Antibiotic therapy for oral infections is described in the context of the determination of microorganisms involved and the formation of resistance to antibiotics. The indications are shown and in 115 cases the microorganisms responsible for the infection and their resistance are enumerated. It is alarming to know that increasingly multiple resistances to antibiotics are discovered. This increase is particularly observed in Tetracyclin and Trimethoprim-Sulfamethoxazol. Finally antibiotic therapies in oral infections are recommended.