DiGeorge syndrome is due to:

 # DiGeorge syndrome is due to:

A. Congenital thymic aplasia

B. Deficiency of complement factors

C. Inborn error of metabolism

D. Chromosomal anomaly

The correct answer is D. Chromosomal anomaly.

The correct answer is:

D. Chromosomal anomaly

Explanation: DiGeorge syndrome is caused by a chromosomal anomaly, specifically a 22q11.2 deletion. 

This deletion leads to developmental defects in the pharyngeal pouches, resulting in: Congenital thymic aplasia or hypoplasia (leading to T-cell deficiency).

Parathyroid hypoplasia (causing hypocalcemia).

Cardiac defects (e.g., Tetralogy of Fallot, interrupted aortic arch).

Facial dysmorphisms.

Other options explained:

A. Congenital thymic aplasia: While thymic aplasia is a feature of DiGeorge syndrome, it is secondary to the chromosomal deletion.

B. Deficiency of complement factors: Seen in complement pathway defects, not in DiGeorge syndrome.

C. Inborn error of metabolism: DiGeorge syndrome is not related to metabolic enzyme deficiencies.

Chronic use of nasal decongestants, presented with abrupt onset of fever with chills and rigor, diplopia on lateral gaze

 # A 19 year old young girl with previous history of repeated pain over medial canthus and chronic use of nasal decongestants, presented with abrupt onset of fever with chills and rigor, diplopia on lateral gaze, moderate proptosis and chemosis. On examination, the optic disc is congested. Most likely diagnosis is:

A. Cavernous sinus thrombosis

B. Orbital cellulitis

C. Acute ethmoid sinusitis

D. Orbital apex syndrome

The correct answer is:

A. Cavernous sinus thrombosis

Explanation:
The clinical presentation described—abrupt onset of fever with chills, diplopia, proptosis, chemosis, and optic disc congestion—is characteristic of cavernous sinus thrombosis (CST). This condition is often secondary to infections in the medial canthus (commonly from facial infections or sinusitis), which can spread to the cavernous sinus via valveless facial veins.

Key Differentiation:

• B. Orbital cellulitis: Also presents with proptosis and chemosis but typically lacks systemic signs like severe fever with chills and is not associated with optic disc congestion or diplopia on lateral gaze.
• C. Acute ethmoid sinusitis: May cause pain over the medial canthus and fever but does not typically lead to proptosis, chemosis, or optic nerve involvement.
• D. Orbital apex syndrome: Involves cranial nerve deficits (II, III, IV, V, and VI) and visual loss, but the history of prior medial canthus pain and sinusitis with systemic signs strongly points to CST.

Cavernous sinus thrombosis is a medical emergency requiring immediate intervention with antibiotics and sometimes anticoagulation.

A 48 years old male reported to you with fractured central incisor with fracture line extending 4 mm gingival below CEJ with thin bone CEJ with thin bone buccally and thick apicopalatally, treatment of choice is:

 # A 48 years old male reported to you with fractured central incisor with fracture line extending 4 mm gingival below CEJ with thin bone CEJ with thin bone buccally and thick apicopalatally, treatment of choice is: 

A. Socket shield technique

B. Post and core

C. Extraction and implant

D. Socket preservation

The correct answer is:

Socket shield technique

Explanation: The socket shield technique is the preferred treatment in this scenario because it preserves the  buccal bone by retaining a thin section of the root (the "shield") after extraction. This technique is ideal for  cases where the buccal bone is thin, as it minimizes bone resorption and supports the soft tissue contour, especially in the aesthetic zone.

Other options explained:

B. Post and core: Suitable for coronal fractures but not when the fracture extends significantly below the CEJ.

C. Extraction and implant: A viable option but may lead to buccal bone loss in cases with thin buccal bone.

D. Socket preservation: Preserves the socket after extraction but does not directly address aesthetic or functional concerns in this case.

A patient has hypoplasia, microdontia, hypodontia, multiple unerupted teeth, numbness in oral cavity, peripheral paresthesia. This is most likely due to:

 # A patient has hypoplasia, microdontia, hypodontia, multiple unerupted teeth, numbness in oral cavity, peripheral paresthesia. This is most likely due to:

A. Hyperparathyroidism

B. Hypoparathyroidism

C. Hyperthyroidism

D. Hypothyroidism

The correct answer is:

B. Hypoparathyroidism

Explanation:
Hypoparathyroidism can cause a range of dental and neurological symptoms, including:

• Dental manifestations: Hypoplasia, microdontia, hypodontia, delayed eruption, and multiple unerupted teeth are associated with impaired calcium metabolism.
• Neurological symptoms: Numbness in the oral cavity and peripheral paresthesia occur due to hypocalcemia, which leads to increased neuromuscular excitability.

Other options explained:

• A. Hyperparathyroidism: May cause brown tumors, loss of lamina dura, and tooth mobility due to increased bone resorption, but not hypoplasia or unerupted teeth.
• C. Hyperthyroidism: Can lead to accelerated dental development but does not cause hypoplasia or hypodontia.
• D. Hypothyroidism: May cause delayed eruption and macroglossia but does not typically result in hypoplasia or paresthesia. 

The most well recognized technique for orthodontic bonding to porcelain surfaces is:

 # The most well recognized technique for orthodontic bonding to porcelain surfaces is:

A. Traditional acid-etch technique with phosphoric acid.

B. Chemical retention using 4-META coupling agent.

C. Chemical and micro-mechanical retention using hydrofluoric acid and a silane coupling agent.

D. Chemical retention using hydrofluoric acid only.

The correct answer is C. Chemical and micro-mechanical retention using hydrofluoric acid and a silane coupling agent

Explanation:
The most effective and well-recognized technique for bonding to porcelain involves etching the porcelain surface with hydrofluoric acid to create micro-mechanical retention, followed by the application of a silane coupling agent to enhance chemical adhesion. This combination ensures a strong bond between the orthodontic bracket and the porcelain surface.

• A: Phosphoric acid etching is effective for enamel but not adequate for porcelain bonding.
• B: 4-META is less commonly used for porcelain.
• D: Hydrofluoric acid alone provides micro-mechanical retention but lacks the chemical bond achieved with silane.

How many hours after appliance placement does orthodontic pain peak?

 # How many hours after appliance placement does orthodontic pain peak?

A. 10 minutes.

B. 1 hour.

C. 24 hours.

D. 48 hours.

The correct answer is C. 24 hours.

It is generally considered that orthodontic pain starts at around 2 hours after appliance placement, with some studies reporting that this is the case for between 91% and 97% of orthodontic patients. It then usually peaks at 24 hours before gradually subsiding over the next 5 to 7 days. Interestingly, it would seem that up to 25% of orthodontic patients report experiencing pain for longer than 7 days.

In pain pathways the smaller primary unmyelinated fibres are called:

 # In pain pathways the smaller primary unmyelinated fibres are called:

 A. A fibres. 

B. B fibres. 

C. C fibres. 

D. D fibres.

The correct answer is:

C. C fibres

Explanation: C fibres are small, unmyelinated nerve fibers that conduct pain signals slowly. They are primarily responsible for transmitting dull, burning, or aching pain (slow pain) and are involved in the prolonged, less localized pain sensation.

A fibres: Include A-delta fibers, which are myelinated and transmit sharp, localized pain quickly (fast pain).

B fibres: Small, myelinated fibers mainly involved in autonomic functions.

D fibres: This category does not exist in standard nomenclature for nerve fibers.