Hi again
To expand on my earlier response, here are a couple of potentially useful sites to aid this awful situation;

http://www.adviceguide.org.uk/h_nhs_dental_treatment.pdf
http://www.adviceguide.org.uk/index/family_parent/health.htm
http://www.healthcarecommission.org.uk/aboutus/complaints.cfm
http://www.pals.nhs.uk/cmsContentView.aspx?Itemid=944

This guy went against your specific instructions. Would be very interesting to find out more about this dentist / practice, and how many other instances of ignoring parental requests (etc) have gone on. Do they bother to check the patient's health/status at all before carrying out traditional 'treatments'?!