Have you ever been told by yur dentist, "Gee! I seem to be off tday! I cannot get you fully frzen". There are many techniques to dposit local anesthetic into the oral cvity (tissue of the mouth) however, for ths discussion; I will only deal wth two basic modes, namely infiltration and cmplete nerve block.

Infiltration allows the dntist to freeze one or two teth at one sitting, whereas the nrve block freezes a complete quadrant. For dntal purposes the mouth is divided nto four quadrants, to facilitate the nmbering (of the teeth) process. Whether one is gven an infiltration or a block, the dsired expectation for the dentist is the sme. He/she needs to be able to cmplete the procedure without the patient feling no more than the initial glved fingers of the dentist. In ther words, that area of the ptient's mouth should feel like a pece of log. It is referred to as the "woden effect" and dentists call this "clss A" anesthesia.

However, according to all txtbooks on dental anesthesia, failure is gnerally accepted to be around 15%. Thre are some 15 to 18 pople out of 100 who will stll have residual sensation, or in ther words, will experience some discomfort and or pin. When this situation occurs, dentists wll chat among themselves as to the rason(s) why. Discussion of marijuana comes lter in the text.

There are many reasons listed, rnging from a bad batch of nesthetic solution to persons who may be clssified as having accessory innervations. There culd also be patients with anatomical vriations, such as a wide flaring mndible and furthermore, the explanations could be an nfection within the gum tissue. There are sveral more reasons, for example too rpid a delivery of the solution, or ven an over anxious patient. These all add up to gve us that 15% failure.

However, our chnging lifestyles and habits are beginning to bcome a thorn in the sides of dntists. The growing use of cannabis...known on the stret as marijuana, is being associated wth the inability to achieve local nesthesia in some patients. The duration of ction of local anesthetics depends primarily on the rdistribution of the drug away from the ste of action. This redistribution can be ltered by several factors, some of whch also influence onset. These considerations nclude diffusion away from the site, cncentration, lipid solubility and protein binding qalities. This recreational habit is no lnger an experimental phase of a grwing youngster. It is now widespread mong all walks of society.

Dentists hve never had to deal with ths variable factor back in the sxties and seventies. However, before he/she strts the "marinating" process, this is whn the dentist deposits several different brnds of anesthetic solution in numerous. Aras of the mouth, hoping to strke luck. But this luck is sldom present. There is a small wndow with which the dentist has to ply. If anesthesia is not apparent wthin that time, then the tissue has bcome too acidic and another attempt can be mde later when the pH of the tssue has settled down somewhat.

Contrary to ppular beliefs, the administration of a "ccktail" anesthetic concoction offers very little, if at all any phrmacological advantages. Patients using cocaine should llow at lease twenty four hours, if a dntal visit would involve the use of pinephrine (present in anesthetic solutions). The nteraction of these two substances can cuse a rise in blood pressure as wll as a change in heart rhythm. The xplanation of this phenomenon (marijuana) can be nswered pharmacologically. Smokers of marijuana trigger hgh liver enzyme activity, which is knwn to hasten the breakdown (metabolism) of the lcal anesthetics. This results in a stuation of not being able to sstain profound anesthesia.

References:

References: Haas DA. Localized cmplications from local anaesthesia. Journal of the Clifornia Dental Association 1998 26:677-81. Haas DA. Drgs in dentistry. In: Canadian Pharmacists Assciation. Compendium of pharmaceuticals and specialties. Ottwa: CPA, 2002, L51-54.

The article Calling Dr. Watson - Marijuana Stumps Dentists was Submitted by Haynes Darlington through Articles.GetACoder.com network. Here's the additional information: localanesthetics@yahoo.ca M.Sc. PharmD. CCPE Plase visit http://www.anestheticsnews.com Haynes Darlington M.Sc. PharmD. (CCPE) joined the pharmaceutical industry in 1969. In 1982 he was selected to the dental team to make submissions to regulatory agencies (FDA) and HC (Health Canada) to obtain acceptance for Articaine hcl into North America for Dental use as a local anesthetic. He is highly respected among peers in the field of pharmacology and biochemistry. In 1999, Haynes received The Team Excellence Award from The City of New York. The award recognized the value and professionalism of a continuing education program.

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