Yes. Dental infections are nothing to ignore. Due to the proximity of the oral cavity to the brain, it is possible that a simple dental infection, if left untreated, could travel to the brain through the various facial spaces and lead to death. This is very rare, but people have died from a simple dental infection. See your dentist.
Eventually, it can. Tooth infections were one of the leading causes of death before antibiotics came along. Although antibiotics can clear up most infections, there is no guarantee.. If an infection spreads fast or is resistant to the antibiotics, then a life threatening situation can result. Don't wait to treat...
Yes. Unlikely if you get it treated correctly in enough time to prevent a wild spread of bacteria. You need to see a dentist pronto.
Yes, it can. Complications from tooth infections are rare in this era of antibiotics and modern dentistry. Most of them are diagnosed and treated promptly, and respond well to antibiotics and dental management. However, if untreated, some of them can extend into the neck and/or face, causing serious head and neck infections, including septic thrombophlebitis, airway obstruction from neck swelling and sepsis.