Detailed description on management of impacted maxillary and mandibular third molars. Surgical approaches and complications are also discussed in details.

1. Presented by Dr Dibya Falgoon Sarkar

2. Contents of Part I
•Introduction
•Terminology and definitions
•Why teeth get impacted?
•Indications and contraindications
•Development of mandibular third molar
•Classifications of impacted mandibular third
molar teeth
•Radiography and investigations
•Surgical anatomy

3. Contents of Part II
•Instrument tray setup
•Operative procedure of Impacted Lower Third Molar
•Surgical Removal of Impacted Maxillary Third Molar
•Postoperative Care and Instructions
•Drug Therapy
•Complications of Impaction Surgery
•Ectopic Teeth and Unusual Cases
•Recent Advances and the Future of Third Molars

4. • Evaluation and management of impacted teeth are among the most
frequent services offered by oral & maxillofacial surgeons
• Reddy et al (JOMS 2012) showed that the overall prevalence of third
molar impactions is about 18.6% among Indian population
• Berge T.I and Gilhuus-Moe O.T (1993) showed that there is a four fold
increase in the incidence of complications of impaction cases when the
surgery was performed by a general practitioner as compared to that
performed by an oral surgeon.
• This difference in complication rates may be attributed to inadequate
surgical training and lack of experience of the former.

5. •The term impaction is derived from Latin word
'impactus’.
•Impactus means, “An organ or structure which
because of an abnormal mechanical condition has
been prevented from assuming its normal
position.”

6. Mead (1954 ) An impacted tooth is a tooth that is
prevented from erupting into position
because of malposition, lack of space, or
other impediments.
Archer (1975) 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.

7. Andreasen et al
(1997)
A cessation of the eruption of a tooth
caused by a clinically or radiographically
detectable physical barrier in the eruption
path or by an ectopic position of the tooth.
WHO (2007) An impacted tooth is any tooth that is
prevented from reaching its normal
position in the mouth by tissue, bone or
another tooth.

8. • The third molars or the wisdom teeth normally
erupt last, between 18 and 25 years of age.
• John hunter (1771) is one of the early authors
who noted “want of room in the jaws for these
late teeth” and he also suggested as a cause that
“the jaws had left off growing”.

9. A number of theories has been put forward to explain the
cause of impaction. The most commonly accepted ones are the
following:
•Phylogenic theory (Nodine 1943)
•Mendelian theory
•Orthodontic theory(Durbeck 1881)
•Endocrinal theory
•Anthropological theory (Mac Gregor 1985)

10. 1) Phylogenic theory (Nodine):-
 This theory motivated from Lamarck’s disuse theory.
 According to his theory if the particular body part is not
used it will disappeared. 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.

11. Small Jaws
And Large
Teeth
Small Jaws And
Small Teeth
Large Jaws And
Large Teeth
Large Jaws
And Small
Teeth
Small Jaws
And Small
Teeth
Large Jaws
And Large
Teeth
2) Mendelian theory :

12. 3) Orthodontic theory (Durbeck 1881):-
Growth of the jaw
Movement of teeth
Forward direction
Acute infections,
Fever,
Severe trauma
Retardation of forward
growth
Normally

13. 4) Endocrinal theory:
Increase or decrease in growth hormone secretion may affect the
size of the jaws.
5) Anthropological theory (Mac Gregor 1985)
According to this theory human beings alone underwent a period
of evolution in which the brain greatly expanded in size and the jaw
had to become narrower.

14.  Mandibular 3rd molars
 Maxillary 3rd molars
 Maxillary cuspid
 Mandibular bicuspids
 Maxillary bicuspids
 Mandibular canine
 Maxillary central and lateral incisors

15. In 1930 Berger lists the two main causes of impaction:
1. Local causes
2. Systemic causes

16. 1. 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 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

17. Systemic causes
Prenatal causes
Hereditary
Miscegenation:
Interbreeding of people
considered to be of different
racial types
Post natal causes
Rickets
Anemia
Congenital Syphilis
Tuberculosis
Endocrine Dysfunction
Malnutrition.
Rare conditions
Cleidocranial dysplasia
Oxycephaly
Progeria
Achondroplasia
Cleft palate.

18. •There are two types of indications for removing
impacted teeth
I. Therapeutic indications
II. Prophylactic indication

20. •Prophylactic removal of a non-erupted tooth is by
definition a surgical intervention to prevent future
disease.
•This practice is often referred to as “removal of
asymptomatic third molars”. It is important to
define this subject more precisely.

21. •Prior to radiation therapy for head and neck
malignancies.
•Prior to organ transplantation.
•Chemotherapy
•Bisphosphonate therapy

22. •The presence of a third molar in a fracture line.
•Prior to orthognathic surgery.
•When a third molar may be considered for
autogenous transplantation, usually to a first molar
region.
•When the third molar region is involved in tumor
•Resection or jaw reconstruction surgery.

23. (1) The routine practice of prophylactic removal
of pathology-free impacted third molars should
be discontinued in the National Health Service.

24. (2) Surgical removal of impacted third molars should be limited
to those with evidence of pathology, such as the following:
a. Unrestorable caries
b. Fracture of tooth
c. Non-treatable pulpal and/or periapical pathology
d. Pathology of follicle including cyst/tumour
e. Cellulitis or abscess formation
f. Osteomyelitis
g. Tooth/teeth impeding surgery, e.g. reconstructive jaw surgery,
preprosthetic/implant surgery, orthognathic surgery.

25. (3) Specific attention is drawn to plaque formation and
pericoronitis. Plaque formation is a risk factor but is not
itself an indication for surgery. The degree to which the
severity of recurrence rate of pericoronitis should influence
the decision for surgical removal of a third molar remains
unclear.
• The evidence suggests that a first episode of pericoronitis,
unless particularly severe, should not be considered an
indication for surgery.
• Second or subsequent episodes should be considered as an
appropriate indication for surgery.

26. Extremes of age
Surgical damage
to adjacent
structures
Compromised medical
status: Congenital
coagulopathies,
asthma, epilepsy, etc.
Prosthetic
considerations
Socioeconomic
reasons

27. Mandibular 3rd molar

28.  Third molars are the only teeth that develop entirely after birth.
The stages of the development and eruption of mandibular third molar
according to the years :
Tooth germ visible 9 yrs
Cusp mineralization 11 yrs
Crown formation 14 yrs
Roots formed (apex open) 18 yrs
Eruption 18-24 yrs

30. •George Winter’s classification (1926)
•Pell & Gregory’s classification (1933)
•Killey & Kay’s classification (1979)
•Combined ADA & AAOMS classification of
procedural terminology

31. George Winter’s classification (1926)
Based on the relationship of the long axis of
the impacted tooth in relation to the long axis
of the 2nd molar
i. Mesioangular
ii. Vertical
iii. Horizontal
iv. Distoangular
v. Buccoangular
vi. Linguoangular
vii. Transverse
viii. Inverted

33. Winter’s sub classes
• The angle between the
occlusal plane or line
parallel to it and the
longitudinal axis of the
impacted third molar.
• Winter subclasses as
follows:
Third molars with
negative angles
(-0°)
Inverted
Third molars with
an angle between
0° to 30°
Horizontal
Third molars with
an angle between
31° to 60°
Mesioangular
Third molars with
an angle between
61° to 90°
Vertical
Third molars with
an angle (>90°)
Distoangular

34. • Analysis of the potential anatomic problems involved preparatory to
the removal of lower 3rd molar
1. Relation of the tooth to the ramus of the mandible
2. Relative depth of the third molar in bone

35. Relation of the tooth to the ramus of the mandible
 Class I
Relative depth of the third molar in bone
I. Position A
II. Position B
III. Position C

36. Relation of the tooth to the ramus of the mandible
 Class II
Relative depth of the third molar in bone
I. Position A
II. Position B
III. Position C

37. Relation of the tooth to the ramus of the mandible
 Class III
Relative depth of the third molar in bone
I. Position A
II. Position B
III. Position C

38. 3. The position of the tooth in relation to the long axis of the second
molar
i. Vertical
ii. Horizontal
iii. Inverted
iv. Mesioangular
v. Distoangular

39. a) Based on angulation and position: Same as Winter’s classification
b) Based on the state of eruption:
Completely eruption
Partially erupted
Unerupted
c) Based on roots:
1) Number of roots - Fused roots ,two roots, multiple roots
2) Root pattern - Surgically favorable
-Surgically unfavorable

40. Based on clinical and radiographic interpretation of the tissue overlying
the impacted teeth.
 07220-Soft tissue impaction
 07230-Partial bony impaction
 07240-Complete bony impaction
 07241-Complete bony impaction with unusual surgical complications
Combined ADA & AAOMS classification of
procedural terminology

41. •Quek et al. (2003) classification of impaction
•Operative Classification (2010)
• Classification of impacted mandibular third molars on
cone-beam CT images (2015)

42. Vertical impaction (10° to -10°)
Mesioangular impaction (11° to 79°)
Horizontal impaction (80° to 100°)
Distoangular impaction ( -11° to -79°)
Others (111° to -80°)

43. Quek et al. (2003) classification of impaction, a system of
measurement , using protector.

44. Operative Classification of Impacted Molars (2010)
• The mandibular third molar is classified according to its position
relative to the mandibular canal using a standard panoramic x-ray.
• There are 3 major types of third molar positions.
TMC I Roots of the third molar above the mandibular
canal
TMC IIa Mandibular third molar roots are in relation to the
mandibular canal
TMC IIb More than a third of the molar roots are in
relation to the mandibular canal
TMC III All third molars roots are localized below the
mandibular canal

45. TMC I TMC II a
TMC IIb TMC III

46. Classification of impacted mandibular third
molars on cone-beam CT images
Maglione M. et al (2015) introduce a new
radiological classification that could be normally used
in clinical practice to assess the relationship between
an impacted third molar and mandibular canal on
cone beam CT (CBCT) images.

47. Class O: The mandibular canal is not
visible on the images (plexiform
canal).
Class 1: The mandibular canal runs
apically or buccally with respect to
the tooth but without touching it
(the cortical limitations of the
canal are not interrupted).
1A: The distance IAN and tooth is
greater than 2 mm.
1B: The distance IAN and tooth is
less than 2 mm

48. Class 2: The mandibular canal runs lingually with
respect to the tooth but without touching it (the
cortical limitations of the canal are not interrupted).
2B: The distance IAN
and tooth is less than 2
mm.
2A: The distance IAN and
tooth is greater than 2
mm.

49. Class 3: The mandibular canal runs apical or buccal
touching the tooth.
3A: In the point of
contact the
mandibular canal
shows a preserved
diameter.
3B: In the point of
contact the mandibular
canal shows an
interruption of the
corticalization.

50. Class 4: The mandibular canal runs lingually touching
the tooth.
4A: In the point of
contact the mandibular
canal shows a preserved
diameter.
4B: In the point of
contact the mandibular
canal shows an
interruption of the
corticalization.

51. Class 5: The mandibular canal runs between the roots
but without touching them
5A: The distance IAN
and tooth is greater
than 2 mm.
5B:The distance IAN and
tooth is less than 2 mm.

52. • Class 6: The mandibular canal runs between the roots touching
them.
6A: In the point of
contact the mandibular
canal shows a preserved
diameter.
6B: In the point of contact
the mandibular canal
shows an interruption of
the corticalization.
• Class 7: The mandibular canal
runs between fused roots

53. •WHARFE assessment - Macgregor 1985
•Pederson’s scale (1988)
•Parant scale

54. Criteria Category Score
Winters
Classifications
Horizontal 2
Distoangular 3
Mesioangular 1
Vertical 0
Height of
mandible (mm)
1-30 0
31-34 1
35-39 2
Angulation of 2nd
molar (degrees)
1-59 0
60-69 1
70-79 2
80-89 3
90+ 4
WHARFE’S ASSESSMENT by McGregor 1985

55. Root shape &
development
Complex 3 (more than 2/3 complete)
Unfavorable curvature 2 (less than1/3 complete)
Favorable curvature 1
Follicles Normal 0
Possibly enlarged -1
Enlarged -2
Impaction relieved -3
Path of exit Space available 0
Distal cusps covered 1
Mesial cusps also
covered
2
Both covered 3
TOTAL 33

56. Difficulty index for removal of third molar (PEDERSON’S SCALE, 1988)
ANGULATION/SPATIAL RELATIONSHIP
Mesioangular 1
Horizontal/Transverse 2
Vertical 3
Distoangular 4
DEPTH
Level A 1
Level B 2
Level C 3
Difficulty index for removal of third molar (PEDERSON’S SCALE, 1988)
RAMUS RELATIONSHIP
Class I 1
Class II 2
Class III 3

57. Modified Pederson’s Difficulty index
Pederson’s Difficulty index
Very difficult : 7 to 10
Moderately difficult : 5 to 7
Minimally difficult : 3 to 4
• Very difficult = 7–10
• Moderately difficult = 5–6
• Slightly difficult = 3-4

58. Easy I Extraction requiring forceps only
Easy II Extraction requiring osteotomy
Difficult III Extraction requiring osteotomy and
coronal section
Difficult IV Complex extraction ( root resection)

59. Difficulty index for removal of third molar (Kharma scale ,2014)
ANGULATION/SPATIAL RELATIONSHIP
Mesioangular 0
Horizontal/Transverse 1
Vertical 2
Distoangular 3
DEPTH
Level A: high occlusal 1
Level B: medium occlusal 2
Level C: deep occlusal 3

60. ROOTS FORM
Convergent 0
Divergent 1
Bulbous 2
RAMUS RELATIONSHIP
Class I: Sufficient Space 0
Class II: Reduced Space 1
Class III: No Space 2

61. Modified Difficulty index
(According to the Kharma’s scale)
Very difficult 7–10
Moderately difficult 5–6
Slightly difficult 3-4
Easy 1-2

62. Occlusal view Coronal section

63. i. Lingual plate
ii. Musculature
iii. Neurovascular Bundle
iv. Bone trajectories of mandible
v. Retromolar triangle
vi. Facial artery and vein
vii. Lingual nerve
viii.Mylohyoid nerve
ix. Long buccal nerve

64. • A line of stress extends from one condyle to the other passing along the
symphysis.
• A number of trajectories radiate down below the roots of teeth

65. Surgical implication of trajectories
• Importance lies in use of chisel for
bone removal.
• Buccal horizontal cut may extend from
1st molar till distal to 3rd molar till ramus
and cause fracture.
• To prevent from such incident vertical
stop cut need to be placed mesial and
distal to the 3rd molar

66. • The lingual plate is the side of the lower jaw tooth
socket nearest the tongue.
• In the region of the lower 3rd molar.
• The lingual plate can often be very thin.
Surgical implications
• Because of the extreme thinness of the
lingual plate the apices of lower third molar
frequently perforates it.
• Attempted elevation of fractured roots may
lead to their displacement through the thin
lingual cortex into the 'lingual pouch'.

67. Fracture of lingual plate:
• Difficulty will be experienced in
retrieving such dislodged root
fragments.
• Rarely the whole tooth may be pushed
into the lingual pouch.
Whole tooth may be displaced
into the lingual pouch under the
mylohyoid muscle

68. Musculature
The various muscles surrounding the third molar
region are:
• Buccinator - Anteriorly
• Temporalis - Distally
• Masseter - Laterally
• Medial Pterygoid And Mylohyoid - Medially

69. ―This horseshoe-shaped muscle forms the
musculature of the cheek.
―Inserted along the external oblique ridge
and continues along the pterygomand
raphe.
Surgical implication
―During surgical removal deeply seated
impacted tooth require detachment of this
muscle
– Lead to postoperative swelling, trismus &
pain.

70. • This fan-shaped muscle is inserted on the
coronoid process and anterior border of
mandible.
• Two tendons can be noticed where the
muscle attaches to the anterior border of
mandible: outer and inner tendon
• Surgical implication
―During buccal approach for the removal of
third molars, the outer tendon has to be
sectioned to enable reflection of the flap.
― This in turn will help to remove adequate
bone from the buccal and distal side.

71. ―This muscle is inserted into the
lateral side of the ramus from the
coronoid process up to the angle.
―Rarely involved in third molar
surgery.
―Postoperative edema may involve
posteriorly to the muscle leading
to trismus and pain.

72. ―Its inserted on the medial
aspect of mandible in the angle
region.
―Not directly involved in third
molar surgery.
―But during lingual approach
postoperative edema involve
this muscle which can lead to
trismus due to secondary
involvement of the muscle

73. ―This muscle is inserted on the
mylohyoid line from canine to
the third molar region.
―During lingual approach this
muscle can partly sever may lead
to transient swallowing difficulty.
―Postoperative infection can
spread to sublingual /
submandibular space through
this muscle breakage.

74. The neurovascular bundle contains the inferior alveolar
artery, vein and nerve enclosed in a fascial sheath.
The radiographic evaluation of the relationship of the
mandibular canal and roots of the third molar forms an
important part of the preoperative assessment.

75. The inferior alveolar canal deroofed as part of a marginal mandibular resection showing
neurovascular vessels in third molar region. The vein (V) lies superiorly, and the artery (A)
lies lingually and superiorly. The inferior alveolar nerve (N) lies below.
Castellon et al performed a prospective study in 1117 patients and concluded that
patient age, ostectomy of the bone distal to the third molar, the radiologic relationship
between the roots of the third molar and the mandibular canal, and deflection of the
mandibular canal increased the risk of IAN damage. ( Incidence 5%)

76. • Kilic et al performed a study to identify the position of the mandibular canal through
direct measurement and to determine the branches of the inferior alveolar nerve
through histologic examination on 26 human cadavers
They concluded that the mandibular canal was located at a mean distance of 10.52
mm above the inferior margin of the mandible. (Clinical Anatomy 23:34–42 (2010))
• Miloro et al conducted a radiographic study to determine the distance between
mandibular third molars and the mandibular canal using OPGs
They concluded that unerupted molars and mesioangular impacted molars were
most closely positioned and were risk factors for post op paresthesia
(OOOO journal 2005; 100: 545-9)
• Levine et al conclude that the IAN canal was 4.9 mm and 17.4 mm from the buccal
and superior cortical surfaces of the mandible, respectively. Older patients and white
patients, on average, have lesser distance. ( JOMS 65: 470-474;2007)

77. • Depressed roughened area – bounded by buccal &
lingual crest.
• Lateral to this – retromolar fossa.
Through this branches of retromolar nutrient vessels
emerges and supply temporalis tendon, buccinator
muscle and adjacent alveolus
• Surgical implication
• If the distal incision is extended on ramus instead of
extending over cheek – cause injury to retromolar
nutrient vessels – lead to rapid bleeding.
• Excessive distal extension of incision may cause
incision of temporalis attachments and may lead to
post operative trismus

78. • Cross the inferior border of mandible
anterior to masseter muscle near to 2nd
molar
• Surgical implication
Injury may occur due to slippage of the BP
blade while making vertical realising
incision.
It is better to start incision from buccal
sulcus then extend upward to the tooth.

79. •The lingual nerve lies on the
medial aspect of the third molar.
•Frequently lingual nerve courses
submucosally in contact with the
periosteum covering the lingual
wall of the third molar socket or it
may run below and behind the
tooth.

80. • The average diameter of the nerve was 1.86 mm.
• In the lower third molar region 61.7% of the lingual nerves were round.
• Out of 256 cases, 4.5% cases showed that the nerve lied above the
alveolar crest

81. Four anatomical risks of lingual nerve:
( Len Tolstunov 2007)
• Lingual version of distoangular impacted lower 3rd molar
• Root of few distoangular 3rd molar directed lingually – lingual version – increase the
vulnerability with lingual nerve
•Lingual plate deficiency
• Root Apices of third molar penetrate the lingual plate – deflected into lingual pouch –
injure the lingual nerve
• High lateral position of lingual nerve
• Lingual nerve can be in full contact with lingual plate / above the lingual plate –
increase vulnerability of lingual nerve
• Local chronic inflammatory condition
• Long standing pericoronal infection lead to scaring of lingual nerve with lingual plate
• If lingual plate is deficient then its tend to attached with the 3rd molar tooth

82. Mylohyoid nerve
• This nerve leaves IAN before it enters into mandibular canal
• Then penetrate the sphenomandibular ligament.

83. Long buccal nerve
•Emerges through the buccinator and passes
anteriorly on its outer surface

84. • The operation of removing a lower third molar can have serious
complications if it is not planned with some care.
• All features like size, shape, position of the tooth and consistency of
bone can all be demonstrated on a radiograph.

85. Radiographs
OrthopantamographIntraoral periapical

86. Radiographs
Linear cross sectional
tomography
Lateral oblique view

87. •Position & depth of impacted tooth
•Root pattern of impacted teeth
•Shape of crown
•Texture of investing bone
•Relation to inferior alveolar canal
•Position & root pattern of second molar

88. • hite Line
• Provide information regarding the
depth & inclination
• Amber Line
• Indicate the margin of the alveolar
bone enclosing the teeth.
• One must differentiate between
external oblique ridge and bone lying
distal to impacted tooth.
• Red Line
• Provides information about depth at
which elevator should be applied
• Longer the line difficult to remove/access
the tooth
• Length : difficulty :: 1 : 3

89. •In 1990, Rood and Shehab , in a literature review,
collected seven radiographic indicators of a close
relationship between the lower 3rd molar and the
inferior alveolar canal.

90. Narrowing of root Bifid root apex
Darkening of root Deflection of root
Related to inferior alveolar canal

91. Diversion of canal
Interruption in white line of canal.
Narrowing of canal
Related to inferior alveolar canal

92. • Helps to show relationship of root apices with inferior dental
canal or the maxillary sinus floor
• Useful to predict the bone density of mandible
• Useful for obtaining a 3D spatial orientation of the third molar
inside the mandible/ maxilla

93. Use of CBCT

94. • Indications:
1. When OPG suggest close relationship between root apex and
madibular canal
2. Information about distance between IAN & lower tooth root
3. Prediction for risk of damage of IAN.
• Advantages :
1. Radiation exposure 10 times less than regular CT scan
2. Required less time(10-40 sec) than conventional CT
3. Price is comparatively less than CT scan (<50%)
CBCT Scan