My back teeth keep chipping. What would a dentist do to stop this. My wisdom teeth are 90% through. I have very good oral hygiene and have no fillings?

? grinding. Bruxism, or grinding your teeth, can cause this to happen. Check with your dentist to find out why this is happening.
Possible Bruxism. Bruxism can cause teeth to chip away by allowing too much constant pressure continually on these teeth. Have your dentist check for this type of wear.
Possible orthodontic. At 33 years old, i would assume that the most common cause of chipping teeth (assuming there is no tooth decay), would be a mal-aligned bite. The uneven pressure during eating and closing would very likely cause teeth to chip and break. If you can not get braces right away to fix your bite, you might want to consider a bite guard to protect your teeth from additional damage until you get braces.
Possibly Grinding. Chipping could be the result of teeth grinding or poor occlusion(bite). I would consult your dentist.
Chipping molars. Your erupting "wisdom teeth" may be crowding your other molars so that chipping is occurring. See a dentist or oral surgeon for ways to alleviate the problem: may be simple mouth guard or possibly surgery to remove the wisdom teeth.
Multiple. Could be fractures in teeth from trauma, weakened enamel from cavities, malpositioned teeth, or grinding habit. In any event your dentist will have the correct solution for your problem. Please make an appointment for examination and rx.