Handpiece (dentistry)
A handpiece is a technical device that serves as a connection between a drill and rotating tools. The handpiece is a transmission instrument with which a rotational force is transmitted to the drill. In contrast to the contra-angle handpiece, the longitudinal axis of the handpiece (the axis of the drive shaft) coincides with the axis of the working part (e.g. the drill).
These drills , milling cutters , mounted grinding tools or sandpaper carriers are attached to the handpiece by means of a clamping device ( chuck or collet) and set in rotation.
With other technical devices, too, without rotating parts, one speaks of a handpiece if the functional part is held in the hand during use, for example:
- the optics of an intraoral camera
- the handle of an ultrasonic dental calculus removal device
- the handle of a powder jet device for cleaning teeth
- the laser handpiece of a medical laser
- the handle of an ax
Dentistry and dental technology
In dentistry , in addition to straight handpieces (dental handpieces), angled instruments, which are known as contra-angles , are also used when processing teeth .
Handpieces are also available in dental technology or on the Dremel .
Handpieces in dental technology are built to be particularly robust and powerful. Dental handpieces are less intended for use in the patient's mouth than for processing dental work (crowns, bridges, prostheses).
The speed of the handpieces must be matched to the task at hand and the strength of the workpiece. Likewise, the speed must not exceed the strength of the clamped rotating body. There are no problems with metal milling machines, while grinding tools with a larger diameter are often subject to a speed limit by the manufacturer.
Most handpieces work without a translation and are marked with a blue ring based on the contra-angle handpieces ( Kavo Dental ).
Both the handpieces commonly used in the dental practice and in the dental laboratory are grasped with the entire hand and guided by the thumb in order to be able to transfer sufficient force with sufficient grip. Contra-angles, on the other hand, are held like a pencil, since less force has to be transmitted, but the work is more delicate.
Shanks for burs, which are intended for technical handpieces and dental handpieces, have a diameter of 2.35 mm, more rarely 3.0 mm (ISO 104 HP = handpiece). The shaft length may not exceed 44.5 mm.
It is driven either by an electric motor that connects directly to the handpiece ( micromotor ), or by a flexible shaft that is driven by a separate, external drive motor.
Strictly speaking, only handpieces with an external motor and flexible shaft are called handpieces, while devices with an integrated motor are called hand drills. However, this distinction has not caught on in practice. Dental contra-angle handpieces are now only designed with an integrated motor, as this eliminates the need for a mechanically sensitive flexible shaft. The starter switch for the dental engine, ie the "handpiece", is operated with the knee. It is an approximately 20 by 30 cm large plate that is operated like a toggle switch by pressing the right knee sideways (to the right) on this plate. This knee switch must be held down while drilling. Since the switch has a stroke of approx. 10 cm, the speed can also be regulated at the same time, with a manually operated controller for the maximum speed on the knee switch.
Similar handpieces are also used by goldsmiths and in pedicure , as well as by engravers.
Ophthalmologists also use handpieces with very small abrasives to clean and smooth the surface of the cornea (cornea of the eye) - in patients who have injured the cornea with iron splinters. Otherwise the iron splinter would rust and the rust would cloud the cornea.
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- Paul Weikart: Materials science for dentists , 4th edition, Carl Hanser Verlag, Munich