How they do it
A thin impregnated thread is carefully placed into the gingival groove around the ground tooth, which widens the groove for several minutes and stops the leakage of fluid. The thread is then removed and the impression is immediately taken. Without this stage, the edge of the ledge will be blurred, and the crown will lie with a gap - and this is a direct path to caries under the crown and gum inflammation.
Why are the stages counted separately?
Orthopedic treatment consists of clinical and laboratory stages. Some of them - taking impressions, making an individual tray, gum retraction, fixing or removing a crown - are performed independently and are not always included in the main work.
The result directly depends on the quality of these stages: an inaccurate impression or an under-opened edge of the ledge will lead to the fact that the crown will not fit, no matter how well it is made in the laboratory.
What affects accuracy
- selection of impression material for a specific task
- dry field and lack of blood in the ledge area
- correctly opened gingival sulcus
- no deformation of the impression during removal