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Cavity preparation for metal inlay by experimental tip for Er:YAG laser
International Congress Series 1248 (2003) 213 – 217
Cavity preparation for metal inlay by experimental tip for Er:YAG laser Tomofumi Kawakami a,*, Yuji Ibaraki a, Yasuhiko Nagai a, Koichi Matsuda a, Kenzo Kataoka b, Yoshihide Okagami b a Department of Operative Dentistry and Endodontology, School of Dentistry, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido 061-0293, Japan b Research and Development Department, J. Morita Mfg. Corp., 680 Higashi-Hamanami-cho, Fushimi, Kyoto 613-0022 Japan
Abstract The dental Er:YAG laser which is mainly used for dental hard tissue cutting was recently developed. In restorative dentistry, this laser has usually been used in composite resin restoration, but not for cast metal inlay restoration. This is because it is difficult to make the cavity form, such as retention form and convenience form, by using laser irradiation. At the 6th ISLD meeting, we reported an experimental chisel-shaped contact tip (ECSC tip) for use in cavity preparation for cast metal inlays. In this study, we examine a newly developed, modified experimental tip in inlay cavity preparation using an Erwin (ML22:HOYA & MORITA). This tip is composed of an arrangement of seven optical fibers having 0.2 or 0.3 mm diameter in a single row. The tooth-cutting efficacy of this tip was examined using extracted human and bovine teeth, and the irradiated sites were observed with SEM. The cutting efficacy of the experimental tip for both enamel and dentin was better than that of the ECSC tip. However, the surface flatness after cutting using experimental tip was poorer than the of the ECSC tip. It is suggested that inlay cavity preparation is possible using Erwin with this tip. D 2003 Published by Elsevier Science B.V. Keywords: Erbium YAG Laser; Cavity preparation; Contact tip; Chisel-shaped tip; Cast metal inlay
1. Background Lasers, including CO2, Nd:YAG and Er:YAG, are widely applied in the field of dentistry where they have been mainly used to carve the dental hard tissues. There may * Corresponding author. Tel./fax: +81-1332-31423. E-mail address: [email protected] (T. Kawakami). 0531-5131/03 D 2003 Published by Elsevier Science B.V. doi:10.1016/S0531-5131(03)00054-2
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still be some room for improvement of their cutting efficiency. We have previously developed a chisel-shaped contact tip (ECSC tip) in order to improve it (6th ISLD Conference, 2000). The ECSC tip had some problems in its application to the cavity preparation for cast metal inlay. We attempted to improve the ECSC tip and newly developed a chisel type chip, named B-200. In the present study, we examined the cutting efficiency of B-200 for bovine enamel and dentine. The data were compared with conventional or ECSC tips.
2. Materials and methods The details of a newly developed contact tip (B-200) is shown in Figs. 1 –4. The tip is composed of an arrangement of seven optical fibers having 0.2 –0.3 mm diameter in a single row. These fibers are fixed with epoxy resin and arranged in a single row as linear as possible, which is then covered with a thin metal pipe (Figs. 1 and 2). This feature allows it to change the pattern of irradiation energy. The Er:YAG laser (Erwin, ERW1; HOYA & MORITA, Japan) was used as a laser apparatus in this experiment. Conventional 600 Am contact tip and ECSC tip were also employed as well as B-200. The tooth-cutting efficiency of these tips was determined in enamel and dentine blocks (0.6 2.5 mm) as cutting materials made from extracted fresh bovine tooth. The laser irradiation was performed with the teeth under a water spray (1.5 –2.0 ml/min) at an energy setting of 50, 75, 100 or 125 mJ power and a pulse repetition rate of 10 pulses per second (pps). The samples were tested for each power condition. The volume of irradiation material and abraded area of sample were measured and calculated as the cutting efficiency (cm3/min).
Fig. 1. Contact tip (B-200).
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Fig. 2. Contact tip (B-200) method.
The surfaces of the irradiation areas were also observed with scanning electron microscope (SEM).
3. Results The results of measurements of the cutting efficiency are shown in Figs. 3 and 4. On enamel, the cutting efficiency of the B-200 tip was higher than the ECSC tip at all irradiation conditions. As compared with the conventional contact tip, the B-200 tip with low irradiation (50, 75 mJ) and high irradiation (100, 125mJ) showed about 1/2 cutting and 2/3 cutting efficiency, respectively.
Fig. 3. Enamel cutting efficiency.
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Fig. 4. Dentine cutting efficiency.
On dentine, the cutting efficiency of the B-200 tip was higher than the conventional contact tip under 25 mJ power condition. Under other power conditions, no difference in the cutting efficiency could be observed between B-200 and conventional tips. The cutting efficiencies of the B-200 tip for both enamel and dentine were higher than that of the ECSC tip under all power conditions. SEM pictures showed that the surface area irradiated was sharp (Fig. 5). Thermal denaturation was often observed under high power conditions.
Fig. 5. SEM view of the irradiated dentin with B-200 tip and ECSC tip.
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4. Conclusion In the present study, we developed a new type of chip named B-200 and showed its cutting efficiency for bovine enamel and dentine. The B-200 exhibits a high diffusion of the irradiation energy and was possible with use of a water spray. The cutting efficiency of B-200 was almost equal to the conventional model, indicating the highest cutting efficiency. The high crushing efficiency was also confirmed by the SEM observations. From these results, the B-200 may be a useful chip for cavity preparation for cast metal inlay [1].
Reference [1] Y. Ibaraki, Y. Nagai, et al., Application of erbium YAG laser to cavity preparation for cast metal inlay restoration, Higashi Nippon Dent. J. 18 (1) (1999) 25 – 32.
Cavity preparation for metal inlay by experimental tip for Er:YAG laser Tomofumi Kawakami a,*, Yuji Ibaraki a, Yasuhiko Nagai a, Koichi Matsuda a, Kenzo Kataoka b, Yoshihide Okagami b a Department of Operative Dentistry and Endodontology, School of Dentistry, Health Sciences University of Hokkaido, 1757 Kanazawa, Ishikari-Tobetsu, Hokkaido 061-0293, Japan b Research and Development Department, J. Morita Mfg. Corp., 680 Higashi-Hamanami-cho, Fushimi, Kyoto 613-0022 Japan
Abstract The dental Er:YAG laser which is mainly used for dental hard tissue cutting was recently developed. In restorative dentistry, this laser has usually been used in composite resin restoration, but not for cast metal inlay restoration. This is because it is difficult to make the cavity form, such as retention form and convenience form, by using laser irradiation. At the 6th ISLD meeting, we reported an experimental chisel-shaped contact tip (ECSC tip) for use in cavity preparation for cast metal inlays. In this study, we examine a newly developed, modified experimental tip in inlay cavity preparation using an Erwin (ML22:HOYA & MORITA). This tip is composed of an arrangement of seven optical fibers having 0.2 or 0.3 mm diameter in a single row. The tooth-cutting efficacy of this tip was examined using extracted human and bovine teeth, and the irradiated sites were observed with SEM. The cutting efficacy of the experimental tip for both enamel and dentin was better than that of the ECSC tip. However, the surface flatness after cutting using experimental tip was poorer than the of the ECSC tip. It is suggested that inlay cavity preparation is possible using Erwin with this tip. D 2003 Published by Elsevier Science B.V. Keywords: Erbium YAG Laser; Cavity preparation; Contact tip; Chisel-shaped tip; Cast metal inlay
1. Background Lasers, including CO2, Nd:YAG and Er:YAG, are widely applied in the field of dentistry where they have been mainly used to carve the dental hard tissues. There may * Corresponding author. Tel./fax: +81-1332-31423. E-mail address: [email protected] (T. Kawakami). 0531-5131/03 D 2003 Published by Elsevier Science B.V. doi:10.1016/S0531-5131(03)00054-2
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still be some room for improvement of their cutting efficiency. We have previously developed a chisel-shaped contact tip (ECSC tip) in order to improve it (6th ISLD Conference, 2000). The ECSC tip had some problems in its application to the cavity preparation for cast metal inlay. We attempted to improve the ECSC tip and newly developed a chisel type chip, named B-200. In the present study, we examined the cutting efficiency of B-200 for bovine enamel and dentine. The data were compared with conventional or ECSC tips.
2. Materials and methods The details of a newly developed contact tip (B-200) is shown in Figs. 1 –4. The tip is composed of an arrangement of seven optical fibers having 0.2 –0.3 mm diameter in a single row. These fibers are fixed with epoxy resin and arranged in a single row as linear as possible, which is then covered with a thin metal pipe (Figs. 1 and 2). This feature allows it to change the pattern of irradiation energy. The Er:YAG laser (Erwin, ERW1; HOYA & MORITA, Japan) was used as a laser apparatus in this experiment. Conventional 600 Am contact tip and ECSC tip were also employed as well as B-200. The tooth-cutting efficiency of these tips was determined in enamel and dentine blocks (0.6 2.5 mm) as cutting materials made from extracted fresh bovine tooth. The laser irradiation was performed with the teeth under a water spray (1.5 –2.0 ml/min) at an energy setting of 50, 75, 100 or 125 mJ power and a pulse repetition rate of 10 pulses per second (pps). The samples were tested for each power condition. The volume of irradiation material and abraded area of sample were measured and calculated as the cutting efficiency (cm3/min).
Fig. 1. Contact tip (B-200).
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Fig. 2. Contact tip (B-200) method.
The surfaces of the irradiation areas were also observed with scanning electron microscope (SEM).
3. Results The results of measurements of the cutting efficiency are shown in Figs. 3 and 4. On enamel, the cutting efficiency of the B-200 tip was higher than the ECSC tip at all irradiation conditions. As compared with the conventional contact tip, the B-200 tip with low irradiation (50, 75 mJ) and high irradiation (100, 125mJ) showed about 1/2 cutting and 2/3 cutting efficiency, respectively.
Fig. 3. Enamel cutting efficiency.
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Fig. 4. Dentine cutting efficiency.
On dentine, the cutting efficiency of the B-200 tip was higher than the conventional contact tip under 25 mJ power condition. Under other power conditions, no difference in the cutting efficiency could be observed between B-200 and conventional tips. The cutting efficiencies of the B-200 tip for both enamel and dentine were higher than that of the ECSC tip under all power conditions. SEM pictures showed that the surface area irradiated was sharp (Fig. 5). Thermal denaturation was often observed under high power conditions.
Fig. 5. SEM view of the irradiated dentin with B-200 tip and ECSC tip.
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4. Conclusion In the present study, we developed a new type of chip named B-200 and showed its cutting efficiency for bovine enamel and dentine. The B-200 exhibits a high diffusion of the irradiation energy and was possible with use of a water spray. The cutting efficiency of B-200 was almost equal to the conventional model, indicating the highest cutting efficiency. The high crushing efficiency was also confirmed by the SEM observations. From these results, the B-200 may be a useful chip for cavity preparation for cast metal inlay [1].
Reference [1] Y. Ibaraki, Y. Nagai, et al., Application of erbium YAG laser to cavity preparation for cast metal inlay restoration, Higashi Nippon Dent. J. 18 (1) (1999) 25 – 32.