Long Term Opioid Use and Dental Local Anesthesia

Norco opioid pain medication used by dentists

Norco – a common opioid pain medication

As a dentist in a busy private practice, I am constantly doing dentistry, which involves injections of local anesthesia. I have blogged previously about certain circumstances in which it can be difficult to get a patient numb (those are located here and here). But an increasingly common phenomenon involves difficulty in getting patients numb who are long time users of opioids (often called narcotics).

A common situation is a patient with chronic pain who has been taking an opioid type painkiller long term (such as Percocet, Oxycodone, Oxycontin, etc.). A dental procedure that requires effective local anesthesia is attempted on that patient. During the procedure, it is learned rather quickly that the patient is having difficulty either getting numb and/or staying numb.

Opioids, Narcotics, Pain Pills, Etc.

The term opioid is derived from the word opium, which is a component of the opium poppy. The raw opium can be processed to produce morphine or heroin – both of which are powerful pain relievers. The term opioid simply means a medication that acts on the opioid receptor.

Opium poppy, the basis for narcotics

The opium poppy – the flower from which morphine and heroin are derived. Image courtesy wikipedia.

Millions of Americans take opioids for both acute and chronic pain. For those individuals who take them chronic pain, a tolerance will develop, requiring larger doses. Large doses of opioids taken over time can lead to many long term effects. Many of those effects – constipation, dry mouth, etc. – are well documented. What is not well documented nor well researched is how long term use impacts the effectiveness of local anesthesia.

Long Term Opioid Use and Dental Local Anesthesia

Unfortunately, there is very little “official” information available for practicing dentists and dental students on which to rely. The most widely read and cited textbook on local anesthesia for dentists – A Handbook of Local Anesthesia – by Dr. Stanley Malamed – makes no mention of this phenomenon.

Lidocaine is less effective in opioid users.

Multiple studies have shown lidocaine is less effective in opioid users.

However, a survey of recent research has shown multiple articles which directly and/or indirectly give support to this phenomenon:

  • In this article, opium abusers were compared to non-abusers in their response to lidocaine (lidocaine has replaced novocaine as the local anesthetic of choice in dentistry). The abusers were found to require a longer amount of time for the lidocaine to work. And in addition, a greater amount of lidocaine was required.
  • In this study involving rats, the administration of morphine (an opioid) resulted in a decrease in the potency of lidocaine.
  • In another study involving opium vs. non opium users, chronic users experienced a shorter duration of local anesthesia than non users.

In fact, there is a specific term for a related phenomenon, which is Opioid Induced Hyperalgesia. Basically, those individuals who are chronic users can become MORE sensitive to painful stimuli.

However, despite all of these studies, there remains to be seen a widely accepted theory for a mechanism behind the local anesthesia resistance seen in these individuals.

What This Means for Dental Patients

As with most dental issues and concerns, the most important thing is to make sure your dentist is aware of your history. This can and should include any history of any and all use of prescribed and recreational drug use.

Will it be possible for you to get completely numb? There is no way to know for sure – each and every person is unique. However, if your dentist is aware of your history, then it is much more likely that the best approach(es) can be taken.

 

The Palatal Injection: Dentistry’s Most Painful Shot

Probably the most frequently commented upon topic on this blog involves what the majority of patients dread the most: the shot. As a result, I’ve posted many articles related to dental injections, including articles on novocaine (no, we don’t use it anymore), epinephrine (the racing heart does not mean you are allergic to it), why some people/teeth are hard to get numb (over ten different reasons), etc.

I’ve also done a two part series on what factors cause some dental injections to hurt more than others (located here and here). However, given the number of comments and questions about palatal injections, it was warranted to create an individual post on what can be considered dentistry’s most painful injection.

What is a Palatal Injection?

This may seem somewhat obvious but it is worth explaining. We’ll start with a photo.

palatal injection photo - most painful dental shot

Injection into the palate on the right side. If it looks painful, it’s because it is painful.

In a palatal injection, local anesthetic is injected into the soft tissue covering the hard palate, just adjacent to the tooth/teeth to be worked upon. It is not an injection into the soft palate nor the uvula. And it is only done for top teeth.

These types of injections are performed when you need the gum tissue on the roof of the mouth to be numb and/or when the procedure requires the tooth to be super numb (like an extraction or root canal). In my experience, for most fillings of upper teeth, palatal injections are NOT needed.

Why Palatal Injections Hurt so Darn Much!

There are two major reasons to explain why these hurt so much:

Tightness/Density – the tissue lining the hard palate is very dense and tight. There’s no “give” to it. The needle initially goes in and is accompanied by a pinch. That pinch is actually not the worst part. The worst part is when the local anesthetic fluid is forced in. There’s literally no room for it because the tissue is so dense. That forcible entry of fluid into this tissue is what causes the pain.

Topical anesthetic does not help with palatal injections

Traditional topical anesthetic does little to help with palatal injections.

Want an analogy? Imagine you have a turkey baster injector. Plunge the injector deep into the breast or thigh. Then try to inject. It will take GREAT force to get even a little fluid into this dense muscle. This is like a palatal injection. Next, move the tip of baster until it is just at the border of the thigh and skin. Then try to inject. There is little to no resistance. Fluid goes in with great ease, taking advantage of the looseness at the skin/muscle junction. This is like most other dental injections.

Traditional Topical Anesthetic Doesn’t Work Well – traditional topical anesthetic, a.k.a numbing jelly, doesn’t penetrate the tissue very easily, regardless of how long you wait. As a result, it exerts little to no effect, thus offering little to no pain relief.

How Palatal Injection Pain Can be Reduced

Fortunately, there are ways to reduce the pain associated with palatal injections. Note, however, that these are all done by the dentist himself/herself (except the last one which involves both dentist and patient).

  1. cotton applicator applying pressure can reduce pain of injection on the palate

    Application of pressure can reduce the pain.

    Waiting – in nearly all cases, if you are going to get an injection on the palate, you will also receive an injection on the cheek side. In many cases, if the dentist waits 10 minutes or so after the “cheek side” injection, some of that local anesthetic will work its way over and partially anesthetize the palate. This will make it so that the palatal injection is less painful.

  2. Pressure – placing firm pressure with a cotton applicator for at 30 seconds can slightly numb or obtund the pain sensation. The pressure is applied on the roof of the mouth right where the injection is going to go.
  3. Super Topical Anesthesia – some dentists will use a pharmacy compounded topical anesthetic that is several times more powerful than traditional topical. Using this correctly can also reduced the pain.
  4. Cold – application of a cold cotton applicator with pressure right before the injection can also reduce the sensation.
  5. Sedation – if you are sedated, you are unlikely to even feel the painful injection, let alone remember it. Sedation dentistry is very effective – I do it routinely in my office.

Not all dentists employ the above techniques. But all dentists are aware of the painful nature of this injection and do their best to only do it when necessary.

 

Don’t Shock Me Bro!

As a dentist in private practice, I administer local anesthesia routinely. Or, in layman’s terms, I give numbing shots daily. That’s just two ways of saying the same thing!

Dental local anesthesia infiltration photo where no electric shock will occur

This type of injection is highly unlikely to give you an electric shock sensation

Occasionally, when I am doing certain injections (and note that there are different types of injections that dentists administer – more on that later), the patient will experience an electric shock sensation originating from the injection area. This ends up being quite a shock to the patient (pun intended) with me then subsequently spending significant time explaining why/what happened.

In addition to seeing this happen periodically in my own office, I get tons of comments and inquires on this blog about “the electric shock they got” from the dentist’s needle. Since nearly all of my articles are either about my own experiences – or from inquires I get on this blog – I decided it was time to do a post on this phenomenon.

Infiltrations versus Nerve Blocks

To understand why the electric shock occurs, a little background information is needed.

Femoral nerve block with an ultrasound

A nerve block guided by ultrasound being done by an Anesthesiologist.

In medicine – and I do consider dentistry to fall under the medical umbrella – there are various techniques for numbing a particular anatomical region. An infiltration is when local anesthetic is deposited directly adjacent to the site to be worked upon. In these cases, the local anesthetic works by affecting tiny, microscopic nerve endings that almost resemble a spider web.

In contrast, with a nerve block, the local anesthetic is deposited adjacent to a large branch of a nerve. This ends up numbing everything that the nerve supplies downstream from the area the anesthetic was administered.

To use an analogy: picture a tree. An infiltration is where anesthetic is placed next to a single leaf. A nerve block is when the anesthetic is placed next to a large branch close to where it is coming off the trunk.

Shock and Awe

When it does occur, the electric shock phenomenon is nearly always associated with a nerve block (as opposed to an infiltration). Why does this occur?

The shock sensation is believed to occur when the needle makes contact with part of the nerve trunk (sources: here, here, and here). The needle basically enters the tissue, touches the actual nerve, and the trauma from that immediate contact provokes a signal that your nervous system perceives and interprets as an electric shock feeling.

photo of needle and skull bone where you give a dental nerve block

In a mandibular nerve block, the needle is aimed right where a large nerve trunk (the inferior alveolar nerve) is about to enter the lower jaw (the mandible)

Some key facts:

  • The incidence of this occurring is between 1.3% to 8% of the time for mandibular nerve blocks (the large difference is based on different sample sizes).
  • Studies have shown that an electric shock sensation does not place the patient in a higher risk category for permanent nerve injury.
  • The most commonly involved nerve is the lingual nerve (which will give rise to a shock sensation in the tongue on the affected side.

As you can see, since the origin of the electric shock is contact with a nerve trunk, it is nearly impossible for this to occur with an infiltration.

What to Do if You Feel the Electric Shock?

With dentists administering millions of injections per year, this occurs on a regular basis throughout the world. Keep in mind:

bullseye showing that electric shock is due to hitting the nerve

An electric shock means your dentist hit a bullseye.

  1. Although the feeling was unpleasant and unexpected, the research clearly shows that this does not place you at a higher risk for permanent nerve issues (see bullet point #2 above).
  2. In many times, you get numb extremely quickly.
  3. This happens to all dentists periodically and this phenomenon alone does not mean your dentist is unqualified or negligent.

Since this occurs when the needle makes contact with the nerve trunk, it means your dentist was dead on with his/her aim. So, if you like, you can congratulate him/her on hitting a bulls-eye! Or, just understand that the human anatomy is unpredictable, and sometimes things like this happen.

Note: the sources used for this post are listed above and are also based on my own experiences. Note that I cannot answer emails to me asking for dental advice. The title for this post is based on the “Don’t Tase me Bro” incident and I have no relationship with Mr. Meyer. This post should not be construed as me providing commentary on that incident.

Dental MythBuster #14: A Swollen Lip After a Dental Visit Means You’re Allergic to Novocaine

This is one dental myth that every dentist has to deal with at some point. And that is the myth that if a child’s lip swells up after a dental visit where local anesthetic was used, it always means the child must be allergic to something the dentist injected.

And to make matters worse, this myth is then often propagated by the child’s pediatrician.

What would you think if you saw this the day after your 8 year old got a filling on his lower right molar:

swollen lip from biting while numb after filliing

Lower right lip swollen after a filling was done on the lower right.

That looks pretty nasty right? Something clearly happened here. In my own experience, and in talking to other dentists, parents generally do one of four things upon seeing this:

  1. Parent immediately heads to the closest ER or emergency walk-in clinic.
  2. Parent immediately calls the pediatrician for an emergency appointment and is seen that day.
  3. Parent gets on Google, becomes almost immediately convinced of an incredibly dire situation, and then does either #1 or #2.
  4. Parent calls the dentist office.

Wouldn’t it make sense to call the dentist office? After all, it was the dentist who did the procedure, wouldn’t he/she know what is going on?

But unfortunately, options 1, 2, and 3 are often pursued. And in many of those cases, an incorrect diagnosis is frequently made, which leads to unnecessary finger pointing, as well as wasted time, confusion, and missed school for the child.

So, what does it mean when the lip swells up after a dental appointment when local anesthetic was used?

Swollen Lip = Lip Biting While Numb (99.99% of the time)

Here are two cases I’ve seen in my office:

swollen lip after dental work means lip biting

Swollen lips after dental work. Both patients admitted that they inadvertently bit and/or played with their lips while numb.

The above photos look unpleasant, right? In both cases, lower teeth were given local anesthesia, and that numbness extended to the lip. And in both examples, the patients admitted to repeatedly biting their lip.

The repeated biting led to swelling, bleeding, and bruising. Many times, the child has no recollection of doing it, because the child was numb and felt no pain. But the next day – whoa!

It is quite easy to see how this can come from biting. Go ahead and try to bit your lower right lip with your upper front teeth. Easy, right? Do this a couple of times very hard while you’re numb and you’ll end up looking like the one of the photos.

Why This is not an Allergy

Despite seeing this on a regular basis, many dentists (myself included) still have to deal with accusations and/or false diagnoses of allergies from the injection. Here are some key points:

  • Location. The injection site is nearly always located far away from the traumatized area – in some cases nearly two inches. If it were an allergy, why then is the injection site totally normal? See the photo below.
  • Appearance. In general, allergic reactions do not produce a localized ulcerated area away from the injection of the alleged allergen. The appearance of this is simply not consistent with an allergic reaction.
  • Lack of Systemic Symptoms. Even less severe allergic reactions will produce other symptoms such as dry mouth, hives, and other findings. None of these are typically present in lip biting.
dental injection photo next to tooth

Dental injection adjacent to a 12 year molar. How could this produce an “allergic” reaction on the lip only when the injection site is so far away?

Of course, allergic reactions can occur from the injection. However, they are exceedingly rare, and don’t present like this. For more information, see this three part series.

What Should You Do?

So, if you or your child’s lip is swollen after receiving local anesthetic, what should you do? Call your dentist. Generally speaking, pediatricians, PAs, and NPs do not have experience seeing these types of things, and then come up with what we call “creative diagnoses” which are usually incorrect. General dentists and pediatric dentists see lip biting all the time and can guide you on how to handle it.

But to stress this point, it is a myth that a swollen lip (in the absence of other findings) after a dental visit means you are allergic to lidocaine (mistakenly called novocaine).

Until the next dental myth is busted…