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Self-Etch Primers provide excellent adhesion to dentin as well as enamel. They outperform Total Etch bonding agents on dentin for numerous reasons. These include increased technique sensitivity with Total Etch bonding agents, collapse of the demineralized collagen of the dentin and increased transudation. (Some Self Etch Primers, notably Prelude SE, do not show any transudation at all.)
More on this here:
http://rickwilsondmd.typepad.com/ri...-the-finest-composite-resin-restorations.html
Self Etch Primers employ weak acids to demineralize the smear layer and approximately 10 microns of dentin. Several things can interfere with proper etching by these weak acids. Handpiece oil, chlorhexidine (don't scrub with it!) and blood will interfere with the self-etching process.
Interestingly, strong acids, like the 37% phosphoric etchants we use for Total Etch, also interfere with the action of weaker acids of Self Etch Primers on dentin. And don't try to etch "only the enamel:" as you rinse it away, you're etching the dentin with strong acids.
A detailed exposition can be found in this excellent review article by Pashley:
http://www.dentistrytoday.com/materials/1483
Acidic anticoagulants also interfere with Self Etch Primers. Hemodent and other dental anticoagulants, placed on gingival retraction cord, can totally ruin your bond. Their pH is, like 37% phosphoric acid, around 1.0. In other words, you might as well be etching your tooth when you use Hemodent or similar products.
What to do about this when gingival retraction is desired around, say, a Class V lesion or during a crown buildup? How can we stop bleeding but also not ruin our Self Etch bond with strong acids?
One answer is: use Visine.
Dr. Ray Bertollotti clued me in to this years ago. Let's look at the stats on two commonly used hemostatic agents and Visine.
For reference, the pH of 37% Phosphoric Acid is 1.0. This, then, is our yardstick for what constitutes a "strong" etching acid. Prelude SE, the finest Self Etch Primer today, has a pH of 1.7. (Remember that pH is not a linear scale!)
Hemodent
Active Ingredient: Aluminum Chloride
pH: 1.2
Cost: 40cc (1.35 oz) = $55.99
Hemoban
Active Ingredient: Aluminum Chloride
pH: 1.6
Cost: 1.0 oz = $43.99
Visine
Active Ingredients: Potassium Chloride, Tetrahydrozoline Hydrochloride
pH: 7.4. (Neutral/mildly basic.)
Cost: 1.0 oz = $5.99
I have not considered hemostatic agents based on ferrous sulfate, as that substance directly interferes with dental adhesion.
What we find with our little analysis is that the commercially available dental hemostatic agents have an unacceptably low pH and interfere with dentin bonding, and also cost ten times as much as Visine. Further, in my experience, Visine actually works better to stop gingival bleeding. (So does a laser, but that's another topic.)
When creating dental adhesion with Self Etch Primers, avoid strong acids, handpiece oil (run them with water spray before bringing to your patient), chlorhexidine and of course blood. And when gingival bleeding is a complication, consider using Visine as your hemostatic agent, as it will not damage the dentin bond you are trying to create, and it costs 1/10 of what dental propietary hemostatic agents cost.
(I make my own etch too...)
http://rickwilsondmd.typepad.com/ri...-the-finest-composite-resin-restorations.html
Self Etch Primers employ weak acids to demineralize the smear layer and approximately 10 microns of dentin. Several things can interfere with proper etching by these weak acids. Handpiece oil, chlorhexidine (don't scrub with it!) and blood will interfere with the self-etching process.
Interestingly, strong acids, like the 37% phosphoric etchants we use for Total Etch, also interfere with the action of weaker acids of Self Etch Primers on dentin. And don't try to etch "only the enamel:" as you rinse it away, you're etching the dentin with strong acids.
A detailed exposition can be found in this excellent review article by Pashley:
http://www.dentistrytoday.com/materials/1483
Acidic anticoagulants also interfere with Self Etch Primers. Hemodent and other dental anticoagulants, placed on gingival retraction cord, can totally ruin your bond. Their pH is, like 37% phosphoric acid, around 1.0. In other words, you might as well be etching your tooth when you use Hemodent or similar products.
What to do about this when gingival retraction is desired around, say, a Class V lesion or during a crown buildup? How can we stop bleeding but also not ruin our Self Etch bond with strong acids?
One answer is: use Visine.
Dr. Ray Bertollotti clued me in to this years ago. Let's look at the stats on two commonly used hemostatic agents and Visine.
For reference, the pH of 37% Phosphoric Acid is 1.0. This, then, is our yardstick for what constitutes a "strong" etching acid. Prelude SE, the finest Self Etch Primer today, has a pH of 1.7. (Remember that pH is not a linear scale!)
Hemodent
Active Ingredient: Aluminum Chloride
pH: 1.2
Cost: 40cc (1.35 oz) = $55.99
Hemoban
Active Ingredient: Aluminum Chloride
pH: 1.6
Cost: 1.0 oz = $43.99
Visine
Active Ingredients: Potassium Chloride, Tetrahydrozoline Hydrochloride
pH: 7.4. (Neutral/mildly basic.)
Cost: 1.0 oz = $5.99
I have not considered hemostatic agents based on ferrous sulfate, as that substance directly interferes with dental adhesion.
What we find with our little analysis is that the commercially available dental hemostatic agents have an unacceptably low pH and interfere with dentin bonding, and also cost ten times as much as Visine. Further, in my experience, Visine actually works better to stop gingival bleeding. (So does a laser, but that's another topic.)
When creating dental adhesion with Self Etch Primers, avoid strong acids, handpiece oil (run them with water spray before bringing to your patient), chlorhexidine and of course blood. And when gingival bleeding is a complication, consider using Visine as your hemostatic agent, as it will not damage the dentin bond you are trying to create, and it costs 1/10 of what dental propietary hemostatic agents cost.
(I make my own etch too...)
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