The present invention relates to a dental and/or surgical instrument (1) comprising a motor that drives a tool by way of a tool holder (24, 25, 27) situated in the head of the dental and/or surgical instrument (1), the tool holder (24, 25, 27) being supported in the head of the dental and/or surgical instrument (1) by at least a first ball bearing (21) and a second ball bearing (22), in which the first ball bearing (21) and the second ball bearing (22) are positioned in a cartridge (10) which is inserted into the head of the dental and/or surgical instrument (1), and in which the cartridge (10) comprises a single bore (80) for the mounting and guiding of both the first ball bearing (21) and the second ball bearing (22). The present invention additionally relates to a cartridge (10) to be inserted into the head of such a dental and/or surgical instrument.