“Definition of
Impacted tooth”
An impacted tooth is any tooth that is prevented from
reaching its normal position in the mouth by tissue, bone, or another tooth.
Of the surgical
procedures performed in the oral cavity, the removal of impacted and
semi-impacted teeth is the most common. The extraction of these teeth,
depending on their localization, may prove to be relatively easy or extremely
difficult and laborious. Regardless of the degree of difficulty of the surgical
procedure though, its success primarily depends on correct preoperative
evaluation and planning, as well as on the treatment of complications that may
arise during the procedure, or the management of complications that may present
after the surgical procedure. For these reasons, a medical history, clinical
examination of the patient, and radiographic evaluation of the area surrounding
the impacted tooth are deemed necessary.
Indications for
removal of impacted tooth
Specialists have divergent points of view concerning the necessity to
extract impacted teeth. Certain people suggest that the removal of impacted teeth
is necessary as soon as their presence is confirmed, which is usually by
chance. They even believe that it must be done as soon as possible, as long as
there is no possibility that the impacted tooth may be brought into alignment
in the dental arch using a combination of orthodontic and surgical techniques. On
the other hand, others suggest that the preventive removal of asymptomatic
impacted teeth, besides subjecting the patient to undue discomfort, entails the
risk of causing serious local complications (e.g., nerve damage, displacement
of the tooth into the maxillary sinus, fracture of the maxillary tuberosity,
loss of support of adjacent teeth, etc.). As far as impacted teeth that have
already caused problems are concerned,everyone agrees that they should
be removed, regardless of the degree of difficulty of the surgical procedure. The
most common of these problems are now given.
Pericoronitis in
a semi-impacted mandibular third molar. Diagrammatic illustration showing inflammation
under the operculum and distal to the crown of the tooth.
Clinical
photograph. Characteristic swelling of the operculum due to constant biting
from the antagonist
Localized
or Generalized Neuralgias of the Head(Prevention of pain of unexplained origin.
Impacted teeth may be
responsible for a variety of symptoms related to headaches and various types of
neuralgias. If this is the case, the pain may be due to pressure exerted by the
impacted tooth where it comes into contact with many nerve endings. Many people
suggest that the symptoms may subside after the removal of the offending tooth,
which basically involves ectopic impacted teeth.
Pericoronitis.
This is an acute
infection of the soft tissues covering the semi-impacted tooth and the
associated follicle. This condition may be due to injury of the operculum (soft
tissues covering the tooth) by the antagonist third molar or because of
entrapment of food under the operculum, resulting in bacterial invasion and
infection of the area. After inflammation occurs, it remains permanent and
causes acute episodes from time to time. It presents as severe pain in the
region of the affected tooth,which radiates to the ear, temporomandibular
joint, and posterior submandibular region. Trismus, difficulty in swallowing, submandibular
lymphadenitis, rubor, and edema of the operculum are also noted. A
characteristic of pericoronitis is that when pressure is applied to the
operculum, severe pain and discharge of pus are observed. Acute pericoronitis
is often responsible for the spread of infection to various regions of the neck
and facial area.
Production
of Caries.
Entrapment of food
particles and bad hygiene, due to the presence of the semi-impacted tooth, may
cause caries at the distal surface of the second molar, as well as on the crown
of the impacted tooth itself.
Decreased
Bone Support of Second Molar.
The well-timed
extraction of a semi-impacted tooth presenting a periodontal pocket ensures the
avoidance of resorption of the distal bone aspect of the second molar, which
would result in a decrease of its support.
Obstruction
of Placement of a Partial or Complete Denture.
The impacted teeth of
edentulous patients can erupt towards the residual alveolar ridge, creating problems
when applying a prosthesis. The localization of the tooth is often observed
after its communication with the oral cavity and the presence of pain and
edema.
Obstruction
of the Normal Eruption of Permanent Teeth.
Impacted teeth and
supernumerary teeth often hinder the normal eruption of permanent teeth, creating
functional and esthetic problems.
Provoking
or Aggravating Orthodontic Problems.
Lack of roomin the
arch is possibly themost common indication for extraction, primarily of
impacted and semi-impacted third molars of the maxilla and mandible.
Participation
in the Development of Various Pathologic Conditions.
The coexistence of an
impacted tooth and various pathologic conditions is not an uncommon phenomenon.
Often cystic lesions develop around the crown of the tooth and are depicted on
the radiograph as different-sized radiolucencies. These cysts may be large and may
displace the impacted tooth to any position in the jaw. Whenthe presence of
such osteolytic lesions is verified radiographically, they must be removed
together with the associated impacted tooth.
Destruction
of Adjacent Teeth Due to Resorption of Roots.
Resorption of the
roots of adjacent teeth is another undesirable situation that may be caused by the
impacted tooth; the effect isbrought about through pressure. This case
primarily involves the posterior teeth of the maxilla and mandible. It begins
with resorption of the distal root and, eventually, may totally destroy the tooth.
The resorption of rootsmay also be observed in other areas of the dental arch
and may involve dental surfaces other than those mentioned above. Having
mentioned the undesirable situations that are associated with impacted teeth,
and given the fact that no one can guarantee that an asymptomatic impacted tooth
will not create problems in the future, the choice of removing or preserving
the impacted tooth must be made after considering all the possibilities.
Prevention
of fracture of jaws
Prevention
of Periodontal Disease
Caries on the
distal surface of the second molar, caused by a semi-impacted mandibular
thirdmolar
Caries in the
distal area of the crown of semi impacted third molar, due to entrapment of food
and bad hygiene
Bone resorption
at the distal surface of the root of a mandibular second molar, resulting in a
periodontal pocket
Impacted
mandibular third molar in edentulous area, which erupted after placement of a
partial denture
Obstruction of
the eruption of a mandibular second molar because of an impacted third molar
Impacted
maxillary central incisor, whose eruption was obstructed because of a
supernumerary tooth
Impacted mandibular
third molar with well-defined radiolucency at the distal area
Impacted
mandibular canine that is surrounded by a lesion
Extensive
radiolucent lesion in the posterior area of the mandible, occupying the ramus.
The impacted tooth has been displaced to the inferior border of the mandible.
Extensive
radiolucent lesion in the mandible, extending from the mandibular notch as far
as the canine. The impacted tooth has been displaced to an area high in the ramus
of the mandible
Complete
resorption of the distal root of the left mandibular firstmolar, due to an
impacted second molar
Medical
History
A detailed medical
history is necessary because, based on the information provided, useful
information may be found concerning the general health of the patient to be
operated on. This information determines the preoperative preparation of the
patient, as well as the postoperative care instructions.
Clinical
Examination
During the intraoral
clinical examination, the degree of difficulty of access to the tooth is
determined, especially concerning impacted third molars. When the patient
cannot open his or her mouth, because of trismus that is mainly due to
inflammation, the trismus is treated first, and extraction of the third molar
is performed at a later date. In certain cases of impacted teeth, especially
canines, buccal or palatal protuberance may be observed during palpation or
even inspection, which suggests that the impacted tooth is located underneath.
Also, the adjacent teeth are examined and inspected (extensive caries, large
amalgam restorations, prosthetic appliance, etc.) to ensure their integrity
during manipulations with various instruments during the extraction procedure.
Radiographic
Examination
The radiographic
examination provides us with all the necessary information to program and
correctly plan the surgical removal of impacted teeth. This information includes:
position and type of impaction, relationship of impacted tooth to adjacent
teeth, size and shape of impacted tooth, depth of impaction in bone, density of
bone surrounding impacted tooth, and the relationship of the impacted tooth to
various anatomic structures, such as the mandibular canal, mental foramen, and
the maxillary sinus. These aforementioned data may also be provided by
periapical radiographs and panoramic radiographs, as well as occlusal
radiographs.
Assessment
and Classification of Impacted third molar
Impacted
Third Molar Classification.
The impacted
mandibular third molar may present with various positions in the bone, and so the technique for its removal is determined
by its localization.
The classic positions of the tooth, depending on the direction of the crown of the tooth, are (according to Archer 1975; Kruger 1984):
mesioangular, distoangular,
vertical, horizontal, buccoangular, linguoangular, and inverted. Impacted teeth may also be classified according to their depth
of impaction, their
proximity to the second molar, as well as their localization in terms of the distance
between the distal
aspect of the second molar and the anterior border of the ramus of themandible. As far as the
depth of impaction
is concerned, mandibular third molars may be classified (according to Pell and Gregory
1933) as belonging
to three categories:
Class A: The occlusal surface of the impacted tooth is at
the same level as, or a little below that of, the second molar.
Class B: The occlusal surface of the impacted tooth is at
the middle of the crown of the second molar or at the same level as the
cervical line.
Class C: The occlusal surface of the impacted tooth is below
the cervical line of the second molar As for the distance to the anterior
border of the ramus of the mandible, impacted teeth may be classified as belonging
to one of the following three categories:
Classification
of impaction of mandibular third molars, according to Archer (1975) and Kruger
(1984). (1Mesioangular, 2 distoangular,
3 vertical, 4 horizontal,
5 buccoangular, 6 linguoangular,
7 inverted)
Class 1: The distance between the second molar and the
anterior border of the ramus is greater than the mesio distal diameter of the
crown of the impacted tooth, so that its extraction does not require bone
removal from the region of the ramus.
Class 2: The distance is less and the existing space is
less than the mesiodistal diameter of the crown of the impacted tooth.
Class 3: There is no room between the second molar and
the anterior border of the ramus, so that the entire impacted tooth or part of
it is embedded in the ramus.
Classification
of impacted mandibular third molars according to Pell and Gregory (1933): a according to the depth of impaction and proximity
to the second molar; b their position according to the distance
between the secondmolar and the anterior border of the ramus of the mandible
The above
classification methods refer to all of the aforementioned positions of the
impacted tooth. Furthermore, the number of roots of the impacted tooth and
their relationship to the mandibular canal are taken into consideration. It is
obvious that the cases belonging to Class 3 present more difficulty during the
surgical procedure, because the extraction of the tooth requires removal of a
relatively large amount of bone and there is a risk of fracturing the mandible
and damaging the inferior alveolar nerve.
Winter's
Lines (WAR)
The position & depth of the mandibular 3rd molar can be determined using the Winter’s Lines (WAR). These are 3 imaginary lines (red, amber & white) “drawn” on the dental X-ray (these days, normally an OPG / DPT).
The position & depth of the mandibular 3rd molar can be determined using the Winter’s Lines (WAR). These are 3 imaginary lines (red, amber & white) “drawn” on the dental X-ray (these days, normally an OPG / DPT).
White Line
The white line is drawn along the occlusal surfaces of the erupted mandibular molars & extended over the 3rd molar posteriorly. It indicates the difference in occlusal level of the 1st & 2nd molars & the 3rd molar.
Amber Line
The amber line represents the (height of the) bone level. The amber line is drawn from the surface of the bone on the distal aspect of the 3rd molar (or from the ascending ramus) to the crest of the inter dental septum twixt the 1st & 2nd molars. This line denotes the margin of the alveolar bone covering the 3rd molar and gives some indication to the amount of bone that will need to be removed for the
tooth to come out.
Red Line
The red line is an imaginary line drawn perpendicular from the amber line to an imaginary point of application of an elevator. Usually, this is the cemento-enamel junction on the mesial aspect of the impacted tooth (unless, it is the disto-angular impacted tooth where the application point is the distal cemento-enamel junction). The red line indicates the amount of bone that will have to be removed before elevation of the tooth i.e. the depth of the tooth in the jaw & the difficulty encountered in removing the tooth.
With each increase in length of the red line by 1mm, the impacted tooth becomes 3 x more difficult to remove (as opined by Howe). If the red line is < 5mm, than the tooth can be removed under just LA; anything above, a GA or LA Sedation would be more appropriate.
Another method of judging the depth
of the 3rd molar is to divide the root of the 2nd molar into thirds. A
horizontal line is drawn from the point of application for an elevator to the 2nd molar.
If the point of application is adjacent to the coronal, middle or apical
root third, then the tooth extraction is assessed as easy, moderate or
difficult respectively.
Steps
of Surgical Procedure
The surgical procedure
for the extraction of impacted teeth includes the following steps:
1. Incision and
reflection of the mucoperiosteal flap
2. Removal of bone to
expose the impacted tooth
3. Luxation of the
tooth
4. Care of the
postsurgical socket and suturing of the wound
The main factors for a
successful outcome to the surgical procedure are as follows:
·
Correct
flap design, which must be based on the clinical and radiographic examination (position
of tooth, relationship of roots to anatomic structures, root morphology).
·
Ensuring
the pathway for removal of the impacted tooth, with as little bone removal as
possible. This is achieved when the tooth is sectioned and removed in segments,
which causes the least trauma possible.
Principles of
Mucoperiosteal flap design
1.
Preservation
of blood supply
2.
Adequate access
3.
Prevent damage
to vital structures
4.
Incision margins
should lie on sound bony margins
5.
Ease of
repositioning
Types
of Flaps.
According to the
type of incision
·
Envelope
·
Two sided
·
Three
sided
·
Apically
repositioned flap
·
Semilunar
According to the
thickness
·
Full
thickness
·
Partial
thickness
According to the
site
·
Labial or
buccal flap
·
Palatal or
Lingual flap
Many types of flaps
may be used when surgically removing impacted mandibular third molars: the
triangular and the envelope flap are the commonest using flaps. The choice depends
on the evaluation of the various data pertaining to the case (e.g., depth of
impaction, position, etc.).
Triangular flap:
The incision for this
type of flap begins at the anterior border of the ramus (external oblique
ridge) with special care for the lingual nerve and extends as far as the distal
aspect of the second molar, while the vertical releasing incision is made
obliquely downwards and forward, ending in the vestibular fold In certain
cases, e.g., when impaction is deep, to ensure a satisfactory surgical field or
when the impacted tooth conceals the roots of the second molar, the incision
may continue along the cervical line of the last tooth while the vertical
incision begins at the distal aspect of the first molar.
Variation of
incision shown in figure (vertical releasing incision is distal to the first
molar). The mesial extension of incision is necessary due to the position of
the third molar compared to the second molar
Horizontal
(envelope) flap:
The incision for the
flap also begins at the anterior border of the ramus and extends as far as the
distal aspect of the second molar, continuing along the cervical lines of the
last two teeth, and ending at the mesial aspect of the first molar. This type of
flap is usually used in cases where impaction is relatively superficial.
Clinical
photograph and b diagrammatic illustration showing incision for
envelope flap
Anesthesia.
Anesthesia in cases of
impacted mandibular third molars is achieved by: inferior alveolar nerve block,
buccal nerve block, lingual nerve block, and local infiltration for hemostasis
in the surgical field.
Techniques
of bone removal
·
Use of
Burs
·
Use of
chisel and mallet
Bone removal with
burs-Points to remember
·
Copius
irrigation
·
Protect
vital structures
Principles
of closure of flaps
·
Gentle tissue
handling
·
Not too
tight sutures
·
Haemostasis
prior to closing
·
Avoid dead
space
·
Decontamination
and debridement
·
Proper approximation
Surgical removal
of different types of impactions will be discussed in later posts
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