Retention form in class II cavity for amalgam

 # Retention form in class II cavity for amalgam is achieved from:

A. Reduction of cusps

B. Convergence of proximal and occlusal walls occlusally

C. Flat gingival seat

Parallel proximal and occlusal walls

The correct answer is B. Convergence of proximal and occlusal walls occlusally.

The design of preparation primary retention form is directly related to the retention needs of the anticipated restorative material. Amalgam restoration of a Class I or II preparation is retained by developing external tooth walls that converge occlusally. In this way, when the amalgam is placed in the preparation and hardens, it cannot be dislodged. However, excessive occlusal convergence of the external walls will result in unsupported enamel rods at the cavosurface margin and must be avoided.

Ref: Sturdevant’s Art and Science of Operative Dentistry, 7th Edition, Page no 128

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Initiator/accelerator systems needed for a light activated composite

 # Which of the following initiator/accelerator systems is needed for a light activated composite?

A. Peroxide amine

B. Diketone amine

C. Organic acid –peroxide

D. Organic acid- metal ion

The correct answer is B. Diketone Amine.

The light-cure process is activated when a diketone photosensitizer such as camphorquinone (CQ) absorbs a quantum of blue light and forms an excited-state complex (exciplex) with an electron donor such as an amine (e.g., dimethylaminoethyl methacrylate [DMAEMA]).

Ref: Phillip’s science of Dental Materials, 12th Edition, Page no. 289

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Most difficult teeth to anesthetize with irreversible pulpitis

 # What are the most difficult teeth to anesthetize with irreversible pulpitis?

a. maxillary molars

b. mandibular molars

c. maxillary anterior teeth

d. maxillary premolars

The correct answer is B. Mandibular molars.

With irreversible pulpitis, the teeth most difficult to anesthetize are the mandibular molars, followed by (in order) the mandibular and maxillary premolars, maxillary molars, mandibular anterior teeth, and maxillary anterior teeth.

Ref: Endodontics Principles and Practice, Torabinejad, Fifth Edition, Page e26

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Which of the following is classified as a procedural accident?

 # Which of the following is classified as a procedural accident?

a. Extensive caries preventing adequate rubber dam isolation

b. Inability to obtain reliable pulp testing results

c. A separated instrument

d. Swelling after nonsurgical root canal treatment

The correct answer is C. A separated instrument.

Procedural accidents are one reason for referral and are a direct result of treatment rather than preoperative conditions, diagnostic testing, or postoperative symptoms. A separated instrument is one of the most difficult accidents to correct.

Ref: Endodontics Principles and Practice, Torabinejad, Fifth Edition, Page e17

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