Rotated Maxillary Central Incisor

 # A child is brought to the clinic with complaint of irregular teeth. The maxillary central incisor is rotated in an otherwise normal occlusion. What should the next step be?

a) Check for supernumerary teeth

b) Resection of supracrestal fibers

c) Exert a couple on tooth

d) Fixed orthodontic appliances given  

The correct answer is a. Check for supernumerary teeth.

Unerupted mesiodens and the presence of thick labial frenum between the central incisors are common causes of midline diastema.

Before attempting to close midline diastema, radiographs should be taken to rule out supernumerary teeth as the cause of diastema.

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Agent approved as an immersion sterilant

 # Which of the following agents is approved as an immersion sterilant?

A. Ethyl alcohol

B. Glutaraldehyde

C. Iodophors

D. Sodium Hypochlorite

The correct answer is B. Glutaraldehyde.

Immersion sterilants are agents used to sterilize instruments by dipping them in their solution. 

Glutaraldehydes are used as a disinfectant and in fixing biological tissues for light and electron microscopy. This is the most widely used immersion sterilant. 

Glutaraldehyde, sold under the brandname Cidex and Glutaral among others, is a disinfectant, medication, preservative, and fixative. As a disinfectant, it is used to sterilize surgical instruments and other areas of hospitals.  As a medication, it is used to treat warts on the bottom of the feet. Glutaraldehyde is applied as a liquid.

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Endodontically treated teeth

 # Endodontically treated teeth:

A. Decay and breakdown rapidly

B. Require no special design or restoration

C. Are weak and can fracture due to occlusal forces

D. Are more stronger

The correct answer is C. Are weak and can fracture due to occlusal forces.

Routinely, teeth that have had endodontic treatment are weak and subject to fracture from occlusal forces. These teeth require restorations designed to provide protection from this injury. This particularly applies to posterior teeth, which are subjected to greater stress.

Ref: Sturdevant’s Art and Science of Operative Dentistry, 7th Edition, Page no e125

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Abfraction is caused by

 # A patient had a non carious lesion on the lower premolar and was diagnosed as abfraction. Abfraction is caused by:

A. Excess intake of aerated drinks

B. Excessive forces during brushing

C. Flexure of the tooth from occlusal trauma

D. Leaching of 30% hydrogen peroxide during walking bleach

The correct answer is C. Flexure of the tooth from occlusal trauma.

The loss of tooth structure in the cervical areas (abrasion) is commonly seen as a rounded notch in the gingival portion of the facial aspects of teeth. In contrast to cervical lesions that develop from abrasion processes, idiopathic erosion lesions (“abfractions”) are cervical, wedge-shaped defects (angular as opposed to rounded) similar to the defects customarily associated with abrasion but in which one of the possible causative factors may include excessive flexure of the tooth as a result of heavy, eccentric occlusal forces.  

Ref: Sturdevant’s Art and Science of Operative Dentistry, 7th Edition, Page no 106

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Over contouring of class II restoration:

 # Over contouring of class II restoration:

A. Leads to healing of periodontal tissues

B. Reduces the plaque in the subgingival area

C. Reduces food impaction by tight contacts

D. Leads to inflammation of the marginal gingiva

The correct answer is D. Leads to inflammation of the marginal gingiva.

Normal tooth contours must be recreated in the performance of operative dental procedures. Improper location and degree of facial or lingual convexities may result in iatrogenic injury in which the proper facial contour is disregarded in the design of the cervical area of a mandibular molar restoration. Overcontouring is the worst offender, usually resulting in increased plaque retention that leads to a chronic inflammatory state of the gingiva.

Ref: Sturdevant’s Art and Science of Operative Dentistry, 7th Edition, Page no 12

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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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