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Module 6 - Oral Surgery > Impacted Third Molars > Flashcards

Impacted Third Molars Flashcards

1
Q

7 cases where a surgical extraction would be required?

A
  1. Gross caries so unable to use forceps and no application point for elevators.
  2. Complex root morphology even if the crown is intact (ex. convergent, divergent, bulbous, ankylosed).
  3. Retained roots below the alveolar bone so no point of application for elevators.
  4. Impacted teeth
  5. Displaced teeth
  6. Ectopic teeth
  7. Pathology
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2
Q

What is the MOST COMMON CAUSE that teeth become impacted?

A

Lack of SPACE in the arch as a consequence of evolutionary changes and less abrasive diet.

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3
Q

What guidelines can we consult for the removal of third molars?

A

National Institute for Clinical Excellence (NICE) 2000

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4
Q

What are the SIGN guidelines for removal of third molars?

A

Scottish Intercollegiate Guideline Network (SIGN 43) 2000 - WITHDRAWN IN 2015 HENCE NO LONGER APPLY TO SCOTLAND, USE NICE 2000 INSTEAD.

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5
Q

3 causes of impaction?

A
  • Lack of space.
  • Development in an abnormal position.
  • Pathological change (pushes tooth away from eruptive position).
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6
Q

What is physiological mesial drift?

A

Teeth move FORWARD/ MESIAL in the arch as we get older. This depended on the teeth becoming narrower through an abrasive diet/ attrition.

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7
Q

Rank teeth from most to least often impacted?

A
  1. Mandibular third molars.
  2. Maxillary canines.
  3. Mandibular premolars/canines.
  4. Maxillary incisors.
  5. Maxillary third molars.
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8
Q

What teeth are often impacted?

A

Those that erupt LATEST.

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9
Q

Define ectopic?

A

Tooth malpositioned due to CONGENITAL factors (ex. cleft lip and palate affect laterals and canines).

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10
Q

Define displaced?

A

Malposition dueto presence of PATHOLOGY (ex. cyst).

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11
Q

What ratio of mandibular third molars fail to develop?

A

1:4

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12
Q

What % of mandibular 3rd molars is impacted?

A

72%

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13
Q

What happens during eruption?

A

Tooth moves from its developmental position to its functional occlusal position

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14
Q

What does the decision to remove mandibular third molars depend on?

A

Balance of risk of observation against removal before overt disease develops.

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15
Q

What is the most common indication for XLA of mandibular 3rd molars?

A

Pericoronitis (59%)

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16
Q

11 indications for removal of mandibular 3rd molars?

A
  • Pericoronitis.
  • Unrestorable caries in 8 or 7.
  • Cellulitis/ osteomyelitis.
  • Periodontal disease in 7 (especially >30 years).
  • Orthodontic reasons.
  • Prophylactic removal in medically compromised.
  • Obscure pain.
  • Tooth in line of fracture.
  • Disease of follicle (cyst, tumor).
  • Orthognathic surgery.
  • Transplant donor.
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17
Q

At what age is periodontal disease of the 7 due to the 8 particularly concerning? Why?

A
  • Over 30.
  • Periodontal pockets less likely to heal.
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18
Q

What is obscure pain?

A

Unable to pin-point the cause of someone’s pain.

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19
Q

2 reasons for prophylactic removal of the 8s in medically compromised patients?

A
  • Patient who will undergo radiation to the jaws, become less vascularized and prone to necrosis.
  • Patient who will receive a transplant and will thus be IMMUNOCOMPROMISED.
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20
Q

Why must cysts be removed? How are these managed?

A
  • While they expand they weaken the jaws and increase risk of FRACTURE.
  • Require SURGICAL management under GA.
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21
Q

Why are teeth at fracture lines often removed?

A
  • Any tooth in a fracture line will be rendered NON VITAL.
  • Thus remove teeth when managing fracture as patient likely to develop symptoms in the future.
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22
Q

Define pericoronitis?

A

Inflammation of the tissues around the crown of any partially erupted/impacted tooth.

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23
Q

9 clinical features of pericoronitis?

A
  • Trismus.
  • Pain.
  • Dysphagia.
  • Malaise.
  • Bad taste.
  • Halitosis.
  • Food packing.
  • Inflammation of the pericoronal tissues with pus.
  • Cheek biting and cuspal indentations on the operculum.
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24
Q

Define operculum

A

Flap of gum covering a partially erupted tooth.

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25
Q

What is an operculectomy?

A

Cutting off the operculum, HOWEVER:
- Painful.
- Operculum will likely grow back.
- Does not solve the problem - insufficient space in arch for the 8.

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26
Q

How can you identify that an upper tooth is occluding onto the operculum of the partially erupted 8? What can be done?

A

WHITE, KERATINIZED GUMS are a SIGN OF TRAUMA.
- Grind the cusps of the molar.
- XLA upper 8 (if that is causing the issue).

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27
Q

Is pericoronitis an indication to XLA a mandibular 3rd molar?

A
  • One isolated incident is NOT an indication to remove the tooth.
    TWO OR MORE EPISODES OF PERICORONITIS ARE AN INDICATION TO RECOMMEND REFERRAL FOR XLA.
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28
Q

what is the management for pericoronitis?

A
  1. LOCAL MEASURES (if systemically well).
    - Irrigate with SALINE.
    - Oral hygiene (small headed brush/ waterpik).
    - Remove trauma (XLA upper 8 or grind upper 7).
  2. GENERAL MEASURES (systemically unwell).
    - Analgesics.
    - Antibiotics.
    - Admission in severe airway threatening cases).
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29
Q

When would you prescribe antibiotics for pericoronitis?

A
  • When the patient is SYSTEMICALLY UNWELL (ex. malaise, lymphadenopathy, fever) or IMMUNOCOMPROMISED (poorly controlled diabetic, immunosuppressants).
  • When management under LA is not possible (trismus, patient compliance).
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30
Q

What is the microbiology of pericoronitis?

A

Primarily ANAEROBIC.

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31
Q

What are the 4 treatment options for mandibular 3rd molars?

A
  1. Conservative.
  2. Operculectomy.
  3. Removal.
  4. Coronectomy.
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32
Q

6 things to look at in a mandibular 3rd molar radiograph?

A
  • Tooth.
  • Angulation/ impaction.
  • Shape and morphology of the root.
  • Relationship to IAN canal.
  • Condition of the adjacent teeth.
  • Evidence of pathology, external root resorption, caries.
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33
Q

4 ways to radiographically classify mandibular 3rd molars?

A
  1. Depth. (Winters lines)
  2. Relation to the 7 (crown, ACJ, root)
  3. Angulation to adjacent teeth (vertical, mesioangular, distoangular, horizontal, transverse, aberrant).
  4. Proximity to the ID nerve
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34
Q

What are winter’s lines?

A

Lines used to assess HOW MUCH BONE IS LIKELY TO BE REMOVED WHEN DOING SURGERY

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35
Q

What does the vertical/ red winter line indicate?

A

Where the point of application is for elevation.

36
Q

What are the 2 most common position for mandibular 3s to be impacted?

A
  • Vertical. (30-38%).
  • Mesioangular (40%)
37
Q

What is the commonest way we describe impacted 3rd molars?

A

Based on ANGLE.

38
Q

6 radiographic indications of a close relationship between the lower third molar and the IDC?

A
  • Diversion of the IDC.
  • Narrowing of the IDC.
  • Loss of lamina dura of the IDC.
  • Darkening of the root as it crosses the IDC.
  • Juxta-apical area.
  • Deflection of roots as they approach the IDC,
39
Q

Combination of 3 radiographic signs that imply a HIGH RISK RELATIONSHIP BETWEEN MANDIBULAR 3RD MOLAR AND IAC?

A
  • Loss of lamina dura + darkening of roots in the area + juxta apical area.
40
Q

Define neuropraxia?

A

Bruising of the nerve that causes TRANSIENT altered sensation.

41
Q

What is the positional relationship between the IAC and the mandibular 3rd molar?

A

THE VAST MAJORITY OF IAC SIT ON THE LINGUAL ASPECT OF THE 3RD MOLARS - UP TO 70%.

42
Q

Is the IAC always visible on radiograph?

A

Only visible when in CORTICAL BONE. If sitting in MEDULLARY bone, it can be difficult to make them out.

43
Q

Post operative alteration in sensation?

A
  1. LIP
    - short term: 5%
    - Long term: less than 1%.
  2. TONGUE
    - Short term: 10%.
    - Long term: less than 1%.
    - Taste can be affected.
44
Q

Why may taste be affected following XLA of a mandibular molar?

A
  • Lingual nerve carries CHORDA TYMPANI which supplies TASTE SENSATION to the taste buds.
45
Q

Why was there a higher incidence of altered sensation of the tongue in the past?

A

Due to surgical technique. Used to use HARRIS PERIOSTEAL ELEVATOR to retract the lingual tissues, causing NEUROPRAXIA PERIOPERATIVELY.

46
Q

What is coronectomy?

A

Remove the crown and leave the roots in place.

47
Q

what must you do when consenting the patient for coronectomy?

A

Inform them that the plan is to coronect the tooth however REMOVAL MAY BE UNAVOIDABLE!.

  • If the roots become mobile at the time of coronectomy, they must be removed.
48
Q

2 post-operative risks of coronectomy ? (with %)

A
  • Root infection: 2.9%.
  • Root migration: 14-81%.
49
Q

When is the follow up for a coronectomy?

A

Must have a 1 year radiographic follow up to assess for root migration.

50
Q

What is the evidence for coronectomy?

A
  • “LIKELY” associated with reduction in nerve damage with no increase in alveolar osteitis.
  • EVIDENCE ANECDOTAL, MAY IMPROVE THE SITUATION BUT MAY MAKE THINGS WORSE LONG TERM.
51
Q

When can CBCT be used for mandibular 3rd molars?

A
  • CANNOT be used routinely.
  • Use where conventional imaging has shown a close relationship between 3M3 and the IAN canal and the findings are expected to ALTER MANAGEMENT DECISIONS.
52
Q

5 steps that must be discussed with the patient when planning to undertake surgical XLA of mandibular 3rd molars?

A
  1. Decision on method of anesthesia.
  2. Pre operative warnings of pain, swelling, bruising, trismus, diet (for a WEEK) and altered sensation of lip/ tongue.
  3. Verbal and written warnings, nurse as witness.
  4. Warn of post-operative complications wit a greater than 5% incidence.
  5. If patient declines treatment, must inform of likely long-term problems.
53
Q

When is the pain from surgical XLA worst? When does it get better?

A
  • Worst days 3-5.
  • Better by day 7.
54
Q

4 types of altered sensation?

A
  • Anesthesia: numb.
  • Paraesthesia: tingling.
  • Hypoesthesia: not fully numb.
  • Dysesthesia: pain without painful stimulus.
55
Q

5 risks of not undertaking mandibular 3rd molar XLA?

A
  • Caries in 7 and 8.
  • Recurrent pericoronitis.
  • Periodontal disease.
  • External root resorption.
  • Cyst formation
56
Q

What is the flap design for XLA of mandibular third molars (simple)?

A
  • TRIANGULAR FLAP

(ENVELOPE flap for more experience operators).

57
Q

Give the name and detailed description of the flap raised to surgically XLA mandibular 3rd molars?

A

TRIANGULAR FLAP:
- Distal relieving incision up the ASCENDING RAMUS.
- Around the crown of the 3M + include papilla between 3M and 2M.
- Mesial relieving incision.

(envelope flap has no mesial relieving incision).

58
Q

What is used to elevate the flap along the gingival margins? (4)

A

a PERIOSTEAL ELEVATOR.
- Warwick james.
- Mitchells trimmer.
- Molt no.9 periosteal elevator.
- Howarth’s periosteal elevator.

59
Q

What is used to retract the flap along the buccal flap? (2)

A
  • Howarths.
  • Rake retractor.
60
Q

How do we raise a lingual flap (3)? Why?

A
  • Raise using Mitchells/Molt/Howarths.
  • To protect the lingual nerve in selected cases.
  • NOT FOR NOVICE OPERATORS.
61
Q

What will you see if you have cut the flap correctly?

A
  • Pale colored bone, the ALVEOLUS.
  • If tissue if very pink, you have left the periosteum behind.
62
Q

When is an envelope flap design used for the XLA of mandibular 3rd molars (3)?

A
  • Pericoronal pathology.
  • Cyst.
  • Unsure how must bone will have to be removed/
63
Q

What is an envelope flap?

A

No mesial relieving incision, instead extend pericoronal incision around the tooth in front.

64
Q

Advantage of an envelope flap?

A

Can keep extending it to make it bigger if required.

65
Q

2 reasons why bone removal is done?

A
  • Relieve impaction.
  • Create a point of application.
66
Q

What is used to remove bone?

A

a SURGICAL HANDPIECE with BURS
- Round bur: create a narrow gutter mesiobuccally.
- Fissure bur: deepen in and make it narrower.

67
Q

What is used alongiside the surgical handpiece? Why?

A

SALINE to stop the bone from overheating.

68
Q

Where do we mostly remove bone?

A

Mostly from the BUCCAL aspect.
- NEVER cut away the lingual plate to not damage the lingual nerve.

69
Q

2 ways in which you can section a crown?

A
  • Horizontally (horizontal impaction).
  • Axially (from the furcation upwards).
70
Q

2 types of impactions where crown sectioning is recommended?

A
  • HORIZONTAL IMPACTIONS - all horizontally impacted teeth must have crown sectioned off.
  • DISTOANGULAR IMPACTION - avoid excessive bone removal but ensuring application point.
71
Q

Why are crowns often sectioned (2)?

A
  • Disimpact the tooth.
  • Reduce required bone removal.
72
Q

2 cases where division of roots would be needed?

A
  • Pincer roots (convergent roots).
  • Multiple root with differing paths of removal.
73
Q

2 reasons why elevators are used during surgical XLA?

A
  • Elevate the roots.
  • Complete the sectioning of crowns/ roots.
74
Q

What is important regarding flap design?

A

Must ensure that after surgery, the flap rests on BONE to AVOID WOUND BREAKDOWN.

75
Q

Which is the most important suture?

A

The one placed from the buccal tissues to the lingual tissues immediately distal to the second molar tooth to encourage good periodontal health.

76
Q

How many sutures should be used to suture the flap?

A

the fewer sutures placed the better to secure primary closure and haemostasis.
- generally at least 2

77
Q

What material are sutures made of?

A

3/0 Vicryl rapide

78
Q

What is anatomical closure?

A

In a PARTAILLY ERUPTED TOOTH, acceptable to realign the flap exactly where it was and thus dont get entirely primary closure as long as HEMOSTASIS is achieved.

79
Q

6 steps of post-operative regime?

A
  • Analgesics (and antibiotics).
  • HSMW.
  • Soft diet.
  • Topical ice packs.
  • Suture removal at 1 week if not resolvable.
  • Follow up for difficult cases/ immunocompromised.
80
Q

Ice packs following surgical XLA?

A
  • best on the DAY of treatment within 6 hours
  • 15 mins on 15 off.
81
Q

Complications associated with surgical XLA of mandibular 3rd molars (6)?

A
  1. haemorrhage- primary or secondary
  2. loose teeth or damage to adjacent teeth/restorations periodontium.
  3. fractured mandible
  4. dry socket [1-5%] or infection with purulent discharge
  5. sensory deficit-IDB=5% temp, lingual temp=10%, perm=<1%
  6. complications generally associated with extraction’s
82
Q

How are maxillary 3rd molars often impacted? (2)

A
  • Vertically.
  • Mesio angular
83
Q

2 reasons why XLA of maxillary 3rd molars is easier?

A
  1. Thin cortical bone buccally.
  2. Short single root in 74% of cases.
84
Q

3 reasons why access of the maxillary 3rd molars is difficult.

A
  • Behind second molars
  • Malar buttress
  • Buccal position
85
Q

2 things unerupted 3rd molars can cause?

A
  • Resorption of adjacent teeth.
  • Pathology (ex. cyst formation).
86
Q

How are erupted maxillary 3rd molars extracted?

A
  • Elevators or forceps.
87
Q

How are unerupted maxillary 3rd molars extracted?

A
  1. Raise buccal flap (similar as for lower).
  2. Thin bone removed with couplands.
  3. Elevator used to move tooth DOWN, BACK AND BUCCALLY (avoid excessive upwards force due to displacement into antrum).
  4. One suture to reposition flap.

Module 6 - Oral Surgery (11 decks)

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