Jan,

The MG Manual has a section on dentistry:

Myasthenia gravis (MG) may manifest neuromuscular weakness in the head and neck region that produces characteristic features that may provide clues to diagnosis and challenges to dental treatment. Consultation with the patient’s neurologist is recommended prior to dental treatment in order to ascertain the extent of neuromuscular weakness, frequency of neuromuscular exacerbations or crises and to discuss the need for medical management to optimize the treatment outcome in the unstable patient.

Myasthenia Gravis: A Manual for the Health Care Provider (PDF) - page 100

The MG Manual is free. You can download it in PDF format, and it is easily printed.

-Mark-