A dental handpiece comprises a housing (27) and a tool retaining mechanism (60) for retaining a rotary dental tool (28). The rotary dental tool rotates about a first axis (42) and the mechanism retaining the tool such that the tool extends from the housing along the first axis. A tubular guide member (35) is mounted coaxially with the first axis and has a tubular part for locating in a bore hole of a template. This serves to guide the working path of the handpiece during use. A flange (37) on the guide member extends perpendicularly with respect to the first axis and limits the depth of the rotary dental tool within the bore hole. The dental handpiece may also comprise an adjustment mechanism which adjusts the position of the tool retaining mechanism within the housing, in the direction of the first axis, to vary the length of tool which projects from the housing.
