MDS PREP
What is force applied per unit area?
1) Strain
2) Stress
3) Couple
4) Center of resistance
Orthodontics Answer: 2
SOLUTION
Stress is the force applied per unit area while strain can be defined as the internal distortion per unit area.
Stress and strain are inter-related terms as stress is an external force acting upon a body while strain is the resultant of stress on that body.
Strain can be expressed in the form of a change in either the external dimension or internal energy of the body.
The main disadvantage of uprighting first molar with a loop lingual arch is
1) Extrusion of molars
2) Overcorrection of molars
3) Flaring of mandibular incisors
4) All of the above
Orthodontics
Answer: 3
One of the main disadvantages of using a loop lingual arch to upright the first molar is that it can lead to flaring of the mandibular incisors due to the forces applied.
Which one of these is the etiological factors of tongue thrust?
1) Hyposensitive palate
2) Hypertonic orbicularis oris activity
3) Macroglossia
4) All of these
Orthodontics Answer: 4
Etiology of Tongue thrust
Fletcher has proposed the following factors as being the cause for tongue thrusting.
Genetic factors : They are specific anatomic or neuromuscular variations in the oro-facial region that can precipitate tongue thrust. e.g. Hypertonic orbicularies oris activity.
Learned behaviour (habit) : Tongue thrust can be acquired as a habit.
The following are some of the predisposing factors that can lead to tongue thrusting:
a. Improper bottle feeding
b. Prolonged thumb sucking
c. Prolonged tonsillar and upper respiratory tract infections
d. Prolonged duration of tenderness of gum or teeth can result in a change in swallowing pattern to avoid pressure on the tender zone.
Maturational : Tongue thrust can present as part of a normal childhood behaviour that is gradually modified as the age advances. The infantile swallow changes to a mature swallow once the posterior deciduous teeth start erupting.
Sometimes the maturation is delayed and thus infantile swallow persists for a longer duration of time.
Mechanical restrictions : The presence of certain conditions such as macroglossia, constricted dental arches and enlarged adenoids predispose to tongue thrust habit.
Neurological disturbance: Neurological disturbances affecting the oro-facial region such as hyposensitive palate and moderate motor disability can cause tongue thrust habit.
Psychogenic factors : Tongue thrust can sometimes occur as a result of forced discontinuation of other habits like thumb sucking. It is often seen that children who are forced to leave thumb sucking habit often take up tongue thrusting.
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.
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.
The philtrum of the upper lip is formed largely by the
1) Lateral nasal processes
2) Globular process
3) Maxillary processes
4) Mandibular processes
Orthodontics
Answer: 2
Explanation: The philtrum is the vertical groove located in the middle of the upper lip. It is primarily formed by the fusion of the medial nasal processes, which include the globular process. The globular process is a key structure in the embryonic development of the face, contributing to the formation of the upper lip and the philtrum.
Transitional phase of dentition is
1) During eruption of permanent and exfoliation of deciduous teeth
2) After all permanent teeth have erupted
3) Phase during correction of malocclusion
4) None of the above
Orthodontics
Answer: 1
The transitional phase of dentition refers to the period when the primary (deciduous) teeth are being replaced by permanent teeth. This phase is characterized by the simultaneous eruption of permanent teeth and the exfoliation (loss) of primary teeth. It typically occurs between the ages of 6 and 12 years. The other options do not accurately describe this transitional phase; option 2 refers to a post-transitional phase, while option 3 pertains to orthodontic treatment rather than a specific phase of dentition.