This document provides an overview of assessing the difficulty of removing mandibular impacted third molars. It discusses the importance of a thorough history and clinical/radiographic examination to determine factors like depth, position, root morphology and proximity to anatomical structures that can influence difficulty. A standardized index uses Winter's lines on radiographs to classify depth as predictive of difficulty, with deeper impactions requiring more bone removal and posing greater challenges. A multifactorial assessment allows for an individualized treatment plan.

1. ASSESSMENT OF DIFFICULTY OF
MANDIBULAR IMPACTED THIRD
MOLARS
Presented by : Dr.Preeti Satish

2. Contents
• Introduction
• History
• Clinical assessment
• Factors predictive of difficulty
• Difficulty index
• Conclusion

3. Introduction
• The extraction of third molars is among the most common
surgical procedures and is a cornerstone of the field of
oral and maxillofacial surgery.
• A successful 3rd molar surgery is dependent upon-
detailed pre-operative assessment and treatment
planning
• Mac Gregor (1979) made the first attempt to establish a
model for assessing surgical difficulty.

4. • Outline the essential steps required to properly assess a
patient for third molar surgery.
• Influence the treatment plan.

5. History
• Discovery of X- rays in 1895, was a very important step in
treatment planning.
• According to Sonnabend (1973); Prof. Giesel of Berlin.
• Underwood (1901) : tilting of head sideways.
• Morton: intra-oral radiographs.

6. History
• For predicting difficulty:
• MacGregor : 1976 : radiographs
• Ten Bosch and Van Gool : 1977 : post-operative pain &
swelling.
• Winter’s contribution: 1926
• Made historical contribution to oral surgery
• Coined the terms exodontia and exodontist
• WAR lines of Winter

7. Preoperative assessment of Impacted
Teeth
• History
• Clinical examination
• Radiographic assessment

8. HISTORY
The first encounter with a patient , must establish a
working diagnosis, which always begins with a verbal
history from the patient

9. 1. Case history
1. Statistics of the patient : age ,sex
2. Chief presenting complaint
3. History of presenting complaint
4. Physical status
5. Medical history
6. Social history

10. Chief presenting complaint
• Main concern.
• Pain : subjective phenomenon.
• Detailed history : site, nature, duration & extent of pain
• Determine the cause & pathology.
• Other presenting problems:
- Localized swelling
- Limited mouth opening
- Discharge or foul taste in mouth

11. History of presenting complaint
• Background information : cause & nature of condition.
• Questions :
- When was the problem first noticed by the patient?
- What are the agrreviating & relieving factors?
- Any contributing factors ?
- What is the natural course of chief complaint?
- Was any treatment taken in past?

12. Medical history
• A medical history allows proper precautionary measures
to be taken to ensure patient safety.
• Impractical for clinician to delve into a detailed medical &
system history for all patients.
• Brief adequate medical questionnaire .

14. Medical disorders
1. Pregnancy
2. Cardiovascular diseases
3. Bleeding disorders
4. Respiratory disease
5. Endocrine disorders
6. Liver disease
7. AIDS
8. Prosthetic joint replacement
9. Head & neck radiotherapy.

15. Precautionary measures
• Further investigations e.g: clotting screening
• Alteration of patient’s current medication
• Pre-operative medication:
- Antibiotic cover
- Steroid cover
- Oral sedation
• Selection of anesthetic
• Post-operative medications
• To anticipate & adequately prepare for potential medical
emergency

16. Social history
• Social habits & practices
• Smoking history
• Alcohol intake
• Pregnancy status
• History of IV drug abuse

17. CLINICAL EXAMINATION
1. Extra – oral
2. Intra - oral

18. Examination
1. Inspection
2. Palpation
3. Percussion
4. Auscultation

19. Extra- oral examination
• 1. Inspection :
• General appearance
• Facial appearance
- swelling
- skin colour & texture
• Trismus
• Mouth opening

20. • 2. Palpation :
• Neck lumps : lymph node swellings
• Gross facial swelling : hot/ fluctuant : abcess?
• Skin colour & texture : firm/ soft , tender ?
• Paresthesia

21. Intra- oral examination
• 1. Inspection:
• Tongue : size, degree of mobility, colour & texture
• Oral mucosa : colour, texture, ulcers, lumps.
- Palate
- Cheeks
- Labial mucosa
- Floor of mouth
• Alveolar ridges & gingiva : colour, texture, recession,
swelling

22. Inspection
• Teeth in general:
- Number & position of teeth
- Large restorations
- Crowns
- Gross carious lesions
- Cracked or missing cusps
- Signs of grinding or severe attrition
- Occlusal relationship
- Condition of 1st & 2nd molar : periodontal

23. Inspection
• Third molars:
- Presence & degree of eruption in mouth.
- Functionality with opposing teeth
- Status of surrounding gingiva or overlying operculum
- Caries
- Crowns or large overhaning restorations in adjacent 2nd
molar.
- Space present between 2nd molar & ascending ramus

24. • 2. Palpation:
• Soft tissues
- Tenderness
- Flexibility
- Consistency & fluctuancy of any swelling.
• Third molars :
- Mobility
- Interproximal carious lesions
- Periodontal pocketing of adjacent 2nd molars
- Pus discharge under the inflamed operculum

25. • 3. Percussion :
• Tender on percussion
• Sound of tapping

26. RADIOGRAPHIC
EXAMINATION

27. Radiographs
• Intra oral radiographs
• IOPA
• Occlusal
• Extraoral radiographs
• OPG
• Lateral cephalometric
• Digital imaging
• CT
• CBCT
• Localization techniques:
• -Buccal object rule (SLOB)
• - Magnification
• -CBCT(3D)

28. IOPAR
Standard IOPA should include :
• Whole 3rd molar,
• Investing bony tissue,
• Inferior dental canal
• Adjacent molar teeth
• Clear superimposition the
buccal & lingual cusps of 2nd
molar : in both vertical &
horizontal planes.

29. Positioning of periapical film packet and angulation of central
ray in an average case.
Angulation of the central ray when viewed from the front-the
central ray (red arrow) is parallel with the transverse occlusal
plane (green line) which is usually at an angle of 3° to 4° above
the horizontal plane (blue dotted line)

30. In a poor film with incorrect angulation, the ‘enamel cap’
will be absent and there will be overlapping of contact
points of molars.
This occurs when the central ray is not parallel to the
transverse occlusal plane and if the central ray does not
pass at right angles to the film in the horizontal plane.

31. Occlusal film
• Bucco- lingual relationship.
• Demonstrates the exact position of the crown of the tooth
& the shape of laterally deviated roots.

32. Lateral oblique radiographs
• The practical value of xray:
a. Satisfactory substitute when
IOPAR cannot be taken.
b. To provide supplementary
record with additional
information to that obtained
by intra oral views.

33. c. Vertical depth of mandible.
d. Amount of bone below a deeply buried 3rd molar
e. Presence of double impactions
f. Etopic teeth
g. Associated abnormalities, existing pathologies in vicinity
of 3rd molar

34. OPG
• Recently due to easy availability , OPG has replaced the
lateral oblique view of mandible.
• All the information available from a lateral oblique view
can be had from OPG with less distortion .
• Routine use of OPG is an important advance in the
accurate localization of impacted teeth

35. • Advantages:
- All 3rd molars can be seen.
- Radiation dose is equivalent to 4 IOPA.
• Disadvantages :
- The use of intensifying screens entail a loss of image
detail when compared to IOPA

36. CBCT
• Cone beam computed tomography
• Provides 3- dimensional view of the 3rd molar
• Nerve can be traced.
• Can be used in selected cases.
• Disadvantage :
• Expensive and complicated for daily diagnostic problems.

37. Comparision of CBCT and panaromic radiographs.
• According to Ghaeminia et al :
CBCT contributed to better & optimal risk assessment
when compared to panaromic radiograph.
This, also influenced the surgical planning.
• According to Matzen et al :
• CBCT influenced the treatment plan for 12 % of cases.
• It reflected the relationship of canal with 3rd molar root.

38. Multimodal radiography
• Recently, Soredex (Finland) introduced a multimodal
radiography system called Scanora
• It combines the principles of narrow beam radiography &
Spiral tomography.
• Technique:
• Multiprojection narrow beam technique, which allows
stereoscopic views of a region.
• Projection angles are shifted 4 in horizontal & vertical
direction.

39. Other imaging techniques:
• Xeroradiography
• Dentascans
• Intra-oral cameras
• Magnetic resonance imaging

40. RADIOGRAPHIC
INTERPRETATION

41. Interpretation
1. Access
2. Position & depth (WAR lines)
3. Inclination : obliquity
4. Root pattern
5. Shape of crown
6. Texture of investing bone
7. Position and root pattern of second molar
8. Inferior alveolar canal
9. Follicle
10. Pathologies

42. 1. Access
Ease of access is determined by :
The inclination of the radio- opaque line cast by external
oblique ridge.
• External oblique ridge –
• vertical & ant. to third molar – easier
• Oblique/ horizontal & post. to third molar – difficult

43. 2. Position and depth
• George Winter.
• Three imaginary lines are drawn on a standard
radiograph.
1. White line
2. Amber line
3. Red line

44. White line
• Line drawn along the occlusal
surfaces of the erupted
mandibular molars , and extends
posteriorly over the third molar
region.
• Indicates the axial inclination .
• Indicates the depth .

45. Amber line
• Line drawn from the surface
of the bone , lying distally to
the third molar to the crest of
the interdental septum
between 1st – 2nd molar.
• Indicates the amount of bone
to be removed.

46. Red line
• Perpendicular line dropped from amber line to an
imaginary point of application for an elevator.
• Indicates the depth

47. • Red line <5mm: extraction - easy, there after every 1mm increase in depth;
increases the difficulty 3 folds &
• if it is >9mm then plan the surgery under GA.
• As a general rule DA teeth are more difficult than MA impaction of similar
depth & root pattern

48. 3. Obliquity of tooth
• Obliquity : The portion of the tooth nearest to the packet
film is always more sharply defined & more radio- opaque.
• Buccal obliquity: if apices are more sharply defined .
• Lingual obliquity : if the crown is more sharply defined.
• Lingual obliquity: more common

49. 4. Root pattern
• Affects both the line of withdrawal of teeth and decision
concerning which point for application of elevator.
• Radiograph must be carefully examined with reference
with the following factors :
• Fused or separate roots
• Number of roots
• Hypercementosis

50. • Configuration of the roots
• If curved, is curvature favorable or unfavorable ?
• Long and slender or short and stout roots.
• Convergent or divergent
• Proximity to inferior alveolar canal

51. Shape of crown
• Crown & cusp shape are of special importance
• When,
Line of withdrawal of the 3rd molar is completely obstructed
by the presence of a part of the 2nd molar : tooth impaction.
If the cusps of 3rd molar are superimposed upon the distal
surface of the 2nd molars in radiograph: sectioning
Large square shape crowns: more difficult.

52. Texture of investing bone
• If cancellous bone space are large and bone structure
enclosing the tooth is fine: elastic bone: easier
• If spaces are small, bone shadow is dense: sclerotic
bone: difficult
• Finer bone is easy to cut.

53. Root pattern of second molar
• If the 2nd molar has a simple conical root.
• Crown abutting into root of 2nd molar.
• Root resorption of 2nd molar.
• Care to be taken;
• It might get dislodged easily, while performing impaction.

54. Position of inferior alveolar canal
• An analysis of this relation is mandatory.
• In frontal plane;
mandibular canal is positioned buccal : 50- 75 % cases.
lingual : 6-7 %cases
inferiorly: 1-2 %cases

55. • In saggital plane;
• Avg. distance between root of 3rd molar & canal : 3mm
( inferior )
• Superior positioned : 10% cases.
• But, in recent studies using: 33% increase lingual& inferior
CBCT
• S.Sujaat et al, The Saudi dental journal (2014),26, 103- 107

56. Relationship of Root to Canal
Related but not involving the canal
Separated
Adjacent
Superimposed
Related to changes in the roots
Darkening of root
Dark and bifid root
Narrowing of root
Deflected root
Related with changes in the canal
Interruption of lines
Converging canal
Diverted canal

57. a. Related but not involving the canal
• Separated
• Adjacent
• Superimposed

58. b. Related to changes in the roots
• Darkening of root
• Dark and bifid root
• Narrowing of root
• Deflected root

59. c. Related with changes in the canal
• Interruption of lines
• Converging canal
• Diverted canal

60. BIFID & TRIFID MANDIBULAR CANALS
Most commonly occurs in females
During embryonic development, three separate canals fused
to form a single canal. Failure of this fusion results in bifid or
trifid canals – Chavez Lomeli

61. By NORTJE et al.,1977
Type I: Bilaterally single high mandibular canals: single high
canals either touching or within 2 mm of the apices of 1st and
2nd permanent molars.
Type II: Bilaterally single intermediate canals : single canals not
fulfilling the criteria for either high or low canals
Type III: Bilateral single low canals : single canals either touching
or within 2mm of the cortical plate of the lower border of the
mandible
Type IV: Variations including : asymmetry,duplications and
absence of mandibular canals
CLASSIFICATION OF MANDIBULAR CANAL

62. Size of follicular sac
• Larger follicular sac: easier : bone removal is less
• Non – existant / narrow follicular sac: difficult : requires
bone cutting.

63. ASSESSING THE DEGREE
OF SURGICAL DIFFICULTY

64. Age of patient
• Older patient : more difficulty : increased density &
decreased elasticity of bone with age: greater bone
removal: increased potential morbidity of the surgery.
• According to Susarla et al, older patients are a risk factor as
the bone is dense, hard & brittle.
• However, Akadiri et al , found no correlation with age.

65. Gender
• Mandibular 3rd molar impaction than maxillary 3rd molar
impaction.
• Females
• According to Nakagawa et al, the female gender is a risk
factor because of the mandible’s lesser bone thickness.

66. Age- and Gender-related Differences in
the Position of the Inferior Alveolar Nerve
• Regardless of age, females had significantly shorter
vertical distances from the IAN to the mesial and distal
apices.
• Females had shorter horizontal distances for total width of
mandibular bone at mesial and distal apices.
• The overall width of the mandibular bone decreased in
both genders from the 3rd–6th decade of life.
Age- and Gender-related Differences in the Position of the Inferior Alveolar Nerve by Using Cone Beam Computed
Tomography Jay D. Simonton, DDS, Bruno Azevedo, DDS, MS, William G. Schindler, DDS, MS,and Kenneth M.
Hargreaves, DDS, PhD

67. Physical status
• BMI : (weight [Kg] / height squared [m2])
• According to susarla et al, Akadiri et al , there exists a
correlation between BMI and surgical difficulty.
• Body weight is a function of body size & bone density.
• An obese patient will have thicker cheeks,
• Which will reduce accessibility to the tooth.
• However , Gbotolorun et al, found no such correlation.

68. Access
• Most important indicator of difficulty.
• Clinical:
• Restricted mouth opening
• Obese patients
• Reduced flexibility of soft tissues.
• Radiographical:
• External oblique ridge

69. Root pattern
a. The optimal time for removal of mandibular 3rd molars is
when the root is only 2/3rd developed.
b. In the early teenage years :no roots present & only the
crown is formed : surgical removal of mandibular 3rd
molar is complicated : absence of a stable purchase
point as the crown rolls freely around in its crypt.
c. In mature adults: root apices are fully developed :
degree of surgical difficulty increases with increase in
number of roots, complexity of root pattern & morphology

71. Degree of eruption
• Level of the tooth
• Level of occlusal plane—Pell and Gregory (occlusal plane
of third molar in relation to second molar)
• Partially erupted
• Unerupted.
• If unerupted:
• Soft tissue impaction
• Bony impaction

72. Degree of eruption
• An erupted tooth offers a purchase point for denrtal
elevators: without the need to raise flaps : easier
• An unerupted requires raising a flap for access & may
necessitate bone removal depending on degree of
impaction, increasing the complexity of surgery.

73. Depth of impaction
• Deeper : more bone removal in order to access the tooth:
increasing the :-
- morbidity,
- complexity
- operating time of surgery

74. Depth from point of elevation
• The length of a perpendicular line drawn from
distal amelocemental junction of 2nd molar distally
& the point of application of elevator.
• Point of elevator application:-
• Mesioangular & horizontal : mesial amelocemental
junction of 3rd molar
• Distoangular & vertical : bifurcation of 3rd molar

75. Angulation of tooth
• The least difficult teeth are those :
where the long axis of tooth is vertical ( or perpendicular)
with respect to the mandibular occlusal plane.
In some cases , however, vertical functioning teeth with
complex root patterns may prove quite difficult to remove.
• The tooth tilted mesially, distally or horizontal with respect
to mandibular occlusal plane : surgical difficulty increases:
• This is because the path of removal is obstructed either by
the 2nd molar or external oblique ridge.
• George dimitroulis : Handbook of third molar surgery

76. Angulation of tooth
• Mesioangular : easiest
• Distoangular : complex
• Mesioangular > horizontal > vertical> distoangular
• Susarla et al, carvalho et al, Daugela et al.

77. Retromolar space
• Available retromolar space—
• Pell and Gregory (distance between distal-most point of
second molar crown and anterior-most point of ascending
ramus)
• Small : less accessibility; more difficult
• Distal tiliting of 2nd molar :decreases accessibility

78. Periodontal tissues
• If the 2nd molar attached gingiva is : difficulty to suture
thin & sparse
• If the quality & quantity of the soft tissue are questionable:
Plan a longer incision that does not encroach on the
distobuccal line angle of the 2nd molar’s gingival attachment.

80. Impacted maxillary third molar
• Removal of an impacted maxillary third molar is difficult
because of :
1. Insufficient visualization of the area
2. Limited access
3. Maxillary sinus
4. Maxillary tuberosity fracture

81. Difficulty factors specific to maxillary third
molar
• Maxillary sinus:
- Roots are in intimate contact
- Tooth may form the posterior wall of sinus
- sinusitis
- oroantral communication
• Maxillary tuberosity fracture
- Dense , non elastic bone
- Large maxillary sinus
- Divergent roots
- Mesioangular impactions
- Excessive force

82. Maxillary sinus
• Maxillary sinus perforation occurs occasionally during
extraction of maxillary impacted tooth,
• And sometimes it may cause oro – antral communication.
• Close proximity of the 3rd molar root to maxillary molar :
increase difficulty

83. •

84. • The chances of creating an oro- antral fistula in patient
less than 15 years are lesser than in adults : due to
incomplete development of sinus.
• The distance between apical end of maxillary posterior
teeth and floor of sinus is approximately 1 - 1.2 cm.
• In some cases this gap may be even lesser : caution to be
executed.

85. Difficulty assessment of maxillary cuspids
• Based on determination of position:
- Labial ( easy )
- Palatal ( difficult) / middle ( difficult )
- potential damage to adjacent teeth
- potential periodontal deficits due to bone removal

89. HOW TO PREDICT THE DIFFICULTY
Various indices

90. Difficulty Assessment
INTERPRETATION:
•Relatively difficult: 3-4
•Moderately difficult: 5-7
•Very Difficult : 7-10
•Class I 1
•Class II 2
•Class III 3
•Mesioangular 1
•Horizontal 2
•Vertical 3
•Distoangular 4
•Position A 1
•Position B 2
• Position C 3
Pederson’s difficulty scale:

91. Modified parant scale

92. Wharfe’s Assessment
W- War lines
H- Height of the mandible
A- Angulation of 2nd molar
R- Root shape
F- Follicle
E- Path of exit

94. Height of the mandible:

98. J Oral Maxillofac Surg 72: 1644-1646, 2014

99. SUMMARY

100. Factors that Make Surgery Less Difficult:
• Good access for instrumentation
• Young ,male patients
• Mesio-angular impaction
• Class 1 ramus
• Position A depth
• Roots 1/3 – 2/3 formed (present in the younger patient)
• Fused conical roots
• Wide periodontal ligament (present in the younger patient)
• Elastic bone (present in the younger patient)
• Separated from IDN
• Soft tissue impaction

101. Factors that Make Surgery More Difficult:
• Obese patients with poor flexibility of cheeks : poor accessibility
• Old, female patients
• Disto-angular impaction
• Class 3 ramus
• Position C depth
• Long thin roots (present in the older patient)
• Divergent curved roots
• Narrow periodontal ligament (present in the older patient)
• Dense, inelastic bone (present in the older patient)
• Contact with 2nd molar
• Close to IDN
• Complete bony impaction

102. References
• Handbook of third molar surgery : George dimitroulis
• Principles of oral surgery: Moore & Gillbe
• The impacted lower wisdom tooth: MacGregor
• The impacted wisdom tooth : H.C.Killey
• Impacted teeth : W.H Archer
• Textbook and colour atlas of tooth impactions:
Andreasen.J.O
• Mandibular third molar impactions: Review of literature
and a proposal of classification: gintaras juodzbalyz and
Daugela. Journal of oral and maxillofacial
surgery,vol.4,june2013

103. • Risk factors for third molar extraction difficulty:
Srinivas.M.Susarla, Thomas Dodson. Journal of oral and
maxillofacial surgery 62, 2004
• Evaluation of the surgical difficulty in lower third molar
extraction : Jose Barreiro – Torres, Lucia Lago- Mendez:
medicina oral Nov 2010.
• Assessment of factors associated with surgical difficulty
during removal of impacted lower third molars : Ricardo
Wathson Carvalho, Belmiro Cavalcanti : J Oral Maxillofac
Surg : 2011

104. Local third molar inspection
• Inspection & palpation of mucosal tissues overlying the
site.
• Indicates ,if the crown is covered completely with bone or
mucosa.
• Supra position or malpositioning of the maxillary 3rd & 2nd
molar:
produce impinging trauma to the soft tissue overlying the
mandibular 3rd molar , will exacerbate the pericoronitis.

105. THANK YOU