INTRODUCTION:

Since 1950s the ultrasonic are used in many sectors, both industrial and non-industrial. Among these, its application, particularly in the field of dentistry, has revolutionized many procedures starting from scaling to the bone surgery. Most of these ultrasonic devices use the piezoelectric phenomenon where ultrasound is generated by utilizing the mechanical deformation of quartz or a piezo-ceramic disk¹. In 1950, Pohlman was the first person who introduced that the ultrasound can be applied to human tissues in the treatment of neuropathic pain and myalgias^{2, 3}. In the same year Maintz reported its positive effect on regeneration and bone healing⁴. The application of ultrasonic unit in dentistry started in 1952s initially for cavity preparations², but later on in 1980s, its application widened to the field of oral surgery involving bone. This has resulted in using piezoelectric as an alternative to traditional methods of bone surgery like (rotary, conventional) and offers various advantages².

Piezoelectricity is found in some crystals that, when subjected to mechanical charges with a help of a transducer an electrical energy can be converted into an ultrasonic vibration. A piezoelectric crystal (quartz, ceramic) is commonly used as ultrasonic transducer which converts an oscillating electric field into a mechanical vibration^{5, 6}. The philosophy behind the development of Piezoelectric Bone Surgery is based on two fundamental concepts in bone microsurgery.

(a) The first is minimally invasive surgery, which improves tissue healing and reduces discomfort for the patient. The amount of post-operative pain and swelling is always much lower than with traditional techniques.

(b) The second concept is surgical predictability, which increases treatment effectiveness. Indeed, the ease in controlling the instrument during the operation combined with reduced bleeding, the precision of the cut, and the excellent tissue healing make it possible to optimize surgical results even in the most complex anatomical cases^7-10.

Components of Piezoelectric Surgical Instrument:

The unit of piezoelectric is composed of the main body, activated with a pedal, a handle, and number of inserts with different shapes depending on the surgical need.

Main Body:

It consists of an electronic display with touchpad, a peristaltic pump, one stand for the handle and another to hold the irrigation fluid. The unit can be operated or set at different mode for specific procedures.

· Root Mode - The vibrations generated by selecting root mode are characterized by average ultrasonic power without frequency over modulation.

· Endo Mode- A limited level of power provided by applying reduced electrical tension to the transducer, which generates insert oscillation by a few microns. These mechanical micro vibrations are optimal for washing out the apical part of the root canal in endodontic surgery.

· Perio Mode - An intermediate level of power between the end program and the bone program. The ultrasonic wave is transmitted through the transducer in continuous sinusoidal manner characterized by a frequency equal to the resonance frequency of the insert used.

· Bone Mode - The vibrations generated by selecting bone mode are characterized as follows: extremely high ultrasonic power compared to root mode. Its performance is monitored by several sophisticated software and hardware controls. Frequency over modulation gives the ultrasonic mechanical vibrations its unique nature for cutting different kinds of bone.

Handle:

The cutting action is based on the generation of ultrasonic waves by piezoelectric ceramic disks inside. These handle ceramic plates are subjected to an electrical field produced by an external generator and vary their volume to generate ultrasonic vibrations. These are channeled into the amplifier, which transmits them to the sharp end of the handle. The insert is tightened with a special key for that purpose.

Inserts:

The design and features of all inserts used in Piezoelectric Bone Surgery have been conceived and developed by the Mectron Medical Technology used on specific clinical needs of each surgical technique. The inserts have been designed and organized.

Irrigation:

Piezoelectric surgery can create clear vision of the surgical area from pressurized irrigation and cavitations effect ¹.

Principles of instrumentation:

The hand piece can be fitted with different tips for osteoplasty, osteotomy, separating soft tissue from bone, and cutting bone. For example, osteoplasty for the collection of bone particles can be executed through the use of hand piece insert osteoplasty No. 1 or insert osteoplasty No. 3. When compared to oscillating micro-saws, the movement of the Piezosurgery scalpel tip is very small. The cutting is more precise and causes less discomfort for the patient. Micro movements are in the frequency range of 25 to 29 kHz and, depending on the insert, with amplitude of 60 to 210μm. This way only mineralized tissue is selectively cut. Neurovascular tissue and other soft tissue would only be cut by a frequency of above 50 kHz. A precise cut can be achieved with minimal pressure when using piezoelectric surgery in contrast to conventional micro-saws where higher degree of pressure is required. Even though increasing pressure can attribute to cutting ability it's also result in the increased heat generation ¹¹.

Biological Effects on Bone Cut by a Piezoelectric Device:

The viability of cells and structure of bone after mechanical instrumentation plays a major role in regenerative surgery. Conventional bone cutting procedure would cause damage to cell and results in necrosis of the tissues¹². Conversely, the piezoelectric surgery involves minimal pressure thus minimal heat is generated preserving the tissues. Recent study on autologous bone grafts by different methods was examined using microphotography and histomorphometric analysis which revealed the particle size, vital percentage and necrosis of the bone and also the number of osteocytes per unit of surface area. It has been concluded that the usage of bone chisel, back action, unblock harvesting, rongeur pliers and piezoelectric surgery are the best methods for harvesting vital bone. It also revealed that the bone that has been harvested with round bur on low and high speed hand piece is not suitable for grafting due to the absence of osteocytes and predominance of no. vital bone^{13, 14}.

Clinical applications in Period ontology and Implant logy:

Apart from basic procedures like scaling, root planning, piezoelectric surgery can be used specifically for procedures that require the precise removal of bone with minimal risk of injury to underlying root surfaces, and it creates a clean field with ideal bony architecture ready for flap closure. The Piezosurgery inserts used for autogenously bone harvesting produces a vibration with a width of 60 to 210μm in oscillation controlled module. The use of ultrasonic vibration makes micrometric bone cuts resulting in controlled osteotomies in mobilizing block graft in contrast to rotary burs or reciprocation saws¹⁵. It also finds it application in periodontal accelerated orthodontics where as a small vertical bone incisions were made between the teeth which allow more expedient orthodontic movement. The corticotomy performed by piezosurgical saw reduced the treatment time by 60 to 70 % with accepted degrees of pain and discomfort ¹⁶. In Alveolar ridge split procedures where it is involves razor sharp bone chisels and rotator or oscillating saws. This is time consuming and requires technical skill. Rotating saws used damage soft tissues such as tongue, cheek and the vertical incisions require more effort and care but with piezoelectric surgery, the split crest procedure used is technically less sensitive and horizontal and vertical incision is made without damaging the adjacent structures ¹⁷.

The piezosurgery device can be used for soft-tissue debridement to remove the secondary flap after incision through retained periosteum. By changing to a thin, tapered tip and altering the power setting, the piezosurgery device can be used to debride the field of residual soft tissue. In Curettage the piezo electric device can be used for debriding the epithelial lining of the pocket wall resulting in micro cauterization¹⁸. In Sinus grafting the piezoelectric device used for sinus elevation procedure comprises of hand piece fitted with the insert and irrigation fluid which removes debris from the cutting area¹⁹.

ADVANTAGES:

· Micrometric cutting action.

· Selective cutting action: minimum soft tissue damage - ultrasonic frequency used does not cut soft tissue.

· Maximum intra-operative visibility (cavitations effect).

· Minimum surgical stress - Excellent tissue healing .The cutting action is less invasive, producing less collateral tissue damage, which results in faster healing.

· Sterile water environment for better asepsis (free from contamination) ¹.

DISADVANTAGES:

· Operating time for osteotomy is long ¹⁹.

· Tissue damages can happen due to increased working pressure which disrupts the vibration it transformed into heat energy²⁰.

DISCUSSION AND CONCLUSION:

Most of the periodontal and oral surgical procedures require bone cutting. Although traditional method of bone surgery provides better predictability and ease of application, they have several drawbacks such as a high heat generation, damage to the cells, necrosis of the tissues. To overcome these factors the piezoelectric surgery has been introduced which causes micro metric and selective cutting, creates a clear cutting field and excellent tissue healing. As a result, periodontal and implant logy surgical techniques such as bone harvesting (chips and blocks), crustal bone splitting, and sinus floor elevation can be performed with greater ease and safety. The better clinical results are due to its positive effects on the first phases of bony healing; it induces an earlier increase in bone morphogenetic proteins, controls the inflammatory process better, and stimulates remodeling of bone as early as 56 days after treatment ²¹. Nerve transpositioning, sinus floor elevations, distraction ontogenesis, and a number of other sensitive procedures are easier and safer to perform with piezoelectric surgery⁷. There are few limitations like operating time for osteotomies is slightly longer than with traditional saws ¹⁹, and increasing the working pressure impedes the vibration of devices that transform the vibrational energy into heat, so tissues can be damaged²⁰.

With this scientific evidence, it is wise to conclude that the Piezosurgery is truly an innovative osseous surgical technique in field of dentistry compared to the traditional hard and soft tissue surgical methods that uses manual or rotary instruments. The handling characteristics of the technique offer advantages such as minimal risk of injury to the soft tissues, bloodless surgical field, comfort and precision to the surgeon, minimum postoperative pain, faster healing and the limitation being increased operating time and technique sensitivity.

REFERENCE:

1. Vinesh Kamath, B S Jagadish Pai, Padma, Namita Jaiswa Piezosurgery– A True Revolution in Periodontics and Implantology. Journal of Dental Herald (April 2014) Issue:2, Vol.:1

2. Escoda-Francolí J, Rodríguez-Rodríguez A, Berini-Aytés L, et al. Application of ultrasound in bone surgery: two case reports. Med Oral Patol Oral Cir Bucal 2010; 15: 902-5

3. Kennedy JE, Ter Haar GR, Cranston D. High intensity focused ultrasound: surgery of the future? Br J Radiol 2003; 76: 590-9.

4. Maintz G. Animal experiments in the study of the effect of ultrasonic waves on bone regeneration. Strahlentherapie 1950; 82: 631-8.

5. Ultrasonics. Encyclopaedia Britannica. Encyclopaedia Britannica Online. Encyclopaedia Britannica Inc., 2012. Web. 09 Sep.

6. Vercellotti T. Technological characteristics and clinical indications of piezoelectric bone surgery. Minerva Stomatologica 2004; 53: 5

7. Boyne PJ, James RA. Grafting of the maxillary sinus floor with autogenousmarroe and bone. J. Oral Surg 1980; 38: 613-616.

8. McFall TA, Yamane GM, Burnett GW. Comparison of the cutting effect on bone of an ultrasonic cutting device and rotary burs. J Oral Surg, Anesthand Hosp D Serv 1961; 19: 200-209.

9. Vercellotti T, Majzoub Z, Trisi P. Valente ML, Sabbini E, Cordioli G. Histologic evaluation of bone response to Piezoelectric, surgical saw and drill osteotomies in the rabbit calvaria. Int J oral and Maxillofac implants. (Submitted).

10. Vercellotti T. The piezoelectric bone surgery: New Paradigm. Quintessence Publisher.

11. Schlee M, Steigmann M, Bratu E, Garg AK. Piezosurgery: basics and possibilities. Implant Dent. 2006 Dec; 15(4):334-40.

12. Mauro Labanca, Flavio Azzola, Raffaele Vinci, Luigi F. Rodella. Piezoelectric surgery: Twenty years of use. British Journal of Oral and Maxillofacial Surgery 46 (2008) 265–269.

13. Chiriac G, Herten M, Schwarz F, Rothamel D, Becker J. Autogenous bone chips: influence of a new piezoelectric device (Piezosurgery) on chip morphology, cell viability and differentiation. J Clin Periodontol 2005; 32:994–9.

14. Vercellotti T, Nevins ML, Kim DM, et al. Osseus response following resective therapy with piezosurgey. Int Periodontics Restorative Dent 2005; 25:543–9.

15. Jonathan Schofield and Amit Patel – Using piezosurgery to harvest a block bone graft from symphyseal region: a clinical case presentation. Implant dentistry today 2007; 1(4): 20-24.

16. Landes C.A, Stubinge, R et al Piezoosteotomy in orthognathic surgery versus conventional saw and chisel steotomy. Oral Maxillo Fac Surg 2008; 12(3):139-147.

17. Mauro Labaca, Flavio Azzola, Raffaele Vinci, Luigi F. Rodella. Pieezoelectric surgery: Twenty years of use. British Journal of Oral and Maxillofacial Surgery 2008; 46:265-269.

18. Hema S, Kranti K, Sameer Z. Piezosurgery in periodontology and oral implantology. J Indian Soc Periodontol 2009; 13(3):155-156.

19. Vercellotti, Paoli SD, Nevins. The Piezoelectric bony window osteotomy and sinus membrane elevation .Introduction of a new technique for simplification of sinus augumentation procedure. Int J Periodont Restorative Dent 2001; 21:561-7.

20. Schlee M. Ultraschallgest utzteChirurgie-grundlagen und M oglichkeiten. Z Zahn arztlImpl 2005: 48–59.

21. Hoigne DJ, Stubinger S, Von Kaenel O, Shamdasani S, Hasenboehler P. Piezoelectic osteotomy in hand surgery: first experiences with a new technique. BMC Musculoskelet Disord2006; 7:36.

Received on 06.08.2015 Modified on 21.08.2015

Research J. Pharm. and Tech. 9(1): Jan., 2016; Page 79-82

DOI: 10.5958/0974-360X.2016.00013.5