Dental hand piece or angle piece with a rotating tool

A dental hand piece or angle piece comprising:

• a tool;
• a radial upper rolling bearing;
• and
• a radial lower rolling bearing;
• the tool is configured to be driven via a rotating drive element arranged in a housing, the rotating drive element is mounted in the housing by the radial upper rolling bearing and the radial lower rolling bearing, each rolling bearing having an axial abutment surface and the housing having mating surfaces formed by a corresponding axial countersurface that corresponds to the upper rolling bearing and another corresponding axial countersurface that corresponds to the lower rolling bearing, and the rolling bearings being axially preloaded relative to the housing via at least one spring element having axial contact surfaces,
• each rolling bearing having an outer ring with an end face which is at least partially designed as an axial abutment surface,
• an axial bearing arrangement of each outer ring of the rolling bearings taking place via the axial abutment surface on the outer ring, wherein the axial abutment surface of the upper rolling bearing directly abuts the corresponding axial countersurface in the housing and the axial abutment surface of the lower rolling bearing indirectly abuts said another corresponding axial countersurface in the housing with the interposition of the at least one spring element,
• wherein an optimal coefficient of friction for the static friction of the axial abutment surface on the end face of the outer ring of the upper rolling bearing to the corresponding axial countersurface and for the axial abutment surface on the end face of the outer ring of the lower rolling bearing and the another corresponding axial countersurface to the contact surfaces of the spring element are formed from an optimal coefficient of friction range by configuring one or more selected surfaces chosen from the list consisting of the axial abutment surfaces, the axial countersurface, the another axial countersurface, and the axial contact surfaces, to have a surface roughness having a profile depth of 8 μm-18 μm and/or a Rz of 4 μm to 14 μm.