Practice Test

📝 Explanation:

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.

📝 Explanation:

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.

📝 Explanation:

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.