Functional cusp reduction

# The amount of functional cusp reduction required for metal-ceramic crown is -
a) 1.0 - 2.5 mm
b) 1.5 - 2.0 mm
c) 2.0 - 2.25 mm
d) 1.85 - 2.10 mm

The correct answer is B. 1.5 -2.0 mm. 

Metal ceramic restorations require a 1.5 - 2 mm reduction in the functional cusp and 1.0 - 1.5mm reduction in the non-functional cusp. 

Gutta percha removal

# Best method to remove gutta-percha in retreatment procedures:
A. Hand instrumentation
B. Automated instrumentation
C. Rotatory instruments
D. Ultrasonic instruments

The correct answer is A. Hand instrumentation

The coronal portion of gutta-percha obturations should always be drilled out, preferably by means of endodontic drills such as the Gates-Glidden or Peeso. Gutta-percha may be dissolved (solvent technique) or removed in its solid form (Solid gutta-percha techniques). Dissolving avoids the use of excessive force in the negotiating of gutta-percha-obturated canals.

Extrusion of solvent into the periapical tissues should be prevented.

Solvents of gutta-percha: Gutta-percha is soluble in chloroform, ethyl chloroform, carbon disulfide, carbon tetrachloride, benzene, xylene, eucalyptol oil, halothane, and rectified white turpentine.

Retreatment of solid objects other than gutta-percha, either a silver point or a fragment of an instrument or post, cannot be easily grasped and pulled out. A readily accessible solid object may be withdrawn from the canal by a variety of instruments, including Stieglitz or Perry pliers, a modified Castroviejos needle holder, or a Caulfield silver point extractor. Ultrasonic Vibration, bypassing with hand instruments and Intermittent irrigation, alternating sodium hypochlorite with hydrogen peroxide or RC-Prep, may float the object coronally through the effervescence they create.

Special grasping devices. The Masserann technique- Masserann and alternative extractors. The Masserann kit consists of an extractor into which the object to be retrieved is locked. An assortment of end-cutting trepan burs are used in anticlockwise rotation, to provide access for the extractor. 

Endodontic retreatment

# Endodontic retreatment:
A. Is as technically challenging as original treatment
B. Has a poorer prognosis than original treatment
C. Is performed only on endodontic failures
D. Has different objectives than primary treatment

The correct answer is B. has a poorer prognosis than the original treatment

Post and Core in Endodontics

# In restoring an endodontically treated tooth for post core, an absolute minimum of apical fill of gutta percha to be left over to prevent leakage is:
A. 1 mm
B. 2 mm
C. 3 mm
D. 4 mm

The correct answer is D. 4mm

Since there is greater leakage when only 2-3 mm of Gutta-percha is present, 4-5 mm should be retained apically to ensure an adequate seal. Although studies indicate that 4 mm produce an adequate seal, stopping precisely at 4 mm is difficult, and radiographic angulation errors could lead to retention of less than 4 mm. Therefore, 5 mm of gutta-percha should be retained apically. 

Concentration of EDTA used during BMP:

# Concentration of EDTA used during biomechanical preparation (BMP) is:
A. 20% at pH 7.4
B. 15% at pH 5.0
C. 15% at pH 7.3
D. 25% at pH 7.4

The correct answer is C. 15% at pH 7.3

EDTA has a property of chelate formation with calcium salts. Disodium salt of EDTA is used in endodontic therapy for dissolving pulp stones. 

Length of a Peeso reamer is:

# Length of a Peeso reamer is:
A. 28-32 mm
B. 30-35 mm
C. 35-40 mm
D. 40-45 mm

The correct answer is A. 28-32 mm

- Standard Peeso reamer is of 32 mm length.

- Short Peeso reamer is of 28 mm length.

Cardiac glycosides:

# Which of the following is called cardiac glycosides?
A. Digitalin
B. Belladonna
C. Reserpine
D. Colchicum

Cardiac glycosides are a class of organic compounds that increase the output force of the heart and increase its rate of contractions by acting on the cellular sodium-potassium ATPase pump. Their beneficial medical uses are as treatments for congestive heart failure and cardiac arrhythmias; however, their relative toxicity prevents them from being widely used.

Cardiac glycosides can be more specifically categorized based on the plant they are derived from, as in the following list. For example, cardenolides have been primarily derived from the foxglove plants Digitalis purpurea and Digitalis lanata, while bufadienolides have been derived from the venom of the cane toad Bufo marinus, from which they receive the “bufo” portion of their name.

Cardiac glycosides have long served as the main medical treatment to congestive heart failure and cardiac arrhythmia, due to their effects of increasing the force of muscle contraction while reducing heart rate. Heart failure is characterized by an inability to pump enough blood to support the body, possibly due to a decrease in the volume of the blood or its contractile force. Treatments for the condition thus focus on lowering blood pressure, so that the heart does not have to exert as much force to pump the blood, or directly increasing the heart's contractile force, so that the heart can overcome the higher blood pressure. Cardiac glycosides, such as the commonly used digoxin and digitoxin, deal with the latter, due to their positive inotropic activity. On the other hand, cardiac arrhythmia are changes in heart rate, whether faster (tachycardia) or slower (bradycardia). Medicinal treatments for this condition work primarily to counteract tachycardia or atrial fibrillation by slowing down heart rate, as done by cardiac glycosides.

Nevertheless, due to questions of toxicity and dosage, cardiac glycosides have been replaced with synthetic drugs such as ACE inhibitors and beta blockers and are no longer used as the primary medical treatment for such conditions. Depending on the severity of the condition, though, they may still be used in conjunction with other treatments.