Protection of posterior teeth undergoing endodontic therapy

Question 1

Why do they require protection?

Answer 1

Reduced tooth structure
Access cavity
Loss of marginal ridges
Axial forces can flex cusps
Non-axial forces are even more damaging

Question 2

Canine guidance

Answer 2

usually ideal as it protects the posterior

teeth

Question 3

Group function

Answer 3

More than one tooth involved

Damaging to posterior teeth esp if root treated

Question 4

Non-working side

Answer 4

Guidance in lateral excursions on opposite side to movement of mandible

Question 5

Premolars

Answer 5

Premolars are most at risk as they are more commonly
involved in group function compared to molars
Premolars are often also weaker due to comparatively more
tooth tissue loss

Question 6

Forces on posterior teeth may lead to

Answer 6

Cusp fracture

Question 7

Risk of fracture increases as

Answer 7

Tooth becomes more heavily restored

Question 8

Options for protecting posterior teeth with weakened structure

Answer 8

Interim measures

Definitive measures

Question 9

Interim measures of protection prior to endo

Answer 9

Occlusal adjustment to reduce loading
Cusp reduction and overlay restoration
Cemented orthodontic band
Interim crown (metal/composite/acrylic)

Question 10

Definitive measures of protection prior to endo

Answer 10

Cusp reduction and overlay restoration
Onlay/Overlay indirect restoration
Full crown

Question 11

Occlusal adjustments

Answer 11

Reduce occlusal loading
Use occlusal marking to highlight points in ICP
Highlight lateral excursive contacts
Remove lateral excursive contacts

Question 12

What can occur when changing occlusion

Answer 12

Transfer of guidance to other teeth
Introduction of interfering contacts
Accidental loss of ICP contacts
Test on study models first

Question 13

Cusp reduction and overlay placement

Answer 13

Reduce cusps by 2-3mm with a bur
Use composite/amalgam to build tooth up
Ensure ICP restored
Keep excursive contacts to a min

Question 14

Properties of onlay/overlay indirect restoration

Answer 14

Provides a strong, indirect
restorative option, whilst still
conserving tooth tissue compared
to a full coverage crown
Traditionally made from gold, but
can also be constructed from high strength porcelain or composite
Can be cemented with an adhesive
cement

Question 15

Full coverage crown properties

Answer 15

Full coverage and good seal but more tooth tissue lost

Access + coverage prep