牙列拥挤的治疗牙列拥挤的治疗Treatment of Crowed TeethTreatment of Crowed Teeth

西安交通大学口腔医学院西安交通大学口腔医学院口腔正畸教研室口腔正畸教研室

DefinitionDefinition

• 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 t

he most common manifestations 。 It

can be separate, but the majority of m

alformations are in conjunction with ot

her deformities.

11 pathogenpathogen of crowding of crowding

Mechanism ：1 Teeth is greater than the volume of bo

ne 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 2 PerformancePerformance

• Simply crowding is little effect opposite type Impact on the dental arch

3 Degree of crowding3 Degree of crowding

MildMild < 5.0mm< 5.0mm ModeratelyModerately > 5.0mm> 5.0mm

< 8.0mm < 8.0mm SevereSevere > 8.0mm> 8.0mm

According to the level :According to the level :

By model measurementBy model measurement

AnteriorMiddle Middle Posterior

By locationBy location ::

General treatmentGeneral treatment of of dentofacial dentofacial deformitiesdeformities

• 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 space4 The method of gaining space

1. orthopaedic expansion1. orthopaedic expansion Branch-type base frame and two forms. To open thBranch-type base frame and two forms. To open th

e palate raphe extended mainly to expand 0.5mm/e palate raphe extended mainly to expand 0.5mm/ day, the cheek teeth to tilt less mobile. Adults needay, the cheek teeth to tilt less mobile. Adults need assisted rapid palatal expansion for zygomatic ald assisted rapid palatal expansion for zygomatic alveolar ridge cortical incision, reducing the resistanveolar ridge cortical incision, reducing the resistance to expansion.ce to expansion.

1 expansion of the dental arch 1 expansion of the dental arch widthwidth

Haas-type Haas-type

Hyrax expanderHyrax expander

slow palatal expansionslow palatal expansion

rapid palatal expansionrapid palatal expansion

pre after

1.0mm1.0mm of Palatal expansion can get Palatal expansion can get 0.7mm space0.7mm space

relapse rate: relapse rate:      10% - 30%     10% - 30%

Dental arch expansionDental arch expansion ：：

2. Orthodontic expansion2. Orthodontic expansion

Dental arch expansion Dental arch expansion Appliance-use activities in the spring or split Appliance-use activities in the spring or split spring fixed to the expansion of the expansiospring fixed to the expansion of the expansion. Mainly to the buccal tooth inclination mobin. Mainly to the buccal tooth inclination mobile. The general availability of gap 2.0 - 3.0mmle. The general availability of gap 2.0 - 3.0mm. The application of the tongue by the teeth of . The application of the tongue by the teeth of the arch to the tilt caused by stenosis.the arch to the tilt caused by stenosis.

Quad helix

Removable appliance

2. functional expansion2. functional expansion

FHFH

2 Molar distal2 Molar distalization ：：1.Acrylic cervical occipital appliance (ACCO)

Removable applianceRemovable applianceFace bowFace bowlip bumperlip bumper

Acrylic cervical occipital appliance (ACCO)

Each side can get 4.0mm.Each side can get 4.0mm.

As to rely on the activities of the moAs to rely on the activities of the mo

bile appliance on the crownbile appliance on the crown

And face-bow to the root of the comAnd face-bow to the root of the com

bined mobile.bined mobile.

Face-bow to the root is the key to mobiFace-bow to the root is the key to mobi

le-line traction to the teeth against the cle-line traction to the teeth against the c

enter is located at the top, traction geneenter is located at the top, traction gene

rally about 150g, traction time was 10 - rally about 150g, traction time was 10 -

12 hours one day. Force12 hours one day. Force of Oral applianOral applian

ce on the crown is about 30 g, required ce on the crown is about 30 g, required

to wear all day.to wear all day.

lip bumperlip bumper ：：The main role is to use the force of lip verticThe main role is to use the force of lip vertic

al mandibular molar (Upright) and molar re-gal mandibular molar (Upright) and molar re-g

ap (due to early loss of deciduous teeth); to ap (due to early loss of deciduous teeth); to

stop the forces of muscular buccal premolar stop the forces of muscular buccal premolar

arch area to expand.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 Extraction4 Extraction : : The factors of extraction to consider: The factors of extraction to consider: The space requirements of CorrectionThe space requirements of Correction

The adjustment of the dental arch midline The adjustment of the dental arch midline Crowding of the siteCrowding of the site

The principle of extraction The principle of extraction

The first premolar is the first choice GenThe first premolar is the first choice Gen

erally, incisors and canines do not considerally, incisors and canines do not consid

er to extracter to extract

Teeth extractTeeth extracted should be closed to the should be closed to the

crowding sitecrowding site

Permanent teethPermanent teeth germ should be chgerm should be ch

ceked in Mixed dentitionceked in Mixed dentition extraction extraction

Symmetry extractionSymmetry extraction

5 The principle of5 The principle of correction of crowdicorrection of crowdingng

Mild crowding: Mild crowding can be treateMild crowding: Mild crowding can be treate

d by expanding the arch or molar distalization. Id by expanding the arch or molar distalization. I

n the mixed dentition, the leeway space can be n the mixed dentition, the leeway space can be

used to disarm the crowded dentition.used to disarm the crowded dentition.

Moderately crowded: Non-extraction treatModerately crowded: Non-extraction treat

mentment should be possibly considered in the gshould be possibly considered in the g

rowing season, like molar distalization. The drowing season, like molar distalization. The d

irectionirection of the face-bow is according to mandface-bow is according to mand

ibular plane angle and height of 1 / 3ibular plane angle and height of 1 / 3 surfacesurface

Moderate crowding: Extraction orthodonModerate crowding: Extraction orthodon

tic treatment may be considered in thetic treatment may be considered in the no

n-growth season. The space obtained by growth season. The space obtained by

extraction is mainly used to ease the croextraction is mainly used to ease the cro

wded dentition, and the remaining space wded dentition, and the remaining space

will enable the posterior teeth to move to will enable the posterior teeth to move to

mesial. Anchorage controlmesial. Anchorage control should also be should also be

paid attention in the treatment of moderatpaid attention in the treatment of moderat

ely crowding, especially in maxillary.ely crowding, especially in maxillary.

Severe crowding: Extraction treatment shSevere crowding: Extraction treatment sh

ould be considered in growing and non-groould be considered in growing and non-gro

wing season in general.wing season in general. The spaceThe space obtaineobtaine

d by extraction is used to lifting the crowdid by extraction is used to lifting the crowdi

ng. Anchorage controlng. Anchorage control is the criticalis the critical point in

severe crowding treatment. Loss of anchorsevere crowding treatment. Loss of anchor

age will lead the failure of treatment.age will lead the failure of treatment.

Anchorage controlled manner: Anchorage controlled manner:

        1. Against the tooth movement by the bendi  1. Against the tooth movement by the bendi

ng such as tip-back bending . ng such as tip-back bending .

     2. Reducing the friction     2. Reducing the friction ： ： such as the single point such as the single point

ligation ligation

     3. To increase the number of anchorage teeth     3. To increase the number of anchorage teeth ： ： 7 7

band . band .

     4. Using the opposite jaw to provide anchorage; us     4. Using the opposite jaw to provide anchorage; us

ing II, III type traction. ing II, III type traction.

     5. Extraoral anchorage; Top, Pillow, neck.      5. Extraoral anchorage; Top, Pillow, neck.

     6. Implant Anchorage     6. Implant Anchorage

小结小结 crowding

teeth greater bone smaller

Reducing tooth Increasing bone volume mass

Extraction Expand Reducing diameter Distraction

osteogenesis

Comprehensive space analysisComprehensive 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