Impaction is the cessation of eruption of a tooth caused by a physical barrier or ectopic positioning of a tooth.
unerupted tooth is a tooth lying within the jaw bone, entirely covered by soft tissue, and partially or completely covered by bone.
A partially erupted tooth is a tooth that has failed to erupt fully into a normal position
2. outline
• Introduction
• Causes of impaction
• Development of third mandibular molar
• Indications and contra-indications for removal of impacted 3rd
molars
• Classification of impacted 3rd molars
• Removal of 3rd molar surgically
• Conclusion
• References
3. introduction
• Impaction is the cessation of eruption of a tooth caused by a physical
barrier or ectopic positioning of a tooth.
• unerupted tooth is a tooth lying within the jaw bone, entirely
covered by soft tissue, and partially or completely covered by bone.
• A partially erupted tooth is a tooth that has failed to erupt fully into a
normal position
4. Frequency of impaction(incidence)
• Mandibular 3rdmolar- >Maxillary 3rd
molar->Maxillary canine->Mandibular
premolar-> Maxillary premolar-
>Mandible canine->Maxillary central
incisor->Maxillary later incisor
5. Why impaction
• Inadequate Space in the Dental Arch for Eruption
>can be explained by the following theories
- The phylogenic theory
>Due to evolution, the human jaw size is becoming smaller and smaller
>there may be no be room for the 3rd molar to emerge in the oral cavity
,since it is the last tooth to erupt
- Mendelian theory
>Based on genetic variations
> If the individual genetically receives a small jaw from one of the parents
and/or large teeth from the other parent, then impacted teeth can be seen,
because of ‘lack of space’.
6. Development of mand 3rd molar
• The mandibular third molar tooth germ is usually visible radiographically by
age 9 years
• cusp mineralization is completed at age 11 years
• tooth located within the anterior border of the ramus with its occlusal
surface facing anteriorly ,at the level of occlusal plane of erupted dentition
• Crown formation is complete at age of 14 years,
• Roots are approximately 50% formed by age 16 years.
• During this time the body of the mandible grows in length at the expense
of resorption of the anterior border of the ramus.
• Roots completed at age of 18 and by age of 24 years 95% full erupted
7. Development cont….
• During root formation there is change in orientation from straight
anterior inclination into straight vertical inclination
• These changes needs sufficient space, which if absent causes
impaction
8. Reasons for removing impacted 3rd molars
• Pericoronitis and pericoronal abscess
- This is the most common cause for extraction of mandibular third
(25 to 30%)
-Pericoronitis is commonly associated with distoangular and vertical
impaction.
- If improperly treated or left untreated infection may extent
posteriorly resulting in sub masseteric abscess
9. • Dental caries
- Incidence of caries of the 2nd molar or 3rd molar is about 15%
- high incidence is due to difficulty to perform oral hygiene measures
in the third molar and second molar areas
10. • Prevention of odontogenic cysts
-in impacted tooth ,the associated follicular sac is retained within the
bone
-follicular sac may undergo cystic degeneration to form dentigerous
cyst or keratocyst
-these cysts may attain large sizes if left untreated and cause facial
asymmetry
-ameloblastoma may arise from the epithelial lining of the
cycts(mural ameloblastoma)
11. • Prevention of root resorption
- impacted tooth causes sufficient pressure on the root of an
adjacent tooth to cause root resorption
-this process is not well understood , it appears to be similar to
resorption process during eruption
-primary teeth do undergo resorption to allow eruption of
permanent tooth
-Removal of impacted tooth may save the adjacent tooth through
cemental repair
12.
13. • Impacted tooth under dental prosthesis
-assessment to be done before planning for surgery
- superficial impacted teeth should be removed before prosthetic
appliance is constructed.
- because alveolar process slowly undergoes resorption
-tooth will come closer to the surface giving appearance of erupting
-denture may compress the soft tissues onto the impacted tooth which
is no longer covered by bone
-the result is ulceration and initiation of odontogenic infection
-if extraction is done after prosthesis has been made ,it will become non
functional an unattractive bse alveolar ridge may be so altered by extraction
14. • Prevention of jaw fractures
-Prophylactic removal of impacted third molars should be
considered for those engaged in contact games
- An impacted third molar presents an area of lowered resistance to
fracture
-Also presence of impacted tooth in the line of fracture may cause
increased complications in the treatment of fracture
15. • To facilitate orthognathic surgery
-In presurgical preparation for orthognathic surgery, removal of third
molars at the planned osteotomy must be done
-the removal brings better results eg in bilateral sagittal split osteotomies
(BSSO) can be better performed when third molars are not present at the
site of osteotomy.
-Third molars (both erupted and unerupted should be removed
preferably one year before the planned osteotomy to ensure the formation
of adequate bone
-Rigid fixation of the osteotomized segments needs adequate sound
bone to secure plates and screws
16. • Facilitation of orthodontic treatment
-Third molars can produce an anterior component of force leading to
crowding of mandibular incisors
- removal of third molars is recommended during or after
orthodontic treatment
- Some orthodontic approaches to a malocclusion might benefit
from the placement of retromolar implants to provide distal anchorage
-When this is planned, removal of impacted lower third molars is
necessary.
17. • Periodontal diseases
-Blakey et al (2002) reported that the prevalence of increased
periodontal probing depths (PD) in the third molar region is higher than
that is expected in asymptomatic third molars.
- They noted that in inceassesd PD –> 5 mm in the third molar
associates with gingivitis and periodontitis
- Increased periodontal probing depths and attachment loss leads to
increased periodontal pathogen colonization and increased levels of
inflammatory mediators which causes periodontal diseases
18. • Treatment of Pain of Unexplained Origin
-Occasionally, patients may complain of pain in the retromolar region
of the mandible for no obvious reasons.
-removal of third molar may result in resolution of pain
-but conditions such as myofacil pain dysfunctionsyndrome and
other pain disorders should be excluded
19. Contraindications of removal of 3rd molars
• extreme of ages
-The third molar tooth bud can be radiographically visualized by age 6
-Some surgeons think that removal of the tooth bud at age 7 to 9 can be
accomplished with minimal surgical morbidity
-However, it is not possible to predict accurately if the forming third molar will be
impacted
-early removal of third molars should be deferred until an accurate diagnosis of
impaction can be made
-Also it is contraindicated in advanced age because the bone becomes highly
calcified and therefore not flexible and unlikely to bend under the forces of tooth
extraction.
-so more bone must be surgically removed to displace the tooth from its socket.
20. -if impacted tooth is discovered at older age and with no periodontal
disease, caries or cystic degeneration,then its unlikely for these sequela
to occur
-so older pt (>35)shows no signs of disease and radiographyicaly
there is enough bone overlying is not removed
21. • Compromised medical status
-more often compromised medical status and advancing age go
hand in hand.
- If the impacted tooth is asymptomatic, its surgical removal must
be viewed as elective.
-in conditions such as immunocompromised ,cardiovascular or
respiratory serious illneses, coagulopathy surgery is to be avoided
22. • Probable excessive damage to surrounding structures
-it is advised to leave the tooth in the alveolar bone if its removal will
jeopardize adjacent nerves ,teeth , crowns bridges etc
-decision to not remove the impacted tooth should be weighed
against possible future complications
- for younger patients its wise to remove the impacted tooth while
taking great measures to avoid damage to adjacent structures
23. Classification of impacted mandibular 3rd
molars
• Angulation(winters classification)
-most commonly used system in relation to treatment plan
-uses a determination of the angulation of the long axis of the
impacted third molar with respect to the long axis of the adjacent
second molar
-it gives an initial useful evaluation of the difficulty of extractions
but is not sufficient by itself to define difficulty of molar removal fully.
-generally the least difficult impaction to remove is the
mesioangular, particularly when only partially impacted
25. b)Horizontal impaction
-uncommon and more difficult to remove than mesioangular
impaction.
- The crown of impacted tooth is usually adjacent to second molar and
it produces early periodontal disease
26. c)Vertical impaction
- Long axis of the impacted tooth is vertical
- second most common impaction and second most difficult to remove.
- Vertical impaction is frequently covered on its posterior aspect with
bone of anterior ramus of mandible.
27. d)Distal impaction
-uncommon and most difficult of the four types to remove
-Occlusal surface of distoangular impaction is usually embedded in
ramus of mandible and requires significant bone removal for extraction
28. • Relationship to anterior body of mandible
-aka pell and Gregory classification classes 1,2 and 3
-based on the amount of impacted tooth that is covered with the bone of
the mandibular ramus
a)Class I - Space between anterior border of ramus and distal side of 2nd
molar is enough to accommodate the mesiodistal diameter of the 3rd molar.
b)Class II - Space between distal aspect of 2nd molar and anterior border of
ramus is less than the mesiodistal diameter of 3rd molar and hence partial
buried in ramus.
C) Class III - 3rd molar is totally embedded in bone from ascending ramus
because of absolute lack of space.
29.
30. • Relationship to occlusal plane
-pell and Gregory classes A,B ad C
-The depth of the impacted tooth compared with the height of the
adjacent second molar
a)Class A
-Occlusal plane of impacted tooth is at same level as occlusal plane of
second molar
b)Class B
- Occlusal plane of impacted tooth is between occlusal plane and
cervical line of second molar.
33. PREOPERATIVE ASSESMENT
• CLINICAL EXAMINATION
-History taking
>chief complaint and HPI
>medical and dental history
-Extra oral and intraoral examination
• RADIOGRAPHIC ASSESSMENT
-complement the clinical examination by providing additional
information about the third molar, the related teeth and anatomical
features, and the surrounding bone
34. -periapical
-lateral view
-OPG(panoramic view )
• Radiographs will provide the following-
- Access
-Position and depth of impacted tooth
-Root pattern of impacted tooth
–Shape of crown
-Texture of investing bone
-Relation to inferior alveolar canal
-Position and root pattern of second molar
35. • Surgical removal(Kelsey Fry)
-Step 1: Reflection of adequate flap for accessibility
- Step 2: Removal of overlying bone
-Step 3: Sectioning of the tooth
-Step 4: Delivery of the sectioned tooth with elevator
- Step 5: Wound debridement and closure (suturing).
36. • Reflection of adequate flap for accessibility:
- Overlying tissue must be removed for accessibility and visibility
- mucoperiosteum flap is reflected for easy placement and stabilization of
instruments
a)Envelop flap
-The most commonly used
-incision extends from just posterior to the position of the impacted tooth
anteriorly to the level of the first molar.
- The posterior end of the incision is directed buccally along the external
oblique ridge.
- Its associated with fewer compications and healing is fast
37. b)Triangular flap
-if greater accessibility is required a releasing incision is made anterior
to the envelop flap to form a triangular flap
-It begins at a point approximately 6 mm down in the buccal sulcus and
then extended obliquely upwards to the gingival margin to a point at
the junction of the posterior and middle thirds of the second molar
38.
39. • Removal of overlying bone
- The bone covering the impacted tooth is removed
- Removal can be accomplished by bur or chisel and mallet or
combination of the two methods
- First of all, the bone covering the occlusal part is removed to expose
the tooth
- followed by removal of the Buccal aspect of the bone till the cervical
margin of the tooth
- Then bone between the tooth and the cortical bone should be
removed to provide better access. This process is known as 'Ditching'.
40. -The depth of bone removal depends on depth of impaction
,morphology of roots and angulation of tooth
-lingual bone is not removed to prevent severe of the lingual nerve
41. • Sectioning of the tooth;
- Sectioning indicated if the tooth has been sufficiently exposed,and
still resistant to the use of elevator
- Reduces operating time and avoids removal of excessive amount of
bone
- Sectioning of tooth will depend on the angulations of tooth , depth
of impaction and root morphology
- Bur is used to section the tooth ,straight elevator is used to deliver
the tooth.
42. • Mesioangular impaction:
-section the distal part from the tooth and remove it
-followed by the mesial portion
• Horizontal impaction:
The distal portion of the crown is sectioned first then the distal part of
the root, followed by the mesial portion of the tooth
43. • Vertical impaction
- The tooth is sectioned into mesial and distal .
- Mesial half is removed followed by the distal half
• Distoangular impaction
- The crown of the tooth is removed first, followed by either of the
roots
44.
45.
46.
47. • Delivery of the sectioned tooth with elevator
-The sectioned tooth is removed from the bone by using elevator
- Excess force should not be applied by the elevator but just enough to
lift the tooth
- Most commonly used elevators are
• Straight elevator
• Paired Cryer elevator
• Crane pick elevator
48. • Debridement of wound and wound closure
- Debridement of the wound is done by:
> Removing the bone chip and debris from the wound
> Periapical curettage
> smoothening of the sharp bony edges using bone file
>Irrigating with normal saline
>Control of bleeding
- Wound closure done by placing 3-4 sutures for envelop flap and
additional 1 suture for triangular flap
49. Postoperative management
• Post operative instruction should be given
• Medications
>antipain and antiflamatory -NSAIDS and steroids
>antibiotics-metronidazole and penicilins or erythromycin for
penicillin allergic pts
• suture removal
>done after 5-7 days
50. conclusion
• The surgical removal of third molars has been, and still is, the most
frequent operation performed by oral and maxillofacial surgeons both
in private practice and in hospital setting
• Extensive training, skill, and experience are necessary to perform this
procedure with minimal trauma
• When the surgeon is untrained and/or inexperienced, the incidence
of complications rises significantly
• Determining the need for removal of asymptomatic teeth is made
based on clinical experience and professional judgment.
51. references
• Petersons PRINCIPLES OF ORAL AND MAXILLOFACIAL SURGERY
Second edition chapter 8 pg 140
• ORAL AND MAXILLOFACIAL SURGERY by lars Andersson pg 235
• COTEMPORARY ORAL AND MAXILLOFACIAL SURGERY 5TH EDITION PG
180
• PRACTICAL GUIDE TO THE MANAGEMENT OF IMPATED TEETH by K
George
• A CONCISE TEXTBOOK OF ORAL AND MAXILLOFACIAL SURGERY PG
127
