Laser and Cryosurgery in Oral and Maxillofacial Surgery PDF

‫ علي الحسیني‬.‫د‬.‫م‬.‫ا‬ Laser and Cryosurgery in oral and maxillofacial surgery In conventional surgery the scalpel is used to cut or excise tissue during surgical procedures. The scalpel, however, has limitations as a surgical tool. When an area of tissue...

‫ علي الحسیني‬.‫د‬.‫م‬.‫ا‬ Laser and Cryosurgery in oral and maxillofacial surgery In conventional surgery the scalpel is used to cut or excise tissue during surgical procedures. The scalpel, however, has limitations as a surgical tool. When an area of tissue is excised hemorrhage may be difficult to control and a flap or graft may be needed to cover the defect to prevent infection and scarring. Benign and hyperplastic lesions are mostly treated by conventional surgical excision of the lesion; however, there are other modalities for the treatment of such lesions by laser or cryosurgery. Laser Laser is an acronym derived from ’Light Amplification by Stimulated Emission of Radiation'. Lasers have been used in surgery since more than five decades and becoming standard equipment in most major hospitals around the world, and many surgical procedures now indicate their preferred use. Different types of lasers are used in many branches of surgery and medicine. The properties of laser light depend on wavelength which is measured by nanometer (nm). It emits light within or beyond the visible wavelengths, and its power may vary from a milliwatt to megawatts. Ordinary light waves from a normal source not produce a powerful cutting beam because they emerge randomly at various wavelengths, while laser light is “coherent”; this means that the waves are in the same phase, “monochromatic” all have the same wavelength (color), and “unidirectional” all waves are parallel with a very small divergence. So that none of the energy from the laser light source is lost by interference. Compare a 60 W ordinary light bulb producing light and heat with a 60 W laser beam that would cut metals. Output may be in a continuous wave or pulsed. Pulse waves are with duration of 0.1 second or less. Q-switched lasers produce pulses of less than 1 μs, which deliver very high energy without generating excessive heat. Laser effects on tissue may be: Photothermal, Photoablative, Photomechanical or Photochemical therapy. There are different types of lasers and each type has a specific biological effect. For that reason, it is imperative for the clinician to select the laser type according to the requisite. Classification of laser according to power: There are two types of lasers according to the power: 1. Low-energy laser: ❖ Argon laser produces visible light; it is passes through water but is absorbed by pigment such as melanin or hemoglobin so mainly used for treatment of vascular lesions. ❖ Helium-neon laser produces visible light which used as aiming beams, pointers, caries detector and stimulation of wound healing. ❖ Diode laser; the active medium of the diode laser is a solid-state semiconductor made of aluminum, gallium, arsenide, and occasionally indium. All diode wavelengths are primarily absorbed primarily by tissue pigment (melanin) and hemoglobin. These are poorly absorbed by the hydroxyapatite and water. Diode laser as Gallium-Arsenide laser (average power of 5 mW) has a biostimulation effect by stimulating cell growth of the epithelium, connective tissue, bone and stimulate regeneration of nerve cells. Furthermore, it has anti-inflammatory effect, pain alleviation. Biolase laser active medium is semi-conductor diode utilized for TMJ pain relief and teeth whitening. 2. High–energy laser: ❖ Dual diode laser 10 W (5 W, 810 nm coagulation and 5 W, 980 nm ablation) used for the treatment of aphthous ulcer, denture sore, flap incision, and gingivectomy. ❖ Nd: YAG laser wavelength is highly absorbed by the pigmented tissue, making it a very effective surgical laser for cutting and coagulating soft tissues. ❖ Erbium wavelengths have high affinity for hydroxyapatite and water. It is the laser of choice for treatment of dental hard tissues (cavity preparation, apicoectomy) and can also be used for soft tissue ablation. ❖ Waterlase laser (the active medium Erbium, Chromium: Yttrium Scandium Gallium Garnet (Er,Cr:YSGG), 2780 nm used for tooth cavity preparation, gingivectomy, frenectomy, biopsy, and treatment of peri-implantitis with minimum amount and in some cases without anesthesia. In addition, it has a biostimulation effect which promote wound healing and hemostasis. ❖ CO2 laser wavelength has a very high affinity for water, has the ideal properties for soft tissue treatment, resulting in rapid soft tissue removal and hemostasis on contact. It has a very shallow depth of penetration. Cell structure is destroyed by expansion as water boils, denaturation of protein also occurs but with a very narrow layer of tissue damage below the treated area and better healing, so it is used for cutting, coagulating, cauterizing and destructive effect; that if the high energy laser is focused, the laser can be used  as a bloodless scalpel, and when the beam is defocused the laser will vaporize soft tissue, which is surrounded by a thin layer of heat coagulated tissue in which blood vessels and lymphatic channels are sealed. Carbonization during treatment leaves black particles on the surface. The CO2 laser used mainly for biopsy, surgical excision of benign and premalignant lesions, gingivectomy, frenectomy, flap incision, implant exposure and preprosthetic surgery with minimal bleeding, scarring and postoperative complications. The specific tissue cut and the ability to support the healing process, makes laser really different from an electrosurgical scalpel (cautery). Electrosurgery damages minimum 200-400 cells layers, while a Diode maximum 2 to 5 cell layer, thus allowing a faster healing. Laser can target in a very specific way depending on its wavelength (water and hydroxyapatite for Er:YAG, on the other hand, dark pigments as melanin and hemoglobin for Nd:YAG laser). In contrast, electrosurgery is absolutely nonspecific. Er:YAG, CO2 and Diode lasers used for treatment of peri-implantitis by complete elimination of bacteria loaded titanium dental implant and these lasers do not disturb titanium surface. However, bone graft along with implant decontamination treatment may be more favorable for the treatment of peri-implantitis than nonsurgical decontamination procedure alone. Table: Therapeutic lasers (Types, wavelength & uses): Type and mode Wavelength and color Uses Excimer (pulsed) 190 nm-351nm UV Dentine hypersensitivity Argon (continuous) 488 nm blue - 515 nm green Vascular lesions (port-wine naevus), composite curing. KTP (potassium- 532 nm green Telangiectasia, tonsillectomy, tattoo titanyl phosphate), removal. (pulsed) Tunable dye laser 504 nm green - 632 nm red Vascular lesion, tattoo removal, dentine (cont. or pulsed) hypersensitivity. Helium-neon 633 nm red Guiding beams and pointers, caries (cont.) diagnosis, stimulation of wound healing. Diode laser (pulsed 650 nm - 950 nm IR stimulate the healing process and reduce or cont.) postoperative complications, treatment of aphthous and herpetic stomatitis, and teeth whitening. Dual diode (pulsed 810 nm and 980 nm IR gingivectomy, excision of hypertrophic or cont.) tissue, frenectomy.  Nd: YAG (cont., 1060 nm IR gingivectomy, peri-implantitis, excision of pulsed or Q- hypertrophic tissue. switched) Er: YAG (pulsed) 2940 nm IR Caries removal, cutting of enamel, dentine & bone. Carbon dioxide 10600 nm IR Tumor excision, coagulation of small (cont., pulsed or vessels, gingivectomy, implant exposure, Q-switched) denture induced hyperplasia, cutting of enamel, dentine & bone. The advantages of laser using: 1. Excision of wide area with minimum scarring. 2. Reduce bleeding during surgical operation. 3. Moderate pain and swelling postoperatively. 4. Reduce healing time. 5. Bacterial decontamination of the periodontal pocket and in peri-implantitis. 6. No potentiating of malignant changes. 7. No need for mucosal or skin graft. Hazards and precautions required when using laser: When laser is performed in oral and maxillofacial surgery some precautions must be taken: 1. Under general anesthesia special measures are carried out to protect the endotracheal tube as well as the adjacent and peripheral tissues such as teeth and lips from damage, so wet towels must be placed over them. Anesthetic tube may be pierced, resulting in ignition of anesthetic gases within the lungs, which is fatal. 2. Laser protective eye glasses must be worn by all persons in the operating room which is specific for the used laser wavelength, and use non-reflective instruments (achieved by sand blasting). The laser beam is destructive on direct exposure and by the reflection of laser from shiny metal objects into the operator’s eyes, will cause severe thermal damage to the cornea, lens and retina. 3. The potential effects of plume or surgical smoke produced by high energy laser. Toxic chemicals are produced when tissue is burned also blood aerosols and viruses such as human papilloma virus in the laser plume is thought to be capable of transmitting disease. A face mask alone does not provide adequate protection, and smoke evacuation (vacuum) is recommended. 4. Training and certification of users. 5. Restricted access to laser area, warning lights and notices. Cryosurgery The physical effect of cryosurgery offers alternative method of removing or devitalizing tissue. Cryosurgery mechanism relies on the fact that rapid freezing and thawing of tissues causing cell death and necrosis. Cryosurgery makes ice crystals in and around cells; causing disruption of cell membranes and contents. Blood flow to the area is reduced so that a larger and colder ice ball is achieved at the next application. Vascular damage also results in ischemic necrosis. The technique of freezing selected areas in the oral cavity is accomplished by a cryoprobe tip contacting lesion tissue after refrigerant liquid has entered the tip in controlled amount. The temperature of the contacted tissues is lowered to around –150 °C by liquid Nitrogen, so cell injury and subsequent necrosis occur as a result of this brief contact. Recently cryosurgery machine uses liquefied Argon gas, this gas creates ice ball at the tip of the cryoprobe and freeze the lesion tissue at temperature of – 40 °C. Furthermore, Nitrous oxide units are commonly available in hospitals and are suitable for most oral applications. The temperature of the refrigerant liquid is determined by the boiling point. Cryoprobe tips come in a variety of shapes and sizes. Flat or dome-shaped tips from 3-10 mm are useful in the mouth. Long, narrow and insulated probes are available for freezing nerves. Cryosurgery technique: Under local anesthesia the probe is applied to the lesion and switched on. The probe is held firmly onto the lesion until an ice-ball forms and freezing is continued. The time of application will usually be about 1 minute. The probe should not pull away because it will be adherent to the lesion. For vascular lesions, the effect is enhanced by compressing the lesion with the probe, which decreases blood flow. On turning the machine off there should be a rapid thaw and the probe is released. One or two further applications are made after 1 minute to allow a complete damage to the lesion. Protocols suggested that for most benign mucosal lesions a 1–2 minutes freeze/thaw cycle using a cryoprobe is sufficient. Premalignant lesions are recommended to undergo three applications for 2-minute freeze/thaw cycles. For smaller lesions shorter freeze/thaw cycles (20–30 seconds) are adequate. Experience is necessary to judge the amount of treatment and the extent of the freeze. Uses of cryosurgery: 1. Ablation of surface lesions such as viral warts and small benign tumors. 2. To destroy fungating masses so improve patient comfort because of little postoperative created defect.  3. Treatment of hemangiomas. The large lesion should be treated by multiple sessions, while small lesion within the oral cavity can be treated by one or two freeze/thaw cycles on one session. Capillary haemangioma of the skin are best treated by multiple short (10 seconds) freezes at fortnightly intervals so as to avoid scarring. 4. Cryosurgery also used for the treatment of trigeminal neuralgia because nerve can be blocked without causing the secondary neuralgia that often follows nerve section, avulsion, or alcohol blocks. Pain relief lasts for several months, although there is a recurrence but the return of sensation before recurrence of the pain is said to be an advantage to avoid irreversible nerve damage. Repeated applications to the affected nerve mainly by intra oral approach may need for the treatment of neuralgia. 5. Treatment of bone cavity after curettage of odontogenic keratocyst or central giant cell granuloma to reduce recurrence. A water-soluble gel may be used to aid contact liquid nitrogen with the bone surface to provide adequate effect. A liquid nitrogen spray would be preferable because it produces a much faster and deeper freeze. Care must be taken to protect mucosal flap and adjacent soft tissue, especially with liquid nitrogen gas. Refrigerant properties of liquid cryoprobe systems Type Boiling point Surface temperature Liquid nitrogen -196 °C -150 °C Nitrous oxide -89 °C -75 °C Carbon dioxide -78 °C -50 °C Liquid nitrogen spray -196 °C -196 °C The advantages of using cryosurgery: 1. Used for medically compromised patient with advanced neoplastic fungating mass. 2. Minimal blood loss 3. Minimum postoperative pain 4. Maintain bone structure 5. Good recovery of nerve function 6. Excellent for hemangiomas The disadvantages and complications of using cryosurgery: 1. Recurrence of the lesion because difficult in assessing extent of tissue destruction. 2. Damage to nearby healthy tissue especially nervous tissue led to alteration of sensation. 3. Significant postoperative edema (airway embarrassment). 4. Not used to cut tissues. 5. The whole lesion not available for histopathological study. 6. Dysplastic changes can be potentiated. Tumor growth may be accelerated after cryotherapy, so malignant and premalignant lesions are therefore better treated by other methods. 7. Hypertrophic scarring. 8. Hypo or hyperpigmentation.  Oral and Maxillofacial Surgery/Fifth year ‫ سلوان يوسف‬.‫د‬.‫أ‬ Vascular Anomalies Vascular anomalies include various diseases, which are classified into two distinct entities according to the International Society for the Study of Vascular Anomalies (ISSVA) classification:  Vascular tumors (hemangioma) with proliferation of vascular endothelial cells.  Vascular malformations characterized by the abnormal dilation of vessels without proliferation. History and clinical examination In most cases, an accurate history and physical examination will help establish the diagnosis. In cases in which the diagnosis is equivocal a repeat assessment in 3–4 months will greatly improve the chance of arriving at a diagnosis and special investigations are only occasionally necessary. Investigations Further investigations are considered only if the diagnosis is in doubt or the investigation will influence the decision and method of treatment. No single investigation is appropriate for all lesions. Imaging is used to:  Confirm the suspected diagnosis.  Establish the extent of the lesion.  Document any associated abnormalities. Magnetic resonance imaging (MRI) is the investigation of choice, it has the following advantages:  It provides accurate information about the extent of the lesion.  It provides better contrast between the lesion and surrounding tissues.  It has multiplanar capabilities. Page | 1  It can also help distinguish between the different types of vascular anomalies. Contrast-enhanced computed tomography (CT) has a role in evaluating intraosseous lesions and the bony margins of extensive lesions that are under consideration for resection. Grey-scale ultrasound and Doppler analysis are useful in defining whether the lesion is solid or cystic and to establish the presence or absence of high flow vessels. Angiography, particularly digital subtraction angiography (DSA), has a specific but limited role in the diagnosis of vascular lesions, but should not be used as a first line investigation. It is useful for mapping out the blood supply of the lesion and in the assessment of the characteristics of flow of arteriovenous malformations. Angiography is usually reserved for therapeutic endovascular interventions. Direct intralesional injection of contrast medium may have a role in the analysis of venous malformations. Preoperative histological confirmation is seldom necessary, but features are characteristic and help differentiate between the various types of vascular lesion. Hemangioma It is the most common tumor in childhood affecting about 10% of neonates. The head and neck region is the most commonly involved site (60%). Most lesions are solitary (80%) and girls are more affected than boys (3:1). Hemangiomas can be divided into two main groups:  Infantile hemangioma which appears soon after birth.  Congenital hemangioma which is present at birth, these are further subdivided into:  Rapidly involuting congenital hemangioma. Page | 2   Non-involuting congenital hemangioma.  Partially involuting congenital hemangioma. Hemangiomas can also be described according to the depth of the lesion as:  Superficial hemangiomas originate from the papillary dermis and present as bright red macular or papular masses.  Deep hemangiomas originate from the reticular dermis or subcutaneous tissues and appear as bluish or relatively colorless masses.  Compound hemangiomas have superficial and deep components. Hemangioma runs in stages: 1. Proliferative stage: lasts about 6-10 months after which the tumor slows in growth and enters the second stage. 2. Involutive stage: the lesion becomes dull purple and less firm, 50% of the lesions show complete resolution by the age of 5 years and 90% of the cases by the age of 9 years. 3. Involuted stage: 40% of patients will have permanent changes such as; atrophy, scarring, fibrofatty tissue or telangiectasia. Complications Occur in 20% of the patients:  Ulceration with or without secondary infection.  Bleeding.  Periocular lesions may result in amblyopia, strabismus or astigmatism.  Airway obstruction in laryngeal lesions.  Visceral involvement.  Kasabach-Merritt syndrome characterized by the combination of rapidly growing hemangioma, thrombocytopenia, microangiopathic hemolytic anemia and consumptive coagulopathy with 30%-40% mortality rate. Page | 3 Treatment In the proliferative phase the aim is to eradicate or stunt the growth:  Benign or Watchful neglect with education of parents and regular follow up especially for lesions that are not life or sight threatening.  Pharmacological treatment; which is the first line of treatment in life and sight threatening and disfiguring lesions.  Systemic corticosteroid therapy: Prednisolon 2mg/kg orally. The response rate is 30%-90%. However, it has many side effects.  Interferon α 2A and B: An effective rate of 40% to 50% has been reported. But due to serious neurotoxic side effects it is not recommended.  Nonselective beta adrenergic receptor blocker propranolol: The usual dose is 1 to 3 mg/kg daily. Currently, it is widely used particularly for complicated cases and appears to be the best therapeutic modality.  Laser therapy; pulsed dye laser (PDL) with 0.7-1mm penetration depth for superficial lesions. Nd:YAG laser for lesions in the late proliferative stage. The role of laser therapy for the treatment of hemangioma is controversial.  Surgery in the proliferative stage is reserved for the lesions that do not respond to the non-surgical treatment. In the involutive stage treatment is aimed to improve function and esthetics. Corticosteroids are not effective, the type of treatment depends on the depth of the lesion.  PDL and Nd:YAG laser for superficial lesions.  Surgical resection for deep lesions. Treatment of residual deformities Generally these deformities are treated by Laser and surgery. Page | 4 Vascular Malformations These are errors of morphogenesis that are populated by stable mature vascular endothelium. Both sexes are equally affected. They are always present at birth (though some may not be apparent until a later stage) and in contrast to hemangiomas they never proliferate or involute. Instead, they expand slowly and relentlessly throughout life, in pace with the growth of the patient. Trauma, puberty, and pregnancy can cause accelerated growth. These lesions are subclassified: According to the predominant vessel type: 1. Capillary. 2. Venous. 3. Arteriovenous. 4. Lymphatic. 5. Combined. According to the hemodynamic properties into: 1. High-flow. 2. Low-flow. Unlike hemangiomas, vascular malformations are associated with skeletal abnormalities in up to 35% of cases. Low-flow malformations Capillary (venular) malformations They are made up of postcapillary venules within the papillary and superficial reticular dermis. They present initially as flat pink macules but darken and thicken with age, resulting in a cobblestone appearance. They are thought to result from altered neural modulation of the papillary plexus. Page | 5 They are graded according to the degree of ectasia of the vessels into grades I–IV which correlate well with the clinical features and outcome of treatment. Capillary malformations may be associated with Sturge-Weber and Klippel- Trenaunay syndromes. Treatment The choice of treatment depends on the degree of ectasia (diameter) of the vessels. The primary treatment of capillary malformation is the laser application. Pulsed dye laser is considered the treatment of choice for capillary malformations. It works on the principle of selective thermolysis which is the ability to coagulate a target structure (chromophore) specifically without damaging the surrounding tissues and is dependent on the use of a laser with an appropriate wavelength, energy, and pulse duration. For vascular lesions the target chromophore is oxyhemoglobin and selection of a laser wavelength that is preferentially absorbed by oxyhemoglobin is crucial. Lesions resistant to pulsed dye laser may respond to potassium titanyl phosphate (KTP), copper vapour, argon, and other lasers. However, complications of scarring and hypopigmentation and/or hyperpigmentation are more common with copper and KTP lasers. An average of two to six treatments may be necessary and the response rate is variable. Lesions may recur after treatment, the suggested etiology of the recurrence is that any abnormally innervated vessels in the superficial papillary plexus that were left behind would lead to recurrence. In some cases surgical treatment is needed followed by reconstruction with skin graft, excision of capillary malformation can be performed in a staged procedure. Page | 6 Venous malformations They are characterized by an abnormal collection of veins, which do not have any demonstrable mitotic activity in endothelial cells and often lack a uniform smooth muscle layer. They can be focal, multifocal or diffuse. Up to 60% of venous malformations are located in the head and neck area. The lesions are usually soft, compressible, and enlarge in size when venous pressure is increased due to compression of surrounding tissue or during crying or Valsalva maneuver. Phleboliths may be present in the lesion and they result from gradual calcification of clotted blood in the venous vessels and are pathognomonic for differentiation between venous malformation and hemangioma. Changes in the adjacent skeleton, if present, often take the form of bony hypertrophy or distortion or both. Venous malformations can occasionally be completely intraosseous and the mandible is the most common bone involved, although maxillary, nasal, and frontal lesions have also been reported. Treatment Treatment of venous malformation consists mainly of two different methods: sclerotherapy and surgery that occasionally could be combined. Sclerotherapy is the most widespread method. Sclerosing agents can be divided in the following groups:  Osmotic substances (hypertonic saline/salicylates)  Chemical substances (ethanol/iodine)  Anticancer substances (bleomycin)  Detergents (polidocanol/sodium tetradecyl sulfate/diatrizoate sodium) Recurrence after sclerotherapy can occur and it is thought to be due to recanalization. Page | 7 Surgical treatment of venous malformation is indicated only for small, well- defined lesions that can be easily excised. Resection must be complete to prevent recurrence and appropriate imaging is necessary to show the full extent of the lesion. Larger or diffuse venous malformations requires a combination of sclerotherapy and surgical removal. Certain surgical modifications such as compartmentalization technique have been described in large venous malformations, this procedure entails placing of deep sutures in the lesion dividing it into compartments that are treated with sclerosing agents followed by the surgical resection with a significantly lower risk of bleeding. Cryotherapy and laser have been reported in the treatment of venous malformation. Lymphatic malformations They constitute a spectrum of disorders that present in various ways, often in childhood and adolescence. The majority of lymphatic malformations develop in the head and neck area, particularly in the oral cavity and the clinical manifestation varies according to the extent and depth of the lesions as well as the extent of fibrous reaction around them. Lymphatic malformations are categorized into macrocystic (single or multiple cysts ˃2 cm3), microcystic (