Mandibular 3rd molar impactions

Mandibular 3rd molar impactions Mohammad akheel Omfs pg IntroductionThe third molar has been the most widely discussed tooth in the dental literature, and the debatable question .. to extract or not to extract 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 and forward direction. Growth of the jaw and movement of teeth occurs in forward direction,so any thing that interfere with such moment will cause an impaction (small jaw-decreased space).A dense bone decreases the movement of the teeth in forward direction.

Theories of impaction2) Phylogenic theory: Nature tries to eliminate the disused organs i.e., use makes the organ develop better, disuse causes slow regression of organ.[More-functional masticatory force better the development of the jaw]Due to changing nutritional habits of our civilization, use of large powerful jaws have been practically eliminated. Thus, over centuries the mandible and maxilla decreased in size leaving insufficient room for third molars. Theories of impaction3) Mendelian theory: Heredity is most common cause. The hereditary transmission of small jaws and large teeth from parents to siblings. This may be important etiological factor in the occurrence of impaction. 4) Pathological theory: Chronic infections affecting an individual may bring the condensation of osseous tissue further preventing the growth and development of the jaws. 5) Endocrinal theory: Increase or decrease in growth hormone secretion may affect the size of the jawsWhat will happen if impact teeth are retained? ComplicationsInfections: Pericoronal infection Acute / chronic alveolar abscesses Chronic suppurative osteitisNecrosisOsteomyelitis

ComplicationsPain:Slight and restrictedSevere or excruciating Intermittent, constant or periodicReferred to ear, the post auricular area, any part of the area supplied by the trigeminal nerve. (Eg. Temporal pain)

Fractures:Impacted tooth proves that weakening of the mandible occurs due to displacement of bone. Other complications: Ringing, singing or buzzing sound in the ear (Tinnitus aurium)OtitisAffections of the eye such asDimness of the visionBlindnessIritisPain simulating that of glaucomaIndications and contraindications for removal of impacted tooth A strong indication for removal of impacted third molar should be complemented with a strong contraindication 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 Pathol 1998)Tumors arising in the follicular (Dentigerous cysts) 0.1 to 0.2% (JOMS 1991)Contraindications:Acute infection with pericoronitisMedically compromised state uncontrolled diabetesExtremes of age Old ageHistorical background on the criteria for removal of third molarHistorical background In 1979, a consensus development conference practicing dentists and scientists, on third molar removal was sponsored by National Institute of Health, USA *.* -J Oral SurgeryVol38,March 1980 Classification

According to Long axis of the impacted tooth in relation to the long axis of the 2nd molar Winters classification (1926) 12

Mesioangular Vertical Distoangular Pell & Gregory's classification (1933)Position A

Position BPosition C14 Based on Relationship of the Tooth to the Anterior Border of the Ramus of the Mandible Class I Class II Class III

15According to Supero-Inferior Position of 3rd Molar

Crown to crown

Crown to cervix

Crown to root

Killey & Kays Classification

a) Based on angulation and position: (Same as Winters classification)

b) Based on the state of eruption: - Completely erupted - Partially erupted - Unerupted

c) Based on roots: 1) Number of roots - Fused roots - Two roots - Multiple roots 2) Root pattern - Surgically favorable - Surgically unfavorable17ADA code on Procedures and NomenclatureThe American Dental Association (ADA) Code describes the amount of soft and hard tissues over the coronal surface of an impacted tooth. These are described as: soft tissue impactions, partial bony impactions, completely bony impactions, and completely bony impactions with unusual surgical complications.

Combined ADA and AAOMS Classification soft tissue impaction (incision of overlying soft tissue & removal of tooth) partial bony impaction (incision of overlying soft tissue, elevation of flap, either removal of bone & tooth or sectioning & removal of tooth) complete bony impaction (incision of overlying soft tissue, elevation of flap, removal of bone & sectioning of tooth for removal) complete bony impaction with unusual surgical complication (incision of overlying soft tissue, elevation of flap, removal of bone, sectioning of tooth for removal &/or presents unusual difficulties & circumstances)19Pre-Operative AssessmentHISTORYPatients might be asymptomaticwhen symptomatic- pain, swelling of the face, trismusSymptoms of acute pulpitis or abscessIn denture wearers if denture no longer fits & at the same time show the symptoms of pericoronitis.General medical history & assessment of physical condition

EXAMINATION Clinical Extra oralIntra oral Radiographs

DECISION Diagnosis Treatment planning type of anesthesia - surgical procedureLocal ExaminationEXTRA ORAL: Signs of swelling & redness of the cheek LNs - enlargment & tenderness,TMJAnesthesia or paraesthesia of lower lip,INTRA ORAL:Mouth opening & any evidence of trismusState of eruption of tooth, signs of pericoronitisCondition of 1st & 2nd molarsSpace present b/w 2nd M & ascending ramusElasticity of oral tissuesSize of tongue

21RadiographsPeriapical filmOPGOcclusal film

1. Access 2. 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 22Relationship of Root to Canal

Related but not involving the canal

SeparatedAdjacentSuperimposed

Related to changes in the roots

Darkening of rootDark and bifid rootNarrowing of rootDeflected root

Related with changes in the canal

Interruption of linesConverging canalDiverted canal Relationship of Inferior Alveolar Nerve to the Roots of Third Molar

Darkening of root Deflection of root Narrowing of canal Dark & Bifid apex

Roods Radiographic CriteriaWAR (Winters) Lines White line amber line red line Red line 9mm then plan the surgery under GA.As a general rule DA teeth are more difficult than MA impaction of similar depth & root pattern

25DIFFICULTY INDEX : CategoryValuesSpatial relationship Mesioangular

1 Horizontal

2 Vertical

3 Distoangular 4 Depth Level A 1 Level B 2 Level C 3Ramus relationship Class I 1 Class II 2 Class III 326

Category

Score

1. Winters classification

HorizontalDistoangularMesioangularVertical

2210

2. Height of mandible

1-30mm31-34mm35-39mm

012

3. Angulation of 3rd molar

1 - 5060 - 6970 -7980 - 8990+

01234

4. Root shape

ComplexFavourable curvatureUnfavourable curvature

123

5. Follicles

NormalPossibly enlargedEnlarged

012

6. Path of exit

Space availableDistal cusp coveredMesial cusp coveredBoth cusp covered

0123

Total

33

WHARFEs ASSESSMENT by McGregor (1985)27Surgical Management

John Tomes (1849) first to describe surgical access

Steps in surgical removal

AnesthesiaIncision and mucoperiosteal flapRemoval of boneTooth removalWound debridementArrest of haemorrhageWound closurePostoperative follow-upSurgical AnatomyLocation: lower 3rd molar is situated at the distal end of the body of the mandible where it meets a relatively thin ramus. Embedded b/w thick buccal alv bone buttressed by external oblique ridge & the narrow inner cortical plate.Ramus offset by 20Retro Molar triangle- depressed roughned area post. to 3rd molar

29Muscles: Vestibule is formed by the attachment of buccinator buccally and mylohyoid lingually. Along the anterior border of the ramus - tendinous insertion of temporalis Excessive stripping 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

30Arteries Facial artery & facial vein run in close approximation with lower 2nd molar near the anterior border of masseter.Mandibular vessels in retro molar triangle which supply temporalis tendon.Hemorrhage can occur during surgical removal of impacted tooth if distal incision is not taken laterally towards cheek.

31Inferior Alveolar NerveLies just below the roots of mandibular molars but slightly buccally placed in inferior dental canal.In case of deep seated impaction special care should be taken to protect this neurovascular bundle during bone drilling & tooth sectioning.Calcification of inferior alveolar canal is completed before the roots of 3rd molar are formed. Thus growing roots may impinge upon the canal or get deflected. So blind elevation is not advisable.

32MUCOPERIOSTEAL FLAP

Incision 3 parts: Anterior, posterior & intermediate limb

Not 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 Incision

Surgical accessHealing of sutured wound dry socket Periodontal health of II molar distal pocketSuture line must rest on normal bonePartly visible crown: de-epitheliazation

Types of Flaps

L shaped flap (2nd molar para marginal Flap with vestibular extension)

Envelope flap(2nd molar sulcus incision)

Bayonet shaped flap(2nd molar sulcus incision With vestibular extension)

Buccal extension flapTriangular flap

Wards incision Modified Wards incisionBone RemovalAim

1. To expose the crown by removing the bone overlying it.2. To remove the bone obstructing the pathway for removal 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, where we can apply the elevator.2.Extensive bone removal can be minimized by tooth sectioning.

Sl.No

Criteria.

Chisel&Mallet

Bur

1.

Technique

Difficult

Easy.

2.

Control over bone cutting

Uncontrolled

Controlled.

3.

Patient acceptance.

Not tolerated in L.A.

Well tolerated in L.A.

4.

Healing of bone.

Good

Delayed Healing

5.

Postoperative edema

Less

More.

6.

Dry socket.

Less.

More.

7.

Postoperative Infection.

Less.

More.

Chisel v/s BurBone Removal TechniquesMoore & Gillbes Collar Technique Conventional tech of using bur. Rosehead round bur no.3 is used to create a gutter along the buccal 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.

39Split Bone / Lingual Split Technique Sir William Kelsey Fry(1933)

- Quick & clean tech- Reduces the size of blood clot by means of saucerization of socket.- Decreased risk of damage to the periodontium of the second molar.- Less risk of inferior alveolar nerve damage.- Decreased risk of socket healing problems- Can use regional anaesthesia but endotracheal anaesthesia is preferred one. - Only suitable for young adults whose bone is elastic- Inconvenience to patients due to chisel useage.40

Vertical stop cutSplit of Distolingual boneElevationHorizontal cutRemoval of distal & buccal boneRemoval of disto lingual boneIncisionClosure Tooth DivisionRationale of tooth sectioning is to create a space into which impacted tooth can be displaced & thence removed.Tooth is sectioned in various ways depending on the type & degree of impaction.

Mesioangular Impaction

Horizontal Impaction42

Vertical ImpactionDisto Angular ImpactionDebridement of Wound & ClosureThorough 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 to 2ndmolar, sufficient number of sutures to get a proper closure. 44Post Operative InstructionsPressure pack 1hrIce application Soft diet 1st two days1st dose of analgesic should be taken before the anesthetic effect of LA wears off.Avoid strenuous exercises for 1st 24 hrs.Avoid gargling / spitting / smoking / drinking with straw. Warm water saline gargling after 24 hrs + mouth wash regularly thereafter.Suture removal on 5th POD.

45ComplicationsIntra Operative 1. During incision a. Injury to facial arteryb. Injury to lingual nervec. Hemorrhage careful history 2. During bone removal a. Damage to second molar b. Slipping of bur into soft tissue & causing injury c. Extra oral/ mucosal burns d. Fracture of the mandible when using chisel & mallet e. 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 inferior alveolar nerve canalf. Breakage of instrumentsg. TMJ Dislocation careful historyNerve Injuries0.6-5% of all the third molar surgeries are involved with nerve damages of which 0.2% are irreversible

IAN: immediate disturbance - 4-5% (1.3-7.8%) permanent disturbances -