“Periodontology” is the study of the tooth-supporting tissues, the “periodontium.” The periodontium is made up of those tissues that surround each tooth and which anchor each tooth into the alveolar process (Greek: para = adjacent, odus = tooth).
The following soft and hard tissues constitute the structure of the periodontium:
• Periodontal Ligament
• Root Cementum
• Alveolar Bone
The structure and function of these periodontal tissues have been extensively researched (Schroeder 1992). Knowledge of the interplay between and among the cellular and molecular components of the periodontium leads to optimum therapy, and also helps to establish the goals for future intensive research.
Gingivitis – Periodontitis
There are numerous diseases that affect the periodontium. By far the most important of these are plaque-associated gingivitis (gingival inflammation without attachment loss) and periodontitis (inflammation-associated loss of periodontal supporting tissues).
Gingivitis is limited to the marginal, supracrestal soft tissues. It is manifested clinically by bleeding upon probing of the gingival sulcus, and in more severe cases by erythema and swelling, especially of the interdental papillae (Fig. 3).
Periodontitis can develop from a pre-existing gingivitis in patients with compromised immune status, the presence of risk factors and pro-inflammatory mediators, as well as the presence of a predominately periodontopathic microbial flora. The inflammation of the gingiva may then extend into the deeper structures of the tooth-supporting apparatus. The consequences include destruction of collagen and loss of alveolar bone (attachment loss). The junctional epithelium degenerates into a “pocket” epithelium, which proliferates apically and laterally. A true periodontal pocket forms. Such a pocket is a predilection site and a reservoir for opportunistic, pathogenic bacteria; these bacteria sustain periodontitis and enhance the progression of the disease processes (Fig. 4).
Gingival recession is not actually a “disease,” but rather an anatomic alteration that is elicited by morphology, improper oral hygiene (aggressive scrubbing), and possibly functional overloading.
Teeth are not lost due to classical gingival recession, but patients may experience cervical hypersensitivity and esthetic complications. If gingival recession extends to the mobile oral mucosa, adequate oral hygiene is often no longer possible. Secondary inflammation is the consequence.
In addition to classical gingival recession, apical migration of the gingiva is often observed in patients with long-standing, untreated periodontitis, and it may be a consequence of periodontitis therapy in elderly patients (“involution”; Fig. 2).
These three periodontal disorders – gingivitis, periodontitis, gingival recession – are observed world-wide; they affect almost the entire population of the earth to greater or lesser degree. In addition to these common forms of oral pathology, there are many less frequently encountered diseases and defects of the periodontal tissues. All of these diseases were comprehensively classified at an international World Work-shop in 1999 (see Appendix, p. 327).