ANNOTATION
Dissection of teeth by ultrasound
The principle of operation of these devices is that the preparation of teeth is due to high frequency vibration of instruments under the influence of ultrasound.
Laser preparation
To prepare the teeth, pulsed lasers are used, the effect of which is that water under the laser beam in the dental tissues becomes very hot. This leads to microscopic violations of the integrity of the enamel or dentin, the pieces of which are immediately cooled and removed with a special water-air mixture.
Air-abrasive preparation
When using this method, instead of a rotating drill and drill, an air mixture with an abrasive powder is used, which is fed at a sufficiently high pressure. When exposed to enamel or dentin, this combination causes fine destruction and removal of tooth dust.
Chemical preparation
The method of chemical exposure consists in the use of active substances (most often acids), which soften enamel and dentin with the subsequent removal of the destroyed tissues.
Rules of preparation for the tab:
- preparation is carried out with adequate anesthesia with a sharp centered tool at high speed turbine tip with air-water cooling, considering the safety zones (NG Abolmasov);
-all external walls must be diverged (3-12º);
-form cavity must be atypical;
-pulpiric wall should be of sufficient thickness (for vital teeth);
- when cavities are formed in the proximal areas, a planar section is first produced;
- For the metal tabs, a fold is made on the enamel edge at an angle of 45º to ⅓ the thickness of the layer;
-For CEREC-restorations, the fold is not created
-formation of the cavity is completed by smoothing the edges;
the bottom of the cavity must be perpendicular to the vertically acting forces of pressure, but not the vertical axis of the tooth!
A real-time image is a still image that is a three-dimensional image called an optical snapshot.
Algorithm for removing the optical impression
1. Introduction of registration data, design type and designation of the tooth to be restored on virtual models to the computer memory;
2. Overlay of the cofferdam;
3. Application of CEREC-Liquid with a brush and a uniform distribution of the liquid to a semi-dry state on the subject of the survey;
4. Application of anti-glare CEREC powder (spray) on the subject;
5. Assessment of the quality of matting of the survey area;
6. Setting the computer cursor to the icon "Snapshot of the preparation field";
7. Verification of the purity of the prism glass on the 3D camera of the CEREC 3D device;
8. Positioning the camera with support on the "caliper" above the shooting area;
9. Turn on the camera by lifting the pedal and holding it in this position;
10. Center the camera for optimal display of the object;
11. Fixing the image by lowering the pedal;
12. Evaluation of image quality on the monitor;
13. Save a snapshot in the computer image directory;
14. If necessary, taking additional pictures (extended shooting), monitoring their quality and saving in the image catalog;
15. Quality control 3D CEREC-impression.
Errors in the matting stage
1. The cervical margin is closed - there is no clear boundary of the preparation;
2. Excessive amount of powder on the cervical margin;
3. Excessive amount of powder at the occlusal boundaries of the preparation zone;
4. Insufficient matting of the model;
5. Tightening the process of obtaining an optical CEREC-impression.
Errors in obtaining an optical impression
1. Poor image;
2. Not a clear image;
3. Too much light;
4. Incorrect camera tilt;
5. Incorrect focus in the cervical direction;
6. Incorrect focusing in the occlusal direction;
7. Powder stains;