Exclusion criteria were the following:~lower third molar buds;~lack of contiguous second molar;~wide cyst-like areas or severe osteo-metabolic/tumor pathologies associated with the lower third molar;~pre-operative neurosensory deficit related to IAN on the side where surgery was to be performed.~Clinical and radiographic data were noted on a special chart, developed in four areas concerning the patient's personal data, pre-operative case evaluation, surgical technique, and post-operative course.~Assessment of surgical difficulty was reached using a modified Pederson's scale by assigning a 1 to 3 score to each of the following variables: tooth inclination (mesioangular/vertical = 1; horizontal = 2; distoangular = 3), depth of impaction (modified Winter classification: A/B = 1; C1 = 2; C 2= 3), Pell & Gregory class (I = 1; II = 2; III = 3), root morphology (fused or slightly divergent = 1; strongly divergent = 2; presence of apical anomalies = 3), proximity to the IAN (none = 1; contiguity = 2; embrication = 3) and maximum mouth opening (> 4 cm = 1; 3-4 cm = 2; < 3 cm = 3). For each extracted third molar, a total score between 6 and 18 was therefore obtained.~All surgeries were performed by the same expert surgeon (RP), with the buccal approach using local anesthesia, and included the following maneuvers:~luxation of the coronal portion of the tooth/root in an ipsilateral or parallel direction with respect to the IAN position and running, in order to minimize nerve compression;~post-extraction residual bone cavity inspection using a Zeiss 4x300 magnification optical system to better identify intra-operative nerve exposure.~No material was inserted into the residual cavity, neither by regeneration nor by haemostasis.~After one week, sensitivity was tested on both sides with the tactile test using a 27-gauge needle tip and, if a difference was found, the patient was followed up once a week for the first month and every two weeks thereafter, until he/she reported to perceive the pin-prick test in the affected side the same way as the healthy side.
Objective The present study aimed to evaluate which factors were statistically associated with a greater probability of inferior alveolar nerve (IAN) damage during lower third molar surgery.~Study Design A prospective observational study was performed at the Oral Surgery Unit of the Umberto I Hospital on 92 patients which underwent surgical extraction of a lower third molar, that was radiographically overlapped to the mandibular canal. All surgeries were performed by the same expert surgeon. A principal component analysis and the exact two-tailed Fisher test were used.