The Healthy periodontium
The gingiva is pink, firm in texture and extends from the free gingival margin to the mucogingival line. The interdental papillae are pyramidal in shape and occupy the interdental spaces beneath the contact points of the teeth. Gingiva is keratinised and stippling is frequently present. The gingiva comprises the free and the attached portions. The free gingiva is the most coronal band of unattached tissue demarcated by the free gingival groove, which can sometimes be detected clinically. The depth of the gingival sulcus ranges from 0.5 to 3.0 mm. The attached gingiva is firmly bound to underlying cementum and alveolar bone and extends apically from the free gingival groove to the mucogingival junction. The width of attached gingiva varies considerably throughout the mouth. It is usually narrower on the lingual aspect of the mandibular incisors and labially, adjacent to the canines and first premolars. In the absence of inflammation, the width of the attached gingiva increases with age. The mucogingival line is often indistinct. It defines the junction between the keratinised, attached gingiva and the oral mucosa. Oral mucosa is non-keratinised and, therefore, appears redder than the adjacent gingiva. The tissues can be distinguished by staining with Schiller iodine solution; keratinised gingiva stains orange and non-keratinised mucosa stains purple/blue. This can be used to determine clinically the width of keratinised tissue that remains, for example, in areas of gingival recession.
The crest of the interdental alveolar bone is well defined and lies approximately 0.5-1.5 mm apical to the cementoenamel junction (Fig. ). The periodontal membrane space, often identifiable on intraoral radiographs taken using a paralleling technique, is approximately 0.1- 0.2 mm wide. This accounts for the minimal tooth mobility that is observed when lateral pressure is applied to a tooth with a healthy periodontium.
Epithelial components include (Fig. )
- junctional epithelium cells: non-keratinised and attached to the tooth surface by a basal lamina and hemidesmosomes
- sulcular epithelium: non-keratinised and lines the gingival crevice
- oral epithelium: keratinised and extends from the free gingival margin to the mucogingival line.
Gingival connective tissue core contains ground substance, blood vessels and lymphatics, nerves, fibroblasts and bundles of gingival collagen fibres (dentogingival, alveologingival, circular and trans-septal). The combined epithelial and gingival fibre attachment to the tooth surface is the biologic width, which is typically 2 mm, not including the sulcus depth (Fig. ). Periodontal connective tissues comprise alveolar bone, periodontal ligament, principal and oxytalan fibres, cells, ground substance, nerves, blood vessels and lymphatics, and cementum.