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.
Facial profile of a typical mouth breather is
1) Long and wide
2) Short and wide
3) Long and narrow
4) Short and narrow
Orthodontics Answer: 3
SOLUTION
Altered respiratory pattern, such as breathing through the mouth rather than the nose, could change the posture of the
head, jaw, and tongue. This in turn could alter the equilibrium of pressures on the jaws and teeth and affect both jaw growth and tooth position.
In order to breathe through the mouth, it is necessary to lower the mandible and tongue, and extend (tip back) the head.
If these postural changes were maintained, face height would increase, and posterior teeth would super-erupt;
unless there was unusual vertical growth of the ramus, the mandible would rotate down and back, opening the bite
anteriorly and increasing overjet; and increased pressure from the stretched cheeks might cause a narrower maxillary dental arch.
If maxillary canines are placed forward to orbital plane, they are said to be in
1) Protraction
2) Retraction
3) Abstraction
4) Contraction
Orthodontics Answer: 1
SOLUTION
Simon used the orbital plane (a plane perpendicular to the F-H plane at the margin of the bony orbit directly under the pupil of the eye).
According to Simon, in normal arch relationship, the orbital plane passes through the distal axial aspect of the maxillary canine
Malocclusions described as anteropostenor deviations based on their distance from the orbital plane are as follows:
1. Protraction: The teeth, one or both, dental arches, andYor jaws are too far forward, i.e. placed forward or anterior to the plane as compared to the normal where the plane passes through the distal incline of the canine.
2. Retraction: The teeth, one or both dental arches and/or jaws are too far backward, i.e. placed posterior to the plane than normal
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.
What is the relation of the lower first molar to the upper first molar in an
Angle Class III malocclusion?
1. distal
2. lateral
3. mesial
4. normal
Orthodontics Answer: 3
Angle Class III Malocclusion:
Angle Classification:
The Angle classification system, developed by Edward Angle, is a
widely used method for categorizing malocclusions based on the
relationship of the first molars and the canines.
Class III Malocclusion:
In Angle Class III malocclusion, the lower first molar is positioned
more mesially (toward the midline) relative to the upper first molar.
This means that when the first molars are in occlusion, the lower first
molar is ahead of the upper first molar.
Clinical Implications:
Class III malocclusion is often associated with a prognathic
mandible (where the lower jaw is positioned forward) or a retruded
maxilla (where the upper jaw is positioned backward). This can lead to
various functional and aesthetic concerns, including difficulties with
biting and chewing, as well as facial profile changes.
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.
Analysis which is similar to Pont’s analysis is_______?
1) Linder Harth index
2) Korkhaus analysis
3) Bolton’s analysis
4) (A) and (B)
Orthodontics Answer: 4
SOLUTION
· Pont’s in 1905 presented a system whereby the measurement of the four maxillary incisors automatically established the width of the arch in the premolar and molar region. If measured value is less than calculated value, it indicates the need for expansion.
· Linder Harth index: This analysis is very similar to Pont’s analysis except that a new formula has been proposed to determine the calculated premolar and molar value.
· Korkhaus analysis: This analysis is also very similar to Pont’s analysis it makes use of Linder Harth’s formula to determine the ideal arch width in the premolar and molar region.
In addition this analysis utilizes a measurement made from the midpoint of the inter-premolar line to a point in between the two maxillary incisors.
· Bolton’s analysis: The Bolton’s analysis helps in determining disproportion in size between maxillary and mandibular teeth.
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