The document discusses the definition, causes, and types of impacted teeth, emphasizing the importance of timely surgical interventions to prevent potential complications. It also outlines various treatment methods, including removal, coronectomy, and surgical exposure for impacted canines. Additionally, the document addresses the anatomical considerations and potential risks associated with the surgical management of impacted teeth, particularly the third molars.

2. Dr. Ahmed M. Adawy
Professor Emeritus, Dep. Oral & Maxillofacial Surg.
Former Dean, Faculty of Dental Medicine
Al-Azhar University

3. An impacted tooth can be defined as one which
does not erupt into its proper position in the
dental arch in the expected time frame,
instead staying below the gingival line (1).
Alternatively, impacted teeth have been defined
as those which are prevented from erupting into
their proper positions by a physical barrier
within their path (2)

4. The most commonly cited etiology for the impaction
of teeth is the lack of space in the dental arch into
which the tooth can erupt . Other causes cited for
the lack of space in the dental arch include premature
loss of the deciduous teeth, supernumerary teeth,
retention of the deciduous teeth, malposition of the
tooth crypt, infections, and tumors. Related to a lack
of space, is the possibility that teeth are becoming
impacted because of a hereditary disproportion
between the size of the teeth and the size of the
maxilla or mandible
(2)
(3)

5. Odntoma preventing eruption and causing impaction

6. Etiology of impaction, supernumerary teeth

7. As for the general factors, the most common
syndrome for tooth impaction is cleidocranial
dysplasia . Cleidocranial dysplasia is a rare inherited
form of skeletal dysplasia, and the most obvious
dental abnormality of the disease is prolonged
retention of deciduous teeth with failure in the
eruption of permanent teeth(4)

8. Multiple impactions in clediocranial dysplasia

9.  The lower third molar
 The upper third molar
 The upper canine
 The lower premolar
 The lower canine
 The upper premolar
 The upper central incisors
 The upper lateral incisors
 Upper and lower first molars are rarely impacted

10. Impactions are categorized by three variables: depth,
angulation, and available space. The depth of impaction
refer to where the cementoenamel junction of the tooth in
question lies in relation to the alveolar bone . Thus,
complete impaction can be described where the tooth is
entirely encased in bone (Level C) and partial impaction
where any part of the cementoenamel junction is below
the alveolar bone (Level B). The final state for a tooth is
complete eruption, where the cementoenamel junction is
completely above the alveolar bone (Level A)
(5)

11. Level (C)
Level (B)
Level (A)

12. In some instances, however, it is possible for the
cementoenamel junction to completely breach the alveolar
bone without the occlusal surface of the tooth breaking the
gingival line. In this case, the tooth is referred to as being
impacted in soft tissue, rather than partially or completely
in bone, Alternatively, it has been found that the most
common degree of impaction for third molar is partial
impaction, followed by complete eruption, complete
impaction, and lastly soft tissue impaction(5)

13. Soft tissue impaction
Partial bony impaction
Full (Complete) bony impaction

14. The angulation was assessed by measuring the angle
formed between the long axis of the impacted tooth
relative to the long axis of the teeth adjacent to it.
Different angulations of impaction are present:
Mesioangular,
Distoangular,
Horizontal,
Vertical, and
Bucco-Lingual angular
Mesioangular impaction is the most common type in
the third molar, followed by horizontal, distoangular,
vertical, and lastly buccoangular and linguoangular(5)

15. Mesioangular
Distoangular

16. Vertical

17. Horizontal
Bucco-lingual

18. According to the relation of the impacted mandibular
third molar to the anterior border of ramus, impaction
could be placed in one of class I or II or III .
Class I 3rd molar impaction: Situated anterior to the
anterior border of the ramus.
Class II 3rd molar impaction: Crown ½ covered by the
anterior border of the ramus.
Class III 3rd molar impaction: Crown fully covered by
the anterior border of the ramus
(6)

19. Class I - adequate room to erupt
Class II - one half covered
Class III- completely embedded

20. All impacted teeth are potentially pathologic. Lesions that
may be secondary to or associated with impacted teeth
include, but are not limited to, acute and chronic
inflammation or infection, resorption phenomenon,
carious lesions including those of adjacent teeth, cystic or
neoplastic disease, Pain of unexplained origin and
displacement or destruction of adjacent hard tissue
structures including teeth and bone. Pathologic conditions
are generally more common with age(7)

21. Pericoronitis: It is inflammation of soft tissues around
the crown of partially erupted or unerupted third
molar. It is a frequent emergency among 18-25 years
old patients
.

22. Dental caries and damage of adjacent teeth
Periodontal complications arising from food trapped
between the second and partially erupted third molar
resulting in deep periodontal pocket

23. Fracture: impacted teeth are weakening factors that may
cause fracture

24. Development of pathological conditions such as cystic
lesion and / or neoplastic disease

25. Diagnosis should be based on patient complaint, history,
clinical and radiographic evaluations. Periapical
radiographs have been used for many years to assess the
jaws during impacted teeth surgery. The most commonly
accepted imaging modality is the panoramic radiograph.
Nevertheless, the biggest concern of panoramic radiograph
is that mandibular canal could not be clearly identified in
the third molar region. Cone beam computed tomography
have been advocated as method of choice when there is
need to have a three dimensional view of the impacted
tooth and adjacent anatomical structures(8)

26. Cone beam computed tomography, localization of impacted tooth

27. The American Association of Oral and Maxillofacial
Surgeons recognizes the existence of scientific
evidence stating that impacted teeth represent a
potentially pathologic entity and that surgical
management is the treatment of choice . Whenever
possible, treatment should be provided before the
pathology has adversely affected the patient’s oral
and/or systemic health
(9)

28. To give patients the advantages of rapid healing and the
lowest incidence of morbidity, impacted teeth should be
treated as soon as it is apparent that they will not properly
erupt and occlude within the oral cavity. Treatment of
impacted teeth at an early age is associated with a
decreased incidence of morbidity. Treatment at an older
age carries an increase in the incidence and severity of
intraoperative and postoperative problems, a longer and
more severe period of postoperative recovery and greater
anesthetic risk

29. Treatment may include surgical removal,
coronectomy, surgical exposure, transplantation or
long-term observation of the impacted tooth. When
removal of an impacted tooth is indicated, it is
surgically prudent and cost beneficial that other
impacted teeth be considered for treatment at the
same surgical session. This reduces the need for
additional anesthetic and surgical procedures

30. Contraindications to the removal of impacted teeth
usually involve compromise in the patient’s physical
or medical status, extremes of age and the probability
of excessive damage to adjacent structures. The
decision to maintain an impacted tooth should be
based on valid evidence and expectations. In these
cases, long-term clinical and radiographic observation
is necessary and the patient must be informed of the
risks and benefits of surgical intervention versus
maintenance of the tooth and long-term observation

31. The surgical approach requires the elevation of a wide
mucoperiosteal flap for accessibility, overlying bone
must be removed for exposure, exposed teeth may be
sectioned, sectioned teeth are delivered, and finally the
wound must be closed. Tooth depth, angulation and
root morphology are the most consistent determinants
of extraction difficulty.
The surgical procedure is usually performed under local
anaesthesia. Infiltration anaesthesia placed in the area
overlying third molar impactions is used in addition to
block anaesthesia

32. Accessibility is a key issue in removal of impacted teeth.
The incision most commonly used is an envelope flap that
extends from the mesial of the first molar to the ramus with
lateral divergence of the posterior extension to avoid lingual
nerve injury. An alternative incision is a three cornered flap.
With this flap an anterior vertical releasing incision at the
distal aspect of the first or second molar is made depending
on the depth of impaction. The former is utilized in deep
impaction, while the latter is recommended in soft tissue
impaction. In either flap design the incision must be full
thickness

33. Flap design for impaction surgery
Envelope flap
Triangular flap

34. A hand piece with adequate speed and torque is used to
remove bone from the occlusal aspect of the tooth. Buccal
and distal bone removal is performed down to the cervical
line of the impaction

35. When sufficient access is obtained, the need for
sectioning of an impacted tooth can be determined.
After adequate bone has been removed and the tooth
is sectioned into manageable segments, the tooth is
delivered with elevators. Excessive force can result in
unfavorable root fracture, buccal or lingual bone loss,
damage to the adjacent second molar, or even fracture
of the mandible

36. Fracture of adjacent 2nd molar
Fracture mandible

37. Following tooth removal, the socket must be debrided
of all particulate bone and remaining tooth pieces. A
bone file, or bur can be used to smooth any sharp or
rough edges of bone. All follicular fragments should
be removed with a curette and mosquito hemostat

38. Primary closure of the wound sites is recommended.
Some surgeons are proponents of tight suturing to
assist in hemostasis, whereas other surgeons believe
that loose suturing leads to less edema and allows for
drainage of the wound

39. Mesioangular Vertical

40. Horizontal Distoangular

41. In general the proximity of the mandibular third molar to
the mandibular canal is considered a risk factor for
damage to the inferior alveolar nerve. Furthermore, it has
been demonstrated that the incidence of such complication
correlated with the absence of cortication around the
mandibular canal. In an attempt to prevent this serious and
unpleasant iatrogenic complication, coronectomy was
developed as a relatively new preventive method to
decrease the incidence of inferior alveolar nerve injury
compared with the conventional total removal of the lower
third molar
(10)

42. Coronectomy is performed when contact between the
mandibular third molar apex and the inferior alveolar nerve
is suspected. The principle is to remove the crown of the
impacted tooth and to leave the roots behind. The efficacy
of coronectomy compared with conventional tooth
extraction has been recognized in recent years. It has been
noted that retained roots after coronectomy in the lower
third molars produce no complications in terms of
infection, pain, or the development of pathologies within
the first 3 years(11)

43. A. Coronectomy of an impacted 3rd molar with nerve involvement
B. One year later shows bone formation as well as root migration

45. The classification systems of impacted maxillary third
molar are essentially the as for mandibular one. The close
relationship of the impacted tooth to the maxillary sinus
proposed additional classification:
1. Sinus approximation (SA)- no bone or thin bony
partition present between impacted maxillary third molar
and the floor of the maxillary sinus.
2. No sinus approximation (NSA)- 2 mm or more bone is
present between the sinus floor and the impacted maxillary
third molar

46. Generally speaking, with regard to difficulty, the same
angle of impaction yields the opposite degree of
difficulty in the maxilla when compared to the
mandible. Mesioangular impactions pose a greater
challenge compared with distoangular impactions in
the maxilla, whereas in the mandible, the situation is
reversed. However, when compared with mandibular
impacted third molars, maxillary procedures tend to
be more straightforward

47. The aspect that complicates matters the most in
maxillary impactions is that visibility can be a greater
limiting factor. Frequently, another complicating
factor in this surgery is the coronoid process of the
mandible. As the mouth is opened, it translates
anteriorly and often comes to lie buccally opposite to
the impacted maxillary third molar

48. Envelope and triangular flaps are also used for
maxillary surgery. The buccal bone in the maxilla is
less dense than in the mandible; therefore, removal of
bone is often more conservative. In general, unlike
mandibular third molar surgery, impacted maxillary
teeth require bone removal only on the buccal and
occlusal aspects. It is rare to ever remove significant
distal bone

49. The presence of the maxillary sinus and tuberosity
should be recognized and care should be taken with
the forces directed superiorly or posteriorly. Tooth
sectioning is generally not required for maxillary third
molar surgery An attempt should be made to place the
elevator from the mesiobuccal and engage the tooth
from a point that will permit movement of the tooth in
a distobuccal and buccal direction

50. Among the per and postoperative complications
associated with maxillary third molar extraction, the
most commonly mentioned in oral surgery textbooks
are fractures of the maxillary tuberosity and accidental
displacements into the infratemporal fossa or
maxillary sinus . Excessive apical force during
use of elevators and incorrect surgical technique are
quoted as the most usual causes of these accidents
(6,12)

52. Canines contribute significantly in functional
occlusion and form the foundation of an esthetic
smile. So, any factor that interferes with the normal
development and eruption of canine has serious
consequences.
Ideal approach for the management of impacted
canine is interdisciplinary management comprises of a
team of an orthodontist, oral surgeon, and periodontist

53. Intervention at an early age (10-13 years) with
extraction of deciduous canine may help spontaneous
eruption of permanent canine. Removal of physical
barrier like a supernumerary tooth, Odntome, fibrous
bands, and tooth sac are helpful in tooth eruption.
Creation of sufficient space by maxillary expansion
and molar distalization improves the prognosis of
canine impaction

54. Surgically assisted orthodontic guidance is required
when a definitive diagnosis of impaction is
established, and possibilities of spontaneous eruption
are exhausted. It is considered after complete root
apex formation. Two different methods of surgical
exposure of impacted canine have evolved, one
method is commonly known as the open eruption
technique, and the other method is called the closed
eruption technique (13)

55. Open eruption involves the surgical excision of a
wedge-shaped section of the overlying palatal mucosa
after removal of the bone covering the ectopic canine.
A surgical or periodontal pack is then placed over the
exposed tooth for 7-10 days. After pack removal, a
bonded attachment is placed, and orthodontic traction
is commenced. This technique is mostly used for
palatally impacted canines

56. The technique of closed eruption usually involves raising
a large full thickness flap with a minimum degree of bone
removal to uncover the ectopic canine. An attachment or
bracket with a braided wire ligature connected to it is
bonded to the crown of the exposed canine during surgery.
The mucosa is then sutured back into place with the end of
the wire ligature extending into the mouth either through
the wound margin or through an incision placed in the
flap. Orthodontic traction is usually commenced soon after
the surgical exposure. This technique is mostly used for
labially impacted canines

57. Closed eruption technique

59. 1. Hattab FN., Abu Alhaija ES. Radiographic Evaluation of Mandibular Third
Molar Eruption. Oral Surg, Oral Med, Oral Path, Oral Radio, and Endo. 88:
285, 1999.
2. Farman A G. Tooth Eruption and Dental Impaction. Panoramic Radiology :
Seminars on Maxillofacial Imaging and Interpretation. A. G. Farman (ed).
New York, Springer. p 73-82, 2007
3. Eidelman D. "Fatigue on Rest" and Associated Symptoms (Headache,
Vertigo, Blurred Vision, Nausea, Tension and Irritability) Due to Locally
Asymptomatic, Unerupted, Impacted Teeth." Medical Hypotheses. 5: 339,
1979.
4. Becker A, Lustmann J, Shteyer A. Cleidocranial dysplasia: part 1- general
principles of the orthodontic and surgical treatment modality. Am J Orthod
Dentofacial Orthop. 111:28, 1997.
5. Quek, S L, et al. Pattern of Third Molar Impaction in a Singapore Chinese
Population: A Retrospective Radiographic Survey. Inter J Oral Maxillofac
Surg 32: 548, 2003.
6. Hupp, J.R. Principles of management of impacted teeth. In Hupp, J.R., Ellis
Ш, E. and Tucker, M.R. (eds.). Contemporary oral and maxillofacial surgery,
3rd.ed, Mosby Elsevier, St Louis, p 153-178, 2008.

60. 7. Koerner KR. The removal of impacted third molars. Principles and
procedures. Dent Clin North Am. 38: 255, 1994.
8. Boeddinghaus R, Whyte A: Current concepts in maxillofacial imaging.
Euro J Radio. 66:396, 2008.
9. The American Association of Oral and Maxillofacial Surgeons. The
Management of Impacted Third Molar Teeth, 2013.
10. Pogrel MA, Lee JS, Muff DF: Coronectomy: a technique to protect the
inferior alveolar nerve. J Oral Maxillofacial Surg 62: 1447, 2004.
11. Leung YY, Cheung LK. Coronectomy of the lower third molar is safe
within the first 3 years. J Oral Maxillofac Surg. 70: 1515, 2012.
12. Ness GM. Impacted teeth. In Miloro M, Ghali GE, Larsen PE, Waite
PD. (eds). Peterson’s Principles of Oral and Maxillofacial Surgery, 3rd.ed.
PMPH-USA, Shelton, Connecticut, p 97-121, 2012.
13. Biswas1 N, Soma Halder Biswas SH, Shahi AK. Maxillary Impacted
Canine: Diagnosis and Contemporary Ortho Surgical Management
Guidelines. Inter J Scientific Study. 3: 166, 2016.