What is the most superior point of the external auditory canal?

 # What is the most superior point of the external auditory canal?

A. Sella

B. Porion

C. Basion

D. Orbitale

The correct answer is B. Porion.

The porion is the most superior point of the external auditory canal. The sella is the center of the hypophyseal fossa. The basion is the most anterior point of the foramen magnum. The orbitale is the most inferior point of the infraorbital rim. 

Which factor requires careful consideration, when taking measurements from an image?

 # Which factor requires careful consideration, when taking measurements from an image? 

A. Definition 

B. Magnification 

C. Reconstruction 

D. Superimposition

The correct answer is B. Magnification.

The magnification factor of any image must be carefully considered when taking measurements. Image definition is significant to the overall diagnosis; however, the magnification factor is of special concern when calculating bone dimensions.  Image reconstruction is largely a function of multiplanar reformatting (MPR).  Superimposition is a factor for some images (panoramic radiographs and conventional tomograms); however, the magnification factor must be carefully considered when calculating bone dimensions. 

The common organism implicated in dry socket is:

 # The common organism implicated in dry socket is:

A. Streptococcus

B. Staphylococcus

C. Treponema denticola

D. Pneumococcus

The correct answer is C. Treponema denticola.

A number of bacteria are known to possess fibrinolytic activity. It has been recently postulated

that Treponema denticola may have an etiological role in the genesis of dry socket.

Irregular opaque areas are found on radiographs of lower anterior teeth, the teeth are vital. The cause may be:

 # Irregular opaque areas are found on radiographs of lower anterior teeth, the teeth are vital. The cause may be: 

A. Subgingival calculus 

B. Cementoma

C. Condensing osteitis 

D Chronic apical periodontitis 

The correct answer is A. Subgingival calculus.

Calculus may be seen as small angular radiopaque deposits projecting between interproximal surfaces of the teeth or as radiopaque bands across the roots representing circumferential accumulation as illustrated in the figure.

Ref: White, S.C. and Pharoah, M.J., 2014. Oral radiology-E-Book: Principles and interpretation. Elsevier Health Sciences.