Most common cause of multiple fetal anomalies is:

 # Most common cause of multiple fetal anomalies is:

A. Syphilis

B. Tetracycline

C. Rubella

D. Rubeola

The correct answer is C. Rubella.

The correct answer is:

C. Rubella

Explanation:

Rubella, especially when contracted during the first trimester of pregnancy, is a significant cause of multiple fetal anomalies. This is due to its teratogenic effects, which can result in congenital rubella syndrome (CRS). The anomalies caused by CRS can include:

• Cardiac defects (e.g., patent ductus arteriosus, pulmonary artery stenosis)
• Ocular defects (e.g., cataracts, retinopathy, glaucoma)
• Auditory defects (e.g., sensorineural hearing loss)
• Neurological defects (e.g., microcephaly, developmental delays)

Other options:

• A. Syphilis: Can cause congenital syphilis with specific anomalies (e.g., skeletal deformities, Hutchinson teeth), but it is not the most common cause of multiple fetal anomalies.
• B. Tetracycline: Causes specific anomalies, mainly involving dental staining and hypoplasia, not a wide range of fetal anomalies.
• D. Rubeola (measles): While it can cause complications in pregnancy, it is less associated with multiple fetal anomalies compared to rubella.

Rubella is particularly significant due to its potential to cause a broad spectrum of anomalies when maternal infection occurs early in pregnancy.

Mean diameter of inferior alveolar nerve is:

 # Mean diameter of inferior alveolar nerve is:

A. 10 mm

B. 4.7 mm

C. 8 mm

D. 1.7 mm

The correct answer is B. 4.7 mm.

The inferior alveolar nerve is a branch of the mandibular nerve (the third division of the trigeminal nerve), responsible for providing sensory innervation to the lower teeth, chin, and lower lip. Its diameter is significant in clinical practices like dental anesthesia, nerve preservation during surgeries, and implant placement.

• The mean diameter of 4.7 mm reflects the nerve's size as it travels through the mandibular canal.

Inferior Alveolar – exits the mental foramen as the mental nerve and continues as the incisive nerve.

● The nerve to mylohyoid is a motor and sensory branch of the inferior alveolar nerve

● The nerve to anterior belly of the digastric muscle is a motor branch of the inferior alveolar nerve

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.