A.患者取坐位,頭直立,大張口,上頜牙牙合面與地平面平行 B.患者取坐位,頭微仰,半張口,上頜牙牙合面與地平面呈45° C.患者取坐位,頭后仰,大張口,上頜牙牙合面與地平面呈75° D.患者取坐位,頭后仰,大張口,上頜牙牙合面與地平面呈45° E.患者取坐位,頭直立,半張口,上頜牙牙合面與地平面呈45°
A.1%~2% B.0.1%~0.2% C.0.25%~0.75% D.0.25%~0.5% E.2%~3%