NEET MDS Shorts
831683
OrthodonticsSOLUTION
Simon used the orbital plane (a plane perpendicular to the F-H plane at the margin of the bony orbit directly under the pupil of the eye).
According to Simon, in normal arch relationship, the orbital plane passes through the distal axial aspect of the maxillary canine
Malocclusions described as anteropostenor deviations based on their distance from the orbital plane are as follows:
1. Protraction: The teeth, one or both, dental arches, andYor jaws are too far forward, i.e. placed forward or anterior to the plane as compared to the normal where the plane passes through the distal incline of the canine.
2. Retraction: The teeth, one or both dental arches and/or jaws are too far backward, i.e. placed posterior to the plane than normal
646168
OrthodonticsSOLUTION
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.
377077
OrthodonticsEtiology 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.
170190
Orthodonticswe are applying force distally only..force vector will rotate the tooth distally
810544
OrthodonticsCrowding 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.
940957
OrthodonticsSolution
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.
851345
OrthodonticsSOLUTION
Light and continuous
Use of continuous light force is recommended to be applied for adult group of patient rather than intermittent force as applied by removable appliance. This is because continuous forces are expected to bring about direct resorption of the root socket. They should hence not occlude more than a small percentage of blood vessels with in the periodontal ligament, not substantially interfere with their nutritional supply and little interference
with normal biologic functioning. In adult due to heavy force teeth may devitalize because the opening into the tooth (apical foramen) is smaller and blood vessels can be easily disrupted.
222530
OrthodonticsIn 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.