Table 2. The effect size across included studies.

Study	Year	exposure to waterfluoridation	RRs/HRs/ORs (95%CIs)
Simonen O	1985	1.0 vs. 0–0.1mg/l
		female	1.5(1.2 to 1.8)
		male	2.5(1.6 to 3.9)
Sowers MF	1991	4.0±0.1 vs. 1.0 mg/l	2.2(1.1 to 4.7)
Danielson C	1992	1.0 vs. 0.3ppm
		female	1.27(1.08 to 1.46)
		male	1.41(1.0 to 1.81)
Jacobsen SJ	1992	nonfluoradated vs. fluoridated
		female	1.17(1.13 to 1.22)
		male	1.08(1.06 to 1.1)
Jacobsen SJ	1993	nonfluoradated vs. fluoridated
		male	0.78(0.37 to 1.66)
		female	0.6(0.42 to 0.85)
Cauley JA	1995	1.01±0.21 vs. 0.15±0.10 mg/l
		0 year	1.0
		1–10 years	0.89(0.42 to 1.92)
		11–20years	0.58(0.14 to 2.48)
		>20 years	0.44(0.1 to 1.86)
Karagas MR	1996	nonfluoradated vs. fluoridated
		male	1(0.92 to 1.09)
		female	1.01(0.96 to 1.06)
Lehmann R	1998	0.77–1.20 vs. 0.08–0.36mg/l
		male
		60–64 years	2.14(0.89 to 5.2)
		65–69 years	0.55(0.22 to 1.39)
		70–74 years	0.78(0.27 to 1.39)
		75–79 years	1.05(0.65 to 1.69)
		80–84 years	1.02(0.67 to 1.55)
		≥80 years	1.92(1.07 to 3.45)
		female
		60–64 years	0.9(0.51 to 1.58)
		65–69 years	1.56(1 to 2.44)
		70–74 years	1.09(0.76 to 1.57)
		75–79 years	1.38(1.06 to 1.8)
		80–84 years	1.2(0.95 to 1.52)
		≥80 years	1.41(1.1 to 1.81)
Kurttio P	1999	female
		≤0.10 mg/l	1.0
		0.11–0.30 mg/l	0.93(0.84 to 1.02)
		0.31–0.50 mg/l	1.12(0.93 to 1.34)
		0.51–1.00 mg/l	1.12(0.96 to 1.31)
		1.10–1.50 mg/l	1.08(0.88 to 1.32)
		>1.50 mg/l	1.08(0.8 to 1.46)
		male
		≤0.10 mg/l	1.0
		0.11–0.30 mg/l	1.05(0.9 to 1.22)
		0.31–0.50 mg/l	0.72(0.51 to 1.02)
		0.51–1.00 mg/l	1.03(0.81 to 1.32)
		1.10–1.50 mg/l	0.67(0.46 to 0.97)
		>1.50 mg/l	0.98(0.61 to 1.6)
Phipps KR	2000	mixed exposure	0.73(0.49 to 1.09)
		continuous exposure	0.69(0.5 to 0.96)
Hillier S	2000	≥0.9 vs. <0.9mg/l	1(0.7 to 1.5)
Li Y	2001	0.25–0.34 mg/l	0.99(0.21 to 4.77)
		0.58–0.73 mg/l	1.12(0.35 to 3.62)
		1.00–1.06 mg/l	1.0
		1.45–2.19 mg/l	2.13(0.76 to 5.96)
		2.62–3.56 mg/l	1.73(0.56 to 5.33)
		4.32–7.97 mg/l	3.26(1.20 to 8.82)
Park EY	2008	fluoridated vs. nonfluoradated
		female	0.88(0.77 to 1)
		male	0.91(0.84 to 0.99)
Näsman P	2013	Very low <0.3	1.0
		Low 0.3–0.69	0.97(0.94 to 0.99)
		Mendium 0.7–1.49	0.97(0.94 to 1)
		High ≥1.5	0.98(0.93 to 1.04)