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🔵BDS4 Oral Surgery > Third Molars > Flashcards

Third Molars Flashcards

1
Q

When do 3rd molars:
1. Erupt
2. Crown calcification
3. Root calcification

A
  1. 18 - 24y
  2. 7 - 10y (if not present at 14 then absent)
  3. 18 - 25y
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2
Q

Rate of Agenesis of third molars

A
  • agenesis = failure of organ to develop
  • 1 in 4 adults at least one absent 3rd molar
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3
Q

What causes a 3rd molar to be impacted and impacts of this

A
  1. Alveolar bone
  2. Soft tissue
  3. A tooth
  4. A combination of these
  • caries
  • pericoronitis
  • cyst formation
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4
Q

Incidence of impacted 3rd molars

A

36 - 59 %

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5
Q

Nerves at risk in M3M’s XLA

A
  1. Inferior alveolar (large risk)
  2. Lingual (medium risk)
  3. Long buccal (low risk)
  4. Mylohyoid (low risk)
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6
Q

Signs of inferior alveolar intimacy with M3M’s

A
  1. Interruption of corticated lines (lamina dura) of tooth or canal
  2. Darkening of root where crossed by canal
  3. Deflecting of IAC
  4. Deflecting of root
  5. Narrowing of IAC
  6. Narrowing of the root
  7. Dark and bifid root (wide apex opening)
  8. Juxta apical area (well defined radiolucency with corticated margins, lateral to root rather than apex = not pathology but meant to be a continuation of lamina dura and corticated margins of IAC canal) thus close proximity
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7
Q

Guidelines for XLA of wisdom teeth

A

NICE - guidance on extraction of wisdom teeth, 2000

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8
Q

Indications for XLA of third molars

A
  1. Undesirable Caries
  2. Acute severe single / Recurrent pericoronitis
  3. Periodontal disease
  4. Cysts
  5. Tumours
  6. External resorption of 6/7/8

Other reasons

  • orthognathic
  • medical indications prophylaxis (immunosuppressed, awaiting cardiac surgery, bisphosphonates antiangiogenics, chemotherapy, )
  • patient age / future ability to cope with tx
  • auto transplantation
  • g
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9
Q

What is pericoronitis

A

PE tooth with operculum, inflammation around crown

As communication distal to 7 with food packing etc (can be barely visible)

20-40 year olds commonly

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10
Q

Signs and symptoms of pericoronitis

A

Pain

Swelling

Suppuration

Bad taste

Bad breath

Dysphasia

Pyrexia

Malaise

Regional lymphadenopathy

Ulceration of operculum

Occlusal trauma to operculum

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11
Q

Predisposing factors for pericoronitis

A

White race

A full dentition

Insufficient space between ascending ramus and distal of 7

Poor OH

Stress and fatigue

Vertical / distoangular impaction

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12
Q

Treatment options for pericoronitis

A

Irrigation with warm saline water / chlorhexidine (anaphylaxis risk) with blunt needle

Analgesia advice

Dietary advice: Keep fluid levels up and eat soft food

Antibiotics*

If large extra oral swelling = maxfax urgent referral

Incision and drainage of abscess

XLA / coronectomy

Operculectomy

Surgical exposure (can allow to erupt)

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13
Q

When provide antibiotics for pericoronitis

A

Severe pericoronitis:

Systemically unwell

Swelling extra orally

Immunocompromised (I.e. diabetic)

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14
Q

What checking in OPT for XLA of third molars

A

Involvement of Sinus or IAN

Presence of disease

Anatomy for XLA (crown, root, condition)

Orientation of Impaction

Any associated pathology

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15
Q

Types of impaction of 3rd molars

A

Done by angulation compared to curve of spee

  • vertical (30 - 38%)
  • mesial (40%)
  • distal (6 - 15%)
  • horizontal (3 - 15%)
  • transverse (bucco lingual angulated) rare
  • aberrant (can be up the ramus / completely ectopic) rare
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16
Q

How are 3rd molars depths defined in surgical XLA planning

A

Superficial - crown only involved with crown of 7

Moderate - crown involved with crown and root of 7

Deep - crown only involved with root of 7

17
Q

Indications for NO XLA of 3rd molars

A

Symptomatic 8 with no associated disease ( consider other causes )
- TMD
- parotid disease
- lesions
- headaches
- referred angina pain
- oropharyngeal oncology

Asymptomatic with low disease risk
- just review at intervals

18
Q

Complications / risks post 3rd molar XLA (with % chance)

A

Pain
Bleeding
Swelling
Bruising
Infection
Jaw stiffness
Dry socket (osteitis)
Surgical procedure
Damage to adjacent teeth / rests.
Altered sensation (HYPO/HYPER/ana/para/dysaethesia)

IDN
- temporary 10-20%
- Permanent <1%

Altered taste from lingual nerve very rare
- temp 0.25-23%
- perm 0.14-2%

19
Q

How long for nerve damage from XLA is diagnosed as permanent

A

18-24 months, not going to heal

20
Q

Special investigation if PA shows close relationship between IAC and 8 to be XLA

A

Cone beam computed tomography (CBCT)

21
Q

Benefit of local anaesthetic in an XLA even if GA

A

Haemostasis easier

22
Q

How to cut flap for M3Ms XLA

A

Buccal mucoperiosteal flap

Can do lingual but risk lingual nerve damage

Larger flap heals just as fast

One continuous stroke with scalpel

Minimise trauma to dental papillae

23
Q

How to reflect surgical flap

A

Instruments

  • Mitchell’s trimmer
  • hearths periosteal elevator (holds out way)
  • ash periosteal elevator
  • curved Warwick James elevator (asking papillae flaps, others for while flap)

Raise from base of releasing incision

Full tissue done to bone

24
Q

How is bone removal facilitated for XLA

A

Electrical straight hand piece with saline cooled bur (surgical emphysema)

Round or fissure stainless steel and tungsten carbide burs

Round = remove bone
Fissure = separating tooth

Bone removal = buccal to distal

DEEP and NARROW gutter around tooth

work distal to medial as if slip = lingual nerve

25
Q

Types of tooth division for XLA of M3Ms

A

Horizontal
- NOT coronectomy as want enamel to grasp

Root division for XLA individually (vertical)
- if impacted so can’t XLA whole

ALWAYS cut distal to medial

26
Q

Types of debridement

A

Hard or soft tissues:

Physical
- handpiece / bone files
- soft tissue = Mitchell’s trimmer / Victoria curette)

Irrigation
- sterile saline

Suction
- aspirate under flap

27
Q

Aims of suturing following XLA and flap

A

Reposition tissue

Cover bone

Prevent wound breakdown

Achieve haemostats (compress Blood vessels)

Approximate tissue (don’t cover socket)

28
Q

Types of flap design for M3Ms XLA

A

3 sided flap (with medial releasing flap)

2 sided envelope flap (only distal releasing flap)

29
Q

Post op instructions for XLA

A

Careful with numbness not to bite self

Don’t touch area with finger, tongue or toothbrush

Don’t rinse mouth 6 hours after surgery / not that day

Warm salt mouth rinse 3-4 times daily (teaspoon of salt)

Cut down smoking for next week

Try not elevate heart rate for few days

Ice pack for swelling (wrapped in towel)

Over the counter analgesia

If pain worsens 2-3 days contact dentist

If antibiotics = finish

Contact us if swelling spreads, pus, numbness, jaw stiffness > 3 weeks

30
Q

Coronectomy procedure

A

Reduce chance of IAN damage

Transection 3-4mm bellow enamel and this distance bellow bone crest at least

Cut then elevate off

Pulp left

Irrigation then flap left open over XLA (some fully cover)

31
Q

Coronectomy follow up and warnings

A

Follow up
- review 1-2 weeks
- then 3-6m then 1 year
- radiograph at 6m-1y

Warnings
- if root mobilised, needs removed
- can get infection with roots left
- slow healing of painful socket
- may need XLA of roots if migrate to gingiva

32
Q

How to remove upper 8s

A

Usually very easy but can be very hard

Straight or curved Warwick James

Upper third molar bayonet forceps

SUPPORT tuberosity and if not budging will fracture this so only use forceps here

Can do buccal flap

🔵BDS4 Oral Surgery (4 decks)

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