MDS PREP
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.
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.
The first ossification center of the mandible in six weeks old human embryo is found in which of the following locations
1) Future coronoid process
2) Future condylar process
3) Future mental foramen
4) Future mandibular foramen
Orthodontics Answer: 3
SOLUTION
The mandible is ossified in the fibrous membrane covering the outer surfaces of Meckel’s cartilages.
These cartilages form the cartilaginous bar of the mandibular arch, and are two in number, a right and a left.
Ossification takes place in the membrane covering the outer surface of the ventral end of Meckel’s cartilage , and each half of the bone is formed from a single center which appears, near the mental foramen, about the sixth week of fetal life.
By the tenth week the portion of Meckel’s cartilage which lies below and behind the incisor teeth is surrounded and invaded by the membrane bone
The basic principle of Orthodontic spot welder lies on the concept of :-
1 Heat technique
2) Quenching
3) Diodelasers
4) Electrode Technique
Orthodontics Answer: 4
SOLUTION
The type of welding used to join Orthodontic components is called Spot welding. The heat source usually a high amperage electricity. Orthodontic spot welders employ the electrode technique, in which current is conducted through two copper electrodes. The copper electrode in a welding unit serve the following purposes :
1. Transmit current to the metals to be joined so as to cause a rapid increase in temperature.
2. The electrodes help in conducting the heat produced away from the area so as to preserve the properties of stainless steel around the weld spot.
3. The electrode also help in holding together the two metals to be joined.
4. The electrodes are designed to apply pressure on the metals being joined. As soon as the temperature increases, the pressure exerted by the electrodes helps in squeezing metal into each other.
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.
Servo system theory of Grown was given by
1) Scott
2) Petrovic
3) Limborgh
4) Vander Kaauw
Orthodontics
Answer: 2
The servo system theory, which relates to the control mechanisms in orthodontics, was proposed by Petrov ic (option 2). This theory helps in understanding how forces applied to teeth can be controlled and adjusted to achieve desired tooth movements during orthodontic treatment.
A single force applied at which point of a tooth will allow complete translation of the tooth.
1) At the apex
2) At the incisal edge
3) At the center of resistance
4) At the center of rotation
Orthodontics Answer: 3
SOLUTION
Center of resistance- Point analogous to the centers of gravity.
Generally it is constant.In single root it lies between one third and one half of the root apical to alveolar crest.
In multi rooted tooth it lies 1-2 mm apical to furcation
Baker anchorage utilizes
1) Intermaxillary anchorage with screws
2) Intramaxillary anchorage with screws
3) Intermaxillary anchorage with elastics
4) Intramaxillary anchorage with elastics
Orthodontics Answer: 3
SOLUTION
Intermaxillary anchorage or Baker's Anchorage. This type of anchorage involves using elastics from one jaw to the other, in the form of either Class 2 elastics (moving upper teeth back) where lower molar teeth serve as anchors, or Class 3 elastics (moving lower teeth back) where upper molars serve as anchors.
Intramaxillary anchorage is also used in the form of E-chain, when elastics are used from the back molar teeth to the front teeth in the same jaw to move teeth back of the mouth.