CDT Prosthodontic & Orthodontic Appliance Fabrication 1 — Questions and Answers

Question 1: What is the purpose of a dental retainer?

To whiten teeth.
To maintain alignment after braces (Correct answer)
To strengthen the gums.
To aid chewing efficiency.

Correct answer: To maintain alignment after braces

After orthodontic treatment with braces, teeth have a natural tendency to shift back towards their original positions, a phenomenon known as relapse. A dental retainer is an appliance, either removable or fixed, worn to hold the teeth in their newly corrected alignment. This stabilizes the surrounding bone and tissues, preserving the orthodontic results and maintaining the desired tooth position long-term.

Question 2: Which material is commonly used in denture bases?

Gold alloy.
Acrylic resin (Correct answer)
Zinc oxide.
Copper.

Correct answer: Acrylic resin

Acrylic resin, specifically polymethyl methacrylate (PMMA), is the most commonly used material for fabricating denture bases. Its popularity stems from its excellent aesthetics, as it can be colored to closely match natural gum tissue, and its ease of processing. Acrylic resin is also biocompatible, relatively lightweight, and durable, providing a comfortable and functional foundation for artificial teeth.

Question 3: What is a common reason for relining a denture?

To change tooth color.
To improve fit due to tissue changes (Correct answer)
To increase biting force.
To make it heavier.

Correct answer: To improve fit due to tissue changes

Over time, the bone and soft tissues in a patient's mouth can resorb and change shape, causing a denture to become loose and ill-fitting. Relining involves adding new acrylic material to the tissue-fitting surface of the denture base to re-establish a snug and comfortable fit. This process improves the denture's retention and stability, enhancing comfort and function without requiring the fabrication of an entirely new denture.

Question 4: What is the main function of orthodontic brackets?

To bleach teeth.
To support the archwire and guide teeth movement (Correct answer)
To protect gums.
To reduce tooth sensitivity.

Correct answer: To support the archwire and guide teeth movement

Orthodontic brackets are small attachments bonded to the surface of teeth, serving as crucial anchors for the archwire. The archwire, which is threaded through these brackets, applies gentle, continuous forces that are transmitted to the teeth. This controlled force guides the teeth into their desired, corrected positions over time, facilitating effective orthodontic tooth movement.

Question 5: Which appliance is used to expand the upper jaw?

Headgear.
Palatal expander (Correct answer)
Nightguard.
Space maintainer.

Correct answer: Palatal expander

A palatal expander is an orthodontic appliance specifically designed to gradually widen the upper jaw (maxilla) when it is too narrow. This is often necessary to correct a crossbite or create more space for crowded teeth. The expander works by applying gentle outward pressure to the two halves of the upper jaw, separating them at the midpalatal suture over a period of weeks or months.

Question 6: What material is commonly used for orthodontic wires?

Aluminum.
Stainless steel or nickel-titanium (Correct answer)
Lead.
Plastic.

Correct answer: Stainless steel or nickel-titanium

Orthodontic wires are primarily fabricated from stainless steel or nickel-titanium (NiTi) alloys, chosen for their specific mechanical properties. Stainless steel wires offer good strength and formability, while NiTi wires are renowned for their superelasticity and shape memory. These properties allow NiTi wires to exert continuous, gentle forces over extended periods, making them highly effective for precise tooth movement during orthodontic treatment.

Question 7: Why are dental impressions important for appliance fabrication?

To determine tooth color.
To capture detailed anatomical information for appliances (Correct answer)
To check for tooth decay.
To test gum health.

Correct answer: To capture detailed anatomical information for appliances

Dental impressions are vital for appliance fabrication because they capture a precise negative mold of the patient's oral structures, including teeth, gums, and surrounding tissues. This detailed anatomical information is indispensable for creating custom-fit dental appliances such as crowns, bridges, dentures, and orthodontic devices. Accurate impressions ensure that the final appliances are precise, functional, and comfortable for the patient.

Question 8: What process strengthens a metal framework for a partial denture?

Polishing.
Casting (Correct answer)
Cooling.
Painting.

Correct answer: Casting

Casting is the fundamental process that strengthens a metal framework for a partial denture. In this technique, molten metal alloy is injected into a precise mold created from a wax pattern, allowing it to solidify into the exact desired shape. This process transforms the wax pattern into a strong, rigid metal structure capable of withstanding the forces of chewing and providing durable support for the artificial teeth and acrylic base.

Question 9: Why are space maintainers used in pediatric dentistry?

To whiten teeth.
To maintain space for permanent teeth after premature loss (Correct answer)
To increase chewing force.
To reduce cavities.

Correct answer: To maintain space for permanent teeth after premature loss

Space maintainers are crucial in pediatric dentistry to prevent complications when a primary (baby) tooth is lost prematurely. If a primary tooth is lost too early, adjacent teeth can drift into the empty space, blocking the eruption path of the permanent tooth underneath. A space maintainer holds this space open, ensuring the permanent tooth has sufficient room to erupt correctly and preventing future orthodontic problems.

CDT Prosthodontic & Orthodontic Appliance Fabrication 1

What is the purpose of a dental retainer?