MDS PREP
Which of the following forces best accomplish orthodontic tooth movement?
1) Heavy and continuous
2) Heavy and intermittent
3) Light and continuous
4) Light and intermittent
Orthodontics Answer: 3
SOLUTION
Light and continuous
Use of continuous light force is recommended to be applied for adult group of patient rather than intermittent force as applied by removable appliance. This is because continuous forces are expected to bring about direct resorption of the root socket. They should hence not occlude more than a small percentage of blood vessels with in the periodontal ligament, not substantially interfere with their nutritional supply and little interference
with normal biologic functioning. In adult due to heavy force teeth may devitalize because the opening into the tooth (apical foramen) is smaller and blood vessels can be easily disrupted.
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
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 Sunday bite related to?
1) Angle’s class I with anterior open bite
2) Angle’s class I with anterior deep bite and posterior cross bite (unilateral)
3) Angle’s class II
4) Angle’s class III
Orthodontics Answer: 3
SOLUTION
Children and adults with a skeletal Class II relationship and an underlying skeletal Class II jaw relationship position the mandible forward in a “Sunday bite,” making the occlusion look better than it really is.
If a coil and tag of a palatal canine retractor are placed too far distally
1) Base plate is weakend
2) Tooth movement will be slowed
3) Tooth will tend to be moved buccally
4) Tooth will tend to be moved palatally
Orthodontics
Answer: 3
If the coil and tag of a palatal canine retractor are placed too far distally,
the force applied will tend to move the tooth buccally
(toward the cheek) rather than palatally (toward the
palate), which can hinder the intended movement.
Premature exfoliation of primary mandibular canine is most often the sequelae of:
1) Caries
2) Trauma
3) Serial tooth extraction
4) Arch length inadequacy
Orthodontics Answer: 4
SOLUTION
The two major symptoms of severe crowding in the early mixed dentition are severe irregularity of the erupting permanent incisors and early loss of primary canines caused by eruption of the permanent lateral incisors. The children with the largest arch length discrepancies often have reasonably well aligned incisors in the early mixed dentition, because both primary canines were lost when the lateral incisors erupted
After a definitive analysis of the profile and incisor position, these patients face the same decision as those with moderate crowding; whether to expand the arches or extract permanent teeth. In the presence of severe crowding, limited treatment of the problem will not be sufficient and permanent tooth extraction is most likely the best alternative.
How/where should the wire be bent to activate a correctly made palatal canine retraction?
1) Between the coil and tooth, but close to the coil
2) Between the coil and tooth, but close to the tooth
3) Between the coil and its insertion into the base of the plate
4) By opening out the coil
Orthodontics
Answer: 1
Bending the wire between the coil and the tooth, but closer to the coil, allows for effective activation of the retraction mechanism, providing the necessary force for movement.
Heat hardening is done in which orthodontic wire
1) Elgiloy
2) Stainless steel
3) TMA
4) NiTi
Orthodontics Answer: 1
SOLUTION
Elgiloy (Cobalt-Chromium) alloy is supplied in a softer state and can be heat hardened.
After hardening heat treatment, the softest elgiloy becomes equivalent to regular stainless steel.