By Victoria L. Wallace, CDA, RDA
First order of business is to thank PennWell and it’s supporters for putting together the recent Professional Dental Assisting conference in Indianapolis. A meeting with a focus on dental assistants ... thanks for thinking of us! If you didn’t make it to Indy, I hope to see many of you at my adhesive troubleshooting lecture and hands-on workshop in Norfolk during PDA 2008. It is going to be another great meeting.
I would also like to comment on the Dental Assistant interview in the first publication. The interviewee, a dental assistant, made the comment that dental assistants don’t get enough attention at the trade shows. This makes me sad to hear. Being a dental assistant and a dental manufacturer’s sales rep, I can relate to what she has stated. I rejoice that someone is speaking up. I am fortunate to work for a company that recognizes dental assistants as an important part of the team, and supports the ADAA. Dental assistants help to make many product decisions, and are many times the one that has to troubleshoot if a problem should arise. I say...Corporations, pay attention to us please. More and more state associations are starting to provide CE courses geared towards and presented by, dental assistants. Hang in there and keep the faith. All good things work out in the end.
As far as education, it will never end. Our technology is hard to keep up with, hence the meaning behind my writings. We’ve discussed one aspect of cosmetic dentistry, tooth whitening, and today we will move on to another huge arena of dentistry...resin bonding, or adhesive dentistry.
Again, the dental assistant plays a very important role when assisting the doctor with an adhesive procedure. Setting up, preparing the product to be used, handing the proper chemistry when required, and the list goes on. To many times I’ve asked a doctor what he/she is currently using for bonding and they usually turn to their dental assistant for the answer. Please, no disrespect to dentists (I’ve spent my whole life with them), but yes, there you have it...the dentist depends on the dental assistant to hand the proper product in proper sequence. Because changes in adhesive bonding occurs everyday, I am going to try to pass along a few pointers on how to deal with the constant change. Most importantly, to assist in placing the best hybrid layer ever, as this can make or break a restoration.
Bonding Generations
Let’s start with adhesive system categories, or generations as they are called.
About 30 years ago the dental industry changed in a big way. The inception of bonding a resin to a tooth to restore it with a natural look. The first generation of bonding was called 4th generation, and has 3 steps. Fourth generation resins are still widely used, and have had the most testing due to the amount of time they have been in use.
Here is how they work.
- Etch the prepared tooth with a 35% phosphoric acid to cleanse and condition...rinse after 15 seconds and lightly air dry
- Place a priming agent, which most times is a “A” liquid and “B” liquid combined in a dappen dish and placed in the prep and margins with a brush...then air to thin
- The final step is to place an unfilled resin, air thin and cure for 10-15 seconds. (Follow manufacturer’s instructions)
They are all a little bit different, from the amount of times you place the material to the curing time, etc. There is even one 4th generation system that requires the “primer” to be light cured.
Even though the fourth generation systems have more steps, they are proven to provide predictable, long lasting results, and can be very beneficial to the clinician and patient.
However, times are a changin’...
In 1997 cosmetic dentistry was full speed ahead. Oh cool, patients are starting to come to us for a more beautiful smile, sometimes just to improve looks, not oral health. Fun stuff! Our schedules started to fill and time was of importance. Is that the same year that the saying “time is money” started being used...I think so. Because of the faster paced lifestyle we all started experiencing; time spent on a procedure did become important. Hence the introduction of the 5th generation systems. Now instead of 3 steps, a new 2 step chemistry was introduced.
Here is how they work.
- Etch preparation with 35% phosphoric acid to cleanse and condition the tooth...rinse and lightly dry
- Place the bonding resin, which now has the primers incorporated right into the resin. Air thin, and cure.
Wow! Fast. That’s what we were looking for, however, faster isn’t always better. Way you ask? For some strange reason patients seemed to have been experiencing more sensitivity after composite restorations were placed. What was going on? Why is this happening?
Thanks to researchers and manufacturers, the search for an answer began. It seems for the most part, that this great new invention was not being placed according to the instructions. Due to the new chemistry, incorporating the primer and resin together also meant a different placement application. Primers contain drying agents, such as acetone or alcohol. Drying agents “chase water” and helps to pull the resin down into the prepared/open dentinal tubiles. Without moisture present in the prepared tooth structure, the primer can not do its job.
Research found that the need for educating dentists on “wet bonding” was a reason behind the sensitivity issue. We were so used to etching, rinsing and drying, that most of us assumed that is the way 5th generation systems worked too. The words DO NOT DESSICATE became prominent on instructions! We were pretty much drying the tooth so much that we then sealed air in the opened dentinal tubiles with the placement and curing of the resin. Mother Nature eventually takes care of the problem, but it was painful during the interim. We also discovered that a lot of lasers were also being used to cure composites, and that the wavelength of lasers and ARC lights wasn’t broad enough to insure complete polymerization of all different resin chemistries. What an eye opener!
Picture this please. You’ve just opened a new bottle of 5th generation resin. When you place it in the dappen dish to dispense, the consistency is very fluid and very light yellow, right? Now picture the same but only 2-3 months later. The liquid is much thicker and much more yellow. Yes, I noticed that, you say, but why is it different?
Remember the primers and bonding agents are together in the same solution. Primers, being acetone or alcohol, evaporate. Therefore, after some time of squeezing the bottle to dispense the material, when you release the bottle what happens...it sucks in air, and what does air do to evaporative materials? You got it. If you are using a 5th generation system, try to use it up within 2 months. Mark down the date you opened it, and don’t let an opened bottle sit in an operatory you only use for emergencies. Keep it in the refrigerator when not in use.
Also be patient and gentle when air thinning the primer. Go slow and even for just a few seconds longer as to make sure all the carriers are evaporated completely. I know you don’t like the odor from the primers, but please just remember the stronger the smell the fresher the chemistry.
New research became available to help resolve the sensitivity issue, and with that came some more new resin chemistry. This new system is called; you guessed it, 6th generation bonding.
Another two step system, but now the etchant and primer are together. This new generation is called self-etching. A certain issue arose that reviewed the fact that by etching the hard tissue with phosphoric acid was like incising soft tissue. We were basically creating an open wound. With the lowered acidity of the self-etching primers, complete smear layer removal is not achieved and a superficial conditioning is relied on for marginal strength and wearability.
Let’s review the steps of Self-etching systems...
- Apply self-etching primer to the prepared tooth
(How many times? That depends on the manufacturer) Air thin - Apply bonding resin, air thin and cure according to manufacturer’s recommendations
Seems pretty simple, and doesn’t take much longer to place than the 5th generation resins. And my patients aren’t having as much sensitivity. This is cool and I love dentistry much better now.
If you haven’t noticed already, I’ll just remind you again...
Follow Manufacturer’s Recommended Procedure for Application or READ THE DIRECTIONS! I mean that in a nice way.
To keep you excited about adhesive dentistry, this article will continue with the next publication of Dental Office. I know you will be waiting by the mailbox for the next article in which we will continue the discussion and debate of bonding generations and tips to be a Winner at the Adhesive Game.
A quick “thank you” to all of you that e-mailed or called me with nice comments on the tooth whitening tips. It is very rewarding to be a help towards making your dental days a little bit better.
Until next time, be safe,
be happy and never stop Smiling
Victoria
Biographical Sketch
Victoria L. Wallace has been a CDA, RDA, since 1976. Her chairside career has included general dentistry and cosmetic/esthetic dentistry. Wallace has lectured nationally and internationally on dental products and procedures. She has a strong interest in tooth whitening and adhesive dentistry.
In 1996, Wallace started working for Ultradent Products, Inc. She has been a Product Education Specialist, the West Coast Regional Manager, and is currently the Western U.S. Major Accounts Manager.
Wallace is an active member of the ADAA, president of the Nevada Dental Assistants Association and president of her local society. She also serves as a director for the American Dental Assistants Association Foundation.
