Cores for Posterior Root Treated Teeth

Question 1

What is the problem for making cores for Posterior teeth already treated for RCT

Answer 1

• Posterior teeth have divergent often curved root canals
• Prep of these canals for a ridged cast or wrought post system would perforate the canal
• Posterior teeth are grossly weakened due to the access during RCT putting a thick rigid post system would weaken it further

Question 2

How do we get around the problems for making cores for posterior teeth already treated with an RCT

Answer 2

• Using a plastic restoration held with pins (may also lead to perforation of the root canal system)
• Use a plastic restoration within the canal system of posterior teeth, filled as a continuum as support (Nayyar core)
• Use metal castings, custom for each patient

Question 3

What is a nayyar core

Answer 3

This is a technique by which a core is built up using amalgam in a root canal treated molar.

Retention for the amalgam core is derived from the remaining pulp chamber and the prepared canals, by extending amalgam to these areas

Question 4

Why is it important to carve the amalgam to the full contour

Answer 4

• Allows you to check the occlusion

- When you prepare the tooth for a crown it is easy to construct a provisional restoration

Question 5

Why is it no suitable to leave the occlusal surface flat

Answer 5

The opposing tooth can over-erupt

Question 6

AY BAWS CAN I HABE DE NOTE PLZ

Answer 6

Make sure you use a matrix band system with wedges when making the nayyar core

Question 7

What are the drawbacks of using composite for a nayyar core

Answer 7

• Many composite core materials are flowable composite and so have an 8-9% shirnkage
• Composite shrinks and then swells in the oral environment, if impressions for a crown are taken it can be difficult to fir the crown

Question 8

Why are long posts sometime impractical for posterior teeth

Answer 8

• Thin or ribbon shaped canals on some roots and the root curvature

Question 9

Which canals tend to have thin/ribbon shaped canals

Answer 9

• Mesial canals on mandibular molars

- Buccal canals on maxillary molars

Question 10

What can we use for posts when long posts are impractical on posterior teeth

Answer 10

Locking posts (split-posts), which are complex and expensive but they have v effective retention

Question 11

What are the 3 steps and things you should check before making the access cavity for a nayyar core

Answer 11

• Establish absence of periapical pathology
• Assess quality of RCT
• Ensure adequate isolation using rubber dam

Question 12

What do you remove the IRM or GP from the pulpal floor using

Answer 12

A large rose head bur

Question 13

How much GP do you want to remove from the canal orifice for the nayyar core and what do you use to do it

Answer 13

• remove 3mm of GP from the canal orifice

- Use a goose neck bur

Question 14

After removing the GP what is next

Answer 14

Apply the matrix band with wedges to ensure good contact points