Table 4.

The impact of oral hygiene habits on risk of developing head and neck squamous cell carcinoma.

References	Year	Rated Factor	Type of Study	n	Risk of HNC	Description
Pereira et al. [36].	2020	flossing (flossing regularly vs. flossing sometimes)	case-control study	899 cases 899 controls	Decreased (in the group flossing regularly)	OR = 0.16; 95% CI: 0.08—0.33
Gupta et al. [37].	2020	Tooth brushing (<2 times/day vs ≥2 times/day)	case-control study	212 cases 188 controls	Increased (in the group brushing teeth <2 times/day)	OR = 2.09 95% CI: 1.27—3.45)
Kawakita et al. [38].	2017	Tooth brushing (<2 times/day)	case-control study	484 cases 313 controls	Increased	OR = 1.77; 95% CI: 1.46—2.15
Chen et al. [44].	2016	Tooth brushing (≥2 times/day vs <2 times/day)	case-control study	250 cases 996 controls	Decreased (in the group brushing teeth ≥2 times/day)	OR = 0.50; 95% CI: 0.25—0.98
Hashim et al. [35].	2016	Tooth brushing (≥1/day vs. <1/day)	case-control study	7 411 cases 10 333 controls	Decreased (in the group brushing teeth ≥1 times/day)	OR = 0.83; 95% CI: 0.68— 1.00
Tsai et al. [45].	2014	Tooth brushing (<2 times/day vs ≥2 times/day)	case-control study	436 cases 514 controls	Increased (in the group brushing teeth <2 times/day)	OR = 1.40; 95% CI: 1.02—1.91
Chang et al. [33].	2013	Tooth brushing (<2 times/day vs ≥2 times/day)	case-control study	317 cases 296 controls	Increased (in the group brushing teeth <2 times/day)	OR = 1.5; 95% CI: 1.02—2.23
Sato et al. [46].	2011	Tooth brushing (never vs. ≥2 times/day)	case-control study	469 cases 2696 controls	Increased (in the group never brushing teeth)	OR = 2.86; 95% CI: 1.07—7.66
Wu et al. [47].	2017	Tooth brushing (<2 times/day)	case-control study	242 cases 856 controls	Increased	OR = 1.50 95% CI: 1.08—2.09

OR—odds ratio, CI—confidence intervals; HNC—head and neck squamous cell carcinoma.