Hypoxia-Inducible Factor-1α: A Potential Factor for the Enhancement of Osseointegration between Dental Implants and Tissue-Engineered Bone

Bell’s palsy is a sudden unilateral paralysis of the facial nerve. Postoperative Bell’s palsy following surgery is rare. It occurs in less than 1% of operations. The hypothesis: We premise that the main cause of immediate postoperative Bell's palsy is latent herpes viruses (herpes simplex virus type 1 and herpes zoster virus), which are reactivated from cranial nerve ganglia. Inflammation of the nerve initially results in a reversible neurapraxia, but ultimately Wallerian degeneration ensues. The palsy is often sudden in onset and evolves rapidly, with maximal facial weakness developing within two days. Associated symptoms often seen in idiopathic Bell’s palsy are tearing problems, hyperacusis and altered taste.Evaluation of the hypothesis: Facial paralysis presenting postoperatively is distressing and poses a diagnostic challenge. A complete interruption of the facial nerve at the stylomastoid foramen paralyzes all the muscles of facial expression. Taste sensation may be lost unilaterally and hyeracusis may be present. Idiopathic Bell’s palsy is due to inflammation of the facial nerve in the facial canal. Bell’s palsy may also occur from lesions that invade the temporal bone (carotid body, cholesteatoma, dermoid cyst, acoustic neuromas). Although traumatic Bell’s palsy cannot be ruled out, it seems logic to postulate that the main cause of immediate postoperative Bell's palsy is latent herpes viruses.