Type of crowding that is genetically determined and is caused by disproportionately sized teeth and jaws:

Type of crowding that is genetically determined and is caused by disproportionately sized teeth and jaws:

A. Primary crowding

B. Secondary crowding

C. Tertiary crowding

D. Environmental crowding

The correct answer is A. Primary crowding. 

Primary crowding refers to a type of dental crowding caused by a genetic discrepancy in tooth and jaw sizes, such as larger teeth relative to the jaw, leading to misalignment. This contrasts with secondary crowding, which results from environmental factors like early tooth loss, and tertiary crowding, which involves late-stage incisor irregularities. Environmental crowding isn't a standard classification but aligns with secondary causes.

Which of the following is the least biocompatible?

Which of the following is the least biocompatible?

A. TMA

B. Elgiloy

C. Stainless steel

D. Cu-NiTi

The correct answer is B. Elgiloy.

Elgiloy (a cobalt-chromium-nickel alloy) is the least biocompatible among the options due to its higher nickel content (14-16%) compared to stainless steel (8%), leading to greater nickel and chromium ion release in simulated oral environments. Studies show it induces significant neurotoxicity via necrosis, elevated oxidative stress, and higher cytotoxicity (2.7-fold increase in dead cells) relative to stainless steel (apoptosis, 1.7-fold dead cells), TMA (variable but generally low ion release and non-toxic), and Cu-NiTi (lower ion release and minimal cytotoxicity). This increases risks of allergic reactions and tissue irritation in orthodontic use.

What is facial divergence?

 # What is facial divergence?

A. Relation of maxilla to mandible

B. Lower face inclination in relation to the forehead

C. Relation of mandible to forehead

D. Relation of lower face with cranial base

The correct answer is B. Lower face inclination in relation to the forehead

Examination of facial divergence is done by viewing the patient from the side. Facial divergence is often influenced by patient’s ethnicity and racial background. For instance, convex profile with an anterior facial divergence is a normal feature of negroid race groups. Facial divergence is defined as an anterior or posterior inclination of mandible (lower face) relative to the forehead. Assessment of facial divergence is done by a line drawn from the forehead to the chin. Facial divergence of an individual may fall into any one of the following three types: 1. Straight/orthognathic—A line drawn from forehead to chin is almost straight. 2. Anterior facial divergence—The line drawn from forehead to the chin is inclined anteriorly. 3. Posterior facial divergence—The line drawn from forehead to the chin is inclined posteriorly.

Which radiographic landmark extends inferiorly from the medial pterygoid plate?

 # Which radiographic landmark extends inferiorly from the medial pterygoid plate?

A. Nasolabial fold

B. Hamular process

C. Zygomatic process

D. Maxillary tuberosity

The correct answer is B. Hamular process.

The radiographic landmark that extends inferiorly from the medial pterygoid plate is the hamulus (or hamular process) of the sphenoid bone.

The hamular process is a small, hook-like projection that extends downward from the medial pterygoid plate. It is visible on certain radiographic views, such as panoramic or lateral cephalometric radiographs, and serves as an attachment point for structures like the pterygomandibular raphe and the tensor veli palatini muscle.