Principles of endodontic access

Question 1

Burs to use?

Answer 1

Long fissure bur for initial outline

Once into the chamber - change to non-end cutting bur to avoid damaging floor

Endo Z bur to refine cavity

Question 2

What does the size of the pulp chamber depend on?

Answer 2

age of tooth
History of trauma
Pulp chamber at CEJ and in the centre of
Measure before on external surface of tooth
Check depth as you go

“Drop” into chamber

Question 3

After you find the pulp chamber, what do you do?

Answer 3

place rubber dam and refine cavity

Question 4

How to seal the?

Answer 4

caulk

Irrigate with NAOCL

Question 5

What to use to confirm canal entrance?

Answer 5

DG16 probe

Question 6

How to irrigate canal?

Answer 6

remove pulp remnants / dentine chips

Bleaches floor helps with orifice location

Question 7

What can go wrong?

Answer 7

wrong tooth

Not in long axis of tooth

Can’t locate canal - wrong place

False canal creation - files catch

Perforation

Question 8

Problem with too small cavity?

Answer 8

• Pulp debris not removed
• Increase pressure on files
• Unable to locate canals
• Poor vision

Question 9

Problem with too big cavity?

Answer 9

• Weakened tooth
• Susceptible to irretrievable fracture
  of tooth
• Files catch on ”step”/ledge

Question 10

Are pulp chambers in the centre of the tooth?

Answer 10

yes

Question 11

Relationship of the pulp chamber floor?

Answer 11

• Floor of the pulp chamber is always a darker colour than the surrounding dentine
  walls
• This colour difference creates a distinct junction where the walls and the floor of the
  pulp chamber meet
• The orifices of the root canals are always located at the junction of the walls and
  floor
• The orifices of the root canals are located at the angles in the floor wall junction
• The orifices lay at the terminus of developmental root fusion lines, if present
• The developmental root fusion lines are darker than the floor colour
• Reparative dentine or calcifications are lighter than the pulp chamber floor and
  often obscure it and the orifices

Question 12

Aims of endodontic tx?

Answer 12

• Eliminate microbial infection
• Chemo-mechanical prep & disinfection of the RCS
• All canals must be located
• Magnification

Question 13

Anatomy of the RCS?

Answer 13

• Starts at CEJ >apical foramen
• Straight canals = not common
• Most have curve, or S-shaped curve
• Apical foramen usually w/in 3mm of anatomical root end
• Lateral and accessory canals common
• RCS often end in a delta

Question 14

Types of apical constriction?

Answer 14

major and minor

Question 15

What is the minimum left at the apex?

Answer 15

0.5-1mm short of radiographing apex

Question 16

Roots canal shales in cross section?

Answer 16

• Round
• Ribbon
• Figure of 8
• Ovoid
• Kidney bean
• C-shaped

Question 17

Why reduce occlusal height in multirooted teeth?

Answer 17

increase visibility and protect against fracture

Consistent reference point

Question 18

Preparing access cavity in multirooted teeth?

Answer 18

• Long fissured diamond
• Endo –Z bur
• Irrigate & use spoon excavator to remove remaining debris
• Identify canals w DG16
• Check straight line access
• Refine access cavity – remove shelves/bulges

Question 19

What teeth have a fast break?

Answer 19

lower premolars

Question 20

What is the biggest canal in lowers?

Answer 20

distal

Question 21

What is the biggest canal in upper teeth?

Answer 21

palatal

Question 22

How to confirm straight line access in multirooted teeth?

Answer 22

DG16 / size 10 flexofile

Coronal 2/3 only

Question 23

Where is MB 2 in relation to MB
1 in the upper 6?

Answer 23

around 1mm mesiopalatal