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.

Enzyme marker of acute alcohol toxicity

 # A person with a long history of alcohol intake reports with acute alcohol intoxication. Which of the following enzymes is a marker of acute toxicity?

A. AST

B. ALT

C. GGT

D. Alkaline phosphatase

The correct answer is:

C. GGT (Gamma-Glutamyl Transferase)

Explanation:
Gamma-glutamyl transferase (GGT) is a sensitive marker for alcohol consumption and acute alcohol toxicity. It is elevated in conditions involving liver damage, particularly from chronic alcohol use. While AST and ALT may also be elevated in liver damage, GGT is more specific for alcohol-related effects. Alkaline phosphatase is primarily associated with biliary obstruction or bone disorders.

Calcium hydroxide applied directly to the exposed pulp to preserve its vitality

 # A patient with pulp exposure has calcium hydroxide applied directly to the exposed pulp to preserve its vitality. What is this procedure called?

A. Indirect pulp capping

B. Partial pulpotomy

C. Direct pulp capping

D. Cvek pulpotomy

The correct answer is:

C. Direct pulp capping

Direct pulp capping involves the application of a biocompatible material, such as calcium hydroxide, directly onto an exposed pulp to preserve its vitality and encourage the formation of reparative dentin.

Soreness of the muscles after wearing the denture for sometime

 # A newly fabricated complete denture patient reports with the complaint of soreness of the muscles after wearing the denture for sometime. What could be the probable cause?

A. Increased interocclusal space

B. Decreased interocclusal space

C. Excessive muscular force on the denture

D. Repeated muscle trauma

The correct answer is: B. Decreased interocclusal space

Explanation:

Soreness of the muscles after wearing newly fabricated complete dentures is often due to a decreased interocclusal space (or excessive occlusal vertical dimension). When the interocclusal space is inadequate:

1. The denture teeth are set too far apart, increasing the vertical dimension of occlusion (VDO).
2. This forces the muscles of mastication to remain overly contracted, leading to muscle fatigue and soreness over time.
3. The patient may also experience difficulty closing their mouth comfortably or feel that the dentures are "too tall."

Other options:

• A. Increased interocclusal space: Excessive interocclusal space (reduced VDO) might cause overclosure of the jaws but typically leads to different problems like angular cheilitis and lack of proper function, rather than muscle soreness.
• C. Excessive muscular force on the denture: While excessive force can cause issues, it is usually secondary to improper fit or function, not a primary cause related to soreness.
• D. Repeated muscle trauma: This is uncommon with new dentures unless associated with improper extension or faulty design, but it is not the primary explanation in this case.

Key Takeaway:

Proper assessment of the vertical dimension and interocclusal space is crucial in denture fabrication to avoid muscular discomfort and ensure comfort during function.

 # RPI clasp in a distal extension cast partial denture:

A. Used for buccally tilted molar

B. Provides push type retention

C. Provides pull type retention

D. Is contraindicated

The correct answer is:

B. Provides push type retention

Explanation:

The RPI clasp (Rest, Proximal plate, I-bar) system in a distal extension removable partial denture provides push-type retention because the I-bar clasp moves in a downward direction towards the gingiva when the denture base moves occlusally during function. This ensures that forces are directed in a manner that minimizes torque on the abutment tooth and enhances tissue support.

Breakdown of Key Features:

1. Rest: Positioned mesially to redirect forces along the long axis of the abutment tooth.
2. Proximal Plate: Contacts the guiding plane to stabilize the denture and control path of insertion and removal.
3. I-bar clasp: Engages an undercut and moves gingivally (pushes) as the denture is seated or when occlusal forces displace the denture base.

The push-type action of the I-bar helps maintain a stress-relieving design by allowing movement and reducing torque on the abutment during function.