Essential Anatomy Risks in Third Molar Surgery You Must Know

Successful removal of mandibular third molars is not defined solely by the extraction itself, but by the preservation of the delicate anatomical structures surrounding them. Complications such as paresthesia, altered taste, periodontal defects, or space infections often originate from an inadequate understanding of local anatomy. A systematic approach to identifying risk-bearing structures pre-operatively can drastically reduce morbidity and enhance patient outcomes. 

Structures You Can’t Afford to Miss 

Here are the key anatomical landmarks every practitioner must identify and respect during third molar disimpaction: 

1. Inferior Alveolar Nerve¹ (IAN) 

• Location: The IAN travels through the mandibular canal and is often closely associated with the roots of impacted third molars, especially in the posterior mandible. 

• Risk: Injury to the IAN during extraction can result in sensory disturbances such as numbness or tingling in the lower lip, chin, and mandibular teeth—effects that may be temporary or permanent. 

• Tip: Preoperative imaging, particularly CBCT, is strongly recommended to assess the proximity of the nerve to the tooth roots and to guide surgical planning. 

2. Lingual Nerve² 

• Location: The lingual nerve lies medial to the mandible and often just beneath the oral mucosa in the third molar region. Its course is highly variable and may be superficial, increasing the risk of injury during flap elevation. 

• Risk: Damage can result in altered sensation or loss of taste in the anterior two-thirds of the tongue, which may be temporary or permanent. 

• Tip: Avoid excessive medial flap reflection and use blunt dissection. Since the nerve is not reliably visible on imaging, tactile awareness and anatomical caution are essential. 

3. Retromolar Nerve³ 

• Location: Identified as an anatomical variation branching from the inferior alveolar nerve, the retromolar nerve traverses the retromolar canal and may extend toward the buccal gingiva near the third molar region. 

• Risk: Though not always present, when it exists, surgical trauma during flap elevation or bone removal in the retromolar area can lead to sensory disturbances in the posterior buccal mucosa. 

• Tip: Preoperative CBCT imaging is recommended to detect the presence of a retromolar canal. Awareness of this variation helps prevent inadvertent nerve injury during third molar disimpaction. 

4. Maxillary Artery and Pterygoid Venous Plexus⁴ 

• Location: Located within the infratemporal fossa, posterior to the maxilla and adjacent to the lateral pterygoid muscle. These structures lie near the path of displaced maxillary third molars. 

• Risk: Retrieval attempts involving deep or posterior dissection may injure these vascular structures, leading to significant hemorrhage and increased morbidity. 

• Tip: Prevent further displacement by placing a finger or periosteal elevator posterior to the tooth. Avoid blind instrumentation and ensure proper imaging and surgical planning to minimize vascular trauma.  

5. Submandibular Gland and Duct 

• Location: Positioned medial to the mandible, in close proximity to the lingual and hypoglossal nerves within the floor of the mouth⁵. 

• Risk: Surgical trauma can result in salivary fistula, ductal obstruction, or gland dysfunction, especially during submandibular gland excision or stone retrieval. 

• Tip: Dissect laterally and cautiously in the absence of gland pathology. Preserve the duct and surrounding neurovascular structures to minimize postoperative complications. 

Radiographic Planning: Your Anatomical Map  

Radiographs are indispensable in mapping out these structures. Panoramic imaging offers a broad view, but Cone Beam CT (CBCT) provides precise 3D localization of the IAN and root morphology.  

Preventing Complications: Surgical Wisdom 

• Preoperative Assessment: Evaluate patient history, imaging, and anatomical variations. 

• Flap Design: Choose incisions that preserve nerve integrity and allow adequate access. 

• Bone Removal: Use controlled techniques to avoid excessive trauma. 

• Tooth Sectioning: Reduces force and risk to adjacent structures. 

• Postoperative Care: Monitor for signs of nerve injury, bleeding, or infection.  

Final Takeaway 

Mastery of anatomical knowledge is the cornerstone of safe and effective third molar disimpaction. By respecting the structures that lie hidden beneath the mucosa and bone, practitioners can minimize complications and elevate their surgical outcomes. Let anatomy be your guide—not your obstacle. 

Reference: 

1. Muhsin H, Brizuela M. Oral surgery, extraction of mandibular third molars. InStatPearls [Internet] 2023 Mar 19. StatPearls Publishing. 

2. Ngeow WC, Tay HW, Sarna K, Cheah CW, Raj M, Acharya SK, Koo ZZ, Wey MC. Challenges in Diagnosing the Course of the Lingual Nerve for Clinical Practice and Research. Diagnostics. 2025 Jun 25;15(13):1609. 

3. Tahmasebi M, Heidarkhan Tehrani S, Mehmani F, Mesgari H, Mehdizadeh A. Anatomical Correlation Between Mandibular Third Molar Position and Retromolar Nerve Variations: A CBCT Study. Journal of Research in Dental and Maxillofacial Sciences. 2025 Jun 10;10(2):159-67. 

4. Sharmila GS. Techniques of retrieval of displaced maxillary 3rd molar from infratemporal fossa. MAR Dental Sciences & Oral Rehabilitation. 2023;4(8):4–12. 

5. Beşer CG, Erçakmak B, Ilgaz HB, Vatansever A, Sargon MF. Revisiting the relationship between the submandibular duct, lingual nerve and hypoglossal nerve. Folia Morphologica. 2018;77(3):521-6.