The new site, in Cornwall, will open by the summer.
Resonance, which helps organisations to become investment ready and to raise funding, advised Smile Together on the investment.
Smile Together – formed in 2016, and shortlisted in last year's UK Social Enterprise Awards – secured the investment from BII in late 2018, in the form of an unsecured eight-year fixed interest loan, with capital repayments not starting until year four.
The investment will finance the refurbishment of a former grammar school, which the community interest company (CIC) has purchased itself, into a purpose-built dental centre designed and adapted for patients with special needs, including mental health conditions and autism. The new site will increase local access to competitively-priced and fully accessible dental services, and will see children for free.