The invention is directed to a coupling for connecting dental angle pieces with dental handpieces, wherein an outlet point for a light guide is provided near the tool holder in order to illuminate the work place in the mouth of the patient. A corresponding light source being provided either in the angle piece or in the handpiece.
A whole series of dental angle pieces with such light guides are known, but two types have proven to be successful in practice.
In a first known system, the light source is located in the handpiece and the light receiving end of the light guide is located in the angle piece opposite the light source. In order to secure this opposite location, a nose is provided in the coupling, which in other respects is symmetrical with respect to rotation. The nose ensures a correct angular position between the angle piece and the handpiece.
In a second commonly occurring system, the light source is located in the angle piece and is provided with current from the handpiece by means of concentric, circular slip rings at the end face of the coupling regardless of the angular position between the angle piece and the handpiece.
The existence of these known illumination systems brings about a whole series of disadvantages for both the producer of the angle pieces and the dentist. The handpieces are usually manufactured by companies which also produce the patient chairs for dental practices. The producers of the angle pieces generally do not manufacture dental chairs, and the producers of the chairs, in turn, generally do not manufacture angle pieces. The producers of the angle pieces must accordingly take into account the two different systems in production and storage and are compelled to expand their storage space. Of course, this has a disadvantageous effect on costs and delivery times.
The users, in turn, are constrained in the selection of the angle pieces by the handpiece system which they have selected and, if connections for both types of handpieces are provided in their work place, must be very careful not to confuse the corresponding handpieces and, when changing the angle piece, must often change the handpiece as well. This, in turn, is cumbersome and results in problems with the sterilization of the instruments after treating a patient.