Photo ©John Lewis
Ultrasonic piezoelectric surgery units have become a popular tool among veterinary dentists. Although this technology is relatively new to our industry, the use of ultrasonic surgery in dentistry was first documented in 1953.1
Uses for piezoelectric technology
Recent advances in ultrasonic piezoelectric technology have allowed for clinical improvements in cutting and shaping bone. Specifically, the passage of electric current across ceramic crystals modifies them, causing oscillation. Voltage applied to a polarized piezoceramic causes it to expand in the direction of and contract perpendicular to polarity. A frequency of 28 to 36 kHz is used because the movements created at this frequency (ranging between 60 to 210 µm) cut only mineralized tissue; neurovascular tissue and other soft tissues are cut at frequencies higher than 50 kHz.2 Think of the piezoelectric surgery unit as a miniature cast-cutting saw, where the blade works by oscillation rather than rotation. Benefits of piezoelectric surgery include:
- minimal mechanical and thermal damage to soft tissue structures;
- sterile irrigant delivered to the surgery site;
- very fine control for precise bone-cutting;
- cavitation of irrigation solutions, providing an antimicrobial effect;
- inducing an earlier increase in bone morphogenetic proteins;
- controlling the inflammatory process better; and
- stimulating remodeling of bone.3
In my hands, operating times for osteotomies tend to be longer when using piezosurgical units than with traditional saws and high-speed burs. The piezosurgery unit is not a replacement for your high-speed dental drill, but rather an adjunctive tool to allow for more precise bone dissection when finesse is important. In the past month, I have used the piezosurgery unit for extraction of firmly rooted mandibular canine teeth, mandibulectomies, maxillectomies, and treatment of open-mouth jaw locking with zygomectomy and coronoidectomy. In my experience, the best applications are those surgeries requiring bone removal in areas of important soft tissue structures, such as neurovascular bundles.
Also known as a "rim excision," a marginal mandibulectomy describes removal of the dorsal border of the mandible for treatment of tumors requiring less radical margins, where the ventral portion of the mandible can remain intact and clean margins can still be achieved around the site. Usually, the most common clinical use for this surgery is when an acanthomatous ameloblastoma occurs in the area of the mandibular first molar tooth of a large dog.4 Since the ventral-most portion of the bone cut for this surgery is often directly over the neurovascular bundle of the mandible, piezosurgery is a great option when cutting bone. However, since there are more efficient ways to cut through tooth crowns and through the outer layers of bone, my rim excisions involve initial use of a bur on a high-speed air-driven or electric handpiece, followed by use of the piezosurgery unit when approaching the neurovascular bundle.
Challenging extractions
Another use for piezosurgery is as a periotome to minimize trauma and alveolar bone loss during a tooth extraction.5,6 Using thin tips that can find the periodontal ligament space, ultrasonic vibrations help to detach the attachments of the tooth. Particularly important in humans receiving a dental implant in the area of an extracted tooth, piezosurgery allows for minimal loss of alveolar bone height and may improve postoperative outcomes. I particularly like to use the piezosurgery unit for extractions when a patient's tooth is proving to be challenging to extract, such as a mandibular canine tooth and in extraction of teeth that are unerupted.
Certain piezosurgical tips have saw-like teeth that oscillate to cut through thick bone of the palatine process of the maxilla during oncologic surgery that requires maxillectomy. The piezosurgery unit shines here compared to a high-speed handpiece due to the fact soft tissues adjacent to the tip do not need to be retracted/dissected away from the line of bone like they would when using a high-speed dental bur. Precise cuts can be made to follow a planned arc for obtaining clean margins around a tumor.
Surgery of the zygomatic arch, coronoid process, and temporomandibular joint (TMJ) can be easier and less risky with the use of a piezosurgery unit. One of the most common reasons for the need to remove the condylar process is when ankylosis of the TMJ joint occurs, or pseudoankylosis due to callus formation of surrounding bony structures. This condition occurs most commonly in young cats that have had a history of trauma to the caudal mandibular structures.7 The clinical presentation involves the patient's inability to open their mouth. Relieving this condition can be accomplished by use of a combination of rongeurs, burs, and piezosurgical tips to remove the ankylotic mass of bone. A prospective study in humans found ultrasonic versus conventional gap arthroplasty resulted in significantly less blood loss, while gains in extent of maximal mouth opening were substantial and stable in both groups.8
John Lewis, VMD, FAVD, DAVDC, practices dentistry and oral surgery at Veterinary Dentistry Specialists and is the founder of Silo Academy Education Center, both located in Chadds Ford, Pa.
References
1 Catuna MC. Sonic surgery. Ann Dent 1953;12:100.
2 Labanca M, Azzola F, Vinci R, Rodella LF. Piezoelectric surgery: twenty years of use. Br J Oral Maxillofac Surg 2008;46:265-269.
3 Preti G, Martinasso G, Peirone B, et al. Cytokines and growth factors involved in the osseointegration of oral titanium implants positioned using piezoelectric bone surgery versus a drill technique:
a pilot study in minipigs. J Periodontol 2007;78:716–722.
4 Walker KS, Reiter AM, Lewis JR. Marginal mandibulectomy in the dog.
J Vet Dent. 2009;26(3):194–198.
8 Jia, T., Wang, L., Chen, Y. et al. Ultrasonic versus conventional gap arthroplasty for the release of ankylosis of temporomandibular joint: a prospective cohort study. Sci Rep 9, 385 (2019) doi:10.1038/s41598-018-36955-3.
