Adental handpiece is disclosed which has a head housing, a gear shaft having a gear part with gear teeth and a shaft part extending from the gear part, and a dust control seal sealingly fit on the circumferential surface of the shaft part of the gear shaft. The dust control seal is an annular member, and has a seal body, a first lip projecting radially inwardly from the seal body, and a second lip projecting radially inwardly from the seal body above and spaced apart from the first lip, with a space defined between a contact area between the first lip and the shaft part, and a contact area between the second lip and the shaft part.茲揭示一種齒科用手持機,其具有:頭部殼體;齒輪軸,係具備設有輪齒之齒輪部及自齒輪部延伸之軸部;以及粉屑控制密封,係密封地裝配在齒輪軸之軸部之周面上。粉屑控制密封係環形構件,並具有:密封體;第一唇,自密封體徑向向內突出;以及第二唇,在上方,自密封體徑向向內突出,並與第一唇隔開,有一空隙界定在第一唇與軸部之間的接觸區域,以及在第二唇與軸部之間的接觸區域之間。1a‧‧‧頭部1b‧‧‧頸部2‧‧‧頭頸部4‧‧‧頭部殼體5‧‧‧齒輪軸6‧‧‧保持構件7‧‧‧齒輪部8‧‧‧軸部9‧‧‧粉屑控制密封10‧‧‧蓋38‧‧‧第一唇39‧‧‧第二唇40‧‧‧空隙41‧‧‧齒科處理工具P‧‧‧齒科手持機
