·We selected patients with unilateral inferior alveolar nerve (IAN) injury for more than one month caused by mandibular third molar extraction who went to the outpatient department of oral surgery of the Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine from July 2018 to January 2021. All patients were followed up regularly, and the visual analog scale (VAS) was used to determine the degree of numbness recovery. During the follow-up, if the patient's VAS<3, it was determined that the patients recovered from numbness and were included in the recovery group. The follow-up ended. If the follow-up time was more than 1 year, and the patients' VAS≥3, it was judged that the patients' numbness didn't recover and they were included in the unrecovered group. We performed current perception threshold (CPT), electrical pulp test (EPT) and two-point discrimination (2PD) on patients of different groups, and compared the values of the three tests on the healthy side and the correlation with prognosis.

·A total of 60 patients were included in this study, including 14 males and 46 females. At the end of follow-up, 44 patients had VAS<3, and were setted as recovery group. The average recovery time was (4.1±1.4) months. The remaining 16 patients did not have VAS<3, and were setted as the non-recovery group. The differences of two sides of all patients' CPT, EPT and 2PD were statistically significant (all P<0.05). For the data of affected side of patients with and without lower lip sensation recovery, only CPT 5 Hz and EPT were significantly different (both P=0.000). CPT (5 Hz) had high sensitivity (93.8%) and specificity (87.5%) in the evaluation of prognosis. Similarly, EPT also had high sensitivity (93.8%) and specificity (93.8%). The CPT (5 Hz) of the affected side was consistent with the value of EPT of the posterior teeth.

·CPT, EPT and 2PD can evaluate the injury of inferior alveolar nerve. The value measured at CPT 5 Hz and posterior tooth EPT can evaluate the prognosis of nerve recovery.