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Removal of root canal obstructions using pulsed Nd:YAG laser
International Congress Series 1248 (2003) 257 – 259
Removal of root canal obstructions using pulsed Nd:YAG laser Arata Ebihara *, Masaaki Takashina, Tomoo Anjo, Atsushi Takeda, Hideaki Suda Pulp Biology and Endodontics, Department of Restorative Sciences, Graduate School, Tokyo Medical and Dental University, 5-45, Yushima 1-chome, Bunkyo-ku, Tokyo 113-8549, Japan
Abstract The aim of this study was to investigate the ability and efficiency of the Nd:YAG laser to remove root canal obstructions. Crowns were removed from extracted human teeth and the samples were divided into three groups. In both the dowel core and the gutta-percha removal groups, the root canal was obturated with gutta-percha and sealer. In the dowel core removal group, a dowel core was subsequently placed. In the file removal group, a K file was intentionally fractured in the root canal. Nd:YAG laser irradiation was performed under water irrigation to remove dowel cores, gutta-percha, and K files. The Nd:YAG laser was able to remove all dowel cores and gutta-percha. Fractured files were successfully removed in five out of eight cases. The irradiation time in the dowel core, gutta-percha and file removal groups was 670, 19 and 317 s, respectively. The rate of postoperative increase of the canal area in the dowel core, gutta-percha and file removal groups was 28%, 6% and 62%, respectively. Since the laser irradiation is able to reach the deep portion of the root canal, with minimal risk of root fracture, it could be a useful tool for the removal of root canal obstructions. D 2003 Elsevier Science B.V. All rights reserved. Keywords: Nd:YAG laser; Removal; Root canal obstructions; Endodontics; Human teeth
1. Background Various methods have been advocated to remove root canal obstructions [1 – 3], but there is none currently available that can consistently remove such obstructions both easily
* Corresponding author. Tel.: +81-3-5803-5494; fax: +81-3-5803-5494. E-mail address: [email protected] (A. Ebihara). 0531-5131/03 D 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0531-5131(03)00038-4
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A. Ebihara et al. / International Congress Series 1248 (2003) 257–259
and safely. The aim of this study was to investigate the ability of Nd:YAG laser to successfully function in this capability.
2. Materials and methods Twenty-four extracted single-rooted human teeth were used. After removing the tooth crown, samples were randomly divided into three groups; dowel core, gutta-percha, and file removal groups. In the dowel core and the gutta-percha removal groups, the root canal was obturated with laterally condensed gutta-percha and sealer. In the dowel core removal group, a dowel core made of silver – palladium –copper –gold alloy was subsequently placed and cemented with glass-ionomer cement. In the file removal group, the tip of a 3mm-long K file was intentionally fractured in the root canal. Nd:YAG laser irradiation (output energy: 900 mJ and 10 pps, STATLase EPY, S.L.T. JAPAN, Japan) through an optical fiber (F = 400 Am) was performed under water irrigation to remove dowel cores, gutta-percha and K files, and the laser irradiation time was measured. Contact-microradiographs were taken both pre- and post-laser irradiation to evaluate the rate of postoperative increase of the root canal area. In addition, the root canal surface was observed by scanning electron microscopy (SEM) following laser irradiation.
3. Results The Nd:YAG laser was able to remove all dowel cores and gutta-percha. Fractured files were successfully removed from the root canal in five out of eight cases. The mean irradiation time in the dowel core, gutta-percha and file removal groups was, 670, 19 and 317 s, respectively. The rate of postoperative increase of the canal area in the dowel core, gutta-percha and file removal groups was 28%, 6% and 62%, respectively. SEM demonstrated that, at the irradiated area, the root canal surface exhibited a ‘‘moltenlava’’-like appearance, with the surface appearing melted and recrystallized.
4. Discussion and conclusions The advantage of using the Nd:YAG laser is that obstructions in the deeper portion of the root canal can be reached, a task which is not feasible with a high-speed cutting bur. Moreover, one can distinguish dentin from obstructions by the difference of acoustics produced by the two materials. Finally, since root fractures were not observed in any of the samples, the use of lasers in this application appears to carry a lesser risk of root fracture. In all groups, the canal area was increased postoperatively, signifying that not only the root canal obstruction but also root canal dentin was ablated by the laser. SEM observation indicated that the Nd:YAG laser had some effects on the canal wall dentin. Indeed, it has been previously reported that Nd:YAG laser irradiation might readily cause injury, either directly or indirectly, to the surrounding tissues [4,5]. Therefore, further studies are required before clinical application is recommended.
A. Ebihara et al. / International Congress Series 1248 (2003) 257–259
259
However, since the laser can reach the deep portion of the root canal, and does not appear to cause root fracture, the Nd:YAG laser could be a useful tool for the removal of root canal obstructions.
References [1] T. Yoshida, S. Gomyo, T. Itoh, T. Shibata, I. Sekine, An experimental study of the removal of cemented dowel-retained cast cores by ultrasonic vibration, J. Endod. 23 (1997) 239 – 241. [2] J.H. Altshul, G. Marshall, L.A. Morgan, J.C. Baumgartner, Comparison of dentinal crack incidence and of post removal time resulting from post removal by ultrasonic or mechanical force, J. Endod. 23 (1997) 683 – 686. [3] S. Cohen, R.C. Burns (Eds.), Pathways of the Pulp, 8th ed., Mosby, Missouri, 2002, pp. 903 – 910. [4] K. Koba, Y. Kimura, K. Matsumoto, T. Takeuchi, T. Ikarugi, T. Shimizu, A histopathological study of the effects of pulsed Nd:YAG laser irradiation on infected root canals in dogs, J. Endod. 25 (1999) 151 – 154. [5] J. Bahcall, P. Howard, L. Miserendino, H. Walia, Preliminary investigation of the histopathological effects of laser endodontic treatment on the periradicular tissues in dogs, J. Endod. 18 (1992) 47 – 51.
Removal of root canal obstructions using pulsed Nd:YAG laser Arata Ebihara *, Masaaki Takashina, Tomoo Anjo, Atsushi Takeda, Hideaki Suda Pulp Biology and Endodontics, Department of Restorative Sciences, Graduate School, Tokyo Medical and Dental University, 5-45, Yushima 1-chome, Bunkyo-ku, Tokyo 113-8549, Japan
Abstract The aim of this study was to investigate the ability and efficiency of the Nd:YAG laser to remove root canal obstructions. Crowns were removed from extracted human teeth and the samples were divided into three groups. In both the dowel core and the gutta-percha removal groups, the root canal was obturated with gutta-percha and sealer. In the dowel core removal group, a dowel core was subsequently placed. In the file removal group, a K file was intentionally fractured in the root canal. Nd:YAG laser irradiation was performed under water irrigation to remove dowel cores, gutta-percha, and K files. The Nd:YAG laser was able to remove all dowel cores and gutta-percha. Fractured files were successfully removed in five out of eight cases. The irradiation time in the dowel core, gutta-percha and file removal groups was 670, 19 and 317 s, respectively. The rate of postoperative increase of the canal area in the dowel core, gutta-percha and file removal groups was 28%, 6% and 62%, respectively. Since the laser irradiation is able to reach the deep portion of the root canal, with minimal risk of root fracture, it could be a useful tool for the removal of root canal obstructions. D 2003 Elsevier Science B.V. All rights reserved. Keywords: Nd:YAG laser; Removal; Root canal obstructions; Endodontics; Human teeth
1. Background Various methods have been advocated to remove root canal obstructions [1 – 3], but there is none currently available that can consistently remove such obstructions both easily
* Corresponding author. Tel.: +81-3-5803-5494; fax: +81-3-5803-5494. E-mail address: [email protected] (A. Ebihara). 0531-5131/03 D 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0531-5131(03)00038-4
258
A. Ebihara et al. / International Congress Series 1248 (2003) 257–259
and safely. The aim of this study was to investigate the ability of Nd:YAG laser to successfully function in this capability.
2. Materials and methods Twenty-four extracted single-rooted human teeth were used. After removing the tooth crown, samples were randomly divided into three groups; dowel core, gutta-percha, and file removal groups. In the dowel core and the gutta-percha removal groups, the root canal was obturated with laterally condensed gutta-percha and sealer. In the dowel core removal group, a dowel core made of silver – palladium –copper –gold alloy was subsequently placed and cemented with glass-ionomer cement. In the file removal group, the tip of a 3mm-long K file was intentionally fractured in the root canal. Nd:YAG laser irradiation (output energy: 900 mJ and 10 pps, STATLase EPY, S.L.T. JAPAN, Japan) through an optical fiber (F = 400 Am) was performed under water irrigation to remove dowel cores, gutta-percha and K files, and the laser irradiation time was measured. Contact-microradiographs were taken both pre- and post-laser irradiation to evaluate the rate of postoperative increase of the root canal area. In addition, the root canal surface was observed by scanning electron microscopy (SEM) following laser irradiation.
3. Results The Nd:YAG laser was able to remove all dowel cores and gutta-percha. Fractured files were successfully removed from the root canal in five out of eight cases. The mean irradiation time in the dowel core, gutta-percha and file removal groups was, 670, 19 and 317 s, respectively. The rate of postoperative increase of the canal area in the dowel core, gutta-percha and file removal groups was 28%, 6% and 62%, respectively. SEM demonstrated that, at the irradiated area, the root canal surface exhibited a ‘‘moltenlava’’-like appearance, with the surface appearing melted and recrystallized.
4. Discussion and conclusions The advantage of using the Nd:YAG laser is that obstructions in the deeper portion of the root canal can be reached, a task which is not feasible with a high-speed cutting bur. Moreover, one can distinguish dentin from obstructions by the difference of acoustics produced by the two materials. Finally, since root fractures were not observed in any of the samples, the use of lasers in this application appears to carry a lesser risk of root fracture. In all groups, the canal area was increased postoperatively, signifying that not only the root canal obstruction but also root canal dentin was ablated by the laser. SEM observation indicated that the Nd:YAG laser had some effects on the canal wall dentin. Indeed, it has been previously reported that Nd:YAG laser irradiation might readily cause injury, either directly or indirectly, to the surrounding tissues [4,5]. Therefore, further studies are required before clinical application is recommended.
A. Ebihara et al. / International Congress Series 1248 (2003) 257–259
259
However, since the laser can reach the deep portion of the root canal, and does not appear to cause root fracture, the Nd:YAG laser could be a useful tool for the removal of root canal obstructions.
References [1] T. Yoshida, S. Gomyo, T. Itoh, T. Shibata, I. Sekine, An experimental study of the removal of cemented dowel-retained cast cores by ultrasonic vibration, J. Endod. 23 (1997) 239 – 241. [2] J.H. Altshul, G. Marshall, L.A. Morgan, J.C. Baumgartner, Comparison of dentinal crack incidence and of post removal time resulting from post removal by ultrasonic or mechanical force, J. Endod. 23 (1997) 683 – 686. [3] S. Cohen, R.C. Burns (Eds.), Pathways of the Pulp, 8th ed., Mosby, Missouri, 2002, pp. 903 – 910. [4] K. Koba, Y. Kimura, K. Matsumoto, T. Takeuchi, T. Ikarugi, T. Shimizu, A histopathological study of the effects of pulsed Nd:YAG laser irradiation on infected root canals in dogs, J. Endod. 25 (1999) 151 – 154. [5] J. Bahcall, P. Howard, L. Miserendino, H. Walia, Preliminary investigation of the histopathological effects of laser endodontic treatment on the periradicular tissues in dogs, J. Endod. 18 (1992) 47 – 51.