Regional Histological Anatomy of the Supraperiosteal Tissues of the Oral Cavity: Implications for Periodontal Flap Surgery and Periosteal Releasing Incisions

Periodontal and implant procedures increasingly involve tissue planes superficial to the periosteum, yet their regional anatomy remains poorly understood. This study conducted a histological investigation of the supraperiosteal anatomy of the oral cavity and its implications for periosteal releasing incisions (PRIs). Intraoral dissection of the mimetic muscle was performed using a fresh anatomical donor. Subsequently, maxillary and mandibular incisor, premolar, and molar regions from five formalin-fixed donors were examined histologically using Masson's trichrome staining. Muscular, neural, vascular, and connective tissue structures within 5 mm of the facial alveolar bone surface were evaluated. Supraperiosteal tissue architecture differed markedly by region. Muscular, neural, and vascular structures showed distinct region-specific distributions. The mental nerve and its branches were identified in the mandibular premolar region, whereas facial and buccal vessels were present near the bone surface in the posterior regions. Muscle attachment and intervening connective tissue also varied regionally. Structures potentially injured during PRI and their associated risks are region-dependent. PRI should therefore be guided by region-specific anatomy and the tissues requiring release for sufficient flap mobility rather than by a predetermined incision depth alone.