Impacted third molars

Question 1

What is impaction?

Answer 1

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

Question 2

ectopic meaning

Answer 2

malpositioned if due to congenital factors

Question 3

displaced meaning

Answer 3

malpositioned due to presence of pathology

Question 4

explain a completely unerupted tooth

Answer 4

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

Question 5

explain an ankylosed tooth

Answer 5

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

Question 6

what causes impacted teeth?

Answer 6

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

Question 7

which teeth are most commonly impacted

Answer 7

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

Question 8

when to mandibular third molars emerge?

Answer 8

18-24 years old

Question 9

what ratio of mandibular third molars fail to develop?

Answer 9

1:4

Question 10

percentage of mandibular molars impacted

Answer 10

72%

Question 11

mandibular third molars indications for removal

Answer 11

pericoronitis, unrestorable caries, cellulitis/osteomyelitis, periodontal disease, orthodontic reasons

Question 12

What is pericoronitits?

Answer 12

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

Question 13

Features of pericoronitis

Answer 13

trismus, pain, dysphagia, signs of inflammation of pericoronal tissues, cheek biting, halitosis, food packing

Question 14

treatment for pericoronitits

Answer 14

local measures - irrigation, OH, remove trauma ie extract upper 8s or grind cusps
general measures - analgesics, antibiotics, admission in severe life threatening cases

Question 15

Is periocoronitis predominantly aerobic or anaerobic?

Answer 15

anaerobic

Question 16

Bacteria involved in pericoronitits

Answer 16

streptococci, actinomycetes, propionibacterium, beta-lactamase

Question 17

Bacteria involved in increased incidence of second and third molar periodontal pockets deepening?

Answer 17

prevotella intermedia and campylobacter rectus

Question 18

Treatment choices for mandibular third molars third molars

Answer 18

conservative, removal and coronectomy. Operculotomy is not recommended

Question 19

Factors influencing decision of treatment choices for mandibular third molars

Answer 19

systemic disease, age, anatomical position of tooth and root morphology, adjacent teeth and structures, limited access, patient compliance, quality of bone, presence of infection or pathology, TMJ problems

Question 20

What radiograph would you take to assess mandibular third molars

Answer 20

OPG (PA ca show root apices in relation to IDC)

Question 21

what are you looking for on the radiograph when assessing the mandibular third molars?

Answer 21

depth, relation, angulation to adjacent teeth, proximity to ID nerve

Question 22

To assess depth what colours (Winter lines) ?

Answer 22

white, amber and red

Question 23

What angulations to adjacent teeth can you have?

Answer 23

vertical, mesioangular, distoangular, horizontal, transverse, aberrant

Question 24

most common angle of impaction

Answer 24

mesial (40%)

Question 25

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

Answer 25

diversion of the IDC, darkening of root as it is crossed by the IDC, loss of lamina dura of IDC, narrowing of IDC, deflection of roots of lower third molar, juxta apical area

Question 26

Post operative alteration in sensation where in mouth?

Answer 26

lower lip and tongue

Question 27

What is the alternative surgery if there is a high risk to the IDN?

Answer 27

coronectomy

Question 28

What does a coronectomy involve?

Answer 28

remove the crown and leave the roots in place. if the roots are mobile at the time of the coronectomy remove them

Question 29

5 points planned from radiograph ?

Answer 29

what would be the path of eruption extrinsic/instrinsic obstacles of removal required bone removal point of application flap design

Question 30

What is a triangular flap

Answer 30

distal relieving incision up the ascending rams

Question 31

what is a envelope flap

Answer 31

no mesial relieving incision

Question 32

what are 2 intrinsic obstacles - root form/

Answer 32

convergent roots divergent roots

Question 33

Why after surgery would the flap rest on bone

Answer 33

to avoid wound breakdown

Question 34

what is the most important suture

Answer 34

the one placed from the buccal tissues to the lingual tissues

Question 35

Why is it better to place fewer sutures

Answer 35

better to secure primary closure and haemostats

Question 36

materials used for suturing flap

Answer 36

3/0 vicryl rapide

Question 37

Post op regime?

Answer 37

analgesics, HSMW, soft diet, topical ice packs, suture removal at one week if not restorable

Question 38

What are complications of impacted third molars xla?

Answer 38

heamorrhage (primary or secondary), loose teeth or damage to adjacent teeth, fracture mandible, dry socket, sensory deficit, complications generally associated with xla

Question 39

Maxillary third molar features

Answer 39

majority MA or V impacted, thin cortical bone ad short single root 74% cases

Question 40

Maxillary third molars extraction process if erupted?

Answer 40

elevation or forceps extraction

Question 41

Maxillary third molars unerupted process for xla?

Answer 41

raise buccal flap, thing friable bone removed, one suture to reposition flap