The Clinical Significance of Attached Gingiva in the Natural Dentition

<b>Background:</b> The attached gingiva (AG) is the portion of the gingiva firmly bound to the underlying alveolar bone and root cementum, rendering it immobile during functioning. Its dense connective tissue attachment contributes to resistance against mechanical challenges, stabilization of the gingival margin, and dissipation of forces transmitted from the alveolar mucosa. Histologically, AG is characterized by a keratinized epithelium supported by dense collagen fiber bundles, which provide structural integrity to the dento-gingival unit. Clinically, the buccal and lingual width of AG is estimated by subtracting sulcus depth from the total width of keratinized tissue. Although periodontal health may be maintained with minimal AG under optimal plaque control, substantial evidence supports its role in preserving gingival architecture and resisting mechanical trauma. <b>Practical Application:</b> From a clinical perspective, an adequate width of attached gingiva has traditionally been considered necessary to protect the periodontium; however, clinical situations may exist in which its dimension is reduced or absent. Available evidence suggests that a minimal width of approximately 1 mm of attached gingiva may be sufficient to maintain periodontal health under conditions of effective plaque control and absence of inflammation. Nevertheless, when only this minimal dimension is present, the attachment is predominantly derived from the junctional epithelium, which may offer limited mechanical protection to the dento-gingival unit. Within the limits of current evidence, a keratinized tissue width of approximately 3 mm appears to represent a functional threshold associated with increased connective tissue fiber density and enhanced resistance to mechanical trauma. <b>Methods:</b> A narrative review of classical and contemporary literature was conducted to evaluate the morphology, histology, function, and clinical relevance of the attached gingiva. <b>Results:</b> Evidence indicates that when AG width is minimal, reliance on junctional epithelial attachment alone provides limited resistance to mechanical challenges. In contrast, a greater width of AG incorporating connective tissue fiber attachment is associated with improved gingival margin stability, enhanced mechanical protection, and periodontal tissue resilience. Based on this synthesis, a tissue-based clinical categorization of AG is proposed. <b>Conclusions:</b> This review integrates current biological and clinical concepts regarding the functional dimensions of attached gingiva. The proposed categorization offers a practical framework to support clinical decision-making and to identify conditions in which surgical augmentation may be indicated for the management of mucogingival deficiencies.