Number of point angles in class 3 cavity preparation is:

 # Number of point angles in class 3 cavity preparation is:

A. 4

B. 5

C. 3

D. 11

The correct answer is C. 3.

The three point angles are: 

i) Incisal Point Angle

ii) Axiofaciogingival point angle, and 

iii) Axiogingivolingual point angle.

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Removal of deep, pulp encroaching caries should be made using:

 # Removal of deep, pulp encroaching caries should be made using:

A. High rotational speeds

B. Low rotational speeds

C. Very high rotational speeds

D. All of the above

The correct answer is B. Low rotational speeds.

In deep carious lesion, wider dentinal tubules are present.(so sensitivity is more, which can be prevented by using coolants during cavity preparation, slow speed of instrument, biocompatible restorative material with suitable base).

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The average length of maxillary cuspid is:

 # The average length of maxillary cuspid is:

A. 26 mm

B. 33 mm

C. 21 mm

D. 18 mm

The correct answer is: A. 26 mm.

The average crown length of maxillary permanent canine is 10 mm and average root length is 17 mm. Hence, the average length of permanent maxillary canine is 27 mm.

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Best radiographic technique for demonstration of internal derangements of the TMJ

 # The best radiographic technique for demonstration of internal derangements of the TMJ is:

A. MRI

B. CT scan

C. Arthrography

D. Conventional radiographs

The correct answer is A. MRI. 

Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio waves to generate images of the organs in the body. MRI does not involve X-rays or the use of ionizing radiation, which distinguishes it from CT and PET scans. MRI is a medical application of nuclear magnetic resonance (NMR) which can also be used for imaging in other NMR applications, such as NMR spectroscopy.

MRI is widely used in hospitals and clinics for medical diagnosis, staging and follow-up of disease. Compared to CT, MRI provides better contrast in images of soft-tissues, e.g. in the brain or abdomen. However, it may be perceived as less comfortable by patients, due to the usually longer and louder measurements with the subject in a long, confining tube. Additionally, implants and other non-removable metal in the body can pose a risk and may exclude some patients from undergoing an MRI examination safely.

MRI: Distinguishes blood vessels and nerves from surrounding soft tissues.

MRI should not be used in patients with cardiac pacemakers, metallic restorations, and ortho-appliance

Internal derangement of TMJ can be best diagnosed by MRI.