Table 3. Univariate and multiple regression analysis of the association between DMFT index and independent variables using the negative binomial with log-link function in Generalized Linear Models (n = 2799).

Variables	Categories	IRR *	p-value		IRR *	p-value
Gastroesophageal reflux disease
	Yes	1.01 (0.93–1.09)	0.89
	No	1
Frequency of regurgitation
	Once or more/week	1.04 (0.85–1.28)	0.68
	2–3 times/month	1.00 (0.90–1.12)	0.98
	No	1
Gender
	Female	0.96 (0.89–1.04)	0.30
	Male	1
Age at interview €
	35–45	0.74 (0.53–1.05)	0.09		0.01 (0.00–0.09)	≤0.001
	46–55	0.87 (0.62–1.23)	0.44		0.12 (0.02–0.82)	0.03
	56–65	0.99 (0.70–1.42)	0.98		1.06 (0.14–7.97)	0.96
	≥66	1			1
Wealth score index
	Very poor	1.07 (0.95–1.22)	0.26
	Poor	1.05 (0.91–1.20)	0.51
	Moderate	1.01 (0.90–1.13)	0.90
	Good	0.98 (0.88–1.08)	0.68
	Very good	1
Years of education €
	0–8	1.10 (1.02–1.18)	0.02
	≥9	1
Tobacco use €
	Yes	1.12 (0.99–1.26)	0.06
	No	1
Alcohol drinking
	Yes	1.07 (0.82–1.41)	0.60
	No	1
Toothbrushing €
	<1/day	5.04 (3.19–7.97)	≤0.001		4.43 (2.85–6.90)	≤0.001
	≥1/day	1			1
Sweet foods
(Free sugars: gr/day)	>23.91	0.82 (0.47–1.43)	0.49
	10.35–23.90	0.75 (0.43–1.31)	0.31
	≤10.34	1
Sweet beverages
(Free sugars: gr/day)	≥62.09	1.26 (0.73–2.17)	0.41
	18.94–62.08	0.88 (0.51–1.53)	0.65
	≤18.93	1
Natural fruit juice
(Free sugars: gr/day)	≥7.563	0.73 (0.43–1.23)	0.23
	0.001–7.562	0.93 (0.52–1.65)	0.80
	≤0.000	1
Body Mass Index (kg/m 2 )
	≥25	0.99 (0.90–1.09)	0.83
	<18.5	1.11 (0.63–1.95)	0.72
	18.5–24.9	1

*Incidence Rate Ratio

^€ Entered in the multiple regression analysis