Broken isntrument –challange of the day. This upper third molar was referred to me with pulpitis. One seat treatement was planned. On pre-op x-ray curved and calcificated rootcanals were observed. Mesial sytem seemed very challanging. Capitulation in MB1, DB, and P was easy. Glide path with 0.10 was secured. Mb2 seemed a septum variation, connected to MB1 with one apex. After coronal flearing, X1 broke in DB.Of course it was my fault. Dentin triangle was dominant, not removed properly. It was limited mouth opening, i forced a bit. Tried to remove with UH. I pushed a little bit deeper. Than i decided to bypass. I was succesfull. Than i cleaned the DB, and decided to left the instrument in position. No need to drill more sound dentin, regarding to pulpitus, bypass and cleaning. (Loop was not possible. Than obturation was performed with wvc, and squirting. You can see on post-op, that MB2 was predpared and obturated occasionally! (Vertucci type V.) Shaping: Kerr: 8, 10,15 Protaper SX, Next X1, X2 (MB1) F1, 35/02(P) , 30/02 (DB) US: NSK E8, Satelec Acteon Cleaning: NaOCl 5.25 %, Endoactivator,,US liquid EDTA 15% Obturation: WVC (MB1-2, P) Squirting (DB) (Sytem B Obtura III, AH+, Buchanan plugers)