OS - third molars

Question 1

list the requirements for surgical removal of teeth

Answer 1

• when you cannot remove/ xLA a tooth conventionally
• gross caries
• complex root morphology
• retained roots below bone
• impacted teeth
• displaced teeth
• ectopic teeth
• pathology (cysts, external root resorption)

Question 2

why may you have to surgically remove a tooth with gross caries?

Answer 2

unable to use forceps
no application point for elevators

Question 3

why may you have to surgically remove retained roots that are below alveolar bone level?

Answer 3

no application point for elevators

Question 4

in general terms, why does impaction occur?

Answer 4

prevention of complete eruption into a normal functional position due to lack of space or development in an abnormal position.

Question 5

why may impaction predispose pathological changes?

Answer 5

while the tooth germ is forming there is a pathological change that affects the tooth - can involve soft tissues or hard and soft tissues.

Question 6

aetiology of ectopic teeth?

Answer 6

malpositioned due to congenital factors

Question 7

aetiology of displaced teeth?

Answer 7

malpositioned due to presence of pathology i.e., a cyst

Question 8

describe completely unerupted teeth?

Answer 8

entirely covered by soft tissue and also partially/ totally covered in alveolar bone

Question 9

describe ankylosed teeth?

Answer 9

fused with alveolar bone, rare with 8s, occurs after middle age

Question 10

what is the cause of impacted teeth?

Answer 10

due to lack of space in the arch as a consequence of evolutionary changes and lack of an abrasive diet

Question 11

list in order the commonest affected impacted teeth?

Answer 11

mandibular third molars
maxillary canines
mandibular premolars/canines
maxillary incisors
maxillary third molars

Question 12

at what age do mandibular third molars usually emerge?

Answer 12

18-24 years

Question 13

what is the prevalence of mandibular third molars to fail to develop?

Answer 13

1:4 adults

Question 14

what is the prevalence of impacted third mandibular molars?

Answer 14

72%

Question 15

what is is the decision for xLA mandibular third molars?

Answer 15

decision to remove based on balance of risk of observation against removal before overt disease develops

Question 16

what guidelines are followed for removal of third molars?

Answer 16

National Institute for Clinical Excellence (NICE) 2000

Question 17

list the indications for removal of mandibular third molars

Answer 17

pericoronitis
unrestorable caries
cellulitis/ osteomyelitis
periodontal disease
ortho reasons
prophylactic removal in medically compromised pts
obscure pain
disease of follicle
orthognathic surgery
transplant donor

Question 18

what happens to teeth in the line of a fracture?

Answer 18

non vital

Question 19

what are the relative contraindications for removal of third molars?

Answer 19

asymptomatic teeth
non-compliant patients
overt nerve involvement

Question 20

what is pericoronitis?

Answer 20

inflammation of the tissues around the crown of any partially erupted/ impacted tooth

Question 21

how many episodes of pericoronitis makes it an indication for xLA?

Answer 21

2 or more

Question 22

list the features of pericoronitis?

Answer 22

trismus, pain, dysphagia, malaise, bad taste
signs of inflammation of the pericoronal tissues, with pus under operculum
halitosis, food packing
can progress with systemic symptoms and spread to adjacent tissue spaces

Question 23

what is commonly performed in America to solve pericoronitis?

Answer 23

operculectomy

Question 24

why do we not routinely practise operculectomy’s?

Answer 24

operculum will grow back

Question 25

treatment options for a tooth in whose soft tissues have been traumatised from upper molar?

Answer 25

xLA upper 8 grind upper 8 cusps down

Question 26

treatment options for pericoronitis?

Answer 26

local measures - irrigation, OHI (small headed tooth brush/ water pick) - remove trauma i.e., xLA upper 8 or grind down cusps general measures - analgesics, antibiotics if systemically unwell/ immunocompromised - admission in severe airway threatening cases

Question 27

list the microbes associated with pericoronitis?

Answer 27

predominantly anaerobic strep, actinomyces, propionibacterium, a-beta-lactamase producing prevotella, bacteroides, fusobacterium, capnocytophaga and staph

Question 28

what anaerobes are related to the increased incidence of second and third molar perio pockets deepening over 2 years?

Answer 28

prevotella intermedia campylobacter

Question 29

when can antibiotics be prescribed for pericoronitis?

Answer 29

when surgical removal of the cause or drainage of the infection under LA is impossible e.g., trismus, pt compliance evidence of a systemic spreading infection needing urgent referral for hospitalisation

Question 30

what are conservative treatment choices for removal of mandibular third molars?

Answer 30

monitor with radiographs

Question 31

what treatment option is available for mandibular third molars if there is risk of damaging the inferior dental canal?

Answer 31

coronectomy

Question 32

what may happen to existing TMJ pain after xLA?

Answer 32

worsens

Question 33

what is the 7 at risk of with xLA of the 8 where there are perio pockets?

Answer 33

distal root exposure - sensitive

Question 34

what radiographs are generally required to assess mandibular wisdom teeth?

Answer 34

OPG PA sometimes - shows root apices and relation to IDC

Question 35

what do radiographs assess with mandibular third molars?

Answer 35

all the tooth and adjacent structures including bone, tooth morphology and number and shape of the roots, hypercemetosis depth of bone around tooth follilcular pattern external root resorption caries in distal of 7

Question 36

what classifications are made from radiograph assessment?

Answer 36

relation angulation to the adjacent teeth proximity to the IDNerve

Question 37

when radiographically classifying mandibular third molars, what is relation?

Answer 37

relation to the 7, crown, ACJ or roots

Question 38

when radiographically classifying mandibular third molars, what types of angulations can you get?

Answer 38

vertical mesioangular distoangular horizontal transverse aberrant

Question 39

what do Winter's assess?

Answer 39

how much bone will be removed

Question 40

what are the 3 winters lines?

Answer 40

occlusal plane line bone margins vertical line that joins

Question 41

what is the most common angle of impaction of 3rd molars?

Answer 41

mesial

Question 42

list 6 radiographic signs of a close relationship between the lower third molar and the IDC

Answer 42

1. diversion of IDC 2. darkening of root as it is crossed by the IDC 3. loss of lamina dura of IDC 4. narrowing of IDC 5. deflection of roots of lower third molar as they approach the IDC 6. juxta apical area

Question 43

what is a juxta apical area?

Answer 43

free floating apex on one side of the IDC

Question 44

what is indicated when the IDC passes through the roots of a tooth but both lines are interrupted?

Answer 44

superimposition

Question 45

what is indicated when there is loss of IDC lamina dura as it passes through the roots of a tooth?

Answer 45

close relationship - can cause bruising to canal which will give pt an altered sensation to the lip

Question 46

what is indicated when the IDC lamina dura is lost and there is a change in radiolucency of the roots?

Answer 46

suggests less mineralised tissue - canal is sititng in the groove of roots or perforates them

Question 47

what are the risks with a narrowed IDC?

Answer 47

indicates a close relationship to the roots - short term complication however, if roots are rotated on removal - long term complication

Question 48

where do the vast majority of IDC sit?

Answer 48

on the lingual aspect of the third molars (70%)

Question 49

what must you do with a pt if they IDC is interrupted when the third molar is removed and you can see the contents of the bundle left in the socket?

Answer 49

review and document sensation for 18 months if still numb after 18 months, unlikely to improve

Question 50

what is the prevalence of lower lip altered sensation in short and long term post op?

Answer 50

short term - 5% long term - less than 15%

Question 51

what is the prevalence of tongue altered sensation short term and long term post op?

Answer 51

short term - 10% long term - less than 1% taste can be affected too

Question 52

what is an alternative surgery performed if the risk is high to the IDN?

Answer 52

coronectomy - remove the crown and leave roots in place

Question 53

when performing a coronectomy, you realise the roots are mobile, what do you do?

Answer 53

remove them

Question 54

what are the risks following a coronectomy?

Answer 54

root removal unavoidable infection migration of roots

Question 55

what should happen to the socket after a coronectomy?

Answer 55

socket should fill with bone, roots become intraalveolar

Question 56

describe anaesthesia after LA

Answer 56

numbness

Question 57

describe paraesthesia after LA

Answer 57

tingling when LA wearing off

Question 58

describe hypoaesthesia after LA

Answer 58

reduced sensation

Question 59

describe disaesthesia after LA

Answer 59

pain

Question 60

what are the preoperative warnings you tell the pt prior to surgery of 3M?

Answer 60

pain swelling bruising possible hypoaesthesia of lip/tongue trismus diet advice 1 week

Question 61

what must pt be warned of prior to surgery of 3M

Answer 61

post op complications greater than 5% incidence

Question 62

what are the 5 points planned from a radiograph for surgical xLA of a mandibular 3rd molar?

Answer 62

path of eruption extrinsic/ intrinsic obstacles to removal required bone removal point of application flap design

Question 63

what are extrinsic obstacles to removal of mandibular third molars

Answer 63

adjacent teeth IDN

Question 64

what are intrinsic obstacles to removal of mandibular third molars?

Answer 64

converge, diverge, bulbous, fused, ankylosed roots

Question 65

describe a triangular flap

Answer 65

distal relieving incision up the ascending ramus, around crown of 3M, including papilla between 3M and 2M mesial relieving incision (3 sided)

Question 66

how does an envelope flap differ to a triangular flap?

Answer 66

no mesial relieving incision in envelop flap

Question 67

during a surgical removal of 3M what elevation technique and elevators are used?

Answer 67

atraumatic elevation using periosteal elevators - mitchells trimmer - warwick james elevator - molt no.9 periosteal elevator - Howarth's periosteal elevator

Question 68

during surgical removal of 3M, what is used to raise lingual flap?

Answer 68

Howarths/Mitchells/Molt *not for novice operators

Question 69

describe an envelope flap

Answer 69

distal relieving incision peri-coronal incision round 3M and 2M

Question 70

how are burs used for bone removal?

Answer 70

round bur creates narrow gutter mesiobuccaly fissure bur deepens gutter

Question 71

units of a surgical handpiece?

Answer 71

20000-40000 units per min

Question 72

how can the crown of a 3M be divided during surgical removal?

Answer 72

horizontally or axially *ALL horizontally impacted teeth must be sectioned

Question 73

what is important when planning flap design after surgical xLA 3M?

Answer 73

flap must rest over bone to avoid wound breakdown

Question 74

what is the most important suture?

Answer 74

one placed from the buccal tissue to the lingual tissue immediately distal to the second molar - encourages good periodontal health

Question 75

what material is used for suturing?

Answer 75

3/0 vicryl rapide - it is resorbable

Question 76

post op regime for surgical xLA?

Answer 76

analgesics soft diet topical ice pack HSMW day after suture removal at 1 week if not resorbed follow up for immunocompromised or difficult cases

Question 77

what analgesics are recommended post op?

Answer 77

paracetamol cocodamol 5 days NSAIDs

Question 78

when would you give a pt antibiotics?

Answer 78

immunocompromised pt returns with infection

Question 79

how would you tell a pt to use ice packs?

Answer 79

15 mins on 15 mins off day of tx

Question 80

when is post op bruising common?

Answer 80

elderly as tissue loses elasticity gravity can make bleeding track down neck

Question 81

list complications of surgery xLA 3M?

Answer 81

haemorrhage - primary/ secondary loose teeth/ damage to adjacent teeth/ restorations fractured mandible dry socket sensory deficit general xLA complications

Question 82

how are maxillary third molars commonly impacted?

Answer 82

MA V

Question 83

why are surgicals of maxillary third molars less complicated?

Answer 83

thin cortical bone

Question 84

how may access be difficult to maxillary third molars?

Answer 84

malar buttress buccal position

Question 85

when would you merit removal of upper 8's?

Answer 85

GA for removal of symptomatic lower 8s

Question 86

complications of a buccal placed maxillary third molar?

Answer 86

ulceration of buccal tissue painful mouth opening

Question 87

explain surgical removal of unerupted maxillary 3M?

Answer 87

raise buccal flap thin friable bone removed with couplands elevate back and buccal

Question 88

why do we avoid excessive upwards force with removal of maxillary 3Ms?

Answer 88

possible displacement into antrum

Question 89

how many sutures are used after removal of maxillary 3M?

Answer 89

1