Introduction to Dental Anatomy PDF

Introduction to Dentistry Introduction to Dental Anatomy Tooth structure Tooth structure  Enamel  Dentin  Cementum  Pulp  The four tooth tissues are, Enamel, Dentin, Cementum, and Pulp. The first three are hard mineralized tissues composed of an organic matrix...

Introduction to Dentistry Introduction to Dental Anatomy Tooth structure Tooth structure  Enamel  Dentin  Cementum  Pulp  The four tooth tissues are, Enamel, Dentin, Cementum, and Pulp. The first three are hard mineralized tissues composed of an organic matrix embedded bycrystalline forms of calcium phosphate salt. The pulp is soft connective tissue.  A-alpha nerve fibers carry information related to proprioception (muscle sense). A-beta nerve fibers carry information related to touch. A-delta nerve fibers carry information related to pain and temperature. C-nerve fibers carry information related to pain, temperature and itch. In the socket of the tooth not tooth itself Proprioception is the sense of self-movement, force, and body  The Crown and Root Each tooth has a crown and root portion. The crown is covered with enamel, and the root portion is covered with cementum. The root is embedded in the jaw bone. The crown and root join at the cementoenamel junction. This junction also called the cervical line. Maxillary central incisor: Apex of root. Root. Cervical line. Crown. sensitivity Incisal edge.  The root portion of the tooth is firmly fixed in the bony process of the jaw, so that each tooth is held in its position relative to the others in the dental arch. That portion of the jaw which serves as a support for the tooth is called the alveolar process.  The crown portion is never covered by bone tissue after it is fully erupted, but it is partly covered at the cervical third in young adults by soft tissue of the mouth known as the gingiva or gingival tissue, or gum tissue. In older persons, all of the enamel and frequently some cervical cementum may be exposed in the oral cavity. The Crown  The Anatomic Crown is that portion of the tooth which is covered by enamel.  The Clinical Crown is that portion of the tooth which is visible in the mouth regardless of whether it corresponds to the anatomical crown.  The anatomical crown is constant in length whereas the clinical crown may change in length throughout life. Clinical Crown Anatomic Crown  The crown of an incisor tooth may have an incisal ridge or edge, as in the central and lateral incisors; a single cusp, as in the canines; or two or more cusps, as on premolars and molars. Incisal ridges and cusps form the cutting surfaces on tooth crowns. The Root  The Anatomical Root is that portion of the tooth which is covered by cementum.  The Clinical Root is that portion of the tooth which is not visible in the mouth. As with crown, the clinical root may change throughout life. Clinical Root Anatomic Root  The root portion of the tooth may be single, with one apex or terminal end, as usually found in anterior teeth and some of the premolars; or multiple, with a bifurcation‫اﻟﺘﺸﻌﺐ‬ ‫ﺛﻨﺎﺋﻲ‬ or trifurcation dividing the root portion into two or more extensions or roots with their apices or terminal ends, as found on all molars and in some premolars. Single Root Double Root, with a bifurcation Triple Root, with a trifurcation Surfaces and Ridges The crowns of the incisors and canines have four surfaces and a ridge, and the crowns of the premolars and molars have five surfaces.  The surfaces are named according to their positions and uses. In the incisors and canines, the surfaces toward the lips are called labial surfaces; in the premolars and molars, those facing the cheek are the buccal surfaces. When labial and buccal surfaces are spoken of collectively, they are called facial surfaces.  The inner surface of any maxillary tooth is called Palatal since it faces the palate of the mouth, and that of the mandibular teeth is called Lingual since it faces the tongue.  The surfaces of the premolars and molars which come in contact with those in the opposite jaw during the act of closure (called occlusion) are called occlusal surfaces. In incisors and canines, those surfaces are called incisal surfaces.  Facial: term used to designate the surface of the tooth toward the face: Buccal {adjacent to the cheek}. Labial {adjacent to the lip}.  Lingual: adjacent to the tongue.  Palatal: adjacent to the palate.  Occlusal (incisal): adjacent to the contacting surface of opposing teeth.  The surfaces of the teeth facing toward adjoining teeth in the same dental arch are called proximal or proximate surfaces. The proximal surfaces may be called either mesial or distal. These terms have special reference to the position of the surface relative to the median line of the face.  This line is drawn vertically through the center of the face, passing between the central incisors at their point of contact with each other in both the maxilla and the mandible.  Those proximal surfaces which, are faced toward the median line, are called mesial surface, and those most distant from the median line are called distal surfaces.  Four teeth have mesial surfaces that contact each other: the maxillary and mandibular central incisors. In all other instances, the mesial surface of one tooth contacts the distal surface of its neighbor, except for the distal surfaces of third molars of permanent teeth and distal surfaces of second molars in deciduous teeth, which have no teeth distal to them. The area of the mesial or distal surface of a tooth which touches its neighbor in the arch is called the contact area.  Proximal: surface of a tooth that is adjacent to another tooth.  Mesial: situated in the middle, median, toward the middle line of the body or toward the centerline of the dental arch.  Distal: away from the median sagittal plane of the face and following the curvature of the dental arch.  Anterior: situated in front of; the forward position.  Posterior: situated behind.  The Roots of the teeth may be single or multiple.  Both maxillary and mandibular anterior teeth have only one root each.  Mandibular first and second premolars, and the maxillary second premolar are single-rooted.  Maxillary first premolar has two roots in most cases, one buccal and one palatal.  Mandibular molars have two roots, one mesial and one distal.  Maxillary molars have three roots, one mesiobuccal, one distobuccal, and one palatal. M3 M2 M1 P2 P1 Ca L Ce Ce L Ca P1 P2 M1 M2 M3  It must be understood that description in anatomy can never follow a hard-and-fast rule. Variations frequently occur. This is especially true regarding tooth roots, e.g., facial and lingual roots of mandibular canine.