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Bleaching (Lightening Natural Teeth)
Ceramo-Metal Bonded Restorations
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> Posts, Cores, and Crown Build-ups
Posts, Cores, and Crown Build-ups
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Are the new light cured resins (e.g. G-C Pattern Resin) for direct post fabrication a good substitute for Duralay?
Some of our evaluators prefer them, but because this material is dual cured it may be slower to set and more difficult to use in a canal space. The author prefers to use Duralay.
What about using a resin bonded amalgam for a amalgam post and core? Does the bonding system increase retention or strengthen the tooth?
Although nonbonded amalgam has worked well for years. Bonded amalgam is considered by most to do at least as well or better. One major advantage of bonded amalgam is that an opaque resin liner can be placed between the bonded dentin and the amalgam to reduce the incidence of tooth discoloration. This technique has done very well in our study group programs for restoring endodontically treated molar teeth.
Do you anticipate that composite cores will be more successful with the advent of newer dentin bonding systems?
No. While it may become somewhat more successful, it is inconceivable that a system with 2 dissimilar parts will ever bond. These materials will always be heavily dependent on mechanical support.
You mention that composite cements are usually the best choice for post cementation. Would you use glass ionomers?
Glass ionomer cements are not indicated for use with nonvital teeth. The desiccation of endodontic teeth over time weakens bond strength. Zinc phosphate, although usable is considerably less retentive than bonded composite. Resin cements are the material of choice for all post and core cementations.
What is 10/3?
10/3 is a solution of 10% citric acid and 3% ferric chloride. It effectively conditions dentin to maximize the ability of a dentin primer and adhesive to form a resin impregnated layer (a hybrid layer) for more reliable bonding. It can be made up by a pharmacist or purchased from a chemical supply house (e.g. KHS Polymer Technologies, Inc., Kansas City, Missouri, 64106. Phone: 800-475-4547).
Is there a significant difference in the way it works?
No, many other weak organic acids will do a good job of conditioning dentin. This particular product has done well in our clinical trials in terms of reducing the incidence of postoperative sensitivity.
When will it be available, and should I get it?
It has been available for over 10 years. Many dentin bonding systems (e.g. All-bond, Scotchbond MP, Optibond, etc.) contain other weak acids which condition the dentin effectively.
What if part of the tooth has been destroyed and I can only place a 3/4 encircling ferrule. Is that worth the effort?
Is there a direct restorative bonding system that is as effective and long lasting as a single metal cast post and core to stand up under the kind of forces a ferrule can withstand? Do you think there will ever be?
No. Probably not in our lifetime.
Is there a non-threaded, treated metal post on the market? Or do I have to sandblast and tinplate to get the best bonded effect?
Since most posts need to be adjusted chair side, any pretreatment could be removed. Sandblasting, washing, tin plating, and washing again provides a simple and reliable method to enhance metal resin bonding.
It seems the ferrule effect is so beneficial in creating a restoration that could last a lifetime it should be considered as the first option with other options (stock posts with dissimilar material cores) considered second. What do you think of this?
The ferrule effect, if adjusted properly can reduce apical stresses. However, by itself it will not insure success. The fit of the crown, especially those with shoulder margins, dissipates apical stress since it can load the margin rather than the post and core. And bonding resin to dentin and metal further reduces stress. Using all these features make success more likely.
How do you prepare molar canals for amalgam post and cores?
Prepare them shallow and divergent or retentive with horizontal grooves prepared in the pulp chamber.
Does the eugenol in the sealer cause problems in cementing posts with composite?
It can, but if the canal is cleaned out well with a solvent (e.g. alcohol) the clinical significance is minimized.
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