MDS PREP
Which dimension in which arch is considered as a safety value for pubertal growth spurts?
1) Maxillary intercanine dimension
2) Mandibular intercanine dimension
3) Maxillary intermolar width
4) Mandibular intermolar width
Orthodontics Answer: 1
SOLUTION
Intercanine width serves as safety valve for dominant horizontal basal mandibular growth spurt.
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.
All of the following factors interfere with statural growth on long-term basis except
1) Cleft palate
2) Poor nutrition
3) Chronic diseases
4) Cardiac diseases
Orthodontics
Answer: 1
A cleft palate is a congenital condition that does not inherently affect statural growth. The other factors listed—poor nutrition, chronic diseases, and cardiac diseases—can all have long-term negative impacts on a person's growth and development. Poor nutrition can lead to stunted growth due to insufficient nutrients for bone and tissue development, while chronic diseases and cardiac diseases can impair the body's ability to regulate growth hormones and overall health, potentially leading to growth delays or abnormalities.
Which of the following cannot be used for incisor retraction
1) Roberts retractor
2) Split labial-bow
3) High labial-bow
4) Apron spring
Orthodontics
Answer: 3
The high labial-bow is typically used for molar retraction and is not designed for incisor retraction. In contrast, Roberts retractors, split labial-bows, and apron springs are all instruments that can be used effectively for retracting incisors during orthodontic treatment.
What is force applied per unit area?
1) Strain
2) Stress
3) Couple
4) Center of resistance
Orthodontics Answer: 2
SOLUTION
Stress is the force applied per unit area while strain can be defined as the internal distortion per unit area.
Stress and strain are inter-related terms as stress is an external force acting upon a body while strain is the resultant of stress on that body.
Strain can be expressed in the form of a change in either the external dimension or internal energy of the body.
Supervision of child"s dentition is critical at or in
1) 3-6 years primary dentition
2) 7-10 years mixed dentition
3) 11-14 years permanent dentition
4) 14-17 years post permanent
Orthodontics
Answer: 2
Supervision of a child's dentition is critical during all developmental stages, but the 7-10 years age range, which is the mixed dentition stage, is a particularly important time for monitoring. This is because it is the period when both primary (baby) and permanent (adult) teeth are present in the mouth. During this stage, children are at risk for various dental problems such as crowding, malocclusion, and the loss of primary teeth that can affect the eruption of permanent teeth.
In classifying molar relation in patient with premature loss of primary molar, additional relation to be noted is
1) Incisor relation
2) Canine relation
3) Midline relation
4) Premolar relation
Orthodontics Answer: 2
SOLUTION
Which of the fibers attached to cementum are most likely to contribute to relapse of tooth rotation:
1) Gingival group of fibers
2) Apical fibers
3) Horizontal fibers
4) Oblique fibers
Orthodontics Answer: 1
SOLUTION
Gingival group of fibers
Principal fibers of the periodontal ligament rearranges themselves quite rapidly to the position in about 4 weeks.The supra-alveolar gingival fiber take as much as 40 weeks to rearrange around the new position and thus predispose to relapse.