Introduction The third molar has been the most widelydiscussed tooth in the dental literature, and thedebatable question “….. to extract or not toextract” seems set to run into the next century. -Faiez N. Hattab, JOMS, 57: 389-391 (1999)
Theories of impactionBy Durbeck1) Orthodontic theory : Jaws develop in downward andforward direction. Growth of the jaw and movement ofteeth occurs in forward direction,so any thing that interferewith such moment will cause an impaction (small jaw-decreased space).A dense bone decreases the movement of the teeth inforward direction.
Theories of impaction2) Phylogenic theory: Nature tries to eliminate the disused organsi.e., use makes the organ develop better, disuse causes slowregression of organ.[More-functional masticatory force – better the development ofthe jaw]Due to changing nutritional habits of our civilization, use oflarge powerful jaws have been practically eliminated.Thus, over centuries the mandible and maxilla decreased in sizeleaving insufficient room for third molars.
Theories of impaction3) Mendelian theory: Heredity is most common cause. Thehereditary transmission of small jaws and large teethfrom parents to siblings. This may be importantetiological factor in the occurrence of impaction.4) Pathological theory: Chronic infections affecting anindividual may bring the condensation of osseous tissuefurther preventing the growth and development of thejaws.5) Endocrinal theory: Increase or decrease in growthhormone secretion may affect the size of the jaws
What will happen if impact teeth are retained?ComplicationsInfections: Pericoronal infection Acute / chronic alveolarabscesses Chronic suppurativeosteitis Necrosis Osteomyelitis
ComplicationsPain: Slight and restricted Severe or excruciating Intermittent, constant orperiodic Referred to ear, the postauricular area, any part ofthe area supplied by thetrigeminal nerve. (Eg.Temporal pain)
Fractures: Impacted tooth proves that weakening of the mandible occurs dueto displacement of bone.Other complications: Ringing, singing or buzzing sound in the ear (Tinnitus aurium) Otitis Affections of the eye such as Dimness of the vision Blindness Iritis Pain simulating that of glaucoma
Indications and contraindications for removalof impacted tooth“A strong indication for removal of impacted thirdmolar should be complemented with a strongcontraindication to its retention”– Mercier P., Precious D., Risk and benefits of removal of impacted third molars,IJOMS 21:17, 1992.Indications: Pericoronitis – 27% to 34% (Swed Den J1987) Caries – 3% to 15% (IJOMS 1988) Root resorption – 5% (Swed Den J 1987) Formation of follicular cyst – 1 to 5%(J Oral Pathol1998) Tumors arising in the follicular (Dentigerous cysts) – 0.1to 0.2% (JOMS 1991)
Contraindications: Acute infection with pericoronitis Medically compromised state – uncontrolled diabetes Extremes of age – Old age
Historical background on the criteria forremoval of third molarHistorical background In 1979, a consensus development conferencepracticing dentists and scientists, on thirdmolar removal was sponsored by NationalInstitute of Health, USA *. * -J Oral Surgery…Vol38,March 1980
ClassificationAccording to Long axis of the impacted tooth in relation to the long axisof the 2nd molar Winter’s classification (1926)
Pell & Gregorys classification (1933)Position APosition BPosition C
Based on Relationship of the Tooth to theAnterior Border of the Ramus of the MandibleClass I Class II Class III
According to Supero-Inferior Positionof 3rd Molar Crown to crown Crown to cervix Crown to root
Killey & Kay’s Classificationa) Based on angulation and position:(Same as Winter’s classification)b) Based on the state of eruption: - Completely erupted- Partially erupted- Uneruptedc) Based on roots: 1) Number of roots - Fused roots- Two roots- Multiple roots2) Root pattern - Surgically favorable- Surgically unfavorable
ADA code on Procedures and Nomenclature The American Dental Association (ADA) Code describesthe amount of soft and hard tissues over the coronalsurface of an impacted tooth. These are described as: soft tissue impactions, partial bonyimpactions, completely bony impactions, and completelybony impactions with unusual surgical complications.
Combined ADA and AAOMS Classification soft tissue impaction (incision of overlying soft tissue & removal oftooth) partial bony impaction (incision of overlying soft tissue, elevation offlap, either removal of bone & tooth or sectioning & removal of tooth) complete bony impaction (incision of overlying soft tissue, elevation offlap, removal of bone & sectioning of tooth for removal) complete bony impaction with unusual surgical complication (incision ofoverlying soft tissue, elevation of flap, removal of bone, sectioning oftooth for removal &/or presents unusual difficulties & circumstances)
Pre-Operative Assessment HISTORY Patients might be asymptomatic when symptomatic- pain, swelling of the face, trismus Symptoms of acute pulpitis or abscess In denture wearers if denture no longer fits & at the same time show thesymptoms of pericoronitis. General medical history & assessment of physical condition EXAMINATIONClinical Extra oral Intra oralRadiographs DECISIONDiagnosisTreatment planning – type of anesthesia- surgical procedure
Local Examination EXTRA ORAL:• Signs of swelling & redness of the cheek• LN’s - enlargment & tenderness,• TMJ• Anesthesia or paraesthesia of lower lip, INTRA ORAL:• Mouth opening & any evidence of trismus• State of eruption of tooth, signs of pericoronitis• Condition of 1st & 2nd molars• Space present b/w 2nd M & ascending ramus• Elasticity of oral tissues• Size of tongue
Radiographs Periapical film OPG Occlusal film1. Access2. Position & depth (WAR lines)3. Shape of the crown4. Texture of investing bone5. Position & root pattern of 2nd Molar & impacted tooth6. Inferior alveolar canal7. External oblique ridge --vertical & ant. to third molar – poor access-- oblique & post. – good accessInterpretation
Relationship of Root to CanalRelated but not involving the canalSeparatedAdjacentSuperimposedRelated to changes in the rootsDarkening of rootDark and bifid rootNarrowing of rootDeflected rootRelated with changes in the canalInterruption of linesConverging canalDiverted canal
Relationship of Inferior Alveolar Nerve to theRoots of Third MolarDarkening of root Deflection of root Narrowing of canal Dark & Bifid apexRoods Radiographic Criteria
WAR (Winter’s) LinesWhite line amber line red line Red line <5mm: extraction - easy, there after every 1mm increase indepth increases the difficulty three folds & if it is >9mm then plan thesurgery under GA. As a general rule DA teeth are more difficult than MA impaction ofsimilar depth & root pattern
DIFFICULTY INDEX :Category ValuesSpatial relationship Mesioangular1Horizontal2Vertical3Distoangular4Depth Level A1Level B2Level C3Ramus relationship Class I1Class II2Class III3
Category Score1. Winters classification HorizontalDistoangularMesioangularVertical22102. Height of mandible 1-30mm31-34mm35-39mm0123. Angulation of 3rd molar 1 - 5060 - 6970 -7980 - 8990 +012344. Root shape ComplexFavourable curvatureUnfavourable curvature1235. Follicles NormalPossibly enlargedEnlarged0126. Path of exit Space availableDistal cusp coveredMesial cusp coveredBoth cusp covered0123Total 33WHARFE’s ASSESSMENT by McGregor (1985)
Surgical ManagementJohn Tomes (1849) – first to describe surgical accessSteps in surgical removalAnesthesiaIncision and mucoperiosteal flapRemoval of boneTooth removalWound debridementArrest of haemorrhageWound closurePostoperative follow-up
Surgical Anatomy Location: lower 3rd molar is situatedat the distal end of the body of themandible where it meets a relativelythin ramus. Embedded b/w thick buccal alv bonebuttressed by external oblique ridge &the narrow inner cortical plate. Ramus offset by 20° Retro Molar triangle- depressedroughned area post. to 3rd molar
Muscles: Vestibule is formed by the attachment of buccinator buccally and mylohyoidlingually. Along the anterior border of the ramus - tendinous insertion of temporalis Excessivestripping of these muscle will cause hematoma, pain and trismus. Lingual pouch – perforation of roots along the lingual cortical plate.- may cause # of lingual cortical plate-displacement of fractured root fragments below the mylohyoid
Arteries• Facial artery & facial vein run in close approximation with lower 2ndmolar near the anterior border of masseter.• Mandibular vessels in retro molar triangle which supply temporalistendon.• Hemorrhage can occur during surgical removal of impacted tooth ifdistal incision is not taken laterally towards cheek.
Inferior Alveolar Nerve• Lies just below the roots of mandibularmolars but slightly buccally placed ininferior dental canal.• In case of deep seated impaction special care should be taken toprotect this neurovascular bundle during bone drilling & toothsectioning.• Calcification of inferior alveolar canal is completed before the roots of3rd molar are formed. Thus growing roots may impinge upon thecanal or get deflected. So blind elevation is not advisable.
MUCOPERIOSTEAL FLAPIncision – 3 parts: Anterior, posterior & intermediate limbNot to be extended too distally-Bleeding from buccal vessels & other arteriesPostoperative trismus – temporalis muscle damageHerniation of buccal fat padDamage to lingual nerve (lingual extention)
Factors Governing Planning of IncisionSurgical accessHealing of sutured wound – dry socketPeriodontal health of II molar – distal pocketSuture line must rest on normal bonePartly visible crown: de-epitheliazation
Bone RemovalAim1. To expose the crown by removing the bone overlying it.2. To remove the bone obstructing the pathway forremoval of the impacted tooth.Types1. By consecutive sweeping action of bur (in layers).2. By chisel or osteotomy cut (in sections).How much bone has to be removed?1. Bone should be removed till we reach below the height of contour, wherewe can apply the elevator.2. Extensive bone removal can be minimized by tooth sectioning.
Sl.No Criteria. Chisel&Mallet Bur1. Technique Difficult Easy.2. Control over bone cutting Uncontrolled Controlled.3. Patient acceptance. Not tolerated inL.A.Well tolerated inL.A.4. Healing of bone. Good Delayed Healing5. Postoperative edema Less More.6. Dry socket. Less. More.7. Postoperative Infection. Less. More.Chisel v/s Bur
Bone Removal TechniquesMoore & Gillbe’s Collar Technique- Conventional tech of using bur.- Rosehead round bur no.3 is used to create a gutter along thebuccal side & distal aspect of tooth.- A point of elevation is created with bur.- Amount of bone sacrificed is less.- Can be used in old patient.- Convenient for patient.
Split Bone / Lingual Split TechniqueSir William Kelsey Fry(1933)- Quick & clean tech- Reduces the size of blood clot by means of saucerizationof socket.- Decreased risk of damage to the periodontium of the secondmolar.- Less risk of inferior alveolar nerve damage.- Decreased risk of socket healing problems- Can use regional anaesthesia but endotracheal anaesthesia ispreferred one.- Only suitable for young adults whose bone is elastic- Inconvenience to patients due to chisel useage.
Vertical stop cutSplit of Distolingual boneElevationHorizontal cutRemoval of distal& buccal boneRemoval of distolingual boneIncisionClosure
Tooth Division“Rationale of tooth sectioning is to create a space into which impacted tooth canbe displaced & thence removed.”Tooth is sectioned in various ways depending on the type & degree of impaction.Mesioangular Impaction Horizontal Impaction
Debridement of Wound & Closure Thorough debridement of the socket by Periapical curettage. Smoothening of sharp bony margins by Bone file / burs. Thorough irrigation of the socket Betadine solution + Saline . Initial wound closure is achieved by placing 1stsuture just distal to2ndmolar, sufficient number of sutures to get a proper closure.
Post Operative Instructions Pressure pack – 1hr Ice application Soft diet –1st two days 1st dose of analgesic should be taken before the anesthetic effect of LAwears off. Avoid strenuous exercises for 1st 24 hrs. Avoid gargling / spitting / smoking / drinking with straw. Warm water saline gargling after 24 hrs + mouth wash regularlythereafter. Suture removal on 5th POD.
ComplicationsIntra Operative1. During incisiona. Injury to facial arteryb. Injury to lingual nervec. Hemorrhage – careful history2. During bone removala. Damage to second molarb. Slipping of bur into soft tissue & causing injuryc. Extra oral/ mucosal burnsd. Fracture of the mandible when using chisel & mallete. Subcutaneous emphysema3. During elevation or tooth removala. Luxation of neighbouring tooth/ fractured restorationb. Soft tissue injury due to slipping of elevatorc. Injury to inferior alveolar neurovascular bundled. Fracture of mandiblee. Forcing tooth root into submandibular space or inferioralveolar nerve canalf. Breakage of instrumentsg. TMJ Dislocation – careful history
Nerve Injuries 0.6-5% of all the third molar surgeries are involved with nervedamages of which 0.2% are irreversible IAN: immediate disturbance - 4-5% (1.3-7.8%)permanent disturbances - <1% (0-2.2%) Lingual N: immediate - 0.2-22%permanent - 0-2% 96% IAN injuries show spontaneous recovery within 9 months,better than lingual nerve which is about 87% Beyond 2yrs recovery is unlikely
Dry Socket 20% of extraction of mandibular 3rd molar 2% of routine extraction Moderate-severe pain develops generally on 3rd/4th day.(with no signsof infection) Dull aching pain usually radiates to ear Empty socket Bad odour & taste Etiology - unknown Possibly excessive fibrinolytic activity Subclinical infection
Management Gentle irrigation with warm saline followed by superficial suctioning. Pack iodoform gauze socked with medications change every day for 3-6days. Intra-alveolar medicaments(controversial)-with eugenol-topical LA-antifibrinolytic agents. Analgesics.