CLINICAL
Cryotherapy in dentistry Could cryotherapy possibly be used in the future as part of routine daily practice in the dental environment?
Maria Ioana Onicaş, Romania
T
he term ‘Cryotherapy’ is derived from the Greek word “kryos’’ unsurprisingly meaning “cold”. In medicine, it refers to local or general treatments done with, or at low temperatures. It can even refer to an ice-pack used on an injured area of the body, but the most frequent use of the term is in relation to the surgical treatment specifically known as cryosurgery - ’the use of freezing as a special surgical technique to destroy or excise tissue’ (McGraw-Hill Dictionary of Scientific and Technical Terms). Fundamentally, the way cryosurgery works is simple. Usually, an extremely cold liquid, or an instrument called cryoprobe that is cooled with cryogens, is placed in contact with the diseased tissue. Cryogens are substances with a very low boiling point and those commonly used include liquid nitrogen, liquid nitrous oxide, solidified CO2 (known as ‘dry ice’), a mixture of dimethyl ether and
propane, used as a freeze-spray, and compressed argon gas (Sharma et al., 2009; National Cancer Institute, 2005). Cryotherapy can be performed in both open and closed systems (Sunitha, 2010). An open system involves direct application of the cryogen with cotton pellets or as a spray. The heat from the tissue is released by vapourisation due to a drop in temperature. It is generally used for the treatment of medium-to-large oral lesions with smooth or rough surfaces. A closed system implies direct contact between the cryoprobe and the lesional surface. Due to the miniscule surface area of the tip of the cryoprobe, this system is suitable for the treatment of small and smooth-surfaced oral lesions. In contrast to the open system, this method is preferred when control over the depth of the lesion is needed. Cryosurgery may be used for both internal and external le-
sions and tumours. When lesions requiring treatment are located within the body, surgeons place the cryoprobe in contact with the area in question by using ultrasound or magnetic resonanceimaging to guide the position of the cryoprobe (National Cancer Institute, 2005). In this case, the frozen tissue is absorbed by the body. When target sites are on external surfaces, the iced tissue disintegrates and a subsequent crust is formed.
Physiological mechanism
After applying the cold instrument or liquid, the target tissue produces three basic physiological responses (Bazaid et al., 2018): 1. a reduction in the local blood flow 2. a decrease in metabolic activity 3. neural receptor inhibition in the subcutaneous tissues and skin.
Spring 2021
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