Contraindicated beneath composite resins as liner or base

# Which of the following is contraindicated beneath composite resins as liner/ base?
A. Calcium hydroxide
B. Zinc oxide-eugenol
C. Glass ionomer
D. None of the above

The correct answer is B. Zinc oxide -eugenol.

The advantages of ZOE cement are that it gives excellent seal, has a sedative effect on prepared sensitive teeth, cost-effectiveness, and ease of removal of cemented temporary restorations. However, these materials have the disadvantage that eugenol hinders the polymerization of resin cements that are used to fix final restorations.

Tooth preparation usually exposes dentin, and hence, luting agents should possess property of being able to bond with the dentin. Eugenol used in cements for fixation of temporary restoration can penetrate into dentin and might affect adhesion of resin cements that are used for fixation of permanent restorations at a later stage. Hence, few authors suggested to use noneugenol cements for fixing interim restorations.

Ref: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5558255/

Most commonly fractured cusp is:

# Most commonly fractured cusp is:
A. Buccal cusps of maxillary molars
B. Buccal cusps of mandibular molars
C. Lingual cusps of maxillary molars
D. Lingual cusps of mandibular molars

The correct answer is D. Lingual cusps of mandibular molars.

Ref: Fennis, Willem & Kuijs, Ruud & Kreulen, Cees & Roeters, Joost & Creugers, Nico & Burgersdijk, Rob. (2002). A Survey of Cusp Fractures in a Population of General Dental Practices. The International journal of prosthodontics. 15. 559-63. 

File breakage in Endodontics

# Which of the following describes the BEST management strategy for a separated instrument AFTER cleaning and shaping has occurred?
A. Do not attempt to remove and proceed to obturation
B. Place calcium hydroxide
C. Attempt to bypass the instrument

The correct answer is A. Do not attempt to remove and proceed to obturation.

If an instrument separates at the filling/obturation stage, the instrument does NOT require removal because the etiology of the problem has already been resolved
through cleaning and shaping of the canals.

The prognosis for the tooth will be
considered more favorable if the infected
dentin has already been debrided from the
canal.

The prognosis for the tooth will also be
considered more favorably the more apical
the instrument separation occurred.

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Causes of Pulpal Necrosis

# Which of the following types of trauma is LEAST likely to result in pulpal necrosis?
A. Lateral luxation
B. Avulsion
C. Subluxation
D. Concussion
E. Extrusion 

The correct answer is D. Concussion. 

Concussion - An injury to the tooth supporting structures without increased

mobility or displacement of the tooth, but

can present with pain to percussion.

Pulpal necrosis can occur following a

serious tooth trauma, especially if the the

apical blood vessels are severed.

Subluxation- An injury to the tooth supporting structures resulting in increased

mobility, but without displacement of the

tooth. Bleeding from the gingival sulcus confirms the diagnosis.

Extrusion- The partial displacement of the

tooth out of its socket.

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