Table 2.

Characteristics of study participants.

Study Number	Number of Individuals	Study Groups	Age (Years)	Sex (Male)
Alvim-Pereira et al. [21]	207	137 with dental implants vs. 70 without implants	51.6 years vs. 52.8 years	36.5% with implants vs. 40.0% without
Flanagan et al. [22]	1	NR	34 years	1 Male
Bryce et al. [23]	1	NR	29 years	1 Male
Fretwurst et al. [24]	2	NR	48 years vs. 51 years	2 Male
Mangano et al. [25]	885	850 successful implants vs. 35 early failures	57.3 years	51.5%
Pereira et al. [26]	244	81 with Vitamin D receptor mutation vs. 163 controls	51.9 years	33.6%
Kwiatek et al. [27]	122	Group 1: Vitamin D < 30 ng/mL, Group 2: Vitamin D < 30 ng/mL + supplement, Group 3: Vitamin D > 30 ng/mL	43.8 years	46.7%

NR—not reported.