Table 2.

DMFS outcome data at baseline and change in DMFS during the follow-up period for each tobacco group and residential-area household purchasing power group, with p-values for the tobacco group comparisons of change in DMFS

% low household purchasing power	Tobacco group	DMFS baseline 16 years				Change in DMFS, 16–19 years
		N	Mean	SiC*	CF†	N	ΔMean	ΔSiC	ΔDMFS>0%‡	p-value§
< 10	Ever users	152	2.5	7.6	41.4	152	1.3	4.2	43.4	0.02
	Never users	1553	1.7	6.5	49.8	1553	0.9	3.7	34.8
10-19.9	Ever users	382	3.3	7.3	30.1	382	1.6	4.2	51.8	< 0.001
	Never users	2295	2.4	6.8	38.1	2295	1.0	3.8	38.2
20-29.9	Ever users	755	3.9	8.0	27.3	755	1.8	4.6	56.7	< 0.001
	Never users	3826	3.0	7.8	35.8	3826	1.5	4.4	43.0
30+	Ever users	162	4.4	8.9	27.8	162	2.3	5.0	59.3	< 0.001
	Never users	892	3.7	8.8	32.2	892	1.5	4.6	46.0

* Significant caries index based on DMFS.

† Proportion caries-free.

‡ Proportion with new caries during the observation period (16–19 years).

§ P-value from the Wilcoxon-Mann–Whitney test comparing the distributions of DMFS between ever vs. never users.

The overall p-value < 0.0001 (stratified Wilcoxon-Mann–Whitney test).