Are mandibular blocks still necessary?

June 1, 2005
We were all taught the alveolar block in dental school, and it was certainly the toughest injection to learn.

We were all taught the alveolar block in dental school, and it was certainly the toughest injection to learn. Clinicians who have practiced any length of time have concluded that success rates for maxillary and mandibular anesthesia are very different. With thinner bone over the apices of the maxillary teeth and easier access to the nerve blocks in the maxillary, success rates usually approach 95 to 98 percent.

Unfortunately, the same thing cannot be said of the mandible. Besides being an unpleasant injection, the success rate for IA blocks in the mandible are about 80 percent. Because of the mandible’s bone density, the anesthetic solution should be placed to within 1 mm of the target nerve, according to Dr. Stanley Malamed.

Because of anatomical variation of the position of the mandibular foramen and the depth of soft tissue penetration necessary to get there, this injection is missed more than any other. It has a positive aspiration rate of 10 to 15 percent, the highest of all intraoral injection techniques. The patient is also left with unpleasant lingual and lower lip anesthesia. In addition, many dental schools recommend giving this injection with a 25-gauge needle.

For doing a quadrant of dentistry or a whole side, such as the lower left, the IA block still makes sense. However, to use the IA block for one or two teeth strikes me as overkill - that is a lot of soft tissue anesthesia for a couple of teeth. At our lab, most of the cases are one or two adjacent crowns. For these cases, I have stopped giving lower blocks.

The reason for this is twofold. First, I hate waiting eight to 10 minutes for anesthesia to absorb and have the patient not be anesthetized. This can be a schedule killer. The second reason is having to wait eight to 10 minutes - even when a mandibular block does work. I would prefer to do what we do on the maxilla - inject slowly enough so the tooth is anesthetized by the end of the injection.

Thus, it is apparent that mandibular blocks may not be the easiest path to anesthesia. When I discovered a technique that afforded fast and painless anesthesia of lower molars, I was interested. This is for cases in which we are prepping one or two posterior molars only, and want to work quickly.

The first breakthrough I had was finding a strong topical anesthetic. Profound comes in a 30-gram tube and a 10-gram syringe for direct subgingival placement for hygiene uses, packing cord, etc. Sold by Steven’s Pharmacy in Costa Mesa, Calif., the topical can be ordered by calling (714) 540-8911 (in California) or toll-free nationwide at (800) 352-DRUG. The anesthetic works well because it is a combination of prilocaine, lidocaine, and tetracaine. It is unlike most topicals, which contain just benzocaine. The first time I used the anesthetic, I placed some above No. 8 and No. 9, and left it on for a few minutes. To my amazement, I had pulpal anesthesia on these two teeth - just from this topical!

Since then I have found that I can get mild pulpal anesthesia with this anesthetic anywhere the cortical plate of bone is thin. This includes maxillary and mandibular incisors, but not the cuspids. If you need to use a local anesthetic, the injection site is completely anesthetized with Profound, and the patient is ready for a painless injection of anesthetic based on your duration requirements. The absorption of septocaine is so high that, besides using it for maxillary infiltrations, it also works well for mandibular infiltrations including bicuspids and lower anterior teeth.

In order to anesthetize lower molars without the tongue and lower lips, injections in the furcation are effective. I use Profound in a syringe with an 18-gauge disposable Endo-Eze tip from Ultradent, placing the topical into the buccal sulcus and into the furcation. After letting it absorb for 60 to 120 seconds, I can give a painless injection from a standard syringe with a 30-gauge extra short needle. This results in pulpal anesthesia without any of the unwanted soft-tissue effects.

I was surprised that I liked the Dentsply Comfort Control Syringe, too. The syringe does vibrate as it injects, producing some gate-control theory pain suppression. But, for me, the key feature is the automated injection. I never thought this was a necessary feature. But I like not having to maintain a slow injection rate, especially in the maxillary anterior. I never realized how tiring this was until I let the computer take control, and all I had to do was hold the syringe in place!

Dr. Michael DiTolla is director of clinical research and education at Glidewell Labs in Newport Beach, Calif., where he also teaches courses on topics such as esthetic and restorative dentistry. He teaches a two-day, live-patient, hands-on laser-training course that emphasizes diode and erbium lasers. He also teaches a two-day, hands-on digital photography course on intraoral and portrait photography, and image manipulation. For more information on these courses, e-mail Dr. DiTolla at [email protected] or call (888) 535-1289.