smile care dental clinic
Friday, 1 June 2012
Definition of Impacted tooth”
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.
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
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