The oral mucosa is similar to the skin with respect to ectodermal derivation, histologic features of stratified squamous epithelium and underlying connective tissue, and significant barrier functions.
The key differences between oral mucosa and skin include the moist environment of the oral cavity influenced by saliva, the presence of a biofilm of microorganisms, the mechanical and chemical stresses of mastication and diet, the presence of teeth, and the specialized sensory function of the taste buds on the tongue.
The oral epithelium has two maturation phases: nonkeratinized and keratinized, with regional differences in the oral cavity determined by function.
Nonkeratinized epithelium, termed lining mucosa, appears moist and flexible and is located on the labial and buccal mucosae, soft palate, floor of the mouth, and ventral surface of the tongue.
Keratinized epithelium, termed masticatory mucosa, is typically parakeratizined but may be orthokeratinized. It appears rubbery and immobile and is located on the hard palate, attached gingiva, and dorsum of the tongue.
The epithelium on the dorsum of the tongue is subcategorized as specialized mucosa due to the presence of taste buds on the papillae of the anterior two-thirds of the dorsal surface.
Physiologic pigmentation is a common normal finding in the oral cavity of persons of color.
This chapter describes the normal oral mucosa as a foundation for understanding the common oral diseases described in Chapters 56 and 57.
The oral mucosa is the lining of the oral cavity, continuous with the skin at the vermilion border of the lips. It has several similarities with skin, including derivation from ectoderm, histologic features of stratified squamous epithelium and underlying connective tissue, and significant barrier functions.
The clinician should also keep in mind important differences between the skin and oral mucosa. The first is the environment to which the oral mucosa is exposed. This environment is influenced by saliva, a variable population of microorganisms, the mechanical stresses of mastication, and chemical effects of diet. Unlike skin, oral mucosa contains minor salivary glands, which contribute to the moist environment. It does not contain skin appendages such as sweat glands and hair follicles, although sebaceous glands can be found in the oral mucosa and are called Fordyce granules (described later). Oral mucosa is coated with a plethora of bacteria, both pathogens and nonpathogens, collectively referred to as bacterial biofilm.1,2,3 The second major difference is the unique presence of teeth that have erupted through the oral mucosa and have a specialized junction located between the crown and root with the critical function of sealing the supporting tissues of the tooth from the oral environment. The third significant difference is the specialized sensory function of the taste buds located on the tongue.
Oral mucosa consists of a surface epithelium supported by fibrous connective tissue (lamina propria). Submucosa ...