Table 2.

Association between extraction time and difficulty indices of impacted third molars

Grade	n	Extraction time (min)	P-value		Correlation coefficient (r)
Difficulty index
I	17	12.18±5.39	<0.0011	0.0012 (I vs II) <0.0012 (II vs III)	0.599
II	45	18.28±5.34
III	6	28.20±5.17
Half-up difficulty index
1	13	10.60±4.33	<0.0011	0.3182 (1 vs 1.5) >0.9992 (1.5 vs 2) <0.0012 (2 vs 2.5) >0.9992 (2.5 vs 3.5) NA (2.5 vs 3) NA (3 vs 3.5)	0.728
1.5	4	16.30±7.33
2	30	15.38±4.06
2.5	15	24.08±3.23
3	1	31.60
3.5	5	27.36±0.33
One-up difficult index
I	13	10.60±4.33	<0.0011	0.0102 (I vs II) <0.0012 (II vs III) >0.9992 (III vs IV)	0.764
II	34	15.44±4.28
III	16	24.38±3.49
IV	5	27.36±5.33

(NA: not available)

¹One-way ANOVA. ²Post hoc test with Bonferroni correction.

Values are presented as mean±standard deviation.