Table 1.

Elements abstracted from searched studies

Study	Elements
All studies	Citation and publication status
	Study design: cross sectional or cohort study
	Participants: number, sex, age range, country, residency and representativeness
	Focal factor(s) with respect to the association with tooth loss: smoking only or various factors including smoking
	Factors entered in the final analytical model
	Type of the estimate of association, effect size and confidence interval
	Category of evaluated group: age group, sex and type of exposure
	Statistical significance of the dose-response relationship
	Special mention: sensitivity, subgroup and other types of analyses and the source of funding
Cross sectional studies	Definition and prevalence of tooth loss
Cohort studies	Observational length and non-respondent and follow-up rates