Intraoperative aetiological factor Indirect or direct; mechanism Postoperative aetiological factor Indirect; mechanism
Traumatic local anaesthesia
Chemical (cytotoxic) injury by local anaesthetic Indirect; endoneurial oedema, compression and secondary ischemia Direct; IAN degeneration Injection needle trauma to epineurial blood vessels or inferior alveolar artery Indirect; hematoma with reactive fibrosis and scar formation, compression and secondary ischemia
Injection needle Direct; transection of multiple IAN fibres and entire fascicles
Implant drill
Partial intrusion into MC Indirect; hematoma and secondary ischemia Thermal injury Indirect; inflammation of bone and IAN with secondary ischemia
Full intrusion into MC Direct; mechanical trauma - encroach, transection, or laceration and/or compression and primary ischemia of IAN
Chemical (cytotoxic) injury by irrigation solution Direct; IAN degeneration
Thermal injury Direct; IAN degeneration
Dental implant
Partial intrusion into MC Indirect; hematoma or/and deposition of debris, compression and secondary ischemia Infection Indirect; inflammation of bone and IAN with secondary ischemia
Implant is too close to MC Indirect; bone and IAN stress, compression with secondary ischemia
Full intrusion into MC Direct; mechanical trauma - encroach, transection, or laceration and/or compression and primary ischemia of IAN
Chronic stimulation Indirect; implant is situated aside of or on top of the nerve with chronic neuropathy formation
Wrong operation technique
Scalpel Direct; mental nerve injury or transection Soft tissue swelling Indirect; mental nerve compression caused by soft tissue oedema
Soft tissue reflection and retraction Direct; mental nerve injury caused by reflection, retraction and pressure
Soft tissue suturing Direct; mental nerve compression caused by suture material