The smaller the tooth preparation, the more aesthetically pleasing the porcelain crown manufactured by the lab will be. (Of course, it shouldn’t be excessively small: 1. Avoid pulp exposure 2. Ensure good retention);
The deeper and wider the labial shoulder is prepared on anterior teeth, the better the outcome of the restored porcelain crown will be;
Preparing a 45-degree bevel on the incisal edge of the labial side of anterior teeth helps with seating and retraction;
When preparing a full mouth of porcelain crowns, determining the occlusal height is crucial. You can first prepare the upper and lower teeth on one side and take a bite registration, then prepare the other side, having the patient bite according to the previously taken bite registration to capture the other side. Another simpler method is to retain teeth 6 or 7 with their occlusal relationship, take a bite registration, and then prepare these four teeth;
If a wax bite is needed to determine the occlusal relationship, the wax should not be too wide or thick, just slightly wider than the occlusal surface. Otherwise, as the wax hardens, it will compress the periodontal soft tissue, causing premature contact at the gingiva when placed on the model, leading to errors;
When taking an impression, use an air syringe to dry the abutment tooth, especially around the shoulder. After mixing the impression material, use a finger to apply a small amount evenly over the abutment tooth and shoulder, then take a full impression. This ensures the shoulder area is clearly and accurately captured without bubbles;
If a porcelain crown needs to be tried in for a few days, we usually use temporary cementation with eugenol cement. If too little is used, it won’t hold; too much makes crown removal difficult. Adjust the power of the scaler to maximum and vibrate at the lingual gingival margin, and the porcelain crown can be easily removed;
When permanently cementing a well-fitting porcelain crown, after removing excess cement, use a probe to detach any remaining adhesive along the shoulder at the subgingival area, which can reduce the incidence of gingivitis;
For making temporary crowns, there is a simple method: before tooth preparation, take an impression with impression material but do not pour it with stone, just soak it in cold water, then proceed with tooth preparation. When making the temporary crown, place the mixed self-curing resin (make it slightly runny) into the pre-taken impression and place it in the patient’s mouth. Once the resin sets, remove it, requiring only minimal adjustment. (The result will resemble the patient’s original tooth);
Do not make the temporary crown too attractive, or the patient might not return for the porcelain crown, especially those who haven’t fully paid;
During tooth preparation, if you notice a color change to white at any point, stop immediately, as further drilling will expose the pulp!
The gingival edge of a porcelain crown is the weakest point, and if it’s made too long, adjustments can be troublesome and prone to porcelain chipping. Here’s a tip: when adjusting the gingival edge, do not grind both metal and porcelain together. First, create a bevel from the porcelain towards the metal, then adjust the metal length, which prevents porcelain from chipping.
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