A case report of a long-term abandoned torn lingual nerve injury repaired by collagen nerve graft induced by lower third molar extraction

BACKGROUND: The lingual nerve plays an important role in multiple functions, including gustatory sensation and contact sensitivity and thermosensitivity. Misdiagnosed conservative treatments for serious lingual nerve (LN) injuries can induce the patient to serious mental disability. After continuous observation and critical diagnosis of the injury, in cases involving significant disruption of lingual nerve function, microneurosurgical reconstruction of the nerve is recommended. Direct anastomosis of the torn nerve ends without tension is the recommended approach. However, in cases that present significant gaps between the injured nerve ends, nerve grafts or conduits (tubes of various materials) are employed. Recently, various reconstruction materials for peripheral nerves were commercially offered especially in the USA, but the best method and material is still unclear in the world. There currently exists no conventional protocol for managing LN neurosensory deficiency in regard to optimal methods and the timing for surgical repair. In Japan, the allograft collagen nerve for peripheral nerves reconstruction was permitted in 2017, and we tried to use this allograft nerve and got a recommendable result. CASE PRESENTATION: This report is a long-term abandoned torn LN reconstructed with allograft nerve induced by the lower third molar extraction. CONCLUSIONS: In early sick period, with the exact diagnosis, the LN disturbance should be managed. In a serious condition, the reconstruction with allograft nerve is one of the recommendable methods.