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Sample Chapter Textbook of Oral and Maxillofacial Surgery 2e by Balaji To Order Call Sms at 91-8527622422
 

Sample Chapter Textbook of Oral and Maxillofacial Surgery 2e by Balaji To Order Call Sms at 91-8527622422

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    Sample Chapter Textbook of Oral and Maxillofacial Surgery 2e by Balaji To Order Call Sms at 91-8527622422 Sample Chapter Textbook of Oral and Maxillofacial Surgery 2e by Balaji To Order Call Sms at 91-8527622422 Document Transcript

    • SECTIONIVChapters PagesAnaesthesia inOral Surgery9 Local Anaesthesia............................................................................................17110 General Anaesthesia........................................................................................197Chapter-09.indd 169Chapter-09.indd 169 4/13/2013 5:15:49 PM4/13/2013 5:15:49 PM
    • Chapter-09.indd 170Chapter-09.indd 170 4/13/2013 5:15:51 PM4/13/2013 5:15:51 PM
    • 9ChapterLocal AnaesthesiaTheories for mode of action oflocal anaesthesia 172Acetylcholine theory 172Calcium displacementtheory 172Surface charge theory 172Membrane expansiontheory 172Specific receptorhypothesis 172Mechanism of action 172Classification 173Systemic effects of localanaesthetic solution 174Properties of a localanaesthetic 174Composition of localanaesthetics 174Vasoconstrictors 175• Systemic effects ofvasoconstrictors 175Applied anatomy 176Basic injection techniques 177Nerve block 177Field block 177Local infiltration 177Auxiliary technique 177Intrapulpal injection 177Intraligamentarytechnique 177Intraosseous injection 178Intraseptal injection 178Topical local anaesthesia 178Block anaesthesia for themaxilla 178Intraoral techniques 178Posterior superior alveolar nerveblock 178Infraorbital nerve block 179Palatal anaesthesia 180Greater palatine nerveblock 180Nasopalatine nerve block 181Maxillary nerve block 182Extraoral techniques 183Infraorbital block 183Maxillary nerve block 184Block anaesthesia for themandible 185Intraoral techniques 185Inferior alveolar nerve block 185Direct technique (Halsteadapproach) 186Indirect technique (Fischer 1-2-3technique) 187Gow-Gates technique 188Vazirani-Akinosi’s closed-mouthmandibular block 189Mental nerve block 190Buccal nerve block 191Lingual nerve block 191Extraoral techniques 191Mental nerve block 191Mandibular nerve block 191Complications of localanaesthesia 193Complications occurring due toinjection technique 193Needle breakage 193Trismus 193Haematoma 194Facial nerve paralysis 194Diplopia 194Paraesthesia 195Oedema 195Postanaesthetic intraorallesions 195Infection 196Complications occurring due toanaesthetic solution 196Toxicity of the drug 196Allergy to the drug 196Burning sensation 196Chapter-09.indd 171Chapter-09.indd 171 4/13/2013 5:15:51 PM4/13/2013 5:15:51 PM
    • 172Section IV: Anaesthesia in Oral SurgeryLocal anaesthetics are the drugs that on coming incontact with the nerve fibre interrupt the propagation ofthe nerve impulse in a prolonged and reversible man-ner. Niemann isolated an alkaloid, cocaine, from cocaleaves which was later introduced as a local anaes-thetic in 1884 by Köller, an ophthalmologist, who alsonoticed the local vasoconstrictive and ischaemicaction of this drug. In 1905, Procaine was synthesisedby Einhorm as first local synthetic anaesthetics. Thiswas used until the discovery of lidocaine by Löfgrenin 1943.‘Local anaesthesia is defined as a transient andcompletely reversible loss of sensation in a circum-scribed area of the body caused by a depression ofexcitation in nerve endings or an inhibition of theconduction process in peripheral nerves.’METHODS TO INDUCE LOCAL ANAESTHESIA1. Mechanical trauma2. Low temperature3. Anoxia4. Chemical irritants5. Neurolytic agents such as alcohol and phenol6. Chemical agents such as local anaestheticsTHEORIES FOR MODE OF ACTION OF LOCALANAESTHESIA1. ACETYLCHOLINE THEORYAcetylcholine is involved in nerve conductiontogether with its role as a neurotransmitter at nervesynapses. But there is no evidence of involvement ofacetylcholine in neural transmission along the body ofthe neuron.2. CALCIUM DISPLACEMENT THEORYAccording to this theory, displacement of calciumfrom certain membrane sites that controls the perme-ability to sodium prevents depolarisation. Alteringthe concentration of calcium ions has no effect on localanaesthetic activity.3. SURFACE CHARGE THEORYLocal anaesthetics bind to the nerve membrane andchange the electrical potential at the membrane sur-face. LA molecules carrying net positive charge makethe electrical potential at the membrane surface morepositive, thereby increasing the threshold potential.Recent evidence shows that there is no alteration inthe resting potential by local anaesthetics and they actwithin the nerve membrane channels rather than atthe surface.4. MEMBRANE EXPANSION THEORYLocal anaesthetics diffuses to hydrophobic regionsand expands the membrane preventing the sodiumpermeability. Lipid soluble molecules alter the lipo-protein matrix of the nerve membrane and decreasethe diameter of sodium channels. There is no directevidence to support this theory.5. SPECIFIC RECEPTOR HYPOTHESISSpecific receptor hypothesis is the most favoured the-ory. Local anaesthetics act by attaching themselves tospecific receptors in the nerve membrane. The localanaesthetic receptor is located at or near the sodiumchannel in the nerve membrane either on its externalsurface or on the internal axoplasmic surface. Oncethe receptors access is gained, sodium ion permeabil-ity is decreased or eliminated and nerve conductioninterrupted.MECHANISM OF ACTIONLocal anaesthesia primarily acts by decreasing thepermeability of the nerve membrane to sodium ions.They have insignificant effect on potassium conduc-tance. Calcium ions present within the cell membranecontrol the conductance of the sodium ion across themembranes. The release of calcium ion from this cellmembrane results in an increased sodium permeabil-ity of the nerve membrane. This is the first step innerve membrane depolarisation. The local anaestheticmolecules act by competitive antagonism with cal-cium for the same site on the nerve membrane.Displacement of calcium ions from nerve receptor site↓Binding of local anaesthetic molecule to this receptorsite↓Blockade of the sodium channel↓Decrease in sodium conductance↓Depression of rate of electrical depolarisation↓Failure to achieve threshold potential level↓Lack of development of propagated action potential↓Conduction blockadeChapter-09.indd 172Chapter-09.indd 172 4/13/2013 5:15:52 PM4/13/2013 5:15:52 PM
    • 173CHAPTERLocal Anaesthesia 9CLASSIFICATIONPHARMACODYNAMICS ANDPHARMACOKINETICSLocal anaesthetic solutions can further be classifiedinto ester or amide type depending on their chemicallinkage (Tables 9.1–9.4). Ester-linked local anaesthet-ics are readily hydrolysed in aqueous solutionwhereas amide-linked local anaesthetics are relativelyresistant to hydrolysis.The ester type anaesthetics are metabolised by thehepatic pseudocholinesterases and plasmatic ester-ases, producing para-amino benzoic acid (PABA).which are excreted in urine. The ester type is 100%metabolised and the amide type is 90% metabolised,the remainder being unmetabolised anaesthetic.FACTORS AFFECTING ACTIVITY OFLOCAL ANAESTHESIA● Purely basic forms of local anaesthetics are not stableand dissolve poorly in water. However, weakly basicforms of local anaesthetic drug readily combine withacids to form local anaesthetic salt. This salt is stableand is soluble in water. Therefore, the local anaes-thetic solutions are available as salts, commonlyhydrochloric salt dissolved in distilled water andused for injections.● The effectiveness of the local anaesthesia is decreasedby the acidification of the tissues. Therefore, pooranaesthesia results when anaesthetic solution isinjected into an inflamed area.Table 9.1 Classification of local anaesthetics based onchemistryEsters Amides Quinoline● Benzoic acid estersButacaineCocaineBenzocaineHexylcainePiperocaineTetracainePrilocaineBupivacaineMepivacaineEtidocaineArticaineLidocaineCentbucridine● Para aminobenzoic acidesters:ProcainechloroprocainepropoxycaineTable 9.2 Classification of local anaesthetics according tobiologic site and mode of actionClass A Agent acting at receptor site—external surface ofnerve membraneClass B Agent acts at receptor site—internal surface ofnerve membraneClass C Agent acts by a receptor independent – BenzocaineClass D Combination of physiochemical receptors andreceptor independent mechanism (Most LAe.g. Lignocaine, mepivacaine)Table 9.3 Classification of local anaesthetics according toduration of actionDuration:PulpalDuration:Soft tissueLAUltrashort(10–15)30–45 Lignocaine 2% (plain)Mepivacaine 3% (plain)Prilocaine 4% (infiltration)Short (45–60) 120–180 ProcaineChloroprocaineIntermediate(60–90)180–270 LignocainePrilocaine (block)MepivacaineLong (>90) >270 BupivacaineEtidocaineTetracaineTable 9.4 Classification of LA based on mode ofadministrationI. Injectablea. Low potency, short durationi. Procaineii. Chloroprocaineb. Intermediate potency and durationi. Lidocaineii. Prilocainec. High potency, long durationi. Tetracaineii. Bupivacaineiii. Ropivacaineiv. DibucaineII. Surface anaesthetica. Solublei. Cocaineii. Lidocaineiii. Tetracaineb. Insolublei. Benzocaineii. Butylaminobenzoateiii. OxethazaineChapter-09.indd 173Chapter-09.indd 173 4/13/2013 5:15:52 PM4/13/2013 5:15:52 PM
    • 174Section IV: Anaesthesia in Oral Surgery● Local anaesthesia without epinephrine is more activethan the same agent with epinephrine because thepH of solutions with epinephrine is less (3.3) whencompared to the pH of solutions without epineph-rine (5.5).● Alkanisation of local anaesthesia increases its effec-tiveness and speeds up the action but since localanaesthesia is very unstable in its basic form, it can-not be used for clinical purposes.● Local anaesthetic agents are vasodilators. Thisresults in increased and fast absorption of the solu-tion into the bloodstream thereby increasing itstoxicity. The duration of local anaesthetic activity isalso decreased and bleeding at the site of adminis-tration is increased. The addition of epinephrinein the local anaesthetic agent overcomes all thesedrawbacks as it causes vasoconstriction of the localblood vessels.SYSTEMIC EFFECTS OF LOCAL ANAESTHETICSOLUTION1. CARDIOVASCULAR SYSTEMLocal anaesthetic decreases electrical excitability ofthe myocardium, conduction rate and force of con-traction. All these factors together result in myocar-dial depression (but not at a dose attained afterintraoral injection of one or two dental cartridges).At a dose of 1.5 to 5 μg/ml it has antiarrhythmic activ-ity. It can be used as a potent drug for ventriculartachycardia, ventricular premature contractions andin cardiac arrest from ventricular fibrillation.2. BLOOD VESSELSLocal anaesthetics cause vasodilatation of the bloodvessels except for cocaine which produces vasocon-striction. It primarily produces hypotension (at a levelapproaching overdose) due to depression of themyocardium and smooth muscle relaxation of thevessel wall. At lethal levels it causes cardiovascularcollapse.3. CENTRAL NERVOUS SYSTEMAt low level there is no significant effect. Lidocainecauses CNS depression at toxic levels.At 0.5–4 mg/ml—anticonvulsive actionDue to their depressant action on the CNS, localanaesthetics raise the seizure threshold by decreasingthe hyperexcitability of the cortical neurons fromwhere the convulsive episodes originate.At 4.5–7 mg/ml—preseizure signs andsymptomsPreseizure signs and symptoms include slurredspeech, shivering, tremor, warm flushed feeling of theskin, light headedness, dizziness, drowsiness, visualdisturbance, auditory disturbance, etc.At 7.5–10 mg/ml—convulsive actionAt this dose, lidocaine causes tonic-clonic seizure.Seizure continues as long as the drug is present in theblood. The duration of presence of local anaesthesiain blood is further increased by the increased bloodflow to the brain. Increased cerebral metabolism alsoleads to progressive metabolic acidosis which pro-longs the seizure activity.Further increase in the dose causes CNS depressionand respiratory arrest as a result of respiratorydepression.4. RESPIRATORY SYSTEMAt nonoverdose levels, it has a relaxant effect on bron-chial smooth muscles. Overdose leads to respiratoryarrest as a result of respiratory centre depression (CNSdepression).PROPERTIES OF A LOCAL ANAESTHETIC1. It should be nonirritant to the tissue to which it isapplied.2. It should not cause any permanent alteration ofnerve structure.3. Systemic toxicity should be low.4. It must be effective in parenteral as well as topicalapplication.5. Time of onset should be as short as possible.6. Duration of action should be adequate to com-plete the procedure as well as comfortablerecovery.7. It should be stable in solution and should readilyundergo biotransformation in the body.8. It should be sterile or should be capable of under-going sterilisation by heat without deterioration.COMPOSITION OF LOCAL ANAESTHETICSTable 9.5 depicts composition and function of localanaesthetics.In search of greater effectiveness for LA, vasocon-strictor agents are usually added to the anaestheticsolutions. This combination has constituted a realadvance in the field of stomatology, improving thedental operation.Chapter-09.indd 174Chapter-09.indd 174 4/13/2013 5:15:52 PM4/13/2013 5:15:52 PM
    • 175CHAPTERLocal Anaesthesia 92 ml of 2% lidocaine contains 36 mg of lidocainehydrochloride.1:80,000 of epinephrine contains 0.0125mg/ml and 1:1,00,000 concentration contains 0.01mg/ml of epinephrine.Safety levels of local anaestheticsThe toxic dose for lignocaine varies depending onwhether it is injected with a vasoconstrictor or not.Without a vasoconstrictor the toxic level is put at3–4.4 mg/kg. When a vasoconstrictor is added to thesolution the toxic level is raised to 7 mg/kg. The dif-ference is due to the more rapid uptake of lignocainewhen not used with a vasoconstrictor and is not accu-rate when the injection is given intravascularly.Absolute contraindications to localanaesthesia1. Myocardial infarction within 6 months2. Recent hepatitis A or hepatitis B3. Jaundice4. Local infections or sepsis5. Hypersensitivity to lidocaineRelative contraindications to localanaesthesia1. Chronic renal failure2. Hyperthyroidism3. Atypical plasma cholinesterase4. Pregnancy—during the first trimester5. Hypertension6. Malignant hyperthermia7. Congenital methaemoglobinaemiaVASOCONSTRICTORSVasoconstrictors used in local anaesthetics can be clar-ified based on chemical structure and mode of action(Tables 9.6, 9.7).Systemic effects of vasoconstrictors1. Cardiovascular systemIncreases cardiac output, stroke volume, systolic anddiastolic blood pressure, heart rate, myocardial oxy-gen consumption and force of myocardial contrac-tion. All these factors together result in decreasedcardiac efficiency.2. Blood vesselsThey have vasoconstrictive properties on small capil-laries which contain alpha receptors. However, inlarge blood vessels supplying skeletal muscles (whichcontain both alpha and beta receptors), beta 2 receptoractivity predominates in small doses and alpha recep-tor activity predominates in larger doses.3. Respiratory systemIt causes bronchodilatation of smooth muscles of thebronchioles (beta 2 effect).4. Central nervous systemIn therapeutic doses, epinephrine has no effect on theCNS. In excessive dose, it is a CNS stimulant.Table 9.7 Classification of vasoconstrictors based on modeof actionDirect-acting drugs Indirect-acting drugs Mixed-actingdrugsEpinephrine Tyramine MetaraminolNorepinephrine Amphetamine EphedrineLevonordefrin MethamphetamineIsoproterenol HydroxyamphetamineDopamineMethoxaminePhenylephrineTable 9.6 Classification of vasoconstrictors based onchemical structureCatecholamines NoncatecholaminesEpinephrine (natural) AmphetamineNorepinephrine (natural) MethamphetamineLevonordefrin (synthetic) EphedrineIsoproterenol (synthetic) MephentermineDopamine (natural) HydroxyamphetamineMetaraminolMethoxaminePhenylephrineTable 9.5 Composition and function of local anaestheticsComposition Function1. 2% LidocainehydrochlorideLocal anaesthetic agent2. 1: 80,000 to 1: 1,00,000EpinephrineVasoconstrictor prolongs theaction of the local anaesthetic3. Sodium metabisulphite Oxidising agent4. Methyl paraben Preservative5. Thymol Antifungal6. Distilled water SolventChapter-09.indd 175Chapter-09.indd 175 4/13/2013 5:15:52 PM4/13/2013 5:15:52 PM
    • 176Section IV: Anaesthesia in Oral Surgery5. MetabolismIt stimulates glycogenolysis in the liver and skeletalmuscles, thereby increasing blood sugar level. Itincreases oxygen consumption in the tissues.APPLIED ANATOMYTHE TRIGEMINAL NERVE (Fig. 9.1A–C)The trigeminal or fifth cranial nerve is the sensorynerve of face and consists largely of somatic afferentfibres but it also contains motor afferent fibres. It is thenerve of the first branchial arch and is the largest ofthe cranial nerves.The larger sensory and smaller motor root of thisnerve leaves the bone about half way up its ventrolat-eral surface. The cell bodies of the sensory root form thegasserian (trigeminal or semilunar) ganglion whichlies in an invagination of the dura mater near theapex of petrous temporal bone. The three divisions ofthe nerve leave the ganglion and exit from the skullvia the superior orbital fissure, foramen rotundumand foramen ovale. The innervation of the maxillaryteeth and adjacent soft tissues comes from the followingbranches of the second division, i.e. the maxillary nerve.a. The posterior superior alveolar (or dental) nerves, usu-ally two or three in number, leave the maxillarynerve in the pterygopalatine fossa to coursedownwards on the surface of the maxillary tuber-osity which they enter through small foramina tosupply the roots of all molar teeth except themesiobuccal root of first molar.b. The middle superior alveolar nerve arises from theinfraorbital nerve and supplies premolar teethand the mesiobuccal root of first molar.c. The anterior superior alveolar nerve arises furtheranterior in the infraorbital canal and supplies theanterior teeth.d. The greater palatine nerve travels via the greaterpalatine canal from the sphenopalatine ganglionto the hard palate. It supplies tissues on the palateposterior to the canine teeth.e. The long sphenopalatine nerve, after leaving thesphenopalatine ganglion passes medially throughthe sphenopalatine foramen, crosses the root ofnose to travel along the nasal septum and enterthe oral cavity via incisive canal. It supplies pala-tal tissues adjacent to the anterior teeth and anas-tomoses with greater palatine nerve in region ofthe canine tooth.These branches may be seen as describing twonerve loops: (i) the outer loop lies deep to the corticalbone of the maxilla and consists of the superior alveo-lar nerves and their parent nerve (the maxillary infra-orbital nerve) and (ii) the inner loop consists of thegreater palatine nerve only and the long sphenopala-tine nerve, which leave the sphenopalatine ganglionand anastomose near the maxillary canine tooth.The motor root runs with the third or mandibulardivision and supplies four masticatory muscles, twotensors (tympani and palati), anterior belly of thedigastric and mylohyoid.The innervation of the mandibular teeth and con-tiguous tissues arises from following branches of thethird division:a. The inferior alveolar nerve which enters the mandi-ble at the mandibular foramen and together withits terminal branches and incisive nerve, suppliesall the teeth.b. The mylohyoid nerve a branch of inferior alveolarnerve, runs downwards and forwards in mylohy-oid groove on medial surface of the ramus ofmandible to innervate the mylohyoid muscle.c. The lingual nerve which on its way to supply theanterior two-thirds of the tongue also supplies thelingual gingival tissues.d. The mental nerve which innervates the gingivaanterior to the mental foramen, as well as the skinand mucous membrane of the lower lip and chinapproximately to the midline.InfraorbitalnerveOphthalmicdivision (V1)Trigeminal nerve (V)Mandibulardivision (V3)Foramen ovaleMaxillary division (V2)Foramen rotundumAnterior trunk tomuscles ofmasticationTrigeminal ganglionSuperioralveolarnervesInferioralveolarnervesLingualnerveA B CFig. 9.1 A, B Course and distribution of trigeminal nerve. C Maxillary (V2) and mandibular (V3) division of trigeminal nervedermatome. ■ → V2; ■ → V3Chapter-09.indd 176Chapter-09.indd 176 4/13/2013 5:15:52 PM4/13/2013 5:15:52 PM
    • 177CHAPTERLocal Anaesthesia 9BASIC INJECTION TECHNIQUESDepending upon the site of injecting the local anaes-thetic solutions in relation to the nerve, there arethree major technique of LA as,● Nerve block● Field block● Local infiltrationThere are other auxiliary injection techniques as,1. Intrapulpal injection2. Intraligamentary technique3. Intraosseous injection4. Intraseptal injection5. Topical analgesiaNERVE BLOCKNerve block is the method by which regional anaes-thesia is secured by depositing the anaesthetic solu-tion within close proximity to a main nerve trunk.This will prevent the afferent impulses travelling cen-trally beyond this point.FIELD BLOCKField block is the method by which regional anaesthe-sia is secured by depositing the local anaesthetic solu-tion in proximity to larger terminal nerve branches.This will make the area to be anaesthetised walled offor circumscribed to prevent the central passage ofafferent impulses.LOCAL INFILTRATION (SUPRAPERIOSTEAL)(Fig. 9.2)In this technique, small terminal nerve endings in thearea of surgery are flooded with anaesthetic solution sothat the area becomes insensible to pain or prevent themfrom becoming stimulated and creating an impulse.AUXILIARY TECHNIQUEINTRAPULPAL INJECTION (Fig. 9.3)This technique is utilised in procedures which requiredirect instrumentation of the pulpal tissue. Intrapulpalinjection can adequately control pain arising frompulpal exposure.A 25-gauge needle is inserted into the pulp cham-ber; firmly wedging the needle into the chamber orcanal. Considerable amount of resistance might beencountered therefore, the solution is injected underpressure.INTRALIGAMENTARY TECHNIQUE(PERIODONTAL LIGAMENT INJECTION)(Fig. 9.4)Here the anaesthetic solution is deposited forcefullyunder pressure into the periodontal ligament (PDL) ofthe tooth which has to be anaesthetised. This techniqueis useful for anaesthetising only one tooth of maxillaryor mandibular arch. It may be necessary to repeat thePDL injection on all four sides of the tooth. This tech-nique is mostly used in restorative dentistry wheneverisolated areas of inadequate anaesthesia are present.Fig. 9.4 Intraligamentary injection.Fig. 9.3 Intrapulpal injection.Fig. 9.2 Local infiltration.Chapter-09.indd 177Chapter-09.indd 177 4/13/2013 5:15:54 PM4/13/2013 5:15:54 PM
    • 178Section IV: Anaesthesia in Oral SurgeryA 27-gauge short needle is placed between theperiodontal ligament and the tooth in such a way thatbevel of the needle faces the tooth to be anaesthetised.The needle may need to be bent for gaining access.A 0.2 ml of the local anaesthetic is deposited underpressure.INTRAOSSEOUS INJECTIONLocal anaesthetic solution is deposited into the can-cellous bone adjacent to the tooth to be anaesthetised.It is used when other methods have failed.The soft tissues are anaesthetised using a local infil-tration. A small incision is made in the apical region ofthe tooth to be anaesthetised and a hole is drilledthrough the dense cortical plate to reach the cancel-lous bone. A 25-gauge needle is inserted to this holeand approximately 1 ml of local anaesthetic solutionis deposited under pressure.INTRASEPTAL INJECTIONThe intraseptal injection is a variation of the intraosse-ous and PDL injections. This injection may be effec-tive where the condition of the periodontal tissues inthe gingival sulcus precludes the use of PDL injection.It is useful in achieving osseous soft tissue anaesthesiaand haemostasis for periodontal curettage and surgi-cal flap procedures.The soft tissue over the area is anaesthetisedthrough local infiltration and a 27-gauge short needleis inserted distal to the tooth in the porous intraseptalbone. 0.2 ml of the local anaesthetic is deposited underpressure. This technique is more effective in childrenand younger adults.TOPICAL LOCAL ANAESTHESIATopical local anaesthesia renders the free nerve end-ings in accessible structures incapable of stimulationby application of a suitable solution directly to thesurface of the area.BLOCK ANAESTHESIA FOR THE MAXILLAThe various injections are as follows:1. The posterior superior alveolar nerve block(tuberosity block)2. The anterior or middle superior alveolar nerve block(the infraorbital nerve block)3. The greater palatine nerve block4. The nasopalatine or long sphenopalatine nerveblock (the incisive canal block)5. The maxillary nerve block:a. Via the pterygomaxillary fissureb. Via the greater palatine canalc. By an external approachINTRAORAL TECHNIQUESPOSTERIOR SUPERIOR ALVEOLAR NERVEBLOCKOther names: Tuberosity block, zygomatic block.Areas anaesthetisedIn this technique, the area supplied by the posteriorsuperior alveolar nerve is anaesthetised. They are:pulpal anaesthesia of third, second and first maxillarymolars (with the exception of the mesiobuccal root ofthe maxillary first molar) buccal periodontium andbone overlying these teeth.LandmarksMucobuccal fold, maxillary tuberosity and zygomaticprocess of maxilla.Technique (Figs. 9.5–9.7)Position the patient so that his maxillary occlusalplane is at 45° angle to the floor. A 25-gauge shortPterygomaxillary fissureInferior orbital fissureMaxillary tuberosityLateral pterygoid plateFig. 9.5 Anatomical landmarks for PSA block shown in a skull.Chapter-09.indd 178Chapter-09.indd 178 4/13/2013 5:15:59 PM4/13/2013 5:15:59 PM
    • 179CHAPTERLocal Anaesthesia 9needle is used. The needle should be inserted at theheight of the mucobuccal fold in the region distal tothe maxillary second molar. The target area is the pos-terior superior alveolar nerve as it enters the posteriorsurface of the maxilla. This requires that the patient’smouth be opened only to a comfortable extent, asexcessive opening brings the coronoid process of themandible forwards and prevents the needle frombeing advanced from the lateral aspect. This nerve islocated posterosuperior and medial to the maxillarytuberosity.The index finger is placed in the mucobuccal foldof the bicuspid area and moved posteriorly until theprominence of the zygomatic buttress is reached. Thisis approximately in the region above the first molararea. Here the fingertip is rotated so that the fingernail is facing the attached gingiva. The finger is passedposteriorly over this buttress until it dips in a sulcusposterior to the buttress. The finger is kept such thatit is at an angle of 90° to the occlusal surface of themaxillary teeth and at an angle of 45° to the sagittalplane. The needle is positioned in the depth of the sul-cus close to the pterygomaxillary fissure, high in themucobuccal fold above the distobuccal root of the sec-ond molar, bisecting the finger nail.INFRAORBITAL NERVE BLOCKOther names: Anterior superior and middle superior alve-olar nerve block.Areas anaesthetisedIn this technique, the areas supplied by the anteriorsuperior alveolar nerve, middle superior alveolarnerve, infraorbital nerve along with its branches, thelateral nasal nerve, inferior palpebral nerve and supe-rior labial nerves are anaesthetised. Areas anaesthe-tised are maxillary incisors, canine, premolars andmesiobuccal root of maxillary first molar on theinjected side, buccal periodontium and bone of thesame teeth, lower eyelid along with lateral aspect ofnose and the upper lip.LandmarksSupraorbital notch, infraorbital notch, pupil of theeye, infraorbital foramen, bicuspid teeth and mentalforamen.Techniques (Figs. 9.8–9.12)There are basically three techniques for infraorbitalnerve block:i. Bicuspid approachii. Central incisor approachiii. Extraoral approachPatient is positioned in such a way that his/hermaxillary occlusal plane is at an angle of 45° to thefloor. The target is determined by palpating the supra-orbital and infraorbital notches. A vertical imaginaryline is drawn through these landmarks which will passthrough pupil of the eye, infraorbital foramen, bicus-pid teeth and mental foramen. After palpating theFig. 9.8 Surface anatomical landmarks. A vertical imaginaryline connecting pupil, infraorbital rim, notch, infraorbitalforamen and mental foramen.Fig. 9.6 Demonstration of PSA block in a skull.Fig. 9.7 Clinical demonstration of PSA block-needle placeddistal to second molar and directed 45° to the sagittal andocclusal plane with the buttress as a guide.Chapter-09.indd 179Chapter-09.indd 179 4/13/2013 5:16:00 PM4/13/2013 5:16:00 PM
    • 180Section IV: Anaesthesia in Oral Surgeryinfraorbital margin, the finger is moved downwardsfrom it where a concavity will be felt. This is the infra-orbital depression and the infraorbital foramen is in itsdeepest part. Maintaining the index finger on this fora-men externally, retract the lip using the thumb toexpose the mucobuccal fold or vice versa.Bicuspid approachIn the bicuspid approach, the needle is held parallel tothe bicuspid teeth. The puncture is made at a pointabout 5 mm from the mucobuccal fold which allowsthe needle to be advanced between the levator labiisuperioris above and the levator anguli oris below.Maximum penetration of the needle should be about2 cm; 1 ml of solution should be deposited and theoverlying tissues gently massaged to aid penetrationof the solution into the canal.Central incisor approachIn the central incisor approach, the needle is directedsuch that it bisects the crown of central incisor of thesame side to the mesioincisal angle to the distoincisalangle. The needle is inserted for about 5 mm from themucobuccal fold and 1 ml of anaesthetic solutiondeposited.Extraoral approachA 27 or 30 gauge needle is used to approach infraor-bital foramen percutaneously by injecting between alaof nose and upper part of nasolabial fold directingneedle laterally towards infraorbital foramen.PALATAL ANAESTHESIAPalatal injection proves to be a very traumatic experi-ence for many dental patients.GREATER PALATINE NERVE BLOCKOther names: Anterior palatine nerve block.Nerves anaesthetisedAnterior palatine nerve.Areas anaesthetisedPosterior portion of hard palate and its overlying softtissues, anteriorly up to the first premolar and medi-ally to midline.Fig. 9.9 Bicuspid approach demonstration in a skull.Fig. 9.10 Bicuspid approach. Needle oriented parallel to thebicuspids towards the infraorbital foramen with the indexfinger over the infraorbital rim acting as the guide.Fig. 9.11 Demonstration of central incisor approach in a skull.Fig. 9.12 Central incisor approach—needle bisects the centralincisor from mesial to distal penetrating the vestibularmucosa with the index finger over the infraorbital rim.Chapter-09.indd 180Chapter-09.indd 180 4/13/2013 5:16:03 PM4/13/2013 5:16:03 PM
    • 181CHAPTERLocal Anaesthesia 9Area of insertionSoft tissues slightly anterior to the greater palatineforamen.LandmarksGreater palatine foramen and junction of maxillaryalveolar process and palatine bone.Technique (Figs. 9.13–9.16)The greater palatine foramen is located about 4 mmanterior to the termination of the hard palate so that itis normally situated opposite the second molar abouthalf way between the gingival margin and midline. A27- or 25-gauge needle is used. The greater palatineforamen is approached from opposite side at a rightangle to the curvature of the palatal bone. The needleis inserted anterior to the foramen half way betweenthe palatal aspect of the gingival margin of the secondmolar and the midline of the palate. Approximately0.25 ml of solution is deposited here.NASOPALATINE NERVE BLOCKOther names: Incisive canal nerve block, sphenopalatinenerve block.Nerves anaesthetisedRight and left nasopalatine nerves.Areas anaesthetisedHard and soft tissues in the area between canine tocanine.Area of insertionTissue lateral to incisive papilla.Target areaIncisive foramen located beneath incisive papilla.LandmarkCentral incisors and incisive papilla.GreaterpalatineforamenFig. 9.13 Landmarks in the skull.GreaterpalatineforamenMidpalatinerapheFig. 9.14 Surface anatomical landmarks. Midpalatine raphe,palatal gingival margin of second molar and the half waybetween the two landmarks is the greater palatine foramen.Fig. 9.16 Clinical demonstration of greater palatine nerveblock—needle directed from opposite site just anterior to theforamen located 1 cm medial to the palatal gingival margin of2nd molar.Fig. 9.15 Demonstration of greater palatine nerve block in askull.Chapter-09.indd 181Chapter-09.indd 181 4/13/2013 5:16:06 PM4/13/2013 5:16:06 PM
    • 182Section IV: Anaesthesia in Oral SurgeryTechnique (Figs. 9.17–9.19)This procedure is extremely painful, therefore a pre-paratory anaesthesia is secured before insertion of theneedle into the incisive papilla.Preparatory anaesthesia0.25 ml of local anaesthetic solution is deposited byinserting the needle at a right angle to the labial plateinto the labial intraseptal tissues in between the twomaxillary central incisors.ProcedureThe position of the nasopalatine canal is markedby the papilla situated just behind the central incisors.The needle is withdrawn and reinserted slowly intothe groove surrounding the papilla. The bevel is bestplacedsothatitfacesdistallyandtheneedleisadvancedthrough the canal. Up to 0.25 ml of anaesthetic solu-tion is deposited.MAXILLARY NERVE BLOCKMaxillary nerve block is useful for profound anaes-thesia of the maxilla. Two approaches are usuallyemployed: (i) greater palatine canal approach—difficulty in locating and negotiating the canal and(ii) high tuberosity approach—higher incidence ofhaematoma.Other names: Second division nerve block, V2 nerveblock.Areas anaesthetised1. Pulpal anaesthesia of maxillary teeth on the sideof nerve block (central incisor to last molar)2. Buccal periodontium and bone overlying theseteeth3. Soft tissues and bone of hard palate and part ofsoft palate medial to the midline4. Skin of lower eyelid, side of nose, cheek andupper lipTechniquesMaxillary nerve block via the greaterpalatine canal (Figs. 9.20, 9.21)The puncture point for this injection is about 4–5 mmanterior to the greater palatine foramen, the needlehaving to pass through soft tissue before entering theforamen. The foramen opens into the greater palatinecanal, which is situated between the second and thirdmaxillary molars about 1 cm towards midline of thepalate from the palatal gingival margin.Occasionally, a slight depression may be notedoverlying the foramen. A 42 mm needle is passedupwards and backwards about 45–60° to the upperocclusal plane and slightly laterally (less than 10°) toalmost its full depth.Fig. 9.17 Surface anatomy in a skull—nasopalatine foramenin a severely resorbed maxilla.Fig. 9.18 Demonstration of nasopalatine nerve block inskull.Fig. 9.19 Clinical demonstration of nasopalatine nerveblock—needle insertion into the incisive papilla directed par-allel to the inclination of the central incisors.Chapter-09.indd 182Chapter-09.indd 182 4/13/2013 5:16:11 PM4/13/2013 5:16:11 PM
    • 183CHAPTERLocal Anaesthesia 9direction for approximately 30 mm. No resistanceshould be felt for advancing the needle; the presenceof any resistance indicates that the angle of the needletowards midline is too great. The tip of the needle isnow in the pterygopalatine fossa in proximity of max-illary nerve. About 2 ml of solution is deposited fol-lowing negative aspiration.EXTRAORAL TECHNIQUESINFRAORBITAL BLOCK (Figs. 9.22–9.25)Nerves anaesthetised● Infraorbital nerve and its branches: inferior palpe-bral, lateral nasal and superior labial● Anterior middle and superior alveolar nerveAreas anaesthetisedIncisors and bicuspids on the injected side, alveolarbone and overlying tissues, upper lip, side of the nose,lower eyelid.Fig. 9.22 Illustration of infraorbital nerve dermatome.Fig. 9.23 Surface anatomical landmarks for infraorbital nerveblock. Nasolabial fold, infraorbital rim, vertical imaginaryline through pupil connecting infraorbital foramen and mentalforamen, as a straight line.Fig. 9.21 Note the needle inserted into greater palatine fora-men ends in the pterygopalatine fossa anaesthetising the trunkof maxillary branch of trigeminal nerve (V2). Greater palatineforamen in the horizontal plate of palatine bone continues as acanal that opens into pterygopalatine fossa.Fig. 9.20 Maxillary nerve block through greater palatineapproach demonstration in skull.About 2 ml of solution is deposited and this usuallydiffuses adequately through the superior end of thecanal to reach the maxillary nerve. The patient’s headis tilted back with wide mouth opening to give goodaccess and possibility. Aspirate immediately as theneedle enters a tissue space, as inadvertent penetra-tion into the nasopharynx may be demonstrated byaspiration of air.Maxillary nerve block via thepterygomaxillary fissure/high tuberosityapproachA 25-gauge long needle is inserted high on the muc-cobuccal fold above the distal aspect of maxillary sec-ond molar. The bevel should be oriented towards thebone. To make this task easier, the patient is asked toopen his/her mouth partially and the mandible isretracted towards the side of injection. Advance theneedle slowly in an upward, inward and backwardChapter-09.indd 183Chapter-09.indd 183 4/13/2013 5:16:16 PM4/13/2013 5:16:16 PM
    • 184Section IV: Anaesthesia in Oral SurgeryLandmarksPupil of the eye, infraorbital notch, infraorbital ridge,infraorbital depression.TechniqueThe infraorbital foramen is located by using thelandmarks as mentioned for the intraoral approachand the foramen is marked. The overlying skin andsubcutaneous tissues are anaesthetised by local infil-tration. A 27-gauge needle is inserted through themarked area between ala of nose and upper part ofthe nasolabial fold and directed slightly upward andlaterally and entered into the foramen. It should notexceed a depth of 0.3 mm into the foramen. After neg-ative aspiration 1 ml of anaesthetic solution is depos-ited slowly.Fig. 9.26 Surface anatomical landmarks for extraoral maxil-lary nerve block—sigmoid notch, inferior border of zygo-matic arch.Fig. 9.27 Demonstration in skull—position I.Fig. 9.28 Clinical demonstration—position I: needle pene-trates perpendicular to the skin through the centre of the sig-moid notch and hits the lateral pterygoid plate.MAXILLARY NERVE BLOCK (Figs. 9.26–9.30)Nerves anaesthetisedMaxillary teeth, hard and soft palate, tonsils, maxil-lary alveolar bone and overlying tissues, nasal sep-tum and floor of the nose, anterior cheek, upper lip,side of the nose, lower eyelid, anterior temporal andzygomatic regions.Fig. 9.25 Clinical demonstration of infraorbital nerve block(extraoral)—needle directed towards infraorbital foramenjust lateral to the nasolabial fold directed superiorly andmediolaterally. This direction is in accordance with the infra-orbital foramen which opens inferomedially.Fig. 9.24 Surface anatomy of infraorbital foramen in a skullshowing the orientation of needle. Note the foramen opensinferiorly and medially.Chapter-09.indd 184Chapter-09.indd 184 4/13/2013 5:16:21 PM4/13/2013 5:16:21 PM
    • 185CHAPTERLocal Anaesthesia 9TechniqueThe midpoint of the zygomatic process and thedepression in its inferior surface are marked. A22-gauge needle of 4.5 cm is marked with a rubbermarker. The syringe is directed perpendicular to thesagittal plane until it contacts the lateral pterygoidplate. The insertion of the needle should not exceedthe rubber marker. Now the needle is withdrawn andredirected in a slightly forward direction and anaes-thetic solution is slowly deposited.BLOCK ANAESTHESIA FORTHE MANDIBLEThe nerves which supply the teeth and associated tis-sues of the mandible are the inferior alveolar nerve,with its mental and incisive branches, the lingualnerve and the long buccal nerve. The inferior alveolarFig. 9.29 Demonstration of position II in skull.Fig. 9.30 Clinical demonstration—position II. Needle with-drawn slightly and redirected anteriorly to the pterygomaxil-lary fissure.nerve and its two branches can be blocked at the man-dibular and mental foramina respectively. The lingualand long buccal nerves are blocked at very definitelocations.Following block injections will be described:1. Inferior alveolar nerve block2. Lingual nerve block3. Mental injection4. Long buccal nerve blockINTRAORAL TECHNIQUESINFERIOR ALVEOLAR NERVE BLOCKAlternative name: Mandibular blockNerves anaesthetised1. Inferior alveolar nerve2. Incisive nerve3. Mental nerve4. Lingual nerve5. Long buccal (occasionally)Areas anaesthetised1. Mandibular teeth to midline2. Body of mandible3. Inferior portion of ramus4. Buccal mucoperiosteum and mucous membraneanterior to mandibular first molar5. Lingual soft tissues and periosteum6. Anterior two-thirds of tongue and floor of oralcavity7. External and internal oblique ridgeLandmarks1. External oblique ridge2. Coronoid notch3. Buccal pad of fat4. Pterygomandibular raphe5. Pterygotemporal depression6. Pterygomandibular spaceTechniqueThere are basically two techniques for anaesthetisingthe inferior alveolar nerve.● Direct technique: Inferior alveolar nerve is anaesthe-tised first, hence it is known as direct technique(Halstead approach).● Indirect technique: Inferior alveolar nerve is anaes-thetised in the third position, hence it is known asindirect technique or ‘Fischer 1-2-3 technique’.Chapter-09.indd 185Chapter-09.indd 185 4/13/2013 5:16:28 PM4/13/2013 5:16:28 PM
    • 186Section IV: Anaesthesia in Oral SurgeryDirect technique (Halstead approach)(Figs. 9.31–9.36)Needle position● 1st positon: Inferior alveolar nerve is anaesthetisedfrom the opposite side.● 2nd position: Lingual nerve is anaesthetised from theopposite side.● 3rd position: Long buccal nerve is anaesthetisedseparate.Fig. 9.35 Clinical demonstration—position 2: anaesthetisinglingual nerve.Fig. 9.36 Clinical demonstration—position 3: anaesthetisinglong buccal nerve.Fig. 9.31 Anatomy of the inferior alveolar nerve and lingualnerve. Green colour indicates the inferior alveolar nerveentering the inferior alveolar canal. Yellow colour indicatesthe lingual nerve originating at the mandibular foramen andcoursing posteromedial to the last molar.Fig. 9.32 Demonstration of direct inferior alveolar nerveblock—position 1 in skull. Needle is directed from the contra-lateral premolars just behind the lingula anaesthetising theinferior alveolar nerve directly.Fig. 9.33 Clinical demonstration—position 1: anaesthetisinginferior alveolar nerve. Note the index finger placed alongthe deepest portion of anterior ascending ramus and needlebisecting it.Fig. 9.34 Demonstration of position 2 in skull: needleis withdrawn from Position 1 along the same directionwith simultaneous injection of LA to anaesthetise the lingualnerve.Chapter-09.indd 186Chapter-09.indd 186 4/13/2013 5:16:30 PM4/13/2013 5:16:30 PM
    • 187CHAPTERLocal Anaesthesia 9Technique (Fig. 9.38) Patient is seated in the dentalchair in supine or semi-supine position with mouthwide open such that his/her mandibular plane isparallel to the floor. Using index finger or thumb ofthe left hand palpate the external oblique ridge andmove the finger posteriorly till the coronoid notch(greatest depth of the anterior border of the ramus ofmandible) is contacted. The palpating finger is movedacross the retromolar triangle and onto the internaloblique; pterygomandibular raphe and pterygotem-poral depression can be seen clearly. Now place theindex finger or thumb behind the mandible extra-orally to assess the width of the mandible. A 25-gaugeneedle is inserted from the opposite side parallel tomandibular plane bisecting the thumb or index fingerup to half the distance between the palpating fingerintraorally and the finger behind the ramus of themandible extraorally until the needle contacts thebone. After negative aspiration, 1.8 ml of solution isdeposited slowly. The needle is now withdrawn abouthalf the inserted depth and the remaining local anaes-thetic solution injected to anaesthetise the lingualnerve. The long buccal nerve is anaesthetised using aseparate insertion between the external and internaloblique ridges.The tissue in the mucobuccal fold is entered withthe help of a 25-gauge needle at an angle of 45° to thebody of mandible just distal to the most posteriortooth.Indirect technique (Fischer 1-2-3 technique)(Figs. 9.37–9.42)Needle position● 1st position: Long buccal nerve is anaesthetised fromthe opposite side.● 2nd position: Lingual nerve is anaesthetised from thesame side.● 3rd position: Inferior alveolar nerve is anaesthetisedfrom the opposite side.Technique (Fig. 9.39) The position of the patientand identification of landmarks are similar to that forthe direct technique.1st position (long buccal nerve) Once the tip ofthe finger is on the internal oblique ridge the patient isasked to open his/her mouth wide and a 15/8 inchneedle is held in pen grasp and inserted from theopposite side bicuspid area into the mucous mem-brane bisecting the index finger nail. The clinicianshould not attempt to contact the bone. 6 mm of theneedle should have penetrated the tissues. 0.5 ml oflocal anaesthetic drug is deposited here to anaesthe-tise the long buccal nerve but usually this nerve doesnot get anaesthetised.Fig. 9.39 Demonstration in skull-Position 2. Without with-drawing the needle, the syringe is repositioned to the sameside and LA injected anaesthetising lingual nerve.Fig. 9.40 Clinical demonstration-Position 2: anaesthetisinglingual nerve from ipsilateral side.Fig. 9.37 Demonstration of indirect (Fischer 1, 2, 3) technique-Position 1: needle directed from contralateral premolarsbisecting the index finger for surface anaesthesia.Fig. 9.38 Clinical demonstration of Position 1.Chapter-09.indd 187Chapter-09.indd 187 4/13/2013 5:16:45 PM4/13/2013 5:16:45 PM
    • 188Section IV: Anaesthesia in Oral Surgery2nd position (lingual nerve) The syringe is with-drawn slightly and shifted on the same side so that itglides over the temporalis tendon on the internaloblique ridge. Here the needle is further advanced toa depth of 6–9 mm and 0.5 ml of local anaesthesiashould be deposited.3rd position (inferior alveolar nerve) The syringeis again returned to the opposite side and furtheradvanced to a distance of 12–15 mm until bony resis-tance is felt. After negative aspiration 1.8 ml of thesolution is deposited slowly to anaesthetise the infe-rior alveolar nerve.A tingling sensation in the lower lip and one half ofthe tongue indicates the effects of the anaesthesia.GOW-GATES TECHNIQUEDevised by Dr George Gow-Gates, a general practitio-ner of dentistry, in Australia in 1973. This techniquehas an advantage of higher success rate than inferioralveolar nerve block.Nerves anaesthetised1. Inferior alveolar nerve2. Mental nerve3. Incisive nerve4. Lingual nerve5. Mylohyoid nerve6. Auriculotemporal nerve7. Buccal nerveFig. 9.42 Clinical demonstration-Position 3: anaesthetisinginferior alveolar nerve from contralateral side bicuspids.Fig. 9.43 Demonstration of Gow-Gates technique in skull.Fig. 9.44 Clinical demonstration of Gow-Gates technique:mouth wide open and needle is directed parallel to the inter-tragic notch line drawn from the corner of the mouth to inter-tragic notch.Fig.9.45 The needle is angulated parallel to the divergence of earto face.Fig. 9.41 Demonstration in skull-Position 3: anaesthetisinginferior alveolar nerve.Chapter-09.indd 188Chapter-09.indd 188 4/13/2013 5:16:46 PM4/13/2013 5:16:46 PM
    • 189CHAPTERLocal Anaesthesia 9Areas anaesthetisedSame as inferior alveolar nerve block along with skinover zygoma, posterior portion of cheek and temporalregions.Target area: Lateral region of condyle neck, justbelow the insertion of lateral pterygoid muscle.LandmarksExtraoral: Lower border of tragus of ear, which cor-responds to the centre of external auditory meatusand corner of the patient’s mouth.Intraoral: Tip of the needle is placed just belowmesiopalatal cusp of maxillary second molar.Technique (Figs. 9.43–9.45)Patient is positioned in supine posture with neckextended and mouth wide open. This position facili-tates the injection by moving the condyle anteriorly.Now palpate the anterior border of the ramus of themandible and identify the tendon of temporalis mus-cle. Penetrate the needle gently into tissues just distalto maxillary second molar tooth at the height ofmesiopalatal cusp of second molar. The needle shouldbe just medial to the temporal tendon and directed inthe direction parallel to an imaginary line drawn fromthe corner of the mouth to the intertragic notch of theear and advanced until the fovea region of the condy-lar neck is contacted. With negative aspiration, deposit1.8 ml of solution over 60–90 seconds. The patient isasked to keep the mouth wide open for 20–30 secondsafter the injection to allow bathing of the nerve withthe solution.VAZIRANI-AKINOSI’S CLOSED-MOUTHMANDIBULAR BLOCKThis technique was originally proposed by Dr JosephAkinosi in 1977, which later on gained importancesince the landmarks are easily identified and the tech-nique is simple to master (Figs. 9.46–9.48).Nerves anaesthetised1. Inferior alveolar nerve2. Mental nerve3. Incisive nerve4. Lingual nerve5. Buccinator6. Mylohyoid nerveAreas anaesthetisedSame as inferior alveolar nerve block.Target area● Soft tissue on the medial border of ramus of man-dible in the region of inferior alveolar nerve, lingualand mylohyoid nerves.● Height of injection is below that of Gow-Gatestechnique.Fig. 9.46 Demonstration of Akinosi’s technique in skull.Fig. 9.47 Demonstration of Akinosi’s technique in skull. Notethe needle hitting the wire (indicating inferior alveolar nerve).Fig. 9.48 Clinical demonstration of Vazirani-Akinosi’s tech-nique: needle insertion medial to ramus at the height ofmaxillary molar mucogingival junction.Chapter-09.indd 189Chapter-09.indd 189 4/16/2013 12:27:23 PM4/16/2013 12:27:23 PM
    • 190Section IV: Anaesthesia in Oral SurgeryLandmarks1. Mucogingival junction of maxillary third or sec-ond molar2. Maxillary tuberosity3. Coronoid notch on ramus of mandibleTechniquePatient is positioned in the supine posture with theteeth occluded.Retract the lip to expose the maxillary and mandi-bular teeth. The syringe is directed parallel to theocclusal and sagittal planes at the level of mucog-ingival junction of maxillary molars. Penetrate theneedle just medial to the ramus of mandible25–30 mm into the tissues. Now the tip of needle liesin mid portion of pterygomandibular space, close tothe branches of mandibular nerve. With negativeaspiration 1.5–1.8 ml of anaesthetic solution isdeposited.MENTAL NERVE BLOCKNerves anaesthetisedMental nerve and terminal branch of inferior alveolarnerve.Areas anaesthetisedBuccal mucous membrane anterior to the mental fora-men, i.e. from first molar to midline, lower lip andskin of chin.Target areaMental nerve when it exits from the mental foramen,located between the apices of the first and secondpremolars.Technique (Figs. 9.49–9.52)The apices of the two premolars are estimated anda 1 inch, 25-gauge needle is used to puncture ata point just behind the mental foramen and some-what lateral to the depth of the labial sulcus (thecheek being retracted) so that about 1 cm of tissue ispenetrated. The needle is advanced to a positionbeneath the finger tip where gentle palpation shouldallow the foramen to be found. The needle travelsmainly downwards but also slightly anteriorly andmedially until the periosteum of the mandible isgently contacted. About 0.5–1 ml of solution is depos-ited and the fingertip is used to help massage it intothe canal.Fig. 9.49 Surface anatomy of mental foramen in a skull at theapex of premolars directed posterosuperiorly.Fig. 9.51 Demonstration of mental block in a skull—note thedirection of needle anteroinferiorly in accordance with theforamen anatomy.Fig. 9.52 Clinical demonstration of mental nerve block.Fig. 9.50 Illustration of mental nerve block dermatome.Chapter-09.indd 190Chapter-09.indd 190 4/13/2013 5:16:59 PM4/13/2013 5:16:59 PM
    • 191CHAPTERLocal Anaesthesia 9BUCCAL NERVE BLOCKAlternative names: Long buccal nerve block, buccinatornerve block.Target areaBuccal nerve as it passes over the anterior border oframus.LandmarksMandibular molars and mucobuccal fold.Technique (Figs. 9.35, 9.36)1. Buccal soft tissue is retracted with the index fingerof left hand.2. Syringe is directed towards injection site parallelto the occlusal plane on the side of injection.3. Penetrate needle distal and buccal to last molar.4. With negative aspiration, deposit 0.2–0.5 ml ofsolution.LINGUAL NERVE BLOCK (Fig. 9.53)The lingual nerve is usually blocked in the pterygo-mandibular space where it lies anteromedial to theinferior alveolar nerve, about 1 cm or slightly lessfrom the mucosal surface. It is possible to inject thisnerve either before or after the inferior alveolar nerveis anaesthetised.The lingual nerve can be blocked at a site posteroin-ferior to the 3rd molar by a submucosal injection oranaesthetised by infiltration at the site of surgery inthe lingual sulcus. Up to 0.5 ml of the solution is usedfor blocked side. An aspiration test is normally notnecessary.EXTRAORAL TECHNIQUESMENTAL NERVE BLOCKNerves anaesthetisedMental nerve, incisive nerve.Areas anaesthetisedLower lip, mandible and overlying structures anteriorto the mental foramen, mandibular teeth anterior tothe mental foramen.LandmarksBicuspid teeth, lower border of the mandible, supra-orbital notch, infraorbital notch, pupil of the eye.TechniquesThe supraorbital and infraorbital notches are locatedby palpation. An imaginary line is drawn throughsupraorbital notch, pupil of the eye, infraorbital notchwhich continues down to pass through mental foramen.A point which is mid way between the lower borderof the mandible and gingival margin is estimatedand marked on the imaginary line to locate the mentalforamen. A 22-gauge needle is directed slightlyanteroinferiorly towards the mental foramen thatopens in a posterosuperior direction. After negativeaspiration 1 ml of anaesthetic solution is depositedslowly into the foramen.MANDIBULAR NERVE BLOCK (Figs. 9.54–9.60)Nerves anaesthetisedMandibular nerve and its subdivision.Areas anaesthetisedTemporal region, auricle of the ear, external auditorymeatus, temporomandibular joint, salivary glands andlower portion of the face except the angle of the jaw.LandmarksSame as that for extraoral maxillary nerve block.TechniqueThe technique is same as that for maxillary nerveblock with the exception that the marker is placed at5 cm on the needle. When the needle contacts the pter-ygoid plate it is withdrawn and redirected slightlyupwards and posterior, so that it passes posterior tothe lateral pterygoid plate.Fig. 9.53 Demonstration of lingual nerve block in a skull.Note the nerve can be anaesthetised anywhere along itscourse.Chapter-09.indd 191Chapter-09.indd 191 4/13/2013 5:17:00 PM4/13/2013 5:17:00 PM
    • 192Section IV: Anaesthesia in Oral SurgeryFig. 9.58 Clinical demonstration-Position 1. Needle penetrates per-pendicular to the skin throughthe centre of the sigmoid notch.Fig. 9.59 Demonstration in skull—Position 2. Needlewithdrawn slightly and directed posterior to the lateralpterygoid plate and LA deposited close to the mandibu-lar nerve (V3).Fig. 9.55 Note the mandibular nerve (V3) exiting the foramenovale posterior to the lateral pterygoid plate.Fig. 9.57 Demonstration of same in skull.Fig. 9.60 Clinical demonstrationof Position 2 of mandibular nerveblock.Fig. 9.56 Demonstration in skull—Position 1. Needle directedperpendicular through the sigmoid notch hitting the lateralpterygoid plate.Fig. 9.54 Surface anatomical landmarks for extraoral mandib-ular nerve block—sigmoid notch, inferior zygomatic arch,lateral pterygoid plate. Note the mandibular nerve exiting theforamen ovale directed towards the mandibular foramen.Chapter-09.indd 192Chapter-09.indd 192 4/13/2013 5:17:02 PM4/13/2013 5:17:02 PM
    • 193CHAPTERLocal Anaesthesia 9COMPLICATIONS OF LOCALANAESTHESIA1. COMPLICATIONS OCCURRING DUE TOINJECTION TECHNIQUE● Needle breakage● Trismus● Haematoma● Facial nerve paralysis● Diplopia● Paraesthesia● Oedema● Postanaesthetic intraoral lesions● Infection2. COMPLICATIONS OCCURRING DUE TOANAESTHETIC SOLUTION● Toxicity of the drug● Allergy to the drug● Burning sensationCOMPLICATIONS OCCURRING DUE TOINJECTION TECHNIQUENEEDLE BREAKAGE (Fig. 9.61)Causes● Sudden and unexpected movement by the patientin the opposite direction of the needle insertionwhen the needle penetrates the soft palate● Reuse of the needle● Defective manufacturingPrevention● Use larger gauge needles● Use longer needles● Do not insert the needle till its hub● Do not redirect the needle in multiple directionsinside the tissues.Management● Remove the needle if it is visible, with the help of ahaemostat.● If not visible, take appropriate radiographs of theregion. Localise the needle and if in accessibleregion removal can be done surgically.● If the needle is lost into the tissue spaces, e.g. ptery-gomandibular space, infratemporal space, assurethe patient and review regularly. Unless compli-cated by pain or infection, fibrous capsule formsand the foreign body, requires no management.TRISMUSMuscle spasm resulting in defective mouth opening.Causes● Trauma to the muscles and blood vessels in theinfratemporal space.● Trauma to the muscle caused by repeated needleinsertion especially medial pterygoid in inferioralveolar nerve block.● Low grade infection● Excessive haemorrhage or haematoma whichproduces irritation of the tissues and muscledysfunction.● Solutions which contain alcohol or other cold steril-ising solutions irritate the tissues and producetrismus.Prevention● Use sharp, sterile, disposable needles as the traumaand infection caused by them is less● Do not use contaminated needlesFig. 9.61 Needle breakage. Broken needle in the pterygomandibular space (inferior alveolar nerve block).Chapter-09.indd 193Chapter-09.indd 193 4/13/2013 5:17:09 PM4/13/2013 5:17:09 PM
    • 194Section IV: Anaesthesia in Oral Surgery● The injection technique should cause as less traumaas possible● Clean the area of needle insertion with an antisepticsolution before injection● Avoid repeated insertion● Avoid using barbed needle that results when needlehits the bone● Change needle for every new insertions made.Management● Moist heat therapy wherein hot towels are appliedfor 20 minutes an hour● Analgesics for managing pain● Muscle relaxants● Physiotherapy involving dynamic jaw exercise.HAEMATOMAHaematoma is defined as effusion into the extravas-cular space. It is rare in the palatal region due to theclose adherence of the palatal mucoperiosteum to thebone.CauseDamage blood vessel by the needle during penetra-tion of soft tissues.Prevention● The surgeon should use an appropriate techniqueaccording to the anatomic structures.● The number of needle penetrations should be aslow as possible.● The surgeon should follow injection techniqueswith structures a lesser risk of haematoma.● The surgeon should use shorter needles for poste-rior superior alveolar nerve block.Management● Apply direct pressure over the bleeding site for afew minutes● Apply ice locally● Prescribe analgesics, antibiotics and musclerelaxants.FACIAL NERVE PARALYSIS (Figs. 9.62, 9.63)Usually occurs in inferior alveolar nerve block. Facialnerve is the motor supply to muscles of facial expres-sion. Loss of motor action of the muscles of facialexpression produced by local anaesthesia lasts forone to several hours. The patient suffers unilateralparalysis of the facial muscles.CauseInjection of local anaesthetic agents in the parotid cap-sule or within the substance of the parotid gland.PreventionEnsure that the needle tip contact the bone before thesolution is injected.Management● Reassure the patient and explain that it is transient● Remove contact lenses if the patient is wearing● Avoid further dental therapy and reassess forrecoveryDIPLOPIA (Fig. 9.64)Diplopia refers to double vision.CauseIt is caused by the paralysis of the lateral rectus dueto diffusion of anaesthetic solution directly from thepterygomaxillary fossa inferior orbital tissue to theorbit.Thiswill,inturn,affecttheciliaryganglionlocatedbetween the optic nerve and the lateral rectus muscle ofthe eye.Fig. 9.63 Transient facial palsy of left side during action.Fig. 9.62 Transient facial palsy of left side at rest.Chapter-09.indd 194Chapter-09.indd 194 4/13/2013 5:17:10 PM4/13/2013 5:17:10 PM
    • 195CHAPTERLocal Anaesthesia 9PreventionProper injection technique.ManagementReassure the patient by explaining the situation. Thediplopia lasts only for a few hours and will resolvewithout any residual effect.PARAESTHESIAIt refers to altered sensation in the area of skin ormucosa.Causes● Trauma to the nerve by inadvertent needlepenetration.● Injection of local anaesthetic solution with alcoholor cold sterilising solution near a nerve producesirritation and oedema of the tissues and subsequentpressure on the nerve● Haemorrhage around the neural sheath also causespressure on the nerve, leading to paraesthesia.PreventionProper injection technique.Management● Most cases resolve within 8 weeks● Reassurance to the patient● Review regularly to check for Tinel’s sign● If it persists for more than one year, it requires neu-rosurgical intervention.● If no recovery after 1 year, microneurosurgery maybe advocated.OEDEMAOedema (also known as dropsy or fluid retention) isswelling caused by the accumulation of abnormallylarge amounts of fluid in the spaces between thebody’s cells or in the circulatory system.Causes● Trauma● Allergy (angioedema is most common)● Haemorrhage● Infection● Injection of irritating solutionPrevention● Asepsis: Avoid injecting into abscess or infectionsite and reinjecting—area of the oral cavity● Use atraumatic techniques and gentle handling oftissues● Proper medical history of the patient.Management● Assess the type of oedema, cause and check forairway (no risk of obstruction) and vital signs● Traumatic oedema resulting from inflammationresolves in 1–3 days with antiinflammatory drugs.● Allergic oedema: Requires immediate assessment toavoid risk of anaphylaxis: treated with antihista-minics and steroidal antiinflammatory drugs.POSTANAESTHETIC INTRAORAL LESIONS● Recurrent aphthous ulcer or herpes simplex some-times develops after intraoral injection of localanaesthetics.● Herpes simplex develops on oral mucosa attachedto the bone, e.g. palate, attached gingiva● Recurrent aphthous stomatitis develops on oralmucosa not attached to the bone, e.g. buccal mucosa● Pain is the major symptom and may last for 7–10days.CauseTrauma to the oral tissues caused by the needle or anyother instrument reactivates the dormant disease.PreventionGentle handling of tissues.Management● Topical anaesthetics● Reassurance to the patient● Avoid steroidal antiinflammatory drugs.Fig. 9.64 Diplopia—due to paralysis of lateral rectus muscle(abducent nerve).Chapter-09.indd 195Chapter-09.indd 195 4/13/2013 5:17:11 PM4/13/2013 5:17:11 PM
    • 196Section IV: Anaesthesia in Oral SurgeryINFECTIONUse of unsterilised, contaminated needles can induceinfection.CauseCommonly involved pathogens include Pseudomonas,E. coli, Staphylococcus aureus, Mycobacterium.Prevention● Use of disposable syringes and needles● Use of appropriately sterilised needles● Avoid cross contamination between different siteswithin the oral cavity.ManagementTreat the infection with appropriate antibiotics.COMPLICATIONS OCCURRING DUE TOANAESTHETIC SOLUTIONTOXICITY OF THE DRUGThis refers to symptoms manifested as a result of overdosage or excessive administration of a drug. Theblood level of the drug necessary to produce a toxiceffect may differ for the same drug from one individ-ual to the other and in the same individual from dayto day. Clinically, the patient demonstrates talkative-ness, excitability, restlessness, lethargy, increasedblood pressure, tachypnoea, unconsciousness, etc.which are clinical presentation of extended systemiceffects.Causes● Accidental intravascular injection● High dosage● Rapid absorption into the bloodstreamPrevention● A thorough medical history of the patient prior toadministration of LA● Administration of minimal effective volume of drugsufficient to achieve the desired anaesthesia● Aspiration should be done before depositing thesolution● Slow administration of the anaesthetic solutionManagement● Treatment should be symptomatic● Discontinue any further administration of the LA● Adequate ventilation must be maintained● BLS is performed if required.ALLERGY TO THE DRUGAllergy is defined as a hypersensitive state acquiredthrough exposure to a particular allergen. Somepatients may be allergic to the LA solution. The clini-cal manifestations may vary from case to case andincludes angioedema, urticaria, dermatitis, fever,asthma, rhinitis and anaphylaxis.CauseSpecific antigen-antibody reaction in a patient whohas been previously sensitised to a particular drug orchemical derivative.Prevention● Intradermal test dose● No drugs should be administered if the patientgives a history of allergy.ManagementDepending on the degree of clinical presentation, it istreated by:● Antihistamine agents● Oxygen● Steroids● BLS administration if required● In case of anaphylaxis, management varies (refer toChapter 7 Medical Emergencies and their Management.)BURNING SENSATIONThis is not an uncommon complication during injec-tion of local anaesthetics.Causes● Decreased pH of the injected solution● Rapid injection● Contamination of local anaesthetic cartridges.Prevention● Slow administration of LA● Use of sterile cartridges.ManagementIn the majority of cases, the patient may not even beaware of the sensation and since it lasts for only a fewseconds, no management is required.Chapter-09.indd 196Chapter-09.indd 196 4/13/2013 5:17:13 PM4/13/2013 5:17:13 PM