77.因口腔周圍接受放射線治療造成的味覺喪失，其全部恢復期至少需時多久？
(A)1個月
(B)2～4個月
(C)6～9個月
(D)一年以上

Taste buds are sensitive to radiation. Doses in the therapeutic range cause extensive degeneration of the normal histologic architecture of taste buds. Patients often notice a loss of taste acuity during the second or third week of radiotherapy. Bitter and acid flavors are more severely affected when the posterior two thirds of the tongue is irradiated and salt and sweet when the anterior third of the tongue is irradiated. Taste acuity usually decreases by a factor of 1000 to 10,000 during the course of radiotherapy. Alterations in the saliva may partly account for this reduction, which may proceed to a state of virtual insensitivity. Taste loss is reversible and recovery takes 60 to 120 days.
 oral radiology principles and interpretation, 6th edition, p.23