I have a mandible hairline break in the jaw what is the treatment for this?

Mandible fracture: How old are you? do you have teeth surrounding the fracture? what did the doctor who ordered the x-ray tell you? usually with a non-displaced, hair-line fracture management consists of soft diet and decreasing repetitive stress (chewing gum) and eliminating external trauma. Can take Motrin, aspirin or advil (ibuprofen) for any discomfort. it will take around 3 months to achieve sufficient healing.

Depends: Depends on many factors. If no displacement, most patients can be managed with non-chew diet and close follow up. Make sure you're being managed by a board certified oral surgeon.