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The Etiology of Orthodontic Problems

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Christine Chny

on 18 March 2014

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Transcript of The Etiology of Orthodontic Problems

The Etiology of Orthodontic Problems
Equilibrium Theory and Development of the Dental Occlusion
Functional Influences on Dentofacial Development
Etiology in Contemporary Perspective
Equilibrium theory
states that an object subjected to unequal forces will be accelerated and thereby will move to different position in space
Equilibrium Effects on the Dentition
The duration of a force is more important than its magnitude.
Equilibrium Effects on Jaw Size and Shape
If a function is lost or changed, the functional processes of bones and muscles will likewise be altered.
Function and Dental Arch Size
Enlargement of the mandibular gonial angles due to hypertrophy of the mandibular elevator muscles
Biting Force and Eruption
According to clinical studies:
Sucking and Other Habits
Combination of direct pressure on the teeth and an alteration in the pattern of resting cheek and lip pressures
Tongue Thrusting
"tongue thrust swallowing"
Respiratory Pattern
Respiratory needs are the primary determinant of the posture of the jaws and tongue.
Etiology of Crowding and Malalignment
Appear to arise from an interaction between the initial position of the tooth buds and the pressure environment that guides eruption of the teeth.
Etiology of Skeletal Problems
Skeletal orthodontic problems, resulting from malpositions or malformations of the jaws arise from:
inherited patterns
defects in embryologic development
functional influences
Environmental Influences
Christine Joy S. Chny, DMD
If a tooth is subjected to a continuous force from an orthodontic appliance, it does move.
The force applied by the orthodontist has altered the previous equilibrium, resulting in tooth movement.
Masticatory forces
Pressure from lips, cheeks and tongue
Pressures from external forces (habits and orthodontic appliances)
Periodontal fiber system (transseptal fibers of the gingiva)
Pressure from soft tissues
If an injury to the soft tissue of the lip results in scarring and contracture, the incisors in the vicinity will be moved lingually as the lip tightens against them
Pressures from Soft Tissue
On the other hand, if restraining pressure by the lip or cheek is removed, the teeth move outward in response to unopposed pressure from the tongue.
The location of the muscle attachments is more important in determining bone shape than mechanical loading or degree of activity
Muscle growth can produce a change in shape of the jaw, particularly at the coronoid process and angle of the mandible
There are no differences in maximum biting force between children with long faces and normal faces, nor between either group of children and long-face adults.
It seems more likely that the different biting force is an effect rather than a cause of malocclusion
Malocclusion characterized by:
flared and spaced maxillary incisors
lingually positioned lower incisors
anterior open bite
narrow upper arch
placement of the tongue tip forward between the incisors during swallowing
2 circumstances:
younger children in transitional stage representing normal physiologic maturation
in individuals of any age with displaced incisors, compensating for the space between the teeth
Therefore it seems entirely reasonable that an altered respiratory pattern, such as breathing through the mouth rather than the nose, could change the posture of the head, jaw, and tongue.
Adenoid facies
Respiratory Pattern
The classic “adenoid facies,” characterized by narrow width
dimensions, protruding teeth, and lips separated at rest, has often been attributed to mouth breathing.
The conclusion is, therefore, that minor Class 1 problems often are caused primarily by alterations in function.
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