This article presents an overview of the structures of tooth & oral cavity, The salivary glands, the bones of the jaw, and the articulations between the jaws (temporomandibular joints).
- The Tooth
Teeth constitute approximately 20% of the surface area of the mouth, & they have several functions including Mastication & Speech. Teeth must be hard and firmly attached to the bones of the jaws to fulfill most of these functions.
The tooth structure consists of a hard, inert, acellular Enamel formed by epithelial cells & supported by the less mineralized, more resilient, and vital hard connective tissue Dentin, which is formed and supported by the Dental Pulp, a soft connective tissue. The tooth is attached to the bones of the jaw by tooth-supporting connective tissues, consisting of the Cementum, Periodontal Ligament (PDL), and Alveolar Bone, which provide an attachment with enough flexibility to withstand the forces of mastication.
The face and jaws of a human child are small and consequently carry few teeth of smaller size. These teeth constitute the Deciduous or Primary Dentition. A large increase in the size of the jaws occurs with growth, necessitating not only more teeth but also larger ones. Because the size of the teeth cannot increase after they formed, the deciduous dentition becomes inadequate and must be replaced by a Permanent or Secondary Dentition consisting of more and larger teeth.
Anatomically the tooth consists of a crown and a root. The term Crown denotes that part of the tooth that is visible in the oral cavity.
- Bones of the jaw
As stated before, teeth are attached to bone by the PDL. This bone, the alveolar bone, constitutes the alveolar process. The alveolar process forms in relation to teeth. When teeth are lost, the alveolar process is gradually lost as well, creating the characteristics facial profile of the edentulous person whose chin and nose approximate because of a reduction in facial height. The position of the teeth and supporting tissues, which include the alveolar process, can be modified easily by orthodontic therapy.
- Salivary Glands
Saliva is a complex fluid that in health almostcontinually batches the parts of the tooth exposed within the oral cavity. Consequently, salivarepresents the immediate environment of the tooth. Saliva is produced by three paired setsof major salivary glands – the Parotid, Submandibular, and sublingual glands – and by the many minor salivary glands scattered throughout the oral cavity. A precise account of the composition of saliva is difficult because not only are the secretions of each of the major and minor salivary glands different, but their volume may vary at any given time. Regardless of its precise composition, saliva has several functions:
- Saliva moistens the mouth
- Facilitates Speech
- Lubricates food
- Helps with taste by acting as a solvent for food molecules.
Saliva also contains a digestive enzyme (amylase). Saliva not only dilutes noxious material mistakenly taken into the mouth, it also cleanses the mouth. Furthermore, it contain antibodies and antimicrobial substances, and by virtue of its buffering capacity plays an important role in maintaining the pH of the oral cavity.
- Temporomandibular Joint
The relationship between the bones of the upper and lower jaws is maintained by the articulation of the condylar process of the mandible with the glenoid fossa of the temporal bone. This articulation, the temporomandibular joint (TMJ), is a synovial joint with special features that permit the complex movements associated with mastication. A simplified way to understand the function of the TMJ is to consider it as a joint with the articular disk being a movable articular surface.
Reference: Ten Cate’s Oral Histology by Antonio Nanci
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Haider Maitham DDS