Laser therapy has been delivering good results for more than 30 years. Therapeutic effects are seen due to its ability to stimulate cell proliferation, revascularization, cell regeneration, local microcirculation, and vascular permeability; leading to edema reduction and analgesic effects. The piezoelectric system has been used in several surgeries recently, following the trend of minimally invasive surgery. The system consists of crystals undergoing deformation when exposed to electric current, resulting in an oscillating movement with ultrasound frequency. In oral surgery it is used in orthognathic and temporomandibular joint procedures, alveolar corticotomies, tumor excision, bone grafts, third molars, and dental implants.
Key points
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In Oral and Maxillofacial surgery laser therapy can be used as an alternative to treat neural trauma and inflammatory diseases to promote wound healing and pain relief. Stimulate tissues, promoting cellular photobiomodulation, anti-inflammatory and biostimulatory properties will be revised.
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Piezosurgery application and advantages in bone surgery, third molar extraction, dental implants, orthognathic and temporomandibular joint (TMJ) surgery, bone grafts, intraoral pathology and its effects on neurosensory disturbance.
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The use of piezoeletric system as a new standard for maxillofacial osteotomies and it’s advantages to wound healing, bone preservation, edema and pain control.
Video content accompanies this article at http://www.oralmaxsurgery.theclinics.com .
Introduction
Low-level laser therapy (LLLT) was introduced in 1967 by Hungarian physician and professor Endre Mester. It was initially used for wound healing and open ulcers to stimulate tissue healing. The therapeutic effect is to stimulate tissues, promoting cellular photobiomodulation by photochemical, photoelectric, and photoenergetic reactions. In oral surgery, it has been clinically used and evaluated for third molar extractions, orthognathic procedures, , oral pathology, , bone graft, and jaw osteonecrosis.
Each type of laser has a specific wavelength of light, and each kind of tissue reacts in a different way to each wavelength because the depth of laser energy penetration depends on its absorption and dispersion in tissues. Dispersion of laser energy is inversely proportional to the wavelength of light: the shorter the wavelength, the greater its action and deeper the energy penetration. Another critical factor is energy density. Temporal factors also should be considered, including the form of light emission (continuous or pulsed), repetition rate, and pulse width. In addition, the action of lasers depends on the duration of emissions with different energy densities and size of the application area.
Low-level laser energy does not result in heat production, and is based on photochemical and photobiological effects on cells and tissues, typically operating at powers of 100 mW or less. It can produce energy in the visible spectrum, with wavelengths between 400 and 700 nm, in the ultraviolet range, at 200 to 400 nm, or in the near-infrared range, from 700 to 1500 nm
Mounting clinical and laboratory evidence supports the use of LLLT, although researchers and therapists have questioned its clinical benefits because of a lack of methodological standardization through studies and applicability issues.
Piezoelectric technology was introduced in 1880 by Jean and Marie Curie, referring to crystals that generate electric flow under mechanical pressure. Its reciprocal action was further determined, giving the piezoelectric system a cutting action. The process consists of crystals or ceramics that undergo deformation when exposed to electric current, resulting in an oscillating movement with ultrasound frequency that has the power to precisely cut bone structures without causing injury to the soft tissues.
Several types of tips (inserts) and forms of application of this technology are available. It has indications in otorhinolaryngology, neurosurgery, ophthalmology, orthopedics, and oral and maxillofacial surgery. The piezosurgery device has a low-pressure handpiece and an integrated saline coolant spray that helps keep the temperature low and maintains optimal visibility of the surgical field. The minimal pressure allows precise cutting, along with producing less noise, which keeps the patient comfortable.
In 2005, Vercellotti and colleagues microscopically examined the bone fragments obtained during piezosurgery. These fragments showed no signs of coagulative necrosis and viable cells, typically found when using low-power ultrasonic devices. , In addition, the oxygen molecules released during cutting have an antiseptic effect, and the ultrasonic vibrations stimulate cellular metabolism. Precision in the osteotomy allows bone preservation, a factor that could accelerate bone regeneration.
Clinical applications of lasers in oral and maxillofacial surgery
On the oral mucosa, hard lasers (such as CO 2 , Nd:YA, or Er:YAG) are mainly used for soft tissue incisional and excisional biopsies or vaporization, and soft lasers (LLLT) are applied for the treatment of inflammatory diseases to promote wound healing and pain relief. According to a consensus of an expert group at the joint congress of the North American Association for Photobiomodulation Therapy (NAALT-2017) and the World Association of Laser Therapy in 2014, the term photobiomodulation therapy has been suggested to replace the term LLLT and all other terms used to describe a similar low-level light treatment.
Laser radiation has been used in surgical procedures to increase benefits by improving the clinical prognosis. It has some advantages, such as disinfection of the operative field, absence of vibration, vaporization of lesions, patient comfort, anti-inflammatory and biostimulatory properties, precision in tissue destruction, minimal damage to adjacent tissues, hemostatic effect, and pain control and edema reduction. , ,
LLLT has been used to treat inflammatory and painful conditions, such as herpes labialis, burning mouth syndrome, stomatitis, oral mucositis, oral lichen planus, dentin hypersensitivity, pericoronitis, gingivitis, angular cheilitis, periodontitis, xerostomia, alveolar osteitis, temporomandibular joint dysfunction, jaw osteonecrosis, and trigeminal neuralgia, among other clinical situations. ,
In oral surgery treatment, using LLLT proved satisfactory for patients who had cellular tropism in bone tissues. Thus, LLLT enables bone repair and remodeling through its anti-inflammatory and analgesic activity. Laser therapy presents numerous advantages: it is minimally invasive, safe, and nontoxic, and it has a low risk of complications.
Despite these good results, the analgesic properties of therapeutic lasers are controversial in the current literature. Changes in parameters that can be applied in wavelengths for each specificity, the energy that will be used for a given procedure, fluency of use, power of the laser to be used, treatment time, and possible repetition remain unclear.
Oral Pathology (Oral Mucositis/Burning Mouth Syndrome/Oral Lichen Planus/Leukoplakia/Stomatitis/Jaw Osteonecrosis)
A common adverse reaction in antineoplastic treatment is oral mucositis (OM). Clinically, it is an inflammatory condition of the mucosa that presents with atrophic erythema, ulceration, and hemorrhage. Its lesions can cause pain, dysphagia, changes in oral hygiene, and malnutrition. Intraorally, it develops predominantly in areas of nonkeratinized mucosa, such as the floor of the mouth, tongue, cheek mucosa, and soft palate. OM can predispose the patient to fungal, viral, and bacterial infections, and may result in systemic infections.
The therapies involve multidisciplinary evaluation, and include oral hygiene protocols, anti-inflammatory drugs, opioid analgesic, antimicrobial agents, cryotherapy, oral rinses, cytoprotective agents, and topical anesthetics. The meta-analysis conducted by Anschau and colleagues in 2019 showed that LLLT is an effective option for OM in patients undergoing cancer therapy. LLLT presents itself as a possible path for prophylactic and therapeutic interventions by providing pain relief, comfort, inflammation control, maintenance of mucosal integrity, and better tissue repair. Preventive application is also observed to be beneficial, appearing to reduce the incidence of severe OM lesions. ,
Burning mouth syndrome (BMS) is characterized by intraoral burning sensations, without any associated medical or dental cause. It usually appears as painful, burning sensations in the oral cavity with no clinical changes. It is more common in middle-aged patients and frequent in postmenopausal women. The absence of effective treatments for management of BMS could be the multifactorial character of this entity.
The use of LLLT improves mitochondrial function, increasing the levels of serotonin, endorphins, collagen, and adenosine triphosphate. These biostimulatory and anti-inflammatory effects facilitate analgesia. The randomized clinical trial presented by de Pedro and colleagues in 2020 showed that photobiomodulation (PBM) with LLLT seems to be effective in reducing pain in patients with BMS, obtaining a positive impact on the psychological state. For this reason, LLLT must be included in the interdisciplinary management protocol.
The use of topical corticosteroids is widely accepted as the treatment of choice for oral lichen planus (OLP); however, treatment with these drugs may result in secondary candidiasis and relapse, among other complications. Considering the resistance to topical treatments, studies emphasize the use of lasers in reducing pain. Clinical trials have shown that photodynamics is successful in the treatment of OLP. A systematic review showed that laser wavelengths between 630 and 980 nm, power output of 20 to 300 mW, and duration of irradiation of 10 seconds to 15 minutes was effective in management of OLP, without any reported adverse effects. The results confirm that LLLT is effective in management of symptomatic OLP and can be used as an alternative to corticosteroids.
In oral leukoplakia and aphthous and herpetic stomatitis, photodynamic therapy shows satisfactory results. Aphthous and herpetic stomatitis is usually painful. Oral leukoplakia is usually asymptomatic. The primary outcome variables were pain relief, duration of wound healing, reduction in episode frequency, and reducing the size of lesions that have malignancy potential. ,
The action of lasers produces an antiviral effect proportional to the stimulant effect on the patient’s immunity. LLLT enhances repair of exhausted cells and improves the microcirculation deficit for therapy-resistant mucosal ulcers; deficits in arterial, venous, microcirculatory, and lymphatic circulation; metabolic and neurogenetic insufficiencies; and resistant infections. The best therapeutic response occurs at the time of the appearance of the vesicles. Laser irradiation can weaken the microorganism, alleviating the symptoms and reducing the evolution time of the disease. It can also prevent the recurrence of lesions at the same sites.
The intraoral exposed bone with no healing after 8 weeks is a potential side effect of long-term bisphosphonate (BP) use or use of other antiresorptive. The main clinical symptoms are ulceration, no-healing exposed bone, fistula, swelling, and pain. There are several strategies for the treatment of medication-related osteonecrosis of the jaw (MRONJ). LLLT is an innovative strategy that has been shown to have several positive effects, including pain relief, wound healing, and nerve regeneration, and might be helpful in treating MRONJ stage I. A meta-analysis by Momesso and colleagues showed that a minimally invasive surgical intervention with high-level (Er:YAG) laser surgery seems to be a great alternative to improve clinical conditions in MRONJ stages II and III. Surgical removal of necrotic bone is mandatory, and conservative characteristics of laser, without thermal or mechanical trauma, decreases cell death and minimizes delayed healing, and significantly improves the results obtained.
However, more studies for laser applications are necessary to recommend a specific laser type, wavelength, power output, applied energy, and the time of application. Of the high variation of laser types and laser settings used, none can be currently considered as a standard laser application for treatment of oral pathology.
Orofacial Pain and Third-Molar Surgery
The analgesic effects of lasers on chronic pain of various etiopathogeneses are produced by a broad range of actions from the peripheral receptors to the stimulus in the central nervous system. With the use of lasers, an excitatory process occurs at nerve endings, which reduces pain and provides a biostimulatory, bioregulatory, anti-inflammatory, and ultimately healing effect.
An interesting clinical trial showed the analgesia promoted by LLLT in women with myofascial pain is a result of nonspecific effects during the treatment period, although active LLLT is more effective in maintaining analgesia after treatment (30 days) for the group of women with moderate anxiety, salivary cortisol above 10 ng/mL, and without contraceptive use. Another important systematic review performed by de Pedro and colleagues in 2020 confirmed an improvement in pain sensation in patients with neuropathic orofacial pain and no adverse effects or complications.
For the most common procedure at the intraoral area, third molar extractions present different results in terms of LLLT postoperative application. The expected consequences of this procedure are pain, edema, and trismus, which cause postoperative discomfort. The LLLT application can promote interference in biochemical and molecular levels, improving clinical signs and symptoms. LLLT may possibly play an important role in alveolar repair after tooth extraction because it has pronounced effects on osteoblast cultures; influencing proliferation, differentiation, and calcification processes. It can promote faster bone repair in the periapical region, as well as less bleeding and edema, considering that it stimulates endorphin release, inhibits nociceptive signals, and reduces painful symptomatology.
There are differences considering the type of laser and wavelength (which determines its penetration and action in the tissues involved), as well as the dose applied and the power of the appliance, which determine whether the tissue will capture power emission. Pain control is stimulated because the wavelength is 637 nm to 810 nm. Most of these studies applied the LLLT between 2 and 7 days after surgery. However, Hamid noted an increased pain level with similar use of the LLLT after the third molar procedure.
Paresthesia
The most common treatments proposed for the recovery of nerve tissue are vitamin complexes, local physiotherapy, electrical stimulation, acupuncture, and microsurgery; however, recent studies have shown that laser therapy exerts effects that increase the nerve’s functional activity over time. In addition, it can positively influence tissue healing and prevent or reduce neural tissue degeneration
Brignardello-Petersen performed a systematic review to assess the effects of LLLT on pain minimization and paresthesia after orthognathic surgery. There was no difference in postoperative pain immediately after surgery, but differences were observed between 24 and 72 hours after the surgical procedure.
de Oliveira and colleagues conducted a retrospective study of 125 cases in the treatment of paresthesia. The use of LLLT with continuous beam emission in the infrared range of the spectrum (808 nm), a power of 100 mW, and a power density of 100 J/cm 2 proved effective in the recovery of sensitivity after oral surgery.
Clinical applications of piezoelectric technology in oral and maxillofacial surgery
The technology works when microcrystals and ceramics develop an electric charge flow action, expanding its polarity and making perpendicular contractions when exposed to electric current. The results of these physical phenomena are 26,000 to 38,000 oscillating micro-movements (ultrasound) with high power and precise cutting, and high efficiency. Piezosurgery aims to perform osteotomies more precisely, with minimal damage to the soft tissues and minor potential of associated bone necrosis. ,
In addition, there is a linked flood system that ensures the work and comfort during the surgical procedure, along with preventing an increase in intrabone temperature. The visibility of the operatory field is always optimum due to the “cavitation effect” (physical effect resulting from ultrasound vibration of air-water bubbles) provided by the cooling irrigation fluid, dwindling the blood influx in the cut area ( Fig. 1 ).
Some important positive aspects that must be highlighted considering the use of the piezoelectric system in oral surgeries include safety, precision, comfort to the professional and to the patient, visibility of operatory field, temperature control, and a blander postoperative period. Consequently, its use in oral surgery is extensive. , ,
Third Molar Surgery and Corticotomy
Third molar surgery is one of the most common procedures performed by oral and maxillofacial surgeons. The use of the piezoelectric technique in this surgery is controversial. The advantages of using it in third molar extractions are lower risk of postoperative pain, trismus, edema, and neurosensorial damage. It also exerts less stress on bone healing. The use of conventional high-speed devices for osteotomies and odontosections generates excessive heat in the bone tissue and delays alveolar repair. The use of piezosurgery is an alternative that causes less thermal damage to the bone tissue; however, it increases surgical time and costs more than conventional instruments.
In 2 systematic reviews, meta-analysis, and trial sequential analysis presented in 2018 by Liu and colleagues and by Cicciù and colleagues in 2020, the investigators agree that the surgical time is increased with piezosurgery. Conventional rotary instruments are faster than piezosurgery to perform an odontosection; however, biomolecular modification that causes less traumatic surgery and faster healing response. This is because the piezoelectric device selectively cuts bone and causes less damage to the soft tissues, including blood vessels and nerves. In addition, it causes less bleeding during and after surgery. Piezosurgery does not produce heat, unlike conventional rotary instruments, causing less structural cellular damage and faster osteogenesis. ,
Postoperative swelling is significantly lower in the case of piezosurgery, and neurologic complications are uncommon in both piezosurgery and conventional surgery. , According to Liu and colleagues, the patients suffered fewer postoperative complications such as pain and trismus following piezosurgery; however, Cicciù and colleagues stated that there is moderate evidence that piezosurgery reduces postoperative pain and trismus ( Figs. 2–5 , [CR] ).
