I sent an email to the doctor in charge of the Manuka Honey study asking her about the risk of tooth decay. She sent me the following reference.

"This is taken from a reference (Rasghad et al)"

'Pure honey is acidic, with a pH of
around 3.9. A solubility-reducing factor present in
honey can activate in the absence of saliva.
Honey applied to radiation-induced xerotic mucosa
increases the micro-hardness of enamel, thereby preventing
caries.'

I hope this address your concerns.