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.

Premature loss of primary teeth, sharply marginated lucency, round cell infiltrate with numerous eosinophils

# A 12 year old patient presents with premature loss of primary teeth. On radiographic examination, a sharply marginated lucency is seen in the area of tooth loss. A biopsy specimen shows a round cell infiltrate with numerous eosinophils. Which of the following diagnosis is suggested?

A. Cherubism B. Gardener’s syndrome C. Fibrous dysplasia D. Langerhans’ cell disease

The correct answer is D. Langerhans’ cell disease.

Explanation: The clinical presentation of a 12-year-old patient with premature loss of primary teeth, a sharply marginated radiolucency on radiographic examination, and a biopsy showing a round cell infiltrate with numerous eosinophils strongly suggests Langerhans’ cell disease (also known as Langerhans cell histiocytosis, LCH). LCH is a rare disorder characterized by the proliferation of Langerhans cells, often affecting children. In the oral cavity, it commonly presents with premature tooth loss, "floating teeth" due to bone destruction, and sharply defined radiolucent lesions. The biopsy finding of a round cell infiltrate with eosinophils is characteristic, as LCH lesions often contain Langerhans cells (which appear as round cells) and a prominent eosinophilic infiltrate.

Explanation of other options:

• A. Cherubism: This is a genetic condition causing bilateral jaw swelling due to fibrous tissue replacement of bone, typically presenting with multilocular radiolucencies and a "cherubic" facial appearance. It is not typically associated with premature tooth loss or eosinophilic infiltrates.
• B. Gardner’s syndrome: This is a variant of familial adenomatous polyposis, associated with osteomas, supernumerary teeth, and colorectal polyps. It does not typically cause premature tooth loss or sharply marginated radiolucencies with eosinophilic infiltrates.
• C. Fibrous dysplasia: This condition involves the replacement of normal bone with fibrous tissue, leading to expansile, ground-glass radiopaque lesions rather than sharply marginated radiolucencies. It is not associated with eosinophilic infiltrates or premature tooth loss.

Thus, Langerhans’ cell disease best fits the described clinical, radiographic, and histologic findings.