Transcript Terms in Orthodontics

Terms Terms
in Orthodontics
in Orthodontics
Dr.Omar S.M.J.Ali
PhD Orthodontic
• Over jet :
• Overbite
• Open bite:
• Deep bite:
• Cross bite
• Scissor bite
• Prognathism:
• Retrognathism:
• Midline shifting
• Diastema
• Inclination
• Torque:
a torsion force applied to a tooth to produce or
maintain crown or root movement
Introduction
Orthodontic tooth movements are based
on the ability of bone to react to
mechanical stresses with the apposition
and resorption of alveolar bone.
What is needed !!!
1- Tooth
2- Health PDL
A- Fibers transmitted force
applied to the tooth.
B- Damping.
C- Cells within PDL.
3- Bone
4- Applied Force
Mechanical Principles in Orthodontic
1-Center of Resistance: A-point at which resistance
to the movement can be concentrated for
mathematical analysis.
Location of Cres:
The Roots
Attachment
Root morphology
alveolar bone
height
Cres
Number of Roots
Root length
Center of Rotation:
The point around which rotation actually occurs when
an object is being to move.
Types Of Tooth Movement
1. Extrusion:
A translational type of tooth movement
parallel to the long axis of the tooth in the
direction of the occlusal plane.
Occlusal plane
2. Intrusion:
A translational type of tooth movement
parallel to the long axis of the tooth in the
direction of the apical level.
Apical Level
3. Pure Root Movement:
The type of tooth movement for which the
center of rotation is at the incisal edge.
Center of Rotation
Incisal edge
4. Controlled Tipping:
A type of tooth movement consisting of
rotation about the apex of the tooth.
Apex
Center of Rotation
5. Uncontrolled Tipping:
Movement of the crown and the apex of the
tooth in opposite direction.
Apex
Center of Rotation
Occlusal Plane
6. Translation (Bodily movement):
All points on a tooth move in the same
direction by the same amount.
Apex
Occlusal Plane
7.
Rotation Movement:
Movement of the tooth around its long axis by
two forces equal in magnitude and opposite in
direction.
Force 1
LONG AXIS
Force 2
Occlusal View
Uncontrolled
Tipping
Bodily
CRot=
Cres=
Controlled
Tipping
Pure root
Movement
Intrusion
Extrusion
When to Use—What Appliance !!
Bodily
Intrusion
Tipping
Fixed
Rotation
Extrusion
When to Use—What Appliance !!
Bodily
Intrusion
Tipping
Removable
Rotation
Extrusion
Optimal orthodontic force:
The lightest
that will move
the(gm)
tooth to a
Type offorce
Movement
Force
desirable
position in shortest35-60
possible time with no
Tipping
iatrogenic effect.
Bodily Movement
(Translation)
70-120
Root
uprighting
50-100
Rotation
35-60
Extrusion
35-60
Intrusion
10-20
Force Measurement
Classification of Force by the Rate of
Decay
1.Continuous---Force maintained at the same
appreciable fraction of the original from one patient visit to
the next.
2.Interrupted---Force levels decline to zero
between activations.
Both 1 & 2 forces can be produced by fixed appliances
that are constantly present.
3.Intermittent---Force level decline to zero
intermittent,(e.g. when the removable appliance is taken out,
only to resume when the appliance is reinserted into mouth.
These forces also decay as tooth movement occurs.
The Criteria of Ideal Delivery Force
1. Provide optimal tooth-moving forces that elicit the
desired effects.
2. Be comfortable and hygienic for the patient.
3. Require minimal operator manipulation and chairtime.
4. Require minimal patient co-operation.
5. Be economical.
Factors Affecting Rate of Tooth
Movement
1-The Force Applied
2- Age
3- Individual Variations
4-Tooth
a- The surface area of the
roots.
b- The types of tooth movement
c- Other factors such as
intercuspation of the teeth
Orthodontics Adverse Affects
1- Pulp
*Transient Inflammatory
Response.
*Loss of Vitality.
2-Root
3- PDL
4-Bone
Orthodontics Adverse Affects
1- Pulp
2-Root
Root Resorption.
At Risk: a-Distorted apices
3- PDL
4-Bone
b-Thin Roots
(1-2) mm Root Length
Computer and Tooth Movement
3-D dental models are used to
stimulate 3-D movement of teeth
including rotations, and tipping
during orthodontic treatment. The
proposing techniques are a part of
the development diagnosis system
designed to replace manual
measurement method.
The initial result showed that
maximum stresses are produced on
the outside layers. It had also shown
that during tipping movement, the
greater stresses occurred at alveolar
crest and not at apex. Rotational
forces in general produced the least
stresses at all point on root surface.
Dentin
Cementum