Periodontium Structure

Other details of formation of dentition, subtypes and the formula for human dentition are outlined in APPENDIX A-1, A-2 and A-3 (4, 5, 6). Since this study focuses on the supportive structures of teeth called periodontium, it is discussed in subsequent paragraphs.

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1.2. Periodontium

The supporting structures of tooth are collectively known as periodontium. A normal healthy periodontium (Figure 3) provides the support necessary to maintain the functioning of the tooth.

(a) (b)

Figure 3: a. The periodontium (www.dhonline.chattanoogastate.edu); b. Normal gingiva of young adult. The arrows indicate demarcation between the attached gingiva and the darker alveolar mucosa (7)

The periodontium consists of four principal components:

Gingiva: It is

It transmits the occlusal forces to the bones and acts as a shock absorber (Figure 4). It maintains the gingival tissues in their proper relationship to the teeth. It also shows a nutritional and sensory function (8).

Figure 4: Function of periodontal ligament during shock absorption; a. Mandibular premolar in resting state; b. when force is exerted the tooth rotates around the axis of rotation (black circle on tooth) the periodontal ligaments are compressed in area of pressure and distended in areas of tension (8)

Cementum: It is the calcified, avascular mesenchymal tissue that forms the outer covering of the anatomic root. The two main types of cementum are acellular (primary) and cellular (secondary) cementum, consisting of calcified interfibrillar matrix and collagen fibrils.

Function: It is the surface for the attachment of periodontal ligament. It adapts to wear and tear on the occlusal surfaces of the teeth by deposition in the apical area of the tooth root (8).

Alveolar bones: The alveolar process is the portion of the maxilla and the mandible. These are tooth dependent bony structures that consists of an external plate

It can be regarded as the next progressive stage of gingivitis, the inflammation of gingiva in which the junctional epithelium remain attached to the tooth at its original level (14).

Plaque-induced periodontal diseases have traditionally been divided into three general categories: health, gingivitis, and periodontitis. In this context, the diagnosis of health implies that there is an absence of plaque-induced periodontal disease; Plaque-induced gingivitis is the presence of gingival inflammation without loss of connective tissue. Plaque-induced periodontitis is the presence of gingival inflammation at sites where there has been apical migration of the epithelial attachment onto the root surfaces accompanied by loss of connective tissue and alveolar bone (15).

Figure 9: Healthy Teeth, Gingivitis and Periodontitis