta-percha. Hedstrom files starting from size 25 up to size 45 were used for the removal of gutta-percha. The instrumentation was completed with the file size 60. During the retreatment, root canals were constantly irrigated with 3% sodium hypochlorite.
The teeth were grooved vertically and split into two halves with a diamond disc. They were then coded and attached to a glass slide. The specimens were randomly arranged to avoid examiners' bias. The scoring was done by three independent examiners using a stereo microscope at a ×4 magnification.
The amount of the residual root canal filling in the three regions and in the whole canals was scored for both halves of the split teeth.
Evaluation scale  scores were as follows:
- Score 0 - no or negligible
- Score 1 - mild
- Score 2 - moderate
- Score 3 - severe.
The degree of the agreement of the scores obtained by the three examiners was assessed by ANOVA. The whole scores of the three groups and the three levels of the same group were compared by the Kruskal-Wallis test.
| Results|| |
The scores and the mean scores for the amounts of residual gutta-percha or sealer in the whole canals and at the three canal levels in the three retreatment groups are presented in [Table 1] and [Table 2]. The whole canal mean score for group A (1.10) was lower than that of group B (1.40) and group C (1.63; [Table 1]). There was a statistical difference between group A and group C (P = 0.023). For group A, the mean score of the residual root canal filling material was higher in the cervical level (1.60) than the middle (1.00) and the apical levels of canals (1.20). For groups B and C, the apical canal levels had higher mean scores than the cervical and middle canal levels.
|Table 1: Frequency of scores for the residual root canal filling material by the three examiners|
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|Table 2: Mean scores of the residual root canal filing material after retreatment|
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The retreatment time of group A (178.3 s) and group B (160.3 s) was shorter than that of group C (183.4 s) with the time difference between groups B and C being significant (P = 0.034).
| Discussion|| |
Endodontic retreatment is indicated when initial root canal treatment has failed, and the problem may be corrected through better canal debridement and obturation. Whenever feasible, nonsurgical retreatment should be performed over surgery. Different types of gutta-percha solvents were used to facilitate the removal of gutta-percha from the root canal system. Chloroform and xylene were the most commonly used solvents.  Chloroform is the preferred solvent with the advantage of dissolving and evaporating fast with a vapour pressure of 195 mmHg.  But the main disadvantages of chloroform are its suspected carcinogenicity and damage caused to the periapical tissues. Xylene has the property of evaporating slowly and is suitable for the removal of gutta-percha. But it too has the disadvantage of damaging the periapical tissues. So there is always a search for safe and efficient chloroform and xylene substitutes. Hemo-De is a naturally occurring compound derived from citrus fruits with the active ingredient d-limonene (4-isopropyl-1-methyl 1- cyclohexane). It is insoluble in water, evaporates slowly without any remaining residues, and is recognized as a safe material by the Food and Drug Administration (FDA). 
The conventional removal of gutta-percha using hand files is a tedious procedure. Barrieshi-Nusair reported NiTi rotary removal of gutta-percha for retreatment.  Wilcox et al. in 1987 reported that traces of gutta-percha and sealer remained regardless of the technique of reinstrumentation.  In the present study also, none of the samples had a score of 0. Glosson and Haller showed that the time of retreatment using NiTi rotary is faster than K-flex files. ,
In our present study, the mean time taken to prepare the root canal using ProTaper was less than that with hand files (H-files). Retreatment using ProTaper rotary files with or without the gutta-percha solvent (group A and group B, respectively) was overall faster than that with hand files with the gutta-percha solvent (Gr-C) [Table 3].
| Conclusion|| |
Under the present experimental conditions, rotary NiTi files seem to be a viable alternative retreatment technique for gutta-percha-obturated root canals with or without the use of gutta-percha solvent. Moreover, Hemo-De showed to be an effective and safe alternative to xylene and chloroform as a gutta-percha solvent.
Though better results have been noticed in this study, further investigation of the use of NiTi files is needed on the extent of the extrusion of root canal filling materials, and effectiveness of the removal of gutta-percha in curved canals and in teeth obturated with different techniques.
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[Table 1], [Table 2], [Table 3]