FRONT END COLLISON OF VOLVO 740 SW IN WHICH AIR BAGS DID NOT DEPLOY. SON HIT HEAD AND HAD TO BE SEEN IN EMERGENCY ROOM DUE TO POSSIBLE CONCUSSION. MAJOR DAMAGE TO FRONT OF VEHICLE, WHY DIDN'T THE AIR BAGS DEPLOY? PLAN ON TAKING VEHICLE FOR SERVICE REPAIR ESTIMATE, WHAT ARE THE CHANCES OF AIR BAGS DEPLOYING AFTER A FRONT END ACCIDENT, WHEN THEY DID NOT DEPLOY ON IMPACT?