Hospital of Stomatology,Xi’an Jiaotong University
Department of Orthodontics
Professor ZhouHong

Orthodontics is a branch of Clinical Stomatology , the mechanisms of major research and development of dentofacial deformities, diagnosis, prevention and treatment.
Ortho dontics Dentofacial Orthopedics
Mal occlusion Dentofacial Deformity

 The area and specialty of dentistry concerned with the supervision, guidance and correction of the growing or mature dentofacial structures, including those conditions that require movement of teeth or correction of malrelationships and malformations of their related structures and the adjustment of relationships between and among teeth and facial bones by the application of forces and/or the stimulation and redirection of functional forces within the craniofacial complex.

 Major responsibilities of orthodontic practice include the diagnosis, prevention, interception and treatment of all forms of malocclusion of the teeth and associated alterations of their surrounding structures; the design, application and control of functional and corrective appliances; and the guidance of the dentition and its supporting structures to attain and maintain optimal occlusal relations, physiologic function and esthetic harmony of facial and cranial structures.

 A malformation of the teeth , jaws and/or face characterized by disharmonies of size , form and/or function . The term encompasses problems such as malocclusion , cleft lip and palate and other skeletal or soft tissue anomalies , or syndromes that involve the face and the dentoalveolar complex.

一、 The manifestation of Dentofacial
Deformity
1 malposition of individual, abnormity of arch form ,tooth malalignment
2 maxillomandibular malrelationship
3 malrelationship between jaw and cranium

（ Microdontia ）
（
Anterior crossbite
）
（
Spaces
） （
Suprenumerary tooth
）

（ Congenital missing tooth ）
（
Ectopic eruption
）

Bimaxillary Dentoalveolar Protrusion and Crowding

（
Deep Overbite and Overjet
）

Deep overjet 11.0 mm
Deep overbite 90
%

（ Deep Overbite with Crowding ）

Mandibular prognathism

Maxillar Retrusion with Mandibular Protrusion

Maxillary retrognathism
Narrow of upper arch
Mandibular prognathism

（ Edge-to-edge bite ）

Crowding with edge-to edge bite

Bimaxillary dentoalveolar protrusion

(Lateral view )
(frontal view)

Open bite

(Lateral view )
(frontal view)

Mandibular Shift

(Lateral view )
(frontal view)

Introversion deep overbite

二、 epidemiology prevalence rare ： 60`s: 29.33% - 48.87%



2000`s: 51.84 – 72.92%
Individual Normal Occlusion
Ideal Normal Occlusion
Incisor Irregularity Index

A+B+C+D+E= Anterior lower incisor crowding
0-1 ideal
2-3 mild crowding
4-6 moderate crowding
7-10 severe crowding
> 10 extreme crowding

三、
1 psychosocial influences
2 oral function
3 relation to dental disease
4 Aesthetic impact

Relation between size of overjet and prevalence of traumatised anterior teeth
Overjet (mm) Incidence %
5 22
9 24
>9 44

Dr Sarver:
Malocclusion of teeth is not disease , rather, it is a disability with a potential influence on physical and mental health.
Orthodontics
— current principles and techniques
2000 By Graber

1. To improve dentofacial appearance.
2. To correct the occlusal function of the teeth
3. To eliminate occlusion that could damage the long-term health of the teeth and periodontium

四、
1 、
Crowed,irregular and protruding teeth have been a problem for some individuals since antiquity,and attempts to correct this disorder go back at least to 1000 BC.primitive orthodontic appliance have been found in both Greek and Etruscan matrials.

1850 the first texts that systematically described orthodontics appeared,the most notable being Norman
Kingsley’s Oral
Deformities.Kingsley who had a tremendous influence on
American dentistry in the latter half of the nineteeth century,was among the first to use extroral force to correct protruding teeth.He was also a pioneer in the treatment of celft palate and related problems.

Their emphasis in orthodontics remaind the alignment of the teeth and the correction of facial proportions. Little attention was paid to the dental occlusion.In an era when an intact dentition was a rarity,the details of occlusal relationships were considered unimportant.

Edward H Angle can be credited with much of the development of a concept of occlusion in the natural dentition.His increasing interest in dental occlusion and in the treatment necessary to obtain normal occlusion led directly to his development of orthodontis as a specialty,with himself as the “father of modern orthodontics.”

The publication of Angle’s classification of malocclusion in the 1890s was an important step in the development of orthodontics because it not only subdivided major types of malocclusion but also included the first clear and simple definition of normal occlusion in the natural dentition.If this molar relationship existed and the teeth were arranged on a smoothly curving line of occlusion.

Angle`s classification of malocclusion

Orthodontics was no longer just the alignment of irregular teeth.Angle and his followers strongly opposed extraction for orthodontic purpose.With the emphasis on dental occlusion that followed,however,less attention came to be paid to facial proportions and esthetics.

As time passed,it became clear that even an excellent occlusion was unsatisfactory if it was achieved at the expense of proper facial proportions.Not only were there esthetic problems,it often proved impossible to maintain an occlusal relationship.Extraction of teeth was reintroduced into orthodontics in the 1930s to enhance facial esthetics and achieve better stability of the occlusal relationships.

Cephalometric radiography enabled orthodontists to measure the changes in tooth and jaw positions produced by growth and treatment.These radiographs made it clear that many malocclusions resulted from faulty jaw relationships,not just malposed teeth.By use of cephalometrics,it also was possible to see that jaw growth could be altered by orthodontic treatment.

As the 21 st century begins,orthodontics differs from what was done previously in three important ways:
⑴ there is more emphasis now on dental and facial esthetics, and less on details of dental occlusion.

⑵ patients now expect and are granted a greater degree of involvement in planning treament 。 No longer is it appropriate for the paternalistic doctor to simply tell patients what treament they should have.

before treatment computer simulation post-treatment

⑶ orthodontics now is offered much frequently to older patients as part of a multidisciplinary treament plan involing other dental and medical specialties 。
（ Multidisciplinary Treatment ）
（ Interdisciplinary Treatment ）

The goal is not necessarily the best possible dental occlusion or facial esthetics but the best chance for long-term maintenance of the dention.This increased emphasis on treatment coordinated with other dentists has the effect of integrating orthodontics back into the main stream of dentistry,from which Angle’s teachings had tended to separate it.

⑴
：

⑵ Andrews ’s sixElements ：
1. Molar relationship
2. Crown angulation (Mesiodistal “tip”)
3. Crown inclination
4. Rotations
5. Spaces
6. Occlusal plane

五、 The relationship between orthodontics and other subjects
1 、
Prosthodontics
2 、 implantodontics
3 、 periodontics
4 、
Computer Technology
5 、
Materialogy

Tooth Extrusion

 enamel adhesive
 The super-elastic titanium alloy arch wire
 implant anchorage

应
变
不不锈钢丝
应力
奥 氏 体 钛 丝
丝

( extraoral force )

六、 methods
1. Preventive Orthodontics antenatal care regular oral examination
Get rid of bad habits space maintainer extractions of Supernumerary Teeth

serial extraction early treatment of crossbite

3. general Orthodontics
Removable appliances fixed appliances function appliances lnvisalign appliances

Edgewise Appliance

Dental digital modeling and invisible appliance
牙颌光固化在牙轿器技术流程中的位置
Dental data laminar analysis
Reverse correction appliance mold appliance

4. Orthodontics - Surgical correction
Orthognthic Surgery
Surgical Orthodontics
Distraction Osteogenesis

type of
Orthognathic surgery

Le Fort I 、 II 、 III osteotomy

(
Multijaw maxillary osteotomy )

Maxillar Impaction

oblique split ramus osteotomy sagittal split ramus osteotomy

Preparation before traction

zone of ossification

III traction
Anterior crossbite


 In the 20th century, major developments :
 Monobloc ， 1920 ， Pierre
 Edgewise ， 1928 ， Angle
 Begg 、 Straight-wire 、 Tipedge


X-cephalometry ， 1931 ， Broadbent
Eatraction ， 1941 ， Tweed
Orthodontic Materials and Bio-mechanics
 Wire Materials, gold, stainless steel, O wire, hotactivated, nickel, titanium and titanium ß
 Tooth movement, Burstone, power systems, force size, force direction
 Bonding technology
 Orthognathic surgery and orthodontics
 Computer applications 80`s

 In 21st century ,the direction of the development of orthodontics
 Craniofacial growth and development
 Biology of tooth movement
 Biomechanics and BioMaterials
 Computer use in orthodontics
 Three Dimensional Diagnosis
 Interdisciplinary Treatment

？？
What is the craniofacial growth pattern
？

8 months, 6 y, 8 y and 20 y old

一、 methods of collecting information longitudinal study cross-sectional study mixed longitudinal study

二、 1. Measurement Study
Craniometry
Anthropometry
Cephalometry

Craniometry
Cephalometry

Anthropometry

Anthropometry
• techniques for measuring living individuals
•
Three-dimensional structure
• surface measurement
• Poor accuracy
• The stability of the measurement system and method )
• The basis for evaluation of facial morphology
• studying the deep structure is impossible)

二、 2 . experiment
Vital staining
Radioactive Tracer
Implant radiography
Molecular Genetics

(Radioactive Tracer)
Implant radiography

三、 basic concept
1. （ Growth Patten ）
Pattern of facial growth ：
Average growth pattern
Horizontal growth pattern
Vertical growth pattern


 Growth
 Development

• Normal growth pattern
Changes in overall body proportions

Scammon’s Curve

Average growth pattern

Horizontal growth pattern
Vertical growth pattern

2. Variability
Everyone is not alike in the way that they grow as in everyting else.It can be difficult but clinically very important to decide whether an individual is merely at the extreme of the normal variation or falls outside the normal range.

 Racial and ethnic differences
 Gender
 Sickness
 nutrition
 Timing factor -Late/early maturers
 Problems with growth (hormones or genetics)

3. Timing
Variability in growth arises in several ways:from normal variation,from timing effects.Variation in timing arises because the same event happens for different individuals at different times.
developmental age and chronologic age

 Early, average, and late matuerers
 Chronological age vs. Developmental age

4.
Rapid phase of growth and development
Rapid and slow phase of craniofacial growth and development is close to rapid and slow phase of body growth and development .

 To determine optimum time for treatment
(growth modification and surgery)
 to determine the amount of growth left
 to determine type of growth

5.
Growth site and Growth center
A site of growth is merely a location at which growth occurs,whereas a center is a location at which independent (genetically controlled) growth occurs.All growth centers also are growth sites, whereas the reverse is not true.

For example, it is now known that the sutures between the membranous bones of the cranium and the maxilla that previously were considered as primary growth centers, actually are mere sites of growth.

 Do you know the hazards of Dentofacial deformities?
Orthodontic treatment goal?
What is ideal normal occlusion , what is individual normal occlusion ？
What is the growth pattern?
What is the growth site and growth center?

四、 postnatal Craniofacial Growth and
Development
1. Craniofacial dividing line
Bolton – nasion plane
Frankfort plane
Ba-N plane

Frankfort 平面
Bolton 鼻根平面， A line connecting points Bolton and
Nasion; an alternate representation of the cranial base.

全颅底平面（ N – Ba ）
To represent the cranial base more accurately than the SN line or the Bolton plane.
前颅底平面（ S-N ） Representing the anterior cranial base. A line joining points S and Na.

2. ways of Bone growth and development
⑴ surface apposition of bone periosteum osteoblast
⑵ interstitial growth osseous tissue
Connective tissue cells Fibroblast Collagen fibers and matrix calcification

⑶ central cartilage cell proliferate hypertrophy calcification
Peripheral cartilage
Cells of deep Connective tissue membrane differentiate into cartilage cells and matrix form hyaline cartilage, that calcifiy into new bone

Reserve zones ( RZ )
Proliferating zones ( PZ )
Prehypertrophic zones ( PHZ )
Hypertrophic zones ( HZ )

Reserve zones ( RZ )
Proliferating zones ( PZ )
Prehypertrophic zones ( PHZ )
Hypertrophic zones ( HZ )
Articular cartilage ( AC )
Growth cartilage ( GC )

3. Cranial growth and development
A. cranial cavity function ： protecting the brain structure ： flat bone
Site and mechanism of the growth ： suture and Surface hyperplasia

timing: （ 6-7 years old reach
90% of people ）
Clinical Significance ：
Aperts Syndrome

Major Features of Apert Syndrome
 Prematurely fused cranial sutures
 A retruded midface
 Fused fingers
 Fused toes

B. cranial base function ： stability growth site and timing ：
The growth of cartilage
（ intersphenoid synchondrosis 、 spheno-occipital synchondrosis 、 spheno-ethmoidal synchondrosis
）

Growth characteristics
： depth
> Height > Width
Clinical Significance : Hypoplasia cause deficiency of middle 1 / 3 face

4. Facial Growth and Development
A. Nasomaxillary Complex main Maxillary growth ， but septal cartilage growth conduct the growth of middle face importantly.

B. mandible growth: forward ,downward
Height > depth > Width

the rate of
Craniofacial growth

5. Maxillary Growth and Development
A. Passive displacement
The cranial base promote the growth of the maxillary, more important for child .

Passive displacement

B. active growth ： depth ： maxillary tuberosity
Alveolar bone growth
Horizontal part of palatine bone growth

the direction of maxillary movement
The suture between maxilla and cranium

颞颧缝
颧额缝
额颌缝
鼻颌缝
颧颌缝

palatal vault moves downward
The site of maxillary growth and absorption

：
：

height ： frontozygomatic and zygomaticomaxillary suture growth
Orbital floor reconstruction
Basis nasi moves downward
Alveolar bone growth

One side absorption the other side proliferation
The site of maxillary absorption

C. clinical application
• high vault
•
Restrict maxillary development
• maxillary protraction
•
Maxillary arch RPE

6.
Mandibular Growth and Development
A. function ：
The only movable bone of Craniofacial region 、 relevant to mastication 、 language 、 airway maintenance 、 countenance 。

B. growth and development ：
Partition
： body of mandible alveolar process
Mandibular ramus

functional protuberance ：
Attachment of muscles and teeth condylar process 、 coronoid process 、 angle of mandible 、 alveolar process

C. The site of growth and mechanisms ： condylar process ： fibrocartilage ， growth site 。 body of mandible ： outside surface of hyperplasia ， inside the absorption

C. The site of growth and mechanisms ：
Mandibular ramus ： posterior margin bone apposition
， anterior margin bone resorption alveolar bone ： impact the height of mandible

C. The site of growth and mechanisms ： height ： condylar process
、 alveolar bone growth length ： posterior margin bone apposition ， anterior margin bone resorption width ： condylar process growth
，
Lateral mandibular hyperplasia

D. characteristic ： angle of mandible ： it will be different with age,growth and masticatory function
。 newborn
：
140 – 160 degree
Adults ： 125 degree the elderly ： obtuser

D. characteristic ： the height of mandibular ramus ： the length of mandibular body newborn ： 35 ： 100 adults ： 65 ： 100 mental region ： protrusion vary due to the differences of race

E. Growth time ： the growth peak of mandibular height and length is basically the same with physical growth ， or a little ealier.
the peak time of adolescent period is the most important in growing period.The time for girls which is 1.5 years earlier than boys,come before menarche .

F. clinical application ： developmen change mandibular growth and functional appliance occlusal pad


“
V”shaped osteogenesis phenomenon
Enlow, Proposed the "V"-shaped Principle ：
Many facial bone and cranium have a "V" shaped structure . There are bone apposition in the medial
"V"-shape and bone absorption , lateral. So "V" shape move from one location to another , while all have increased in diameter.

The way of “V”shaped bone growth

 Congenital craniofacial malformations: cleft lip/palate, syndromes (Apert, Crouzon, etc..), craniosynostosis
 Non-syndromic craniosynostosis
 Trauma
 Ankylosis
 Juvenile rheumatoid arthritis

Trauma
 Blow to one side of the mandible may fracture the condylar process on the opposite side
 pull of the lateral pterygoid muscle distracts the condylar fragment including all the cartilage = resorption occurs

五、 Theories of growth and development
It is a truism that growth is strongly influnced by genetic factor.In order to understand the etiologic processes of malocclusion and dentofacial deformity,it is necessary to learn how facial growth is influncend and controlled.Exactly what determines the growth of the jaws,however,remains unclear and continus to be the subject of intensive research.

•
Bone theory
It implies that genetic control is expressed directly at the level of the bone,and therefore its locus should be the periosteum。

 Cartilage theory
Genetic control is expressed in the cartilage,while bone responds passively to being displaced.This
indirect genetic control is called epigenetic.

 Soft tissue matrix theroy
Genetic control is mediated to a large extent outside the skeletal system and that growth of both bone and cartilage is controlled epigenetically,occurring only in response to s signal from other tissues.
In contemporary thought, the truth is to be found in some synthesis of the second and third theories,while the first ,though it was the dominant view until 1960s,has largerly been discarded.

六、 Dentition , occlusal growth and development
（一） . Eruption of the primary teeth
1 eruption begins when the root has been formed.
2 the time of eruption are not different in gender ， are related to race and little relation with nutrition.
3 pairs of the same name erupt in the same time.

六、
Dentition , occlusal growth and development
（一） . Eruption of the primary teeth
4 the timing and sequece of eruption the mandibular central incisors will erupt first— 6 – 8months the maxillary second molars erupt at last— 2 -3years maxillary teeth erupt late than
Mandibular teeth.
sequence ： I II IV III V

六、
Dentition , occlusal growth and development
（二） .
Characteristics of primary dentition
5 flush terminal plane ：
Look at the distal aspect of the 2nd primary molar
Mesial step ： 60 - 70%
Mesio step
Disto step




 Disto step

Distal Mesial

Distal Mesial

Distal Mesial

Distal Mesial

THE THREE TYPES OF TERMINAL PLANES
FLUSH PLANE MESIAL STEP DISTAL STEP
TYPE TYPE TYPE

六、
Dentition , occlusal growth and development
（二） .
Characteristics of primary dentition
1 anterior teeth space
2
Primate space
3 shallow overjet ,overbite
4
ML side of maxillary primary canine contacts the DB side of madibular primary canine.

（三） . mixed dentition period
1 The eruption of permanent teeth: tooth germ moves in the alveolar bone, and finally comes out of bone
。 the deciduous root absorpted and root of permanent teeth continue to grow during eruption with the height of alveolar bone increasing.
Eruption conditions : crown fully formed ,roots start to form.

the eruption of the maxillary lateral incisor
8years
The eruption of the first permanent molar
6years

The eruption of first premolars, mandibular canines ， 11years
The complete eruption of the lateral incisor 9years

Permanent roots are fully formed
15years
Deciduous teeth have all been replaced
12years

1 .The eruption of permanent teeth:
Degree in the formation of the root is different
First permanent molars: 35 - 40%
Canine: 70%; first premolar: 50%
Second premolar: 50%
Second Molar: 25 - 30%

2 Eruption time and sequence time ： 6 — 12years sequence ： U 6 1 2 4 3 5 7
6 1 2 4 5 3 7
L 6 1 2 3 4 5 7
6 1 2 4 3 5 7

3. gap relationships in the process of tooth replacement :
The whole maxillary deciduous dentition: 68.2
The whole maxillary permanent dentition: 74.0
The whole mandibular deciduous dentition : 61.8
The whole mandibular permanent dentition : 64.4

3 space relations in replacement of teeth ：
When the replacement of anterior teeth:
Gap between deciduous anterior teeth
Permanent incisor when erupting tip forward
Deciduous canine displace
Arch width increase

Replacement of the posterior teeth :
Premolar erupt more buccally than deciduous teeth
(Milk canine + the first and second deciduous molars )Width> Replacement permanent teeth

Length change
Leeway space

Leeway Space ： upper ： 0.9 - 1.0 mm each side lower ： 1.7 - 2.0 mm each side

4 occlusal adjustment in the course of tooth relapment
The early replacement: apex to apex relationship between molars reason ： a the mesial movement L > U b growth to the forward L > U a neutral relationship.

5 temporary malocclusion in the mixed dentition years ：
Gap between Maxillary central incisor
Maxillary lateral incisor tilt distally when erupting
Permanent anterior teeth (especially mandibular) crowding mildly
Mild distal molar relationship (early mixed dentition)
Temporary deep overbite (early mixed dentition)

7 years old 9 years old 14 years old
Changes in the axial inclination due to the eruption of the maxillary anterior teeth
(Broadbent, 1957).

Late Mesial Shift (cont.)
FTP
Molar moves into this space...
Class I

Power balance :
Muscle
Periodontal tissue
Craniomaxillary Growth
Genetic
Nutrition
Chronic diseases
Bad habits
Function of factors


Summary
Growth way of craniofacial bones
 cellular level:
 Hypertrophy
 Hyperplasia
 Increased production of extracellular matrix




Growth of the Cranial Vault and Base
Growth of Maxilla (Nasomaxillary Complex)
Resorption 、 Apposition
Growth of Mandible
（
Length
、
Width
、
Height
）
Theories of Growth Control
 Bone
 Cartilage
 The soft tissue matrix in which the skeletal elements are embedded - 60’s
“Functional Matrix Theory” by Moss
 Growth of Occlusion




 the methods of Craniofacial Growth and
Development?
The development of maxilla and mandible , how to complete in three dimensions?
What is leeway space and what is its clinical significane ?
The manifestation of temporary malocclusion ,they can be adjusted at the process of growth and development ,why ?