[The realization of a wear-timing device for clarifying the scientific questions presented in orthodontics].

A timing device for removable orthodontic appliances is described. The measurement system includes a quartz digital clock at the timer. A reed switch serves as a sensor and is activated by a magnetic device fastened directly or by an orthodontic band to a molar tooth. A changeover reedswitch prevents manipulation by the patient. As a timing device the system provides great accuracy. The high-speed capability of the device permits further scientific application: Installation of two timing devices in a single Bionator permits selective timing (e.g. biting contact during wear of the appliance).