Dr. Keith Wickizer is a dentist and orthodontist that operates out of dental and orthodontic offices in Summerville, Goose Creek, and Mount Pleasant. For more information, please visit www.acuitydentistry.com.
Sorry to hear about your sister. To answer, it really depends on what type of break it was. Most fractures of the jaw due to impact occur along the condyle, or the part of the jaw that pivots; which is actually the weakest point of the mandible. At 6 weeks, the bone is only partially healed. It usually takes 3-6 months for the bone to heal to the point where it is not still fragile. The oral surgeon will most likely prescribe some jaw "exercises" that will aid in healing. You can always ask the surgeon about the exact healing times. It is very important for your sister to follow this regimen, or additional surgeries or braces to realign the teeth may be needed.
Hope this helps!