Maxillary third molar extraction requires effective pain control. Local anesthesia is the standard method, temporarily blocking sensory signals from reaching the brain. The objective is to achieve profound numbness throughout the tooth structure and surrounding soft tissues before the procedure. This is achieved by injecting an anesthetic solution near the specific nerves that innervate the surgical site. Successful extraction relies on precisely targeting the nerve branches responsible for sensation in the upper jaw’s posterior region.
The Primary Nerve Supply for Maxillary Molars
The main sensory pathway for the maxillary second and third molars is the Posterior Superior Alveolar (PSA) nerve. The PSA nerve is a branch of the maxillary division of the trigeminal nerve (Cranial Nerve V). It provides sensation to the internal dental pulp, the dentin, and the bony structure surrounding the roots of these molars.
The nerve descends along the back wall of the maxilla before entering small canals in the bone to reach the teeth. It is the primary target for anesthetizing the tooth itself, preventing the patient from feeling manipulation or removal. The PSA nerve typically supplies the second and third molars completely, along with two roots of the first molar. Blocking this single nerve branch successfully numbs the entire tooth.
Ensuring Complete Pain Control: Secondary Nerves
While the PSA nerve handles deep tooth and bone sensation, extraction involves manipulating soft tissues supplied by different nerves. Complete pain control requires anesthetizing the gums on both the cheek-side and the palate-side of the extraction site. The soft tissue on the roof of the mouth (palatal gingiva) is innervated by the Greater Palatine nerve.
The Greater Palatine nerve emerges onto the palate, providing sensation to the posterior hard palate up to the midline. Blocking this nerve prevents sharp pain when the palatal tissue is handled during the extraction. The soft tissue on the cheek-side (buccal gingiva) is largely covered by the PSA nerve. However, the Buccal nerve sometimes provides sensation to the soft tissues near the upper third molar.
A third accessory nerve, the Middle Superior Alveolar (MSA) nerve, is sometimes targeted, though less often for the third molar. The MSA nerve typically supplies the first and second premolars. Due to anatomical variations, it can sometimes contribute to the sensation of the mesial root of the first molar. While it does not directly supply the third molar, its field may require supplementary anesthesia if the PSA block is not fully effective.
The Injection Procedure: Targeting the Nerves
The primary injection technique used to anesthetize the PSA nerve is the Posterior Superior Alveolar block (tuberosity block). The needle is inserted high into the cheek-side fold of tissue above the second molar. The injection is directed upward, inward, and backward to deposit the anesthetic solution near the nerve trunk before it enters the bone.
The insertion depth is typically around 16 millimeters in an adult, allowing the solution to reach the nerve as it descends toward the teeth. A volume of 1.0 to 1.5 milliliters of anesthetic solution is deposited slowly to maximize diffusion and minimize discomfort. This approach effectively numbs the tooth’s pulpal tissue and the cheek-side gums with a single injection.
The second procedure, the Greater Palatine block, is necessary to numb the palatal soft tissue. The injection site is near the greater palatine foramen, typically found between the second and third molars. This location is close to the junction of the hard palate and the alveolar bone. The dentist first applies topical anesthetic and pressure to prepare the sensitive palatal tissue.
The needle is inserted perpendicular to the palatal tissue. A small volume (approximately 0.5 milliliters) is administered slowly to avoid discomfort. The goal is to flood the area around the nerve as it exits the foramen. Performing both the Posterior Superior Alveolar block and the Greater Palatine block ensures the entire surgical site is numb for the extraction.