Neck lumps

Whilst dental healthcare professionals naturally focus on assessment of the teeth and the supporting tissues, they also have an important role in assessing the whole oro-facial complex and the neck. Assessment of the neck is particularly important, not least, because it contains the regional lymph nodes that are involved in immune surveillance of the head and neck region. The neck also contains the major salivary glands: the sub­mandibular gland and the tail of the parotid gland. Mid-line structures include the hyoid bone, larynx, and trachea, along with the thyroid gland and parathyroid glands. The assessment of these anatomical structures should form part of the routine clinical examination. The dis­covery of an abnormality in the neck, which may not have been noticed by the patient, may expedite the diagnosis of significant disease and facilitate a timely intervention. A through understanding of the anatomy of the neck is essential and informs the clinical examination. It is also important to understand the concept of the anatomical levels that map out the lymph node groups of the neck (Chapter 1; Fig. 1.2). Accurate assessment of the neck is usually best achieved by a combination of visual inspection and palpation, with the patient in a slightly reclined position, the clinician standing behind the patient. Any lumps, e.g. enlarged lymph nodes, are described by anatomical site, size, consistency (cystic, soft, rubbery, hard), whether the lump is mobile or fixed to the underlying tissue, and if palpation elic­its pain or discomfort. The combination of these parameters will help to formulate the differential diagnosis; for example, an isolated hard lump that is fixed to underlying structures is likely to represent meta­static cancer, whereas, bilateral soft lumps that are mobile and painful to palpation are likely to represent lymphadenitis as a consequence of systemic infection. Ultrasound examination can be used to ascertain important informa­tion about a neck lump such as the site (precise anatomical location, superficial or deep), size, consistency (solid or cystic), and multi-focality. Doppler settings can help to establish the vascularity of a lesion and its proximity to major vessels.

Skin diseases affecting the oro-facial region

Examination of the face and hands can identify significant skin diseases and also provide clues to the presence of underlying systemic disease. Many patients ignore even malignant skin tumours because they are often painless, subtle in appearance, and may be slow-growing. Dental healthcare professionals should be aware of how to recognize malig­nant skin tumours. If suspicious, but unsure of the nature of the lesion, the patient should be referred to their general medical practitioner for further evaluation. If malignancy is obvious, then an urgent referral to an appropriate specialist (dermatologist, plastic surgeon, or oral and max­illofacial surgeon) should be made using the ‘2-week wait’ (2WW) path­way (Chapter 1). Benign lesions and inflammatory diseases are more common and are important considerations in the differential diagnosis of head and neck skin abnormalities. It is important that the dental healthcare professional should be able to recognize common skin infections involving the oro-facial region. Some infections, such as erysipelas, can mimic cellulitis associated with a dental infection. When infection is diagnosed, it is vital to consider the underlying or predisposing factors, as these may be not only important diagnoses, but also may require treatment to achieve an effective clin­ical outcome. The adage ‘infection is the disease of the diseased’ is a useful reminder when dealing with patients presenting with infection. Direct inoculation of Streptococcus into skin through minor trauma is the most common initiating factor for erysipelas, which occurs in iso­lated cases. Infection involves the upper dermis and, characteristically, spreads to involve the dermal lymphatic vessels. Clinically, the disease starts as a red patch that extends to become a fiery red, tense, and indurated plaque. Erysipelas can be distinguished from cellulitis by its advancing, sharply defined borders and skin streaking due to lymphatic involvement. The infection is most common in children and the elderly, and whilst classically a disease affecting the face, in recent years it has more frequently involved the leg skin of elderly patients. Although a clinical diagnosis can be made without laboratory testing, and treat­ment is antibiotic therapy, when the diagnosis is suspected in dental practice, referral to a medical practitioner is recommended.

Disorders of bone

Most invasive dental procedures involving removal of teeth or bone are followed by uneventful healing. However, dentists should be aware that generalized abnormalities of bone, such as osteoporosis and Paget’s dis­ease of bone, may complicate these procedures and, rarely, can lead to ongoing clinical problems. The effects of radiotherapy to the jaws and bisphosphonate treatment are well-described causes of osteonecrosis and delayed healing. Diagnosis of bone disorders often depends on integrating the results of clinical, imaging, pathological, genetic, and biochemical investigations. Although the bony skeleton is often thought of as forming just a rigid framework, it should be remembered that bone is a living, responsive tissue that plays an important role in metabolism. During development, some bones develop from a cartilaginous template and others, such as most of the craniofacial bones, form in fibrous membranes. Bone matrix is laid down by osteoblasts that are derived from the extensive meshwork of bone-lining cells that cover the bone surfaces. The bone matrix contains osteocytes that are responsive to mechanical stresses. Bone matrix is removed by osteoclasts that move over the bone sur­face, resulting in scalloped pits termed Howship’s lacunae. Bone mat­rix can be woven or lamellar in pattern. Pathologists often examine sections of bony lesions in polarized light to determine whether the pattern of the collagenous matrix is woven or lamellar, because it can be pivotal for diagnosis. It is also important for clinicians to be aware that, in order to produce a histological section of bone, the tissue must first be fixed and then demineralized to soften the matrix. When a bone biopsy is performed, the patient should be made aware that additional time will be needed to process the biopsy. Following extraction of a tooth, the socket rapidly fills with blood, which then clots. Granulation tissue, which consists of proliferating endothelial cells and fibroblasts derived from remnants of the periodontal ligament and surrounding alveolar bone, grows into the clot and organization commences. Osteoclasts begin to remodel the crestal bone and remove any small spicules of bone detached during the extraction.

Diseases of the teeth and supporting structures

A wide variety of processes can affect the formation of teeth during development. The number, size, shape, and quality of dental hard tis­sue may be abnormal and teeth may erupt early or be prematurely shed or resorbed. When a child presents with a tooth abnormality, the clin­ical and radiographic features are often distinctive and management depends on diagnosis (Box 5.1). Broadly, developmental abnormal­ities of the teeth can be either genetically determined or acquired as a result of injurious processes affecting the developing teeth. It can be problematic to make a diagnosis, particularly when teeth initially erupt. Sometimes pathological examination of a shed or extracted tooth by ground sectioning (for enamel) or conventional sectioning of a decalci­fied tooth can provide a diagnosis. Research has provided insights into the genetic and structural basis of dental anomalies, and has resulted in a complex and extensive classification of subtypes. Minor abnormal­ities, such as failure of development of a few teeth or enamel erosion in adult life, may be dealt with in general dental practice, but it is advisable to refer younger patients with more complex or extensive dental abnor­malities to a specialist in child dental health, with links to expert diag­nostic facilities and input from orthodontic and restorative colleagues. The publically available Online Mendelian Inheritance in Man (OMIM) database provides an invaluable resource for genetic disorders, including dental abnormalities. Supernumerary teeth are common and may be rudimentary in form or of normal morphology, when they are referred to as supplemental teeth. The most common supernumerary tooth occurs in the mid- line of the maxillary alveolus and is referred to as a mesiodens, which usually has a conical shape. Eruption of adjacent normal successor teeth may be impeded by a mesiodens, which is an indication for its removal. Most supernumerary teeth occur as a sporadic event in devel­opment, but multiple extra teeth can be found in certain developmen­tal disorders. Failure of development of tooth germs results in teeth missing from the dental arch and is referred to as hypodontia. Most often the missing teeth are third molars, second premolars, and upper lateral incisors. Hypodontia is more common in the permanent dentition than in the primary teeth.

Salivary gland diseases

The salivary glands consist of three paired major glands—parotid, sub­mandibular, and sublingual—and the countless minor salivary glands found in almost every part of the oral cavity, except the gingiva and anterior regions of the hard palate. The secretion of saliva is essential for the normal function and health of the mouth, and disorders of salivary gland function predispose to oral disease. Functional disorders in salivary secretion may be associated with primary salivary gland disease but in other cases are a consequence of systemic factors, such as medi­cations, endocrine disturbances, and neurological disease, which are discussed in Chapter 10. Developmental anomalies of the salivary glands are rare. Aplasia of one or more major glands and atresia of one or more major salivary gland ducts have been reported. Congenital aplasia of the parotid gland may be associated with other facial abnormalities, e.g. ectodermal dysplasia, mandibulofacial dysostosis, and hemifacial microsomia. Heterotopic salivary tissue has been reported from a variety of sites in the head and neck region, the most frequent being its inclusion at the angle, or within the body, of the mandible, called a Stafne bone cavity. It is usually an incidental radiological finding and appears as a round or oval, well-demarcated radiolucency between the premolar region and angle of the jaw, and is typically located beneath the inferior dental canal. The radiographic appearances are due to a saucer-shaped depression or concavity of varying depth on the lingual aspect of the mandible, which contains salivary tissue in continuity with the submandibular gland. Accessory parotid tissue within the cheek or masseter muscle is rela­tively common and is subject to the same diseases that may affect the main gland. Age changes can be detected in both major and minor salivary glands. Reduction in the weights of submandibular and parotid glands has been reported with increasing age, associated in the submandibular gland with an age-dependent reduction in flow rates. By contrast, sev­eral studies have demonstrated that there is no significant reduction in parotid flow rates in the elderly.

Oral cancer

The term ‘oral cancer’ encompasses all malignant neoplasms affecting the oral cavity. The majority, greater than 90%, are squamous cell car¬cinomas. The remainder are uncommon and comprise minor salivary gland adenocarcinomas, malignant melanoma, sarcomas, haemato-logical malignancies, and metastases to the oral cavity from cancers at other sites. Oral squamous cell carcinoma is a malignant epithelial neoplasm that arises from the lining mucosa of the oral cavity. The tumour shows vary¬ing degrees of squamous differentiation and is characterized by invasion of local structures and metastasis to regional lymph nodes, followed by metastasis to other organ systems (e.g. lungs and bones) later in the course of the disease. Epidemiological data pertaining to oral cancer can be difficult to evalu¬ate because of variations in the methods of data collection (Box 3.1). Notwithstanding these confounding variables, a database produced by the International Agency for Research on Cancer (GLOBOCAN), esti-mated there were over 400,000 new cases of lip, oral, and pharyngeal cancer worldwide in 2012, placing the disease in ninth position with breast, prostate, lung, colorectal, cervical, stomach, liver, and uterine cancer being more common. These data suggest that oral cancer is uncommon, but there are enormous variations worldwide. Whereas oral cancer is relatively uncommon in the UK, accounting for 2% of all cancers, in India and parts of South-East Asia it is the most common malignant neoplasm and accounts for around a third of all cancers. Furthermore, the incidence rates for large countries, such as India and the USA, conceal regional and ethnic variations. For example, incidence rates tend to be higher in urban as opposed to rural communities, and in the USA are higher for blacks than whites. In the United Kingdom, inci¬dence rates are slightly higher in Scotland than in England and Wales. In the United Kingdom the incidence of oral cancer is 9 per 100,000 of the population, which represents around 6,800 new cases per annum. The disease is more common in men than in women; the male:female ratio is currently 2:1. Oral cancer incidence increases with age, and the majority of cases (greater than two-thirds) are diagnosed after the age of 50 years old; less than 5% occur in individuals below the age of 40 years old.

Jaw cysts and odontogenic tumours

Odontogenic cysts and tumours arise from inclusion of tooth-forming epithelium and mesenchyme in the jaw bones during development. Cysts also arise from non-odontogenic epithelium trapped during fusions or from vestigial structures. In addition, bone cysts that can arise at other skeletal sites may also occur in the jaws. Odontogenic cysts and tumours may be classified according to their putative developmental origins and biology. The classification of jaw cysts is shown in Fig. 6.1. Odontomes are hamartomatous develop­mental lesions of the tooth-forming tissues. Odontogenic tumours are uncommon and are usually benign. Ameloblastoma is the most com­mon odontogenic tumour and is described in detail. The other odon­togenic tumours are rare and only the principal features are presented. Very rare congenital lesions of possible odontogenic origin are men­tioned in the final section. A cyst may be defined as pathological cavity lined by epithelium with fluid or semi-fluid contents. However, clinically, the term encompasses a broader range of benign fluid-filled lesions, some of which do not possess an epithelial lining. The preferred definition is, therefore, ‘a pathological cavity having fluid or semi-fluid contents that has not been created by the accumulation of pus’. Cysts are commonly encountered in clinical dentistry and are generally detected on radiographs or as expansions of the jaws. Most cysts have a radiolucent appearance and are well circumscribed, often with a corticated outline. At least 90% of jaw cysts are of odontogenic origin. The clinico-pathological features of jaw cysts are summarized in Table 6.1. The incidence of the four most common jaw cysts are provided in Table 6.2. The epithelial lining of odontogenic cysts originates from residues of the tooth-forming organ. • Epithelial rests of Serres are remnants of the dental lamina and are thought to give rise to the odontogenic keratocyst, lateral periodon­tal, and gingival cysts. • Reduced enamel epithelium is derived from the enamel organ and covers the fully formed crown of the unerupted tooth. The dentiger­ous (follicular) and eruption cysts originate from this tissue, as do the mandibular buccal and paradental cysts. • Epithelial rests of Malassez form by fragmentation of Hertwig’s epi­thelial root sheath that maps out the developing tooth root. Radicular cysts originate from these residues.

Oral manifestations of systemic disease

This chapter emphasizes the importance of oral disease in the context of systemic disease. Oral disease may be the first sign of an underlying systemic disorder, which should trigger further investigations or referral to a medical or specialist practitioner, expediting early diagnosis and appropriate clinical care. In those patients with known illnesses, dental healthcare professionals should have an appreciation of the effects of these diseases on the oro- facial complex; patients can then benefit from the supportive care of the dental team. Coeliac disease (gluten-induced enteropathy) is a genetically deter­mined inflammatory small bowel disease that is induced by gluten in the diet. Gluten is present in wheat, rye, and barley. The inflammatory reaction results in malabsorption due to morphological abnormalities in the small intestinal mucosa. It was once thought of as a rare disease of childhood, but now it is understood to be a common disease that can be diagnosed at any age. Studies undertaken since the advent of sero­logical screening indicate a prevalence of 0.5–1% in the population, with adult presentations now more frequent than childhood ones. This new appreciation has led to the concept of the ‘coeliac iceberg’. At the tip of the iceberg are those with overt disease, with the lower groups classified in order as: silent coeliac disease, latent coeliac disease, and healthy individuals with genetic susceptibility. Severe presentations in childhood classically were of diarrhoea, failure to thrive, and weakness. However, it is now understood that patients with coeliac disease may have minimal gastrointestinal symptoms of malabsorption at presenta­tion and experience other rather non-specific symptoms of the disease. The increasing recognition of the disease is attributed to several factors, including new serological assays, advances in flexible endoscopy allow­ing clinicians to take duodenal biopsies more easily, and an increased index of suspicion in looking for the disease. The disease is associated with an increased rate of osteoporosis, infertility, autoimmune diseases, and malignancy, especially lymphoma. Treatment should involve a gluten-free diet, which is a major undertaking and for which dietetic advice is essential.

Diseases of the oral mucosa

The oral mucosa lines the oral cavity and comprises a surface squamous epithelium with underlying lamina propria. Below the mucosa is the submucosa, which is composed of fibrous tissue and adipose tissue, and contains lobules of minor salivary glands and neurovascular bundles. In places, there is no submucosa and the lamina propria is continuous with periosteum, forming the resilient mucoperiosteum that covers the maxilla and mandible. The squamous epithelium is composed of keratinocytes arranged in lay­ers: there is a basal cell layer that rests on the basement membrane, a prickle cell layer, and usually a keratinized layer. The keratino­cytes are attached to each other by desmosomes and the basal keratino­cytes are attached to the basement membrane by hemi- desmosomes. The basement membrane is important in maintaining the integrity of the mucosa by sticking the squamous epithelium to the underlying lamina propria. There are two patterns of keratinization: par­akeratosis and orthokeratosis. In parakeratinized epithelium the surface keratinocytes become flattened and the nucleus becomes dark and shrunken (pyknotic). These terminally differentiated squamous cells are eventually lost at the surface by desquamation. In orthokeratiniza­tion, there is a granular cell layer (containing numerous keratohyaline granules) between the prickle cell layer and the keratinized layer. The surface squames become flattened and do not contain any discernible nuclear material. Whilst the majority of cells in squamous epithelium are keratinocytes, there are also accessory cells such as melanocytes, Langerhans cells, and neurosensory cells (Merkel cells and taste buds). The lamina propria is the connective tissue that lies immediately below the epithelium. It is divided into the superficial papil­lary layer (sometimes referred to as the corium) and the deeper reticu­lar layer. The lamina propria is composed of fibrous tissue with a rich neurovascular supply and contains fibroblasts that elaborate collagen and elastin fibres along with other extracellular matrix proteins. The lamina propria also contains components of the mucosal immune defence system such as Langerhans cells, macrophages, mast cells, and lymphocytes. The clinical appearance of the oral mucosa is dependent on the thick­ness of the epithelium, the amount of surface keratinization, melanin (and other) pigmentation, and the vascularity of the lamina propria.

Diagnosis of oral disease

The most common oral diseases are dental caries and periodontal dis­ease. The diagnosis and treatment of these diseases are the focus of the majority of dentists, dental therapists, and dental hygien­ists. Nevertheless, it is the responsibility of the dental healthcare pro­fessional to provide a holistic approach to management that ensures both good oral and general health for their patients. A broad knowledge of the range of diseases that affect the oral cavity is essential and also an appreciation that oral disease may be the first sign of an underlying systemic disease. Before this knowledge can be applied, the clinician must obtain an accurate patient history and undertake a systematic clinical examination. These key clinical skills underpin both medicine and dentistry, and are an absolute requirement to formulate a differ­ential diagnosis. The use of imaging modalities and laboratory tests are often required to reach a definitive diagnosis, and it is the justification and informed choice of these additional investigations that will facili­tate a timely and accurate diagnosis. Following diagnosis, appropriate treatment can be instituted, the ideal outcome being a return to health or control of the patient’s symptoms in recalcitrant chronic diseases. Obtaining a clear and precise clinical history is essential. The clinician must listen carefully to the information conveyed by the patient and then use direct questioning to collect additional data to construct an accurate picture of the patient’s problem. This can be a significant challenge and requires excellent communication skills to build a good patient–clinician relationship. The most common presenting problems relate to pain or the development of a lesion: swelling, lump, ulcer, or white/red patch. To establish a comprehensive pain history, the features listed in Table 1.1 should be addressed. Obtaining an accurate history for a lesion is dependent on the patient noticing the abnormality in the first instance and, as a consequence, the information may be rather vague; however, it is important to ascertain the key points listed in Table 1.2. A comprehensive medical history (Box 1.1) will identify any concur­rent disease that may be relevant to the presenting oral condition (Chapter 10) and highlight any issues relating to proposed medical or surgical interventions.