Australasian Dentist Magazine May June 2021

Category 90 Australasian Dentist L IPS are defined as, “either of two fleshy folds that surround the mouth in humans and many other vertebrates and are organs of human speech essential to certain articulations” 1 . Lips are unique oral structures (as individual as fingerprints), which play important roles in mastication and deglutition; sound articulation; facial expression and physiological protection; as well as being tactile organs and erogenous zones. Lips are also the central defining aesthetic feature of the lower third of the face, being distinct from the surrounding skin, contributing significantly to our perceptions of healthy, beauty, vitality and how we interact with our environment. But mention the word LIPS to most Dental Practitioners and their thoughts immediately turn to inconvenient bits of flaccid tissue covering the important stuff underneath, that just get in the way of us doing our job and that we wish were somehow detachable! In fact, even those practitioners who do give greater thought to these oral soft tissues, do so, almost exclusively, from a perspective of screening for pathology or, perhaps in the case of an increasing number of practitioners who offer facial injectable treatments like dermal filler, from a perspective of correcting defects or age-related aesthetic changes, only once they have occurred. Very few dental practitioners acknowledge the importance and uniqueness of lips and include them in their practice as they do the teeth and gums, that is, by focusing on the maintenance health and prevention of disorder, so as to reduce the need for intervention at a later date. This is in large part due to lips (and other facial soft tissues) not being given more than a cursory discussion (at best) during most traditional formal dental training around the world, where the major focus is on the dentition and periodontium. However, this is all set to change with the introduction of a revolutionary professional lip care treatment, (Lip-Tx TM , www.lip-tx.com ) used by Hygienists, Dentists and Therapists, at every patient’s maintenance recall visit or indeed at the end of any dental appointment, designed to pay lips the service they are long overdue. Lips need special treatment The appearance of the lips not only has a major impact on the aesthetic perception of the face in general, but they can be indicators of general health and, as with other aspects of the orofacial complex, are exposed to pathology and deterioration in condition, due to the combined effects of the general ageing process (loss of supportive collagen, elastin&extracellular matrix components); abuse from the constant contraction of the underlying (Orbicularis Oris) muscle; environmental abuses (including exposure to smoking, dental visits/materials, UV radiation) and a lack of care 2 . Lips represent the transition between themucosal membrane and the outer facial skin and, histologically, lips also sit at the crossroads between those tissues. Unlike facial skin, which has a thick, protective keratinized (stratum corneum) surface layer which is around 16 cells thick, lip tissue is comprised of non-keratinized epithelium, which is only around 3 cells thick 3 , a histological difference which is easily recognized by simply looking at the color of the lips in comparison to normal skin (Fig.1.). The red/pink color is the result of the combined effects of a lack of thick keratinized surface, leading to translucence of the underlying capillary network, together with a lack of melanocytes (pigment producing cells found in the epidermis of normal skin and that afford UV protection). 3 But more important than causing a pinkish hue, the lack of a truly protective stratum corneum layer, means that lips have a poor barrier function, with low moisture capacity 4 , leaving them prone to infection, pathology, desiccation and at the mercy of the abuses inflicted on a daily basis – everything from toothbrushing, lip-licking, mouthrinses, eating and UV exposure. Transepidermal Water Loss (TEWL) is the amount of water that passively evaporates through skin to the external environment, not through sweat, but due to water vapor pressure gradient on both sides of the skin barrier. The measurement of TEWL is a good indicator of the integrity of the skin barrier function, with an increase indicating impaired barrier function which correlates to skin ageing and deterioration. 5 Given the structure, it is not surprising to know that research has shown lips to experience significantly greater TEWL than the rest of the skin, with this compromised barrier playing a major role in many common dermatoses including all forms of cheilitis (lip inflammation), leading to dry, chapped lips, cracking, flaking, sores, bleeding and more (Fig.2). Additionally, as Lips do not possess hair follicles, sebaceous or sweat glands like normal skin (which aid hydration and bring vital nutrients and antioxidants like Vitamin E to the skin surface), research has shown that, because of their vulnerable structure, lips lack the innate protection capacity of the surrounding facial skin and experience daily physiological stress and deterioration at a faster rate and to a greater degree. Indeed, lip cancer represents the most common form of head and neck cancer (greater in men than women), with 90 per cent of new cases being squamous cell carcinoma (SCC). SCC originating in the lip has been shown to carry a much higher risk of aggressive metastasis than when the same kind of cancer appears first on other parts of the skin. 6 Many people mistakenly think that Lips: the forgotten oral tissue clinical by Myles Holt, BDS, LLM, FIADFE Fig 1. Myles Holt