Dentosphere : World of Dentistry

 # Which one of the following drug does not cause gingival hyperplasia? A. Cyclosporine B. Phenytoin C. Phenobarbital D. Nifedipine The correct answer is: C. Phenobarbital Explanation: Gingival hyperplasia is a common side effect of certain drugs due to their impact on fibroblast activity and collagen metabolism. Cyclosporine : An immunosuppressant commonly associated with gingival hyperplasia. Phenytoin : An antiepileptic drug that frequently causes gingival overgrowth. Nifedipine : A calcium channel blocker linked to gingival hyperplasia, especially in patients with poor oral hygiene. Phenobarbital : An antiepileptic and sedative-hypnotic drug that does not typically cause gingival hyperplasia.

 # Which lesion is easy to detect radiographically? A. An incipient lesion  B. One that crosses the dentinoenamel junction (DEJ)  C. One confined to enamel  D. One with enamel demineralization  The correct answer is: B. One that crosses the dentinoenamel junction (DEJ) Explanation: Lesions that cross the DEJ are easier to detect radiographically because: Density Difference : When the lesion progresses beyond the DEJ, the change in tissue density between enamel and dentin becomes more pronounced, making it visible on radiographs. Dentin Involvement : Dentin is less mineralized than enamel, so demineralization in this layer appears more distinctly on radiographs. Other options: A. An incipient lesion : These are confined to the outer enamel and are challenging to detect radiographically due to minimal density changes. C. One confined to enamel : These may be faint or undetectable on radiographs, especially if demineralization is minor. D. One with enamel demineral...

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

 # Which of the following is not a systemic disorder causing delayed eruption of permanent teeth? A. Segmental odontomaxillary dysplasia B. Celiac disease C. Cerebral palsy D. Ichthyosis The answer is A. Segmental odontomaxillary dysplasia. Explanation: Segmental odontomaxillary dysplasia: This is a localized developmental disorder, not a systemic disorder. It affects the maxilla segmentally, often leading to delayed eruption of teeth in that specific area. However, it is not classified as a systemic disorder. Celiac disease: This is a systemic condition that can cause nutritional deficiencies (e.g., calcium, vitamin D), leading to delayed dental development and eruption. Cerebral palsy: A systemic neurological disorder that can indirectly delay the eruption of permanent teeth due to associated developmental challenges. Ichthyosis: Though primarily a skin disorder, certain severe systemic forms might cause delayed eruption due to associated developmental issues.