Coronectomy

Question 1

There is an associated risk of “dry socket” associated with coronectomies. True or false

Answer 1

True

Question 2

A loss of lamina dura of the canal is linked to …

Answer 2

contact of M3M with the canal

Question 3

What is the additional dose is associated with CBCT ?

Answer 3

60-120 uSv

Question 4

In cases where CBCT has shown no significant association with the IAN canal, it is beneficial to proceed with the M3M removal. Why is this?

Answer 4

• removes additional risk of future infection and resultant need for additional surgery of root removal

Question 5

What must you include when consenting patients for coronectomies?

Answer 5

• “it is intended for coronectomy to be undertaken, however, if the roots are mobilised during surgery then they will require removal with heightened risk of nerve injury”
• risk of infection which will necessitate removal of roots

Question 6

What risks are associated with retained roots following coronectomies that require removal?

Answer 6

although some of the roots erupt away from the IAN canal, the nerve may perforate the root and thus it drags the nerve superiorly as it erupts

Question 7

What LA is appropriate to deliver for M3M coronectomy?

Answer 7

Long buccal infiltration and anterior buccal infiltration using 4 ml of 4% articaine

Inferior dental block using 2% lidocaine may be used if necessary

Question 8

What flap is used to expose the M3M ?

Answer 8

buccal triangular mucoperiosteal flap

Question 9

What surgical technique can be used to prevent mobilisation of the root? What risk is associated with this technique?

Answer 9

extending sectioning of the crown from the roots

associated with increased risk to the lingual nerve

Question 10

What are the additional indications for elective coronectomy provided by the CBCT?

Answer 10

• loss of lingual cortex and buccally placed mandibular canal with M3M root sandwiched them

reduced lingual cortex-M3M root- buccal IAN canal

Question 11

Where is the gutter placed ?

Answer 11

on the bone adjacent and buccal to the tooth (NOT distal!)

Question 12

What is used to create the gutter ?

Answer 12

fissure bur

Question 13

What is the aim of the creation of a gutter?

Answer 13

expose the EDJ so that we can cut into the pulp

Question 14

Briefly describe how the fissure bur is used to drill directly into the pulp

Answer 14

• lateral cut is used to create a horizontal groove in the tooth, just below the EDJ
• depth of the cut should be into the pulp
• depth of the cut should be no longer than the length of the fissure bur avoid lingual perforation of the lingual cortical plate

Question 15

Following the horizontal groove creation, how is the crown seperated from the root ?

Answer 15

small elevator instrument such as coupland No.1 or straight warwick james is used to fracture off the crown from the roots

Question 16

Whilst fracturing off the crown from the roots, what must you take care not to do?

Answer 16

• must take care not to apply too much torque to the tooth as it may increase the risk of mobilisation of the root

Question 17

How would you manage a coronectomy for a mesioangular or horizontally impacted tooth?

Answer 17

• further sectioning to avoid damage to lower 2nd molar tooth

Question 18

What is used to remove any enamel spurs remaining on the root?

Answer 18

rose head bur

Question 19

What is an acceptable guidance for the amount of root that should be left behind?

Answer 19

• should be a few millimetres below the crestal bone level

Question 20

Ideally, where should alveolar bone be present following coronectomy?

Answer 20

should be above the root edges but this is not always possible (e.g. missing lingual plate)

Question 21

What type of suture is appropriate for closure following coronectomy ?

Answer 21

• resorbable
• single 4-0 vicryl

Question 22

How would you treat “dry socket” symptoms associated with a coronectomy?

Answer 22

• irrigation using chlorhexidine solution
• placement of resorbable dressing alvogyl