Table 1 Univariate analysis of risk factors of osteoradionecrosis

V10

<14.5 ml

31

26.1

≥14.5 ml

32

0.015

53

V20

<11.9 ml

31

20

≥11.9 ml

32

0.001

58.5

V30

<8.1 ml

31

13.7

≥8.1 ml

32

0.001

64.4

V40

<4.6 ml

31

12.1

≥4.6 ml

32

0.0002

67.7

V50

<3.0 ml

31

11.7

≥3.0 ml

32

0.0002

69.5

Age (years)

<59

31

33.5

≥59

32

0.23

45.5

Sex

Male

31

40.4

Female

32

0.5

38.2

Teeth in the PTV

None

34

5.9

Some

29

0.0001

81

Smoking

Yes

22

41.6

No

41

0.66

38.6

Alcohol

Yes

31

48.6

No

32

0.11

30.3

Chemotherapy

Yes

23

54.0

No

40

0.04

30.5