Does it matter whether a doctor uses the micro cannula technique for a nasolabial fold Bellafill injection?

Thank you for your question. 
Bellafill can be injected with cannula or traditional needle.  The method of injection does not change results. By using a cannula there may be less bruising and swelling but each patient is so individualized that it’s hard to predict bruising and swelling. The most important is a well trained injector, not the method used for injection.
Please consult a local board certified facial plastic surgeon for more information and a comprehensive consultation 

The short answer is the same complications with injection with a needle can also happen with cannulas.  Either can give good results.  What matters most is comfort level and preference of the injector.  Cannulas may allow for fewer needle sticks and therefore less bruising but there are many ways to reduce bruising.  The patient's genetics, skin condition and medications are also a factor.  Overall results, however should be comparable so that needn't be the deciding factor.