Important Arterial Supply of the Mandible, Control of an Arterial Hemorrhage, and Report of a Hemorrhagic Incident

IMPORTANT ARTERIAL SUPPLY OF THEMANDIBLE, CONTROL OF AN ARTERIALHEMORRHAGE, AND REPORT OF AHEMORRHAGIC INCIDENTCLINICALDennis Flanagan, DDSKEY WORDSDental implantsLingual arteryFacial arteryInferior alveolar arteryMylohyoid arterySubmental arterySublingual arteryHemorrhageDennis Flanagan, DDS, is in the privatepractice of general dentistry. Addresscorrespondence to Dr Flanagan at 1671 WestMain Street, Willimantic, CT 06226 ([email protected]).Penetration of the mandibular cortex during dental implant surgery may damage3 important arteries and could lead to life-threatening circumstances. To lessen thelikelihood of lateral angulations and cortical perforations, dental implants of lessthan 14 mm may be considered for the mandible. The courses of the inferioralveolar, facial, and lingual arteries and their branches are reviewed. Managementof hemorrhage from a branch of the lingual or facial arteries may require anextraoral approach for ligation, because the mylohyoid, sublingual, and submentalarteries can anastomose and be anatomically variable as well. A violation of 1 ofthese may be difficult to manage and lead to a compromise of the airway. Acortical perforation may be avoided by studying the anatomy of the ridge beingtreated. This article discusses what procedures to perform to obtund bleeding from1 of these arteries and the technique of performing an emergency tracheotomy.INTRODUCTIONhree arteries that providethe major blood supply tothe mandible are importantfor dental implantology.These are the lingual, facial,and inferior alveolararteries. The first 2 arise directly fromthe external carotid, a major artery. All3 supply structures in and around themandible. A perforation of the facial orlingual cortex of the mandible and aseverance of a branch of 1 of these arteriesduring an osteotomy may resultin a life-threatening situation. Uncontrolledbleeding from the lingual artery,if left unchecked, may cause anexpanding ecchymosis that could compromisethe airway and/or blood volumeand may result in fatality.REVIEW OF THE ANATOMYLingual arteryThe lingual artery arises from the externalcarotid artery between the superiorthyroid and facial arteries (Figures1, 2, and 3). In 20% of cases, thefacial and lingual arteries arise from acommon trunk; rarely will the lingualand superior thyroid arteries arisefrom a common stem. The first portionis crossed by the hypoglossal nerveand is contained within the carotid triangle.This anatomic triangle is formedby the sternocleidomastoid muscleJournal of Oral Implantology 165ARTERIAL SUPPLY OF THE MANDIBLEFIGURE 1. Key: (1) Facial artery; (2) lingual artery; (3) external carotid artery; (4) superiorthyroid artery; (5) hypoglossal nerve; (6) hypoglossus muscle; (7) hyoid bone; (8) sublingualartery; (9) genioglossus muscle; (10) geniohyoid muscle; (11) sublingual salivary gland; (12)deep lingual artery; (13) styloglossus muscle. LifeART image copyright (2003), LippincottWilliams Wilkins. All rights reserved.FIGURE 2. Key: (1) Facial artery; (2) external carotid artery; (3) superior thyroid artery; (4)lingual artery; (5) hypoglossus muscle; (6) submental artery; (7) sublingual salivary gland;(8) sublingual artery; (9) deep lingual artery. LifeART image copyright (2003), LippincottWilliams Wilkins. All rights reserved.posteriorly, superior belly of the omohyoidmuscle inferiorly, and superiorlyby the stylohyoid muscle and posteriorbelly of the digastric muscle. This firstportion of the artery also rests on themedial constrictor pharyngeal muscleand is covered by the cervical fasciaand platysma muscle. The artery thencourses medially and cranial to thegreater horn of the hyoid bone. It thenturns inferiorly and facially to form aloop and crosses the hypoglossalnerve. This loop of the artery also lieson the medial pharyngeal constrictor,covered first by the tendon of the di-166 Vol. XXIX/No. Four/2003gastric and the stylohyoid and then bythe hyoglossus muscle. Then it passesdeep to the digastric and stylohyoidmuscles and goes medially to coursebetween the hyoglossus and genioglossusmuscles. The terminal portion thenrises into the tongue and runs alongthe underside of the tongue to the tip.The branches of the lingual arteryare the suprahyoid, dorsal lingual, sublingual,and the deep lingual (alsoknown as the profunda linguae or ranineartery).The suprahyoid branch runs alongthe superior border of the hyoid boneand supplies the muscles attached tothis bone (geniohyoid, hyoglossus, mylohyoid,sternohyoid, omohyoid, thyrohyoid,digastric, stylohyoid, chondroglossus,and constrictor pharyngesmuscles). The artery then anastomoseswith the contralateral artery of thesame name.The dorsal lingual arteries have 2or 3 branches that arise under the hyoglossusmuscle and ascend to the posteriorportion of the tongue to supplythe dorsum of the tongue, mucousmembrane of the area, glossopalatinearch, tonsil, soft palate, and epiglottis.These branches then anastomose withthe branches of the opposite side.The sublingual branch arises fromthe lingual artery at the point the anteriormargin of the hyoglossus muscleis crossed. The branch then courses betweenthe genioglossus and mylohyoidmuscles and continues on to supplythe sublingual salivary gland, the mylohyoidand surrounding muscles, andthe mucous membranes and gingivaeof the mandible. One more distalbranch runs medially in the anteriorlingual mandibular gingivae to anastomosewith the contralateral artery.Another branch goes through the mylohyoidmuscle and connects with thesubmental branch of the facial artery.The deep lingual artery is the tortuousterminal portion of the lingualartery. It runs along the undersurfaceof the tongue between the inferior longitudinalmuscle and the mucousmembrane on the lateral side of the genioglossusmuscle. At this point it isaccompanied by the lingual nerve. Thedistal end anastomoses with the contralateralterminus at the tip of thetongue.Facial arteryThe facial artery originates from theexternal carotid, superior to the lingualartery, which is in the carotid triangleand medial to the ramus (Figure 2). Itpasses deep to the digastric and stylohyoidmuscles and arches anteriorlyto enter a groove on the submandibularsalivary gland. From here it is ac-FIGURE 3. Key: (1) External carotid artery; (2) lingual artery; (3) dorsal lingual arteries on thegenioglossus muscle; (4) hyoid bone; (5) hypoglossal nerve (cut and retracted); (6) geniohyoidmuscle; (7) sublingual artery; (8) lingual nerve; (9) hypoglossus muscle (cut); (10) facial artery.LifeART image copyright (2003), Lippincott Williams Wilkins. All rights reserved.companied by the facial vein. It thenbecomes superficial and winds aroundthe inferior border of the mandible atthe anterior border of the massetermuscle to enter the face (Figure 4). Itcrosses the cheek, follows along theside of the nose, and ends at the medialcommissure of the eye, where it isknown as the angular artery. The facialartery is extremely tortuous, whichpermits it to accommodate the movementsof the face and mandible withoutcompromising its integrity or itsvascular function.There are 2 main branches of thefacial artery: the facial and cervical.The 5 branches of the facial portionsupply the facial areas about the eye,nose, and lips. There are 4 branches ofthe cervical portion. The ascendingpalatine and tonsillar branches supplythe structures of the pharynx, soft palate,and auditory tube. The glandularbranch consists of 3 or 4 vessels thatsupply the submandibular gland, lymphatics,and the overlying skin. Thesubmental branch is the largest of thecervical branches and arises from thefacial artery (Figures 2 and 4). At thissite it leaves the groove of the posteriorsubmandibular gland and runs anteriorlyon the surface of the mylohyoidmuscle inferior to the body of the mandibleand deep to the digastric muscle.The submental branch anastomoseswith the sublingual branch of the lingualartery and with the mylohyoidbranch of the inferior alveolar artery.Dennis FlanaganAt the symphysis of the mandible, thesubmental branch turns superiorly beneaththe border of the mandible anddivides into its superficial and deepbranches. The superficial branch approachesthe surface and runs on theinferior labial levator muscle and anastomoseswith the inferior labial artery.The deep portion runs deep to the inferiorlabial levator, supplies the lip,and anastomoses with the inferior labialand mental arteries.Inferior alveolar arteryThe inferior alveolar artery arises fromthe maxillary artery, which is the largerof the 2 terminal branches of the externalcarotid (Figure 5). As the inferioralveolar artery descends, it gives offthe mylohyoid artery before enteringthe mandibular foramen and the mandibularcanal. At the first molar, it dividesinto the mental and incisalbranches. The incisal branch continuesin the mandibular canal anterior to themental foramen and presents branchesto the incisor teeth and finally to anastomosewith its contralateral mate. Themental branch emerges from the mentalforamen to supply the chin andlower lip and anastomose with thesubmental and inferior labial arteries,which are branches of the facial artery.The mylohyoid artery leaves the inferioralveolar artery and runs on themedial surface of the mandible in themylohyoid groove and continues tosupply the mylohyoid muscle. A smalllingual branch can arise from the inferioralveolar artery near its originand descend with the lingual nerve tosupply the mucosa of the floor of themouth.1REPORT OF A HEMORRHAGICINCIDENTA 57-year-old woman, with a noncontributorymedical history, fractured hermandibular right first molar. A radiographrevealed that the fracture wassubosseous and the tooth was deemedunrestorable. The right mandible wasanesthetized by means of a right inferioralveolar nerve block. The toothJournal of Oral Implantology 167ARTERIAL SUPPLY OF THE MANDIBLEFIGURE 4. Key: (1) Facial artery. LifeART image copyright (2003), Lippincott WilliamsWilkins. All rights reserved.was sectioned into mesial and distalroots and removed without incident.Upon its removal a bleeding arterioleoriginating from a nutrient canal wasnoted. It originated in the sublingualtissue and passed through the lingualcortical plate into the molar furca. Thelingual aspect of the body of the mandiblewas palpated. At a point near theapical area on the lingual surface of themandible, finger pressure obtundedthe bleeding. Nonetheless, continuedcompression did not maintain hemostasis.Injection of lidocaine with 1:100 000 epinephrine directly into thebleeding nutrient canal was unsuccessful.An unsuccessful effort was madeto ligate the artery before it entered themandible. Because it was positionedtightly against the mandible and cov-168 Vol. XXIX/No. Four/2003ered with a wide band of attached gingivae,there was a risk of damaging theartery with the suture needle at thepoint where the ligation was attempted.Therefore only 1 such attempt wasmade. A 2 3 2 sponge tamponade wasplaced and held under biting pressurefor several minutes, which proved tobe successful in stopping the bleeding.A combination of using the vasoconstrictor,intravascular embolization,and tamponade were probably responsiblefor the cessation of bleeding. Acollagen sponge (Colla-Plug, IntegraLife Sciences, Plainsboro, NJ) was suturedinto the socket with chromic gut.The patient was instructed in postoperativecare and reappointed for follow-up. Healing was uneventful withno recurrence of bleeding.DISCUSSIONThe incident described was relativelyminor; however, it was indicative ofwhat may occur should a larger arterioleor artery be violated. This arterialbleeder was probably a branch of thesubmental artery, the main supplier ofthis area. The nutrient canal may havebeen successfully blocked with a particulatealloplast, xenoplast, or xenograftbrought and compressed into thecanal with a small amalgam carrierand then packed with a small amalgamcondenser.Tamponade over extended periodsof time (15 minutes or more) is of significantvalue and is usually the firstaction to take. Direct ligation of thebleeding vessel is often the most effectivemeans of stopping arterial bloodflow. Arterial retraction, however, maymake ligation difficult.A torn artery may bleed intermittently,whereas a severed artery maystop bleeding by retraction but laterbleed again. If the bleeding cannot becontrolled, a determination as to theorigin of the branch is required. Becauseof anatomic variations in thismidbody, lingual, mandibular location,the possible origin of the bleedershould include the mylohyoid, sublingual,and submental arteries. Digitalpalpation may indicate the originatingbranch. A decision then must be madeas to the feasibility of ligating thebranch itself, which may originate fromthe mylohyoid, facial, or lingual arteries.If it were a branch of the submentalartery, that branch or the facial arteryitself would need to be ligated. If thebleeding continued after that, the lingualartery would require ligation.Life-threatening upper airway obstructionfrom hemorrhage has beenreported from situations includingpuncture wound of the tongue, headtrauma, biopsy of a floor of the mouthlesion, and the severance of an arterysupplying the mandible during an implantprocedure.2-6 Interestingly, tissueplasminogen activator, a thrombolyticagent, has been reported to causebleeding from a branch of the lingualartery.7FIGURE 5. Key: (1) External carotid artery; (2) maxillary artery; (3) inferior alveolar artery.LifeART image copyright (2003), Lippincott Williams Wilkins. All rights reserved.The facial artery is a major extraosseoussource of blood supply to thebody of the mandible and its periosteum.8 Doppler ultrasound studiesshowed that reverse flow of the facialartery was observed by applying manualpressure to the lower border of themandible.9 This indicates significantblood flow from anastomoses withother arteries, so a ligation may not seriouslycompromise the tissue supplied,but a cut facial artery may havesignificant bleeding from both proximaland distal ends. Ligation of thedistal end may need to be consideredas well.The mylohyoid branch of the inferioralveolar artery can be severed byan implant that perforates the mandibularlingual cortex in the molar region.Bleeding control may best be accomplishedwith finger pressure againstthe medial side of the mandible justdistal to the root of the third molar. Ligationof this artery may be practicallyimpossible in an emergency. A dissectionover the artery may incur furtherdamage and exacerbate the situation.The mandibular canal is usually locatedto the lingual side and close tothe inferior border of the mandible.The inferior alveolar artery is usuallylocated superior to the mandibularnerve in the mandibular canal in themolar region.10 An osteotomy that entersthe mandibular canal would probablyfirst sever the artery before contactingthe nerve. During surgery inthis area, arterial bleeding from the osteotomymay indicate violation of themandibular canal and the inferior alveolarartery but may not be a violationof the nerve. However, the loss ofthe neural blood supply or an intraneuralhematoma may result in a neuropathyof the inferior alveolar nerve.Dennis FlanaganThe lingual artery seems fairly resistantto atherosclerosis and can maintaina robust blood flow even in agingpatients. Severing a branch may be aserious event. If a branch of the lingualartery is severed, a ligation of the lingualartery as it courses through Pirogoff'sTriangle may be performed. Thisanatomical triangle is a subdivision ofthe submandibular or digastric triangle.It is bordered by the hypoglossalnerve superiorly, the posterior marginof the mylohyoid muscle anteriorly,and the posterior belly of the digastricmuscle posteriorly with the floorformed by the hyoglossus muscle. Pirogoff'sTriangle has been reported tobe present in 58.2% of dissections. Thelingual artery was found deep to thedigastric tendon and superior to thehyoid bone in 67% of the dissectionsstudied.The lingual artery may be ligatedextraorally.11,12 Because the submentalartery may anastomose with the lingual(sublingual) artery, a severance ofthis artery may require controlling theblood flow of both.A ruptured lingual artery cancause a sudden swelling in the submandibulararea, dislocate the tracheato the contralateral side, and compromisethe airway.13 Pseudoaneurysms(dilations or cavities of the artery, alsocalled pulsatile hematomas) of the lingualartery that may be responsible forhemorrhage if damaged during implantsurgery have been reported.14The lingual artery becomes more tortuouswith age.15 Also, it has been reportedthat with age the lingual arterymay show rupture and proliferation ofintimal elastic fiber. A decrease of thearea of the lumen in relation to the totalarea of the cross section of the arteryoccurs with advancing age aswell.16 Therefore, the media and intimaof the lingual artery thicken by fibrosisoutwardly, but only after about age 60does the lumen decrease in cross section.17The anastomoses of the lingual arterywith its contralateral mate occurthroughout the tongue, with the num-Journal of Oral Implantology 169ARTERIAL SUPPLY OF THE MANDIBLEFIGURE 6. Key: (1) Facial artery; (2) posterior belly of the digastric muscle; (3) submental artery; (4) mylohyoid muscle; (5) mylohyoidnerve. LifeART image copyright (2003), Lippincott Williams Wilkins. All rights reserved.ber of connections increasing as the arteryprogresses to its tip.18The blood supply of the floor of themouth and lingual gingiva can be offeredby the sublingual or the submentalartery. These are branches of thelingual and facial arteries, respectively.The submental artery may be consideredthe main blood supply of thisarea, since in 53% of the cases studied,the sublingual artery was small, insignificant,or absent.19 Hemorrhage inthis area may be assessed by first identifyingthe trunk that supplies thebleeding branch. This can be determinedby applying broad pressure tothe lower medial border of the mandibleor bimanual digital compressionat the site where the facial artery crossesand the submental artery originates(Figures 2 and 6). A cessation or attenuationof bleeding may indicate thatthe bleeding branch is from the sub-170 Vol. XXIX/No. Four/2003mental or facial artery, and ligationhere may be indicated. Otherwise, ligationof the lingual artery may be indicated.However, anastomoses mayindicate the need for ligation of boththe facial and lingual arteries.Apparently severance of these arterialbranches during implant surgery,although relatively small, can cause exsanguinationquickly, and therefore thepatient's life may be threatened. Thesearteries are usually in the range of 1 to2 mm internal diameter of the lumen.A simple calculation shows that at anestimated blood flow from the cut endof an artery of 0.2 mL per beat at 70beats/min, it is possible for 14 mL ofblood to escape in 60 seconds. In 30minutes an estimated 420 mL could belost, the approximate volume of agrapefruit. This amount of blood mayaccumulate in a submandibular spaceto compromise the airway. A sign ofimpending distress is a protrudingtongue. The tongue and epiglottis maybe forced into the pharynx and larynx,closing off the trachea.Because there are many anastomosesin this area among branches of thelingual, facial, and mylohyoid arteries,consideration must be given as towhere bleeding may be arrested.When cut, many arteries stopbleeding with pressure applied at thecut end. It has been shown as well thatarteriole constriction can be producedby hypovolemia, an undesirable condition.20Electrocautery, laser, argon beamcoagulators, the harmonic scalpel (ultrasonicfrictional heating), and vasoconstrictivemedications can also beused to stop bleeding.21-25 In addition,ice-pack compress has been used to aidcessation of a bleeding lingual arteryFIGURE 7. Key: (1) Facial artery; (2) hypoglossal nerve; (3) lingual artery; (4) hypoglossus muscle; (5) posterior belly of the digastricmuscle;(6) hyoid bone; (7) geniohyoid muscle; (8) sublingual artery; (9) genioglossus muscle; (10) lingual nerve. LifeART image copyright (2003),Lippincott Williams Wilkins. All rights reserved.(C. Lindquist DDS, oral communication).A submandibular approach may benecessary for ligation of the lingualand/or facial arteries. This is accomplishedby making an incision 2 fingerbreadths (35-40 mm) medial to (below)the inferior border of the mandible. Accessto the capsule of the submandibulargland is made by dissectionthrough the platysma muscle and thesuperficial layer of the deep cervicalfascia. The gland is mobilized for retraction.The facial artery now may belocated, and care should be taken notto injure the now-exposed facial arteryand vein. The submental arterybranches off at the submandibulargland and is located about 37 mm posteriorto the menton (Figures 2, 4, 7,and 8). Ligation by compression of thesubmental artery at a point here maybe considered. If bleeding is not arrested,then these vessels can be carefullyretracted superiorly with thegland. Both bellies and the tendon ofthe digastric muscle, hypoglossalnerve, and vein are usually apparent.The hyoglossus muscle provides thefloor for these structures. Its fibers runmore vertical, are more delicate, andare deeper colored than the nearbymylohyoid muscle. The hyoglossusmuscle can now be split apart to exposethe lingual artery below for ligation.It may be visible for a short distancebefore it passes deep to the hyoglossusmuscle. In most cases the lingualartery will be inferior or deep tothe superior border of the digastric tendon(which can be 4-10 mm wide) andabout 2 to 4.5 mm inferior or deep tothe hypoglossal nerve. The lingual arteryis usually about 3 to 10 mm abovethe hyoid bone.The sublingual artery may be ligat-Dennis Flanaganed as it runs at the forward edge of thehyoglossus muscle. If access is made superiorof the hypoglossal nerve, then thelingual vein (venae comitans) may befound, which sometimes may be bifurcatedon either or both sides of the hyoglossusmuscle. There is anatomical variationin this area, which may find thelingual artery superficial to the hyoglossusmuscle.12 In the case of floor ofthe mouth bleeding, the submental orfacial artery should be ligated first, andthen the lingual artery ligated if bleedingis not arrested.The sublingual artery is the continuanceof the lingual artery and coursesbetween the genioglossus muscle andthe sublingual salivary gland before itgoes superficially just beneath the mucousmembrane of the floor of themouth, which may allow easier surgicalaccess for ligation in a more anteriorseverance.26 This submandibular li-Journal of Oral Implantology 171ARTERIAL SUPPLY OF THE MANDIBLEFIGURES 8-9. FIGURE 8. Key: (1) Inferior alveolar and mylohyoid arteries; (2) facial artery; (3) mylohyoid muscle. FIGURE 9. A misdirectedosteotomy may perforate the mandibular cortex. LifeART image copyright (2003), Lippincott Williams Wilkins. All rights reserved.gation procedure is intricate and complexand may be best performed by anexperienced head and neck surgeon.An emergency access airway mayneed to be considered in the event of asudden and excessive hemorrhage or ifextreme distortion of the area precludesa surgical entry for ligation. Onereport stated significant swelling in 2minutes of perforating the sublingualartery.27 An emergency cricothyrotomycan be made by a transverse incisionclose to the upper rim of the cricoidcartilage to avoid the branch of the cricothyroidartery. However, this incisionmust be carried through the conuselasticus and is close to the vocal cords.This may result in a subsequent laryngealscarring and stenosis and is notconsidered safe. Another entry belowthe thyroid and cricoid cartilages, atabout the fourth, fifth, and sixth trachealrings or behind the thyroid isthmusat the second, third, and fourthrings can be done. Below the level ofthe thyroid, the trachea is deeper andlarge vessels may be present. A penetration1 cm below the cricoid cartilagebetween the second and third cartilagerings may be the best emergency entry172 Vol. XXIX/No. Four/2003point. Insertion of a 13-gauge needlemay provide an adequate opening untila tracheostomy can be done. Thethyroid isthmus is usually below thefirst 2 tracheal cartilage rings, and nolarge blood vessels are usually presentat this level, although the inferior thyroidvein may run in front of the tracheahere.26,28 This vein may be palpatedwith the fingertip and pushed to 1side with finger pressure to prevent itsseverance with the initial incision.The cross-sectional shape of themandible makes it more likely for a lingualcortical perforation than a facialperforation. However, the implant surgeonmust always be aware of aberrantosseous contours. Palpation of theridge contour, computerized tomograms,magnetic resonance imaging,and bone-sounding techniques arehelpful in avoiding a cortical perforation.29 Palpation of the ridge during theosteotomy may help prevent an adverseevent. In-office emergency kitsfor maintaining an airway are a requirementfor the implant surgeon.SUMMARYThere are 3 important arteries thatsupply the mandible and are importantconsiderations for dental implantsurgery: the inferior alveolar (and itsbranch, the mylohyoid); the facial (itsbranch, the submental artery); and thelingual (its branch, the sublingual artery).A misdirected osteotomy thatpenetrates the mandibular cortex maysever a branch of 1 of these and possiblycreate a life-threatening situation(Figure 9). An atrophic edentulousridge may allow these arteries to lieagainst the mandible.A bleeding artery at the lingualsurface of the posterior mandible maybe the mylohyoid artery and possiblybe controlled by applying finger pressureto that site and/or pressure at thebleeding point until it stops. Ligationof this artery may be difficult or impossible.A bleeding artery at the middlelingual of the mandible may becaused by a severance of the submentalartery and require control of the facialand lingual arteries by surgical ligation.Since it is very common for thesubmental, sublingual, and mylohyoidarteries to anastomose among themselvesand anatomic variation is notuncommon, control of a severed arteryin this area may become a serious com-plication. Arterial bleeding at the lingualof the anterior mandible may becaused by a terminal branch of the sublingualor submental arteries. Theseterminal arteries are usually of smalldiameter and may be controlled at thecut end by compression, vasoconstrictiveinjections, cautery, or ligation. Ableeding artery on the facial aspect ofthe mandible, which may be the facialartery or a branch, may be controlledby compression or finger pressure atthe inferior border of the mandible, orit may require surgical ligation. Arterialretraction may preclude local ligation.Implants of less than 14 mm inlength have been recommended for usein the mandible to lessen the likelihoodof perforations.5The implant surgeon should considermaintaining relationships withappropriate specialists who may becalled to intervene in such instances. Itis imperative, however, that the implantsurgeon acquire an in-depth understandingof the arterial supply ofthe mandible and the techniques requiredto obtund bleeding and maintainan airway. As soon as a bleedingevent is realized, an immediate tamponadeshould be applied to the areaand a laryngeal airway should be consideredto preclude a later forced installation.Immediate hospitalizationmay be necessary.REFERENCES1. Goss CM, ed. The arteries. In:Gray's Anatomy: Anatomy of the HumanBody. 2nd ed. Philadelphia: Lea Febiger;1967: 583-592.2. Kattan B, Snyder HS. Lingualartery hematoma resulting in upperairway obstruction. J Emerg Med. 1991;9:421-424.3. Chase CR, Hebert JC, FarnhamJE. Post-traumatic upper airway obstructionsecondary to a lingual arteryhematoma. J Trauma. 1987;27:953-954.4. Burke RH, Masch GL. Lingualartery hemorrhage. Oral Surg Oral MedOral Pathol. 1986;62:258-261.5. Givol N, Chaushu G, Halamish-Shani T, Taicher S. Emergency tracheostomyfollowing life-threatening hemorrhagein the floor of the mouth duringimmediate implant placement inthe mandibular canine region. J Periodontol.2000;71:1893-1895.6. Mason ME, Triplett RG, AlfonsoWF. 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Near-fatal airway obstructionafter routine implant placement.Oral Surg Oral Med Oral PatholOral Radiol Endodontol. 2001;92:597-600.28. Goss CM, ed. Trachea andbranch. In: Gray's Anatomy: Anatomy ofthe Human Body. 2nd ed. Philadelphia:Lea Febiger; 1967:1137.29. Flanagan DF. A method for estimatingpreoperative bone volume forimplant surgery. J Oral Implantol. 2000;26:262-266.