Third Molars 1

Question 1

3rd molars extracted where

Answer 1

referred to speciliast/hospital

rare to extract in practice

Question 2

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

true or false?

Answer 2

true

Question 3

eruption period for third molars

Answer 3

18-24y

Question 4

crown calcification of third molars

Answer 4

begins 7-10y and completed by 18y

7-9 for upper
8-10 for lower

Question 5

root calcification for third molars

Answer 5

18-25y

Question 6

how many adults have at least one third molar missing?

Answer 6

1 in 4 adults

Question 7

agenesis

Answer 7

failure of an organ to development

e.g. third molar

Question 8

common site for missing third molar development

Answer 8

maxilla

more in females

Question 9

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

Answer 9

14

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

Question 10

impacted means

Answer 10

tooth eruption is blocked

descriptive term
not indicative of surgery

Question 11

most common reason why third molars fail to erupt

Answer 11

impacted

Question 12

what can mandibular third molars be impacted against

Answer 12

adjacent tooth
alveolar bone
surrounding mucosal soft tissue

or combination of these factors

Question 13

options for eruption for impacted M3Ms

Answer 13

unerupted
partially erupted
fully erupted

Question 14

partially erupted

Answer 14

when some of the tooth has erupted into the oral cavity

Question 15

unerupted

Answer 15

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

Question 16

incidence of impacted lower third molars

Answer 16

36-59%

Question 17

consequences of impacted lower third molars

3

Answer 17

caries
pericoronitis
cyst formation

Question 18

cyst formation from lower third molars

Answer 18

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

Question 19

nerves at risk during M3M surgery

4

Answer 19

**inferior alveolar nerve
lingual nerve **

nerve to mylohyoid
long buccal nerve

Question 20

inferior alveolar nerve

what is it

Answer 20

peripheral sensory nerve from mandibular branch of trigeminal nerve

Question 21

inferior alveolar nerve

supplies

Answer 21

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

Question 22

inferior alveolar nerve

position

Answer 22

varies greatly from person to person

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

Question 23

lingual nerve

branch of

Answer 23

mandibular division of trigeminal nerve

Question 24

lingual nerve

supplies

Answer 24

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

Question 25

lingual nerve | position

Answer 25

* 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

Question 26

Guidelines role

Answer 26

help make clinical decisions based on evidence

Question 27

old Guidelines for third molar surgery

Answer 27

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)

Question 28

current used guideline for third molar surgery

Answer 28

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

Question 29

indications for extractions of third molars | 8

Answer 29

* 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*

Question 30

therapeutic indications for extractions of third molars | 4

Answer 30

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

Question 31

pericoronitis

Answer 31

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

Question 32

pericoronitis | features

Answer 32

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

Question 33

signs and symptoms of periocoronitis | 13

Answer 33

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

Question 34

tx options for pericoronitis | 4

Answer 34

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

Question 35

pt instructions for pericoronitis care

Answer 35

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)

Question 36

antibiotics for pericoronitis?

Answer 36

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)

Question 37

predisposing factors for pericoronitis | 7

Answer 37

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