Table 3.

Background characteristics and data collection from the other design studies

Reference	Region	Time frame of study	Design of study	Gender	Age, years (average, mean with standard deviation or range)	Cancer outcome with subsite	Case definition	No of Cases	Sample population	Frequency of dental visits	Quality assessment
Bertl et al. [31]	Austria	2013	Cross-sectional	M + F	> 18	HNCs (oral cavity, nasopharynx, oropharynx, hypopharynx, or larynx)	Patients from outpatient cancer clinics	48	Tertiary hospital	< 12 months or ≥ 12 months	Moderate
Langevin et al. [4]	Greater-Boston	2006–2011	Case-series	M + F	≥ 18	OCs (tongue, salivary gland, gum, mouth), oropharynx and hypopharynx	Incident cases	441	Teaching hospital	At least annual, infrequent, rare or never	Strong
Frydrych et al.[53]	Western Australia	2005–2009	Retrospective observational study of medical records	M + F	Average age for M = 59 and for F = 60	OCs (lip, tongue, gum, mouth, palate) tonsil and oropharynx	Incident cases	127	Teaching hospital	Time (months) since the patient’s last dental visit and regularity of attending dental appointments	Moderate
Watson et al. [1]	Florida	NG	Cross-sectional	M + F	60 (13.2)	OCs (lip, oral cavity) or oropharynx	Incident cases	131	Two tertiary care centres	Within preceding 12 months, more than 12 months ago	Moderate
Lockhart et al. [38]	United States	NG	Screening	M + F	17–86	HNCs (not defined)	NG	131	HNC clinic	Emergency dental care, annually, regularly or twice yearly	Weak
Gellrich et al. [32]	Europe	NG	Retrospective observational study of medical records	M + F	Average age of M = 58.2, F = 62.6	OCs (floor of the mouth, tongue, gingiva, non-specified sites for oral cancer, excluding lip)	Incident cases	1543	Oral and maxillofacial surgery departments	Quarterly, annually, twice a year, every 2 years, less than every 2 years	Weak