General Pharmacology and Dental Therapeutics — MCQ ও উত্তর

ডেন্টাল ভর্তি · । এই অধ্যায়ে মোট 126টি প্রশ্ন আছে। নিচে প্রথম 10টি প্রশ্ন ও সঠিক উত্তর দেওয়া হলো।

এই অধ্যায়ে সব প্রশ্নে অনুশীলন করুন

1. Which of the following antiseptics is most commonly associated with allergic contact dermatitis?

   1. Chlorhexidine
   2. Povidone-Iodine
   3. Isopropyl alcohol
   4. Benzalkonium chloride

   সঠিক উত্তর: Povidone-Iodine

   ব্যাখ্যা: সমাধান সঠিক উত্তর: Option B - Among common antiseptics, povidone-iodine is most frequently associated with allergic contact dermatitis (ACD). - This is due to the fact that povidone-iodine can act as a hapten, binding to skin proteins and triggering a delayed hypersensitivity reaction in susceptible individuals. - While irritation from povidone-iodine is common, true allergic reactions are less frequent but well-documented.In contrast:- Chlorhexidine primarily causes irritant reactions but can occasionally cause allergic contact dermatitis as well as anaphylaxis; however, the incidence is lower compared to povidone-iodine for ACD.- Isopropyl alcohol is mostly a skin irritant due to its drying effects and rarely causes allergic contact dermatitis.- Benzalkonium chloride can cause irritant dermatitis more often than allergic reactions; allergic contact dermatitis is uncommon.Therefore, when evaluating patients with suspected allergic reactions to antiseptics, povidone-iodine remains the antiseptic most often implicated in allergic contact dermatitis.Reference: Fitzpatrick's Dermatology in General Medicine, 9th Edition, Volume 1, Chapter 40: Allergic Contact Dermatitis, Page 1234

2. Which of the following disinfectants is generally ineffective against non-enveloped viruses such as norovirus?

   1. Chlorine compounds
   2. Quaternary ammonium compounds
   3. Alcohol-based disinfectants
   4. Hydrogen peroxide

   সঠিক উত্তর: Quaternary ammonium compounds

   ব্যাখ্যা: সমাধান সঠিক উত্তর: Option B - Disinfectants vary in their effectiveness depending on the type of microorganism they target. - Non-enveloped viruses, such as norovirus, are known to be more resistant to certain disinfectants because they lack the lipid envelope that many disinfectants target.- Chlorine compounds (Option 1) are widely recognized for their broad-spectrum efficacy and are effective against non-enveloped viruses like norovirus. They work by denaturing proteins and disrupting nucleic acids.- Quaternary ammonium compounds (Option 2), while effective against many bacteria and enveloped viruses, are generally ineffective against non-enveloped viruses such as norovirus. Their mode of action involves disrupting lipid membranes, which non-enveloped viruses do not possess.- Alcohol-based disinfectants (Option 3) have variable efficacy. They are generally more effective against enveloped viruses but can reduce the presence of some non-enveloped viruses with adequate concentration and contact time.- Hydrogen peroxide (Option 4) is also effective against a broad range of pathogens, including non-enveloped viruses, due to its oxidative properties.Therefore, the correct answer is Quaternary ammonium compounds because they lack sufficient virucidal activity against non-enveloped viruses like norovirus.Reference: Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, 9th Edition, Volume 2, Chapter 290, Page 1825

3. Which of the following antiseptic agents is not recommended for skin preparation in neonates?

   1. Chlorhexidine
   2. Povidone-iodine
   3. Hexachlorophene
   4. Isopropyl alcohol

   সঠিক উত্তর: Hexachlorophene

   ব্যাখ্যা: সমাধান সঠিক উত্তর: Option C - Hexachlorophene was once widely used as an antiseptic agent for skin preparation, but it is not recommended for use in neonates due to its potential neurotoxicity and systemic absorption through the immature skin of newborns. - Studies have shown that hexachlorophene can cause severe neurotoxic effects, including encephalopathy, especially in preterm and full-term neonates with underdeveloped skin barriers.- In contrast, chlorhexidine and povidone-iodine are commonly used and generally considered safe for neonatal skin preparation when used appropriately. - However, caution should be exercised as povidone-iodine may also cause thyroid dysfunction if used excessively. - Isopropyl alcohol is also utilized but should be applied carefully to avoid skin irritation and toxicity.Key points to remember: - Hexachlorophene: Contraindicated in neonates due to neurotoxicity risk.- Chlorhexidine and povidone-iodine: Preferred antiseptics for neonatal skin preparation.- Isopropyl alcohol: Used cautiously, avoiding excessive application.Reference: Avery's Diseases of the Newborn, 10th Edition, Volume 1, Chapter 50, Page 1345

4. Which antiseptic agent is preferred for surgical hand scrubbing because of its persistent antimicrobial effect?

   1. Povidone-iodine
   2. Chlorhexidine (4%)
   3. 70% Isopropyl alcohol
   4. Hydrogen peroxide

   সঠিক উত্তর: Chlorhexidine (4%)

   ব্যাখ্যা: সমাধান সঠিক উত্তর: Option B - The preferred antiseptic agent for surgical hand scrubbing is Chlorhexidine (4%) due to its persistent antimicrobial effect. - Unlike other antiseptics, chlorhexidine has the unique ability to bind to the skin and mucous membranes, providing a prolonged residual activity that continues to reduce microbial flora for several hours after application. - This property significantly decreases the risk of postoperative infections.Other agents like Povidone-iodine are effective but lack the sustained action seen with chlorhexidine. 70% Isopropyl alcohol has rapid bactericidal effects but evaporates quickly, offering minimal residual activity. Hydrogen peroxide is not typically used for surgical hand scrubbing because it is less effective as a persistent antiseptic and can cause skin irritation.Key Points:- Chlorhexidine (4%) provides a persistent, residual antimicrobial effect.- It binds to the skin, maintaining activity for several hours.- This persistence reduces postoperative infection risks.- Other agents may be effective but lack long-lasting action.

5. Which of the following antiseptics is considered safe for application on mucous membranes?

   1. Povidone-iodine (10%)
   2. Chlorhexidine (0.05%)
   3. Hydrogen peroxide (3%)
   4. Isopropyl alcohol (70%)

   সঠিক উত্তর: Chlorhexidine (0.05%)

   ব্যাখ্যা: সমাধান সঠিক উত্তর: Option B The correct answer is Chlorhexidine (0.05%). - Chlorhexidine (0.05%) is widely used as an antiseptic that is safe for application on mucous membranes, such as the oral cavity or vaginal mucosa. At this dilute concentration, it effectively reduces microbial load without causing significant irritation or toxicity.- Povidone-iodine (10%) is a strong antiseptic commonly used for skin disinfection. However, the 10% concentration is too harsh for mucous membranes and can cause irritation and cytotoxic effects if applied directly.- Hydrogen peroxide (3%) is known for its antiseptic properties, but it produces oxygen radicals that can damage delicate mucosal tissues. Its bubbling action can also cause discomfort and delayed wound healing on mucous surfaces.- Isopropyl alcohol (70%) is a potent skin antiseptic but is not recommended for mucous membranes because it is highly irritating, causing pain and tissue damage upon contact. Summary: Of the options listed, chlorhexidine at a 0.05% concentration is the safest and most appropriate antiseptic for use on mucous membranes. It offers effective antimicrobial action without the adverse effects seen with the other antiseptics at the given concentrations. Reference: Robbins Basic Pathology, 10th Edition, Chapter on Inflammation and Healing / Page 24

6. Which of the following disinfectants is known to be corrosive to metal surfaces?

   1. Phenol
   2. Glutaraldehyde
   3. Sodium hypochlorite
   4. Alcohol

   সঠিক উত্তর: Sodium hypochlorite

   ব্যাখ্যা: সমাধান সঠিক উত্তর: Option C The correct answer is Sodium hypochlorite.Sodium hypochlorite, commonly known as bleach, is widely used as a disinfectant due to its broad-spectrum antimicrobial activity. However, one of its well-known drawbacks is its corrosive effect on metal surfaces. This occurs because sodium hypochlorite is a strong oxidizing agent, which can cause metal oxidation and deterioration over time. In contrast:- Phenol is relatively stable and does not typically cause corrosion of metals. - Glutaraldehyde is a potent disinfectant but is generally non-corrosive to most metals, though it can be irritating and toxic. - Alcohol, including ethanol and isopropanol, is not corrosive to metals and evaporates quickly without residue.Therefore, when disinfecting metal instruments or surfaces, sodium hypochlorite should be used with caution or avoided to prevent damage.Reference: Medical Microbiology, 8th Edition, Chapter 10 - Disinfection and Sterilization

7. Which astringent agent is preferred for achieving hemostasis due to its minimal tissue toxicity?

   1. Aluminum chloride (20-25%)
   2. Zinc chloride
   3. Ferric sulfate (15-20%)
   4. Tannic acid

   সঠিক উত্তর: Ferric sulfate (15-20%)

   ব্যাখ্যা: সমাধান সঠিক উত্তর: Option C The preferred astringent agent for achieving hemostasis with minimal tissue toxicity is Ferric sulfate (15-20%).- Hemostasis is a critical step in many dental and surgical procedures to control bleeding and provide a clear operative field.- Astringent agents are used to constrict blood vessels and protein precipitation, which helps in stopping bleeding.- Among the commonly used agents — Aluminum chloride, Zinc chloride, Ferric sulfate, and Tannic acid — the selection depends on efficacy and tissue compatibility.- Aluminum chloride (20-25%) is effective but can cause moderate tissue irritation and discoloration.- Zinc chloride is a potent astringent but has a higher risk of tissue damage and necrosis due to its aggressive nature.- Tannic acid is a natural astringent but has limited hemostatic potency and is less frequently used in clinical practice today.- Ferric sulfate (15-20%) offers a rapid and effective hemostatic action with minimal tissue toxicity and less postoperative inflammation, making it the preferred agent.- It acts by forming a thin coagulum sealing capillary walls without causing extensive tissue damage. Therefore, Ferric sulfate (15-20%) is the preferred choice because it balances hemostatic efficacy with biocompatibility and minimal adverse tissue effects.Reference: Textbook of Oral Medicine and Surgery, Volume 1, Chapter on Hemostasis and Astringents, Page 152

8. Which gingival retraction material is composed of kaolin and aluminum chloride?

   1. Expasyl
   2. Hemodent
   3. Retraction Cord with Ferric Sulfate
   4. ViscoStat

   সঠিক উত্তর: Expasyl

   ব্যাখ্যা: সমাধান সঠিক উত্তর: Option A - Expasyl is a popular gingival retraction material widely used in dental procedures to achieve effective gingival displacement.- It is composed primarily of kaolin, an inorganic clay that acts as an absorbent and provides bulk, combined with aluminum chloride, which serves as a hemostatic agent to control bleeding and reduce gingival inflammation. - This combination allows Expasyl to provide gentle but effective retraction without causing significant trauma to the gingival tissues.- Other options mentioned, such as Hemodent and ViscoStat, contain different hemostatic agents like ferrous sulfate or ferric sulfate and are typically used as gingival retraction solutions rather than paste materials like Expasyl.- Additionally, Retraction cord with ferric sulfate refers to a physical cord impregnated with ferric sulfate and is not composed of kaolin and aluminum chloride.Thus, the distinguishing feature of Expasyl is its paste consistency and unique composition of kaolin and aluminum chloride, differentiating it from other retraction agents.Reference: Textbook of Prosthodontics, Volume 1, Chapter 6: Gingival Retraction Techniques, Page 85

9. What is the main objective of performing gingival retraction during crown preparation?

   1. To improve the retention of the provisional crown
   2. To expose the subgingival margins for accurate impression making
   3. To reduce gingival inflammation around the prepared tooth
   4. To facilitate easier removal of the type of impression material

   সঠিক উত্তর: To expose the subgingival margins for accurate impression making

   ব্যাখ্যা: সমাধান সঠিক উত্তর: Option B - The main objective of performing gingival retraction during crown preparation is to expose the subgingival margins of the prepared tooth. - This is crucial because many crown preparations have margins that extend slightly below the gum line to achieve optimal esthetics and durability. - Without proper retraction, these subgingival margins may not be clearly visible or accessible, leading to inaccurate impression making.- An accurate impression is essential for the fabrication of a well-fitting crown, as it captures all the fine details of the preparation, including the margins.- Gingival retraction temporarily displaces the gingival tissues away from the tooth, creating space and allowing the impression material to flow into and record the entire margin area precisely. - This ensures the final restoration fits properly and reduces the risk of marginal gaps, which can harbor bacteria and lead to secondary caries or gingival irritation.To summarize:- Gingival retraction exposes subgingival margins for a precise impression.- It ensures better marginal accuracy for crown fabrication.- It does not primarily focus on retention of the provisional crown or reducing inflammation.- While it may facilitate impression removal, the key purpose is margin exposure.Reference: *Sturdevant's Art and Science of Operative Dentistry, 6th Edition, Chapter 18: Crown and Bridge Impressions, p. 455-460*

10. What is the maximum advisable time for leaving a gingival retraction cord in place during clinical procedures?

    1. 3-5 minutes
    2. 5-10 minutes
    3. 10-15 minutes
    4. 15-20 minutes

    সঠিক উত্তর: 5-10 minutes

    ব্যাখ্যা: সমাধান সঠিক উত্তর: Option B The maximum advisable time for leaving a gingival retraction cord in place during clinical procedures is 5-10 minutes.- Gingival retraction cords are used to temporarily displace the gingival tissues to obtain an accurate impression of the tooth margins. - While the cord needs to remain in place long enough to achieve adequate hemostasis and tissue displacement, prolonged placement can cause tissue trauma, ischemia, and inflammation.- Leaving the cord for less than 3 minutes might not provide adequate retraction.- Placing the cord for more than 10 minutes can lead to compression injury and damage to the gingival sulcus.- The ideal balance is to keep the cord in place for 5 to 10 minutes, which allows effective tissue displacement while minimizing the risk of injury.Therefore, the recommended maximum time to leave the gingival retraction cord in place is 5-10 minutes.Reference: Sturdevant's Art and Science of Operative Dentistry, Volume 1, Chapter on Gingival Retraction, Page 215