According to our predefined quality assessment criteria, all of 97 included trials were evaluated as having unclear risk of bias (Table 2, Figure 3 ). None of the 97 trials reported sample size calculation. Eleven trials described randomization procedures, nine trials [9-11, 20, 30, 38-41] used a random number table, one drew lots [19] , and one trial separated patients by odd and even number of patient ID as a quasirandomization [42] . Only one trial [43] blinded both patients and outcome assessors, and three trials [44] [45] [46] blinded patients. None of the trials reported adequate allocation concealment. Five out of ninety seven trials mentioned that followup ranged from 3 months to 12 months after treatment. One trial [47] followed all the patients for 12 months, one trail [38] for 6 month, and the rest [9, 11, 12] for 3 months. However, neither of them used intention to treat method.