Mandibular 3rd molar impacion

precise presentation for final year bds student

1. MANDIBULAR 3 RD MOLAR IMPACTION- Classification, Surgical procedure & Complication By- resha ghosh ,( final year)

2. INTRODUCTION The term “impaction” originates from a Latin word “ impactus ”(wedged) Prevalence of tooth impaction is a common dental anomaly. The 3 rd molar is the most frequently impacted tooth,with a frequency of occurrence generally reported to be from 16.7% to 68.9%( Queck et al. 2003) They are retained for the patient’s lifetime,unless surgically removed or exposed &brought into alignment by orthodontics. The early detection of tooth impaction is very important from a therapeutic point of view,as the presence of impacted tooth may cause many complications. Frequency of impaction is more in mandible than maxilla.with significantly higher frequency in females than males.

3. DEFINITIONS A. According to WHO: “An impacted tooth is the one that is unable to fully erupt in its normal functional occlusion/location by its expected age of eruption because it is blocked by overlying soft tissue or bone or another tooth.” According to Archer(1975): “An impacted tooth or an embedded tooth is the tooth that has failed to erupt cpmpletely to its correct normal position in the dental arch,and its eruption potential has been lost.” Fully impacted tooth is completely encased in the jaw bone. Partialy impacted tooth is the one, which is not completely encased in the jaw bone and has communication in thhe oral cavity.

4. Causes of Impaction of Teeth 3 rd molar tooth impaction The causes of impaction of teeth are still not clearly understood.They appear to be multifactorial.Currently,insufficient amount of space in the jaw distal to the second molar is considered to be the most significant reason.The incidence of mandibular is nearly(17-32)%. 1.Durbeck orthodontic theory(inadequate space in the dental arch for eruption): Growth of the jaw&teeth occurs in forward direction,any interference in growth pattern will cause impaction because of small jaw with decreasd space. 2.Phylogenic theory(Nodine1943): Due to the evolution over centuries,the human jaw size is becoming smaller than our ape like ancestors,& since the 3 rd molar tooth is last to erupt,there may not be room for it to emerge in the oral cavity.The modern food habits are changed frpm earlier raw,fibrous diet to cooked/processed food,which does not require forceful mastication,which offers less stimulation for jaw growth( disuse theory). 3.Mendelian theory: Here genetic variations/genetics play a major role.If the individual genetically receives a small jaw from one of the patient and/or large teeth from the other parent,then impacted teeth can be seen,because of “lack of space.”

5. Factors responsible for impaction of a tooth (Archer1975)

6. Indications for removal/extraction of impacted 3 rd molar teeth 1.Recurrent pericoronitis / pain: Pericoronitis is an infection with associated inflammation of gingival&contiguous soft tissue,covering the crown of the partially erupted impacted mandibular 3 rd molar and its associated follicle.It is reported to be common in vertical(23%) type of impactions in case of 27 to 34% of patient.3 rd molars with peticoronitis are removed to prevent recurrent episodes of it. 2.Impacted 3 rd molar may decrease the amount of bone on the distal aspect of 2 nd molar & may lead to periodontal defect.25% of patients with aymptomatic 3 rd molars were found to have deep periodontal pocket&attachment loss. Deep periodontal pocket more than or equal to 5mm depth,distal to 2 nd molar associated with partialy erupted 3 rd molar is often difficult to manage. 3.Prevention of root resorption and caries: Caries of the impacted tooth crown&the adjacent tooth at cervical area(3-28%) can be seen due to the accumulation of biofilm& an inability to access and clean the aera.Root resorption of the distal root of the adjacent 2 nd molar is seen usually in 21-30 years of age group(7-24%) due to pressure from the eruptive 3 rd molar&chemical mediators secreted by reduced enamel epithelium.Prophylactic removal of impacted tooth is indicated here.

7. 4.Prior to orthodontic treatment: to control the tooth crowding in the mandible . 5.Prevention or management of cysts and tumors associated with impacted 3 rd molar of odontogenic origin : 1 to 5% chances for cystic changes&tumors may range from 0.1-0.2% from dental follicle.(seen under40 years of age group) 6.Prevention of jaw angle fracture: Sinn et al. reported that impacted or submerged 3 rd molar decreases the amount of bone support & weakens the angle of the mandible.Patient engaged with sports like football,rugby,martial arts etc. may get their impacted 3 rd molars removed to prevent angle fracture. 7.For the preparation of orthognathic surgery: prior to sagittal split osteotomy of ramus in oder to avoid bad split/inadvertent fracture of mandible,lower 3 rd molars extracted at least 1 to 2 months before majort sugery . 8.Management of preprosthetic concerns: Presene of impacted tooth in the residual ridge may cause obstruction to the placement of a partial or complete denture.before the fabrication of the prosthesis, impacted teeth should be removed. 9.Impacted teeth in the line of fracture 10.Buccoversion of partially reupted impacted molars may cause constant trauma to the cheek,leading to ulceration,frictional keratosis or irritational fibroma.

8. Classification of impacted third molars Mandibular impacted 3 rd molar are traditionaly classified radiographycally by angulation,depth&arch length or by relationship to the anterior aspect of the ascendingmandibular ramus. 1.Winter’s classification(1926): A. Angulation : According to the position of the impacted 3 rd molar to the long axix of the 2 nd molar,this classication is suugested for-

9. B.Depth : As per the relationship to the occlusal surface of the adjoining 2 nd molar of the impacted mandibular 3 rd molar,the depth can be judged: Position A: The highest position of the tooth is on a level with or above the occlusal line. Position B: The highest position of the tooth is below the occlusal plane,but above the cervical level of 2 nd molar. Position C: The highest position of the tooth is below the cervical level of the 2 nd molar. 2.Pell and Gregory classification(1933): Relationship of the impacted lower 3 rd molar to the ramus of the mandible &the 2 nd molar[based on the space available distal to the second molar]: CLASS 1: Sufficient space available between the anterior border of the ascending ramus &the distal side of the 2 nd molar for the eruption of the 3 rd molar. CLASS 2: The space available between the anterior border of the ramus & the distal side of the second molar is less than mesiodistal width of the crown of the 3 rd molar,It denotes that,distal portion of the 3 rd molar crown is covered by the bone from the ascending ramus.

10. CLASS 3: The 3 rd molar is totally embedded in the bone from the ascending ramus,because of absolute lack of space

11. 3.Quek et al.(2003)Introduced Measurment Of Angulation of Impaction: Here,the angle is measured by a protractor in degrees formed between the intersected long-axis of the 2 nd and 3 rd molar. Vertical(10-10º) Mesioangular (11-79º)2 Horizontal(80-100º) Distoangular (-11º-79º) Others: Distoangular / mesioangular / horizontally inverted(111ºto-80º)

12. RADIOLOGICAL EXAMINATION OF IMPACTED TEETH 1.Intraoral x-ray: Intraoral x-rays are possible,if tooth is in the alveolus &not in the ramus. Possible if oral opening is adequate. If there is no gagging. Useful to study the relation with adjoining tooth,configuration of the roots& status of the crown. Useful to record the relationship with inferior alveolar canal Tube shift or buccal object rule should be followed for periapical x-rays. 2.Extraoral x rays: Orthopantomogram ( opg ) Lateral oblique view Mandible Indicated in: Patients with restricted oral opening/ treismus /excessive Gagging. To study the relationship of the tooth to the inferior alveolar Nerve(IAN).

13. Multiple impacted teeth Kissing molars Multiple impacted teeth Multiple impacted teeth plus associated keratocyst with impacted lower canine OPG showing bilateral impacted lower 3 rd molar:left 3 rd molar associated with cystic lesion Deep impacted lower 3 rd molar,almost touching the lower border of the mandible&associated with odontome a rare case of impacted 4 th molars;right lower 4 th molar is geminated with 3 rd molar.

14. FACTORS RESPONSIBLE FOR INCREASING THE DIFFICULTY SCORE FOR REMOVAL OF IMPACTED TEETH As per depth As per angulation As per the space available for eruption Crown size Configuration of the roots of the impacted tooth: -length of the roots -root development -curvature of the root -root size 6.Bone texture and density 7.Size of follicular sac(non existent/narrow follicular sac around the crown will require bone cutting Around the crown) 8.Space or contact in relation to mandibular second molar( if the impacted tooth is locked against the crown of the second molar,then sectioning of the tooth should be planned)

15. Related,but non involving the canal Related to change in root Related with changes in canal Close proximity of the root to canal but intervening bone separates the both- 1.separated,2.adjacent,3.superimposed.Trace the outline of the root as well as canal,which will show no disturbance 1Darkening of the root 2.Dark and bifid root 3.Narrowing of the root 4. Deflected root I nterruption(loss of lines)-the dense roof & floor of the canal is seen as 2 white radiopaque lines(tram lines) Narrowing of canal Diversion o f canal RADIOLOGICAL PREDICTION OF INJURY TO THE INFERIOR ALVEOLAR NERVE

16. A &B: Darkening of the root C &D: Deflection of the root E: Narrowing of root F&G: Dark& bifid apex. H&I: Interruption of white line of the canal. J,K&L: Diversion of canal. M&N: Narrowing of canal

17. Three imaginary lines which are known as George Winter’s lines can determine the position & depth of the impacted mandibular 3 rd molar. WHITE LINE- corresponsed to the occlusal plane.The line is drawn touching the occlusal sufaces of 1 st & 2 nd molar and is extended posteriorly over the 3 rd molar region.It indicates the difference in the occlusal level of 2 nd & 3 rd molars. eg : occlusal surface of the vertically impacted 3 rd molar is parallel to the white line . AMBER LINE – represents the bone level.The line is drawn from the crest of the interdental septum between the molars & extended posteriorly distal to 3 rd molar or to the ascending ramus.It denotes the alveolar bone covering the impacted tooth& portion of tooth not covered by bone . RED LINE - It is drawn perpendicular from the amber line to an Imaginary point of application of an elevator.It indicates the amount of bone that will have to be removed before elevation, i.e. the depth of the tooth in bone & the difficulty encountered in removing the tooth. - If the length of the red line is more than the 5 mm, then the Extraction is difficult. Every additional mm renders to removal of the impacted tooth 3 times more difficult WAR LINES

18. Difficulty Index A . Difficulty index for surgical extraction of impacted 3 rd molar: B.Difficulty index described by Pederson (1988): Fig: Mesioangular Class 2 level A Mandibular 3 rd molar impaction with difficulty index value 4 (slightly difficulty )

19. SURGICAL REMOVAL OF IMPACTED TEETH: Jhon Tomes in 1849, 1 st described the surgical access for removal of impacted tooth Asepsis & isolation Local anesthesia or General anesthesia Incision: Flap disgn Reflection of mucoperiosteal flap Bone removal Sectioning(division) of tooth Elevation Extraction Debridement& smoothening of bone Control of bleeding Closure – Suturing Medications Follow up

20. A. Isolation of surgical site: - Scrubbing+painting of the skin& oral mucosa. -scrubbing solution is 1 st used on skin only: Cetrimide+absolute alcohol+chlorhexidine -Cleaning solution used on skin only to remove residual soap: Normal saline, Alcohal,Spirit -Painting solution act topically ton inhibit further growth of microbes: Providone iodine 5% for skin;1% for oral mucosa. - Drape the patient with sterile drapes B.Local Anesthesia : For mandibular molar: Inferior alveolar nerve block,Long buccal nerve block & Lingual nerve block -Good infiltration is must to provide hemostasis & to define tissue plane. -Plain saline in case of hypersensitive patient -Saline adrenaline in conc. Of 1:400,000 C. Incision(Flap Design): - Well m ucoperiosteal flap design is required for adequate access,visualization of the tooth & for enough placement of retractor,drilling equipment as well as for elimination of obstruction to the pathway of removal.

21. - the incision for the mucoperiosteal flap will have an anterior limb & a post. Limb connected with/without an intermediate limb.The incision made with no. 15 blade. D.Reflection of mucoperiosteal flap for mandibular molars: Ant. Releasing incision should begin from the vestibule upwards toward midway of the CEJ of 2 nd at an angle.If deep seated 3 rd molar present,surgery requires more removal of bone,this incision should be placed ant. To the 2 nd molar. -the incision is then continued to gingival sulcus up to the distal aspect of the 3 rd molar. -Distal releasing incision is started from distal most point of 3 rd molar across external oblique ridge into the buccal mucosa. Fig A to C: Vertical periosteal flap design. Fig An envelope flap design .

22. - this incision should not be taken on the lingual aspect of the ridge ,as the lingual nerve can be found at or above the crest of the alveolar ridge. To protect lingual nerve trauma , careful elevation of a lingual flap with an appropriate sharp periosteal elevator & placement of a suitable retractor is required. The length of this flap &the no. of the teeth included will br determind by the amount of exposure necessary to gain the visibility of the region &the experience eof the clinician.

23. The incision should not be extended too far upward disatally to avoid: - Intraoprative brisk bleeding from the buccal vessels & anatomosing branches from lingual & facial arteries. -postoperative trismus due to cutting through the fibers of temoral musle . - Hernitation of buccal pad of fat into the surgical field. - The sharp point of periosteal elevator is used to elevate,a mucoperiosteal flap carefully beginning at the point of the incision behind the 2 nd molar. - The elevator is brought forward to elevate periosteum around the 2 nd molar &down the releasing incision The other flatter end of the periosteal elevator used to elevate periosteum posteriorly to the ascending ramus of the mandible. A Minnesota retractor is placed just lateral to the external oblique ridge and stabilized against the lateral surface of the mandible.

24. BONE REMOVAL AIM: -To expose/uncover the crown by removing the bone overlying it. -To remove the bone obstructing the pathway for removal of a tooth. 2 ways of Bone removal : 1. High speed,high torque handpiece&bur technique 2.Chisel & mallet technique. 1.Bur technique: Either no. 7/8 round bur or a straight no. 702 or 703 carbide bus is used. Bur should be used along with copious saline irrigation to avoid thermal trauma to the bone. 1 st step: the bur is used in a sweeping motion around the occlusal , buccal & distal aspect of mandibular 3 rd molar crown to expose it. 2 nd Step: ( Moore Gillbe Collar technique ); once the tooth crown is located ,the buccal suface of the tooth is exposed with the bur to the cervical level of the crown contour & a buccal trough or gutter/ collar (made in cancellous bone)is created.

25. - It is important that the adequate amount of trough is created to remove any bony obstruction for exposure& the delivery of the tooth,especially aound the distal aspect of the crown. 2. Chisel& mallet technique: Less bone necrosis than bur technique Can cause inadvertent fracture of the bone The jaw bone is supported in this technique. First step: the placement of vertical stop cut,which made by placing a 3mm/5mm chisel vertically at the distal aspect of the 2 nd molar with bevel facing posteriorly (5-6mm height).

26. Second step: At the base of the vertical stop(limiting) cut,the chiselm is placed at angle of 45º with bevel facing upwards or occlusally & oblique cut is made till the distal most point of 3 rd molar. Removal of triangular piece of buccal plate distal to 2 nd molar Gain entry of the elevator tip

27. LINGUAL BONE SPLIT TECHNIQUE Described by Sir William Kelsey FRY. STEPS: - vertical stop cut is made by placing the chisel,distal to the 2 nd molar with chisel bevel downward, a horizontal stop cut is made backward the lower end of the vertical stop cut buccal bone plate is removed distolingual bone is fractured inward by cutting edge held at 45º to the bone surface remaining bone between the buccal & lingual cut is removed elevate the tooth by a sharp straight elevator tooth moves upward & backward,then lingual plate gets fractured and facillated the delivery of the tooth tooth is removed lingual plate is grasped with the hemostat & freed from the soft tissue and removed smoothening of the edges is done with bone file. Wound irrigated & sutured.

28. A . soft tissue reflection by a standard incision B. vertical stop cut is made by chisel at anterior end of the wound C. horizontal stop cut is made backwards from a point just above the lower end of vertical cut. D.Excision of triangular piece of bone bounded ant. By the lower end of stop cut. c . the distolingual bone fracture. d. Separation of lingual plate from rest of the alveolar bone. E.The peninsula of bone,between thwe lingual & buccal cut is excised. F.displacement of tooth G.lingual plates are grasped in the fine haemostat & soft tissues are freed from it. H. smoothening of the bone by bone file

29. TOOTH/ROOT SECTIONING:ODONTECTOMY Reduce amount of bone removal Reduce the risk of damage to the adjacent teeth Avoids inadvertent jaw fracture Reduces total surgery time Planned sectioning permits the parts of the tooth to be remove separately in an atrumatic manner by creating a space into which it is displaced & the remaining crown or root segments. The direction of the root sectioning is dependent on angulation of the impacted tooth. Can be performed either with a bur or chisel.Bur use is preferable. The tooth is usually sectioned one-half to ¾ with the bur & then is is completely sectioned with the elevator. INDICATIONS: - deep impacted tooth,with lot of bone coverage -large bulbous crown,locked under 2 nd molar -unfavourable root anatomy

30. - roots with close proximity to IAN - extencively carious tooth Bulbous root Narrow periodontal ligament space 1.IN CASE OF VERTICAL AND MESIOANGULAR IMPACTION : PROCEDURE: distal half of the crown is sectioned off from the buccal groove, till the CEJ ; extended into the furcation → straight elevator is placed in to the cut & rotate to fracture the distal part of the crown which is removed → Straight elevator placed into the mesial aspect of 3 rd molar below the cervical area→ elevate the tooth by a crane / cryer elevator , engaging the purchase point.

31. 2. IN CASE OF HORIZONTAL IMPACTION & DISTOANGULAR IMPACTION: Most difficult to remove Large amount of distal bone removal is required. PROCEDURE: -the crown is sectioned from the roots just avove the cervical line after sufficient bone removal from occlusal & distobuccal aspect -entire crown is removed to improved the visibility and access the root. -if roots are divergent, they are further sectioned into 2 pieces and delivered individually.

32. Coupland elevator: placed at the base of the crown Winter Cryer’s : may be used in buccal elevation/wedging action. PRECAUTIONS: - Support the inferior border and lingual cortex of the bone in mandibular impaction. DEBRIDEMENT, DECONTAMINATION & SMOOTHENING OF BONE MARGINS: Irrigation of the socket Curreting to remove any remaining dental follicle and epithelium Look for pieces of coronal portion ( espceally for carious teeth), chek for remnant of the bone /granulation tissue , bleedind point Inspection for fracture of lingual plate Round off margins of the socket with bone file / large vulcanite round bar. Irrigated the socket again & inspect again Control the bleeding before suturing ELEVATION :

33. CLOSURE WITH PROPER APPROXIMATION A 3-0 black silk is used . Interrupted sutures given & maintained for 7 days. 21mim or 23mm half circle or 1.25 mm 5/8 circle cutting needle is used. In case of molars, suture distal to 2 nd molar should be placed first & should be water tight to prevent pocket formation. Use as few suture as possible .

34. OPG showing horizontally impacted lower right and left 3 rd molar Intraoral clinical picture Incision and mucoperiosteal flap reflection Sectioning of a tooth Surgical extraction done Suturing Extracted tooth

35. EARLY REMOVAL OR GERMECTOMY Described by Bowdler Henry Removal of unerupted wishdom tooth, with less than 1/3 root formation(9 to 16 years age) Advocated when prediction of interference with the proper development of the 2 nd molar is made. LATERAL TREPHINATION TECHNIQUE : A modified S- shaped incision is used from retromolar fossa, across external oblique ridge to the 1 st molar. Mucoperosteal flap reflection Round bur is used to trephine the crypt of the 3 rd molar,

36. An extended s shaped incision is made from the retromolar fossa,across the external oblique ridge,curving down through the attached mucoperiosteum along the mucous membrane to the ant. Border of the permanent 1 st molar. Soft tissue elevation by Bowdler Henry retractor. A second cut through the outer plate is made at the posterior end of the crypt at an angle 45º from the row of trephine holes. Out fracture of buccal plate by chisel in vertical direction, exposing the crown of the 3 rd molar by curved haemostat. A warwick James elevator is applied to the occlusal suface of the tooth to deliver it. Suturing.

37. COMPLICATIONS INTRA-OPERATIVE COMPLICATION: DURING INCISION: -For molars,facial vessels or buccal vessles may be cut. -Injury to lingual nerve ,if not careful. During Bone Removal- 1.Damage to the second molar. 2.Damage to the roots of overlying teeth. 3.Slipping of bur into the soft tissues. 4.Breakage of bur and getting embedded in the bone. 5.Fracture of the mandible when using chisel and malate .

38. During Elevation- Luxation of neighbouring or overlying tooth. Fracture of the adjoining bone. Fracture of the tuberosity. Fracture of mandible. Soft-tissue injury. Damage to nasal wall/ overlying teeth/ Lingual, Inferior alveolar or mental nerve. Slipping of the tooth into pterygomandibular , sub-lingual pouch. Breakage of elevator tip. Temperomandibular joint dislocation. During Debridement: Damage to inferior alveolar nerve and lingual nerve .

39. Post Operative Complications Pain due to dry socket. Swelling due to oedema, hematoma formation. Trismus . Hemorrhage . Loss of vitality of neighbouring teeth. Pocket formation. Sinus tract formation.

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