Piezosurgery in dentistry

Abstract

Piezosurgery (piezoelectric bone surgery) is a technique of bone surgery which is gaining popularity in the field of dentistry in the recent years. This device is being used in osteotomies, periodontology and implantology, and oral surgical procedures. Piezoelectric ultrasonic vibrations are utilized to perform precise and safe osteotomies. This article discusses the equipment, biological effects on bone, and advantages and disadvantages of this technology.

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Journal of
Oral Research
and Review
Journal of Oral Research and Review . Volume 8 . Issue 1 . January-June 2016 . Pages 1-48
ISSN 2249-4987
Volume 8 | Issue 1 | January-June 2016
Official Publication of
Panineeya Mahavidyalaya Institute of Dental Sciences & Research Center
www.pmids.org

27
© 2016 Journal of Oral Research and Review | Published by Wolters Kluwer ‑ Medknow
cutting zone that must be minimized by water irrigation.
Overheating of adjacent tissue may alter or delay the healing
response. Reduced rotational speed decreases not only
frictional heat but also cutting efciency. Motorized cutting
tools also decrease tactile sensitivity. Slower rotational speed
necessitates increased manual pressure, which increases the
macrovibration of the cutting tool and further diminishes
sensitivity.[1] Microultrasonic instruments have been developed
with the aim of improving root surface debridement.[2]
Piezosurgery (PS) (Mectron Medical Technology, Carasco, Italy)
uses piezoelectric ultrasonic vibrations to perform precise and
safe osteotomies.[2] Moreover, it reduces damage to osteocytes
and permits good survival of bony cells during harvesting of
bone.[3]
Historical Background
In 1880, piezoelectric effect was discovered by Jacques
and Pierre Curie. In 1953, within the field of dentistry,
ultrasonics established itself mainly in periodontology and
endodontics when Catuna rst reported the cutting effects
of high‑frequency sound waves on the dental hard tissue.[4,5]
In 1955, Zinner rst introduced ultrasound in the periodontal
procedure as ultrasonic scalers introducing a single, bulky
universal tip which now has been replaced by a variety of
site‑specic, slimmer tips.[2] Although ultrasonic osteotomies
Introduction
Periodontitis is a chronic inammatory disease of the supporting
tissues of the teeth. This disease is associated with crestal bone
resorption which alters the morphology of the alveolar process
and also produces reverse osseous architecture at times, which
significantly hinders the removal of bacterial plaque. The
treatment is largely based on the removal of local factors and
restoration of the bony architecture. Traditionally, osseous
surgery has been performed by either manual or motor‑driven
instruments. However, both these methods have their own
advantages and disadvantages.
Manual instruments offer good control when used to remove
small amounts of bone in areas with relatively less dense
mineralization. However, they are difcult to control in
cortical bone, particularly where precise osteotomies are
essential. As a consequence, they are mostly applied for gross
cutting of larger bone segments. Motor‑driven instruments
are often used when bone is very dense. They transform
electric or pneumatic energy into mechanical cutting action
using the sharpened edge of burs or saw blades. These
instruments generate a signicant amount of heat in the
REVIEW ARTICLE
Piezosurgery in dentistry
Dhruvakumar Deepa, Gazal Jain, Tushika Bansal1
Department of Periodontology, Subharti Dental College and Hospital, Meerut, Uttar Pradesh, 1Department of Periodontology,
Uttaranchal Dental and Medical Research Institute, Dehradun, Uttarakhand, India
Piezosurgery (piezoelectric bone surgery) is a technique of bone surgery which is gaining popularity in the field of dentistry in the recent
years. This device is being used in osteotomies, periodontology and implantology, and oral surgical procedures. Piezoelectric ultrasonic
vibrations are utilized to perform precise and safe osteotomies. This article discusses the equipment, biological effects on bone, and
advantages and disadvantages of this technology.
Key words: Dentistry, implantology, osteotomies, periodontal surgery, piezosurgery, ultrasonic vibration
ABSTRACT
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DOI:
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How to cite this article: Deepa D, Jain G, Bansal T. Piezosurgery in
dentistry. J Oral Res Rev 2016;8:27-31.
This is an open access article distributed under the terms of the
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For reprints contact: reprints@medknow.com
Address for correspondence:
Dr. Dhruvakumar Deepa,
Department of Periodontology, Subharti Dental College and
Hospital, Meerut - 250 005, Uttar Pradesh, India.
E-mail: deepa_arun@rediffmail.com

Deepa, et al.: Applications of piezosurgery in dentistry
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Journal of Oral Research and Review
Vol. 8, Issue 1, | January-June 2016
were rst described more than 20 years ago by Horton and
co‑workers, this approach was not pursued for many years. In
2000, Vercellotti et al. renewed this approach for nerve and
soft tissue protecting surgery which overcame the limitations
of traditional instruments in oral bone surgery. It was rst
reported for preprosthetic surgery, alveolar crest expansion,
and sinus grafting.[2,5]
Ultrasonic osteotomy was rst used to reposition the inferior
alveolar nerve (IAN) in 2005 by Bovi, whose case report mentions
better surgical approach, lower risk of damage to the nerve, and
the reduction of mental nerve stretching through the use of a
smaller window and apico‑coronal instrument inclination to
capture the neurovascular bundle, a method that is impossible
with conventional instruments. In subsequent case series,
ultrasonic osteotomy has been described as minimally harmful
in IAN lateralization and transposition, which was referred to as
one of the major indications for this technology.[4] Stübinger et al.
not only reported excellent postoperative healing of ultrasonically
harvested canine eminence bone used for sinus lift but also
noted the need for a longer surgical time.[5] Good average graft
size and healing were also observed in a series of forty cases of
ultrasonic bone harvesting from the mandibular ramus. Cases
have been reported in which ultrasonic osteotomy has been used
successfully for impacted canine exposure, the removal of tissue
in the vicinity of the IAN, periodontal surgery, and the removal
of osseointegrated implants.[4,5]
Recently, autologous bone that had been harvested by different
methods (round bur on low and high‑speed handpiece, spiral
implant bur on low‑speed handpiece, safe scraper, Rhodes back
action chisel, rongeur pliers, gouge‑shaped bone chisel, and
piezoelectric surgery) was examined using microphotography
and histomorphometric analysis that evaluated particle size,
percentage of vital and necrotic bone, and the number of
osteocytes/unit of surface area. The results showed that the best
methods for harvesting vital bone are gouge‑shaped bone chisel,
back action, en block harvesting, rongeur pliers, and piezoelectric
surgery. Bone that has been harvested with a round bur on
low‑ and high‑speed handpieces, a spiral implant bur, or safe
scrapers, is not suitable for grafting because of the absence of
osteocytes and the predominance of nonvital bone.
Recently, Stübinger et al. showed that autologous bone from
the zygomaticomaxillary region that had been harvested with
a piezoelectric device could be used in augmentation for stable
and esthetic placements of oral implants after a 5‑month healing
period.[3,5]
Equipment
Piezoelectric devices usually consist of handpiece and foot
switch that are connected to the main power unit. This has
a holder for the handpiece and contains irrigation uids that
create an adjustable jet of 0–60 ml/min through a peristaltic
pump removing debris from the cutting area and maintains a
blood‑free operating area because of cavitation (production
of imploding bubbles) of the irrigation solution giving greater
visibility particularly in complex anatomical areas by dispersing
coolant uid as an aerosol [Figure 1].[3,4] The instantaneous
frequency is generally automatically controlled in response to the
pressure load on the tip. The parameters under the control of the
operator, apart from the pressure applied, are the pulse frequency
(when available), the rate of delivery of coolant uid, and the
applied power, which in some instruments is limited to 3–16
W and in others has a maximum of as much as 90 W. In most
instruments, power is controlled by selecting the type of bone
to be cut or the procedure to be performed. The peak‑to‑peak
amplitude of tip oscillations, typically in the range of 30–200
mm in the plane perpendicular to the shaft of the working piece
(some instruments also or exclusively oscillate along the shaft),
ensures precise microabrasive incision.[4]
The piezoelectric system is based on the fact that certain
crystalline structures such as quartz will be subject to a change
in shape when placed within an electric eld. If an alternating
voltage at an ultrasonic frequency is applied across a piezoelectric
crystal, it will result in an oscillating shape change of the crystal
at the frequency applied. The resultant vibration produces tip
movement that is primarily linear in direction and generally
allows only 2 sides of the tip to be active at any time [Figure 2].
At present, the most widely used piezoelectric material is lead
zirconate titanate.[6,7] The piezoelectric unit operates in the 25–50
kHz range and is activated by dimensional changes in crystals
housed within the handpiece, as electricity is passed over the
surface of the crystals resulting in more favorable osseous repair
and remodeling in comparison with carbide and diamond burs.
Applications in Dentistry
Piezoelectric equipment can be used for endodontic surgery
(removing root canal fillings and fractured instruments
Figure 1: Piezoelectric Equipment (Courtesy: Mectron Dental India
Pvt. Ltd.)

Deepa, et al.: Applications of piezosurgery in dentistry
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Journal of Oral Research and Review
Vol. 8, Issue 1, | January-June 2016
from root canals), periodontology and implantology (scaling
subgingival plaque, ostectomy and osteoplasty procedures to
create positive physiologic architecture of bone support of
the involved teeth, bone grafting of an infrabony periodontal
defect, implant site preparation, implant removal, crestal bone
splitting, bone osteotomy or corticotomy, harvesting bone blocks
and bone grafting, sinus lift procedure, ridge augmentation, and
ridge expansion), tooth extraction, cystectomy, maxillofacial
surgery, surgical orthodontic surgery, otological surgery,
neurosurgery, orthopedic, and hand surgery. The advantages of
the piezo‑osteotomy can also be applied to preimplantologic
surgery for augmentative purposes, for example, sinus oor
elevation carries a much lower risk of perforation or injury to
the mucous membrane since soft tissues cannot be damaged
with this method.[3,4,8] and also auto transportation of unerupted
third molars.[9]
Clinical benefits
Unlike traditional cutting instruments, PS offers the possibility
of a cut with the following characteristics:
• Micrometric, in as much as the insert, vibrates with a range
of 60–200 μm at a modulated ultrasonic frequency, which,
while cutting, maintains the bone constantly clean, thus
avoiding excessive temperatures
• Selective cutting, in as much as the vibration frequency, is
optimal for the mineralized tissues (in fact, to cut the soft
tissues, different frequencies are required)
• Safe, in as much as the reduced range of the micrometric
vibrations, offers the possibility to perform surgery with
very great precision. The cut, in fact, could be controlled
as easily as if drawing an outline. This enables osteotomy to
be performed even in close proximity to delicate structures,
such as vasculo‑nervous structures, in general, without
damaging them.[10]
Surgical control with PS is maximum as the strength required
by the surgeon to effect a cut is far less compared to that with
a drill or with oscillating saws. In fact, burs controlled by a
micromotor require greater strength, against the rotating couple
of the instrument, obtained by applying increased pressure of
the hand. As a result, surgical sensitivity is reduced, especially
when there are structures presenting different mineralization or
even more complex soft tissues, where one runs the risk of losing
control of the latter on the drill’s stem. Furthermore, oscillating
saws, with macrovibrations, require a contrast action which is
necessary to perform a cut; even though guaranteeing excellent
linearity, they do not allow control of the depth of the cutting, at
the sides or in the center, and, therefore, it is often necessary to
complete the incision with a scalpel and hammer. From a clinical
point of view, the PS system offers three different power levels:
• Low mode indicated for apical endocanal cleaning in
orthodontic surgery
• High mode useful for cleaning and smoothing the radicular
surface
• Boosted‑mode indicated in bone surgery, necessary in
performing osteotomy and osteoplasty.[11]
Ergonomics
Experience and repeating of the movements form the basis
of surgical movements and this is the principal element to be
taken into consideration when starting to use PS. In fact, in
piezoelectric surgery, the surgical handling required is completely
different from that used with the drills and oscillating saws, as
the piezoelectric cutting employs microvibrations. It thus follows
that in order to increase the capacity of cutting, pressure of
the hand should not be increased (as with bone drills or saws),
since above certain limits, an increase in pressure prevents the
microvibration of the insert; the energy not used for cutting
is thus transformed into heat which, if prolonged, can cause
damage to the tissue. Thus, in order to avoid a surgical obstacle,
it is necessary to calculate the pressure according to the speed
of the insert.[12]
Advantages
1. Piezoelectric bone surgery seems to be more efcient in the
rst phases of bony healing; it induces an earlier increase
in bone morphogenetic proteins, controls the inammatory
process better, and stimulates remodeling of bone as early
as 56 days after treatment[13]
2. It provides faster bone regeneration and healing process
3. Great control of surgical device
4. Selective cutting and minimal operative invasion
5. Reduced traumatic stress
6. Decreased postintervention pain, and
7. No risk of emphysema.[3,8]
Disadvantages
1. The main disadvantage is its slowness. Cutting very dense
bone with ultrasound can take up to 4 times longer than
with a rotary bur
2. Tip breakage can be frequent which makes it necessary to
maintain a stock of tips
3. The cost of ultrasonic osteotomy equipment is more than
mechanical osteotomes
Figure 2: Diagrammatic representation of piezoelectric effect

Deepa, et al.: Applications of piezosurgery in dentistry
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Journal of Oral Research and Review
Vol. 8, Issue 1, | January-June 2016
4. 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
5. Moreover, the technique is difcult to learn.[4]
Biological effects on bone
The effects of mechanical instruments on the structure of
bone and the viability of cells are important in regenerative
surgery. Relatively high temperatures, applied even for a short
time, are dangerous to cells and cause necrosis of tissue. There
have been studies about the effect of piezoelectric surgery on
bone and the viability of cells.[14,15] Not only is this technique
clinically effective, but also histological and histomorphometric
observation of postoperative wound healing and formation
of bone in experimental animal models has indicated that
the response of tissue is more favorable after PS than after
conventional bone‑cutting techniques with diamond or carbide
rotary instruments.
The result of a histologic comparison of the effect of a standard
ultrasonic insert to a rotary bur and a surgical chisel was published
in 1975.[16] The ultrasonic insert, like the surgical chisel, was
found to cut and not burnish bone. While the rotary bur was
observed to produce the smoothest surface of bone, the rate of
bone healing proceeded best when the bone was removed by a
surgical chisel or ultrasonic insert. In a follow‑up study, 17 of
clinical and histologic observations using ultrasonic instruments
in the surgical removal of teeth and osseous surgery, ultrasonic
inserts were found to remove bone with ease and preciseness.
There was no evidence of detrimental histologic changes.[17]
In a study by Vercellotti et al., a modulated‑frequency piezoelectric
knife was investigated as a means of performing ostectomy and
osteoplasty.[18] The rate of postoperative level of bone change
was used to compare the effectiveness of this instrument with
a standard carbide bur and a standard diamond bur and the
results indicated that PS provided a more favorable osseous
response than traditional carbide and diamond burs when
surgical ostectomy and osteoplasty procedures were performed.
Because the PS insert vibrated within a width of 60–200 mm
at a modulated ultrasonic frequency, an increase in temperature
was avoided that eliminated bone damage. Ultrasonic osteotomy
preserves the bone microstructure which facilitates bone healing
and, in turn, osseointegration, which is the key to implant
success.[19]
Research has shown that the healing process after the surgical
procedure is facilitated with the use of piezoelectric surgery and
reduces inammatory reaction when the graft is healing, which
helps in stabilizing the live bone tissue after it has been grafted.[20]
Bone block grafting performed with piezoelectric surgery is
a more precise and gentle technique compared with the same
procedure carried out with rotary instruments. Studies conducted
by Majewski 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, nally allowing the shaping and contouring of the cortical
part of the graft. Majewski 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. Another hypotheses stated by the
author includes PS tips do not generate pressure and vibrations
in the bone when it is being prepared whereas it is difcult to
perform with the rotary instruments.[21]
The piezoelectric knife is effective in removing mineralized
tissues. Studies have shown its use in ridge expansion to place
dental implants and also to perform sinus lift procedures.[11]
The advantage of this technique is the ability to cut the bony
window with simplicity and precision, thereby avoiding the risk
of perforating the membrane as a result of the shape of the bone
scalpels working with ultrasonic modulating vibrations. Further
use of piezoelectric elevators lifted the membrane without
heightened risk of perforation even in anatomically complex
situations.[11] 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. 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.[22]
Wallace et al. conducted a study in which one hundred maxillary
sinus surgeries were performed using the piezoelectric device.
Only seven cases of perforation of the sinus mucosa were
observed. None of these perforations occurred because of the
inserts of the piezoelectric unit and all of them were caused by
the subsequent elevation of the Schneiderian membrane with
hand tools. Perforations occurred due to the presence of bony
septum (four cases) and by manipulation of extremely thin
membranes (three cases).[23] 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 signicant amount of surviving osteoblasts and
osteocytes in bone blocks removed by ultrasonic surgery, besides
that the clinical outcomes sometimes cannot be seem when
compared to surgery with rotary instruments.[24] Gonzalez‑Garcia
et al. conducted a study of 17 vertical alveolar distractions in
the posterior region of the mandible, seven in the right side
and ten in the left side. The results were compared between
two approaches: Conventional technique and piezoelectric
technique. After analyzing several criteria, the authors concluded
that the use of piezoelectric osteotomy in osteogenic distraction
to increase the alveolar ridge height prior to the installation
of dental implants is easier for the surgeon and less prone
to intraoperative complications compared with conventional
osteotomy procedures.[25]

Deepa, et al.: Applications of piezosurgery in dentistry
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Journal of Oral Research and Review
Vol. 8, Issue 1, | January-June 2016
Overall, the patient’s response is signicantly improved as
compared to traditional instrumentation also piezoelectric
surgery resulting in favorable osseous repair and remodeling
which encourages the clinicians to include this method to their
armamentarium.
Conclusion
PS is a promising, highly precise, and safe bone‑cutting system
that is based on ultrasonic microvibrations which are optimally
adjusted to target only mineralized tissue and spares soft tissue,
nerves, and vessels. The precise nature of the instrument allows
exact, clean, and smooth cut geometries during surgery. If used
judiciously, this could be of great help in performing precise
bone surgeries.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conicts of interest.
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