MDS PREP
The orthodontic correction of which of the following is most easily retained
1) Anterior cross bite
2) Crowding
3) Diastema
4) Spacing
Orthodontics Answer: 1
SOLUTION
The key to success is to use an appliance that is both comfortable, easily retained and predictable such as a simple Hawley retainer with recurve springs or a fixed labial-lingual appliance (including a vertical removable arch for ease of adjustment with a recurve spring to jump the cross-bite).
Both of these appliances work by tipping the maxillary teeth forward so they are in a normal dental relationship to the mandibular teeth. Once this is accomplished, it will allow future coordinated growth between the maxilla and the mandible
Activation of a reverse labial bow is done by?
1) Opening the loop
2) Compressing the loop
3) Reversing the loop
4) Bending the loop
Orthodontics Answer: 1
Reverse labial bow is so called as activation of the bow is done by opening the U-loop, instead of compressing as is seen in the conventional labial bows.
An increase or decrease in the Y axis is related to:
1) The growth pattern
2) Extrusion of molars
3) Intrusion of molars
4) All of the above
Orthodontics Answer: 1
SOLUTION
The iron carbide in orthodontic wire is in the form of
1) Martensite
2) Ferrite
3) Carbide
4) Austenite
Orthodontics
Answer: 4
Orthodontic wires are often made from stainless steel, which contains iron, carbon, and other alloying elements. The term "iron carbide" refers to a compound of iron and carbon, typically represented as Fe₃C. In the context of orthodontic wires, the microstructure can exist in different phases depending on the temperature and composition. Austenite is a face-centered cubic (FCC) structure that is stable at high temperatures and is known for its ductility and strength. When orthodontic wires are heated during the manufacturing process, they can be formed into austenite, which can then be transformed into martensite upon cooling, providing the wire with desirable properties for orthodontic applications.
Earnest Klein has classified habits into
1) Compulsive and non-compulsive habits
2) Intentional and non-intentional habits
3) Primary and secondary habits
4) Pressure and non-pressure habits
Orthodontics
Answer: 2
Earnest Klein's classification of habits distinguishes between intentional habits (those that are consciously performed) and non-intentional habits (those that occur unconsciously or without deliberate intention). This classification helps in understanding the nature of habits, particularly in the context of dental and orthodontic practices.
Supracrestal fibrotomy is done after correction of:
1) Crowding
2) Proclined incisors
3) Severely rotated teeth
4) Space closure
Orthodontics Answer: 3
Solution
Circumferential supracrestal fibrotomy (CSF) eliminates the pull of the stretched supracrestal gingival fibres which are the major cause of orthodontic relapse.
The pain after the application of force after activation during fixed mechanotherapy is likely to disappear within how much time ?
1) 24 hours
2) 2 to 4 days
3) 4 to 8 days
4) 10 days
Orthodontics Answer: 2
SOLUTION
If heavy pressure is applied to a tooth, pain develops almost immediately as the PDL is literally crushed.
There is no excuse for using force levels for orthodontic tooth movement that produce immediate pain of this type.
If appropriate orthodontic force is applied, the patient feels little or nothing immediately. Several hours later, however, pain usually appears. The patient feels a mild aching sensation, and the teeth are quite sensitive to pressure, so that biting a hard object hurts.
The pain typically lasts for 2 to 4 days, and then disappears until the orthodontic appliance is reactivated. At that point, a similar cycle may recur, but for almost all patients, the pain associated with the initial activation of the appliance is the most severe.
Bone tissue grows by
1) Apposition
2) Interstitial growth
3) Osteoclastic growth
4) Mesenchymal tissue growth
Orthodontics Answer: 1
SOLUTION
Interstitial growth, simply means that it occurs at all points within the tissue. When mineralization takes place so that hard tissue is formed, interstitial growth becomes impossible.