Fig. 1

Flowchart of participants eligible at 3 years of age in the present retrospective study

Experimental groups: EPT, extremely preterm–born (n = 33); VPT, very preterm–born (n = 122); Control group: FT, full term–born (n = 156)

* Identified through the Swedish Medical Birth Register

** Identified through dental clinics

Not reachable = No response to mailed written information

Declined = Declined participation for reasons unknown

Excluded = Dental records were not available throughout for ages 3–19 years