Table 1.

Inclusion and exclusion criteria of study participants.

Inclusion criteria	Participants who are Chinese and aged 18 or older
	Participants who are able to give consent
	Participants who have 5 or more anterior teeth
	Participants who have adequate mouth opening for visualisation of at least 3 mm gingival tissue from maxillary and mandibular gingival margins
	Participants who are able to attend dental appointment and hold still during taking intraoral photograph
Exclusion criteria	Participants who have non-plaque-related oral mucosal diseases that preclude the use of mirror retractors