third molars

Question 1

Indication for extraction of third molars (NICE guidelines)

Answer 1

1. cysts/pathology
2. recurrent pericoronitis (at least 2 episodes)
3. unrestorable caries
4. non-treatable pulpal and/or periapical pathology
5. abscess
6. osteomyelitis
7. internal/external resorption of the tooth or adjacent teeth
8. malignant tumour
9. trauma
10. infection
11. orthognathic surgery
12. infection: pericoronitis, osteomyelitis, osteonecrosis, osteoradionecrosis

Question 2

pericoronitis: definition

Answer 2

an infection of the soft tissue around the crown of a partially impacted tooth, usually caused by normal oral flora

Question 3

pericoronitis: causes

Answer 3

1. Compromised host defences (e.g. URTI, medication)
2. Minor trauma from opposing maxillary dentition (operculum)
3. Food trapping under the operculum
4. Bacterial infection - Strep and Anaerobes
5. Poor OH

Question 4

signs/symptoms of mild pericoronits

Answer 4

pain
halitosis
swelling
erythema
bad taste

Question 5

signs/symptoms of severe pericoronitis

Answer 5

pain
halitosis
swelling
erythema
bad taste

PLUS++

trismus
pyrexia (fever)
lymphadenopathy
malaise
dysphagia (difficulty swallowing)

Question 6

mild pericoronitis: management

Answer 6

local measures:
irrigate with warm saline
hydrogen peroxide
analgesia

*care with chlorhexidine- small risk of anaphylaxis

Question 7

severe pericoronitis: management

Answer 7

local measures:
irrigation with warm saline
hydrogen peroxide

analgesia
+
metronidazole 200mg TDS for 3/7
or
amoxicillin 500mg TDS for 3/7

Question 8

why is metronidazole a useful antibiotic for the treatment of pericoronitis?

Answer 8

pericoronitis is primarily caused by anaerobic bacteria.

The environment created by the partially erupted tooth and the overlying tissue (operculum) is oxygen-poor, which allows anaerobic bacteria to thrive.

Common Anaerobic Species:
These bacteria include species like Actinomyces, Prevotella, Veillonella, Fusobacterium, and Micromonas.

Question 9

NICE guidelines indications for XLA of wisdom teeth

Answer 9

Unrestorable caries
Non-treatable pulpal and/or periapical pathology
Cellulitis
Abscess
Osteomyelitis
Internal / External resorption of the tooth or adjacent teeth Fracture of tooth
Disease of the follicle inc cyst/tumour
Tooth / teeth impeding surgery
Reconstructuve jaw surgery
Tooth is involved in the field of tumour resection

Question 10

incidence of distal caries in M2M with adjacent M3M

what percentage of these were associated with mesioangular M3M?

Answer 10

19%

42%

Question 11

assessment of the patient prior to third molar surgery

Answer 11

1. patient factors:
   -age
   -SH
   -MH
   -drug history
   -BMI
   -ethnicity
   -capacity
2. surgical factors:
   -the third molar
   -periodontal status
   -surgical anatomy
   -systemic
   -mouth opening
   -adjacent structures
   -associated pathology
   -TMJ
   -the operator

Question 12

partially erupted mesioangular or horizontally positioned M3Ms: management

Answer 12

-Patients should be identified and noted of the risk of disease occuring.
-Management options must be provided along with their risks.
-If it is the patient’s decision to retain the M3M, then close clinical review is required with radiographic investigation, when indicated.
-The patient must also be informed that delaying the removal of the M3M until they are older, increases the risk of postoperative complications.

Question 13

what should the x-ray show prior to third molar surgery?

Answer 13

-Presence of caries
-Condition of existing restorations
-Alveolar bone levels
-Root morphology
-Morphology of pulp chamber
-Signs of periodontal pathology
-Position of unerupted teeth or retained roots
-Other pathology of the jaws
-Form and quality of edentulous ridge and underlying bone
-Boundaries of relevant anatomical features

Question 14

periapicals:

1. what they show
2. indications

Answer 14

1. intraoral, shows individual teeth and apical area.
2. -Detection of apical inflammation / infection
   -Assessment of the periodontal status
   -Post trauma
   - ?un-erupted teeth
   -Root morphology
   -During endodontics
   -Apical surgery
   -Apical pathology
   -Implants post op

Question 15

periapical: contraindications/limitations

Answer 15

Technique sensitive
Gag reflex
Peri-apical Edentulous alveolar ridge
Children Co-operation

Question 16

tomography: indications

Answer 16

-Bony lesion / unerupted tooth not visible on IO radiograph
-Grossly neglected mouth
-Periodontal bone support assessment +/- PA’s
-Assessment of third molars before surgery (not routine)
-Orthodontic assessment
-Trauma
-Antral disease
-Destructive disease of the articular surfgace of TMJ
-Vertical alveolar bone height and anatomy assessment for implants

Question 17

CBCT: advantages and disadvantages

Answer 17

Advantages:
Digital technique
Thin slices with variable thickness <1mm
Can be viewed in all planes Eliminates superimposition
High contrast resolution
CBCT reduction in dose Short scan time
High resolution
Interactive software

disadvantages:
Issues with artefacts

Question 18

third molar radiology: considerations

Answer 18

1. relationship to vital structures
2. configuration of the roots
3. condition of the surrounding bone

Question 19

IAN: what it contains and their positions

Answer 19

1. Inferior alveolar artery – likely posterior/postero-lateral to nerve
2. Inferior alveolar vein – no pattern, can be 2 veins, lateral to the bone
3. Inferior alveolar nerve – likely anterior to the vessel

Question 20

signs of close relationship between M3M and ID canal

Answer 20

1. dark and bifid apex of root
2. deflection of root
3. narrowing of root
4. narrowing of canal
5. darkening of roots
6. interruption of cortical white line of canal
7. deviation/diversion of canal

Question 21

third molar radiology: things to consider

Answer 21

1. relationship to vital structures
2. configuration of the roots
3. condition of the surrounding bone

Question 22

configuration of roots: what to look for

Answer 22

1. Number of roots
2. Curvature of roots
3. Degree of root divergence
4. Size & shape of roots
   -bulbous, conical, long, short, hooked
5. Other
   - root resorption, caries, ankylosis

Question 23

how to determine condition of surrounding bone

Answer 23

-radiographs unreliable, age is a good determinant

less than 18:
-less dense
-pliable
-expands
-bends
-easier to cut/expand

older than 35:
-much denser bone
-decreased flexibility
-decreased ability to expand
-more bone removal required
-higher risk of fracture

Question 24

predictors of difficulty of surgery

Answer 24

the most important= the amount of bone required to be removed

this is dictated by:
1. alveolar bone level
2. tooth position
3. application depth
4. point of elevation

Question 25

factors increasing the difficulty of extraction

Answer 25

Disto-angular positioning Long thin roots Divergent roots Narrow periodontal ligament space Close relation to the IAN Close relation to the mandibular second molar Dense bone.

Question 26

winter's lines -their use -what they indicate

Answer 26

-provides an assessment of the degree of difficulty of extraction of a M3M -As the red line increases by 1mm in length, the difficulty of extraction is three times more -If the line is less than 5mm in length then removal under local anaesthetic is appropriate. Anything above 5mm may require sedation or a general anaesthetic.

Question 27

what can cause an increased risk of complications for third molar surgery?

Answer 27

Underlying systemic disease Age Anatomical position of tooth and root morphology Local anatomical relationships Status of adjacent teeth Access Patient co-operation / compliance Bone density Ankylosis Infection Pathology

Question 28

what can happen if pericoronitis is left untreated?

Answer 28

abscess affecting the lingual, submandibular or buccal spaces

Question 29

factors to consider before XLA of third molars

Answer 29

1. patient factors: -age: risk of complications >35yo increases -social history: smoking -medical history: medications, e.g. bisphosphonates, anticoagulants, steroids, immunosuppressants -BMI 2. surgical factors: -morphology -proximity to adjacent structures -periodontal status -systemic involvement -mouth opening -associated pathology

Question 30

radiographic indications that nerves are proximal to the third molar and a CBCT is required: RCS guidelines

Answer 30

interruption of cortical white line of the canal diversion/deviation of canal darkening of roots

Question 31

when is a CBCT indicated?

Answer 31

when a conventional radiograph suggests a close relationship between a mandibular third molar and the ID canal when the decision to perform surgery has been made

Question 32

treatment options for the impacted third molar

Answer 32

1. conservative management/active clinical monitoring 2. operculectomy 3. complete extraction of third molar 4. coronectomy of third molar

Question 33

operculectomy

Answer 33

surgical procedure to remove the affected soft tissue covering a partially erupted third molar to enable effective oral hygiene

Question 34

coronectomy

Answer 34

the removal of a crown from a healthy tooth to prevent inferior alveolar nerve damage in high risk patients

Question 35

coronectomy: contraindications

Answer 35

caries with pulpal involvement teeth with infection or associated mobility apical disease associated pathology pre-orthognathic surgery immunocompromised patients pre-radiotherapy

Question 36

Risks of mandibular third molar surgery

Answer 36

temporary or permanent altered or loss of sensation to lower lip, skin of the chin, gums and lower teeth, tongue, some taste **on the side of the XLA + trismus

Question 37

if a patient presented with a swollen face and you suspect pericoronitis, what addition examinations/investigations would you perform?

Answer 37

check patient's temperature to determine whether the infection is systemic if temp is increased (normal 36.8 degrees), pyrexic perform vitality tests to check if there is a non vital molar. If there is a suggestion that there is a non-vital molar, a radiograph might be indicated

Question 38

dental/facial cellulitis

Answer 38

Untreated infection can spread to deep facial spaces resulting in airway compromise, sepsis, or infection of the orbit and brain. Pain, often with fever Facial swelling Patients with severe infection may exhibit: -Swelling involving orbit or deep spaces of the neck -Trismus and dysphagia -Unstable vital signs and other evidence of invasive infection

Question 39

what can happen if a patient is left untreated who presents with a swollen face and pericoronitis?

Answer 39

if the infection spreads posteriorly the patient's airway will be at risk can lead to dyspnoea (shortness of breath)

Question 40

ludwig's angina

Answer 40

bilateral infection involving the submandibular and sublingual spaces a type of cellulitis (inflammation of the tissues) that affects the floor of the mouth, submandibular, sublingual, and submental spaces. It's characterised by a rapid onset and spread of infection classic brawny broad-like induration of the neck is seen spread of infection rapidly involves the epiglottis or parapharyngeal spaces and causes airway obstruction

Question 41

winter's lines

Answer 41

3 imaginary lines drawn onto radiograph 1. white line runs along the occlusal plane 2. amber line runs along the upper bone surface through the interdental bone crests and along the bone surface behind the third molar 3. red line passes vertically at right angles to the white line to the application point for an elevator the angle of impaction is judged against the white line the amber line gives an indication of the amount of tooth tissue which will be visible when the periosteal flap is raised and the amount of bone removal required over the crown the red line gives an indication of the depth of bone removal required to gain a point of application for an elevator if the red line >5mm the extraction will need GA less than 5mm= LA