When a tooth shows discoloration and does not respond to the cold test or electric pulp test (EPT) after a traumatic injury, its diagnosis can be even more difficult due to the lack of proper diagnostic methods to evaluate its vitality. In these case reports, we hope to demonstrate that ultrasound Doppler might be successfully used to evaluate the vitality of the tooth after trauma, and help reduce unnecessary endodontic treatments. In all three of the present cases, the teeth were discolored after traumatic injuries and showed negative responses to the cold test and EPT. However, they showed distinctive vital reactions in the ultrasound Doppler test during the whole observation period. In the first case, the tooth color returned to normal, and the tooth showed a positive response to the cold test and EPT at 10 wk after the injury. In the second case, the tooth color had returned to its normal shade at 10 wk after the traumatic injury but remained insensitive to the cold test and EPT. In the third case, the discoloration was successfully treated with vital tooth bleaching.

Nowadays, oral anticoagulants are commonly prescribed to numerous patients for preventing cardiovascular accident such as thromboembolism. An important side effect of anticoagulant is anti-hemostasis. In a major surgery, the oral anticoagulant therapy (OAT) regimen must be changed before the surgery for proper post-operative bleeding control. However, in a minor dental surgery and endodontic surgery, the necessity for changing or discontinuing the OAT is open to debate. In this study, risks of the consequences were weighed and analyzed. In patients who stop the OAT, the occurrence of thromboembolic complication is rare but the result is fatal. In patients who continuing the OAT, post-operative bleeding can be controlled well with the local hemostatic measures. In the endodontic surgery, there are almost no studies about this issue. The intra-operative bleeding control is particularly important in the endodontic surgery because of its delicate and sensitive procedures such as inspection of resected root surface using dental microscope and retrograde filling. Further studies are necessary about this issue in the viewpoint of endodontic surgery.