Endodontics
Course Review
Enoch Ng, DDS 2014
Effect of NSRCT on Dentin
-
Pulpless = 9% less moisture, does not lead to progressive changes in biomechanical dentin properties
-
Insignificant changes to punch shear strength, load to fracture, toughness
-
Slight changes to microhardness
-
Nonvital dentin NOT more brittle than vital dentin
o
Cumulative loss of tooth structure from caries, trauma, restoration, endo procedure more critical
o
Strength of dentin directly related to remaining dentin within root and coronal structure
-
Intact tooth able to deform under loads – physiologic loading causes deformation with complete elastic recovery
o
Loss of central core of tooth structure = elastic recovery doesn’t take place
-
Access prep
o
Reduces tooth stiffness 5%
o
MOD prep (loss of marginal ridges) – reduces tooth stiffness 60%
o
Loss of inner cuspal slopes that unite/support tooth increases potential fracture
-
Well-constructed coronal restoration as important as obturation
o
Full cuspal coverage, partial coverage
o
Amalgam, composite resin
o
Glass ionomer – not for occlusal restorations
Restorations
-
Posterior RCT tooth with cuspal coverage
o
5mm sound tooth structure from crest of bone to tooth margin
2mm ferrule (prevent tooth fracture), 3mm biologic width
-
Previous Crown with occlusal access
o
Amalgam, composite
-
Caries
o
Amalgam, composite
-
Composite Restorations (tooth with porcelain crown)
o
Etch porcelain with 10% HF for 1 min, rinse
o
Etch dentin with 37% phosphoric acid 15-20s, rinse
o
Dry, apply silane, prime and bond, light cure
o
Place flowable composite, place composite incrementally (2mm), light cure
o
Finish and polish, adjust occlusion
-
Amalgam coronal-radicular restoration
o
2mm amalgam placed into each canal and through pulp chamber
o
Requires crown coverage
o
After 4 years, 0% failure
Intracoronal Barriers
-
Gutta percha exposure can be completely contaminated within 3 days
-
Retreat if gutta percha exposed >30 days
-
Orifice barriers vital to long term success
o
Countersink orifice with System B
o
Clean orifices/pulpal floor with ^OH
o
Place temp/permanent orifice barrier over orifices and pulpal floor
o
1-2mm glass ionomer significantly reduces microleakage
