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Piezosurgery®: an ultrasound device for cutting bone and its use and limitations in maxillofacial surgery
British Journal of Oral and Maxillofacial Surgery (2004) 42, 451—453
SHORT COMMUNICATION
Piezosurgery® : an ultrasound device for cutting bone and its use and limitations in maxillofacial surgery Georg Eggers*, Johannes Klein, Julia Blank, Stefan Hassfeld Department of Oral and Cranio-Maxillofacial Surgery, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany Accepted 30 April 2004 Available online 28 July 2004
KEYWORDS Piezosurgery; Maxillofacial surgery; Bone cutting; Ultrasonic vibration
Summary Piezosurgery uses modulated ultrasonic vibration to allow controlled cutting of bony structures. Delicate bony structures can be cut easily and with great precision, without destruction of soft tissue. We have found this device useful when exact cutting of thin bones is essential. However, it is of only limited use in cutting thick bones and in regions with limited access. © 2004 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
Introduction Ultrasound has been used for decades to cut tissue, and commercially available systems for ultrasonic cutting of soft tissue are used in various medical disciplines and environments.1,2 Ultrasonic cutting of bone is feasible3 and alveolar bone that had been cut ultrasonically healed uneventfully.4
Technique Piezosurgery® (Mectron, Carasco, Italy) is a recently developed system for cutting bone with microvibrations. These are created by the piezoelectric effect: certain ceramics and crystals deform when an electric current is passed across them, resulting in oscillations of ultrasonic frequency. *Corresponding author. Tel.: +49 6221 56 7332; fax: +49 6221 56 4222. E-mail address: [email protected] (G. Eggers).
The equipment (Fig. 1) consists of a piezoelectric handpiece and a foot switch that are connected to a main unit, which supplies power and has holders for the handpiece and irrigation fluids. It contains a peristaltic pump for cooling with a jet of solution that discharges from the insert with an adjustable flow of 0—60 ml/min and removes detritus from the cutting area. The settings of power and frequency modulation of the device can be selected on a control panel with a digital display and a keypad according to the planned task. The unit uses a frequency of 25—29 kHz. In ‘‘boosted’’ mode, a digital modulation of this oscillation produces an alternation of high frequency vibrations with pauses at a frequency of up to 30 Hz. This alternation prevents the insert from impacting the bone and avoids overheating while maintaining optimum cutting capacity.5 For the handpiece several autoclavable tooltips, called ‘‘inserts’’, are available (Fig. 2). Some are coated with titanium or diamonds in various grades. The microvibrations that are created in the piezoelectric handpiece cause the inserts to move between 60 and 210 m, providing the
0266-4356/$ — see front matter © 2004 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.bjoms.2004.04.006
452
G. Eggers et al.
Procedures
Figure 1 The Mectron Piezosurgery system: (A) main unit with panel (I), peristaltic pump (II), socket for connector to handpiece (III); and (B) handpiece with saw insert.
In craniofacial surgery, we used the system in fronto-orbital advancement operations in children. We cut the calvarial bones in two stages. Firstly, we cut the calvarium to remove parts for later reposition. The cutting speed was dependent on the thickness of the bone. When the bones were more than about 3 mm wide, the cutting was slow but precise and without laceration of the dura mater. The tool was also used to cut the removed bone before replantation. Here the system proved to be particularly useful. It was possible, even in the thin bone of a child’s calvarium, to cut the inner cortical layer selectively without damaging the outer cortical bone. The bone could then be bent into shape before fixation with microplate osteosynthesis without breaking. The number of fragments and the amount of osteosynthetic material was therefore reduced, which saved time and reduced costs. In sinus-lift operations it was easy to cut a bony window into the maxilla without lacerating the mucosa of the maxillary sinus. The cut was thin, which
handpiece with power exceeding 5 W.5 The instrument was originally designed for augmentation in implant operations, including sinus lift6 and ridge expansion.7 For the cutting of bone in maxillofacial operations, the most efficient setting is boosted mode with maximum irrigation. The handpiece is guided over the bone firmly, but without excessive force. The sound of the cutting can be used as acoustic feedback for the force to be used. During operations, it is important to pay attention to irrigation to avoid heating of the bone. After prolonged cutting the handpiece will warm and a short pause may be advisable to let the handpiece cool down.
Figure 2 A selection of available inserts, from left to right: (A) flat scalpel, diamond tipped, titanium nitride-coated surface; (B) cone compressor, flat, blunt; (C) bone harvester, titanium nitride-coated surface; and (D) sharp tipped saw, titanium nitride-coated surface.
Figure 3 Accurate osteotomy of the buccal cortical bone of mandible in a case of apical odontoma: (A) cutting the cortical bone with the Piezosurgery handpiece; and (B) osteotomy completed.
Piezosurgery in maxillofacial surgery
453 lift, a specially designed insert could be used to collect material from the bone surface. When gently moved over the surface, small deposits of bone particles accumulated on the surface and could easily be collected with a small curette. Currently, we are doing an electron microscopic study in cadaveric bones, which suggests that the quality of cuts by Piezosurgery compares favourably with those using conventional instruments (Fig. 4).
Figure 4 Electron micrographs of bone surfaces after different cutting devices, from left to right: (A) Piezosurgery; (B) Lindemann bone cutter; and (C) oscillating saw.
reduced the loss of bony tissue. The mucosa could be peeled off the bone with a cone compressor, causing no damage. However, the access to the posterior regions of a LeFort osteotomy of the maxilla was extremely difficult. A common problem in the surgical removal of osteosynthetic material is the formation of callus that covers plates and screws and makes removal difficult. The Piezosurgery system allowed us to remove callus from titanium osteosynthetic material quickly. In particular, it was possible to remove the callus from the slots of screws without damaging them. Screwdrivers could then be attached. In osteotomies and biopsies of bone it was possible to place exact cuts at the desired location of the bony surface. In particular, it was possible to cut the bone between teeth precisely at the desired angle (Fig. 3A and B). However, when deep cuts into the bone were necessary, the system was less efficient. While the cutting speed decreased temperatures rose, so pauses were necessary to let the system cool down. In these cases, the combination of Piezosurgery for the initial incision and a chisel for the final osteotomy of the bone was useful. In cases where it is necessary to obtain autologous material to fill bony defects, such as in sinus
Discussion The manufacturer claims that bone can be cut precisely without damage to soft tissue and with little bleeding (Handbook, Mectron S.r.l., Carasco, Italy, 2002). The system fulfilled these promises for us.
References 1. Sherman JA, Davies HT. Ultracision® : the harmonic scalpel and its possible uses in maxillofacial surgery. Br J Oral Maxillofac Surg 2000;38:530—2, doi: 10.1054/bjom.2000.0502. 2. Lee SJ, Park KH. Ultrasonic energy in endoscopic surgery. Yonsei Med J 1999;40:545—9. 3. Horton JE, Tarpley TM, Jacoway JR. Clinical applications of ultrasonic instrumentation in the surgical removal of bone. Oral Surg Oral Med Oral Pathol 1981;51:236—42. 4. Horton JE, Tarpley TM, Wood LD. The healing of surgical defects in alveolar bone produced with ultrasonic instrumentation, chisel, and rotary bur. Oral Surg Oral Med Oral Pathol 1975;39:536—46. 5. Vercellotti T, Russo C, Gianotti S. A new piezoelectric ridge expansion technique in the lower arch. A case report. World Dent 2001;1(2). http://www.worlddent. com/2001/05/articles/vercellotit.xml. 6. Vercellotti T, de Paoli S, Nevins M. The piezoelectric bony window osteotomy and sinus membrane elevation: introduction of a new technique for simplification of the sinus augmentation procedure. Int J Periodontics Restor Dent 2001;21:561—7. 7. Vercellotti T. Piezoelectric surgery in implantology: a case report–—a new piezoelectric ridge expansion technique. Int J Periodontics Restor Dent 2000;4:359—65.
SHORT COMMUNICATION
Piezosurgery® : an ultrasound device for cutting bone and its use and limitations in maxillofacial surgery Georg Eggers*, Johannes Klein, Julia Blank, Stefan Hassfeld Department of Oral and Cranio-Maxillofacial Surgery, Heidelberg University Hospital, Im Neuenheimer Feld 400, 69120 Heidelberg, Germany Accepted 30 April 2004 Available online 28 July 2004
KEYWORDS Piezosurgery; Maxillofacial surgery; Bone cutting; Ultrasonic vibration
Summary Piezosurgery uses modulated ultrasonic vibration to allow controlled cutting of bony structures. Delicate bony structures can be cut easily and with great precision, without destruction of soft tissue. We have found this device useful when exact cutting of thin bones is essential. However, it is of only limited use in cutting thick bones and in regions with limited access. © 2004 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
Introduction Ultrasound has been used for decades to cut tissue, and commercially available systems for ultrasonic cutting of soft tissue are used in various medical disciplines and environments.1,2 Ultrasonic cutting of bone is feasible3 and alveolar bone that had been cut ultrasonically healed uneventfully.4
Technique Piezosurgery® (Mectron, Carasco, Italy) is a recently developed system for cutting bone with microvibrations. These are created by the piezoelectric effect: certain ceramics and crystals deform when an electric current is passed across them, resulting in oscillations of ultrasonic frequency. *Corresponding author. Tel.: +49 6221 56 7332; fax: +49 6221 56 4222. E-mail address: [email protected] (G. Eggers).
The equipment (Fig. 1) consists of a piezoelectric handpiece and a foot switch that are connected to a main unit, which supplies power and has holders for the handpiece and irrigation fluids. It contains a peristaltic pump for cooling with a jet of solution that discharges from the insert with an adjustable flow of 0—60 ml/min and removes detritus from the cutting area. The settings of power and frequency modulation of the device can be selected on a control panel with a digital display and a keypad according to the planned task. The unit uses a frequency of 25—29 kHz. In ‘‘boosted’’ mode, a digital modulation of this oscillation produces an alternation of high frequency vibrations with pauses at a frequency of up to 30 Hz. This alternation prevents the insert from impacting the bone and avoids overheating while maintaining optimum cutting capacity.5 For the handpiece several autoclavable tooltips, called ‘‘inserts’’, are available (Fig. 2). Some are coated with titanium or diamonds in various grades. The microvibrations that are created in the piezoelectric handpiece cause the inserts to move between 60 and 210 m, providing the
0266-4356/$ — see front matter © 2004 The British Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.bjoms.2004.04.006
452
G. Eggers et al.
Procedures
Figure 1 The Mectron Piezosurgery system: (A) main unit with panel (I), peristaltic pump (II), socket for connector to handpiece (III); and (B) handpiece with saw insert.
In craniofacial surgery, we used the system in fronto-orbital advancement operations in children. We cut the calvarial bones in two stages. Firstly, we cut the calvarium to remove parts for later reposition. The cutting speed was dependent on the thickness of the bone. When the bones were more than about 3 mm wide, the cutting was slow but precise and without laceration of the dura mater. The tool was also used to cut the removed bone before replantation. Here the system proved to be particularly useful. It was possible, even in the thin bone of a child’s calvarium, to cut the inner cortical layer selectively without damaging the outer cortical bone. The bone could then be bent into shape before fixation with microplate osteosynthesis without breaking. The number of fragments and the amount of osteosynthetic material was therefore reduced, which saved time and reduced costs. In sinus-lift operations it was easy to cut a bony window into the maxilla without lacerating the mucosa of the maxillary sinus. The cut was thin, which
handpiece with power exceeding 5 W.5 The instrument was originally designed for augmentation in implant operations, including sinus lift6 and ridge expansion.7 For the cutting of bone in maxillofacial operations, the most efficient setting is boosted mode with maximum irrigation. The handpiece is guided over the bone firmly, but without excessive force. The sound of the cutting can be used as acoustic feedback for the force to be used. During operations, it is important to pay attention to irrigation to avoid heating of the bone. After prolonged cutting the handpiece will warm and a short pause may be advisable to let the handpiece cool down.
Figure 2 A selection of available inserts, from left to right: (A) flat scalpel, diamond tipped, titanium nitride-coated surface; (B) cone compressor, flat, blunt; (C) bone harvester, titanium nitride-coated surface; and (D) sharp tipped saw, titanium nitride-coated surface.
Figure 3 Accurate osteotomy of the buccal cortical bone of mandible in a case of apical odontoma: (A) cutting the cortical bone with the Piezosurgery handpiece; and (B) osteotomy completed.
Piezosurgery in maxillofacial surgery
453 lift, a specially designed insert could be used to collect material from the bone surface. When gently moved over the surface, small deposits of bone particles accumulated on the surface and could easily be collected with a small curette. Currently, we are doing an electron microscopic study in cadaveric bones, which suggests that the quality of cuts by Piezosurgery compares favourably with those using conventional instruments (Fig. 4).
Figure 4 Electron micrographs of bone surfaces after different cutting devices, from left to right: (A) Piezosurgery; (B) Lindemann bone cutter; and (C) oscillating saw.
reduced the loss of bony tissue. The mucosa could be peeled off the bone with a cone compressor, causing no damage. However, the access to the posterior regions of a LeFort osteotomy of the maxilla was extremely difficult. A common problem in the surgical removal of osteosynthetic material is the formation of callus that covers plates and screws and makes removal difficult. The Piezosurgery system allowed us to remove callus from titanium osteosynthetic material quickly. In particular, it was possible to remove the callus from the slots of screws without damaging them. Screwdrivers could then be attached. In osteotomies and biopsies of bone it was possible to place exact cuts at the desired location of the bony surface. In particular, it was possible to cut the bone between teeth precisely at the desired angle (Fig. 3A and B). However, when deep cuts into the bone were necessary, the system was less efficient. While the cutting speed decreased temperatures rose, so pauses were necessary to let the system cool down. In these cases, the combination of Piezosurgery for the initial incision and a chisel for the final osteotomy of the bone was useful. In cases where it is necessary to obtain autologous material to fill bony defects, such as in sinus
Discussion The manufacturer claims that bone can be cut precisely without damage to soft tissue and with little bleeding (Handbook, Mectron S.r.l., Carasco, Italy, 2002). The system fulfilled these promises for us.
References 1. Sherman JA, Davies HT. Ultracision® : the harmonic scalpel and its possible uses in maxillofacial surgery. Br J Oral Maxillofac Surg 2000;38:530—2, doi: 10.1054/bjom.2000.0502. 2. Lee SJ, Park KH. Ultrasonic energy in endoscopic surgery. Yonsei Med J 1999;40:545—9. 3. Horton JE, Tarpley TM, Jacoway JR. Clinical applications of ultrasonic instrumentation in the surgical removal of bone. Oral Surg Oral Med Oral Pathol 1981;51:236—42. 4. Horton JE, Tarpley TM, Wood LD. The healing of surgical defects in alveolar bone produced with ultrasonic instrumentation, chisel, and rotary bur. Oral Surg Oral Med Oral Pathol 1975;39:536—46. 5. Vercellotti T, Russo C, Gianotti S. A new piezoelectric ridge expansion technique in the lower arch. A case report. World Dent 2001;1(2). http://www.worlddent. com/2001/05/articles/vercellotit.xml. 6. Vercellotti T, de Paoli S, Nevins M. The piezoelectric bony window osteotomy and sinus membrane elevation: introduction of a new technique for simplification of the sinus augmentation procedure. Int J Periodontics Restor Dent 2001;21:561—7. 7. Vercellotti T. Piezoelectric surgery in implantology: a case report–—a new piezoelectric ridge expansion technique. Int J Periodontics Restor Dent 2000;4:359—65.