Intraoral Class II distalizers have the major disadvantage of:

 # Intraoral Class II distalizers have the major disadvantage of:

a) the need for patient compliance

b) a force vector passing coronally to the maxillary arch’s center of resistance

c) anterior anchorage loss

d) an inability to be used simultaneously with multibracket appliances

The correct answer is:

c) Anterior anchorage loss

Explanation:

Intraoral Class II distalizers, such as the Pendulum appliance, Distal Jet, or Forsus, rely on posterior force application to move the maxillary molars distally. However, a major drawback is anterior anchorage loss, meaning:

As the maxillary molars move distally, the anterior teeth tend to drift forward, leading to proclination of the incisors.

This can compromise the correction of a Class II malocclusion if not properly controlled with anchorage reinforcement.

Why not the other options?

(a) The need for patient compliance → Not true for most fixed distalizers (e.g., Pendulum, Distal Jet), but true for removable appliances like elastics or headgear.

(b) A force vector passing coronally to the maxillary arch’s center of resistance → This is a concern in some cases but not the primary disadvantage.

(d) An inability to be used simultaneously with multibracket appliances → Many distalizers can be used alongside braces (e.g., Forsus, Carriere Motion Appliance).

The Invisalign Palatal expander is directly printed from:

 # The Invisalign Palatal expander is directly printed from:

a) polyamide-12

b) TC-85

c) polymethyl methacrylate

d) thermoplastic polyurethane

The correct answer is A. Polyamide-12.

The Invisalign Palatal Expander (IPE) is 3D-printed directly from Polyamide-12 (PA-12), a biocompatible and durable nylon-based material. This material is widely used in medical applications due to its strength, flexibility, and resistance to wear. PA-12 allows for precise and customized expansion while maintaining patient comfort.

The Invisalign Palatal Expander (IPE) is designed to expand the dentition in increments of:

  # The Invisalign Palatal Expander (IPE) is designed to expand the dentition in increments of:

a) 0.1mm

b) 0.25mm

c) 0.5mm

d) 1mm

The correct answer is B. 0.25 mm.

The Invisalign Palatal Expander (IPE) uses a series of custom-designed, 3D-printed expansion trays to gradually widen the upper arch. It expands the dentition in controlled increments of 0.25mm per adjustment, ensuring a more comfortable and predictable expansion compared to traditional rapid palatal expanders (RPEs).

Following are "essential diagnostic criteria" according to Graber except:

 # Following are "essential diagnostic criteria" according to Graber except:

a) Case history

b) Facial photographs

c) Periapical x-rays

d) Lateral cephalograms

The correct answer is:

d) Lateral cephalograms

Graber's essential diagnostic criteria for orthodontic diagnosis typically include case history, facial photographs, and periapical x-rays. Lateral cephalograms, while useful for orthodontic analysis, are not considered part of the essential diagnostic criteria according to Graber.

In a trauma patient with intraoral bleeding, best way to secure airway is:

 # In a trauma patient with intraoral bleeding, best way to secure airway is:

A. Awake blind intubation

B. Awake fibreoptic intubation

C. Tracheostomy

D. Cricothyroidotomy

The correct answer is:

D. Cricothyroidotomy

Explanation:

In a trauma patient with intraoral bleeding, maintaining a secure airway is critical because blood in the oral cavity can obstruct visualization and aspiration can compromise the airway. Here's why cricothyroidotomy is the best option in this scenario:

1. Challenges with intubation in intraoral bleeding:

• Awake blind intubation (Option A) is highly unreliable due to the inability to visualize the airway and the presence of blood.
• Awake fibreoptic intubation (Option B) may not be feasible in this case because the blood obstructs the fibreoptic scope's view, making the procedure very difficult. 
• Although performing fiber-optic intubation under local anesthesia for achieving successful endotracheal intubation is one of the recommended methods in situations where airway management is difficult, the use of FOB (fiber-optic bronchoscope) is somewhat impractical in patients with maxillofacial trauma. Blood, vomitus, and secretions in the patient’s airway may preclude vision by fiber-optic instruments, and accomplish ing effective local anesthesia in the injured regions is difficult. Furthermore, the patient’s cooperation is essential for such an approach, and this cooperation is not easy to obtain in the trauma patient.

2. Tracheostomy (Option C):

   • While a tracheostomy can secure the airway, it is a more complex and time-consuming procedure than a cricothyroidotomy, making it less ideal in an emergency setting.

3. Cricothyroidotomy (Option D):

   • It is the fastest and most effective way to secure an airway in a patient with significant oral bleeding.
   • It bypasses the upper airway and oral cavity entirely, preventing further complications from blood aspiration.
   • Cricothyroidotomy is generally the procedure of choice in emergency situations where intubation is not feasible or has failed.

Summary:

In an emergency involving trauma with significant intraoral bleeding, cricothyroidotomy is the best and most practical approach for quickly securing the airway and ensuring the patient's survival.

Patients with organ transplants are most frequently infected with:

 # Patients with organ transplants are most frequently infected with:

A. Hepatitis A

B. Hepatitis B

C. CMV

D. EBV

The correct answer is:

C. CMV (Cytomegalovirus)

Explanation:

Cytomegalovirus (CMV) is the most common opportunistic infection in patients with organ transplants. This is because immunosuppressive therapy, which is necessary to prevent organ rejection, compromises the immune system, making the patient more vulnerable to infections.

CMV in transplant patients:

It can cause severe complications, including fever, gastrointestinal disease, pneumonitis, hepatitis, and graft rejection.

Reactivation of latent CMV or primary infection (from donor tissue or environmental exposure) is common.

Other options:

Hepatitis A: Rarely an issue in transplant patients since it does not become chronic and typically resolves without major complications.

Hepatitis B: Can cause complications in transplant patients, but it is less frequent than CMV. Pre-transplant screening and antiviral prophylaxis help manage the risk.

EBV (Epstein-Barr Virus): Can cause post-transplant lymphoproliferative disorder (PTLD), but it is less common than CMV.

In summary, CMV is the most frequent and clinically significant infection in transplant patients.

Which of the following hormones increase the sensitivity of heart to epinephrine?

 # Which of the following hormones increase the sensitivity of heart to epinephrine?

A. Parathyroid

B. Insulin

C. Thyroid

D. Glucagon

The correct answer is:

C. Thyroid

Explanation:

Thyroid hormones (primarily T3 and T4) increase the sensitivity of the heart to catecholamines, including epinephrine. This effect is due to:

• Increased β-adrenergic receptor density: Thyroid hormones upregulate the expression of β-adrenergic receptors in the heart, enhancing responsiveness to epinephrine and norepinephrine.
• Increased myocardial contractility and heart rate: By amplifying the effects of catecholamines, thyroid hormones contribute to increased cardiac output and sympathetic tone.

Other options:

• A. Parathyroid hormone (PTH): This hormone regulates calcium and phosphate metabolism, with no direct role in cardiac sensitivity to epinephrine.
• B. Insulin: While insulin affects glucose metabolism and has some cardiovascular effects, it does not directly increase heart sensitivity to epinephrine.
• D. Glucagon: Glucagon has some inotropic and chronotropic effects on the heart, but it does not enhance the heart's sensitivity to epinephrine.

Thyroid hormones play a key role in modulating the cardiovascular system, particularly through their interaction with catecholamines.