Identifying and treating the second mesiobuccal root canal in maxillary second molars is improved by modified access preparation and probing the fissure or groove between the mesiobuccal and palatal canal orifices.

• 改良髓腔入口和探查近中颊根根管口与腭根根管口之间发育沟或暗线的方法,有利于发现和治疗上颌第二磨牙近中颊根第二根管。