Before 6-month
postoperative
P significancea
Mean (SD) Mean (SD)
Vertical distal 13.6 (2.3) 10.1 (3.4) < 0.05
Vertical central 20.7 (3.4) 12.5 (2.8) < 0.05
Vertical mesial 12.7 (2.8) 8.8 (2.5) < 0.05

aStatistically significant at the level P < 0.05, Pearson’s Chi-squared test.
SD = standard deviation.