To acquire skill in tooth scaling, students aiming to become dentists and dental hygienists train with instructors and on their own. Although this skill requires controlling the scaler with appropriate force from the hand, most self-training systems cannot help trainees improve upon this. Several systems can teach the appropriate magnitude and angle of force through calculus; however, force control also requires an appropriate magnitude and angle of force on the tooth to support the hand using the scaler. This paper presents an evaluation system for effective self-training of the force control for the tooth scaling skill. This system evaluates the skill according to three parameters that are calculated from the measured force during operation: the direction of the supporting force, magnitude of supporting force, and ratio of the supporting force magnitude to the removing force magnitude. These were determined from the force measurement results of many operations by three experts and eighteen novices. A teaching system that incorporates the evaluation system was built. This system presents three scores calculated from the three evaluation parameters after operations by the trainee. If the skill is evaluated to be immature, information for improvement is displayed. Five testees were trained by performing ten operations with the system. The results showed that four testees improved their skill according to the evaluation parameters by force measurement, and three testees improved their skill based on a subjective evaluation by teachers. These results validate the effectiveness of the oronosed teachine system.