Group C1 Control group

Group C2

(1.5% ZrO₂(

Group C3

(3% ZrO₂(

Group C4

(5% ZrO₂(

Group C5

(7% ZrO₂(

P-value

Mean

SD

Mean

SD

Mean

SD

Mean

SD

Mean

SD

15.95^c

0.96

17.35^c

0.63

19.10^b

1.07

20.60^b

0.56

23.19^a

1.05

0.000^*