Download 牙列拥挤的治疗 Treatment of Crowed Teeth 西安交通大学口腔医学院

牙列拥挤的治疗
Treatment of Crowed Teeth
西安交通大学口腔医学院
口腔正畸教研室
Definition
• Teeth in the dental arch (or arch jaw)
on the location or lack of space, the
rules can not be arranged in a normal
arch, and showed the phenomenon
of overlapping dislocation.
Crowding is a deformity in one of
the most common manifestations。It
can be separate, but the majority of
malformations are in conjunction with
other deformities.
1 pathogen of crowding
Mechanism ：
1
Teeth is greater than the volume of
bone mass (relative and absolute)
• Teeth greater normal greater
• Bone
normal
smaller smaller
Heredity factors
Evolution factors
Mandibular hypoplasia
Tooth number, size, shape
Environmental factors
Obstacles of teeth eruption
Early loss of deciduous teeth,
Molars forward
Retention of deciduous teeth
Eruption of permanent teeth dislocation
Oral bad habits
2 Performance
• Simply crowding is little effect
opposite type
Impact on the dental arch
3 Degree of crowding
According to the level :
By model measurement

Mild < 5.0mm

Moderately > 5.0mm
< 8.0mm

Severe > 8.0mm
By location :
Anterior
Middle
Posterior
General treatment of dentofacial
deformities
• Treatment principles
1. Correction standard :individual
normal occlusion
2. Treatment according to the
mechanism of malformation
3. Remove the causing
• Treatment principles
4. In line with the growth and
development of the law
5. In line with the patients own body's
physiological characteristics
6. Appliance design should be simple
and practical
The key to the treatment of crowding
is gaining space.
How to effectively meet the individual
physiological characteristics and
keep stable of gained space is the
basis for successful treatment.
4 The method of gaining space
1 expansion of the dental arch
width
1. orthopaedic expansion
Branch-type base frame and two forms. To open
the palate raphe extended mainly to expand
0.5mm/ day, the cheek teeth to tilt less mobile.
Adults need assisted rapid palatal expansion for
zygomatic alveolar ridge cortical incision,
reducing the resistance to expansion.
Haas-type
Hyrax expander
slow palatal expansion
rapid palatal expansion
pre
after
Dental arch expansion ：

1.0mm of Palatal expansion can get
0.7mm space

relapse rate:
10% - 30%
2. Orthodontic expansion
Dental arch expansion
Appliance-use activities in the spring or split
spring fixed to the expansion of the
expansion. Mainly to the buccal tooth
inclination mobile. The general availability of
gap 2.0 - 3.0mm. The application of the
tongue by the teeth of the arch to the tilt
caused by stenosis.
Removable appliance
Quad helix
2. functional expansion
FH
2 Molar distalization：
1.Acrylic cervical occipital appliance
(ACCO)
 Removable
Face
lip
bow
bumper
appliance
Acrylic cervical occipital
appliance
(ACCO)

Each side can get 4.0mm.
As
to rely on the activities of the
mobile appliance on the crown
And
face-bow to the root of the
combined mobile.
Face-bow
to the root is the key to
mobile-line traction to the teeth against
the center is located at the top, traction
generally about 150g, traction time was
10 - 12 hours one day. Force of Oral
appliance on the crown is about 30 g,
required to wear all day.
lip bumper ：
The
main role is to use the force of lip
vertical mandibular molar (Upright) and
molar re-gap (due to early loss of deciduous
teeth); to stop the forces of muscular buccal
premolar arch area to expand.
• 3 Reducing circumference treatment ：
（1）. Indications
• Adult patients;
For the bell-shaped central incisors;
Mild anterior crowding;
People with little or no dental caries
（2) treatment
Reduce the diameter of the teeth
0.5mm on each side can be reduced
Attention to the restoration of the original
contact point
Restoration of surface finish
Not suitable for patients with a higher rate of
caries
• (3) procedures
Aligned teeth to normal relations.
Determine the number, and the order is
from back to front.
Separate the contact points.
Fine curved nose drilling, fluoride.
4 Extraction :
The factors of extraction to consider:
The space requirements of Correction
The adjustment of the dental arch midline
Crowding of the site
The
principle of extraction
The first premolar is the first choice
Generally, incisors and canines do not
consider to extract
Teeth
extracted should be closed to the
crowding site
Permanent
teeth germ should be
chceked in Mixed dentition extraction
Symmetry extraction
5 The principle of correction of
crowding

Mild crowding: Mild crowding can be
treated by expanding the arch or molar
distalization. In the mixed dentition, the leeway
space can be used to disarm the crowded
dentition.

Moderately crowded: Non-extraction
treatment should be possibly considered in
the growing season, like molar distalization.
The direction of the face-bow is according to
mandibular plane angle and height of 1 / 3
surface
Moderate
crowding: Extraction
orthodontic treatment may be considered
in the non-growth season. The space
obtained by extraction is mainly used to
ease the crowded dentition, and the
remaining space will enable the posterior
teeth to move to mesial. Anchorage
control should also be paid attention in
the treatment of moderately crowding,
especially in maxillary.

Severe crowding: Extraction treatment
should be considered in growing and non-
growing season in general. The space
obtained by extraction is used to lifting the
crowding. Anchorage control is the critical
point in severe crowding treatment. Loss of
anchorage will lead the failure of treatment.
 Anchorage controlled manner:
1. Against the tooth movement by the
bending such as tip-back bending .
2. Reducing the friction： such as the single point
ligation
3. To increase the number of anchorage teeth： 7
band .
4. Using the opposite jaw to provide anchorage;
using II, III type traction.
5. Extraoral anchorage; Top, Pillow, neck.
6. Implant Anchorage
小结
crowding
teeth greater
bone smaller
Reducing tooth
volume
Extraction
Reducing diameter
Increasing bone
mass
Expand
Distraction
osteogenesis
Comprehensive space analysis
1 severity of crowding
2 protrusion of anteriors
3 curve of spee
4 mesial drift of anchorage molar
5 maxillofacial skeletal patterns
6 facial profile
7 growth status