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To perform the highest quality restorative dentistry possible, it goes without saying that there should not be much bleeding present at the preparation or seat appointment. At each of these appointments, bleeding typically is a sign of iatrogenic dentistry, or bad treatment planning on the dentist's part.
At the prep appointment, there is always potential for bleeding since we are using a high-speed handpiece and a diamond bur near the gingival tissues. Lacerating the tissues will make preparation more difficult, especially as we finalize the margin of the preparation. It also poses a problem because we are not sure how the tissue will heal, and whether or not it will recede from the margin.
When it comes to taking impressions, bleeding can compromise ideal results. The two most popular impression materials for final crown and bridge impressions are polyvinyl siloxanes (addition reaction silicones) and polyether materials. By nature, polyvinyls are hydrophobic, and additives are introduced into the material to make it somewhat more hydrophilic. This hydrophilicity applies to water only; saliva and blood do not count.
Polyethers, on the other hand, are naturally hydrophilic, but they still do not perform well in the presence of blood or saliva. With either class of impression material, the cleaner and drier the field, the...