外力直接撞击外力直接撞击,咀嚼咬到沙石、咀嚼咬到沙石、碎骨等硬物。碎骨等硬物。be impacted by force,biting be impacted by force,biting hard food.hard food.EtiologyEtiologyhttp:/ characteristicsClinic characteristics按部位分:冠折 Crown fracture根折Root fracture冠根联合折 Crown-root fracturehttp:/ crown fracture 前牙前牙:横折、斜折横折、斜折Anterior tooth:horizontal or inclinedhttp:/ teeth:inclined or verticalhttp:/ root fracturehttp:/ 1/3、根中、根中 1/3、根尖、根尖 1/3cervix-thirds,middle-thirds,apical-thirdshttp:/ 3859根折牙牙髓坏死率为2024，断端间隙利于炎症引流。http:/ can be carried out by
