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 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.
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.
Which of the following shows 200 % of its adult growth by age 9-10 years
1) Lymphoid
2) General
3) Genital
4) Neural
Orthodontics
Answer: 1
The lymphoid system, which includes lymph nodes, spleen, and other lymphatic tissues, undergoes significant growth during childhood. By the age of 9-10 years, the lymphoid tissue can reach approximately 200% of its adult size due to the increased demand for immune function during this period. This growth is part of the body's preparation for increased exposure to pathogens as children interact more with their environment.
Flaccid lip, digit sucking, high frenum attachment & poor muscle tone are the etiology of :
1) Anterior cross bite
2) Diastema
3) Anterior bite
4) Posterior cross bite
Orthodontics Answer: 2
Midline diastema Etiology
Normal developing dentition - (Ugly Ducking Stage)
Parafunctional habits
- Flaccid lips along with poor muscle tone
- Simple Tongue thrust can cause anterior open bite as well as diastema
- Thumb sucking or digit sucking for a prolonged time period
Retrognathic mandible/ Prognathic mandible
Frenum attachments
Mesio-distal angulation of teeth
Tooth anomalies (eg. supernumerary teeth, peg laterals, absence of laterals)
Pathological (Juvenile periodontitis)
The part of the removable appliance which provides the anchorage is
1) Adams clasp
2) Base plate
3) Active labial bow
4) Guided springs
Orthodontics Answer: 2
SOLUTION
Baseplate: The hard plastic part of some retainers that covers the gum and has the wire components of the retainers attached to it.
Supracrestal fibrotomy is done after correction of:
1) Crowding
2) Proclined incisors
3) Severely rotated teeth
4) Space closure
Orthodontics Answer: 3
Solution
Circumferential supracrestal fibrotomy (CSF) eliminates the pull of the stretched supracrestal gingival fibres which are the major cause of orthodontic relapse.