Deep neck infections are rare but potentially fatal complication of pulpal abscess of the teeth. If an infection can progress rapidly from a toothache to a life threatening infection, then it is critical that dentists be able to recognize the danger signs and identify the patients who are at risk. Mediastinitis is a severe inflammatory process involving the connective tissues that fills the intracellular spaces and surrounds the organs in the middle of the chest. This pathology has both an acute and a chronic form and, in most cases, it has an infectious etiology. This study want to expose the experience acquired in the Oral and Maxillo-facial Sciences Department, Policlinico Umberto I, "Sapienza" University of Rome, regarding two clinical cases of disseminated necrotizing mediastinitis starting from an odontogenic abscess. We report two clinical cases of disseminated necrotic mediastinitis with two different medical and surgical approaches. The radiographic and photographic documentation of the patients was collected in the pre-and post-operatively. All patients underwent a CT scan and MRI. Mediastinitis can result from a serious odontogenic abscess, and the extent of its inflammation process must be never underestimated. Dental surgeons play a key role as a correct diagnosis can prevent further increasing of the inflammation process. A late diagnosis and an inadequate draining represent the major causes of the elevated mortality rate of disseminated necrotizing mediastinitis.