What band of treatment is the construction of trays for the application of medicaments like fluoride?

Trays (such as fluoride trays) aren't defined as an item of care in the Dental Charges Regulations, they're effectively a form of tool used to deliver care.

As such, they're not a 'treatment' and no UDA are appropriate with regard to the provision or use of these trays. The UDA is actually credited for the treatment being carried out (such as the application of the fluoride varnish itself).