Low pH solutions can cause tooth enamel to soften and if you brush them, it is possible to brush off some enamel.
There is another teeth brushing thread here on the forum that talks about the problem. I made a PDF file to show testing I did so we know what to expect when brushing teeth when using MMS1, CDS and CDH.
mmsinfo.org/infosheets/MMS1_Teeth_Brushing_Procedure_pH_Testing_Results.pdf
Much of the pH is determined by the pH of the water used to mix with whatever CLO2 solution you are using.
I did not know about the problem until the lady who started the forum thread brought it to our attention.
As far as knowing the pH of ingested CLO2 solutions, that is not a problem.