Local anesthetic news

  While dentistry continues to shed its old image and like the beautiful peony flower of spring which faithfully reminds us that like the tiny chicken pecks an exit through its shell to freedom, we too shall soon be shedding our cashmere coats and boots to behold endless fields of sheer beauty as spring transitions into summer.

Oral sciences, historically strut their new technologies at their largest shows in the spring each year in Cologne, Germany and
Chicago, Illinois. Dentistry is benefiting tremendously from world wide research and innovative minds.

When was the last time while walking the corridors of a dental/medical building have you heard that shrilling or the blasting burr from a dental drill? Most such procedures are now taken care by laser. It took a little while, but for the records it was Einstein’s law of Relativity and his work on the speed of light showed that gravity had the ability to bend light. That was the beginning of the laser beam.

It is probably more likely to hear waterfalls and to sense the aroma of Asian or Tropical fragrances seeping from dental offices as more and more dentists offer through third parties a “day” of indulging oneself in the spa or a total therapeutic massage work out. 

However there are time when it is necessary to administer pharmaceutical agents (drugs) during dental treatment. The first that comes to mind is the placement of a local anesthetic solution to disguise or numb the presence of pain. It is not unusual for patients to have a low threshold and may manifest a mild allergic hypersensitivity to this solution. At other times such reactions can be as a result of too rapid [ injection should take 45 – 60 seconds ] an injection and finally, a tiny bit of the solution may enter into the vascular system during administration which may cause a faint or light headed feeling.

Most anesthetic solutions do contain epinephrine, the main purpose of which, is to reduce bleeding and to constrict or retain the anesthetic solution in place for a longer period. It is more preferable to have a little numbness persisting after the procedure, than to have the patient regain sensitivity before the work is finished. At times during a lengthy procedure the patient may require a second injection.

The purpose of this article is to draw your attention to an the following article published and referenced under JADA (Journal of American Dental Association) which deals with epinephrine-impregnated retraction cords. 

Epinephrine acts as a vasoconstrictor when used in dental procedures; however it can act as a vasodilator if it is introduced intravascularly or systemically absorbed. Caution is advised when relative high concentration of epinephrine is impregnated into retraction cords. Please consult your dentist. 

DENTAL PRODUCT SPOTLIGHT

Gingival retraction Controlling blood, crevicular fluid, water and saliva while taking impressions is critical. Water and saliva can be controlled by air spray. Blood and crevicular fluid can be controlled by retraction cords, hemostatic agents, electrosurgery or rotary gingival curettage.¹ Retraction cords displace gingival tissue mechanically; they also can have a chemical action when impregnated with astringents and vasoconstrictors that cause tissue contraction and hemostasis. Electrosurgery creates a trough around the tooth by removing superficial cell layers from the gingival sulcus’ inner lining through application of an electric current. Rotary gingival curettage removes the sulcular epithelium with a high-speed diamond bur. Azzi and colleagues² studied the effect of retraction cords, electrosurgery and rotary gingival curettage on gingival recession and loss of attachment in dogs. They found that cords had the smallest effect on the gingiva and rotary curettage had the largest effect. Astringents impregnated in retraction cords include aluminum chloride, ferric sulfate, alum (potassium aluminum sulfate) and zinc chloride. Alum and ferric sulfate may be irritating and even corrosive at high concentrations, while increased concentrations of zinc chloride may damage bone and tissue permanently.³ The least irritating cords contain buffered aluminum chloride, which may be left in the sulcus for up to 15 minutes without permanent damage.⁴ Weir and Williams⁵ reported that soaking retraction cords in aluminum chloride solution enhances hemostasis. This led Runyan and colleagues¹ to study whether soaking cords in aluminum chloride solution has any effect on the ability of the cord to absorb moisture. They found that presoaking had no effect on fluid absorption and, therefore, may be a worthwhile adjunct. Gingival retraction cords containing epinephrine effectively control bleeding; however, from 24 to 92 percent of the epinephrine may be absorbed systemically.⁶ Epinephrine-impregnated retraction cord contains 8 percent racemic epinephrine. One study estimated the concentration of epinephrine absorbed systemically to be equivalent to approximately 3.9 cartridges of local anesthetic containing 1:100,000 l-epinephrine.⁷ This estimate is considerably lower than previous estimates because the authors calculated the actual amount of releasable epinephrine in the cord before retraction, which was found to be approximately one-half that of the labeled amount; based their final estimate on the more biologically active l-epinephrine; and found that presoaking in aluminum chloride removed approximately 25 percent of the racemic epinephrine in the cord. There are conflicting reports on whether epinephrine absorbed from retraction cords has any adverse physiological effects.^7–11 The potential epinephrine reactions that can occur following systemic absorption include increased anxiety after cord placement, limb tremor, diaphoresis, headache, florid appearance, tachycardia and elevated blood pressure.⁶ However, there are many variables that make it difficult to predict the physiological effect. These variables include the concentration of epinephrine absorbed from the cord; the length of time the cord is in the sulcus; the condition of the gingival tissue; the presence of crevicular fluid or saliva; individual patient response; and drug interactions with tricyclic antidepressants, nonselective ß-adrenergic antagonists, certain general anesthetics and cocaine.^10,11 Therefore, recommendations have been made to either limit or avoid use of such epinephrine-impregnated retraction cords.^7,10,11comments to author.  mailto:localanesthetics@yahoo.ca    M.Sc. PharmD. CCPE   WWW.Anestheticnews.com

This is my confession. I am a twenty four year old female of average build. I run five kilometers every day and I alpine ski in the winter. I watch what I eat and would consider myself to be in good shape. However; I do have one vice which is the reason for my confession. My dental work has been fairly extensive over the years, but I have an excellent insurance plan. The work was being done on my upper right where there is a bridge. The bridge was failing hence the need for a dental assessment and treatment. On this visit I was given two shots of anesthetic within a half hour. Each shot was expelled in about 15 to 20 seconds. Through the over head monitor I could see the blanching (gum lost the pink color. It was now white). I should add this was not a store top office. This Dental Practice in which every aspect of its facilities had been intentionally designed to reflect a much more relaxed, serene and contemporary environment for the well-off patient was located in a medical building. It was outfitted with the latest toys and computerized gadgets. It was like the cockpit of an Airbus 380. At a guess I would put my dentist to be in his middle forties and to me he looked and conducted himself every bit of a successful and up-to-date dentist.

This is my confession. As a patient, on my dental visits, I want the dentist to be current on all techniques of administering the anesthetic within reason, to make my visit a pain free experience. My choice of words is deliberate because I do not want to be heavily sedated. Drugs may control fear and anxiety, but do not fully control pain. And furthermore it is said they can cause confusion and/or respiratory depression. I am also aware that sedative drugs can stay in your system for two to three days after ingestion.  Neither do I want the application of nitrous “laughing gas” since there appears to be some ambiguity surrounding the duration of how long one should be under this application. Furthermore how can I tell the scavenger system has not exceeded its service date? However having said that, I am aware that all clinicians practice to the best of their ability and are not cavalier and will not knowingly push the envelope which could cause harm to their patients. However we have heard of situations which could have been avoided. Shift does happen.   

This is my confession. After each shot he excused himself while he went to another operatory. He was darting from room to room and between taking telephone calls he was reviewing the work of his hygienist. He was busier than a one armed paper hanger. I felt somewhat neglected like an infant left imprisoned in a crib. Even the assistant left the room. I was lonely. I thought how nice it would be to climb out of the chair and stroll around the room and indulge. As I mentioned I have had above average dental work over and above regular cleaning of tartar during my college days and still do. I knew a sudden rise from the supine position would be more foreboding than the painful shots which I suffered through. Deep within me, I knew some thing had gone a rye more so on this particular appointment. After each shot the pain grew exponentially. My tissue felt expanded and throbbing. I felt the tingling and had no control of my drooling but I was not frozen. Prior to my visit I had searched the internet which said that local anesthetics are used to control regional pain through their ability to block sensitivity by preventing sodium transport across the nerve. They also mentioned that failure to block that action potential was possible either through anatomical reasons or operator errors and skill. Who am I to delve into my oral anatomical variances? I am Caucasian and my mouth does not appear to be different from people of my build. Furthermore on previous occasions I was completely frozen where the procedure was completed successfully and painlessly.

This is my confession. During one period when I was left alone as he darted to another room, my upper right jaw felt just like it was about to explode, I overheard a one sided conversation between my dentist and someone else who I guessed was also a dentist. The letters A.M.S.A. (which) meant nothing to me were as clear as a bell and for some strange reason I paid attention as a sixth sense completely took control of my very being. These letters were scorched into my memory. The constant in and out of the room where I sat and a quick probe, suddenly confirmed that something was not going according to plan. As I said, I could only hear one side of the conversation but the sweat and the look on his face spoke a thousand words. Together with the tightness and throbbing dull pain confirmed he was conferring with a colleague. I distinctly overheard the  letters A.M.S.A…silence…followed by the phrase “a regular syringe.”… Silence…then the word “twice”. Ah! Yes the conversation was about me. There was a problem.

This is my confession. A few moments of silence, then he entered without his assistant and his face said it all. As he sat and with his heels rolled his stool towards me, he reached up and turned on the overhead halogen light while focusing it at me. Not a word was spoken but this automatically prompted me to open my mouth. He probed with his gloved finger and a miniature reflector or mirror for about 5 seconds but which felt like 10 minutes. He lifted his anti splatter orange transparent eye shades and said. “I am going to refer you to a specialist friend of mine”. The bib around my neck was unclipped and he gently assisted me out of the chair. His sincerity was cloned over his face and his shoulders drooped like tender tulips on a hot day. “It will be about a week to ten days, in the mean time I will order a prescription for Ibuprofen 400 mg to be taken twice a day with a meal.” His saddened tone was strict orders that I should call him if the throbbing still persisted.

This is my confession. When I finally got home I instantly took one ibuprofen with a glass of milk because I had no appetite and the interior of my palate was too sore to chew on food anyway. I had some Tylenol and together with the Ibuprofen, I made it through the night. The letters A.M.S.A still hounded me like a puppy following my footsteps. I anxiously wanted to see what Google had to say. Wow…there were sites upon sites that discussed this technical term and there I was before my laptop like a misfit in dental school doing oral anatomy 101. However after half an hour of reading dental clinical studies, I managed to get the acronym for A.M.S.A.  To explain it would achieve nothing since it describes a special type of injection used on the upper jaw. It is apparently one of the most difficult injections to master and one of the articles suggested that it was more effectively done slowly through some sort of computerized delivery system. Why did he not have that gadget? After all, to me his operatories lacked for nothing. The dull pain was still apparent but kept under control by the pills. Could I dare have a peep at it? I was nervous and scared. I took the challenge and what I saw was gross. I immediately called his office and left a message. My call was returned at about 8:32 AM. I explained what I had seen and he calmed me by identifying the condition as palatal necrosis, which meant nothing to me. He continued; “because of the mouth is rich with a strong blood supply, together with the anti inflammatory drugs, healing will be rapid.” My dentist has a calming voice and I felt somewhat more at ease.

Now here is my confession. During my college days I would occasionally have a toke of marijuana with my friends. It is not a big deal and I still have one every now and then especially if I am anxious or apprehensive over some event. I frequently used the internet and Facebook like all young people of my age and social lifestyle. It was during my search I read that marijuana has been shown to increase the activity of liver enzymes. It so happens that local anesthetics are broken down by the liver. Is this why I was not fully frozen? Or was it one of William Shakespeare’s Comedy of Errors being played out for me. What a coincidence!  An A.M.S.A technique which is difficult at the best of times being performed on a patient who did marijuana an hour before my dental appointment!

The contents of this mail was received by this author. I contemplated for quite some time whether I should post it. As I write, the outcome was never revealed to me. There was nothing through which it could be identified. I therefore opted to post it for what it is worth. However as a pharmacist I would qualify this as “a case of one” due to non clinical input and from one side only. However it is interesting to note a few points.

Comments to author. mailto:localanesthetics@yahoo.ca   M.Sc. PharmD. CCPE  

Please visit WWW.AnestheticsNews.com       http://tinyurl.com/2bsqsz

When did this all happen? To my astonishment there were Toto toilets and a spa? This has got to be one of the best kept secrets…WOW!  Times were when your twice a year visits to the dentist were the most nerve shattering and fearful experiences with which one had to endure. Just to look at the red asterisk on my calendar followed by Dr. Watson, automatically drove up my blood pressure.

Recently I developed an acute pain in my lower right jaw and had to get to the dentist in a hurry. Yes! the diagnosis was a seriously infected molar and a root canal, AKA,  an endodontic procedure had to be performed ASAP. I must admit I had not been getting regular check ups, so I had no one to blame but myself. A few painkillers kept me through the night until my appointment the next morning.

When I arrived for my appointment, feeling less pain because of the painkillers, I noticed the office in greater detail. The Italian leather couches, slate tile floors and backlit etched glass in the Patient Lounge, exuded a definite warmth and elegant atmosphere. My endodontist was considered to be one of the best, hence the ambience to go with his status.

I was taken into a room with soft music and current magazines like Ophra, Vogue, Sports Illustrated, all appeared to have been delivered that very morning. I thought to myself, “where have I been”?  The dentist greeted me and after some small talk, asked me to place a tiny pill under my tongue which he explained would dissolve in a few minutes. His assistant returned in about half an hour and led me into the operatory. By this time I was feeling very relaxed and comfortable.

The local anesthetic solution was delivered through a computer-like electric tooth brush (minus the brush tip) and I felt absolutely nothing…no stick, not anything. I felt very relaxed throughout the procedure. When he was finished about one hour later, all I felt was a tiny residue of the anesthetic but was quite awake without any pain.I was escorted back to the ante room and relaxed with a magazine for about 15 minutes.

Here is where the surprise and fun started.This Dental Practice in which every aspect of its facilities had been intentionally designed to reflect a much more relaxed, serene and contemporary environment for the patient and which incorporated both a series of Dental Spa like services as well as Non-Dental Spa Services was extremely well planned. The more traditional Spa services such as massage, manicures, facials and pedicures was performed in a dedicated, private Spa Treatment room separate from the rest of the clinic.

I had written the day off because I knew I would be in no condition to return to work. I was offered a complementary spa-like services which included a wide variety of treatments and services. It was as if I had entered into the 22^nd century. I walked out of that office feeling like a million dollars. This experience has stayed with me ever since.  I have been told that such facilities are quite the trend even in small towns. I have already booked my follow up appointment, this time the asterisk is in Green. Comments to localanesthetics@yahoo.ca 

Author: M.Sc. PharmD. (patient’s story on file).        

Dr. Watson reviewed his technique. “How could this be”?  Am I loosing my touch? Have you ever been told by your dentist, “Gee! I seem to be off today! I cannot get you fully frozen”. There are many techniques to deposit local anesthetic into the oral cavity (tissue of the mouth) however, for this discussion; I will only deal with two basic modes, namely infiltration and complete nerve block.

Infiltration allows the dentist to freeze one or two teeth at one sitting, whereas the nerve block freezes a complete quadrant. For dental purposes the mouth is divided into four quadrants, to facilitate the numbering (of the teeth) process. Whether one is given an infiltration or a block, the desired expectation for the dentist is the same. He/she needs to be able to complete the procedure without the patient feeling no more than the initial gloved fingers of the dentist. In other words, that area of the patient’s mouth should feel like a piece of log. It is referred to as the “wooden effect” and dentists call this “class A” anesthesia.

However, according to all textbooks on dental anesthesia, failure is generally accepted to be around 15%. There are some 15 to 18 people out of 100 who will still have residual sensation, or in other words, will experience some discomfort and or pain. When this situation occurs, dentists will chat among themselves as to the reason(s) why. Discussion of marijuana comes later in the text.

There are many reasons listed, ranging from a bad batch of anesthetic solution to persons who may be classified as having accessory innervations. There could also be patients with anatomical variations, such as a wide flaring mandible and furthermore, the explanations could be an infection within the gum tissue. There are several more reasons, for example too rapid a delivery of the solution, or even an over anxious patient. These all add up to give us that 15% failure.

However, our changing lifestyles and habits are beginning to become a thorn in the sides of dentists. The growing use of cannabis…known on the street as marijuana, is being associated with the inability to achieve local anesthesia in some patients. The duration of action of local anesthetics depends primarily on the redistribution of the drug away from the site of action. This redistribution can be altered by several factors, some of which also influence onset. These considerations include diffusion away from the site, concentration, lipid solubility and protein binding qualities. This recreational habit is no longer an experimental phase of a growing youngster. It is now widespread among all walks of society.

Dentists have never had to deal with this variable factor back in the sixties and seventies. However, before he/she starts the “marinating” process, this is when the dentist deposits several different brands of anesthetic solution in numerousAreas of the mouth, hoping to strike luck. But this luck is seldom present. There is a small window with which the dentist has to play. If anesthesia is not apparent within that time, then the tissue has become too acidic and another attempt can be made later when the pH of the tissue has settled down somewhat.

Patients using cocaine should allow at lease twenty four hours, if a dental visit would involve the use of epinephrine (present in anesthetic solutions). The interaction of these two substances can cause a rise in blood pressure as well as a change in heart rhythm. The explanation of this phenomenon (marijuana) can be answered pharmacologically. Smokers of marijuana trigger high liver enzyme activity, which is known to hasten the breakdown (metabolism) of the local anesthetics. This results in a situation of not being able to sustain profound anesthesia.  Comments to localanesthetics@yahoo.ca   Please visit  http://www.anestheticsnews.com Author: M.Sc. PharmD.

References
Haas DA. Localized complications from local anaesthesia. Journal of the
California Dental Association 1998 26:677-81.
Haas DA. Drugs in dentistry. In: Canadian Pharmacists Association. Compendium of pharmaceuticals and specialties.
Ottawa: CPA, 2002, L51-54.

Are stronger medication seeping into dentistry? The usage of compounds like Versed, Demerol and Fentanyl were not so common five years ago in dentistry. Why the change? Are local anesthetics failing? or are these new meds being offered more readily?

Bupivacaine 0.5%, a tertiary amide compound commonly used to induce nerve block anesthesia in dental procedures, continues to mystify pharmacologists with its dual properties of producing analgesia after soft tissue anesthesia has worn off. Although structurally it resembles other amides such as lidocaine; however, in the hydrophilic section, it contains four extra carbons. We suspect this is responsible for its unique mode of action. This is a desirable feature, since it reduces the need to prescribe narcotic type pain killers. Its concentration of 0.5% of bupivacaine  puts it in a class of low toxicity. Another useful tip on current issues. Comments are welcomed. Contact us at localanesthetics@yahoo.ca

The concern with Inderal (Propanolol) is not with amide local anesthetics but with epinephrine.  The interaction is as follows: 

As you know, there are two main classes of beta blockers - cardioselective and non-cardioselective.  The cardioselective beta blockers block only the beta-1 receptors (those responsible for making the heart beat faster and more forcefully) but leave the beta-2 receptors open.  The non-cardioselective beta blockers block both beta-1 and beta-2 receptors (those responsible for peripheral vasodilation and other effects).

Also, as you know, epinephrine is an adrenergic activist, stimulating alpha, beta-1 and beta-2 receptors.

If  someone is taking a cardioselective beta blocker and are given moderate to high doses of epinephrine in the local anesthetic, the epinephrine will want to stimulate both beta receptors but the beta-2 receptors are the only ones that are open.  This is good because the heart will not beat faster and more forcefully (the beta-1 receptors are blocked) but beta-2 mediated activation by the epi will cause vasodilation as usual.  This vasodilation will counteract alpha mediated vasoconstriction. (which is undesirable from a CVS perspective).  So the end result is no major effect on the patients cardiovascular system.

However if the patient is taking a non-cardioselective beta blocker (eg Inderal), both beta-1 and beta-2 receptors are blocked and so if they receive a moderate to high dose of epi, it can not stimulate either beta receptor.  All that happens is the alpha mediated vasoconstriction and this results in a rise in blood pressure (no counteracting beta-2 mediated vasodilation can occur) and to make matters worse, the patient will characteristically have a low pulse due to being on a beta blocker.  Low pulse and rising blood pressure is obviously a bad combination.  Direct comments or e-mail us at localanesthetics@yahoo.ca

Dentists who do venipuncture…is this an instrument you could use? 

Hemophilia affects infants and adults alike. Learning to perform IV injections is a necessary and critical skill. The new Venoscope 2 can help. The new device allows the average person, professional or not, to effectively locate and evaluate multiple IV sites for future IV access. It will give the family the luxury of mobility in travelling and recreation that they would normally be very reluctant to pursue for fear of being unable to administer factor in case of an emergency while away from home. Some factor providers have taken the position that by providing a Venoscope II to their clients, they enhance the quality of life for the whole family. 
The Venoscope  II was developed by a paramedic to aid in locating and evaluating peripheral veins for IV therapy and blood draws. The basic idea is “if you can see it, you can stick it”. The new Venoscope 2 transilluminator does this by directing a very bright light into the subcutaneous tissue so that it produces an orange glow when the external room lights are dimmed. When the light passes over a vein, the vein absorbs the light and the vein shows up as a dark line between the dual arms of the light. You can verify that it is in fact a suitable vein by depressing the arms and observing the vein collapse and refill when you release the pressure. We call this blanching the vein. If it does not blanch, it is not a suitable vein. It may even be a tendon which you definitely do not want to stick. At this point, you may mark the “target vein” and proceed with the stick or simply reverse the light with the vein located between the arms and proceed with the stick between the arms. You can ask someone to hold the light or attach the light to the patient’s arm with the Velstretch Strap. Check their sight at www.venoscope.com  Please feel welcomed to submit your your comments or e-mail at localanesthetics@yahoo.ca

After a routine IANB, a dirty trismus developed. What would be your choice of pharmacological intervention - Ibuprofen or gabapentine?

Please visit our CE courses at www.anestheticsnews.com       M.Sc. Phm.  Please e-mail us at localanesthetics@yahoo.ca