Local anesthetic news

I was advised not to go into law because members of that profession were 3.6 times more likely to be depressed, than members of other professions and it’s not just because their jobs were more stressful. Job stress has little effect on happiness unless it is accompanied by a lack of control. For most professionals, such as dentistry, stress is rated at the high end of the scale. Apparently stress is evident only when results are difficult to reproduce. Dentists have to work with variables which are of an anatomical nature, hence the predictable or lack of it, puts them already at a disadvantage. This article may explain why dentists are stressed. They are caught between a rock and a hard place. On the one hand they are dealing with patients who hate the shrillness of the piercing sound of a drill or burr and on the other, the lack of scientific longitudinal studies dealing with biology vs technology. Ironically, replacing the drill, poses other biology problems which are yet to be evaluated over time. 

Lasers in some ways resemble the compound Vitamin E. In spite of the almost mystical image it has with the public, it remains one of these agents that some medical gurus have unanswered questions. The population at large says Vitamin E is good for everything but removing the grease from the kitchen sink. While the doctors are saying, “show me the clinical evidence”. When lasers were introduced for use in dental procedures it brought with it many attributes which dentists were screaming to have and were willing to pay the substantial price tag. Dentist felt if they could reduce or replace the use of drills, burs and maybe the shot, then dentistry would be perceived as less painful and improve traffic over and above acute procedures or emergency drop-ins.

This is a good time to revisit laser analgesia and anesthesia. Women love to tell the joke about men being lost, yet failing to stop and ask for directions. They would sooner drive around in circles. Dentists also have the perception that they are doing well at being pain free. For us lay people, according to dental text books on anesthesia, there has always been those files marked “difficult to freeze”. If your dentist is within that 15% range, then to him/her that is considered zero or perfection. However would you purchase a parachute or fire extinguisher with a label that says 15 % failure rate?  Let me make it perfectly clear, it is not a bad batch of anesthetic. If it were, then almost the entire continent would have the same problem.

Dentists are trained to diagnose and treat. If the diagnosis is accurate and the treatment completed then the job is done - fait accompli. Right? Let’s be honest, if you had company over for dinner and you knew the roast was overdone or something was just not quite right, would anyone be that discourteous to say, “by the way the roast was lousy”. Patients are mostly kind and will never tell you the truth. However unless you have not been in touch with the clinical side, most people hurt at the very thought of a visit to the dentist. For me, there is a disconnect here somewhere. Your own blogs admit it. This is not a gang up.  

The reality is that above and beyond that accepted 15% failure, we are aware of the times when there is a need to reinject or reach for that painful PDL. Yet other times when the patient is “numb” except on distal lingual line of a molar. How can someone be numb and still have residual sensation? The question is rhetorical, of course, but as dentists you are aware of accessory innervations and are supposed to know how to capture all nerves. If you translated that into English, a person could be half pregnant. I am serious. One is either frozen or not. If 15 % is being accepted, when do we see the benefits of higher post graduate education, more modern university facilities and yes, the tremendous work that researchers and pharmaceutical companies have been doing since 1947 when Astra introduced the first dental cartridge with Xylocaine? We are at the same 15 % failure rate as we were then. I am wiling to be proven wrong.

Yes, you have moved on to lasers, apex locators monitors and a myriad of new composites, but is the pain and discomfort still there? Yes, implants, Invisalign and TMJ’s are all up. Lab work has taken on new dimensions, but is the pain and discomfort still there? Forgive me for rhetorical questions. One dentist said to me about laser, I am all for this technology. I have 5 years clinically behind me with the laser and I have successfully removed large alloys, composites and done crown preps, however in a low whisper confessed that he wonders whether laser anesthesia/analgesia really worked. Here is a balanced one from the other side. The patient had a fracture (N0. 11) which was an abutment to a bridge. The nerve was exposed and vital she had a note from her medic to avoid amides. The procedure involved removing the nerve which would not have been possible before laser technology and the RCT was completed successfully.

It is essential for any laser used in dentistry as an alternative to a drill be concerned about biology. What about thermal damage which a laser can cause due to the heat that is generated by the ablation of these materials. The ablation efficiency of the Er:YAG laser (?=2.94) on dental materials and one must allow for timely removal of amalgam and composite dental restorations. While it would appear that I am not cutting much slack to dentists who are working through the difficult transition, I am really on your side and wish to present to the public a better image than what exists today. From a distance what I see is a ‘first on the block mentality’. This attitude is directed at fellow dentists down the hall as well as to patients in general. Unfortunately the soldiers are not all instep. There is a disconnect. When expectations are set and results of the climax turn into a whopping anti climax, you have one hell of a task to regain that spot.

Here you are all decked out with the bells whistles and flashing colored lights in each operatory and you are wearing the amber eye protectors and the atmosphere looks impeccable, yet when the local is delivered and the expectation is that the procedure will start now, there is the wait while the dentist is off to another patient or to the hygienist. When they eventually return, that is the anti climax. After 15 minutes and I am jumping each time a gloved finger or probe enters my mouth. This never happened in dental school. You gave the local and right away your colleague was frozen. Now it is reasonable for the dentist to have to move from room to room, but the reason given is bogus. When given correctly, anesthetics work within 30 seconds at the first time. Show me in any text book where 25 seconds is the recommended delivery time. They all say 1ml/min. There is the problem.   

The term to “marinate” is not usually used by dentists, but we in pharmacy are familiar with the terminology. It basically means that the dentist may start injecting at multiple locations, with a hope that luck may be on his/her side and the patient will be frozen. My advice, speaking as a pharmacist and having the knowledge of how most drugs work, is that these multiple shots are warnings of trouble ahead. The flashing yellow is on and it may be telling you that the first injection did not do the job. The second and third (all the same drug, just by a different manufacturer’s name) will magically perform a trick from the turtle to the rabbit. (Sorry folk! this is an inside joke) your dentist may want to explain.

The dentist could sit with for an hour and explain in a similar way the salesman gave a demo at the trade show. However, you the patient are not interested with precision or smear layers. All you want is to feel nothing. To put it bluntly, you want to be fully frozen throughout the procedure. As a comparison, think of a knee implant under conscious sedation. The patient hears the saw and is aware, but there is no pain.

The biology of laser usage is still not known. It is an attempt to spare the patient the thought of a burr, drill and vibration. However, when we are dealing with living body parts, biology of structure, function, growth, origin, evolution and distribution must be factored in with longitudinal specific clinical studies. There are some prominent opinion leaders in perio who have refused to continue to lecture on closed flap crown lengthening. An area of concern is laser plume virus survival and thermal damage. Dental laser technology is here to stay because there are times when the alternative would have been general anesthesia because of severe anaphylactic shock if a local were used. However I fore see a revisit to closed technique because of the risk of bone necrosis.

A recent published article in the Journal of Periodontology, conducted at the University of Missouri, Kansas. Mullins, S.L., et al. - The purpose of this pilot study was to evaluate, by scanning electron microscopy (SEM), the surface effects of 3-CO2 laser treatment on the root surfaces and soft tissues and to investigate the effects of 3-CO2 laser on periodontal pathogenic bacteria compared to negative controls…A one-time use of the 3-CO2 laser in periodontal pockets did not sterilize or substantially reduce subgingival bacterial populations compared to negative controls.

In this age of better skills, more accurate and definitive diagnostic equipment and excellent patient compliance, there is obvious something missing when we hear the comment . . . “hang on there, we are just about finished.” Life styles have changed. That is one of my lecture topics. I hope you are not too deep in the forest to see the trees.

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

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