Journal reading - Mouth Surgery - Clerkship Medical Student

1. MANDIBULAR THIRD MOLAR IMPACTION:
REVIEW OF LITERATURE AND A PROPOSAL
OF A CLASSIFICATION
Journal Reading
Aris Rahmanda (07120100091)
Faculty of Medicine,
Pelita Harapan University
Gintaras Juodzbalys, Povilas Daugela
JOURNAL OF ORAL & MAXILLOFACIAL RESEARCH 2013 (Apr-Jun)

2. ABSTRACT
Objective :
1. To review impacted mandibular third molar :
• Etiology
• Clinical anatomy
• Radiologic examination
• Surgical treatment
• Possible complication
2. To create new mandibular third molar impaction &
extraction difficulty degree classification based on
anatomical & radiological findings and literature review
result

3. ABSTRACT
Materials & Method
• Literature was selected through a search on
PuMed,Embase & Cochrane electronic database
Results
• In total 75 literature sources were obtained and reviewed
• New mandibular third molar impaction and extraction
difficulty degree classification based on anatomical and
radiologic findings and literature review results was
proposed
Conclusion
• The classification proposed is promising to be a helpful
tool for impacted tooth assessment as well as for planning
for surgical operation

4. INTRODUCTION
Definition of Impacted Tooth :
1. Mead [1954]
Impacted tooth as a tooth that is prevented from erupting
into position because of malposition, lack of space, or other
impediments
2. Later Peterson
Impacted teeth as those teeth that fails to erupt into the
dental arch within the expected time
3. Farman [2004]
Impacted teeth are those teeth that prevented from
eruption due to a physical barrier within the path of eruption

5. INTRODUCTION
• Elsey and Rock : Impaction of the third molar is occurring
in up to 73% of young adults in Europe.
• Generally, third molars have been found to erupt between
the ages of 17 and 21 years
• Third molar eruption time have been reported to vary with
races
• The average age for the eruption of mandibular third
molars in male is approximately 3 to 6 months ahead of
females

6. RESULTS
Aetiology :
1. Most popular theory is : insufficient development of the
retromolar space
2. Due to a decrease in the angulation of the mandible and
an increase in the angulation of the mandibular plane
3. Relation between the root angulation and impaction:
angulated roots were more common in impacted
mandibular third molars
4. Malposition of the tooth germ
5. Hereditary factors
6. Lack of sufficient eruption force for third molars
7. Theory of phylogenetic regression of the jaw size

7. RESULTS
Clinical Anatomy :
1. Mandibular third molar is situated at the distal end of the
body of the mandible where is connection with relatively
thin ramus
2. There is the region of weakness and the fracture can
occur if excessive force will be applied
3. The lingual nerve often lies close to the cortical plate
4. Close relationship of the canal with the roots can evoke
inferior alveolar nerve damage during the surgery

8. Sources : http://www.mccullochlaw.net/images/nerve_injury

9. RESULTS
Radiologic Examination :
• Important in imaging diagnosis for the proper surgical
operation planning
1. Long cone paralleling technique for taking periapical X-
ray is the technique of choice for the following reasons :
Reduction of radiation dose
Less magnification
True relationship between bone height & adjacent teeth
Cons : Mandibular canal could not be clearly identified in
the third molar region

10. RESULTS
Radiologic Examination :
2. Panoramic radiograph
Advantages :
• Broad coverage of oral structures
• Low radiation exposure (about 10% of a full-mouth
radiographs)
• Relatively inexpensive of the equipment
Disadvantages :
• Lower image resolution
• High distortion
• Presence of phantom images

11. RESULTS
Radiologic Examination :
3. Cone Beam Computed Tomography (CBCT)
• As method of choice than there is need to have a three
dimensional view of the mandibular third molar and
adjacent anatomical structures
• CBCT contributes to optimal risk assessment and, as a
consequence, to more adequate surgical planning,
compared with panoramic radiography

12. Sources :
1) X-ray Using Parellel Cone Technique
http://www.columbia.edu/itc/hs/dental/endo/client_edit/lectures/images/parallel.jpg
2) CBCT
http://drkhaledtarboush.weebly.com/uploads/2/0/8/3/2083266/2488250_orig.jpg

13. RESULTS
Indications for mandibular third molar extraction
According to the recommendations of National Institute of
Health (NIH) :
Both impacted and erupted mandibular third molars with
evidence of follicular enlargement should be removed
electively and that the associated soft tissue should be
submitted for microscopic examination
Impacted teeth with pericoronitis should also be extracted
electively
Third molars with non-restorable carious lesions and third
molars contributing to resorption of adjacent teeth

14. RESULTS
Indications for mandibular third molar extraction
Indication according to Koerner & Lytle :
1. Existing pathology or pain
2. Inflammation of the opposing soft tissue
3. Aberrant positions in which the tooth is oriented buccally
or lingually
4. Impacted third molars are affecting the stability of
orthodontic treatment.
5. Infection around the impaction
6. Dental caries and damage of adjacent teeth

15. RESULTS
Surgical extraction of Impacted Mandibular Third Molar
& Possible Complication
 There are two main apporaches, intraoral & extraoral
• Two intraoral approaches for surgical removal of impacted
mandibular third molars :
1. Through the sublingual space
2. Other buccally through the entire mandibular thickness
Through the entire mandibular thickness

16. RESULTS
Surgical extraction of Impacted Mandibular Third Molar &
Possible Complication
Complications related to mandibular third molar extraction can be
classified to intraoperative and postoperative :
1. Intraoperative complications are as follows :
a. Mandibular fracture
b. Damage of adjacent teeth,
c. tooth or tooth fragments displacement into soft tissues
d. Bleeding
e. Most serious and unpleasant iatrogenic complication is
inferior alveolar and/or lingual nerve injury and
neurosensory function disturbance (0.81-22% Cases)
2. Post-operaive complications are pain,sweeling, bruising &
trismus

17. RESULTS
Classifications and risk factors identification
Several classifications have been developed that are
assessing the difficulty of surgical procedure and helping to
create an optimal treatment plan, ex :
1. Winter’s line
2. Pell & Gregory’s scale
Classifying the inclinations and positions of the third molars
based on the relation among the dental longitudinal axis,
occlusal plane and ascending mandibular ramus

18. RESULTS
Classifications and risk factors identification
1. Chuang et al :
Level of impaction is associated with an increased risk of
inflammatory complications following third molar surgery.
2. Akadiri and Obiechina :
Wisdom tooth depth angulation and root morphology as the
most consistent determinants of extraction difficulty.
3. The risk of nerve injury is increasing with the depth of the
impacted mandibular wisdom teeth
4. Iatrogenic injury to the lingual nerve may happen during
surgery due to the anatomical proximity of the cortex
region of the molar to the nerve

19. RESULTS
Mandibular third molar impaction classification based
on anatomical and radiologic features
a. Classification helps clinician to determine the difficulty in
removal of the impacted tooth, to choose optimal
treatment and to avoid the majority of possible
complications
b. This classification describes wisdom tooth relation to the
adjacent anatomical structures: mandibular ramus,
second molar, alveolar crest, mandibular canal, and the
spatial position of the tooth
c. Wisdom tooth position assessment should be performed
clinically and using CBCT and panoramic radiographic
images.

20. RESULTS
Mandibular third molar impaction classification based
on anatomical and radiologic features
Proposed classification is determining mandibular third molar
mesiodistal position :
1. In relation to the second molar - M
2. Mandibular ramus - R
3. Apicocoronal position (in relation to the alveolar crest - A,
and the mandibular canal – C)
4. Buccolingual position (in relation to mandibular lingual
and buccal walls – B
5. Spatial tooth position - S.

22. Detailed explanation:
1. Crown is in contact below the equator to the coronal third of the second molar (M1)
2. Partially impacted in the ramus (R1)
3. Widest part of the crown (equator) is below the bone (A2),
4. Roots are contacting or penetrating the mandibular canal, wall of the mandibular
canal is unidentified (C2)
5. Tooth is located in the middle between lingual and buccal walls (B1)
6. Horizontal spatial position (S3)
Complicated extraction is anticipated (S3) and C2 value presumes moderate risk of
inferior alveolar nerve damage

24. CONCLUSION
1. There are selected only the most informative
parameters in presented herein classification
2. The classification proposed here based on anatomical
and radiological impacted mandibular third molar
features is promising to be a helpful tool for impacted
tooth assessment as well as for planning for surgical
operation
3. Further clinical studies should be conducted for new
classification validation and reliability evaluation.