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BDS4 Oral Surgery > Third Molars > Flashcards

Third Molars Flashcards

1
Q

Patient factors and medical considerations for extraction of third molars?

A

Medical indications - awaiting cardiac surgery, immunosuppressed, pre-cancer therapy

Patient age - complications and recovery time increase with age.

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2
Q

What times do crown and root calcification of third molars occur?

A

Crown calcification begins between 7-10 years and finishes by age 18 years
Root calcification complete between 18-25 years

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3
Q

What nerves are at risk during third molar surgery?

A

Inferior alveolar nerve
Lingual nerve
Nerve to mylohyoid
Long buccal nerve

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4
Q

Pericoronitis signs and symptoms

A

Pain
Swelling
Bad taste
Pus discharge
Occlusal trauma to operculum
Ulceration of operculum
Evidence of cheek biting
Halitosis
Limited mouth opening
Dysphagia
Malaise
Regional lymphadenopathy

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5
Q

What is pericoronitis treatment?

A
  • Irrigation with saline or CHX blunt needle under operculum (+/- LA)
  • Pt. instructed on frequent warm saline or CHX mouth-rinse
  • Analgesia advice
  • Instruct pt. to keep fluid levels up and keep eating
  • Antibiotics if infection is severe

Extraction of opposing molars if traumatising operculum

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6
Q

What are predisposing factors for pericoronitis?

A

Partial eruption and vertical or disto-angular impaction
Opposing maxillary or M3M or M2M causing mechanical trauma contributing to recurrent infection
Stress
Poor OH
White race
Insufficient space between the ascending ramus of the lower jaw and distal aspect of M2M

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7
Q

What radiographic signs are associated with significantly increased risk of nerve injury during third molar surgery?

A

Diversion of IAN
Darkening of the root where crossed by the canal
Interruption of white lines of the canal

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8
Q

What is the OPT needed to determine?

A

Presence or absence of disease (in 3M or elsewhere)
Anatomy of 3M (crown size, shape, condition, root formation)
Depth of impaction
Orientation of impaction
Working distance (distal of lower 7 to ramus of mandible)
Follicular width
Periodontal status
The relationship or proximity of upper third molars to the maxillary antrum and of lower third molars to the inferior dental canal
Any other assoc pathology

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9
Q

How can mild, moderate and deep impaction be explained?

A

Mild impaction - where the crowns of 7’s and 8’s sit at the same height
Moderate impaction - anywhere between the 2.
Deep impaction - when the crown of the 8 sits at the level of the roots of the 7

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10
Q

When is a CBCT required/ justified?

A

If close relationship between third molar and IAC is suspected (e.g. from OPT) and need further imaging to determine tooth location.

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11
Q

In what situation would you require PA’s of teeth following an OPT?

A

For caries detection - cannot always assess caries well on OPT.

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12
Q

What is the definition of transverse angulation/ impaction?

A

When the crown is buccally placed and roots are lingually placed or vice versa.

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13
Q

What is the word for when a 3rd molar tooth is in an odd place?

A

Abberant

e.g. mid-way up the ramus of the mandible

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14
Q

What is the angulation/ orientation of M3M’s measured against?

A

Curve of spee and M2M’s (which are vertical)

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15
Q

What are common treatment options for retained 3rd molars?

A

Monitor and review
Removal of M3M/ maxillary 3rd molar
Coronectomy

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16
Q

What are less common treatment options for retained 3rd molars?

A

Operculectomy
Surgical exposure - may encourage 3rd molar to erupt into mouth
Pre-surgical orthodontics
Auto-transplation

17
Q

When is a coronectomy of M3M’s indicated?

A

When the roots of M3M are closely associated with the IAC but tooth is symptomatic

18
Q

Why are operculectomy’s not commonly carried out?

A

Gingivae generally grows back over the tooth fairly quickly which renders them essentially useless

19
Q

What is the management for asymptomatic, diseased/ high risk of disease developing M3M’s?

A

Surgical intervention should be considered.
If tooth has a higher risk of surgical complications, then active surveillance until symptoms develop or early disease progression has been proven.

20
Q

What is the management for asymptomatic non-diseased/ low-risk of disease developing M3M’s?

A

Clinical review + radiographic assessment if required

Do not remove asymptomatic, low-risk M3M’s - leave.

21
Q

What medical factors should be considered/ indicate prophylactic removal of M3M’s?

A

Patients about to start
- bisphosphonates or other anti-resorptive drugs
- Radiotherapy of head and neck
- Immunosuppressant therapy

22
Q

What surgical factors should be considered/ indicate removal of M3M’s?

A

If the third molar lies within the perimeter of a surgical field

Mandibular fractures
Orthognathic surgery
Resection of disease (benign and malignant lesions)

23
Q

What is the management for symptomatic, non-diseased/ low-risk of disease development M3M’s?

A

Consider other causes of pain symptoms

Leave deeply impacted M3Ms with no associated disease

Manage other diagnoses causing pain in the region:
TMD
Skin lesions
Migraines/ headaches
etc.

24
Q

After what period of time, would altered sensation or nerve numbness be unlikely to recover?

A

18-24 months

25
Q

In what circumstance would a lower 8 NOT be suitable for a coronectomy, even if close to the IAC?

A

Where the lower 8 is grossly carious

26
Q

What % of patients will experience temporary numbness of lower lip and chin following third molar surgery?

A

10%

27
Q

What % of patients will experience permanent numbness of lower lip and chin following third molar surgery?

A

<1%

28
Q

What % of patients will experience temporary numbness/ altered taste on one side of tongue following third molar surgery?

A

0.25- 23%

29
Q

What % of patients will experience permanent numbness/ altered taste on one side of tongue following third molar surgery?

A

0.14 - 2%

30
Q

Regarding SIGN guidelines, when are impacted third molars NOT advisable to be removed?

A

8’s predicted to erupt healthy
MH precludes XLA
Deeply impacted with no pathology
High risk of surgical complications
Risk of mandibular fracture
Asymptomatic contra-lateral 8 under LA

31
Q

What diseases may affect the healing process for pericoronitis or third molar surgery?

A

Diabetes
Renal disease
Liver disease
Bleeding disorders
Immunosuppression
Had/ awaiting cancer treatment
Contraceptive
Bisphosphonates

32
Q

What may be seen radiographically that would indicate close proximity of M3M to ID canal?

A

Interruption of tram lines of the canal
Darkening of the root where crossed by the canal
Diversion/ deflection of ID canal
Deflection of root
Narrowing of inferior dental canal
Narrowing of the roots
Dark and bifid root - root appears to split or divide over the canal

33
Q

According to SIGN guidelines, what are STRONG INDICATIONS for extraction of lower 8?

A

Previous infection
Caries in 8 with little chance of useful restoration or caries in 7 that is un-restorable without removal of the 8
Perio disease due to position of the 8 and association to the 7
Cyst formation or other related pathology
External resorption of the 8 or 7, where it appears caused by the 8

34
Q

4 local things that would make third molar surgery difficult

A

Depth of impaction
Distance between distal of 7 and ascending ramus of mandible
Angulation of impaction
Root morphology

BDS4 Oral Surgery (9 decks)

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