Local anesthetic buffering system

March 1, 2012
Onpharma system is easy to use

Onpharma system is easy to use

by Tricia Osuna, RDH, BS, FAADH

Searching for new products while strolling the aisles in an exhibit hall at a dental convention is one of my favorite things to do. During the Chicago Midwinter Meeting in 2010, I was invited by my colleague, Lory Laughter, RDH, to attend a brief presentation about a “soon to be” launched local anesthetic product. Not only was I honored that Lory extended the invitation, I was also intrigued by what she shared with me about the innovation in the world of anesthetics.

The presentation was on a local anesthetic buffering system by Onpharma in Northern California. I was aware of buffering anesthetics in medicine, but not in dentistry. To be honest, I did not totally understand how it might work with the time allowed in a dental appointment, especially in dental hygiene.

The Onpharma process of buffering is a three-part system: the Onset mixing pen, cartridge connector, and a sodium bicarbonate injection solution — 8.4% USP neutralizing additive solution. These three components together with your addition of a 1.8 ml cartridge of local anesthetic compile the entire buffering process for a clinician.

The Onset mixing pen is the device used to mix the two solutions. By simply opening the pen and adding the cartridge of sodium bicarbonate — securing that cartridge, then adding the connector and the 1.8 ml local anesthetic cartridge — the buffering is ready to take place. The mixing pen is designed to dispense a specific amount of solution through the connector and into the anesthetic cartridge. The buffering is a 10 to 1 ratio, so the dial would be placed at 18 for a 1.8 ml cartridge.

The process is very simple; dial the specific number on the pen and then depress the button, which moves the bicarbonate solution through the connector and into the anesthetic. Simultaneously, 10% of the anesthetic is removed from the cartridge to preserve the standard volume. The local anesthetic cartridge is then removed from the mixing pen, placed into a syringe of your choice, and administered in the normal manner to a patient.

After seeing the buffering process demonstrated, I was intrigued and wanted to further understand the concept. How would it benefit the patient, and how would I explain this to patients and team members? There are quite a few articles on this topic; however, this statement from Burns et al. was a wonderful tool to help with the discussion:

The pain caused by infiltration of anesthetic solutions into the skin is largely attributed to their acidity. Solutions with lower pH cause increased pain by two different mechanisms. The acidity of the solution causes a burning sensation when infiltrated into more neutral tissues due to tissue irritation. In addition, at a lower pH, less of the anesthetic is in its active, freely diffusible form, leading to a prolonged time until onset of anesthesia. In a more neutral, buffered solution, the area is anesthetized more quickly and further infiltration is less painful.1

After attending the presentation, reading the materials, and having conversations with company representatives, I decided to clinically test this product on a dentist colleague as well as being a patient myself. The experience was quite surprising! Normally, I have no issues at all with local anesthetic being administered, so I was of the opinion that “I don’t need something like this; however, my patients might.” Additional questions were focused on the amount of time involved in the setup of the product and how it is used chairside.

The three components of the system: pen/buffering agent/connector are very easily assembled, and the process of dialing/buffering/setting up the clinical syringe took no time at all. I can honestly say that I was amazed at the simplicity of the process and how it felt — or should I say, how it did not feel! The movement of the solution through the tissue was barely, if at all, perceptible. I was also surprised that it worked almost immediately. By raising the pH of the anesthetic, you not only eliminate the sting of the injection but also expedite onset time of profound anesthesia, which is a benefit to a lot of busy practices. I believe now that in all of these years of being a dental patient, I had learned to accept what an injection was “supposed” to feel like and never knew there was an alternative.

Apparently, there is some truth to the saying that you really do not know what you have until it is gone! In this case, no longer having the sensation of administration of the local anesthetic was an amazing benefit and one I know that clinicians can truly appreciate. RDH

Tricia Osuna, RDH, BS, FAADH, is a University of Southern California graduate and immediate past president of the American Academy of Dental Hygiene. Tricia has over 34 years of experience as a dental hygienist. She is a career-long CDHA/ADHA member and a previous member of the Dental Board of California. Licensed in both California and New York, her experiences traverse the dental hygiene arena in a very unique way with a variety of roles in dental hygiene including clinician, educator, consultant, international presenter, author, and mentor, as well as business owner and president of Professional Insights, Inc.


1. Burns CA, et al., Decreasing the pain of local anesthesia: A prospective, double-blind comparison of buffered, premixed 1% lidocaine with epinephrine versus 1% lidocaine freshly mixed with epinephrine.

More RDH Articles
Past RDH Issues