By Fred C. Quarnstrom, DDS, FADSA, FAGD, FICD, FACD, CDC, FACD
Local anesthesia is remarkably successful. However, we have all had patients who simply will not go numb. Somehow these patients always seem to be the ones who also are apprehensive. We all have pain inhibition systems and body-produced chemicals that help lessen pain, endorphins and serotonin being two groups of endogenous chemicals. There is some thought that part of the reason why these patients are apprehensive is because they always have trouble with anesthesia. Trauma always gives them more pain than other patients having the same procedure. There is some evidence that this is genetic.
It is very frustrating for both the patient and the dentist when it is impossible to get profound local anesthesia. Our scheduling is such that we need a predictable way to achieve anesthesia with all patients; no one likes to cause pain for their patients.
When the typical block or infiltration fails, intraosseous injections are an alternative. This technique has been described over many years using a variety of techniques and equipment.
- Early techniques required a large needle to perforate the cortical bone. Injection was then done into the medullary bone with this large needle.
- Recently, devices became available that perforate the cortical bone with a needle that rotates in a slow-speedhand piece. A 31-gauge needle is then threaded into this hole and local anesthetic is injected into the medullary space (Figs. 1, 2).
- Another device injected local anesthetic through the needle that was used to perforate while it was attached to a handpiece.
- Some of us used PDL, periodontal ligament, injections when anesthesia failed. A needle was threaded into the bone adjacent to the tooth root and local anesthetic was injected. Some felt it was important for the bevel of the needle to be toward or away from the root. I had assumed that the local stayed in the PDL space and worked its way to the apex of the root where it blocked the nerve entering the root. A later study showed that it was an intraosseous injection. When the solution was tracked, it had entered the medullary space and did not stay in the PDL space. The PDL space we see so clearly in X-rays is an X-ray artifact. The tooth socket does not have a dense lining of bone.
Fig. 1 — The blue hub is the needle. The perforator has the attachment to fit into a low-speed handpiece. Both come sterile with a plastic sheath to protect the staff from the sharp end after the injection.
Fig. 2 — The perforator is in the slow-speed contra-angle, and the needle is in the syringe.I did a study of the Stabident device (see bullet point 2 above), an intraosseous injection device. The Stabident has a perforator needle that goes in a slow-speed contra-angle handpiece.
- First put a drop of local anesthetic in the attached gingiva distal to the tooth you want to anesthetize.
- Immediately perforate with the rotating perforator (Fig 3).
- Remove the perforator and thread a 31-gauge needle into this hole (Fig 4).
- Inject very slowly about 1 cc of local anesthetic. It is important to inject very slowly as the drug is absorbed almost as rapidly as if it were injected intravenously (Fig 5).
- The tooth is numb within seconds (Fig. 6, 7).
Fig. 3 — The perforator is perforating between the teeth distal to the tooth you wish to anesthetize.
Fig. 4 — The needle is shown probing for the perforation.
Fig. 5 — The needle has been threaded into perforation and solution is being injected.
Fig. 6 — The times vs. reading of the pulp tester shows intraosseous anesthesia is clearly faster.
Fig. 7 — This chart shows the statistical differences of the three techniques. I found in a study of 60 patients of intraosseous injections and more conventional blocks and infiltrations that only one patient responded to an electronic pulp tester at 30 seconds when using intraosseous injections. Infra alveolar blocks took eight minutes and maxillary infiltrations took three minutes to achieve anesthesia. The hardest part of this injection is to find the hole left in the bone from the perforator. As I draw the perforator out of the bone, I do not take my eye off the hole. The assistant hands me the syringe with the 31-gauge needle, and without looking away, I carefully insert the needle. There usually is a small drop of blood to mark the spot. If it is a large drop, it may be necessary for the assistant to blow the drop away with the air syringe so you can see the exact spot of the perforation. Once in the hole, insert the needle to the hub and inject very slowly.If you are using a solution with epinephrine, mention to the patient that his/her heart may beat harder and faster. If you inject very, very slowly, it is less of a problem. Better yet, use an anesthetic that does not use epinephrine. There have been reports that the perforator has broken or pulled out of the handpiece adaptor. A small needle holder should always be available on the bracket table. In the event it should break, you probably will be able to grasp it with the needle holder if you do it immediately. If it disappears into the tissue, it is best to immediately refer the patient to an oral surgeon. Present systems seem to have solved this problem.This is a quick, easy technique that has a very high success rate.
Fred C. Quarnstrom, DDS, FADSA, FAGD, FICD, FACD, CDC, FACD, graduated from the University of Washington Dental School in 1964 and started his dental career as a dental officer in the United States Navy. He served with the Marine Corps and a Naval Construction Battalion, making the first amphibious assault in Vietnam at Chu Lai. After the Navy experience, he spent a year at the Washington Hospital Center in Washington, DC, in the first year of a medical residency in anesthesia. He has received fellowships in the Academy of General Dentistry, American Dental Society of Anesthesiology, International College of Dentistry, and the American College of Dentistry. He is a diplomate of the American Board of Dental Anesthesiology and the National Board of Dental Anesthesiology. He is a certified dental insurance consultant of the American Association of Dental Consultants. He has presented more than 500 continuing-education courses on nitrous oxide sedation, practice management, computer usage, electronic dental anesthesia, and IV and Halcion oral sedation. He holds the position of clinical assistant professor in the Department of Dental Public Health Sciences at the University of Washington School of Dentistry and the Faculty of Dentistry University of British Columbia. He has authored 45 papers, three manuals, two chapters in books, a book for dental consumers titled “Open Wider: Your Wallet Not Your Mouth, A Consumer’s Guide to Dentistry,” and continues to do research in nitrous oxide sedation, electronic dental anesthesia, and Halcion oral sedation. He has been in a private general practice in Seattle since 1967. Contact him at http://faculty.washington.edu/quarn and http://openwider.org, or by e-mail at [email protected].
