The topic of dental adhesives has consistently complicated the world of dentistry for quite some time. Newer generations of both self-etch and total-etch systems, with the intent of simplifying the process, has actually added a little more confusion.

When compared to self-etch systems, total-etch systems have been said to be more technique-sensitive due to the separate step of etching enamel and dentin. With the self-etch systems being undoubtedly more user-friendly, the total-etch system poses some risks that all dentists need to be aware of.

Over-etching: Over-etching can demineralize too deep a zone. Most hybrid zones are about 10-20 microns in depth, over-etching can lead you to demineralize up to 80 microns in depth, which is too deep for hydrophilic resin to penetrate. This could leave you with a gap of demineralized dentin that will result in a very weak bond. However, a solution to this issue is rather simple: just limit your etching time to 15-20 seconds.

Over-drying:  Drying correctly in total-etch systems means leaving a slightly damp surface to the dentin. This allows the collagen to remain standing up. If a tooth were to be desiccated during this process, you only leave dentinal tubules and virtually nothing for the resin to flow into, basically diminishing the entire hybrid zone. There has been a lot of research around the proper way to dry a tooth with self-etch systems. The best method of drying in terms of bond strength is to simply blot the area with cotton or tissue paper to achieve damp dentin.

Comments

Commenter's Profile Image Andrew Arnouk
August 31st, 2012
Hi Mark, During any dental meeting, whenever there is a lecture about bonding, the room would always be full. Bonding techniques and materials are the least understood subject in dentistry. Thanks, for your article, very informative like your other ones.
Commenter's Profile Image DR FARHAN DURRANI
September 1st, 2012
ETCHING HOW MANY MINUTES AND DRYING WITH WHAT HAS BEEN A CONFUSING ASPECT OF AESTHETIC DENTISTRY, WITH NEWER CONCEPTS EMERGING EVERYDAY
Commenter's Profile Image Bruce LeBlanc
September 8th, 2012
Mark I hope this finds all well for you and I am really excited for you that your journey has taken you to teach at the Spear center It is my strong conviction that what you posted here is factually incorrect and is the foundation that is used to promote the use of self etch products. Your comments about over etching/over drying applies to acetone based products. I have used alcohol based products (Optibond FL) for over 20 years and have recall photos back that long where I did in fact over etch and over dry and what you state is not supported by recall photos I have and clinical observations. I would be glad to send you photos that do in fact make a case that total etch and then using an alcohol based product is in fact state of the art. I have a request -- do you have recall photos at 5 years of restorations you have placed using acid etch products such as Multilink with its self etch primer which is advocated by both cad cam companies. Can you send me some for inlay restorations at 5 years using those products to drbruceleblanc@gmail.com I would also ask Spear faculty that may be advocating the use of these self etch products if they could do the same. I have yet to be supplied with photographic clinical evidence from any clinician or manufacturer, though I have requested as I am doing here, that these weak acid self etch bonding products are living up to their promised performance Thanks Bruce LeBlanc DDS
Commenter's Profile Image Mark J Fleming DDS
September 8th, 2012
Bruce, To answer this simply, your strong conviction is incorrect. Total etch products, like ALL products, have risks. And I am not, nor is Spear Education, is promoting self etch products over other products. I fail to see where in this article where one system is rated over another. I hope this answers your concerns.
Commenter's Profile Image Bruce LeBlanc
September 8th, 2012
Thank You Mark for your reply. YOu stated in your post --- When compared to self-etch systems, total-etch systems have been said to be more technique-sensitive due to the separate step of etching enamel and dentin. With the self-etch systems being undoubtedly more user-friendly, the total-etch system poses some risks that all dentists need to be aware of. -- you also mentioned problems with over drying and over etching. --what are those problems and with what specific products because once again I have not seen those problems with alcohol based systems Let's try it this way 1) What are you basing that self etch is more user friendly in your post. What does that mean. Are you implying they are easier to apply and get the same or better performance results 2) As a point of reference, do you and Spear education teach cementation using self etch systems. Do you personally believe they are equal in performance to the total etch alcohol based systems. If so do you have post op recall photos that you or anyone at Spear education can send to my email to show that the self etch bonding systems you advocate now and in the past are living up to the marketing advocation that they are comparable in performance to total etch systems especially concerning marginal integrity and microleakage and recurrent decay. As I mentioned I would be glad to send you photos at up to 17 years for comparative purposes. The reason for my inquiry is my concern for what I am seeing clinically and what other dentists are reporting to me with the newer generations of bonding agents. It would be a shame if in fact these newer products that are being advocated to replace products with long track records of success are not equal in performance, would you not agree. If they are it would seem you would have documentation clinically. If they are not it would seem you would not advocate them. Thanks Mark Great discussion as always. My best Bruce
Commenter's Profile Image Bruce LeBlanc DDS
September 10th, 2012
Mark ?