impacted third molars

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Impacted Third Molars

• Dr Naveed Iqbal

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Definition of impaction

• An impacted tooth is one that fails to erupt into
  dental arch with in expected time due to lack of
  space, abnormal position and
• Most commonly impacted teeth are mandibular and
  maxillary third molars, maxillary canine and
  mandibular premolars.

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Indications of extraction

• All impacted third molars should be removed as
  soon as diagnosis is made.
• Surgical removal in early age results in less
  number of complications and surgery would be
  relatively easy.
• Average age of completion of eruption of third
  molars is 20 years although eruption may continue
  up to 25 years of age.
• Lower Third molars start to develop in horizontal
  direction the angulation changes from horizontal
  to mesioangular to vertical during jaw growth.
  Most impacted teeth fails to rotate from
  mesioangular to vertical.

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Indications for removal

• Prevention of periodontal disease
• Prevention of caries
• Prevention of pericoronitis
• Prevention of root resorption
• Preprosthetic extraction deeply embedded
  wisdom teeth should not be removed in old
  patients.
• Prevention of odontogenic cyst and tumors
• Treatment of pain of unexplained origin
• Prevention of jaw fracture in the area of angle
  of mandible
• Facilitation of orthodontic treatment for molar
  distalization and placement of retromolar
  implants.
• optimal periodontal healing.

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Periodontal disease and caries
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Root resorption
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Pathological lesion
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Jaw fracture
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Optimal periodontal healing after removal of
third molar

• Two factors are important for optimal periodontal
  healing of periodontal bone loss distal to 2nd
  molar.
• 1. extent of preoperative infra bony defect.
• 2. Age of patient at the time of surgery.
• If large amount of bone is missing and patient is
  of more than 25 years of age likely hood of
  periodontal healing is reduced.
• Asymptomatic completely bony impacted third molar
  in patients of more than 30 years of age should
  not be extracted due to increase risk of
  periodontal bone loss.

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Contra indications for third molar removal

• Extremes of age
• early removal of third molar bud or germectomy
  should not be performed.
• Ideal time of impacted third molar removal is 17
  to 20 years when 1/3 root is formed.
• Most common contraindication for removal of third
  is advanced age. Because bone hard and un
  flexible in this age group and more bone is
  required to be removed to deliver the tooth.
• Old patient also have more post operative
  complications and slow recovery.
• Asymptomatic pathology free, deeply embedded
  third molars in patients of gt 35 years of age
  should not be removed.

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Contraindications for third molar removal

• Compromised medical status
• Asymptomatic wisdom teeth in medically
  compromised patients should not be extracted.
  However in symptomatic cases consult patient
  physician.
• Possible excessive damage to adjacent structure
• Asymptomatic teeth in old age patient with
  possible risk of damage to adjacent nerve, teeth
  and prosthesis should not be removed.

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Classification systems of impacted teeth

• Angulation
• Relationship to anterior border and ramus (Pell
  and Gregory classes 1,2,3)
• Relationship of occlusal plane (Pell and Gregory
  A, B, C)

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Angulation

• Refers to the angulation of the long axis of the
  impacted M3 with respect to long axis of M2
• 4 types of angulations
• Mesioangular-
• Horizontal
• Vertical
• Distoangular

Contd..
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Mesioangular Impaction
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Horizontal Impaction
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Vertical Impaction
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Distoangular Impaction
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Ramus relationship- Pell and Gregory classes 1,2,
and 3

• Based on the amount of impacted tooth that is
  covered with bone of the mandibular ramus.
• Class I crown completely anterior to ramus.

Contd..
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Ramus relationship- Pell and Gregory classes 1,2,
and 3

• Class II ? ½ crown is covered by ramus- such a
  tooth cannot be expected to erupt in normal
  position

Contd..
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Ramus relationship- Pell and Gregory classes 1,2,
and 3

• Class III tooth located completely within
  mandibular ramus- least accessible and most
  difficult to remove

Contd..
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Depth/ Pell and Gregory A, B, C classification

• Refers to the depth of impacted tooth compared
  with the height of the adjacent M2.
• The degree of difficulty is measured by the
  thickness of the overlying bone- difficulty ? as
  depth of impacted tooth ?

Contd..
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Pell and Gregory A, B, C classification

• Class A occlusal surface of impacted M3 is at
  level or nearly level with M2

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Pell and Gregory A, B, C classification

• Class B occlusal surface of impacted M3 is
  between occlusal plane and cervical line of M2

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Pell and Gregory A, B, C classification

• Class C occlusal surface of impacted M3 is below
  the cervical line of M2

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Root morphology

• Root morphology determine the difficulty of
  extraction.
• Teeth with long, curved, divergent roots are
  difficult to extract.
• it is better to extract the tooth when half to
  2/3 roots are formed.
• If roots of a mesioangular impaction are curved
  in distal direction extraction is easy.
• If mesiodistal width of the root is greater than
  crown width extraction is difficult.

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Size of follicular sac

• Large radiolucency of tooth follicle around
  impacted third molar makes extraction easy as
  much less amount of bone is likely to be removed.
• Young patients have large follicles.
• Narrow follicular space require large amount of
  bone removal.

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Density of surrounding bone

• Bone density is best determined by age because
  radiographs are less reliable.
• Patients of 18 years of age or younger have less
  dense bone which can be easily removed with bur
  and can easily expanded with elevators.
• Patients of more than 35 years of age have denser
  bone and it is not possible to expand the socket.
  Bone is difficult to remove and likely to
  fracture.

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Contact with mandibular 2nd molar

• If large space exist between 2nd molar and 3rd
  molar extraction is easy.
• Horizontal and distoangular teeth are frequently
  in direct contact with 2nd molars.
• If 2nd molar have large restoration or
  endodontically treated it is likely to fracture
  during elevation of third molar. Patient should
  be informed before surgery.

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Relationship to IDN

• Impacted lower third molars are in close
  proximity with inferior alveolar canal and canal
  usually lies on buccal aspect of tooth.
• Very rarely the contents of ID canal actually
  perforate the tooth root and in these cases there
  will be a loss of parallel lines of the canal.
• If the roots are in close relationship to ID
  canal, the patient should be warned of the
  possibility of impaired labial sensations

Contd..
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Relationship to IDN
Contd..
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Nature of overlying tissues

• According to the nature of overlying tissues, the
  impactions are classified into 3 types
• soft tissue impaction
• partial bony impactions
• full bony impactions

Contd..
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Classification of maxillary M3

• Angulations
• Vertical impactions- 63 easiest
• Distoangular impaction- 25 easiest
• Mesioangular impaction- 12 most difficult
• Rare- transverse, inverted, horizontal lt1

Contd..
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Maxillary M3 impactions
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Pell and Gregory Classification for Maxillary M3

• Pell and Gregory A, B and C classification for
  depth of impaction in the mandible is utilized in
  the maxilla.

Contd..
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Pell and Gregory Classification for Maxillary M3

• Class A
• Occlusal surface of M3 is at the same level
  as that of M2

Contd..
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Pell and Gregory Classification for Maxillary M3

• Class B
• Occlusal surface of M3 is located between
  occlusal plane and cervical line of M2

Contd..
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Pell and Gregory Classification for Maxillary M3

• Class C
• Impacted M3 is deep to cervical line of M2

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Factors which make impaction surgery difficult

• Lower wisdom
• Distoangular
• Class 3 and position c
• Long, thin divergent roots
• Narrow PDL space
• Small follicle
• Dense bone
• Contact with 2nd molar
• Close to ID canal
• Complete bony impaction

• Upper wisdom
• Mesioangular
• Thin multiple roots
• Thin PDL space
• Small follicle space
• Dense bone
• Contact with 2nd molar,
• Complete bony impaction
• Relationship with maxillary sinus.
• Dense bone of maxillary tuberosity.

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Surgical removal techniques

• Remember the 5 basic steps
• 1.Reflect adequate soft tissue flap for
  
• exposure and access.
• 2.Bone removal
• 3. Sectioning of tooth
• 4. Deliver the sectioned pieces with
• elevators
• 5. wound closure

Contd..
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The mucoperiosteal flap

• Full thickness flap is raised on buccal side of
  impacted third molar.
• Envelope flap is usually preferred- easier to
  close and heals better. it starts from mesial
  papilla of first molar to posteriorly and
  laterally to anterior surface ramus. (External
  oblique ridge)
• Three-sided flap- if greater access to apical
  areas is required. It starts from mesial papilla
  of 2nd molar and extended laterally and
  posteriorly to anterior surface of ramus. Oblique
  releasing incision is given mesial to 2nd molar.

Contd..
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Bone removal

• Bone is removed with large round bur in surgical
  hand piece.
• For lower third molars bone is removed initially
  removed from occlusal, buccal and distal surface
  of tooth up to cervical line. After initial bone
  removal Ditching is performed
• For maxillary wisdom teeth bone removal is
  usually unnecessary when required bone is removed
  from buccal side of tooth down to cervical line.
  Additional bone is removed from mesial side for
  the application of elevator.

Contd..
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Tooth sectioning

• Can be done with bur
• When using a bur, section the tooth 3/4th of the
  way towards the lingual aspect- then insert
  straight elevator and rotate to split the tooth.
  Going through the lingual side ? likelihood of
  damaging lingual nerve.
• Sectioning of third molar depend upon angulation
  of wisdom tooth.

Contd..
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Mesioangular
Contd..
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Horizontal impaction
Contd..
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Vertical impaction
Contd..
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Distoangular impaction
Contd..
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Impacted maxillary M3
Contd..
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Delivering the pieces

• Delivered with elevators
• Never use excessive force
• In delivering maxillary third molars
• avoid damage to root of maxillary M2
• place finger on tuberosity, (especially if the
  impaction is mesioangular), so that the tooth
  does not slip in pterygoid space and also to
  detect any fracturing of the tuberosity

Contd..
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Debridement and closure

• Remove bone chips and debris
• Specially irrigate under the reflected flap
• Thoroughly debride and irrigate socket to clear
  debris
• Bone file to smoothen rough and sharp edges
• Remove any remnant of dental follicle with
  hemostat
• Check for control of bleeding
• Apply damp gauze pack
• Place tetracycline powder into socket to prevent
  dry socket.
• Closure with sutures. For lower wisdom first
  suture is placed distal to 2nd molar another
  suture is placed posteriorly and one anteriorly
  mesial to 2nd molar (total 3 sutures). For upper
  wisdom if flap rest passively Sutures may not be
  required.

Contd..
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Postoperative care

• Warn the patient of pain, swelling and limited
  mouth opening.
• Consider use of sedation or GA to control anxiety
  during difficult extractions.
• Consider use of long acting local anesthesia
  bupivacaine. 4 to 8 hours action
• Provide analgesia for 3-4 days codiene with
  aspirin or brufen.
• Swelling completely dissipated by about 10 days.
  Preoperative single dose 8 mg dexamethasone long
  acting steroid.
• Mild soreness persists for about 2-3 weeks
• Trismus usually resolves in about 10 days. Warn
  patient before surgery
• Post op antibiotics- if there is pre-existing
  infection give antibiotics.
• Place ¼ capsule of tetracycline into socket to
  prevent dry socket.