Malignant hyperthermia is caused by:

 # Malignant hyperthermia is caused by:

A. Suxamethonium

B. Thiopentone

C. Propofol

D. Cis-atracurium

The correct answer is A. Suxamethonium.

Malignant hyperthermia (MH) is a rare but life-threatening condition triggered in susceptible individuals by certain anesthetic agents. Suxamethonium (succinylcholine), a depolarizing neuromuscular blocker, and volatile anesthetic agents (e.g., halothane, sevoflurane) are common triggers. MH is caused by a genetic mutation in the ryanodine receptor (RYR1) or calcium channel, leading to uncontrolled calcium release in skeletal muscle, resulting in hypermetabolism, muscle rigidity, hyperthermia, and rhabdomyolysis.

The other options are not known to cause malignant hyperthermia:

• Thiopentone: A barbiturate used for induction of anesthesia, not a trigger for MH.
• Propofol: An intravenous anesthetic, considered safe in MH-susceptible individuals.
• Cis-atracurium: A non-depolarizing neuromuscular blocker, not associated with MH.

Sodium hypochlorite irrigation depends upon:

 # Sodium hypochlorite irrigation depends upon:

1. pH

2. Temperature

3. Volume

4. Concentration

A. 1 and 2

B. 2 and 3

C. 1 and 3

D. 2 and 4

The correct answer is: D. 2 and 4 (Temperature and Concentration)

Explanation:

The effectiveness of sodium hypochlorite (NaOCl) irrigation in endodontics depends significantly on:

1. Temperature: Increasing the temperature of sodium hypochlorite enhances its tissue-dissolving ability and antibacterial efficacy.

2. Concentration: Higher concentrations of sodium hypochlorite are more effective in tissue dissolution and microbial elimination. However, they can also increase the risk of cytotoxicity and irritation.

While pH and volume affect sodium hypochlorite's properties, they are not the primary factors affecting its irrigation efficacy.

Stain used to diagnose premalignant lesions of lip is:

 # Stain used to diagnose premalignant lesions of lip is:

A. Crystal violet

B. Giemsa

C. H and E

D. Toluidine blue

The correct answer is: D. Toluidine blue

Explanation:

Toluidine blue is a metachromatic dye that stains acidic tissue components and is commonly used to identify premalignant and malignant lesions. It has an affinity for DNA and RNA, highlighting areas of increased nuclear activity, such as dysplastic or malignant cells. This makes it particularly useful in diagnosing premalignant lesions of the lip and oral mucosa.

Cleft lip and palate is associated with all, EXCEPT:

 # Cleft lip and palate is associated with all, EXCEPT:

A. Van der Woude Syndrome

B. Gardner syndrome

C. Treacher Collin Syndrome

D. Pierre Robin Syndrome

The correct answer is:

B. Gardner syndrome

Explanation:

Van der Woude Syndrome:

This is a genetic condition commonly associated with cleft lip and/or palate. It is characterized by lip pits and other oral anomalies.

Gardner syndrome:

This syndrome is primarily associated with intestinal polyps, osteomas, and soft tissue tumors. It does not typically involve cleft lip or palate.

Treacher Collins Syndrome:

This genetic disorder affects craniofacial development and can be associated with cleft palate (though cleft lip is less common).

Pierre Robin Syndrome:

This condition is characterized by mandibular hypoplasia, glossoptosis, and cleft palate. Cleft palate is a hallmark feature of this syndrome.