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FINALS - Oral Surgery > Third Molars > Flashcards

Third Molars Flashcards

1
Q

Which nerves are at risk during third molar surgery?

A

Inferior Alveolar Nerve
Lingual Nerve
Nerve to Mylohyoid
Long Buccal Nerve

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2
Q

Describe the development of third molars.

A

Third molars usually erupted into the mouth between 18-24y
Crown calcification begins 7-10y and is completed age 18y
Root calcification complete between 18-25y
1 in 4 adults will find that they have at least 1 third molar missing
If missing at age 14 on radiograph, almost always fail to develop

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3
Q

What does impacted mean?

A

The eruption of the tooth is blocked, not necessarily an indication for surgery.

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4
Q

What is the incidence of third molars?

A

M3M’s are usually impacted against adjacent tooth, alveolar bone, surrounding mucosal soft tissue or a combination of these factors.

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5
Q

What are the common consequences of impacted third molars?

A

Consequence of impaction can be caries, pericoronitis or cyst formation.

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6
Q

What is the average distance between the mandibular bone and the lingual nerve?

A

Average is 3.45mm, but can be as close as 0.5mm.

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7
Q

What is meant by the term agenesis?

A

The failure of an organ to form.

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8
Q

Which guidelines are used to direct third molar surgery?

A

NICE- Guidance on Extraction of Wisdom Teeth, 2000

SIGN Publication Number 43 – Management of Unerupted and Impacted Third Molar Teeth, 2000

FDS, RCS 2020 - Parameters of Care for patients undergoing mandibular third molar surgery

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9
Q

What are the indications for extraction of a third molar?

A

Infection (caries, pericoronitis, periodontal disease or local bone infection) – most common, but also cysts and tumors

External resorption of 7 or 8

Surgical indications ie within surgical field

High risk of disease

Medical indications egawaiting cardiac surgery, immunosuppressed or to prevent osteonecrosis
Accessibility- limited access

Patient age- complications and recovery time increase with age

Autotransplantation

General Anesthetic

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10
Q

What is pericoronitis?

A

Inflammation around the crown of a partially erupted tooth, resulting from food & debris getting trapped under the operculum resulting in inflammation or infection.

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11
Q

Which microbes are commonly found in pericoronitis?

A

Anaerobic microbes (Streptococci , Actinomyces, Fusobacterium)

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12
Q

Describe the inferior alveolar nerve?

A

A peripheral sensory nerve stemming from V3, entering through the mandibular foramen and providing sensory innervation to the lower teeth, periodontal tissue, and mental nerve.

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13
Q

List the signs and symptoms of pericoronitis.

A

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

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14
Q

What management options are there for pericoronitis?

A

Incision of localized pericoronal abscess if required

+/- local anesthetic (IDB) – depends on pain/patient

Irrigation with warm saline or chlorhexidine mouthwash (10-20ml syringe with blunt needle – under the operculum).

Extraction of upper third molar if traumatizing the operculum

Patient instructed on frequent warm saline or chlorhexidine mouthwashes
Advice regarding analgesia

Instruct patient to keep fluid levels up and keep eating (soft/liquid diet if necessary)

Generally do not prescribe antibiotics unless more severe pericoronitis, systemically unwell, extra-oral swelling, immunocompromised e.g. diabetic

If large extra-oral swelling, systemically unwell, trismus, dysphagia – refer to maxillofacial unit or A&E

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15
Q

What predisposing risk factors are there for pericoronitis?

A

Partial eruption and vertical or distoangular impaction

Opposing maxillary M3M or M2M causing mechanical trauma contributing to recurrent infection

Upper respiratory tract infections as well as stress and fatigue pericoronitis

Poor oral hygiene

Insufficient space between the ascending ramus of the lower jaw and the distal aspect of the M2M

White race

A full dentition

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16
Q

What aspects of a patients history should be considered for assessing third molar issues?

A

General Appearance

Presenting complaint eg recurrent pericoronitis

History of Presenting Complaint –how long, how many episodes, how often, severity, requirement for antibiotics?

Medical History – systemic enquiry, Medications, Allergies, Previous hospitalizations inc surgery

Dental History – history of extractions, dental anxiety, dental experience, regular oral hygiene

Social History – smoking, alcohol, occupation, carer, support

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17
Q

List the extra-oral features you would look at when assessing third molar issues?

A

TMJ
Limited mouth opening
Lymphadenopathy
Facial asymmetry
Muscles of Mastication

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18
Q

List the intra-oral features you would look at when assessing third molar issues?

A

Soft Tissue examination
Dentition
M2M
Eruption status of the M3Ms
Condition of the remaining dentition
Occlusion
Oral hygiene
Caries status
Periodontal status

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19
Q

What information can be gained from an OPT when considering third molar surgery?

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 lower third molars inferior dental canal
Any other associated pathology

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20
Q

List the radiographic signs that there is a close relationship between the apex of the third molar and the inferior alveolar nerve?

A

Interruption of the white lines/lamina dura of the canal
Darkening of the root where crossed by the canal
Diversion/deflection of the inferior dental canal
Deflection of root
Narrowing of inferior dental canal
Narrowing of the root
Dark and bifid root
Juxta apical area

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21
Q

Which paper outlines the radiographic features of a potentially high risk third molar extraction (in relation to the inferior alveolar nerve)?

A

Rood and Shehab (1990)

22
Q

What are the two most common angulations of impacted third molars?

A

Mesial and vertical impaction.

23
Q

How would you classify the depth of a third molar?

A

Superficial, moderate, or deep
Compare the crown of the 8 compared to root of the 7

24
Q

List the possible angulations of an impacted third molar/

A

Mesially
Distally
Transverse (B-L or L-B)
Aberrant (way out of place)

25
Q

What are the treatment options for third molars causing problems?

A

Common:
Referral
Clinical review
Removal of M3M
Extraction of maxillary third molar
Coronectomy

Less common:
Operculectomy
Surgical exposure
Pre-surgical orthodontics
Surgical reimplantation/ autotransplantation

26
Q

What aspects should be explained to the patient to obtain informed consent for a third molar surgery?

A

Explain procedure to patient

If tooth is likely to need sectioned explain this

Give the patient an idea of what to expect during the procedure

Explain minor surgical procedure, flap, possible drilling, sutures

Risks of treatment and risks of not treating.

+/- Sedation or GA

27
Q

When should you explain the risk of jaw fracture from lower third molar extraction?

A

In edentulous/atrophic mandible, aberrant lower 8 close to lower border of mandible, large cystic lesion associated with wisdom tooth - explain risk of jaw fracture.

28
Q

What is the risk of nerve damage to the IDN when extracting a lower third molar?

A

Temporary numbness/dysesthesia
10-20% will experience this (literature suggests range:2.7 – 36)

Permanent numbness/dysesthesia
<1% will experience this (Literature quotes 0.2 – 3.6%)

29
Q

What is the risk of nerve damage to the lingual nerve when extracting a lower third molar?

A

Temporary numbness/dysesthesia:
0.25-23% will experience this

Permanent numbness/dysesthesia:
0.14-2% will experience this

30
Q

After what period are nerves unlikely to recover from damage?

A

Can take 18-24 months to recover, but after that period it is unlikely.

31
Q

Outline the steps involved in raising a buccal mucoperiosteal flap to access a third molar?

A

Access to the tooth is gained by raising a buccal mucoperiosteal flap

+/- raising a lingual flap (some debate/depends on surgeon and the clinical situation)

Maximum access with minimal trauma

Larger flaps heal just as quickly

Use scalpel in one firm continuous stroke

Minimise trauma to dental papillae

General principals of flap design

32
Q

Which instruments can be used to aid in raising a flap?

A

Mitchell’s trimmer

Howarth’s periosteal elevator

Ash Periosteal Elevator

Curved Warwick James elevator

33
Q

Which two parts of the anatomy are generally the most difficult to reflect when raising a flap and why?

A

Papilla
mucogingival junction

They require reflection with minimal trauma, for better healing outcome.

34
Q

How deep should a flap incision be?

A

Down to the periostium, resting in firmly on bone.

35
Q

What handpieces and burs should be used for bone removal, and why?

A

Electrical straight handpiece with saline cooled bur

Air driven handpieces may lead to surgical emphysema

Round or fissure stainless steel & tungsten carbide burs

36
Q

Outline the main principles of bone removal to remove a wisdom tooth?

A

It is carried out on the buccal aspect of the tooth and onto the distal aspect of the impaction

The intention is to create a deep, narrow gutter around the crown of the wisdom tooth

Not a shallow, broad gutter

Bone should be removed to allow correct application of elevators on the mesial and buccal aspects of the tooth

37
Q

Why is good irrigation required when removing bone?

A

Maintains visibility and avoids necrosis of the bone.

38
Q

When should bone removal be considered for wisdom tooth surgery?

A

The operator must then assess the possibility of removing the tooth in its entirety with elevators or a combination of elevators and forceps

If this is not possible and adequate bone has been removed the tooth should then be sectioned with the drill/burs

39
Q

Describe the possible methods of tooth division for surgical removal of wisdom teeth?

A

Most commonly the crown of the tooth is sectioned from the roots and the crown and roots are elevated as individual items

Sometimes further separation of the roots with a bur is required following elevation of the crown, and each root is elevated as an individual item

Can be between crown and root, or along the axis of the tooth. (Horizontal or vertical)

40
Q

Describe the difference in sectioning a tooth in a coronectomy and complete extraction?

A

When sectioning for coronectomy you should section above the CEJ, to allow for elevation and orientation.

When sectioning for coronectomy you should section below the CEJ to allow for the maximum amount of tooth removal.

41
Q

What are the benefits of sectioning a tooth vertically when extracting a wisdom tooth?

A

Allows for removal of distal portion of the tooth, making more space for the mesial portion.

42
Q

Describe the possible suture placements for a three sided flap for a wisdom tooth surgery.

A

Distal of the socket running B-L

Mesial of the socket running from the papilla to B of the 7
(May require second suture lower on the incision)

+/- Running mesial of the socket running papilla to papilla

43
Q

Describe the possible suture placements for an envelope flap for a wisdom tooth surgery.

A

Distal of the socket running B-L

Running mesial of the socket running papilla to papilla

44
Q

What is a coronectomy and what is the purpose of it?

A

Alternative to surgical removal of entire tooth when there appears to be an increased risk of IAN damage with surgical removal

Aim – to reduce the risk of IAN damage

The crown is removed with the deliberate retention of the root adjacent to the IAN

45
Q

Describe the process of a coronectomy.

A

Flap design as necessary to gain access to tooth. Generally – standard wisdom tooth flap designs

Transection of tooth 3-4mm below the enamel of the crown into dentine

Elevate/lever crown off without mobilising the roots

Pulp left in place – untreated

If necessary – further reduction of roots with a rose head bur to 3-4mm below alveolar crest (not always possible)

46
Q

What should you warn the patient of before performing a coronectomy?

A

If the root is mobilised during crown removal the entire tooth must be removed (more likely with conical fused roots)

Leaving roots behind could result in infection (rarely seen)

Can get a slow healing/painful “socket”

The roots may migrate later and begin to erupt through the mucosa; and may require extraction

47
Q

List some considerations when removing upper wisdom teeth.

A

Support the tuberosity with finger and thumb

If there is undue resistance to elevation/extraction then excessive force can fracture the tuberosity – the use of forceps and support to the tuberosity should reduce this risk in these circumstances

If it is not possible to get access to the partially erupted upper third molar a buccal flap may be raised and appropriate bone removal carried out.

48
Q

What are the sign guidelines for not advising removal of wisdom teeth?

A

In patients whose 3rd molar would be judged to erupt successfully and
have functional role in dentition

In patients whose medical history renders the removal an unacceptable risk

In patients with deeply impacted 3rd molars with no history or evidence of pertinent local or systemic pathology

In patients where the risk of surgical complications is judged to be unacceptable high or where fractures of an atrophic mandible may occur

Where surgical removal is planned under LA the simultaneous extraction
should not be undertaken.

49
Q

What are the strong indications for removal of wisdom teeth?

A

1 or more episodes of pericoronitis, cellulitis, abscess formation or periapical pathology

When caries/periodontal disease occurs and is present in 7s and cannot be reached without removing 8s

Cases of dentigerous cysts formation and other pathologies

In fractured mandible cases when the 3rd molar is involved

When an unerupted 3rd molar is in an atrophic mandible

For autogeneous transplantation

Cases of ERR of 3rd molar or 2nd molar caused by wisdom tooth

Partially erupted or unerupted 8 close to alveolar surface prior to
denture construction or close to a planned implant

50
Q

What is assessed during radiological assessment when removing 3rd
molars?

A

Angulation/orientation of impaction

Crown size and condition – shape, size and caries status

Root number, length, morphology and presence of apical hooks

Alveolar bone level including depth and point of elevation and density

Follicular width

Periodontal status of 3rd molar and adjacent tooth

o Relationship and proximity to maxillary antrum and IAN
o Any associated pathologies – dentigerous cysts, loss of bone distal to crown due to pericoronal infections

Assess risk of nerve damage

51
Q

List the potential post operative complications of wisdom tooth surgey.

A

Pain, swelling, bruising, bleeding, jaw stiffness

Infections

Dry socket (alveolar osteitis)

Dysaesthesia – painful, uncomfortable sensation of lower lip, chin and tongue

Altered taste

Numbness (anaesthesia) or tingling (paraesthesia) of lower lip, chin and side of tongue

52
Q

List the possible risk factors for pro-longed bleeding.

A

Medical conditions – haemophilia A/B, Von willebrand disease, liver disease/cirrhosis

Medications – warfarin, anticoagulants

Llifestyle – alcoholic

FINALS - Oral Surgery (14 decks)

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