Molar relation in primary dentition is determined by:

 # Molar relation in primary dentition is determined by:

A. Mesiobuccal cusp of maxillary first molar

B. Buccal groove of mandibular first molar

C. Distal surface of maxillary and mandibular second molar

D. Distal surface of maxillary and mandibular first molar

The correct answer is:

C. Distal surface of maxillary and mandibular second molar

Explanation:

In primary dentition, the molar relationship is determined by the alignment of the distal surfaces of the maxillary and mandibular second molars. This is used to describe the primary occlusion as either:

Flush terminal plane: The distal surfaces of the second molars are aligned in a straight plane.

Mesial step: The mandibular second molar’s distal surface is mesial to the maxillary second molar’s distal surface.

Distal step: The mandibular second molar’s distal surface is distal to the maxillary second molar’s distal surface.

These relationships are important because they influence the development of the permanent molar occlusion.

Clinical sign that is always positive in bone fracture is:

 # Clinical sign that is always positive in bone fracture is:

A. Crepitus

B. Tenderness

C. Abnormal mobility

D. All of the above

The correct answer is:

B. Tenderness

Explanation:
Tenderness is always present in fractures, as it reflects localized periosteal irritation and soft tissue damage.

Other signs, such as:

• Crepitus and abnormal mobility, may not be present in minor or incomplete fractures. These are typically seen in displaced or severe fractures but are not universal findings.

Endocrine disorder is the primary cause of:

 # Endocrine disorder is the primary cause of:

A. Acromegaly

B. Albright’s syndrome

C. Paget’s disease

D. Fibrous dysplasia

The correct answer is A. Acromegaly.

Explanation:

Acromegaly is primarily caused by an endocrine disorder, specifically excess growth hormone (GH) secretion, usually due to a pituitary adenoma. This leads to abnormal growth of bones and soft tissues, particularly in adults.

Other options explained:

B. Albright’s syndrome (McCune-Albright Syndrome): A genetic disorder caused by post-zygotic mutations in the GNAS gene, leading to fibrous dysplasia, café-au-lait spots, and endocrine abnormalities. It is not primarily an endocrine disorder but has endocrine manifestations.

C. Paget’s disease: A bone remodeling disorder of unclear etiology, possibly involving genetic and environmental factors, not primarily endocrine.

D. Fibrous dysplasia: A developmental bone disorder caused by activating mutations in the GNAS gene, not related to endocrine dysfunction as a primary cause.

The view which best demonstrates inflammation and temporomandibular joint effusion are:

 # The view which best demonstrates inflammation and temporomandibular joint effusion are:

A. T2 weighted MR images

B. T1 weighted MR images

C. Lateral tomogram

D. Panoramic radiograph

The correct answer is:

B. Unilateral and bilateral crossbite

Explanation:
After cleft palate repair, patients often experience unilateral or bilateral crossbite due to maxillary growth deficiencies. Surgical intervention and scarring can inhibit the forward and lateral growth of the maxilla, leading to discrepancies between the maxillary and mandibular arches. This results in crossbites, which are common in individuals with repaired cleft palate.

Other options explained:

• A. Normal occlusion: Rarely achieved without orthodontic intervention due to maxillary growth issues.
• C. Anterior open bite: Not a typical finding unless associated with other conditions or habits.
• D. Anterior deep bite: Uncommon in cleft palate cases as the maxillary hypoplasia usually prevents such occlusion.

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.