MANDIBULAR 3RD MOLAR IMPACTION

ORAL & MAXILLOFACIAL SURGERY

1. PRESENTED BY – Dr.ANKITA RAJ (MDS Reader) Oral & Maxillofacial Surgery Department Rama Dental College, Kanpur

2. EXODONTIA AND MANDIBULAR 3 RD MOLAR IMPACTION

3. DEFINITION Impacted tooth is a tooth that is partially or completely unerupted and is positioned against another tooth or bone or soft tissue so that its further eruption is unlikely beyond the normal chronological age. ~ARCHER 1975

4. FREQUENCY OF IMPACTED TEETH OCCURS IN THE FOLLOWING ORDER : Mandibular third molars Maxillary third molars Maxillary cuspids Mandibular bicuspids Mandibular cuspids Maxillary bicuspids Maxillary central incisors Maxillary lateral incisors

5. THEORIE S OF IMPACTION Orthodontic theory (small jaw-decreased space): Growth of the jaw and movement of teeth occurs in forward direction, anything that interferes with such moment will cause an impaction (small jaw-decreased space). A dense bone decreases the movement of the teeth: acute infection Local inflammation of PDL Malocclusion, Trauma Early loss of primary teeth and arrested growth of the jaw

6. Nodine’s Phylogenic theory : Nature tries to eliminate the disused organs. This causes elimination of the unused teeth which causes congenital absence of third molars . Mendelian theory: Heredity is the most common cause. An individual may inherit small jaws from one parent and a complement of large teeth from the other, i.e. hereditary transmission of small jaws and large teeth from parents to children.

7. Pathological theory: Osteosclerosis in the third molar area, caused by the early disease of adjacent molars, cause chronic infections affecting an individual and may bring the condensation of osseous tissue further preventing the growth and development of the jaws. Endocrinal theory: Increase or decrease in the growth hormone secretion may affect the size of the jaws. Nature and nurture theory: A. J. MacGregor explains that impaction can occur due to a mismatch in size and shape of teeth and jaws.

8. ETIOLOGY Local causes Irregularity in the position and pressure of the adjacent tooth. Density of the overlying or surrounding bone. Localised chronic inflammation Lack of space due to underdeveloped jaws. Obstructions (soft or hard tissue ) Dilaceration Over retained deciduous teeth. Ectopic position of tooth bud.

9. Systemic causes Prenatal causes: Heredity Postnatal causes: Rickets Anaemia Congenital syphilis Tuberculosis Endocrine dysfunctions Malnutrition C. Rare conditions: Cleidocranial dysostosis Oxycephaly Progeria Osteopetrosis Cleft palate

10. RATIONALE FOR REMOVING IMPACTED TOOTH Indications: Preventing and treating Pericoronitis . Recurrent Pericoronitis For prevention of dental caries. Orthodontic considerations. To prevent pathosis . Prevention of root resorption . Impacted teeth and dental prosthesis. Prevention of dental diseases.

11. CONTRAINDICATIONS: Extremes of age. Medically compromised patient. Probable excessive damage to the adjacent structures. Prevention of fracture of jaws. Prevention of pain of unexplained origin.

12. CLASSIFICATION Based on the nature of the overlying tissue Winter’s classification Pell and Gregory’s classification Killey & Key’s classification

13. A. BASED ON THE NATURE OF THE OVERLYING TISSUE Soft tissue impaction Hard tissue impaction

14. B . WINTER’S CLASSIFICATION I. Mesioangular : Long axis of 3rd molar bisects the long axis 2nd molar at or above occlusal plane Mesioangular 38—(A) long axis of 38 bisects the long axis 37 above the occlusal plane. (B) Interradicular bone width between 37 and 38 is more than interradicular bone width between 36 and 37.

15. II. Distoangular : Long axis of 3rd molar away from long axis of 2nd molar at the level of occlusal plane Distoangular—(A) long axis of 48 is away from long axis of 47 at the level of occlusal plane. (B) The interradicular bone between 47 and 48 is almost obliterated and less than that between 46 and 47.

16. III. Horizontal: Long axis of 3rd molar bisect long axis of 2nd molar at right angle. Horizontal—long axis of 38 bisects long axis of 37 at right angle.

17. IV. Vertical : The long axis of the impacted tooth runs parallel to the long axis of the second molar Vertical—the long axis of the impacted 48 runs parallel to the long axis of the 47. Vertical—interradicular bone width between 47 and 48 equal to interradicular bone width between 46 and 47.

18. WINTERS CLASSIFICATION Buccoangular

19. C. PELL AND GREGORY’S CLASSIFICATION I. Based on their relationship with the anterior border of the mandible : Class I: The anteroposterior diameter of the tooth is equal to the space between the anterior border of ramus of the mandible and distal surface of the second molar tooth Class II: A small amount of bone covers the distal surface of the tooth and The space is inadequate for eruption of the tooth, i.e. mesiodistal diameter of the tooth is greater than the space available. Class III: Tooth is located completely within the ramus of the mandible– least accessible.

20. II. Based upon the amount of bone covering the impacted tooth and relation to occlusal plane Position A: Occlusal plane of the impacted tooth is nearly in the same level as the occlusal level of the adjacent second molar tooth occlusal level of 47. Position B: Occlusal plane of the impacted tooth is in the midway between the cervical line and the occlusal plane of the adjacent second molar tooth. Position C: Occlusal plane of the impacted tooth below the level of cervical line of the second tooth. This can be applied for the maxillary teeth also.

21. III. Based on long axis of the impacted tooth : It is similar to the one as proposed in the Winter’s classification

22. D) Killey & Key’s classification Based on angulation and position: Same as George Winters. b) Based on the state of eruption: - Completely erupted - Partially erupted - Unerupted c) Based on pattern of roots: 1) - Fused roots. - Two roots. - Two roots and multiple roots 2) Root pattern may be – - Surgical favourable - Surgical unfavourable

23. CLINICAL EVALUATION

24. LOCAL EXAMINATION Occlusal relationship Presence of local infection Periodontal status Resorption of the second molars External oblique ridge Internal oblique ridge Upper third molar Soft tissue assessment Regional lymph nodes

25. RADIOLOGICAL ASSESSMENT Types of radiographs used Intraoral periapical (IOPA) radiograph Bitewing radiograph Occlusal radiograph Lateral oblique radiograph Orthopantomograph (OPG) CBCT (in indicated cases)

26. INTERPRETATION OF THE RADIOGRAPH WAR lines White line White line is drawn along the occlusal surfaces of the erupted mandibular molars and extended over the third molar region posteriorly. Indicates The depth of the tooth within the mandible. Relationship of occlusal surface of impacted tooth with the erupted molars.

27. Amber line Amber line is drawn from the surface of the bone on the distal aspect of the third molar to the crest of the interdental septum between the first and second mandibular molars. This line represents the margin of the alveolar bone covering the third molar.

28. Red line It is the perpendicular line drawn from the amber line to the imaginary point of application for the elevator (all types-mesial, distoangular-distal) The length of the red line indicates depth of the impacted tooth. With each increase in length of the red line by 1 mm, the impacted tooth becomes three times more difficult to remove.

29. ASSESSMENT OF DIFFICULTY OF REMOVAL

30. A) Spatial Relationship Value - Mesioangular 1 - Horizontal / transverse 2 - Vertical 3 - Distoangular 4 B) Depth   - Level A 1 - Level B 2 - Level C 3 C) Ramus relationship   - Class I 1 - Class II 2 - Class III 3 PE D ERSON DIFFICULTY INDEX Classification: Difficulty scores: Very difficult 7-10 Moderately 5-7 Minimally 3-4 Example: Mesioangular tooth 1 difficulty score is Level B 2 5-7 Class III 3 Moderately difficult

31. Relationship of 3 rd molar to the INFERIOR DENTAL CANAL . Darkening of roots Deflection of roots Narrowing of roots Dark & Bifid apex Interruption of white line of canal Diversion of canal Narrowing of canal

32. SURGICAL REMOVAL OF IMPACTED THIRD MOLAR

33. 34 BASIC INSTRUMENTS C heek retraction and visualization - M outh mirror, prop, of the surgical area cheek retractor I ncision - BP Handle & No. 15 blade Flap development & reflection - Moon’s probe, Howarth’s periosteal elevator Flap retraction - Austin’s retractor Bone removal - Handpiece , bur, chisel L uxation - E levators T ooth removal - F orceps Suturing - Sutures & needle holder

34. 35

35. STEPS IN REMOVAL OF IMPACTED TEETH Isolation Anaesthesia Incision and flap design (flap elevation and retraction) Bone removal Sectioning/division of tooth (if required) Elevation and extraction of tooth Debridement and smoothening of bone Control of bleeding Flap repositioning and Suturing Follow up 36

36. Step 4 : Incisions placed

37. Step 5 : Buccal Mucoperiosteal flap raised Step 6 : Lingual Mucoperiosteal flap raised and complete exposure of the tooth done.

38. Step 7 : Guttering of the mesial and distal bone. Step 8 : Odontectomy performed.

39. Step 10: Removal of mesial segment Step 9 : Removal of distal segment

40. Step 11 : Extraoral reorientation of the extraoral fragments. Step 12 : Wound debridement and primary closure.

41. OTHER TECHNIQUES A. LATERAL TREPHINATION TECHNIQUE The external oblique ridge is palpated and an S-shaped incision is made. Incision line starts from the retromolar fossa and extends across the external oblique ridge curving down along the reflection of the mucous membrane above the vestibule and ends anterior to the first permanent molar.

42. Using a round bur, the buccal cortical plate over the third molar crypt is trephined and is fractured to expose the third molar crypt using a chisel Using an elevator, the impacted tooth is delivered out of the crypt.

43. B. LINGUAL SPLIT TECHNIQUE (Kelsey fry technique) Takes advantage of the thinness of the lingual cortical plate, avoids and preserves plate and hence preserves the buccal plate and external oblique ridge.

44. ENVELOP FLAP

45. Surgical Step Complication Incision Hemorrhage Lingual nerve damage Bone removal Injury to soft tissues Damage to 2nd molar Splitting of ramus Damage to bone Elevation of Tooth Fracture of tooth Damage to 2nd molar Damage to I.D bundle Fracture of mandible Slipping of the tooth Preparation of the wound Damage to I.D. nerve and vessels Complications During Surgical Procedure 50

46. Dry socket Pain Swelling Trismus Paraesthesia Sensitivity Loss of vitality Pocket formation 51 Complications After Surgical Procedure

47. Thank you for listening