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BDS4 CDS Oral Surgery > Third Molars 1 > Flashcards

Third Molars 1 Flashcards

1
Q

3rd molars extracted where

A

referred to speciliast/hospital

rare to extract in practice

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2
Q

third molar surgery one of the most common surgerys performed by NHS

true or false?

A

true

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3
Q

eruption period for third molars

A

18-24y

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4
Q

crown calcification of third molars

A

begins 7-10y and completed by 18y

7-9 for upper
8-10 for lower

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5
Q

root calcification for third molars

A

18-25y

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6
Q

how many adults have at least one third molar missing?

A

1 in 4 adults

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7
Q

agenesis

A

failure of an organ to development

e.g. third molar

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8
Q

common site for missing third molar development

A

maxilla

more in females

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9
Q

what age can be presumed if third molars are missing on radiograph that they will never develop

A

14

but can erupt at any age (sometimes get 50+ coming in due to denture rocking or pain and 3rd molar is erupting)

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10
Q

impacted means

A

tooth eruption is blocked

descriptive term
not indicative of surgery

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11
Q

most common reason why third molars fail to erupt

A

impacted

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12
Q

what can mandibular third molars be impacted against

A

adjacent tooth
alveolar bone
surrounding mucosal soft tissue

or combination of these factors

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13
Q

options for eruption for impacted M3Ms

A

unerupted
partially erupted
fully erupted

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14
Q

partially erupted

A

when some of the tooth has erupted into the oral cavity

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15
Q

unerupted

A

when the tooth is completely buried (in bone and soft tissue)

can still sometimes have a communication beetween bacteria and oral cavity and tooth
* caries evident on radiograph, despite not being able to see it clincally

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16
Q

incidence of impacted lower third molars

A

36-59%

17
Q

consequences of impacted lower third molars

3

A

caries
pericoronitis
cyst formation

18
Q

cyst formation from lower third molars

A

due to failure of the follicle around the crown of tooth not separating

19
Q

nerves at risk during M3M surgery

4

A

**inferior alveolar nerve
lingual nerve **

nerve to mylohyoid
long buccal nerve

20
Q

inferior alveolar nerve

what is it

A

peripheral sensory nerve from mandibular branch of trigeminal nerve

21
Q

inferior alveolar nerve

supplies

A

all mandibular teeth on that side and mucosa, skin of lower lip and chin on that side

22
Q

inferior alveolar nerve

position

A

varies greatly from person to person

in a bony cavity
OPT best to see (may need CBCT)

23
Q

lingual nerve

branch of

A

mandibular division of trigeminal nerve

24
Q

lingual nerve

supplies

A

anteiror 2/3 of dorsal and ventral mucosa of tongue
has branch which supplies lingual gingivae and FOM

25
Q

lingual nerve

position

A
  • Close relationship to lingual plate in mandibular and retromolar area
  • At or above level of lingual plate in 15% - 18% of cases
  • Between 0 – 3.5mm medial to the mandible
26
Q

Guidelines role

A

help make clinical decisions based on evidence

27
Q

old Guidelines for third molar surgery

A

NICE- Guidance on Extraction of Wisdom Teeth, 2000
* National institute for health and care excellence
* Discourage removal unless pathology in them

SIGN Publication Number 43 – Management of Unerupted and Impacted Third Molar Teeth, 2000
* Scottish intercollegiate guidance network
* Due to risks, need to be able to justify removal (caries, infection, perio, cysts)

28
Q

current used guideline for third molar surgery

A

FDS, RCS 2020 - Parameters of Care for patients undergoing mandibular third molar surgery
Most up to date
* Consensus document (not systematic review), based on evidence and multidisciplinary review, taking into account views from all disciplines and range of best practice from healthcare providers
* Mixed range of interventions based on more holistic, need agreed by pt
* If leave – cause disease, hard to remove when decay, pt older = more complications

29
Q

indications for extractions of third molars

8

A
  • therpeutic indications
  • surgical indications* i.e. within surgical field (orthognathic, fractured mandible, in resection of diseased tissue)*
  • high risk of disease -mesial angular or horizontal impaction meaning limited access for OH
  • medical indications e.g. awaiting cardiac surgery, immunosuppressed or to prevent osteonecrosis
  • accesibility - limited access to dentist (work abroad, oil rigs etc)
  • pt age -* complications and recovery time inc with age *
  • autotransplantation (rare, to first molar)
  • general anaesthetic -* remove opposing or contralateral at same time, to reduce further GA*
30
Q

therapeutic indications for extractions of third molars

4

A

Infection
* most common = caries, pericoronitis, periodontal disease or local bone infection
* periodontal – mesial angular impaction prone to bone loss distal to lower 7, later removal – inc perio damage

Cysts
* Most common is dentinogenous cyst (reduced enamel epithelium separation from crown), more mandible than maxilla (10x)

Tumours
* Prevent ORN, part of resection

External resorption of 7 or 8
* Destruction of tissue, cause unclear, progressive, 21-30y

31
Q

pericoronitis

A

inflamation around the crown of partially erupted tooth

tooth is normally partially erupted and visible – but occasionally there may be very little evidence of the communication and careful probing distal to the second molar is required to show that there is a small communication

Food & debris gets trapped under the operculum resulting in inflammation or infection

32
Q

pericoronitis

features

A

Usually transient and self-limiting

Usually occurs 20-40 years

General health not related to incidence of pericoronitis, except upper respiratory tract infection (start as URTI then develop pericoronitis)

Second most common indication for M3M extraction

Anaerobic microbes
* Streptococci , Actinomyces, Propionibacterium, a beta-lactamase producing Prevotella, Bacteroides, Fusobacterium, Capnocytophaga and Staphylococci most common

33
Q

signs and symptoms of periocoronitis

13

A

Pain – developing, throbbing

Swelling – Intra or extraoral
* Angle of mandible, submandibular, lateral to buccal space, or under tongue to submasseteric space (unable to open mouth/trismus), sublingual, parapharyngeal space (dysphagia (unable to swallow)

Bad taste

Pus discharge

Occlusal trauma to operculum

Ulceration of operculum

Evidence of cheek biting

Foetor oris

Limited mouth opening/ trismus

Dysphagia

Pyrexia

Malaise

Regional lymphadenopathy

34
Q

tx options for pericoronitis

4

A

Incision of localised pericoronal abscess if required

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

Irrigation with warm saline or chlorhexidine mouthwash (10-20ml syringe with blunt needle – under the operculum).
* Please note some health authorities may recommend that you do not use chlorhexidine due to cases of anaphylaxis. Follow your health authority and local guidelines

Extraction of upper third molar if traumatising the operculum

35
Q

pt instructions for pericoronitis care

A

Patient instructed on frequent warm saline or chlorhexidine mouthwashes – reduce chance of pericoronitis returning

Advice regarding analgesia (follow pack)

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

36
Q

antibiotics for pericoronitis?

A

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 (dysphagia, breathing difficulty or significant trismus)

37
Q

predisposing factors for pericoronitis

7

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

BDS4 CDS Oral Surgery (19 decks)

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