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![Theories of impaction
2) 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.
8](https://image.slidesharecdn.com/thirdmolarimpaction-240707142040-d7c205c8/75/THIRD-MOLAR-IMPACTed-tooth-development-Surgical-complications-pptx-8-2048.jpg)
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THIRD MOLAR IMPACTed tooth , development & Surgical complications.pptx
- 1. PRESENTED BY: Dr. ArindomChangmai Sr. Lecturer,DEPT. OF OMFS GOVERNMENT DENTAL COLLEGE, SILCHAR ,ASSAM 1
- 2. CONTENTS INTRODUCTION DEFINITIONS THEORIES OF IMPACTION ETIOLOGY INDICATION AND CONTRAINDICATION CLASSIFICATION SURGICAL ANATOMY RADIOLOGICAL ASSESSMENT ASSESSMENT OF SURGICAL DIFFICULTY SURGICAL PROCEDURE COMPLICATIONS RECENT ADVANCES REFERENCES 2
- 3. INTRODUCTION The thirdmolar 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) Also because of its late eruption it is the most commonly impacted tooth. The word impaction is derived from the latin word impactus. The surgical removal of 3rd molars has been and still is the most common operation performed by the oral and maxillofacial surgeon both in clinical practice as well as in a hospital setting. 3
- 4. Mandibular Third Molar Calcificationand Eruption Calcification begins……………….9 years Crown completed………………….14 years Eruption……………………………….19 years Root completed…………………….21.5 years 4
- 5. DEFINITIONS According toWHO – An impacted tooth is any tooth that is prevented from reaching its normal position in the mouth by tissue, bone or another tooth. According to Archer- 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 . According to Anderson-An impacted tooth is a tooth -which is prevented from completely erupting into a normal functional position due to lack of space, obstruction by another tooth or an abnormal eruption path 5
- 6. WHEN IS ATOOTH CONSIDERED IMPACTED? A tooth is considered impacted if : It has failed to erupt fully within the expected time of eruption If the angulation of the tooth is such that its eruption into the oral cavity is unlikely When the ratio of crown to the space available for eruption is lesser than 1 6
- 7. THEORIES OF IMPACTION(DURBECK) 1)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. 7
- 8. Theories of impaction 2)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. 8
- 9. Theories of impaction 3)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 jaws 9
- 10. ETIOLOGY OF IMPACTION (BERGER) LOCAL CAUSES Lack of Space in the Dental arch Obstruction for eruption Ankylosis Retained deciduous teeth Non absorbing alveolar bone Bony lesion Ectopic position of tooth bud Habits involving tongue, finger,cheek,pencil,etc. 10
- 11. SYSTEMIC CAUSES Prenatal causes Heredity Postnatal causes Rickets Anemia Congenital syphilis T.B Endocrine dysfunctions Malnutrition Rare conditions Cleidocranial dysostosis Oxycephaly Progeria Achondroplasia Cleft palate 11
- 12. Indications for removal “Astrong 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. Infection Caries Orthodontic consideration Prosthetic consideration Other pathology 12
- 13.
- 14. CONTRAINDICATIONS OF THIRDMOLAR REMOVAL Extremes of Age Compromised Medical Status Surgical Damage to Adjacent Structures 14
- 15.
- 16. According to Supero-InferiorPosition of 3rd Molar Crown to crown Crown to cervix Crown to root 16
- 17. 17 Killey & Kay’sClassification a) Based on angulation and position: (Same as Winter’s 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 unfavorable
- 18.
- 19. The AAOMS publishedthe ADA coding with explanations from the AAOMS procedural terminology, in parentheses, as follows: 07220 : (overlying) soft tissue impaction. 07230 : partially bony Impaction 07240 : complete bony impaction 07241 : complete bony impaction, with unusual surgical complications. 19
- 20. G.R.OGDEN METHOD A simplemethod of determining the type of impaction involves comparing the distance between the roots of 3rd and 2nd molars , with the distance between the roots of the 2nd and 1st molars . 20
- 21.
- 22. Surgical Anatomy Location: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. Retro Molar triangle- depressed roughened area post. to 3rd molar 22
- 23. 23 Muscles: Vestibule isformed by the attachment of buccinator buccally and mylohyoid lingually. Along the anterior border of the ramus - is tendinous insertion of temporalis. Excessive stripping of these muscle will cause hematoma, pain and trismus.
- 24. The Retromolar Triangle Behind the third molar is a depressed roughened area on the upper surface of the mandible which is bounded by the lingual and buccal crests of the alveolar ridge this is the retromolar triangle. Lying lateral to the retromolar triangle is a shallow, hollow depression, the retromolar fossa, which is bounded by the anterior border of the ascending ramus. This is the area into which a third molar would erupt if the usual dental arch were shrunk by abrasive and attritive foods. Spread of acute inflammatory processes may occur in any transverse plane from the retromolar triangle. The retromolar triangle is the site for initial surgical procedures to remove the usual impacted mandibular third molars. 24
- 25. Facial artery andveins The facial artery crosses the region of 1st mandibular molar at the anterior border of the massetor This artery can be severed accidentally during surgical procedure Hence deep incisions in 1st molar area predispose a risk of injuring facial artery 25
- 26. INFERIOR ALVEOLAR NERVECANAL The mandibular canal is located inside the jaw and transmits the lower alveolar artery and lower alveolar nerve, a branch of the third division of the trigeminal nerve, from the mandibular foramen to the mental foramen (BERBERI et al., 1994 and MADEIRA, 1995). The radiographic appearance of the mandibular canal is characterized by a radiolucent line delimited by two radiopaque lines (WORTH, 1975) . 26
- 27.
- 28. LINGUAL NERVE TheLN, a branch of the mandibular division of the trigeminal nerve provides sensory innervation to the ipsilateral two- thirds of the mucous membranes of the tongue, floor of mouth and the mandibular lingual gingiva (Liegbott, 1986; Zur et al., 2004). The origin of the LN begins as a branch from the posterior division of trigeminal nerve in the infratemporal fossa. While in the infratemporal fossa, the chorda tympani joins the LN at an acute angle as it exits through the pterygotympanic fissure of the glenoid fossa (Girod et al., 1989). 28
- 29. The LNcourses from a more lateral to medial position as it approaches the mandibular third molar due to the oblique flare in the mandible in this region. 29
- 30. Pre operative assessment Clinicalassessment; History Age Mouth opening Size of mouth and tongue Flexibility of the oral musculature Physical status of the patient Palpation of external oblique ridge Existing pathology 30
- 31. RADIOLOGICAL ASSESSMENT Thepurpose of a careful radiological evaluation is to complement the clinical examination by providing additional information about the third molar, the related teeth and anatomical features, and the surrounding bone. 31
- 32. RADIOGRAPHIC ASSESSMENT Assessmentof angulations and depth Number and shape of roots Relation of the third molar roots to the mandibular canal Condition of the second molar Density of the bone Bone loss Follicular size Existing pathology 32
- 33. All radiographs shouldbe of a diagnostically acceptable standard. 33
- 34.
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- 40.
- 41. ASSESSMENT OF SURGICALDIFFICULTY Although the extraction of impacted lower third molars is common in oral surgical practice, it may be difficult. Various methods have been proposed for the preoperative evaluation of difficulty, but these have often been of limited validity. Few authors have proposed indexes for measuring intraoperative/surgical difficulty. Pederson proposed such an index, but it is seldom used because it has been reported that it does not match actual surgical difficulty. 41
- 42.
- 43. DRAWBACKS OF PEDERSONSCALE The Sensitivity of the Pederson Index in identifying very difficult cases was 20%. No clinical variables are included. Root morphology is not included. 43
- 44.
- 45. WHARFE ASSESSMENT BYMcGREGOR(1985) The six factors chosen for scoring are: Winters classification Height of the mandible Angulation of the 2nd molar Root shape & morphology Follicle development Path of Exit of the tooth during removal 45
- 46.
- 47.
- 48. Factors That Make Impaction Surgery…Less Difficult 48
- 49.
- 50. SURGICAL PROCEDURE FIVEBASIC STEPS: ADEQUATE EXPOSURE ACCESS TO THE TOOTH SECTIONING OF THE TOOTH(OPTIONAL) ELEVATION FROM THE ALVEOLAR PROCESS DEBRIDMENT & IRRIGATION 50
- 51.
- 52. Wards incision 52 Sir TGWard 1968, made some modification of the incision. The anterior line of the incision runs from the distal aspect of the second molar curving ,downward and forward to the level of the apex of the distal root of the first molar. The posterior part of the incision is the same but the anterior part commences as the junction of the anterior and middle thirds of the second molar and runs down to the apex of the distal root of the first molar.
- 53. CHISEL AND MALLET Traditional technique, Support of mandible is mandatory The chisel is kept parallel to the long axis of bone Indications 53 Young patients An external oblique ridge slightly below the level of bone enclosing the 3rd molar An external oblique ridge that is slightly behind the 3rd molar so that the distolingual corner of the tooth sits in a thin balcony of bone
- 54.
- 55. LOW SPEED ENGINEDRIVEN DRILLS INDICATIONS 55 Old patients An external oblique ridge and internal oblique ridge or both are far formed in relationship to the tooth Hence guttering is necessary to avoid excess removal of bone COMPLICATIONS Accidental denuding of roots of 2nd molar While guttering the bone the mandibular canal may be opened and damage to nerve may occur While cutting distolingual part of bone high chance of lingual nerve damage hence it should be moved lingual to buccal to prevent sudden slipping into lingual side
- 56. Bur technique Thesize of the bur used for the removal of the bone removal : Ideal length – 7mm; diameter – 1.5mm. The bur should rotate in correct direction and at maximum speed. Cutting instruments that induce air should’nt be used. Handpiece should not rest on the tissues of the cheek and lips to avoid burning 56
- 57.
- 58. The crown ofthe impacted tooth should be exposed (CEJ) by removal of surrounding bone: mesially – to create a point of application Buccaly – cutting a trough or gutter around the tooth to the root furcation. Distolingually – lingual plate should not be breached to protect the lingual nerve. 58
- 59. Irrigation The surgeonsshould apply a handpiece load of approximately 300g and an irrigation rate of 15 mL/min (for intermittent drip) to 24 mL/min (for continuous flow). (Sharon et al Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1999) The various solutions which can be used as irrigants are: Normal Saline Ringer’s lactate. 1% povidone iodine 59
- 60. The irrigation coolsthe bur and prevents bone- damaging heat buildup. The irrigation also increases the efficiency of the bur by washing away bone chips from the flutes of the bur and by providing a certain amount of lubrication. 60
- 61.
- 62. Bone belongs tothe patient and the tooth belongs to the surgeon. Pell and Gregory stated the following advantages of splitting technique: Amount of bone to be removed is reduced. The time of operation is reduced. The field of operation is small and therefore damage to adjacent teeth and bone is reduced. Risk of jaw fracture is reduced. Risk of damage to the inferior alveolar nerve is reduced 62 Sectioning of the tooth
- 63. CRITERIA TO DECIDEIF SECTIONING OF TOOTH IS INDICATED 63
- 64. Sectioning of thetooth based on the type of impaction Horizontal impactions - the crown is separated from its roots and removed first. The roots are themselves divided and removed individually into the space vacated by the crown. Vertical impactions - the tooth is divided in half along its vertical axis and each half removed individually. 64
- 65. 65 Disto-angular impactions -the tooth may be divided in half along its longitudinal axis or the crown may be sectioned from its roots with the roots being elevated into the space vacated by the crown. Mesio-angular impactions - the tooth may be divided in half along its longitudinal axis or the crown may be divided obliquely with the distal segment removed first prior to mobilizing the rest of the tooth.
- 66.
- 67. DEBRIDMENT AND IRRIGATION 67 AFTERREMOVAL OF TOOTH All particulate bone chips and debris should be debrided Thorough irrigation with sterile saline including under the reflected soft tissue flap A periapical curette can be used
- 68. COMPLICATIONS OF THIRDMOLAR SURGERY Surgical extraction of third molars is often accompanied by pain, swelling, trismus, and general oral dysfunction during the healing phase. Complications related to third molar removal range from 4.6% to 30.9% INTRAOPERATIVE During incision Facial or buccal vessel may be cut Lingual nerve injury Bleeding from Retromolar vessels During bone removal Damage to second molar and roots Fracture of mandible Bleeding 68
- 69. DURING ELEVATION Crown fracture root fracture fracture of the jaws slipping of tooth into lingual pouch damage to nerve aspiration of the tooth DURING DEBRIDEMENT Damage to inferior alveolar nerve 69
- 70. Injudicious useof force during removal of the tooth, a deeply impacted tooth, and osteoporosis and other metabolic bone disorders or lesions, such as cysts or tumours, increase the likelihood of fracture. The presence of an impacted tooth in a severely atrophic mandible, or infection involving the bone surrounding the tooth, may also predispose to fracture. 70
- 71. DAMAGE TO NERVE The incidence of lingual and IAN injuries reported ranges from 0.4% to 22%. The incidence of neurologic injuries from third molar surgery may be related to multiple factors, including surgeon experience and proximity of the tooth relative to the IAN canal. 71
- 72. Conclusion Surgical removal ofimpacted tooth is a stressful experience for many patients.. As each patient and each surgical procedure are unique , surgeons should carefully assess the risk factors of removal of impacted tooth by proper diagnosis and choose correct surgical techniques to avoid surgical complications & minimizing adverse side effects thereby making the surgical experience more favorable for patients . 72
- 73. BIBLIOGRAPHY Peterson’s Principlesof oral and maxillofacial surgery, 2nd edition, vol. 1. Textbook of oral and maxillofacial surgery, vol. 2, Laskin. Textbook of oral and maxillofacial surgery- Kruger Oral and maxillofacial surgery-Archer Surgery of the mouth and jaws-Moore OMFS CLINICS OF NA VOLUME 19 FEB 2007 73
- 74.