Table 2.

Safety analysis of the studies grouped by bristle characteristics

Groups	Reference	Description of bristle end-shape/stiffness	Conclusion
Bristle stiffness	Zimmer et al.19	Hard vs. medium vs. soft (all TP)	More gingival lesions are shown from hard toothbrushes in comparison to soft and medium toothbrushes (P < 0.01) after 4 and 8 weeks. No significant differences between medium and soft groups
	Sgan-Cohen et al.28	Medium vs. soft (both ER)	Over 4 weeks, no AE were reported
Bristle end-shape	Checchi et al.29	TP vs. ER (both soft)	The majority of gingival recessions remained stable over 6 months. However, a slight gingival recession width reduction was observed in the TP group, and an increase in gingival recession width observed in the ER group
	Mankodi et al.30	TP vs. ER (both soft)	No AE reported over 4 weeks
	Nathoo et al.31	TP vs. ER (both soft)	No AE reported over 4 weeks
	Sgan-Cohen et al.32	TP vs. ER (both soft)	No AE reported over 2 months
	Versteeg et al.33	TP vs. ER (both soft)	There was an inclination toward fewer sites with gingival abrasion with the use of an ER toothbrush in comparison to a TP toothbrush over 4 weeks
	Gallob et al.34	TP vs. ER (both soft)	One AE related to product usage was reported with the TP toothbrush. The AE was not specified
Bristle stiffness and bristle end-shape	Harpenau et al.36	Extra-soft and TP vs. soft and ER	No AE reported over 5 weeks
	Sgan-Cohen et al.37	Extra-soft and TP vs. soft and ER	No AE reported over 8 weeks
	Sharma et al. Study 138	Soft and TP vs. soft and ER	No AE reported over 12 weeks
	Ren et al.39	Extra-soft and TP vs. soft and TP/ER vs. soft and ER	No AE reported over 4 weeks
	Rösing et al.35	Soft and TP vs. extra-soft and ER	Tooth sensitivity was reported with the soft and TP toothbrushes. Burning sensation, gingival sensitivity, gingival bleeding and aphthae development were reported with the extra-soft and ER toothbrushes

AE, adverse event; ER, end-rounded; TP, tapered.