THE USE OF SILICONE KEY AND METER CONVERGENCE ANGLE OF THE TOOTH TO CONTROL THE ACCURACY OF THE TOOTH PREPARATION FOR METAL-CERAMIC CROWNS
Relevance of the topic. Technology for manufacturing metal-ceramic crowns and bridges provides special training abutment teeth, which differs substantially from that in the manufacture of other types of fixed structures. Accuracy of preparation, strict observance of the sequence and content of clinical and laboratory stages in the future provides a good retention of the prosthesis and high aesthetic appearance. To determine the depth of the preparation of dental hard tissues several methods. One involves applying a predetermined amount of marking grooves on the surface of the labial and lingual as well as in the neck of the tooth and the cutting edge. Several authors for this purpose use silicone key. Both methods only regulate the depth of preparation of dental hard tissues and did not allow to take into account the value of the bevel approximal surfaces, so-called angle of convergence. As you know, it depends on the type of prosthesis and group membership teeth. In the manufacture of single metal crowns it is for the front teeth 5 to 7 degrees, and to the side, - 7 to 12 degrees. Unfortunately, the doctor without the use of a special device, visually, is not able to accurately determine the value of convergence of interproximal tooth stump walls.
The Aim. Develop meters to determine the angle of convergence of anterior and posterior teeth and the algorithm used in combination with a silicone key at preparing teeth for metal-ceramic crowns.
Scientific novelty and practical significance. First proposed a device for measuring the angle of convergence approximal surfaces of teeth dissected. Application meter convergence angle of the teeth allows precise control over the amount of bevel that provides further smooth the imposition and secure fit metal-ceramic crown on the abutment.
Materials and methods. The most optimal to control the tooth preparation for metal-ceramic crowns, the method of manufacturing silicone key. For this purpose, before the tooth preparation have full anatomic impression silicone base material, which is then cut in half to strictly cutting edge of the front teeth and the center of the chewing surfaces of the side. The resultant two parts: Lip (buccal) and palatal (lingual) is a silicone key. Applying tightly to the teeth alternately vestibular and palatal (buccal) of the silicone key, so you can control the depth of the tooth preparation. In addition to the above, we suggest using the method developed by us gauges convergence angle of the tooth. The technology of their manufacture is that the hot plastic from the polymerization in the dental laboratory fabricated preform - the plate thickness of 1.5 mm and a length of 20 mm and a width of 10 mm. Then, using a protractor made definition and drawing angles and magnitude 5 to 7 degrees. We have specifically taken the extreme magnitude smaller convergence angles anterior and posterior teeth, to have some maximum permissible margin of hard tissues in case of over-preparation.
In the following of plastic plates, billets have cut triangles with given values of angles that are already direct angle meter convergence of the tooth.
After applying the silicone key on the dentition to approximal tooth surface dissected applied measuring convergence angle and thus controlled by the magnitude of the bevel. If the preparation of the contact surface produced is not enough - you can see it clearly and refined.
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