periradicular surgery key points

Question 1

reasons for post-tx disease (endo failure)

Answer 1

persistent infection
- bacteria and fungi retained in complex apical anatomical ramifications is the most common cause of PTD
secondary infection e.g. poor coronal seal or fracture
extraradicular biofilm (6%) - self-perpetuating
focal infection theory

Question 2

aim

Answer 2

to resolve periradicular disease
- to establish a root seal at the apex of a tooth or at the
point of perforation of a lateral perforation
- remove existing infection - curettage, enucleation of a cyst, removal of apical part of root which may have infected lateral canals

Question 3

objectives

Answer 3

to gain access to PR tissue
to gain access to the root end
to remove and clean the apical portion of the RC system
to seal the RC system
primary closure of the wound

Question 4

indications (over orthograde retx)

Answer 4

PTD in spite of excellent orthograde tx
extruded debris
iatrogenic damage
biopsy
extensive coronal restorations - but could have redone endo first

Question 5

what is not a good enough sole indication?

Answer 5

pain

Question 6

contraindications

Answer 6

poor coronal seal
 - need excellent coronal radiographic and clinical seal
unrestorable tooth
PDD and significant LOA
needs endo retx
v long post

Question 7

why is a v long post a contraindication?

Answer 7

once resect 3mm still need 3mm for retrograde Rx - length of post can render it unrestorable

Question 8

post perforation

Answer 8

sinus at mucogingival jct not further down
v deep localised pocket
no PA disease
post off-line with long axis of tooth

Question 9

CBCT

Answer 9

can be useful but refraction and beam hardening

• metal/amalgam
• some scanners can eliminate a lot of the scatter

Question 10

ideal flap design

Answer 10

split thickness papilla based incision

Question 11

process

Answer 11

raise flap - lots of saline irrigation
bone removal (osteotomy)
root end resection - 3mm at 90 degrees
debride crypt
root end prep - US
root filling
suture

Question 12

why 3mm resection?

Answer 12

removes 93% of apical ramifications and lateral canals, any iatrogenic mishaps, better access to debride the crypt
may be an extraradicular biofilm

Question 13

why perpendicular root end resection?

Answer 13

reduces exposed dentinal tubules

Question 14

gauze

Answer 14

helps with haemostasis but also catches spillage of the Rx material

Question 15

materials for root filling

Answer 15

MTA
(amalgam - historical)
zinc oxide/eugenol
bioceramic putty

Question 16

MTA

Answer 16

biocompatibility
moisture resistant
promotes cementogenesis - get cementum growing over top of it - hermetic seal. v good seal
£
hard to mix and time consuming to handle
long setting time

Question 17

zinc oxide/eugenol e.g. calzinol

Answer 17

cheap, easy to use
radiopaque
bacteriostatic
sensitive to moisture
may resorb
doesn't promote cementogenesis

Question 18

bioceramic putty

Answer 18

easier to handle - quicker surgical time - better healing and less post-op complications
more controllable
equivalent success rates to MTA

Question 19

using MTA

Answer 19

sand consistency “damp”
compact it to 3mm with plugger
72hrs to set
completely and tightly compacted and flush with root end, just in canal not on root

Question 20

reasons for failure

Answer 20

inadequate seal
 - extra/bifid root
 - too little apex removed "finning"
 - seal of incorrect shape
 - lateral perforation problem
 - displacement of seal
 - lateral canals
inadequate support
 - PD pockets
 - occlusal overload
 - excessive root resection
split roots
ST defect over apex post op