MDS PREP
Following orthodontic treatment of rotated tooth, relapse is most commonly due to
1) Oblique fibers
2) Supracrestal fibers
3) Sharpey’s fibers
4) Apical fibers
Orthodontics Answer: 2
Solution
This is because elastic supracrestal fibres remodel extremely slowly and can still exert forces capable of displacing a tooth even at 1 year after removal of an orthodontic appliance.
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.
Analysis which is similar to Pont’s analysis is_______?
1) Linder Harth index
2) Korkhaus analysis
3) Bolton’s analysis
4) (A) and (B)
Orthodontics Answer: 4
SOLUTION
· Pont’s in 1905 presented a system whereby the measurement of the four maxillary incisors automatically established the width of the arch in the premolar and molar region. If measured value is less than calculated value, it indicates the need for expansion.
· Linder Harth index: This analysis is very similar to Pont’s analysis except that a new formula has been proposed to determine the calculated premolar and molar value.
· Korkhaus analysis: This analysis is also very similar to Pont’s analysis it makes use of Linder Harth’s formula to determine the ideal arch width in the premolar and molar region.
In addition this analysis utilizes a measurement made from the midpoint of the inter-premolar line to a point in between the two maxillary incisors.
· Bolton’s analysis: The Bolton’s analysis helps in determining disproportion in size between maxillary and mandibular teeth.
Orthodontic tooth movement is inhibited by which of the following drugs
1) NSAIDS, such as Brufen
2) OPIOIDS, such as CORTISONE
3) Antibiotics such as tetracycline
4) Vasoconstrictors such as adrenaline
Orthodontics Answer: 1
SOLUTION
NSAIDS, i.e. Brufen, etc. inhibit tooth movement as they interfere with production of prostaglandins.
• Nimesulide does not interfere with PG production and so can be safely given during tooth movements.
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
Supervision of child"s dentition is critical at or in
1) 3-6 years primary dentition
2) 7-10 years mixed dentition
3) 11-14 years permanent dentition
4) 14-17 years post permanent
Orthodontics
Answer: 2
Supervision of a child's dentition is critical during all developmental stages, but the 7-10 years age range, which is the mixed dentition stage, is a particularly important time for monitoring. This is because it is the period when both primary (baby) and permanent (adult) teeth are present in the mouth. During this stage, children are at risk for various dental problems such as crowding, malocclusion, and the loss of primary teeth that can affect the eruption of permanent teeth.
A child is 7-year-old skeletal class I relation. He has the habit of thumb sucking. There is slight overjet and anterior spacing. If he discontinue the habit
1) Overjet will reduced
2) Overjet increases as permanent canines erupt
3) Lower incisors incline labially
4) Result in crowding of anterior teeth
Orthodontics
Answer: 1
In a child with a skeletal Class I relationship and slight overjet, thumb sucking can contribute to the maintenance of the overjet due to the anterior teeth being pushed forward by the thumb. If the child discontinues thumb sucking, the anterior teeth may naturally reposition themselves, leading to a reduction in overjet.
Option 2 is incorrect because while the eruption of permanent canines can influence the occlusion.
Option 3 is also incorrect; the lower incisors would not necessarily incline labially if the thumb sucking habit is stopped.
According to Angle, the key to normal occlusion in adults is the anteroposterior relationship. His description of teeth relationships in normal occlusion remains a fundamental observation. Angles observations are based on which teeth that are most reliable to understand occlusion
1) First molars and canines
2) First molars and first Premolars
3) Canines and first Premolars
4) First molars and central incisors
Orthodontics Answer: 1
SOLUTION
The mesial incline of the upper canine occludes with the distal incline of the lower [canine];
the distal incline of the upper canine occludes with the mesial incline of the buccal cusp of the lower first premolar.