MDS PREP
Which of the following is not one of the consequences of using Herbst appliance in treatment of Class II malocclusion?
1) Increase in mandibular growth
2) Over corrected Class I molar relation
3) Increase in SNB angle
4) Increase in overjet
Orthodontics Answer: 4
Solution
The following are the effects when Herbst appliance used for treatment of Class II malocclusion:
1. Class I molar relation or over-corrected Class I molar relation.
2. Increased mandibular growth
3. Distal driving of maxillary molars which helps to achieve molar relation.
4. Reduction of overjet by increasing mandibular length and proclination of mandibular incisors.
5. Inhibitory effect on sagittal maxillary growth
6. Weislander suggested double contour of glenoid fossa which indicates anterior transformation of glenoid fossa
7. Increased SNB angle and decreased SNA angle.
Which dimension in which arch is considered as a safety value for pubertal growth spurts?
1) Maxillary intercanine dimension
2) Mandibular intercanine dimension
3) Maxillary intermolar width
4) Mandibular intermolar width
Orthodontics Answer: 1
SOLUTION
Intercanine width serves as safety valve for dominant horizontal basal mandibular growth spurt.
How much force is usually used to move a tooth with an orthodontic appliance?
- extremely light force, less than 1 gram
- moderate force, in the range of 50 to 150 grams
- very heavy force, greater than 500 grams
- whatever the patient can tolerate
moderate force, in the range of 50 to 150 grams
Activation of a reverse labial bow is done by?
1) Opening the loop
2) Compressing the loop
3) Reversing the loop
4) Bending the loop
Orthodontics Answer: 1
Reverse labial bow is so called as activation of the bow is done by opening the U-loop, instead of compressing as is seen in the conventional labial bows.
If PMBAW% is 44 in Howe"s analysis, it indicates
1) Extraction case
2) Expansion case
3) Borderline case
4) None of the above
Orthodontics
Answer: 3
The primary purpose of Howe's Analysis is to assess the width of the
dental arches and to identify any discrepancies between the maxillary
(upper) and mandibular (lower) arches. This is particularly important in
cases of malocclusion, where the alignment of the teeth and the relationship
between the jaws may be compromised.
The analysis involves measuring specific distances on the dental casts,
including:
Intercanine Width: The distance between the cusp
tips of the canines.
Interpremolar Width: The distance between the cusp
tips of the first premolars.
Intermolar Width: The distance between the cusp
tips of the first molars.
These measurements are used to calculate the Percentage of
Maxillary Buccal Arch Width (PMBAW%), which is a key indicator in
the analysis.
The results of Howe's Analysis can indicate different treatment needs:
Normal Case: A PMBAW% within a certain range
(typically around 50-60%).
Narrow Case: A PMBAW% below the normal range,
indicating a need for arch expansion.
Wide Case: A PMBAW% above the normal range, which
may suggest the need for extraction or other interventions.
Borderline Case: A PMBAW% around 44, indicating
that the arch width is at a threshold where careful consideration is
needed for treatment options.
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.
If the edgewise bracket is not pressed completely on to a tooth on the mesial side while bonding, the side effect would be
1. intrusion
2. extrusion
3. rotation
4. breakage of bracket
Orthodontics
Answer: 3
we are applying force distally only..force vector will rotate the tooth distally
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.