Impaction of mandibular 3rd molar

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1. Impaction of 3 rd molars By , Aswanth.E.P

2. Contents Definition Etiology Indications Cntraindications Classifications Clinical examination Radiographical analysis Preoperative evaluation of difficulty of removal of impacted teeth Other methodrs Conclusion Reference

3. Introduction Tooth can be impacted due to various reasons 3 rd molar is commonly imapacted in adults Proper diagnosis is important in management of impacted teeth. There are many surgical techniques available to manage impacted tooth .

4. Definition ‘ A tooth which is completely or partially unerupted and is positioned against another tooth, bone or soft tissue,so that its further eruption is unlikely,described according to its anatomic position ’ -Archer

5. Etiology of impaction a) local causes of impaction Irregularity in the position and pressure of an adjacent tooth. 2 . The density of the overlying or surrounding bone. 3 . Long continued chronic inflammation with resultant increase in density of the overlying mucous membrane. 4 . Lack of space due to under developed jaws. 5 . Unduly long retention of the primary tooth. 6 . Premature loss of primary tooth. 7 . Acquired diseases such as necrosis due to infection or abscess

6. b) systemic causes of impaction : 1)Prenatal causes: Hereditary 2)Post natal causes: Rickets, anemia , congenital syphilis 3)Rare conditions: Cleidocranial dysostosis , cleft palate .

7. Theories of impaction 1.Discrepancy between the arch length and the tooth size. 2 . Differential growth of the mesial and distal roots. 3 . Retarded maturation of the third molar—dental development of the tooth lags behind the skeletal growth and maturation. 4 . Incidence of extraction of permanent molars is reduced in the mixed dentition period, thus providing less room for eruption of third molars. This is very relevant in the present day due to increased awareness of the population and dental treatment started early in childhood. 5 . Evolution theory. 6 . Lack of development of jaw bones due to consumption of more refined food which causes lack of functional stimulation to the growth of jaw bone.

8. indications for removal of impacted tooth 1) Pericoronitis and Pericoronal abscess 2) Dental Caries –to preserve other molars from caries 3) Periodontal diseases 4) Orthodontic reasons: a) Crowding of incisors b) To facilitate orthodontic treatment 5) To facilitate orthognathic surgery 6) Odontogenic cysts and tumors

9. Contraindications 1)Extreme of age 2) Compramised medical status 3)Probable excessive damage to adjacent structures 4)Recently irradiated jaw 5)Tooth in tumour Absolute contraindications: 1)Acute pericoronitis 2)Acute necrotizing ulcerative gingivitis 3)Haemophilia 4)Thyrotoxicosis

10. Classifications According to angulation of the impacted tooth by winter a) Mesioangular b) Distoangular c)Vertical d)Horizontal e) Buccoangular f) Linguoangular g)Inverted

11. 2)According to relationship of the impacted tooth to the anterior border of the ramus (Pell and Gregory Classification ) Class I: Sufficient space available anterior to the anterior border of ramus for the third molar to erupt. Class II: Space available is less than the mesio distal width of the crown of the third molar Class III: All or most of the third molar is located within the ramus.

12. 3) Acording to relationship to occlusal plane (Pell and Gregory Classification) Position A: The highest portion of the tooth (occlusal plane) is on a level with or above the occlusal line . Position B: The highest portion of the tooth is below the occlusal line but above the cervical line of second molar . Position C: The highest portion of the tooth is below the cervical line of second molar.

13. Pell and Gregory Classification - summery

14. 4)According to type of tissue overlying the tooth soft tissue partial bony complete bony impaction 5)According to state of eruption a)Erupted b)Partially erupted c) Unerupted

15. WHARFE assessment To asses the difficulty of impaction procedure 6 Factors involved are : 1)Winters classification 2)Height of mandible 3)Angulation of 2 nd molar 4)Root shape and morphology 5)Follicle development 6)Path of exit of tooth during removal

16. Total score - 33

17. Clinical Examination This include : History taking ( 2) Extra oral examination (3 ) Intraoral examination 1)History taking : Complaints of the patient Medical and dental history Significance of Medical Evaluation Additional investigations: Clotting time for those with history of bleeding . Alteration of patient's current medication to facilitate surgery : Stopping warfarin preoperatively Selection of medication : Avoid penicillin in those who reported with history of allergy to it..

18. 2) Extraoral Examination Face and neck is examined for signs of swelling or redness of the cheek suggestive of infection. Regional lymph nodes are palpated for enlargement and tenderness. 3)Intraoral Examination Mouth opening - In retrognathic mandible accessibility to third molar area is restricted, while in prognathic mandible accessibility is better General examination of oral cavity & 3 rd molar area - Oral mucosa, teeth, oral hygiene. Condition of impacted tooth - Carious or with fillings, internal resorption, angulation of tooth, locking of crown of third molar beneath second molar. Amount of space available between the distal surface of second molar and the ascending ramus Fracture may complicate the removal of an impacted third molar.

19. Radiography of Impacted Third Molar 1)Periapical radiograph

20. 2)Occlusal x-ray Helps in viewing buccal / lingual version of impacted tooth 3)Lateral oblique view of mandible : To provide additional information like vertical height of mandible in the area, amount of bone beneath deeply buried impacted tooth

21. 4) Orthopantomogram OPG is considered the gold standard for surveying the maxilla and mandible for diseases and other pathological conditions in the lateral plane.

22. Interpretation of Periapical X-ray Access b.Position and depth of impacted tooth c.Root pattern of impacted tooth d.Shape of crown e.Texture of investing bone f . Relation to inferior alveolar canal g.Position and root pattern of second molar. Factors include :

23. a)Access : By noting the inclination of the radioopaque line cast by the external oblique ridge the ease of access can be determined. If this line is vertical the access is poor and if horizontal, access is good.

24. b)Position of impacted tooth : determined by a method described by George Winter three imaginary lines are drawn on the radiograph , described as WAR li nes / Winter’s lines which include W hite line A mber line R ed line 1)White line : Drawn along the occlusal surface of the erupted mandibular molars and extended posteriorly over the third molar region. From this the axial inclination or position of impacted tooth can be assessed Eg : parallel to the occlusal surface of a vertically impacted tooth

25. 2)Amber line Drawn from the surface of the bone lying distal to the third molar to the crest of the interdental septum between the first and second molar. Indicates the margin of the alveolar bone enclosing the tooth . 3)Red line It is a perpendicular dropped from the 'amber' line to an imaginary 'point of application' of an elevator With the exception of disto -angular impaction, the CEJ on the mesial surface of the impacted tooth is used for this purpose(in disto angular, cemento -enamel junction on the distal side of the impacted tooth used to draw red line) Used to measure the depth at which the impacted tooth lies within the mandible

26. c)Root pattern of impacted tooth Number , shape and curvature of roots are noted. Limited root development leads to a "rolling" tooth, which can be difficult to remove. Roots with severe curvature, however, are more difficult to remove than less curved or straight roots

27. d)Shape of crown Teeth with large square crowns and prominent cusps are more difficult to remove than teeth with small crowns and flat cusps. size and shape of the crown of third molar acquire importance when the 'line of withdrawal' of the tooth is obstructed by the crown of the second molar, a condition referred to as ' tooth impaction' or 'locking of the crown' e)Texture of the investing bone more dense the bone, the less the degree of bony expansion during luxation and more time required for its removal with a bur f)Inferior alveolar canal: This structure is frequently seen to be crossing the roots of the third molar

28. g)Position , root pattern and nature of crown of second molar: closer the third molar is to the second molar, the more difficult the surgery becomes CT evaluation OPG has following disadvantages : Does not provide a coronal view of the third molar area. Does not show the relationship of the root apices to the inferior alveolar canal in all planes of space. Does not provide predictable evidence of bone density Ct provides all these informations .

29. Pederson Scale for preoperative evaluation of difficulty of removal of teeth:

30. Surgical management of impacted 3 rd molar wipe the patient's face with an antiseptic solution like povidoneiodine (Betadine), followed by the administration of local anesthetic injection . 1. Incision and Designing the Flap F irst step in removing the impacted tooth is to reflect a mucoperiosteal flap F lap should be of adequate size to permit access, allow adequate visibility and to ensure unhindered healing without periodontal pocket formation distal to second molar

31. most commonly used flap is the envelope flap which extends from just posterior to the position of the impacted tooth anteriorly to the level of the first molar. Posterior end of the incision is directed buccally along the external oblique ridge . If more access needed , triangular flap used. This incision is started from a point approximately 6 mm down in the buccal sulcus and then extended obliquely upwards to the gingival margin to a point at the junction of the posterior and middle thirds of the second molar

32. Ward incision Incision begins 6.4mm in buccal sulcus at the junction of middile & posterior third of 2 nd molar Passed upward to distobuccal angle of 2 nd molar. Cervically behind the tooth to midline of its posterior surface. Taken back & laterally to prevent vesselinjury to retromolar area. In final continuation,it penetrates mucosa of cheek. Modified ward incision Anterior incision is commensed at the distobuccal corner of crown of mandibular 1 st molar instead of 2 nd molar.

33. 2. Bone Removal Amount of bone removal varies with the depth of impaction . Accomplished either by use of bur, or chisel and mallet or a combination of the two methods To free the tooth from obstruction and to provide a point of application for the elevator . most common technique using a chisel is the 'lingual split bone technique' introduced by Ward , in which section of bone lingual to the wisdom tooth is fractured off to facilitate the removal of the impacted tooth . buccal bone removal should be kept to minimum to avoid weakening of the mandible and subsequent fracture . bone on the buccal and the distal aspect of the impacted tooth is removed down to the level of the cervical line. Further if need, drilling a deep vertical gutter alongside the buccal aspect and if required on the distal aspect of the tooth. This 'guttering method ' will ensure that the height of the buccal plate is maintained without weakening the mandible

34. Elevation of tooth from the socket E xcessive force can result in unfavourable root fracture, buccal or lingual bone loss, damage to the adjacent second molar or even fracture of mandible. Thus, Elevators with less mechanical efficiency like Warwick James elevator (straight and curved type) and Coupland chisels are recommended 3. Sectioning and Tooth Deliver For easy delivery from the socket Sectioning of tooth reduces operating time and also avoids the need to remove additional amount of bone to accommodate the elevated tooth. Performed either with a bur or a chisel In the standard technique, first section is generally done at the neck of the tooth using bur. This will facilitate the removal of the crown followed by the roots in one piece

35. 4. Debridement D ebriding the wound of all particular bone chips and other debris Debriding the socket and the area under the flap with a periapical cruet A bone file is used to smooth any rough and sharp edges of the bone socket and the wound margins (including under surface of mucoperiosteum ) is irrigated with saline to remove bone and tooth debris. 5. Wound Closure Bleeding from the socket is completely arrested before attempting closure Flap is then returned to its original position and the initial suture placed just distal to the second molar The needle is passed from the buccal to the lingual side . S utures should be just tight enough to hold the flap patient is then asked to bite firmly on a gauze piece for 30 mts. to one hour or till the bleeding stops.

36. Other methods : 1) Sagital split ramus osteotomy : U sed for the surgical correction of mandibular excess (push back) and for mandibular deficiency (advancement). Provide good access, conserves bone that would otherwise have been removed, and allows the nerve to be seen and avoided.

37. 2)Buccal Corticotomy A trapezoidal mucoperiosteal flap is raised in the mandibular molar region. R ectangular window is made over the deeply impacted tooth using a narrow fissure bur, with the mesial and distal cuts almost reaching the inferior border of the mandible Buccal corticotomy window is removed with an osteotome . The deeply impacted molar is exposed, divided with a bur and removed.

38. Conclusion Impaction of 3 rd molar have different etiologies . Dental caries,pericoronitis … are indications for management of impacted tooth In aged patients,it is contraindicated. Impaction can classify based on angulation,position … History,intraoral and extraoral examinations used in diagnosis Radiographs are also beneficial. There are many surgical techniques available for management of impacted tooth.

39. Reference 1)A practical guide to management of impacted tooth By K George Varghese 2)Textbook of oral & maxillofacial surgery by S M balaji