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