Table 2. Frequency of patients by matched risk factors for alveolar osteitis, distributed by treatment group.

Risk factor	Chlorhexidine (n=372)	Placebo (n=372)	Total (n=744)
S	24	24	48
PI	191	190	381
TE	3	3	6
S+PI	106	107	213
S+TE	6	6	12
PI+TE	26	26	52
S+PI+TE	16	16	32
Total	372	372	744

S: Tobacco smoke

PI: Previous infection in surgical site

TE: Traumatic extraction