Dental Anatomy Chapter 2 PDF

1. The **clinical crown** is only that part which is seen above the gingiva and seen inside the mouth. Any part of the unerupted crown is not a part of what is visible above the gingiva and is therefore not a part of the clinical crown of the tooth. If the entire anatomic crown does...

1. The **clinical crown** is only that part which is seen above the gingiva and seen inside the mouth. Any part of the unerupted crown is not a part of what is visible above the gingiva and is therefore not a part of the clinical crown of the tooth. If the entire anatomic crown does not erupt, the part that is visible is considered the clinical crown and the unerupted portion is part of the clinical root. The tooth has **coronal, cervical, and apical areas**. 2. The root is held in its position relative to the other teeth in the dental arch by being firmly anchored into the bony section (process) of the dental arch called the **alveolar process**. The bony socket in which the tooth fits into its place is called the **alveolus**. Teeth in the upper part of the jaw are called maxillary teeth because they are anchored into the maxilla. In the lower jaw they\'re called mandibular teeth because they are anchored into the bone called the mandible. 3. The four tooth tissues are **enamel, dentin, cementum, and dental pulp**. The first three are hard tissues and the pulp is soft tissue. 4. One form, called **reparative dentin**, can quickly form in response to injuries such as deep decay, fracture, or when the tooth is subjected to bacterial invasion. **Tertiary dentin** can be initiated by many different traumas including the following: cracked teeth, occlusal trauma, leaky restorations, exposure into the pulp cavity, deep carries, slowly developing caries, deep restorations, attrition, abrasion, erosion, and any other traumas causing damage to the primary dentin. 5. The functions of teeth vary, depending on their individual shape and size and their location in the jaws. The three basic food processing functions of the teeth are cutting, holding, and grinding. 6. The **line angle** separates two surfaces of a tooth by forming the junction of the two surfaces. For instance, the junction of the buccal surface and the occlusal surface of a tooth is a line angle because the line angles are named according to the surface is they join, the line angle that separates the buckle and the occlusal surfaces is called the bucko occlusal line angle. Line angles are named by their proximal name (mesial or distal) first and their incisal or occlusal surfaces last. 7. A **point angle** is the point at which three surfaces meet. For instance, the point at which the mesial, labial, and incisal surface is joined is called the mesiolabioincisal point angle. The point angles are named in this order: first the proximal surface, then the facial or lingual, and then the incisal or occlusal last. 8. When the crowns of teeth are formed, they develop from four or more growth centers called **lobes.** 9. The most obvious landmarks on the posterior teeth are the cusps. 10. The number varies according to the tooth and these cusps are formed by four ridges. The most obvious of which are the triangular ridges. **Triangular ridges** are the main ridges on each cusp that run from the tip of the cusp to the central part of the occlusal surface. 11. Anterior teeth show two developmental depressions (grooves) on their labial surface. These two grooves separate three lobes (mesial, middle and distal) that form the labial surface. The fourth developmental lobe of anterior teeth occurs on the lingual surface of the crown. The fourth lobe is the cingulum, and it makes up the bulk of the cervical third of the lingual surface of any anterior tooth. 12. A **transverse ridge** is the union of two triangular ridges, a buccal and a lingual, which cross the occlusal surface of a posterior tooth. 13. Occlusion and Malocclusion Occlusion is defined as the relationship between the maxillary and mandibular teeth when the upper and lower jaws are in a fully closed position. 14. **Occlusion** also refers to the relationship between the teeth in the same arch. Occlusion-related problems could affect the teeth, joints, and muscles of the head and neck and cause periodontal trauma 15. Centric occlusion occurs when the jaws are closed in a position that produces maximal stable contact between the occluding surfaces of the maxillary and mandibular teeth. In this position, the condyles are in the most posterior, unstrained position in the glenoid fossa. Centric occlusion serves as the standard for a normal occlusion. In normal occlusion, the lingual cusps of the posterior maxillary teeth fit into the central fossae of the occlusal surfaces of the posterior mandibular teeth. This positioning allows effective grinding of food. Functional occlusion, also known as physiologic occlusion, is the term used to describe contact of the teeth during biting and chewing movements. 16. Malocclusion refers to abnormal or malpositioned relationships of the maxillary teeth to the mandibular teeth when they are in centric occlusion. The basis of this system is that the permanent maxillary first molar is the key to occlusion. 17. Angle\'s classification system was developed in 1890 by Dr. Edward H. Angle to describe and classify occlusion and malocclusion. The Angle classifications are based on the relationship of the buccal groove of the mandibular permanent first molar and the mesiobuccal cusp of the maxillary first permanent molar. This classification is considered to be one of the most commonly used methods for identifying misalignment for molars. Angle\'s system assumes that the patient is occluding in a centric position.