This document provides an overview of impacted third molars and their surgical removal. It discusses terminology, classifications, development, indications, contraindications and complications. Common classifications described include Winter's classification based on angulation and Pell & Gregory's classification analyzing anatomical relationships. Key points are that third molars are the last to erupt, between ages 18-25, and may become impacted due to insufficient jaw size or other impediments, leading to surgical removal which is one of the most common procedures in oral surgery. Careful planning is required due to potential complications.

2. CONTENTS
• Introduction
• Terminology and definitions
• Why teeth get impacted?
• Indications and contraindications
• Development of mandibular third molar
• Classifications of impacted mandibular
third molar teeth
• Radiographical investigation

3. CONTENTS
• Surgical anatomy
• Instrument tray setup
• Operative procedure of Impacted Lower
Third Molar
• Surgical Removal of Impacted Maxillary
Third Molar
• Postoperative Care and Instructions

4. CONTENTS
• Drug Therapy
• Complications of Impaction Surgery
• Ectopic Teeth and Unusual Cases
• Recent Advances and the Future of Third
Molars

5. Introduction
• Although the scope of oral and maxillofacial surgery
has expanded in many directions recently, the
mainstay of practice remains dentoalveolar surgery.
• The atraumatic removal of impacted teeth is one of
the most commonly performed surgical procedures
in the specialty of oral and maxillofacial surgery.

6. • Berge T.I and Gilhuus-Moe O.T (1993) showed that
there is a four fold increase in the incidence of
complications when the surgery was performed by
the general practitioner as compared that
performed by the oral surgeon.
• This difference in complication rates may be
attributed to inadequate surgical training and lack of
experience of the former.

7. • A thorough theoretical knowledge and
adequate clinical training is essential to
perform the surgery successfully.

8. Definitions
• 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.”

9. Mead (1954 ) An impacted tooth as a tooth that is
prevented from erupting into position
because of malposition, lack of space,
or other impediments.
Rounds (1962) A precise definition of impaction as
the condition in which a tooth is
embedded in the alveolus so that its
further eruption is prevented.

10. Definitions
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.

11. 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 teeth is any tooth that is
prevented from reaching its normal
position in the mouth by tissue, bone or
another tooth.

12. Terminology

13. Why teeth get impacted?
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”.

14. A number of theories has been put forward to
explain the incident 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)

15. 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.

16.  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.

17. 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 :

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

19. 4) Endocrinal theory:
Increase or decrease in growth hormone
secretion may affect the size of the jaws.

20. 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.

22.  Mandibular 3rd molars
 Maxillary 3rd molars
 Maxillary cuspid
 Mandibular bicuspids
 Maxillary bicuspids
 Mandibular canine
 Maxillary central and lateral incisors
FREQUENCY OF IMPACTION

23. Causes
In 1930 Berger lists the causes of impaction:
Local causes
Systemic causes

24. Local Causes
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.

25. 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

26. Systemic Causes
i. Prenatal causes
ii. Post natal causes
iii. Rare conditions

27. I. Prenatal causes: • Hereditary
• Miscegenation
II. Post natal causes : • Rickets
• Anemia
• Congenital Syphilis
• Tuberculosis
• Endocrine Dysfunction
• Malnutrition.

28. III. Rare conditions: • Cleidocranial dysplasia
• Oxycephaly
• Progeria
• Achondroplasia
• Cleft palate.

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

30. Therapeutic indications
• Recurrent or severe pericoronitis.
• Periodontal disease with a pocket depth of 5 mm or
more distal to the second molar.
• Non-restorable caries in the third molar.
• Resorption of the third molar or adjacent tooth.

31. • Apical periodontitis.
• Cysts or tumors associated with the third molar (or
adjacent tooth).
• When required for orthognatic surgery.
• Removal of third molar in a fracture line.

32. Prophylactic indication
• 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.

33. Prophylactic indications for medically
needful
• Prior to radiation therapy for head and neck
malignancies;
• Prior to organ transplantation;
• Chemotherapy;
• Bisphosphonate therapy.

34. Prophylactic indication for surgical
reasons-
• The presence of a third molar in a fracture line.
• Prior to orthognatic surgery.
• When a third molar may be considered for
autogenous transplantation, usually to a first molar
region.

35. • When the third molar region is involved in tumor
• Resection or jaw reconstruction surgery.

36. NICE Guidelines for the Removal of
Wisdom Teeth

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

38. (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

39. e. Cellulitis or abscess formation
f. Osteomyelitis
g. Tooth/teeth impeding surgery, e.g. reconstructive
jaw surgery, preprosthetic/implant surgery,
orthognathic surgery.

40. (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.

41. • 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.

42. Contraindications
•Extremes of Age
•Surgical Damage to adjacent Structures
•Compromised Medical Status
•Prosthetic considerations
•Socioeconomic reasons

43. Mandibular 3rd molar

44. Development of mandibular third
molar
 Third molars are the only teeth that develop
entirely after birth.

45. 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

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

48. 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

50. WINTER’S SUB CLASSES
• The angle between the occlusal plane or line
parallel to it and the longitudinal axis of the
impacted third molar, in turn, allowed objective
classification of the third molars within the
Winter subclasses as follows

51. 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

52. Third molars with
an angle between
61° to 90°
Vertical
Third molars with
an angle (-90°)
Distoangular

53. Pell & Gregory’s classification (1933)
• 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

54. 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

55. 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

56. 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

57. 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

58. Killey & Kay’s classification (1979)
a) Based on angulation and position: Same as
Winter’s classification
b) Based on the state of eruption:
Completely eruption
Partially erupted
Unerupted

59. c) Based on roots:
1) Number of roots - Fused roots
Two roots
Multiple roots
2) Root pattern - Surgically favorable
-Surgically unfavorable

60. Based on clinical and radiographic
interpretation of the tissue overlying the
impacted teeth.
Combined ADA & AAOMS
classification of procedural
terminology

61.  07220-Soft tissue impaction
 07230-Partial bony impaction
 07240-Complete bony impaction
 07241-Complete bony impaction with unusual
surgical complications

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

63. Quek et al. (2003) classification of
impaction
 Vertical impaction (10° to -10°)
 Mesioangular impaction (11° to 79°)
 Horizontal impaction (80° to 100°)
 Distoangular impaction ( -11° to -79°)
 Others (111° to -80°)

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

65. 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.

66. 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

67. TMC I TMC II a

68. TMC IIITMC IIb

69. 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.

70. Class O: The mandibular
canal is not visible on the
images (plexiform canal).

71. 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

72. 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.

73. 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.

74. 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.

75. 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.

76. Class6: 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.

77. Class 7: The mandibular canal runs between fused roots

78. Difficulty index
• WHARFE assessment - Macgregor 1985
• Pederson’s scale ,1988
• Parant scale

79. 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 3rd
molar (degrees)
1-59 0
60-69 1
70-79 2
80-89 3
90+ 4
WHARFE’S ASSESSMENT by McGregor 1985

80. Root shape &
development
Complex 3 (more than 2/3 complete)
Unfavourable curvature 2 (less than1/3 complete)
Favourable 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

81. 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

82. Difficulty index for removal of third molar
(PEDERSON’S SCALE, 1988)
RAMUS RELATIONSHIP
Class I 1
Class II 2
Class III 3

83. Pederson’s Difficulty index
Very difficult : 7 to 10
Moderately difficult : 5 to 7
Minimally difficult : 3 to 4

84. Modified Pederson’s Difficulty index
Very difficult = 7–10
Moderately difficult = 5–6
Slightly difficult = 3-4

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

86. Recent advance in grade of difficulty
• Kharma’s scale ,2014

87. 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

88. 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

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

90. Surgical anatomy of mandibular 3rd
molar
Occlusal view Coronal section

91. Vitals structure surrounds mandibular 3rd
molar
i. Bone trajectories of mandible
ii. Lingual plate
iii. Musculature
iv. Neurovascular Bundle
v. Retromolar triangle
vi. Facial artery and vein
vii. Lingual nerve
viii.Mylohyoid nerve
ix. Long buccal nerve

92. Bone trajectories of mandible
(Grain of mandible)
• A line of stress extends from one condyle to the
other passing along the symphysis.

93. • A no: of trajectories radiate down below the
roots of teeth

94. Surgical implication
– 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

95. • 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.
Lingual plate

96.  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'.

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

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

99. Buccinator
―This horseshoe-shaped muscle forms the musculature
of the cheek. It is inserted along the external oblique
ridge and continues along the pterygomandibular
raphe.
―It is attached to the maxilla at the level of the apices
of molar roots.

100. Surgical implication
―During surgical removal deeply seated impacted
tooth require detachment of this muscle
– Lead to postoperative swelling, trismus & pain.

101. • Temporalis
― 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 tendon.
Inner tendon.

102. ―The outer tendon is inserted to the anterior border
of coronoid process.
―The inner tendon is attached to the temporal crest of
mandible.
―The retromolar fossa is found in between these
tendons.

103. • 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.

104. Masseter
―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.

105. Medial pterygoid
―This is 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

106. Mylohyoid
―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.

107. Neurovascular Bundle
 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.

108. 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.

109. Retromolar triangle
• 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

110. 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.

111. Facial artery and vein
–Cross the inferior border of mandible anterior to
masseter muscle near to 2nd molar

112. 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.

113. Lingual nerve
• 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.

115. • 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
Four anatomical risk of lingual nerve
( Len Tolstunov 2007)

116. • 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

117. Mylohyoid nerve
• This nerve leaves IAN before entering mandibular canal
• Then penetrate the sphenomandibular ligament.

118. Surgical implication
• In 16% of cases this nerve present in too close
proximity of canal
• Damage may take place during lingual approach
for removing 3rd molar tooth.

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

120. Surgical implication
 During wide opening of mouth it lies above the
retro molar fossa region.
 Injury is rare but can occur if incision is placed too
laterally into the buccal mucosa.

121. RADIOLOGY

122. Background
• 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.

123. Background
• The discovery of X-rays in1895 was a very
important step in treatment planning for third
molar surgery.

124. • According to Sonnabend (1973) the first
dental radiograph was taken by Professor
Giesel of Berlein only two weeks after
Rontgen’s discover.

125. • Morton (1896),the first American to take intraoral
radiograph.
• One year later Dr. William Jarvie of New York was
saying how useful it would be, according to him ‘ In
cases of impacted third molars we could get to know
the exact location of the roots’.

126. • In 1913, father of exodontia G.B Winter, provided the
guidelines to make proper radiograph of impacted 3rd
molars.
• The first publication of his findings appeared in
'Dental Items of Interest' under the title of
'Exodontia', a term which he himself has coined.

127. • A revised and much enlarged second edition was
printed in 1926 and the title was changed to 'The
Impacted Mandibular Third Molar'.

128. • In this book content 200 pages on the radiography of
lower third molars related to their extraction and no-
one could write again on the subject without
referring to Winter’s classifications.

129. Radiolographs
OrthopantamographIntraoral periapical

130. Radiolographs
Linear cross sectional
tomography
Lateral oblique view

131. Radiographs of third molars must
show
• Access
• 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

132. ( 1926 )
• Assessment of depth of tooth in alveolar bone
• Using roots of 2nd molar as a guide
Winter’s WAR line

133. Position And Depth Of Impacted Tooth
• White Line
• Provide information
regarding the depth
& inclination

134. 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.

135. • 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

136. Rood criteria
• 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.

137. Darkening of root Deflection of root
Related to Root

138. Narrowing of root Bifid root apex
Related to Root

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

140. Use of CT scan
• Helps to show relationship of root apices with
inferior dental canal.
• Useful to predict the bone density of mandible

141. Use of CBCT

142. • When OPG suggest close relationship between root
apex and madibular canal
• Information about distance between IAN & lower
tooth root
• Prediction for risk of damage of IAN.

143. Advantages :
Radiation exposure 10 times less than regular
CT scan
• Required less time(10-40 sec) than
conventional CT
• Price is comparatively less than CT scan
(<50%)

144. • OPG is a good method for preoperative evaluation of
surgical lower 3rd molar extraction.
• The absence of radiographic signs associated with a
relationship between the lower 3rd molar and the
canal indicates a minimum risk of nerve damage.

145. Thank you