Third Molars Flashcards

(39 cards)

1
Q

At what age do third molars usually erupt?

A

between 18 and 24

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

when does crown calcification of third molars begin and end?

A

begins 7-10
completed by age 18

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

when does root calcification complete in third molars?

A

18-25

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

what proportion of adults have at least one third molar missing?

A

1 in 4
- more common in maxilla and females
- almost always fail to develop if missing at 14 in radiograph

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

impacted third molars - what does this mean?

A

tooth eruption is blocked

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

What are mandibular third molars usually impacted against?

A

adjacent tooth
alveolar bone
surrounding mucosal soft tissues
a combination of these factors

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

incidence of impacted lower third molars

A

36-59%

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

consequences of impacted third molars

A

caries
pericoronitis
cyst formation

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

what nerves are at risk during mandibular third molar surgery?

A

inferior alveolar
lingual
nerve to mylohyoid
long buccal

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

indications for extracting third molars

A

infection
- caries
- pericoronitis
- periodontal disease
- local bone infection
cysts
tumour
external resorption of 7 or 8
high risk of disease
medical indications e.g.g immunosuppressed
accessibility
autotransplantation

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

what is pericoronitis?

A

inflammation around the crown of a partially erupted tooth

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

how does pericoronitis occur?

A

food and debris gets trapped in the operculum resulting in inflammation and infection

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

what type of microorganisms are responsible for periocoronitis?

A

anaerobic microbes
e.g. streptococci, actinomyces, fusobacterium

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

pericoronitis signs and symptoms

A

pain
swelling
bad taste
pus discharge
ulceration of operculum
evidence of cheek biting
limited mouth opening
dysphagia
malaise
regional lymphadenopathy

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

pericoronitis treatment

A

incision of localised pericoronal abscess if present
- LA IDB - depends on pain/patient
irrigation with warm saline or chlorhexidine mouthwash (10-20ml syringe with blunt needle under the operculum)
XLA of upper third molar if traumatising the operculum
patient instructions on frequent warm saline or chlorhexidiene mouthwashes

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

pericoronitis - instructions to give patient

A

analgesia
instruct patient to keep fluid levels up and keep eating
- soft diet if necessary
generally do not prescribe antibiotics unless more severe case, systemically unwell, e/o swelling or immunocompromised e.g. diabetes
if large e/o swelling, scenically unwell, trsimus or dysphagia - refer to max fax or A&E

17
Q

pericoronitis predisposing factors

A

partial eruption and vertical or distoangular impaction
opposing maxillary 2nd or 3rd molar causing mechanical trauma contributing to recurrent infection
poor oH
insufficient space between ascending ramus of lower jaw and distal aspect of mandibular 2nd molar
white race
full dentition

18
Q

XLA 3rd molars - radiographic examination features

A

only if surgical intervention is being considered
OPT to determine
- presence or absence of disease
- depth and orientation of impaction
working distance
periodontal status
any associated pathology
relationship of upper third molars to maxillary sinus or lower third molars to inferior dental canal

19
Q

radiographic signs which may indicate close proximity of the root and the IAN

A

diversion of the inferior dental canal
darkening of the root where crossed by the canal
interruption of the white lines of the canal
deflection of root
narrowing of inferior dental canal
dark and bifid root
narrowing of the root

20
Q

3 radiographic signs associated with a significant increased risk of nerve injury during third molar surgery

A

diversion of the inferior dental canal
darkening of the root where crossed by the canal
interruption of the white lines of the canal

21
Q

What other imaging is possible if conventional imaging has shown a close relationship between the third molar and the inferior dental canal?

22
Q

post operative complications of third molar surgery

A

pain
swelling
bruising
jaw stiffness/limited mouth opening
bleeding
infection
dry socket

23
Q

what percentage of patients may experience temporary numbness or parasthesia to the lower lip/chin following lower third molars extraction?

A

10-20%
may take weeks or months to improve
< 1% permanent

24
Q

surgical extraction - steps

A

anaesthesia
access
bone removal as necessary
tooth division
debridement
suture
achieve haemostasis
post op instructions

25
surgical removal - anaesthesia options
LA IV sedation and LA general anaesthetic
26
how is access gained during a surgical extraction
mucoperioesteal flap is raised - lingual flap may also be raised use scalpel in one firm continuous stroke
27
surgical removal - reflection
rinse flap at base of relieving incision reflect with periosteal elevator firmly on bone
28
surgical removal - retraction principles
access to operative field protection of soft tissues atraumatic/passive retraction - rest firmly on bone - awareness of adjacent structures e.g. mental nerve
29
surgical extraction - bone removal
electrical straight handpiece with saline cooled bur used - as air driven handpicks may cause surgical emphysema round or fissure stainless steel and tungsten carbide burs used bone removal carried out on buccal aspect of tooth and onto distal aspect of impaction intention is to create a deep narrow gutter around the corn of the wisdom tooth bone should be removed to allow correct application of elevators on the mesial and buccal aspects of the tooth
30
how is tooth division done?
most commonly - crown of tooth is sectioned from the roots crown and roots are elevated as individual items - sometimes further of separation of roots is required following elevation of the crown
31
When sectioning to remove the entire tooth section, why should you remove the crown at just above the ACJ?
leaves some crown behind allowing orientation and elevation
32
surgical removal - debridement
physical - bone file or handpiece to remove sharp bony edges - Mitchell's trimmer or Victoria curette to remove soft tissue debris irrigation - sterile saline into socket and under flap - must irrigate below flap before repositioning suction - aspirate under flap to remove debris - check socket for retained apices
33
aims of suturing
reposition tissues cover bone prevent wound breakdown achieve haemostasis
34
what is a coronectomy?
removal of the crown of the tooth with deliberate retention of root adjacent to the inferior alveolar nerve alternative to surgical removal of entire tooth where there appears to be an increased risk of IAN damage with surgical removala
35
aims of a coronectomy
to reduce risk of damage to inferior alveolar nerve
36
coronectomy steps
flap design as necessary to gain access transection of tooth 3-4mmm below crown elevation of crown without mobilising roots socket irrigated flap replaced
37
coronectomy follow up
review in 1-2 weeks further 3-6 monthly review then 1 year radiographic review - 6 months or 1 year or both - some take immediate or 1 week post op radiograph
38
coronectomy - warnings to patient prior to procedure
if root is mobilised during crown removal the entire tooth must be removed leaving roots behind can result in infection (rare) can get a slow healing/painful 'socket' roots may migrate later and begin to erupt through mucosa - may require extraction
39
upper third molar extraction - things to take care with when extracting
support tuberosity with finger and thumb if access difficult a buccal flap can be raised followed by appropriate bone removal