Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BDS4 Oral Surgery > Third Molars > Flashcards

Third Molars Flashcards

1
Q

When do third molars erupt

A

18-24 years old

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

When do the upper third molar crowns begin calcification

A

7-9 years old

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

When do the lower third molars begin calcification

A

between 8-10 years old

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

When is root calcification of third molars complete

A

18-25

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the prevelance of agenesis of third molars

A

25%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is agenesis

A

where there is failure of development of the third molar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What jaw is agenesis more common in

A

upper
more common in females

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What gene is 3rd molar agenesis linked to

A

PAX9

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What age can we be confident that it is unlikely the third molars will develop

A

14

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What does impacted mean

A

molar can’t erupt to the functional position

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the most common reasons third molars fail to erupt

A

impaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the third molars impacted against

A

adjacent teeth (usually the 7) but can also be impacted against alveolar bone, surrounding mucosal soft tissue or a combination of these factors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

When is a tooth considered partially erupted

A

when some of the tooth has erupted into the oral cavity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the incidence of impacted mandibular third molars

A

36-59%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the common possible consequences of impacted mandibular third molars

A

o Caries
o Pericoronitis
o Cyst formation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the nerves in close proximity to the M3M

A

IAN
lingual
nerve to mylohyoid
long buccal nerve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What nerves are we most concerned about damaging with third molar surgery/extraction

A

IAN
lingual

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the IAN

A

Peripheral sensory nerve branching from the mandibular division of the trigeminal nerve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What does the IAN supply

A

All mandibular teeth
lower lip and chin up until the midline

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Where does the lingual nerve branch from

A

mandibular division of the trigeminal nerve

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What does the lingual nerve supply

A

Supplies the sensory anterior 2/3 of the dorsal and ventral mucosa of the tongue as well as a giving off a branch which supplies the lingual gingivae and floor of mouth
Carries fibers from the chorda tympani responsible for taste perception
Carries fibres responsible for secretory/motor innervation of sublingual and submandibular glands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Where does the lingual nerve lie

A

On the superior attachment of the mylohyoid muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Why is recovery of the lingual nerve slower than the IAN post-damage

A

As the IAN lies in a bony canal which can aid the healing and recovery whereas the lingual nerve is unsupported by bone and so recovery is slower

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Is it common for the lingual nerve to be close to the lingual plate

A

Yes, the lingual nerve has a close relationship to the lingual plate in the mandibular and retromolar area and in 15-18% of cases, the lingual is at or above the level of the lingual plate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Are there any pre-operative factors that can help predict risk of damage

A

 There aren’t any mentioned pre-operative factors related to lingual nerve injury, it is large due to surgical technique

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What do the 3 guidelines come from for M3M removal

A

NICE
SIGN
FDS, RCS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What are the NICE guidelines called

A

[o https://www.nice.org.uk/guidance/ta1/chapter/1-Guidance]
guidance on extraction of wisdom teeth 2000 (guidance being updated)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What was the general consensus from the NICE guidelines

A

This guidance discouraged the removal of third molars unless pathology was present such as caries, periodontal disease, infection or cyst

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is the name of the SIGN guidelines for M3M removal

A

SIGN publication number 43 – management of unerupted and impacted third molar teeth 2000

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What was the general consensus from the SIGN publication number 43

A

Provided similar guidance to NICE, removal of third molar should be justified and that is only the case when there is visible pathology

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is the name of the FDS, RCS guidelines regarding the M3M removal

A

[o https://www.rcseng.ac.uk/-/media/files/rcs/fds/guidelines/3rd-molar-guidelines–april-2021.pdf
FDS, RCS 2020 – Parameters of care for patients undergoing mandibular third molar surgery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What was the general consensus of the FDS, RCS guideliens

A

Guidance differs from that of NICE and SIGN

It encourages third molar removal more than the other 2 guidelines based on the premise that by not removing impacted third molars, inevitable surgery is being postponed and postponing this surgery makes the patient more prone to a more difficult surgical procedure

It therefore recommends changing from a simple therapeutic approach to a mixed range of interventions using a more holistic & informed approach

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Based on the FDS, RCS guidelines, what are the indications for extraction of M3M split into

A
  • therapeutic
  • surgical
  • medical
  • accessibility
  • age
  • autotransplantation
  • general anaesthetic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What are the therapeutic indications split into

A

infection
periodontal disease
cyst
tumour
external resorption of third molar/second molar

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What is teh most common indiciation for extraction of M3M

A

infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What types of infection may the M3M experience

A
  • pericoronitis
  • osteomyelitis
  • osteonecrosis
  • osteoradionecrosis
  • caries (M3M or adjacent teeth)
  • PA disease
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Why is periodontal disease an indication

A

Untreated horizontal mesioangular impaction (30 to 90 degrees) is prone to causing bone loss distal to the 7

Early extraction can prevent further periodontal damage of the 7

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What are symptoms of an M3M cyst

A

Generally no symptoms associated until they become large and infected

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What is the most common cyst experienced with M3M

A

The most common cyst to be found associated with impacted third molars are **dentigerous cysts **which are odontogenic cysts that surround the crown of an impacted tooth, caused by fluid accumulation between the reduced enamel epithelium and the enamel surface, resulting in a cyst which the crown is located within the lumen and root or roots outside

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

When would a tumour be an indication for removal of M3M

A

If the tumour is in close proximity to the lower 8 and they are to be undergoing radiotherapy, then can remove the 8 prior to treatment to prevent ORN post-treatment

May plan this for this who are to be administered bisphosphonates, risk vs benefit can be planned when considering prognosis of M3M & future risk of MRONJ

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What would be a surgical indication for removal of M3M

A

If present within the perimeter of a surgical field (orthognathic surgery, mandibular fracture management or resection of diseased tissue) then consider removal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What are medical indications of removal of M3M

A

o Have to make dentally fit for cardiac surgery etc
o Prevention of MRONJ, ORN may mean threshold for removal of third molars may be lowered
o Same principle for those on immunosuppressant therapy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

What are accessibility indications for removal of M3M

A

o Restricted access to dental service
o E.g army/long overseas trip

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Why is patient age an indication

A

o Complications + recovery time increase with age

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

What is autotransplanation

A

o Low success rate
o Uncommon
o Used to replace 6

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

When is GA an indication for removal of M3M

A

o If patient going for GA of one third molar, consider removing opposing/contralateral

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

What is pericoronitis

A

o Inflammation around the crown of a partially erupted tooth
o Tooth is normally partially erupted and visible but occasionally there may be very little evidence of communication and probing of the distal of the 7 will show a communication
o Food and debris can get stuck under the operculum resulting in inflammation or infection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

What types of microbes are involved in pericoronitis

A

anaerobes (streptococci, actinomyces etc)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

What are signs of pericoronitis

A

o Pain (throbbing)
o Swelling (can be intra or extra oral)
o Bad taste
o Pus discharge
o Occlusal trauma to operculum
o Ulceration of operculum
o Evidence of cheek biting
o Foeter oris (halitosis)
o Limited mouth opening
o Dysphagia

50
Q

How can pericoronitis result in dysphagia

A

Very rarely can get extra oral swelling to submandibular/sublingually which can impact swallowing

51
Q

What are the signs of systemic involvement in pericoronitis

A

o Pyrexia
o Malaise
o Regional lymphadenopathy

52
Q

What is treatent for pericoronitis

A

o Incision and drainage of localised pericoronal abscess if required with or without LA
o Irrigation with warm saline/CHX mouthwash (10-20ml syringe with blunt needle under operculum)
o Extraction if upper third molar traumatising operculum
o Patient instructed on frequent warm saline or CHX mouthwashes
o Advise use of analgesia
o Instruct to keep hydrated and keep eating

53
Q

When should a pericoronitis be referred to A/E

A

If large extra oral swelling, systemically unwell, trismus, dysphagia

54
Q

When should antibiotics be prescribed for pericoronitis

A

Do not prescribe AB unless severe pericoronitis, systemically unwell, extra-oral swelling, immunocompromised

55
Q

Why are operculectomy not done very often anymore

A

operculum grows back

56
Q

Why are operculectomy not done very often anymore

A

operculum grows back

57
Q

What are the predisposing factors to pericoronitis

A

o Partial eruption and vertical or distoangular impaction
o Opposing maxillary 8 or 7 causing mechanical trauma contributing to recurrent infection
o Upper respiratory tract infections as well as stress and fatigue
o Poor oral hygiene
o Insufficient space between ascending ramus of lower jaw and distal aspect of the 7
o White race
o Full dentition

58
Q

What should we look at in an extra-oral examination

A

o TMJ
o Limited mouth opening
o Lymphadenopathy
o Facial symmetry
o Muscles of mastication

59
Q

Why is the TMJ important for M3M pain

A

TMJ pain can be mistaken for pain of pericoronitis as TMJ pain can be periauricular

60
Q

What do we look at for intra oral examination

A

o Soft tissue examination
o Dentition
o Health of the 7
o Eruption status of the mandibular third molar
o Occlusion
o Oral hygiene
o Caries status
o Periodontal status

61
Q

When should we take a radiograph of the M3M

A

Only taken if surgical consideration considered, don’t take one if patient sure they don’t want the tooth out

62
Q

What do we determine from the OPT

A

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

63
Q

Why do we look at the follicular width on an OPT

A

Studies suggest that if the width of the follicle is greater than 3mm then this is suspicious of pathology

64
Q

What is the Rood & Shehab paper about

A

produced a paper that give indications of radiological prediction of inferior alveolar nerve injury during third molar surgery

65
Q

What increases the likelihood of third molar/IAN relationship

A

if the molar is impacted

66
Q

What are the Rood and Shehab signs

A
  • darkening of the root
  • deflected roots
  • narrowing of the root
  • dark and bifid root
  • interruption of the white lines
  • diversion of the inferior alveolar canal
  • narrowing of the inferior alveolar canal
67
Q

What is a normal root density

A

Usually the density of the root is the same throughout its length and this is not disturbed when the images of the tooth and inferior alveolar canal overlap

68
Q

Why does the root appear darker when the IAN is related to the M3M

A

When there is impingement of the canal on the tooth root, there is loss of density of the root and the root appears darker

Darkening of the root is attributed to the decreased amount of tooth substance or loss of the cortical lining of the canal between the source of X-rays and the film

69
Q

What are deflected roots

A

Deflected roots or roots hooked around the canal are seen as an abrupt deviation of the root when it reaches the inferior alveolar canal
The root may be deflected to the buccal or lingual side or to both sides so that it completely surrounds the canal or it may be deflected to the mesial or distal aspect

70
Q

What does narrowing of the roots imply

A

If there is narrowing of the root where the canal crosses it, it implies that the greatest diameter of the root has been involved by the cnala or there is deep grooving or perforation of the root

71
Q

What does dark and bifid root indicate

A

Appears when the inferior alveolar canal crosses the apex
Is identified by the double periodontal membrane shadow of the bifid apex

72
Q

What are the white lines referred to by Rood and Shebab

A

White lines are the 2 radiopaque lines that constitute the roof & floor of the canal
These lines appear on a radiograph due to the dense structure of the canal walls

73
Q

When are the lines considered interrupted

A

The white line is considered to be interrupted if it disappears immediately before it reaches the tooth structure
One or both white lines may be involved

74
Q

What does interruption of the white lines indicate

A

The interruption of the white line is considered to indicate deep grooving fo the root if it appears alone or perforation of the root if it appears with the narrowing of the canal

75
Q

When is a canal considered to be diverted

A

Canal is considered to be diverted if when it crosses the mandibular third molar, it changes direction

76
Q

Why is the inferior alveolar canal diverted

A

An upward displacement of the canal to the contents of the canal passing through the root and hence during eruption of the third molar, the contents are dragged upwards with it

77
Q

When is the inferior alveolar canal considered narrow

A

Considered narrow if, when it crosses the root of the mandibular third molar, there is a reduction of its diameter

78
Q

Why does the inferior alveolar canal narrow

A

narrowing could be due to the downward displacement of the upper border of the canal or the displacement of the upper and lower borders towards each other with the hour glass appearance

79
Q

What does an hourgalss form of the IAC indicate

A

encirclement of the canal or a complete encirclement

80
Q

Which Rood and Shehab signs are associated with significantly increased risk of nerve injury during M3M surgery

A

o Diversion of the inferior dental canal
o Darkening of the root where it crosses the canal
o Interruption of the white lines of the canal

81
Q

What is another sign of close relationship of the IAC & M3M that isn’t mentioned by rood and shehab

A

Juxta apical area

This will appear as a well circled radiolucent region lateral to the root of the third molar but not at the apex
Not pathological

82
Q

What

A
83
Q

How do we measure angulation if impaction

A

measured against curve of spee

84
Q

What are the types of angulation

A

o Vertical
o Mesial
o Distal
o Horizontal
o Transverse or aberrant

85
Q

What are the most common types of impaction

A

Vertical & mesial are most common

86
Q

What does the depth of impaction give an indication of

A

amount of bone removal required

87
Q

How would superficial impaction be

A

crown of the 8 related to the crown of the 7

88
Q

How would moderate impaction be

A

crown of the 8 related to the crown + root of the 7

89
Q

What would deep impaction be

A

crown of 8 related to the root of the 7

90
Q

What are common treatment options for M3M

A

o Referral
o Clinical review
o Removal of M3M
o Extraction of third molar
o Coronectomy

91
Q

What are common options for M3M

A

o Operculectomy
o Surgical exposure
o Pre-surgical orthodontics
o Surgical reimplantation/autotransplantation

92
Q

When we consider GA for M3M surgery

A

 Extreme anxiety
 Extensive surgery
 Sedation contraindicated
 Genuine LA allergy

93
Q

What type of consent is required for GA / IV sedation

A

written
although written always best practice

94
Q

What are the risks of surgery/extraction of M3M

A

usual big 5
restoration fracture of adjacent tooth
mandibular fracture
anaesthesia
parasthesia
dysaesthesia
hypoaesthesia
heightened sensation

95
Q

What are the big 5

A

pain, swelling, bruising, bleeding, infection

96
Q

What predisposes a patient to mandibular fracture

A

 Edentulous/atrophic mandible
 Aberrant lower 8 close to lower border of mandible
 Large cystic lesion associated with wisdom tooth
 Would be fixed at later date in oral max fax

97
Q

If there are concerns on the proximity of the IDC and the roots from the x-ray, what should the px be offered

A

CBCT

98
Q

How is access gained

A

buccal mucoperiosteal flap
can be 3 sided flap or envelope

99
Q

What is a mucoperiosteal flap

A

A mucoperiosteal flap includes the surface mucosa, submucosa and the periosteum, this shows clean bone and avoids unnecessary trauma to the underlying tissues which would delay healing
Importance placed on minimising trauma to interdental papillae

100
Q

Why should the reflection be firmly on bone

A

 Avoid dissection occurring superficial to periosteum
 Reduce soft tissue bruising/trauma

101
Q

What tissues are difficult tissues to reflect with minimal trauma

A

papilla
mucogingival junction

102
Q

What instruments are used for reflection

A

 Mitchell’s trimmer
 Howarth’s periosteal elevator
 Ash periosteal elevator
 Curved Warwick James (used to reflect the papillae)

103
Q

What is the aim of retraction

A

o Allows access to operative field
o Protects the soft tissue from falling back and getting caught in the bur

104
Q

What instruments are used for retraction

A

 Periosteal elevator
 Rake retractor
 Minnesota retractor

105
Q

What is used to remove bone

A

Electrical straight handpiece with saline cooled bur is used
Round or fissure stainless steel burs & tungsten carbide burs used

106
Q

Why must the handpiece be electric

A

as introduction of air into these tissues can result in surgical emphysema

107
Q

Where is bone removal carried out

A

On buccal aspect of the tooth and onto the distal aspect of impaction

Buccal gutter should be started at the distal round to the mesial as allows more control of the bur and decreases risk of soft tissue damage/lingual nerve damage

108
Q

What is the aim of bone removal

A

to create a deep, narrow gutter around the crown of the wisdom tooth to allow correct application of elevators on the mesial and buccal aspects of the tooth

There should be plenty of irrigation to maintain visibility and avoid bony necrosis

109
Q

How is the tooth removed

A

either as whole or sectioned
whole if possible is best, with elevators and forceps

110
Q

How can the tooth be divided

A

crown sectioned from roots
seperate crown, then seperate roots
vertically sectioned, both crown and roots

111
Q

If the crown is divided from the roots, how should this be done

A

want to section the crown above the ACJ as this leaves some crown behind which allows for orientation and elevation

different from coronectomy where crown would be removed below the ACJ

112
Q

What is the function of debridement post removal

A

any debris must be cleaned out and any follicular tissue or granulation tissue from chronic infection should be curetted, especially hidden behind the second molar

113
Q

What are the types of debridement

A

physical
irrigation
suction

114
Q

What is used to phsyically debride

A

 Use a bone file/handpiece to remove sharp bony edges
 Use a mitchell’s trimmer/Victoria curette to remove soft tissue debrirs

115
Q

What is the function of suction in debridement

A

Aspirate under flap to remove debris, this must be done before the flap is repositioned
Check socket for retained apices

116
Q

What is the function of suturing

A

o Approximates tissues + compresses blood vessels

117
Q

What are the aims of suturing

A

 Reposition
 Cover bone
 Prevent wound breakdown
 Achieve haemostasis

118
Q

What is coronectomy

A

o Alternative to surgical removal of entire tooth when there appears to be an increased risk of IAN damage with surgical removal
o The crown is removed with the deliberate retention of the roots adjacent to the IAN

119
Q

What is the technique for coronectomy

A

o Similar access is required
o Transection of the tooth 3-4mm below ACJ
o Elevate/lever crown off without mobilising the roots
o Pulp left in place untreated
o If necessary, reduction of roots with a rose head bur to 3-4mm below alveolar crest
o Socket irrigated
o Flap replaced

Then follow up

120
Q

When should the patient be followed up

A

 Review 1-2 weeks
 Further review 3-6 months then 1 year
 Some review at 2 years but most discharge back to GDP after 6 months/1 year review
 Radiographic review 6 months or 1 year or both
 After this, only radiograph if symptomatic
 Some take an immediate or 1 week post-op x ray

121
Q

What are the warnings for coronectomy

A

 If root is mobilised during crown removal then entire tooth must be removed, its more likely with conical fused roots
 Leaving roots behind could result in infection although rare which would require further procedure
 Can get a slow healing/painful socket, similar to dry socket
 Roots may migrate later and begin to erupt through the mucosa and may require extraction

BDS4 Oral Surgery (15 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions