When i have my mouth wide open at the dentist the left hand side of my jaw makes small crunching noises is this normal?

Disc derangement: With reduction. Displacement of the disc mostly in an anterior or anteromedial position upon closing and return of the disc to a more normal position on opening characterizes disc displacement with reduction. Patients will usually experience a "click" on opening. It is normal if there is no pain or discomfort. If concerned, see orofacial pain specialist.

Common...Not Normal: Many people have clicking, popping, or crunching in their jaw joints, especially under stress, like at the dentist for longer periods. In fact, about 1/2 of 50-year-olds already have this condition. If there's no pain, it's not serious...yet. You should try to prevent it from getting worse, though, so you don't develop pain or limited function. That's usually easy to do.Your dentist can guide you.