Observations about BFPDL

I can say with confidence that a BFPDL can be given with little or no pain.

Pressure vs. Speed

It has finally occurred to me that "slow" is an inadequate adjective for describing the technique. A much better term would be "low pressure". It is true that a slow injection is a frequent accompaniment to a low pressure injection but it is the low pressure aspect of the BFPDL injection that causes it to be both painless and effective.

Let's think about what is happening when we give such an injection………

Have you ever inserted a needle into some attached gingiva, injected for a bit and then decided, for whatever reason, to withdraw your needle and insert it again in close approximation to the first needle puncture site and injected again? Of course; we dentists all experience the same things over time.

What happens? When injecting into the second site, the flow of anesthesia under pressure from the tremendous mechanical advantage your syringe allows, finds its way into the first puncture and comes shooting back out of it like a squirt gun. If you are not careful, you can just about get hit in the eye with such a stream of anesthesia. What do you do when this happens? If you're like me, you simply duck the stream and inject a little harder, keeping your fingers crossed hoping that enough of the anesthesia makes its way in to have an effect. Or, you poke a third hole and now have two streams flowing back at you.

What can we learn from this? The first thing is this; if a stream of anesthesia is shooting back at you, there is little or no anesthesia that is staying in the patient. The other thing is that the tissue must be very dense in order for such a small hole to act as an exit port for the anesthesia to squirt back through at you.

Let's consider a few other things first and then see if we can come up with some conclusions.

Consider the speed of the injection; if you are in loose alveolar mucosa (which is full of stretchy elastin fibers) a given amount of pressure on the syringe plunger will result in a relatively quick injection. If you are in dense collagen, such as the palate, a given amount of pressure will result in a much slower injection (relatively).

So the speed of the injection varies in proportion to the density of the tissue. The denser the tissue, the slower the injection.

I have been in tissue that is so sense that it seems like my syringe is stuck and not making progress. What we intuitively do when we encounter this situation is squeeze harder on the syringe barrel with the mistaken belief that it is necessary for us to "feel" the anesthesia going in and also to make sure that we get a good dose if it to go. In fact, this is not true. It only takes a very small amount of anesthesia to make this technique work, and it must be administered under high enough pressure to make its way into the tissue, but not pressure that is high enough to rupture and injure tissue.

What we know

We already know a few things about the BFPDL injection technique.

1. Some dentists have amazing success with it.
2. Other dentists are abject failures at it.
3. Some dentists have patients who experience the possible side effects of the technique: post-op pain, and less frequently, necrosis, on a regular basis.
4. Some can give it with little to no pain consistently.
5. Others create pain when giving it.
6. Those who succeed claim that it must be given slowly.
7. Successful dentists claim that the patient response is overwhelmingly positive to an extent that is rarely experienced.

Here are a few conclusions that I have made while observing many dentists over time in my hands-on workshop.

Perception vs. Reality

A very large percentage of general dentists, in fact, the majority of GD's are incredibly heavy handed. Even when admonished, they just cannot help themselves. Recidivism is the rule, even when having some initial success; before long, they simply revert back to their old habits and then wonder why they just can't seem to make the technique work for themselves. It's easy to become frustrated with the technique when this happens.

This is a natural human trait and should, in no way, be seen as a criticism. On the other hand, it should be recognized. It is only through recognition of this phenomenon that true change can be allowed to take root and flourish.

The Consequences of a High Pressure Injection

High Pressure to tissue, injures tissue. It is responsible for necrosis, paresthesia and pain. After all, pain is a warning of tissue injury. Tissue injury is often caused by high pressure over a short time span.

Connective tissue is ruptured, cell injury and cell death result. Histamine release occurs, etc.

The average dentist (including myself in the past), is to lean on the syringe up to the point where the carpule actually bursts inside of the syringe barrel.

The dentist is interested in delivering a bolus of anesthesia. He is in a hurry. Since time is relative, the dentist thinks that he is saving time by giving a block, which is fairly quick, and then moving to the next op. In fact, once a dentist leaves an operatory, any number of time delays can occur not-with-standing the transit time, hand-washing and glove change. Conversations, forgetfulness, etc. may occur. Greetings, observations of points of etiquette, reviewing treatment and x-rays, etc. must all occur. Repositioning your chair, focusing on the tooth, retooling, etc.

Time slows down when you are giving a long injection. What takes a mere two minutes, instead seems like it takes forever. The beauty of these higher pressure (but not too high of a pressure) injections is, that they are incredibly efficient when compared to the alternative chair-hopping paradigm. On average, the time spent attaining anesthesia is a fraction of what block anesthesia is.

What I have Observed Over Time

I've been fortunate enough to be able to observe quite a few things first hand when it comes to the behavior of dentists since I instruct dentists on a regular basis here in Houston. It's given me some insight and perspective on the behavior of dentists.

A big part of what I teach is endo. I use endo as an example of heavy handedness because it is easy for me to directly observe the force and length of time the typical dentist will apply to a file in a canal. The average dentist is heavy handed, IMO. They drive the file in the canal and leave it there too long. To me that's very scary because I know that the likelihood of file breakage is high; in fact it is inevitable.

The same is true with injections. The average dentist is putting too much force on the trigger of his or her PDL syringe because it is not real to them just how slow the injection needs to be together with the fact that they are in a hurry and feel the need to get going at all costs. The perception of time varies wildly.

Consider the typical argument with your wife over your time getting home. She will round off to the nearest half hour or fifteen minute increment in her favor, you will round off time in your favor. It is a natural human instinct. We are all egocentric to a degree (hopefully short of being sociopathic). If you average the two times, it will usually come out close to the true time (all-be-it slightly in favor of the wife's point of view, on average).

There is a distortion of the element of time in the mind of the general dentist.

The Cortical Plate

The cortical plate is thin in the area of the interproximal area. This is easy to demonstrate; the next time you have the opportunity to anesthetize a tooth that is next to an edentulous area in the mandible, give an intra-osseous injection directly on top of the ridge. You will find that it is very easy to penetrate the cortical plate in this area.

Now consider this; the cortical plate is very thin in the area between two adjacent teeth even when there is not an edentulous area. If you penetrate the interdental papilla with a short needle in a PDL type syringe and drive the needle into the col area so that the needle lands directly into the bone at the nadir of the col, and you apply pressure, it is sometimes possible to penetrate the cortical plate to a degree. In any case, it is usually possible to gain good back-pressure in this area. Now, inject very slowly. You will achieve good anesthesia from this injection and you will achieve anesthesia on two teeth.

When giving a standard BFPDL, many ask me if it is necessary to give an injection lingually as well. The answer is no (the vast majority of the time). The anesthesia penetrates quite readily to include the tissue lingually even from a buccal injection.

A PDL technique and even a col injection are both, almost certainly, an intra-osseous technique since the anesthesia flows through the highly vascular medullary bone making its way down to the apical foramen where the nervous tissue and vascular system supply the tooth. There have been a few studies performed with dye that show this to be the case.

An Efficient Beginner's Strategy

If I was just starting out and I wanted to master this technique, I would begin with a block and then start with a BFPDL and then proceed to a col injection technique. You're going to be able to give a block over a period of time of one minute, a BFPDL takes about two minutes. A col technique takes about another two minutes. If the BFPDL technique is successful, you are able to begin your procedure without leaving the chair in about three minutes without the col injection and about five minutes with the col injection, which beats the socks off of a block technique in terms of time of onset of profound anesthesia.

You gain not only the time that you would have spent by a longer injection but also all the time that is typically lost with a block injection technique.

So here are some succinct conclusions:

1. Many times, dentists think they are giving slow injections when in reality they are not.

2. The injection is based on pressure more than it is based on speed.

3. When in dense collagen, the speed is almost certainly slow.

4. Resistance created by a stuck plunger needs to be obviated by injecting a drop or two of anesthesia before you start the injection, otherwise you will not be able to differentiate between resistance to the injection site itself and the added resistance of a stuck rubber plunger.

5. You may inject into the col area.

6. It is not the amount of anesthesia emptied out of the syringe that counts, it is the amount of anesthesia that enters the tissue and stays there that counts.

7. You may inject in the LFPDL. Many claim better results when injecting here than when using the BFPDL.

Here's my advice. Don't give up on this technique. Of all the efficiencies I have written about, developed or improved, rapid, predictable, painless anesthesia is the most critical of all for the efficient dentist.

You have much to gain by mastering this technique.