Table 3.

Probing depth gains between ages 26 and 32, periodontal status at age 26, and earlier smoking exposure, by summary smoking exposure category

	Smoking exposure group					All combined
	smoked at all ages	other age-32 smokers	gave up after 26	other ex-smokers	never smoked
Probing depth gains between ages 26 and 32
Number showing PD gain of 2+ mm (%)	52 (54.7)	63 (39.4)	30 (43.5)	41 (56.9)	195 (47.1)	381 (47.0)
Number showing PD gain of 3+ mm (%)	9 (9.5)	14 (8.8)	2 (2.9)	2 (2.8)	17 (4.1)	44 (5.4)*
Mean % of sites showing PD gain of 2+ mm (SD)	3.2 (4.8)	2.0 (3.4)	1.7 (2.3)	2.9 (3.6)	2.4 (4.2)	2.4 (4.0)
Mean % of sites showing PD gain of 3+ mm (SD)	0.4 (2.0)	0.2 (0.8)	0.1 (0.4)	0.1 (0.4)	0.2 (1.5)	0.2 (1.3)
Periodontal disease measures at age 26
No. with 1+ sites with 4+ mm AL	33 (34.7)	35 (21.9)	9 (13.0)	14 (19.4)	56 (13.5)*	147 (18.1)
No. with 1+ sites with 5+ mm AL	8 (8.4)	7 (4.4)	1 (1.4)	4 (5.6)	8 (1.9)*	28 (3.5)
Mean % of 1+ sites with 4+ mm AL (SD)	2.5 (5.2)	1.4 (4.1)	0.4 (4.8)	1.0 (2.5)	0.7 (2.6)*	1.0 (3.3)
Earlier smoking exposure
Mean pack-years (SD) up to age 21	5.2 (2.3)	2.8 (2.3)	2.6 (2.2)	1.3 (1.6)	0.0 (0.0)†	1.5 (2.3)
Mean pack-years (SD) from age 21–26	4.1 (1.7)	3.3 (1.9)	2.6 (2.2)	0.6 (0.9)	0.0 (0.0)‡	1.4 (2.0)

^*p<0.05.

^†p<0.05; oneway ANOVA: those who gave up smoking after age 26 differ from all other groups except for the other age-32 smokers.

^‡p<0.05; oneway ANOVA: those who gave up smoking after age 26 differ from all other groups.

PD, probing depth.