A replacement head for an oral care implement, such as a toothbrush, wherein the replacement head utilizes a specially designed structure for coupling the replacement head to a handle of the oral care implement. In one embodiment, the invention can be a replacement head comprising: a head a tubular sleeve comprising a cavity for receiving a handle a protuberance protruding radially inward from an inner surface of the tubular sleeve for engaging a boss of the stem to impede rotation of the tubular sleeve about the stem in a first angular direction and a locking tab protruding radially inward from the inner surface of the tubular sleeve for engaging an undercut surface of the boss to prevent axial disengagement of the tubular sleeve from the stem, the locking tab circumferentially spaced from the protuberance so that an first axial channel exists therebetween for receiving a section of the boss.一種供一口腔保健用具(例如牙刷)用之替換頭部,其中替換頭部利用一種用於將替換頭部耦接至一口腔保健用具之握把之特別設計的結構。於一實施例中,本發明可以是一替換頭部,包含:一頭部;一管狀套筒,包含一用於容納一握把之空穴;一隆起部,從一管狀套筒之內表面放射狀向內突出,用於啣接一桿之突起部分以阻礙管狀套筒繞著桿朝一第一角度方向之旋轉;以及一鎖定片,從管狀套筒之內表面放射狀向內突出,用於啣接一突起部分之底切表面以避免管狀套筒與桿之軸向分離,鎖定片與隆起部周向隔開,俾能使一第一軸向通道存在於其間,用於容納一突起部分之區段。400‧‧‧替換頭部410‧‧‧頭部部分420‧‧‧管狀套筒424‧‧‧遠端430‧‧‧窗孔500‧‧‧握把501‧‧‧使用者介面510‧‧‧握持部分513‧‧‧外表面530‧‧‧突起部分2000‧‧‧口腔保健用具/牙刷/電動牙刷
