MDS PREP
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
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.
Ideally, Orthodontic traction to pull an impacted tooth to line of arch should begin at
1) 2-3 months post surgically
2) As soon as possible after surgery
3) After a waiting period of at least1.5 months
4) Only the method of traction is critical, not the time
Orthodontics Answer: 2
SOLUTION
Mechanical approaches for aligning unerupted teeth. Orthodontic traction to pull an unerupted tooth toward the line of the arch should begin as soon as possible after surgery
Ideally a fixed orthodontic appliance should already be in place before the unerupted tooth is exposed, so that orthodontic force can be applied immediately.
If this is not practical, active orthodontic movement should being no later than 2 or 3 weeks post-surgically.
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.
The diameter of labial-bow of the maxillary plate
1) 0.5-0.6 mm
2) 0.6-0.8 mm
3) 0.7-0.8 mm
4) 0.8-1.0 mm
Orthodontics
Answer: 3
The labial bow is a component of the maxillary denture framework that helps in stabilizing the denture and providing support. The diameter of the labial bow is typically measured to ensure proper fit and function. The standard range for the diameter of the labial bow is generally accepted to be between 0.7 mm and 0.8 mm
Relative to a heterogenous population the incidence of malocclusion in a homogenous population is
1. lower
2. slightly higher
3. significantly higher
4. about the same
Orthodontics
Answer: 1
In a homogeneous population, the genetic variation is less compared to a heterogeneous population. Malocclusion is influenced by both genetic and environmental factors. A homogenous population, which is more genetically similar, would be expected to have a more uniform expression of dental traits, including a lower incidence of malocclusion, assuming that the specific genetic factors for malocclusion are not prevalent in that particular population. In a heterogeneous population, the greater genetic diversity can lead to a higher incidence of malocclusion due to a wider range of genetic combinations contributing to dental misalignments.
Considering the 3D growth of the face, it ceases last in which direction?
1. A-P
2. sagittal
3. transverse
4. vertical
Orthodontics
Answer: 4
for facial growth order of growth is
width > depth > height
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.