The Clinical Significance of Attached Gingiva in the Natural Dentition

Background: The attached gingiva is the portion of the gingiva that is firmly bound to the underlying alveolar bone and cementum. Its firm attachment to the periosteum and connective tissue renders it immobile during physiologic movements. Functionally, the attached gingiva increases the resistance of the periodontium to mechanical and external injuries, contributes to the stabilization of the gingival margin, and aids in the dissipation of physiological forces exerted by the muscular fibers of the alveolar mucosa onto the gingival tissues. Histologically, it is characterized by keratinized epithelium supported by densely packed collagen fibers, which provide firm anchorage to the underlying bone and cementum and contribute to the structural integrity of the dento-gingival unit. Anatomically, the attached gingiva lies apical to the junctional epithelium and coronal to the alveolar mucosa. Clinically, its width is typically determined by subtracting the sulcus depth from the total width of keratinized tissue, a method that inherently includes the junctional epithelium within the measurement. Although some studies indicate that periodontal stability can be maintained with minimal attached gingiva under optimal plaque control, substantial evidence suggests that its presence remains fundamental for preserving gingival architecture, resisting mechanical trauma, and maintaining periodontal health. Practical Application: From a clinical standpoint, it has been suggested that an adequate width of attached gingiva is necessary to protect the periodontium. Nevertheless, situations may arise in which its dimension is reduced or even absent. It has been suggested that a minimum width of 1 mm of attached gingiva is required to maintain periodontal health and provide protection to the periodontium. However, when only this minimal dimension is present, the attachment is predominantly derived from the junctional epithelium, and such a fragile adherence may not be sufficient to protect the dento-gingival unit against mechanical trauma. Consequently, a width greater than 1mm of attached gingiva should be recommended to ensure adequate mechanical protection and to support long-term stability of the gingival margin. Methods: This narrative review addresses classical and contemporary literature on the morphology, histology, function, and clinical relevance of the attached gingiva. Studies evaluating the width of keratinized and attached tissues, and their influence on periodontal stability, inflammation, and mucogingival conditions were examined to clarify the biological significance of adequate tissue dimensions. Results: When minimal attached gingiva is present, reliance on the junctional epithelium may offer insufficient protection against mechanical trauma. Evidence suggests that a width greater than 1 mm of attached gingiva provides improved mechanical defense, supports the stability of the gingival margin, and contributes to the preservation of periodontal health. A tissue-based categorization of the attached gingiva is proposed to assist clinicians in assessing mucogingival conditions and in determining the need for surgical augmentation. Conclusion: This review consolidates current concepts regarding the dimensions required for the protective and resistance functions of the attached gingiva. The proposed categorization offers a practical framework to guide clinical decision-making, enabling practitioners to accurately evaluate attached gingiva quality and determine when surgical intervention is indicated for managing mucogingival deficiencies.