MDS PREP
In orthodontic treatment, the forces applied should not exceed the ________________ in order to avoid injuries to the tissues.
1) Arterial blood pressure
2) Muscular forces of facial muscles
3) Masticatory retrusion
4) Capillary blood pressure
Orthodontics Answer: 4
SOLUTION
Optimum orthodontic force is one, which moves teeth most rapidly in the desired direction, with the least possible damage to tissue and with minimum patient discomfort.
Oppenheim and Schwarz following extensive studies stated that the optimum force is equivalent to the capillary pulse pressure, which is 20-26 gm/sq. cm of root surface area.
From a clinical point of view, optimum orthodontic force has the following characteristics:
1) Products rapid tooth movement
2) Minimal patient discomfort
3) The lag phase of tooth movement is minimal
4) No marked mobility of the teeth being moved
From a histologic point of view the use of optimum orthodontic force has the following characteristics:
1) The vitality of the tooth and supporting periodontal ligament is maintained
2) Initiates maximum cellular response
3) Produces direct or frontal resorption
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.
Relapse of orthodontic tooth rotation is due to periodontal traction. This is mainly caused by action of which periodontal fibers
1) Supracrestal fibres and oblique fibres
2) Supracrestal fibres and horizontal fibres
3) Supracrestal fibres and transeptal fibres
4) Transeptal fibres and oblique fibres
Orthodontics Answer: 3
PDL traction is mainly due to supracrestal fibres, transeptal fibres of gingival fibers.
It needs at least 232 days for readaptation, e.g. rotations.
To avoid relapse either circumferential supracrestal fibrotomy is done OR a prolonged retention is given.
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.
What dental relationship is present in an Angle Class I occlusion?
Orthodontics Answer: 3
1. The buccal cusp of the maxillary second premolar aligns with the mesiobuccal groove of the mandibular first molar.
2. The cusp of the maxillary canine aligns with the cusp of the mandibular canine.
3. The mesiobuccal cusp of the maxillary first molar aligns with the mesiobuccal groove of the mandibular first molar.
4. The mesiobuccal cusp of the maxillary first molar aligns with the embrasure between the mandibular first molar and second premolar.
The mesiobuccal cusp of the maxillary first molar aligns with the mesiobuccal groove of the mandibular first molar.
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
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.
Crowding that occurs after age of 18 is the result of
1) Impacted third molar
2) Physiological maturational change
3) Orthodontic relapse
4) Periodontal disease
Orthodontics
Answer: 2
Crowding that occurs after age 18 is typically the result of physiological maturational changes.
Explanation: Dental crowding is a common malocclusion where teeth do not have enough space to align properly in the dental arch. After the age of 18, most of the facial growth has concluded, and the teeth are fully erupted. If crowding occurs at this stage, it is most likely due to physiological maturational changes, such as the natural movement of teeth or the eruption of third molars (wisdom teeth). Impacted third molars are another potential cause of late crowding, but the question specifies that the crowding is not due to them. Orthodontic relapse is a possibility if the individual had prior orthodontic treatment, but without that context, the most likely cause for new crowding in adulthood is the natural shifting of teeth over time or the late eruption of wisdom teeth. Periodontal disease can affect tooth positioning, but it does not directly cause crowding.