Mandibular Retroguathism Question And Answers

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Miscellaneous Short Essays

Mandibular Retroguathism

Question 1. Mandibular retroguathism.
Answer.

  • Refers to more backward placement of jaw.

Features of retrognathism:

  • Facial profile – convex
  • Facial divergence – Posterior divergent
  • Anteroposterior relation – Class 2
  • Mento labial sulcus – Deep
  • Hyperactive mentalis activity
  • Reduced nasolabial angle

Treatment of retrognathism:

  • In growing patients – Myofunctional therapy Ex. Activator, FR2
  • In non-growing patients
    • Orthodontic camouflage – Extraction of 1st premolars
    • Mandibular advancement

Read And Learn More: Orthodontics Short And Long Essay Question And Answers

Question 2. Causes of Canine impaction.
Answer.

Orthodontics Miscellaneous Causes of Canine impaction

Question 3. Mechanism of Bone Growth.
Answer.

Bone Deposition and resorption

  • Together with bone deposition and resorption is called bone remodeling

Effects of bone deposition and resorption:

  • Change in size
  • Change in shape
  • Change in proportion
  • Change in bone relationship with adjacent structures

Cortical Drift

  • Movement of bone occurs towards bone deposition called cortical drift
  • If bone deposition and resorption are equal
  • Thickness of bone remains, constant
  • If bone deposition is more than resorption
  • The thickness of bone is more toward the deposition

Displacement

  • Movement of whole bone as a unit

Primary displacement:

  • Displacement of bone as a result of its own growth

Secondary displacement:

  • Displacement of bone as a result of growth of adjacent bone

Question 4. Causes of Root resorption.
Answer.

Orthodontics Miscellaneous Causes of root resorption

Question 5. Envelope of Discrepancy.
Answer.

  • It helps in treatment planning
  • The choice of treatment depends on the movement of the teeth required
  • By orthodontic (fixed mechanotherapy) the tooth can be moved only at a specific distance
  • If the movement of teeth beyond this limit is required, orthopedic/functional appliances can be used
  • Beyond this limit, the treatment of choice is orthognathic surgery

Orthodontics Miscellaneous Fixed Mechanotheraphy

Question 6. Self-correcting Anomalies/Transient Malocclusions.
Answer.

Orthodontics Miscellaneous Anomalies

Miscellaneous Short Questions And Answers

Question 1. Apertognathia.
Answer.

It is a condition in which there is space between upper and lower teeth when some teeth are in contact at one/more points

Orthodontics Miscellaneous Apertognathia

Question 2. Growth site and Growth center.
Answer.

Growth site:

  • These are growth fields that have a special significance in the growth of a particular bone
  • Posses intrinsic growing potential
    Example. Condyle, maxillary tuberosity

Growth Centres:

  • These are growth sites that control the overall growth of bone
  • Have growth potential
    Example. Epiphyseal plates of long bones

Question 3. Cranial Base Flexure.
Answer.

  • During the embryonic phase, the cranial base is flexed between the pituitary fossa and sphenoccipital junction
  • It is accompanied by developing brain stem

Cranial Base Flexure Results

  • Downward placement of foramen magnum
  • Aids in increased neurocranial capacity
  • Downward displacement of the face
    Age: 10th week of IU life, Angle – 65th

Question 4. Carpal Index.
Answer.

  • One of the skeletal maturity indicator
  • Used as a part of hand wrist
  • Carpals – consist of eight small bones arranged in

Proximal Row

  • Scaphoid
  • Triquetral
  • Lunate
  • Pisiform

Distal row

  • Trapezium
  • Trapezoid
  • capitate
  • Humate
  • These bones show specific patterns of appearance, ossification, and union
  • These are compared with standards

Orthodontics Miscellaneous Anatomy of hand wrist

Question 5. Torquing Auxillaries.
Answer.

Torquing Auxillarie Springs:

  • Made of stainless steel /Ni – titanium
  • Force exerted is directly proportional to the diameter and modulus of elasticity of the material of the wire
  • Stainless steel exerts greater force

Question 6. Sterilization in Orthodontics.
Answer.

Definition: Defined as the destruction of all life forms

Types of Instruments:

  • Critical – Penetrate the mucosa
  • Semi-critical – Touches mucosa but does not penetrate
  • Least critical – Surfaces touched during treatment

Instruments Requiring Sterilization:

  • Mirrors
  • Explorers
  • Banding and bonding instruments
  • Bands
  • Pillers
  • Ligature directors

Question 7. Growth Trends.
Answer.

By overlapping consequent cephalograms Tweed, designed a pattern of growth called “Growth trends”

Groups

Type A

  • Simultaneous growth of maxilla and mandible
  • 25% of case
  • ANB angle unchanged

Type A subdivision

  • Protruding maxilla
  • ANB angle increased

Type B

  • Increase in maxillary growth

Type B subdivision

  • ANB angle large
  • Unfavorable

Type C

  • Increased growth of the mandible
  • Decreased ANB angle

Type C Subdivision

  • Mandibular incisors touches lingual surfaces of maxillary incisors

Question 8. Growth Curve.
Answer.

  • Indicates the degree of difference between two growing individuals in all four planes including the time factor
  • As everyone does not have the same growth pattern, deviation from normal growth pattern cannot be diagnosed
  • Thus the growth of such individuals is compared with a standard growth chart

Question 9. Fontanelles.
Answer.

  • They bridge the gap between bones that limit them.
  • Made up of durameter, primitive periosteum and aponeurosis

Orthodontics Miscellaneous Fontanelles

Frontanelles Importance:

  • Indicates brain development
  • A depressed level indicates dehydration
  • Increased level indicates increased intracranial pressure

Orthodontics Miscellaneous Fontanelles and sutures in neonatal skull

Question 10. Safety valve mechanism.
Answer.

  • Increase in inter-canine width is one of the important factor in overcoming incisal liability
  • At the age of 12, maxillary anterior prolines such that inter-canine width increase

Significance of safety value mechanism:

  • This increase in maxillary inter canine width hinders the forward growth of the mandible
  • This increase in width behaves like it holds the forwardly growing mandible

Question 11. Curve of Spee.
Answer.

  • It is antero-posterior curve of occlusion
  • It begins from the tip of lower canine to the cusp tips of bicuspids and molars upto the condyle

Significance of curve of Spee:

  • Normal value – 1.5 – 2mm
  • If the curve is extended, it forms a circle of about 4 diameter
  • It represent the axial alignment of lower teeth
  • It requires a gradual progressive increased mesial tilting of teeth towards the molar

Question 12. Anterior bite plane and its mode of action.
Answer.

Uses of anterior bite plane: For treatment of deep bite

Mode of action:

  • Consist of the flat ledge of acrylic behind the upper anterior
  • When the patient bites the mandibular incisors contact the bite plane, thus dis occlude the posterior due to which they are free to erupt

Components of anterior bite plane:

  • Adam’s clasp on molar – As a retainer
  • Labial bow – Counter any forward component of force on upper anterior

Question 13. Orbital law of canine.
Answer.

  • It is used in Simon’s classification
  • Orbital plane perpendicular to Frankfort horizontal plane is used
  • This plane is dropped down from the bony orbital margin directly under the pupil of the eye
  • According to Simon, this plane should pass through the distal third of the upper canine
  • This is known as “Simon’s law of canine “or” Orbital law of canine”

Orbital law of canine significance:

  • It is used to describe malocclusion in a sagittal plane
  • When the dental arch is farther from the orbital plane it is called protraction
  • When the dental arch is closer then it is called retraction

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