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 Table of Contents  
REVIEW ARTICLE
Year : 2017  |  Volume : 14  |  Issue : 1  |  Page : 1-6

Piezowave in periodontology and oral implantology - an overview


1 Post Graduate Student, Subharti Dental College and Hospital, Meerut, India
2 Department of Periodontology, Subharti Dental College and Hospital, Meerut, India

Date of Web Publication14-Mar-2017

Correspondence Address:
D Deepa
Subharti Dental College and Hospital, Meerut
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/1687-8574.202054

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  Abstract 

Ultrasound has been used for many years in periodontics to remove tartar, debride root surfaces, and to degranulate periodontal defects. In the last two decades, dental surgical techniques have developed rapidly. Piezosurgery is a novel surgical approach which was originally developed for the atraumatic cutting of bone by way of ultrasonic vibrations and as an alternative to the mechanical and electrical instruments that are used in conventional surgery. It is based on the basic principles of 'piezoelectricity' discovered by Pierre Curie and Jacquesin 19th century. Over the past two decades, piezoelectric devices have emerged as an innovative tool in the field of dentistry. There has been extensive research on indications of piezosurgery in the field of periodontology and implantology.

Keywords: cavitation, implants, osteotomies, piezosurgery, ultrasound


How to cite this article:
Bhatnagar MA, Deepa D. Piezowave in periodontology and oral implantology - an overview. Tanta Dent J 2017;14:1-6

How to cite this URL:
Bhatnagar MA, Deepa D. Piezowave in periodontology and oral implantology - an overview. Tanta Dent J [serial online] 2017 [cited 2017 Jun 27];14:1-6. Available from: http://www.tmj.eg.net/text.asp?2017/14/1/1/202054


  Introduction Top


Dentistry over the past few years has seen a lot of innovations. Recent advances in dentistry include latest diagnostic imaging techniques like ultrasonography, cone beam computed tomography and procedures like microsurgery, implants, lasers and nanotechnology. Ultrasonic vibrations have been used to cut tissues for last two decades [1]. These innovations have made dentistry, as one of the forerunners in medical fraternity. One such novel innovation is piezosurgery (PS) invented by Tomaso Vercellotti and developed by Mectron Medical Technology. It is a true revolution in the field of periodontology and oral implantology [2].

'Piezo' is derived from Greek word 'piezen' meaning pressure. PS works on principle of 'pressure electrification', according to which piezoelectricity is found in certain crystals like quartz, rochelle salt and ceramics. These when subjected to electric charges, acquire electric polarization, expand and contract alternately to produce ultrasonic waves, since ultrasonic waves are mechanical in nature, they can induce disorganization and fragmentation of different bodies. The ultrasonic waves allows segmentation of interfaces from solid-solid by means of distinct vibration, and solid-liquid by means of cavitation [3].

Traditionally, osseous surgery has been performed using manual and motor-driven instruments. Manual instrument though offered good control when used to remove small amounts of bones in areas of dense mineralization, however, they are difficult to control in cortical bone. Motor-driven instruments are used in dense bone. They transform the electric or pneumatic energy into mechanical cutting action using sharpened edge of burs or saw blades. However, these instruments generated sufficient amount of heat to damage adjacent tissue or delay healing response. Also, the noise and macrovibrations produced by traditional motor-driven instruments could cause fear and stress in patients when surgery is performed. PS was conceived and developed to overcome the limits of traditional bone cutting instruments and to achieve the most effective treatment with least morbidity.

PS is a novel surgical technique for bone surgery with many clinical applications in dentistry including implantology. The most compelling characteristics of PS are low surgical trauma, exceptional precision, and fast healing response. As a result, PS has the ability to increase treatment effectiveness while improving postoperative recovery and healing [4].


  Historical Background Top


It was Jean and Marie Curie (1880) who first discovered the phenomenon of piezoelectric effect that gave the basis of PS device invented by Italian oral surgeon Tomaso Vercellotti [5]. Pohlman in 1950 was the first to apply ultrasound to human tissues as the treatment of myalgias and neuropathic pain and published the first study pointing out the beneficial effects of ultrasound upon bone healing and advocated its application to bone [6]. Catuna [7] reported the cutting effects of high-frequency sound waves on dental hard tissue and was the first one to apply ultrasound in the field of dentistry, specifically for preparing dental cavities. This led to the introduction of high-speed rotary instruments [7]. Zinner [8] was first to introduce the use of ultrasonics in periodontics in 1955. The field of dental scaling has undergone revolution in last two decades, passing from the manual use of curettes to the use of sophisticated electromechanical transducers. The basic technology of these ultrasonic devices use the piezoelectric phenomenon [8]. Vercellotti [3] invented the PS device using a modulated functional working frequency of 25–30 kHz. In 1997, Vercellotti first introduced the idea to use an ultrasonic device for ablation fitted with a sharpened insert, such as a scalpel blade, to perform periradicular osteotomy to extract an ankylosed root of a maxillary canine. In 1999, to distinguish it from traditional and insufficient ultrasonic bone surgery, it was decided to be named as 'piezoelectric bone surgery' [9]. Mectron developed first generation of PS device in 2000. First study about sinus lift with PS presented in the year 2001 and in 2002, first bone block grafting procedures using PS was performed. Mectron developed second generation of the PS device in 2004 which was more powerful than the previous device. In 2005, first implant site preparation treatment was done using PS. In the year 2009, third generation PS device was introduced ([Figure 1]) [2].
Figure 1: History of piezosurgery.

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  Equipment Top


Piezoelectric device typically consist of handheld device (handpiece), foot pedal, base unit [4]. There are different-shaped inserts that correspond to different applications that can be screwed into the handpiece. The insert tips are tightened to the handpiece with the dynamometric wrench, applying a pre-defined force to obtain optimum energy transmission. High-frequency oscillations of 24 000 and 29 500 Hz, modulated with a low frequency between 10 and 60 Hz, enables efficient and controlled use. The handpiece is controlled by a foot pedal with settings that could be adjusted on the base unit. Main body has a display, an electronic touchpad, a peristaltic pump, one stand for the handle another to hold the bag containing irrigation fluid. All the parts of the unit through which the liquid passes, including the handpiece cord and the handpiece itself, are fully sterilizable. Base unit is controlled solely by means of the keyboard. The unit has a display that allows the operator to select either the Bone or Root operating modes ([Figure 2]).
Figure 2: Piezoelectric equipment (courtesy: Mectron India Pvt Ltd).

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Bone mode

It is used to cut bone with selections that are specific to bone type or density. The selection recommended is:

Quality 1 for cutting and removing small cortical bone fragments.

Quality 2 for cutting and removing cancellous or spongy bone.

Root operating mode

It is used to shape, debride, and smoothen the root surfaces.

Root operating mode consists of two different programs.

  • ENDO Program: the ultrasonic frequency is set at an ideal power level for retrocanal and intracanal debridement after root canal treatment
  • PERIO Program: the ultrasonic frequency without over modulation is set at an ideal power level for scaling, debridement, and root planing.


The insert kits: kit containing the insert tips could be used for various procedures. PS inserts are classified based on their functional and clinical characteristics.

  • Functional classification:
  • The tips have been classified as sharp, smoothening and blunt tips. Sharp insert tips are used in osteotomy and osteoplasty, whenever a fine and well defined cut in the bone structure concerned is required. They are made of nitride, titanium and are gold in color. Smoothening insert tips have diamond-coated surfaces enabling precise and controlled work on the bone structures. Smoothening insert tips are used in osteotomy when it is necessary to prepare difficult and delicate structures, for example those for preparing a sinus window or for access to a nerve. Blunt insert tips are steel colored tips having rounded ends and are used to refine the cut in contact with the soft tissue. In periodontology, these insert tips are used for root planing. Gold tips are used to treat bone whereas the steel tips are used to treat soft tissues or delicate surfaces such as the roots of teeth. The golden color of the insert tip is obtained by the titanium nitride coating to improve the surface hardness, which means that their working life may be long
  • Clinical classification sorts the inserts according to basic surgical techniques of osteotomy, osteoplasty and extraction ([Figure 3])
  • OT: the identification code for inserts used to perform osteotomy
  • OP: the identification code for inserts used to perform osteoplasty
  • EX: the identification code for inserts used to perform extraction
  • IM: the identification code for inserts used to perform implant site preparations.
Figure 3: Piezo insert tips: periopiezo tips and osteotomy tips (courtesy: Clinical periodontology, 11th ed. [4].

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  Mechanism of Action Top


PS is based on the piezoelectric effect, first described by Jean and Marie Curie in 1880. PS works on the principle of 'pressure electrification', according to which when electric tension is applied across certain materials, the material expands and contracts, thus producing ultrasonic vibrations. Materials used were quartz, Rochelle salt and ceramics. When these crystals were subjected to an electric charge, they expanded and contracted alternately to produce ultrasonic waves. They concluded that ultrasonic waves could allow segmentation of interfaces from solid to solid by means of distinct vibration, and solid-liquid by means of cavitation. The vibrations thus obtained are amplified and transferred onto the insert of a drill which, when rapidly applied, with slight pressure, upon the bony tissue, results, in the presence of irrigation with physiological solution, in the cavitation phenomenon, with a mechanical cutting effect, exclusively on mineralized tissues. At present the most widely used piezoelectric material is lead zirconate titanate ([Figure 4]) [10].
Figure 4: Piezoelectric effect – direct and reverse piezoelectric effect (courtesy: Honda Electronics Co. Ltd).

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Several modes are available:

  • Low mode is useful for apical root canal treatment in dentistry
  • High mode is useful for cleaning and smoothening bone borders
  • Boosted mode is most often used in oral and maxillofacial surgery for osteoplasty and osteotomy procedures.


In this device, the electrical field is located in the handle of the saw. Due to the deformation caused by the electrical current, a cutting – hammering movement is produced at the tip of the instrument. These micromovements are in the frequency range of 25–29 kHz and, depending on the insert, with amplitude of 60–210 μm. This way only mineralized tissue is selectively cut. Neurovascular tissue and other soft tissues would only be cut by frequency of above 50 kHz [3].

Properties of piezoelectric device

  • Micrometric cutting – Due to limited vibration amplitude (max. 200 μm) and the design of osteotome tips for specific surgical situation, it offers precise bone cutting accompanied by high tactile sensitivity [11]
  • Selective cutting – Bone cutting without the risk of damaging adjacent soft tissues. The ultrasonic frequencies (25–29 kHz) that are used for hard and soft tissues are cut at different frequencies [12]
  • Bleeding free surgical site for maximum intraoperative visibility and high predictability. Due to the cavitation effect, bubbles are created from the physiological salt solution that leads to implosion and generate the shock wave causing microcoagulation [13].


Clinical applications

In the field of periodontology, apart from routine scaling and root planing, PS finds its use in crown lengthening, osteotomy and osteoplasty procedures. It is used to develop positive architecture of bone support of involved tooth. It can also be used for soft tissue debridement during flap surgeries, pocket elimination surgeries, bone grafting of an intrabony periodontal defect. Autogenous bone grafts can be easily harvested from adjacent sites with minimal trauma. PS has been successfully used in implant site preparation, alveolar ridge splitting and expansion, re-contouring of alveolar crest, bone harvesting, mental nerve reposition, maxillary sinus lift, extraction for immediate implant positioning. Sinus elevation with traditional burs is often associated with membrane perforation, surgical trauma. In such cases, piezosurgical insert with blunt tip is useful in atraumatic elevation of membrane followed by grafting procedures. It has a wide role in oral and maxillofacial surgeries ranging from atraumatic third molar extraction, enucleation of cyst and tumors, bone harvesting to alveolar distraction ostogenesis. It has also been used for hemisection, root amputation, apical resection and root canal treatment in endodontics.

Biological effects on bone and osseous response to piezosurgery

The effects of mechanical instrumentation on the structure of bone and the viability of cells are important in any type of osseous surgery. Bone necrosis may result due to any alteration in temperature [14]. Eriksson et al. [15] stated that local bone necrosis occurs in cases where temperature increases beyond 47°C for 1 min due to contact with rotary instruments. Various studies have been conducted to study the effect of PS on bone and viability of cells [16]. The histological and histomorphometric observation of postoperative wound healing and formation of bone in experimental animal models has suggested that the response of tissue is more favorable after PS than after conventional bone-cutting techniques with diamond or carbide rotary instruments. The best methods for harvesting bone include the back action chisels, rongeur pliers and PS. The bone surface that was cut using PS device showed no signs of lesions to the mineralized tissues and presented live osteocytes with no signs of cellular damage. On the other hand the bone that was harvested using burs showed absence of osteocytes and predominance nonvital bone [17],[18]. Expression of heat shock protein 70 as a potential biomarker of immediate postoperative stress in patients undergoing two different surgical procedures of different severity was examined in a study. Expression of heat shock protein 70 both at mRNA and at protein level in the conventional group was twofold higher than in the PS group. The results of the study suggested that tooth movement by the PS method causes relatively low stress in the alveolar bone. It provides low stress to patients and this might help in cell repair after the surgical procedure [19].

In a study by Sohn et al. [11] the efficacy and safety of piezoelectric surgery during intraoral harvesting of bone blocks was described. A piezoelectric osteoplastic scalpel was used to remove the sharp alveolar crest visible on exposing the anterior mandible and widen the narrow ridge. It was confirmed that the Piezosurgery System (Mectron) created an effective osteotomy with minimal or no trauma to soft tissue, in contrast to conventional surgical burs or saws. In addition, piezoelectric surgery produced less vibration and noise because it uses microvibration, in contrast to the macrovibration and extreme noise that occurred with a surgical saw or bur. Microvibration and reduced noise minimize a patient's psychologic stress and fear during osteotomy under local anesthesia.

The crown lengthening technique performed with PS using appropriate inserts makes it possible to effectively reduce bone while preserving root surface integrity [4]. The rate of postoperative wound healing (baseline and 14, 28, and 56 days after surgery) in a dog model following surgical ostectomy and osteoplasty was used as a marker compare the efficacy of the PS instrument with a commonly used carbide bur or a diamond bur. The osseous repair and remodelling following periodontal respective therapy with piezoelectric approach was found to be more favorable than harvesting with carbide or diamond burs [14]. Studies conducted by Majewski [20] have shown that, with the use of piezoelectric surgery, it was possible to more accurately harvest the correct shape of block for a ridge defect and to stabilize it in the recipient site, finally allowing the shaping and contouring of the cortical part of the graft. He also observed that piezoelectric surgery was used to delicately shape and thin a layer of cortical block that could serve as an element supporting the shape of the reconstructed alveolar process. The evaluation of ultrasonic bone surgery or PS, in split-crest procedures with immediate implant placement demonstrated an overall success rate of 97.2%, with no risk of thermonecrosis, minimum risk of soft tissue alteration and satisfactory bone cutting efficiency [20].

Piezosurgical site preparation provides similar primary stability and short-term survival rate of an implant when compared with conventional site preparation techniques. Stelzle et al. [21] emphasized that the applied load on the handpiece may increase the preparation speed but it may also increase the negative thermal effect on the bone. PS is suitable to collect the bone particles with optimal size and low heat generation, thereby minimizing the possibility of thermal necrosis. A feature of the use of PS is the significant amount of surviving osteoblasts and osteocytes in bone blocks removed by ultrasonic surgery, when compared with surgery with rotary instruments [22].

In a study by Romeo et al. [23], four devices – Er: YAG laser (2.94 mm), PS, high-speed drill and low-speed drill were compared for the peripheral bone damage induced by them. Four different parameters were analyzed: cut precision, depth of incision, peripheral carbonization and presence of bone fragments. Er: YAG sections showed poor peripheral carbonization. The edges of the incisions were always well-shaped and regular, no melting was observed. The PS specimens had superficial incisions without thermal damage but with irregular edges. The sections obtained by traditional drilling showed poor peripheral carbonization especially if obtained at a lower speed [23].

The quantitative roughness analysis of osteotomized bone surfaces prepared by conventional osteotomy and piezoelectric technique was explored. It was concluded that the ultrasonic technique preserved the original bone structure and the superficial roughness was minimum for the piezo-osteotomy surface followed by the microsaw and Lindemann bur osteotomy surfaces [24]. PS therefore has a potential role in osseous surgery.

Advantages

  • Piezoelectric bone surgery seems to be more efficient in the first phases of bony healing; it induces an earlier increase in bone morphogenetic proteins, controls the inflammatory process better, and stimulates remodelling of bone as early as 56 days after treatment [25]
  • It provides faster bone regeneration and healing process
  • Greater control of surgical device
  • Selective cutting and minimal operative invasion
  • Reduced traumatic stress
  • Decreased post-intervention pain
  • No risk of emphysema [26].


Disadvantages

  • Increased operating time required for bone preparation
  • Increased cost of the PS equipment as compared with the motor-driven or manual instruments
  • Longer operating time and increasing the working pressure impedes the vibration of device that transforms the vibrational energy into heat, so tissues can be damaged, therefore, the use of irrigation is essential not only for the effect of cavitation but also to avoid overheating
  • Moreover, the technique is difficult to learn [26].


Contraindications

There are no absolute contraindications, but it is contraindicated in cases where either the patient or operator has an electrical pacemaker. Also, age factor is a relative contraindication for any surgery [5].

Cost of piezosurgery equipment

Mectron PS equipment – Rs. 613 849.

PS unit (8002) (Dental USA) – Rs. 408 550.65.

Dental Woodpecker Ultraschall Piezo motor handpiece – Rs. 184 291.13.


  Conclusion Top


PS appears to be an advanced and conservative tool when compared with existent traditional methods for the treatment of bone and soft tissues. It has the ability to increase treatment effectiveness while improving postoperative recovery and healing although its performance regarding postoperative bone regeneration is still unclear and will require further evaluation. Inspite of the fact that a great deal of scientific research focuses on new products for tissue engineering and bone regeneration, the importance of minimal surgical trauma for optional bone healing and regeneration should not be overlooked. The effectiveness of PS has the potential to redefine the concept of minimally invasive surgery in bone regeneration procedures and implantology.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
  References Top

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Vercellotti T, Paoli SD, Nevins M. The piezoelectric bony window osteotomy and sinus membrane elevation: introduction of a new technique for simplification of sinus augmentation procedure. Int J Periodontics Restorative Dent 2001; 21:561–567.  Back to cited text no. 3
    
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