Februari 02, 2017
local anesthetic injection techniqueslyle f. aseltine welcome to the university of michigan schoolof dentistry podcast series promoting oral health care worldwide. you have read about and seen additional materialon local anesthetic injection techniques. we're going to put it in motion for you bydemonstrating not only on the skull various injections but on a patient as well. you havepreviously seen or will see a tape on, uh, preparation of syringes both the carpule andthe luer lock type of syringe so we won't repeat that today. first of all, i'd liketo demonstrate proper patient position for you. we think about two different things whenwe think of patient position, the patient
who is going to receive an anesthetic injection.first of all, as you've read before, the most common complication in local anesthesia issyncope or fainting and we invite it when we have the patient sitting upright so asyou can see we have the patient tipped back to at least a degree of 50 to 55 degrees fromthe vertical and we'll avoid a lot of syncope and fainting. secondly, this allows you tosit or stand comfortably and see adequately into the oral cavity for the various injections. let us recall our landmarks for the inferioralveolar and lingual nerve block together needle bevel to the mandibular frenum. weutilize as you recall the anterior and posterior borders of the ascending ramus. we have thepatient open as widely as they can and then
we come in with our thumb of that hand andpalpate and find the greatest depth of the con cavity of the anterior border of the ascendingramus and you can see my finger on the posterior border of the ascending ramus in a like positionand we know the mandibular frenum lies on this plane approximately two-thirds the distancefrom the anterior border to the posterior border. as we make the approach with the syringe,we also at the same time have palpated the internal black lines so we know where it is.then we back our thumb off otherwise we'd be covering our injection site. we make theapproach with the syringe with the barrel on the opposite side, approximately over thebicuspids on the opposite side. the puncture is made and you will know if our thumb isin the right position it appears as if we're
bisecting our thumbnail. we carry on in acentimeter and a half or so and then increase the angulation of the syringe so that nowit's about over the first molar and we carry on in and then attempt to get the needle bevelagainst bone with a light touch approximately two-thirds of the distance from the anteriorto the posterior border. then we would aspirate naturally and inject the solution slowly whichwe will demonstrate on the patient. here we graphically see depicted the final positionof the needle and syringe at the mandibular frenum. the medial pterygoid muscle has beenpartially dissected away to uncover the mandibular frenum. you will note the relative heightof the mandibular frenum as is the position of the syringe over the bicuspid teeth onthe opposite side. let us now turn to the
patient and for purposes of showing this areabetter my assistant is going to retract the cheek on the opposite side so that you cansee a little better. andy, if you will just open real wide for me please. now to demonstratedrying the mucosa back in this area you will notice i do have a gauge strip here that i'veunrolled to its fullest length and i place my index finger over the end of it in thisfashion and we're just going to sneak along his mucosal plane and just lay it on the mucosain that area. don't wipe because many patients will gag if you stimulate them in that fashion.i just lay it there for a few moments and then with my left hand i remove the gauzeand at the same time my thumb is going in to get our landmarks. we have the mucosa dry.i do have my landmarks with my thumb and second
finger on the posterior border of the ramus.now we'll apply a little tincture of bedatine to our injection site. we have that accomplished. and now we'll goto our injection. i know where the internal black line is and our initial puncture willbe made just medium to it. syringe is over the bicuspids on the opposite side and wegive andy a little squeeze here with our, between our thumb and finger just to distracthim a bit, the puncture is made and i have penentrated approximately a centimeter, centimeterand a half. now i know i am by the obstruction of the internal black line. now i'm goingto increase the angulation of the syringe slightly so that now the barrel is approximatelyover the molar on the other side. now i'm
going to sneak on in and very gently try toget needle contact with bone at two-thirds of this distance across the ascending ramus.this i have done and now i going to aspirate carefully and we see that we're in a safeposition and now i'd like to show if we can my rate of injection of the anesthetic solution. you're doing fine andy. for our purposes today we'll just inject abouta cc of solution. however, normally you would want to inject approximately two ccs of injection.and then out quickly and allow your patient to close. the long buccal injection affords us anesthesiaof the buccal, alveolar soft tissues and vestibular
area which would be needed in addition tothe inferior alveolar and lingual nerve blocks if any instrumentation was to be carried outon these buccal alveolar soft tissues in the molar area of the mandible. now let us rememberthat in giving the long buccal injection in contrast to having the patient open as widelyas he possibly can for the inferior alveolar block, it is better to have them open slightlyhalf-way so that the cheek can be retracted. you have good access and vision and this alsocreates tension in the soft tissues of the vestibule so that the needle bevel can bepassed through easily with causing very little if any discomfort. let me just demonstratebriefly here now on the mandible approximately where we would inject to give the long buccalinjection. with the mandible closed slightly,
or approximately half-way, we would retractthe cheek and put a little tension on it so that the vestibular tissues are tense, theyare taunt. and our injection site would be approximately at the distal aspect of thesecond molar. now many times it is not necessary that needle bevel be against bone for thisinjection since these nerve fibers are very close below the surface of the mucosa. alrightlet's go to the patient. we ask our patient to open for us and onceagain we're going to retract on the opposite side throws a little more light in here soyou can see a little better. i am drying the mucosa again with our gauze pad just as beforeand then we retract his cheek as you can see here and this creates tension in these tissuesin the vestibule and our injection site and
we'll paint a little picture of betadine hereon our injection site.and our approach with the syringe well out in the vestibule and with these tight tissuesmany times we can make our little puncture here without any discomfort which we haveaccomplished now and our needle bevel is truly only three or four millimeters below the surfaceof the mucosa and now i'm going to aspirate to be sure that we're in a safe position whichwe are slight back pressure on the plunger and then we're going to inject slowly approximatelya cc of anesthetic which will usually be adequate to anesthetize the long buccal nerve. alright this we have accomplished and nowout quickly and let our patient close. as we've stated before the mandibular anteriorteeth can be successfully infiltrated through
labial infiltration which is not true of thebicuspids and the molars since we need the inferior alveolar and lingual blocks. withthe patient approximately half-closed again just as with the long buccal injection, uh,the lip can be grasped as we will show you when we come to the patient and protrudedanteriorly and outward thus again creating tension in these lower vestibular soft tissuesthrough which we can pass the needle bevel virtually without any discomfort. let us supposewe were going to infiltrate this lower cuspid and let's remember that the cuspid root isa little longer than the other anterior teeth than the incisors and our goal of course isto get the needle bevel against bone, through the vestibule, at a level of or slightly belowthe apex of this cuspid tooth in such a fashion
as this: needle bevel against bone, through the vestibule,and then our injection is made. alright let's go to the patient. alright let us demonstrate infiltration ofthe lower cuspid tooth. we just have him open partially until we get our retractor placedhere again to throw a little more light in here. now you'll notice that as i retractandy's lip here between index finger and thumb i retract it out and upwards slightly howthese tissues become quite tense here in the vestibule. you can see that quite nicely andif we can keep them tense again we can pass the needle bevel through them with literallyno discomfort. i'm going to dry the mucosa
again in the conventional way just layingmy gauze pad there for a few moments and then we'll apply a little betadine to our injectionsite. needle puncture out in the vestibule, at aboutthis angle and then carried right through to bone at a level of or below the apex ofthe cuspid tooth. remember again it's a little longer than the other incisors. alright thiswe have accomplished. i'm going to aspirate a little bit. you get no blood back in thesyringe we know we're in a safe position. and remember again that any time needle bevelis against bone you can lean on it a little bit this will elicit no discomfort whatsoever.and very slowly we'll inject approximately a cc and a half of solution
and then out quickly. now if we were goingto anesthetize one of the incisors, we're doing approximately the same thing. only ourneedle bevel wouldn't be against bone at quite as deep a level but we would come in in thesame fashion, through the vestibule, and carry it quickly to bone at a proper level. aspirate.and then we would inject approximately a cc to a cc and a half of solution. and then out quickly. all of these anteriorteeth can be infiltrated labially in this fashion. i should like to demonstrate lingual alveolarsoft tissue infiltration to you. let us suppose that we were going to remove this lower leftcuspid and we already accomplished labial
infiltration. we know that in removing thislower cuspid by force of application, etc., that we would be disturbing or manipulatingthese lingual alveolar soft tissues. now we can infiltrate in the floor of the mouth,right at the level of the cuspid where the tissues of the floor of the mouth sweep ontothe alveolar ridge and again it is not necessary to make deep penetration just two or threeto four millimeters below the surface of the mucosa and inject approximately a half a ccof solution which would accomplish anesthesia of these lingual alveolar soft tissues insuch a matter as this with the patient open widely, we can sneak in behind the anteriordentition here and right where the lingual soft tissues on the floor of the mouth reflecton to the alveolar ridge we make our puncture
and just carry several millimeters deep andagain deposit approximately half a cc of anesthetic solution and this will accomplish our purpose.let's try it on the patient. alright let's show it on the patient. andy if you'll openwide for me please. we'll dry our mucosa again in the usual fashion and then we'll applya little betadine right in the injection site right in the floor of the mouth where thosetissues reflect onto the alveolar ridge just lingual to the cuspid. and then we come inwith our syringe, at about this angle, make our penetration and just carry the needlebevel a few millimeters, two or three millimeters below the surface of the mucosa. and i amaspirating now. everything's fine. and very slowly we'll inject about a half a cc of solutionin this site and this will very adequately
anesthetize these lingual soft tissues adjacentto the cuspid. let us consider the posterior superior alveolarblock or injection sometimes called the zygomatic injection. you will recall that the posteriorsuperior alveolar nerves duck into the tuberosity of the maxilla, approximately two and a halfcentimeters directly above the maxillary third molar tooth. our greatest problem that weseem to have with the injection is getting into the pterygoid plexus of veins which liesout lateral to the tuberosity but there are things that we can do to help us with this.i'd like to show you briefly how we curve the needle with a sterile gauze to keep theneedle sterile so that we can keep close to bone as we approach the posterior superioralveolar foramina. you see i have a gauze
square here in my hand and we just lay thesyringe and needle on it and then i fold the gauze over it so that i am engaging it withfinger and thumb. and still at the same time keeping the needle sterile and i just giveit a little twist here these steel needles are a little passive so that you can get acurve in them. i don't know whether you can see that or not but you can see our needleis curved and this allows us to stay closer to bone as we approach the posterior superioralveolar foramina. alright let us show you on the skull now how we accomplish this. i'mgoing to tip the skull over here just a little bit so you can see a little better. alright with the mouth half-closed and againcheek retracted to get the tissues tense in
the vestibular area and at the time when we'redrying the mucosa we can very easily palpate the metotic strut or the zygomatic processbecause our initial puncture has to be made posterior to it and well out in the vestibuleso that as we curve and carry our needle to the posterior superior alveolar foramina areawe will stay close to bone. so we make the approach and my needle puncture will be wellout in the vestibule and approximately at a level of the second molar and now if youcan watch and see how i maneuver the syringe in an attempt to stay close to bone. i amcarrying it superiorly and laterally so that as we approach the foramina area i'm goingto be hugging the side of the tuberosity so that we stay close to bone and out of thepterygoid plexus of veins. graphically we
see the position of the syringe and needlebevel at the posterior superior alveolar foramina. in so doing this way we can stay out of theptyergoid plexus veins. with the posterior superior alveolar injection of course we anesthetizethe third molar, the second molar, and the first molar with the exception of the mesio-buccalroot, adjacent bone and buccal alveolar soft tissues. alright let's see if we can't showit nicely on the patient. again we're using a retractor which normally isn't necessaryjust so you can see a little bit better and first we'll dry our mucosa and you might closejust a tiny bit. at the same time i'm palpating the molar strut i know where it is about hereat the second molar and then we'll use a little betadine again as usual. our injection sitewell out in the vestibule this time. so as
we utilize our curved needle we can stay closeto bone as we approach the posterior superior alveolar foramina. we're at about a levelhere of the second molar and well out in the vestibule as you can see. very carefully makeyour initial puncture. now i'd like you to watch and see how i maneuver the syringe aswe approach the posterior superior alveolar foramina. i'm curving it upward, inward, andoutward and with a light touch we can actually feel the needle bevel penetrate the buccinatormuscle and we know that we've gone far enough superiorly. alright and we'll aspirate herea little bit. we're in good position. and now we'll veryslowly deposit about two ccs of solution and this should be adequate for the posteriorsuperior alveolar injection.
the posterior superior alveolar injectionis a distinct advantage -- we'll let andy close here for just a moment – a distinctadvantage where the molar strut lies over the first or second molar and you anticipateinstrumentation on that tooth and just to forge too much a border for a buccal infiltrationof that particular tooth to get through or for the solution to diffuse through and thereare occasions when the posterior superior alveolar block is needed to afford good anesthesiaof either the first and/or second molar depending on the site of the molar strut in relationshipto the particular tooth. we're going to demonstrate on the skull theanterior palatine injection which anesthetizes the anterior palatine nerve as it leaves theanterior palatine foramen and sweeps forward
to approximately the cuspid area on the sameside. this again will anesthetize all of these tissues, soft tissues from third molar tocuspid. we wish to avoid anesthetizing the middle and posterior palatine nerve sincethis gives a sensation of fullness to the lateral palate and lateral pharynx and itcreates a situation in which it seems difficult for the patient to swallow. you will recallthe anterior palatine foramen is on a plane anteriorialy and posteriorly with the thirdmolar and approximately half-way between mid-line and the third molar tooth. so we would makethe approach with the syringe with the mouth wide open so you can see nicely. and i'm justanterior to the anterior palatine foramen in the third molar region as you can see andwe deposit just a few drops of solution after
aspirating and you will find again that withthese palatial soft tissues due to their fibrous nature it is difficult to expel solution fromthe syringe into the tissues and you have to bring to bear quite a bit of pressure onthe plunger to do so. you will normally see the tissues blanch in this area due to thebasal constrictor in the solution and as you observe this you will know that you've gota few drops of solution at least out into the tissues here just anterior to the foramen.ideally from a quarter to a half cc of solution if you can injected at this site. now thiswill anesthetize as we've said before all of these palatial soft tissues from thirdmolar to cuspid which would be advantageous for instance if you're going to remove a quadrantof teeth and manipulate all these palatial
soft tissues from third molar to cuspid. nowon occasion, you may just be carrying out instrumentation on one tooth or removing onetooth it is necessary to block the entire anterior palatine nerve and we can infiltratejust palatially to the tooth in question and so-called get a partial anterior palatineblock. let's suppose we were going to remove this maxillary first bicuspid. it wouldn'tbe necessary to give the anterior palatine block but just simple infiltration about acentimeter from the gingival margin from the palatial side of that first bicuspid in sucha fashion as this. and again, with a little pressure on the plunger of the syringe andit does take a little pressure expel a few drops out into these tissues, needle bevelis against bone again and as you see the tissues
blanch you will know that you got some solutionout into the tissue. alright let us show you the anterior palatine injection on mr. fry,andy if you'll open real wide for us. that's great. now we'll dry the mucosa here first in theusual fashion. just resting it there for a few moments. and then we'll apply a littlebetadine in our injection site. now we'll make the approach with our syringe.now you can see i'm about at a level of the third molar and we make our puncture and carryour needle bevel clear to bone. then we aspirate again in the usual fashion. and then we expela few drops up to a quarter of a cc if you can and i can see those tissues blanchinga little bit i don't know whether you can
see it or not but we are getting some solutionout into the tissues and we know that we have accomplished our mission and then out quickly.and once again this will anesthetize all of the palatial soft tissues from third molarup to approximately the cuspid area where the [...] with the nasopalatine nerve. we'lllet you close for just a moment andy. now once again if we were just involved with onetooth or the instrumentation upon palatial tissue associated with one maxillary toothit wouldn't be necessary to block the entire anterior palatine nerve. let us suppose wewere going to remove the maxillary first bicuspid. i'll let you slip your retractor in thereagain please and you might turn away from me just a little bit that's fine. we dry themucosa just resting it there for a moment.
and then a little tincture of betadine rightin the area of the injection just palatial to the first bicuspid and then our punctureis made about a centimeter out from the free gingival margin on the palatial surface andapproximately that position and again needle bevel carried to bone and then we aspirateand then with quite a little pressure on the plunger we just literally need to inject afew drops of solution into the palatial soft tissues and again they're blanching a littlebit. it doesn't show too well here but they are, believe me. and that's all we need justa few drops. and then out quickly and that will allow instrumentation on these immediatelyadjacent palatial soft tissues of the first bicuspid.
alright, we'll demonstrate buccal infiltrationof the maxillary first molar and let's recall in so doing that we'll be anesthetizing boththe terminal branches of the posterior superior alveolar nerve and the middle superior alveolarnerve which anesthetizes the mesiobuccal root of the first molar and this anesthetizes thefirst molar and adjacent bone and overlaying alveolar soft tissues with the mouth halfclosed, again we retract the cheek to create tension in the vestibule and the needle punctureis made out in the vestibule and the needle bevel then carried to bone with at least the apex at a level of or preferableslightly above the apices or root of the first molar. injection slowly after aspiration ofapproximately two ccs of solution or those
of you who are using carpule syringes yourmaximum dosage for each injection is 1.8 ccs but that should be adequate and then out quickly.alright let's demonstrate it on the patient. andy, if you'll open about half way for meplease. and we might close just a little bit that's perfect andy. i'm drying the mucosahere now. and then we'll apply our tincture of betadine directly above the first molar.now you'll notice again with the cheek retracted how tense the vestibular tissues are. outin the vestibule i'm approaching the mucosa at about a 45 degree angle that you couldsee, puncture made, carried quickly to bone and then we aspirate and then we'll injecta good two ccs of solution to anesthetize the maxillary first molar.
the maxillary bicuspids are very simply infiltratedbuccally and remember again we are anesthetizing the terminal branches of the middle superioralveolar nerve. just as with the molar, with the mouth half closed, cheek retracted, andour needle bevel is directed toward the vestibule and quickly through the soft tissues and thenneedle bevel engaging bone at a level of or slightly above the apex of the bicuspid whetherit be the first or the second bicuspid. alright let's show that to you on the patient now.this is very similar to the molar infiltration, excuse me, except we're going to change thelevel of our needle bevel over the apex of the bicuspid instead of the molar. just closea little bit for me that's fine. we'll dry the mucosa again and let us show that we'regoing to anesthetize the maxillary first bicuspid.
a little tincture of betadine on the mucosa.now you can observe again the tight, tense vestibular tissues and our needle can veryeasily be passed through them. in fact on occasion you can bring the lip down and actuallypull the vestibular tissues over the needle bevel as you make the penetration and thenneedle bevel carried quickly to bone. we aspirate. and inject a cc and a half to a cc and three-quartersof solution and then out quickly. let us now depict anesthetizing the maxillarybicuspid and in so doing we'll recall the nerve supply to the bicuspid and incisor teethis the anterior superior alveolar nerves. remembering again the bicuspid root is a littlelonger than our other bicuspids and/or the incisors. labial infiltration, mouth half-closed,lip grasped and retracted laterally so the
vestibular tissues are again tense and taunt,needle directed superiorly through the vestibular tissues and quickly carried to bone, aspirationand injection of one and a half ccs of solution we'll anesthetize the maxillary bicuspid verynicely. now let's show it on the patient. if you would open about half way for me andy,please. and now you might close just a little. now with the retraction of andy's lip you'llnotice again these tense vestibular tissues. now we're going to get just a little higherbecause of the length of the bicuspid root. alright we've made your puncture and our needlebevel is against bone and we'll inject a cc and a half to two ccs of solution. and then out quickly.
to anesthetize the incisor teeth, again thesame technique labial infiltration with the mouth half closed, lip retracted anteriorly,needle bevel can be carried in through the vestibular tissues and quickly against boneat a level of or above the apices of the roots of either the central or the lateral incisortooth depending upon the tooth you are going to carry out the instrumentation upon. alright,let's again show it on the patient. same technique, tissue's dry, tincture betadine, through thevestibular tissues, against bone and aspiration, and again injection of a cc and a half ofsolution will very accurately anesthetize either the lateral or the central incisortooth. one last injection and again we return tothe palate the so-called nasopalatine injection
the terminal branches of the nasopalatinenerve as it's coming down from above from the nasal cavity and terminating from thenasopalatine canal at the nasopalatine foramen or sometimes called incisor foramen directlybehind the two central incisor teeth. and by anesthetizing the nasopalatine nerve wewill again afford anesthesia of all of these anterior palatine overlaying soft tissuesfrom approximately cuspid to cuspid areas which we would need if we were going to manipulatethese palatial anterior tissues in any fashion. as you look in the mouth you will see thereis a papilla that overlays the incisor foramen directly over it and we wish to avoid injectingdirectly into it since it is extremely sensitive to do so. so we find that it is adequate tomake the injection on either side of the foramen
and/or the papilla and we can very adequatelyanesthetize the terminal filaments of the nasopalatine nerve. so demonstrating thatfor us on either side, carried quickly into bone, aspirate, and then again it takes quitea little pressure on the plunger to get some solution out into these fibrous tissues butagain you will see them blanch as it occurs and know that you've accomplished in gettingsome solution out into those tissues. this is a mirror view of the anterior palatinearea and you can see the nasopalatine papilla right here very, very nicely. we'll dry ourmucosa and apply a little betadine again and we'll make our injection on just this sideof the papilla. it doesn't make matter whether you make it on the right or the left, oneor the other, don't inject directly into it.
alright we've got our needle bevel againstbone and i've aspirated and now i think as you can see as i press the plunger you cansee the papilla blanch and the adjacent surrounding soft tissue so we know that we are gettingsolution out in to the area of the incisor foramen to block the nasopalatine nerve. you have been listening to a presentationof the university of michigan school of dentistry which is dedicated to supporting open learningand open educational resources. this recording is licensed under the creative comments. itmay be reused and redistribute for nonprofit use. please attribute materials to the universityof michigan school of dentistry and redistribute under this same license. for more informationon how this and other university of michigan
school of dentistry recordings may be usedvisit www.dent.umich.edu/license.
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