Introduction to Periodontics PDF

Dr. Nawal Khalifa Babiker. ( BDS,PG Diploma, MD Perio.) Introduction  The periodontium consists of the investing and supporting tissues of the tooth: gingivae, periodontal ligament, cementum, and alveolar bone.  It has been divided into two parts: 1- the gingivae, the main function of which is pr...

Dr. Nawal Khalifa Babiker. ( BDS,PG Diploma, MD Perio.) Introduction  The periodontium consists of the investing and supporting tissues of the tooth: gingivae, periodontal ligament, cementum, and alveolar bone.  It has been divided into two parts: 1- the gingivae, the main function of which is protecting the underlying tissues, and 2- the attachment apparatus, composed of the periodontal ligament, cementum, and alveolar bone.  The cementum is considered a part of the periodontium because, with the bone, it serves as the support for the fibers of the periodontal ligament. The gingivae is the part of the oral mucosa that covers the alveolar processes of the jaws and surrounds the necks of the teeth.  The gingivae in health is pink and firm with a knife-edge appearance, scalloped around the teeth.  In certain ethnic groups the gingivae may be pigmented.  In health, the gingival margin is a few millimetres coronal to the cement–enamel junction.  The gingival sulcus (or crevice) is a shallow groove which may be between 0.5 and 3 mm in depth around a fully erupted tooth.  The gingival tissues are keratinised and appear paler pink than sites of non-keratinised oral epithelium. Clinical Features  Normal gingivae covers the alveolar bone and tooth root to a level just coronal to the cementoenamel junction.  The gingivae is divided anatomically into : 1-Marginal. 2- Attached. 3- Interdental areas. Gingival fibers  The functions of these fibers are:  a. To stabilize the attached gingivae to the alveolar process.  b. To stabilize the attached gingivae to the tooth.  c. Helps to maintain the epithelial seal to the tooth.  d. To provide stability to the tooth.  e. To brace marginal/free gingivae firmly against the tooth and adjacent attached gingivae.  f. To provide rigidity to withstand forces of mastication without being deflected away from the tooth surface. Principal group of fibers Secondary group of fibers Periodontal ligament  The attachment apparatus of the tooth includes the periodontal ligament, cementum and alveolar bone.  Periodontal ligament is the soft, specialized connective tissue situated between the cementum covering the root of the tooth and bone forming the socket wall.  Its width ranges from 0.15 to 0.38 mm.  CONSTITUENTS A. Periodontal ligament fibers B. Cellular elements. C. Ground substances i. Glycosaminoglycans ii. Glycoproteins Cementum Cementum is calcified avascular mesenchymal tissue that forms the outer covering of the anatomic root. FUNCTIONS  1. Cementum provides attachment to the collagen fibers of periodontal ligament to the root.  2. Cementum functions as a covering for the root surface, a seal for the open dentinal tubules thus, preventing dentinal sensitivity.  3. Cementum aids in maintaining the teeth in functional occlusion.  4. It contributes to the process of repair after damage to the root surface. CLASSIFICATION Cementum can be classified as:   1. According to location: i. Radicular cementum ii. Coronal cementum  2. According to cells present: i. Acellular cementum is the first cementum to be formed and covers approximately the cervical third or half of the root; it does not contain cells. This cementum is formed before the tooth reaches the occlusal plane. ii. Cellular cementum, forms after the tooth has reached the occlusal plane. It contains cementocytes in individual spaces (lacunae) that communicate with each other through a system of anastomosing canaliculi.  3. According to fibers present: Alveolar Bone  It is the portion of maxilla and mandible that forms and supports the tooth sockets (alveoli).  Alveolar bone is a specialized connective tissue that is mainly characterized by its mineralized organic matrix. Together with the root cementum and periodontal ligament, the alveolar bone constitutes the attachment apparatus of the teeth.  The main function is to distribute and reabsorb forces generated by mastication and other tooth contact.  In addition, the jaw bones consist of the basal bone, which is the portion of the jaw located apically but unrelated to the teeth  PARTS The alveolar process is divisible into separate areas on an anatomic basis (, but it functions as a unit, with all parts interrelated in the support of the teeth.  1. Alveolar bone proper: Thin lamella of bone that surrounds the root of the tooth and gives attachment to principal fibers of the periodontal ligament is called as alveolar bone proper.  2. Supporting alveolar bone: Bone that surrounds the alveolar bone proper and gives support to the socket is called as supporting alveolar bone. It consists of 2 parts: i. Cortical plates: Which consists of compact bone and form the outer and inner plates of the alveolar bone. ii. Spongy bone: Which fills the area between these plates and alveolar bone proper. It is also called as trabecular bone or cancellous bone.  FENESTRATION AND DEHISCENCE The anatomy of the alveolar processes depends upon the alignment and position of the teeth. When the teeth are in extreme buccal or lingual version the alveolar process is extremely thin or missing on that side of the teeth.  Fenestrations are the isolated areas in which root is denuded of bone and marginal bone is intact.  Dehiscences are the denuded areas that extend through the marginal bone  References:  Periodontics Revisited, Shalu Bathla.  Clinical Periodontics, Carranza.