OrthodonticsOrthodontics

Hospital of Stomatology,Xi’an Jiaotong UniversityHospital of Stomatology,Xi’an Jiaotong University

Department of OrthodonticsDepartment of Orthodontics

Professor ZhouHongProfessor ZhouHong

overviewoverview Orthodontics is a branch of Clinical StomatologyOrthodontics is a branch of Clinical Stomatology , the mechanisms of , the mechanisms of

major research and development of dentofacial deformities, major research and development of dentofacial deformities,

diagnosis, prevention and treatment.diagnosis, prevention and treatment.

OrthoOrthodonticsdontics Dentofacial OrthopedicsDentofacial Orthopedics

MalMalocclusionocclusion Dentofacial DeformityDentofacial Deformity

Orthodontics and Dentofacial orthopedics

Orthodontics and Dentofacial orthopedics

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

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

Orthodontics and Dentofacial orthopedics

What is What is Dentofacial Deformity ?Dentofacial Deformity ?

Dentofacial deformity

A malformation of the A malformation of the teethteeth, , jawsjaws and/or and/or faceface

characterized by disharmonies of characterized by disharmonies of sizesize,, form form

and/orand/or function function. The term encompasses . The term encompasses

problems such as problems such as malocclusionmalocclusion, , cleft lip and cleft lip and

palatepalate and other skeletal or soft tissue and other skeletal or soft tissue

anomaliesanomalies, or , or syndromessyndromes that involve the face that involve the face

and the dentoalveolar complex.and the dentoalveolar complex.

一、一、 The manifestation of Dentofacial The manifestation of Dentofacial DeformityDeformity

11 malposition of individual, abnormity of arch malposition of individual, abnormity of arch

formform ,tooth malalignment,tooth malalignment

22 maxillomandibular malrelationshipmaxillomandibular malrelationship

3 3 malrelationship between jaw and craniummalrelationship between jaw and cranium

（ Microdontia ） （ Anterior crossbite ）

（ Spaces ） （ Suprenumerary tooth ）

（（ Congenital missing toothCongenital missing tooth ））

（（ Ectopic eruptionEctopic eruption ））

Bimaxillary DentoalveolarBimaxillary Dentoalveolar ProtrusionProtrusion and Crowdingand Crowding

（ Deep Overbite and Overjet ）

Deep overjet 11.0

mm

Deep overbite

90 %

（（ DeepDeep OverbiteOverbite withwith CrowdingCrowding ））

Mandibular prognathismMandibular prognathism

Maxillar Retrusion with Mandibular Protrusion

Mandibular prognathism

Maxillary retrognathism

Narrow of upper arch

（ Edge-to-edge biteEdge-to-edge bite ））

Crowding with edge-to edge bite

Bimaxillary dentoalveolar protrusionBimaxillary dentoalveolar protrusion

(frontal view)

(Lateral view )

Open bite

(frontal view)

(Lateral view )

Mandibular Shift

(frontal view)

(Lateral view )

Introversion deep overbite

二、二、 epidemiology epidemiology

prevalence rareprevalence rare ： ： 60`s:60`s: 29.33% - 48.87%29.33% - 48.87%

2000`s:2000`s: 51.84 – 72.92% 51.84 – 72.92%

Individual Normal OcclusionIndividual Normal Occlusion

Ideal Normal Occlusion Ideal Normal Occlusion

Incisor Irregularity Index Incisor Irregularity Index

A+B+C+D+E= Anterior lower incisor crowding

0-1 ideal0-1 ideal2-3 mild crowding2-3 mild crowding4-6 moderate crowding4-6 moderate crowding7-10 severe crowding7-10 severe crowding> 10 extreme crowding> 10 extreme crowding

三、 三、 Perniciousness Perniciousness

11 psychosocial influences psychosocial influences

22 oral function oral function

3 3 relation to dental diseaserelation to dental disease

44 Aesthetic impact Aesthetic impact

Relation between size of overjet and

prevalence of traumatised anterior teeth

Overjet (mm) Incidence % 5 22 9 24 >9 44

Dr Sarver:Dr Sarver:

Malocclusion of teeth is not disease , Malocclusion of teeth is not disease ,

rather, it is a disability with a potential rather, it is a disability with a potential

influence on physical and mental health.influence on physical and mental health.

Orthodontics Orthodontics — — current principles and techniquescurrent principles and techniques

2000 By Graber2000 By Graber

Reason for orthodontics

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、 standard and target

11 、 、 changeschanges of targetof target Crowed,irregular and protruding teeth have Crowed,irregular and protruding teeth have

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

1850 the first texts that 1850 the first texts that

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

Their emphasis in orthodontics remaind the Their emphasis in orthodontics remaind the

alignment of the teeth and the correction of facial alignment of the teeth and the correction of facial

proportions. Little attention was paid to the dental proportions. Little attention was paid to the dental

occlusion.In an era when an intact dentition was a occlusion.In an era when an intact dentition was a

rarity,the details of occlusal relationships were rarity,the details of occlusal relationships were

considered unimportant.considered unimportant.

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

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

Angle`s classification of malocclusion

Orthodontics was no longer just the alignment of Orthodontics was no longer just the alignment of

irregular teeth.Angle and his followers strongly irregular teeth.Angle and his followers strongly

opposed extraction for orthodontic purpose.With the opposed extraction for orthodontic purpose.With the

emphasis on dental occlusion that emphasis on dental occlusion that

followed,however,less attention came to be paid to followed,however,less attention came to be paid to

facial proportions and esthetics.facial proportions and esthetics.

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

Cephalometric radiography enabled orthodontists Cephalometric radiography enabled orthodontists

to measure the changes in tooth and jaw positions to measure the changes in tooth and jaw positions

produced by growth and treatment.These radiographs produced by growth and treatment.These radiographs

made it clear that many malocclusions resulted from made it clear that many malocclusions resulted from

faulty jaw relationships,not just malposed teeth.By use faulty jaw relationships,not just malposed teeth.By use

of cephalometrics,it also was possible to see that jaw of cephalometrics,it also was possible to see that jaw

growth could be altered by orthodontic treatment.growth could be altered by orthodontic treatment.

As the 21As the 21st st century begins,orthodontics century begins,orthodontics

differs from what was done previously in differs from what was done previously in

three important ways:three important ways:

⑴ ⑴ there is more emphasis now on there is more emphasis now on

dental and facial esthetics, and less on dental and facial esthetics, and less on

details of dental occlusion.details of dental occlusion.

⑵⑵ patients now expect and are granted a patients now expect and are granted a

greater degree of involvement in planning greater degree of involvement in planning

treamenttreament 。。 No longer is it appropriate for the No longer is it appropriate for the

paternalistic doctor to simply tell patients what paternalistic doctor to simply tell patients what

treament they should have.treament they should have.

computer simulation post-treatmentpost-treatment

before before treatmenttreatment

⑶ ⑶ orthodontics now is offered much orthodontics now is offered much

frequently to older patients as part of a frequently to older patients as part of a

multidisciplinary treament plan involing multidisciplinary treament plan involing

other dental and medical specialtiesother dental and medical specialties 。。

（（ Multidisciplinary Treatment Multidisciplinary Treatment ））

（（ Interdisciplinary Treatment Interdisciplinary Treatment ））

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

⑴ ⑴ targettarget ： ： HarmonyHarmony

StableStable

AestheticAesthetic

⑵ ⑵ Andrews ’s sixElements Andrews ’s sixElements ：：1. Molar relationship1. Molar relationship

2. Crown angulation (Mesiodistal “tip”) 2. Crown angulation (Mesiodistal “tip”)

3. Crown inclination 3. Crown inclination

4. Rotations 4. Rotations

5. Spaces 5. Spaces

6. Occlusal plane6. Occlusal plane

五、五、 The relationship between orthodontics The relationship between orthodontics

and other subjects and other subjects

11 、、 ProsthodonticsProsthodontics

22 、、 implantodontics implantodontics

33 、 、 periodonticsperiodontics

44 、、 Computer TechnologyComputer Technology

55 、 、 MaterialogyMaterialogy

Tooth Extrusion

significant development in stomatology are related to materials

enamel adhesiveenamel adhesive The super-elastic titanium alloy arch wireThe super-elastic titanium alloy arch wire implant anchorageimplant anchorage

不 不 锈 钢丝

马氏体钛丝

奥氏体钛丝丝

应力应力

应变

((extraoral forceextraoral force ))

六、六、 methodsmethods

1. Preventive Orthodontics1. Preventive Orthodontics antenatal careantenatal care

regular oral examination regular oral examination

Get rid of bad habits Get rid of bad habits

space maintainerspace maintainer

extractions of Supernumerary Teeth extractions of Supernumerary Teeth

2. Interceptive Orthodontics2. Interceptive Orthodontics

serial extractionserial extraction

early treatment of crossbiteearly treatment of crossbite

3. general Orthodontics3. general Orthodontics

Removable appliances

fixed appliances

function appliances

lnvisalignlnvisalign appliances appliances

可摘式矫治器可摘式矫治器

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 4. Orthodontics - Surgical

correctioncorrection

Orthognthic Surgery Orthognthic Surgery

Surgical OrthodonticsSurgical Orthodontics

Distraction OsteogenesisDistraction Osteogenesis

type of type of Orthognathic Orthognathic surgerysurgery

Le Fort ILe Fort I 、、 IIII 、、 III III osteotomyosteotomy

((Multijaw maxillary osteotomy )Multijaw maxillary osteotomy )

Maxillar ImpactionMaxillar Impaction

obliqueoblique split split ramus ramus osteotomyosteotomy

sagittal split sagittal split ramus ramus osteotomyosteotomy

Preparation before traction

zone of ossification

Anterior

crossbite

III traction

In the 20th century, major developments :In the 20th century, major developments : MonoblocMonobloc ，， 19201920 ，， PierrePierre EdgewiseEdgewise ，， 19281928 ，， AngleAngle

BeggBegg 、、 Straight-wireStraight-wire 、、 TipedgeTipedge X-cephalometryX-cephalometry ，， 19311931 ，， BroadbentBroadbent EatractionEatraction ，， 19411941 ，， TweedTweed

Orthodontic Materials and Bio-mechanicsOrthodontic Materials and Bio-mechanics Wire Materials, gold, stainless steel, O wire, hot-Wire Materials, gold, stainless steel, O wire, hot-

activated, nickel, titanium and titanium ßactivated, nickel, titanium and titanium ß Tooth movement, Burstone, power systems, force Tooth movement, Burstone, power systems, force

size, force directionsize, force direction Bonding technologyBonding technology Orthognathic surgery and orthodonticsOrthognathic surgery and orthodontics Computer applicationsComputer applications 80`s 80`s

In 21st century ,the direction of the development In 21st century ,the direction of the development

of orthodonticsof orthodontics

Craniofacial growth and developmentCraniofacial growth and development

Biology of tooth movementBiology of tooth movement

Biomechanics and BioMaterialsBiomechanics and BioMaterials

Computer use in orthodonticsComputer use in orthodontics

Three Dimensional DiagnosisThree Dimensional Diagnosis

Interdisciplinary TreatmentInterdisciplinary Treatment

Craniofacial Growth and Craniofacial Growth and

DevelopmentDevelopment

Why should we study the growth and development？？

What is the craniofacial growth pattern ？

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

Craniofacial Growth and Craniofacial Growth and DevelopmentDevelopment

一、一、 methods of collecting informationmethods of collecting information

longitudinal study longitudinal study

cross-sectional study  cross-sectional study 

mixed longitudinal studymixed longitudinal study

二、二、 1. 1. Measurement StudyMeasurement Study

CraniometryCraniometry

AnthropometryAnthropometry

Cephalometry Cephalometry

CraniometryCraniometry

CephalometryCephalometry

AnthropometryAnthropometry

•techniques for measuring living techniques for measuring living individualsindividuals

• Three-dimensional structure Three-dimensional structure

•surface measurementsurface measurement

•Poor accuracy Poor accuracy

•The stability of the measurement The stability of the measurement system and method )system and method )

•The basis for evaluation of facial The basis for evaluation of facial morphology morphology

•studying the deep structure is studying the deep structure is impossible)impossible)

Anthropometry Anthropometry

二、二、 2 .2 . experimentexperiment

Vital stainingVital staining

Radioactive TracerRadioactive Tracer

Implant radiographyImplant radiography

Molecular GeneticsMolecular Genetics

Implant radiographyImplant radiography

(Radioactive Tracer)(Radioactive Tracer)

三、 三、 basic conceptbasic concept

1. 1. （（ Growth PattenGrowth Patten ））

Pattern of facial growth Pattern of facial growth ：：    

Average growth patternAverage growth pattern

Horizontal growth patternHorizontal growth pattern   Vertical growth patternVertical growth pattern

Growth and Development

TerminologyTerminology GrowthGrowth DevelopmentDevelopment

Pattern

• Normal growth pattern Changes in overall body proportions

Pattern

Scammon’s Curve

Average growth patternAverage growth pattern

Vertical growth Vertical growth patternpattern

Horizontal Horizontal growth patterngrowth pattern

2. Variability2. Variability

Everyone is not alike in the way Everyone is not alike in the way

that they grow as in everyting else.It can that they grow as in everyting else.It can

be difficult but clinically very important be difficult but clinically very important

to decide whether an individual is merely to decide whether an individual is merely

at the extreme of the normal variation or at the extreme of the normal variation or

falls outside the normal range.falls outside the normal range.

Variability

Racial and ethnic differencesRacial and ethnic differences GenderGender SicknessSickness nutritionnutrition Timing factor -Late/early maturersTiming factor -Late/early maturers Problems with growth (hormones or genetics)Problems with growth (hormones or genetics)

3. Timing 3. Timing Variability in growth arises in Variability in growth arises in

several ways:from normal variation,from several ways:from normal variation,from timing effects.Variation in timing arises timing effects.Variation in timing arises because the same event happens for because the same event happens for different individuals at different times.different individuals at different times.

developmental age and chronologic agedevelopmental age and chronologic age

Timing Variation

Early, average, and late matuerersEarly, average, and late matuerers Chronological age vs. Developmental ageChronological age vs. Developmental age

4.4. Rapid phase of growth and development Rapid phase of growth and development

Rapid and slow phase of Rapid and slow phase of

craniofacial growth and development is craniofacial growth and development is

close to rapid and slow phase of body close to rapid and slow phase of body

growth and development .growth and development .

Why do we assess growth?

To determine optimum time for treatment To determine optimum time for treatment (growth modification and surgery)(growth modification and surgery)

to determine the amount of growth leftto determine the amount of growth left to determine type of growthto determine type of growth

5.5. Growth site and Growth centerGrowth site and Growth center

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

Growth Center and Growth SiteGrowth Center and Growth Site

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

Questions

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

四、四、 postnatal Craniofacial Growth and postnatal Craniofacial Growth and DevelopmentDevelopment

1. 1. Craniofacial dividing lineCraniofacial dividing line

Bolton – nasionBolton – nasion planeplane

FrankfortFrankfort planeplane

Ba-N planeBa-N plane

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

FrankfortFrankfort 平面平面

全颅底平面（全颅底平面（ N – BaN – Ba ））To represent the cranial base more To represent the cranial base more accurately than the SN line or the Bolton accurately than the SN line or the Bolton plane.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 2. ways of Bone growth and

developmentdevelopment

⑴ ⑴ surface apposition of bonesurface apposition of bone

periosteumperiosteum osteoblastosteoblast osseous tissueosseous tissue

⑵ ⑵ interstitial growthinterstitial growth

Connective tissue cells Fibroblast Collagen Connective tissue cells Fibroblast Collagen

fibers and matrix calcificationfibers and matrix calcification

⑶ ⑶ central cartilage cell proliferate central cartilage cell proliferate

hypertrophy  hypertrophy   Peripheral cartilage Peripheral cartilage

calcificationcalcification

Cells ofCells of deep Connective tissue membrane deep Connective tissue membrane

differentiate into cartilage cells and matrix form differentiate into cartilage cells and matrix form hyaline cartilage, that calcifiy into new bonehyaline 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 3. Cranial growth and development

A. A. cranial cavitycranial cavity

functionfunction ：： protecting the brain protecting the brain

structurestructure ：： flat boneflat bone

Site and mechanism of the growth Site and mechanism of the growth ：：suture and Surface hyperplasiasuture and Surface hyperplasia

timing:timing: （（ 6-7 years old 6-7 years old

reach 90% of people reach 90% of people ）） Clinical SignificanceClinical Significance ： ：

Aperts Syndrome Aperts Syndrome

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

B. cranial baseB. cranial base

functionfunction ：： stabilitystability

growth site and timinggrowth site and timing ：： The The

growth of cartilage growth of cartilage

（（ intersphenoid synchondrosisintersphenoid synchondrosis 、、 spheno-occipital spheno-occipital

synchondrosissynchondrosis 、、 spheno-ethmoidal spheno-ethmoidal

synchondrosissynchondrosis ））

Growth characteristicsGrowth characteristics ：： depthdepth

>>HeightHeight > > WidthWidth

Clinical SignificanceClinical Significance :: Hypoplasia cause Hypoplasia cause

deficiencydeficiency of middle 1 / 3 facemiddle 1 / 3 face

4. Facial Growth and Development 4. Facial Growth and Development

A. Nasomaxillary ComplexA. Nasomaxillary Complex

main Maxillary growthmain Maxillary growth ，， but but

septal cartilage growth conduct the septal cartilage growth conduct the

growth of middle face importantly.growth of middle face importantly.

B. mandibleB. mandible

growth:growth: forward ,downwardforward ,downward

Height > depth > Width Height > depth > Width

the rate of Craniofacial growth

5. Maxillary Growth and Development5. Maxillary Growth and Development

A. Passive displacement A. Passive displacement

The cranial base promote the growth of The cranial base promote the growth of

the maxillary, more important for child .the maxillary, more important for child .

Passive Passive displacementdisplacement

B. active growthB. active growth ：： depthdepth ：： maxillary tuberosity maxillary tuberosity

Alveolar bone growth Alveolar bone growth

Horizontal part of palatine bone growthHorizontal part of palatine bone growth

The suture between maxilla and cranium

the direction of maxillary movement

颞颧缝

颧颌缝

颧额缝

额颌缝

鼻颌缝

The site of maxillary growth and absorption

palatal vault moves downward

B. active growthB. active growth ：： widthwidth ：： median palatine median palatine

suturesuture growth

Buccal surface of maxillary Buccal surface of maxillary

bone hyperplasiabone hyperplasia

Alveolar bone growthAlveolar bone growth

heightheight ：： frontozygomatic and frontozygomatic and

 zygomaticomaxillary suture   growth  zygomaticomaxillary suture   growth

Orbital floorOrbital floor

reconstructionreconstruction

Basis nasi moves Basis nasi moves

downwarddownward

Alveolar bone growthAlveolar bone growth

The site of maxillary absorption

One side absorptionthe other side proliferation

C. C. clinical applicationclinical application

• high vault high vault

• Restrict maxillary Restrict maxillary developmentdevelopment

• maxillary protractionmaxillary protraction

• Maxillary arch RPEMaxillary arch RPE

6. 6. Mandibular Growth and DevelopmentMandibular Growth and Development

A. functionA. function ：： The only movable bone of Craniofacial The only movable bone of Craniofacial

regionregion 、、 relevant to relevant to

mastication mastication 、、 language language 、、 airway airway maintenancemaintenance 、、 countenancecountenance 。。

B. growth and developmentB. growth and development ：： PartitionPartition ：： body of mandiblebody of mandible

alveolar processalveolar process

Mandibular Mandibular

ramusramus

functional protuberancefunctional protuberance ：： Attachment of muscles and teethAttachment of muscles and teeth

condylar processcondylar process 、、 coronoid coronoid

processprocess 、、 angle of mandible  angle of mandible   、、 alveolar processalveolar process

C. The site of growth and mechanismsC. The site of growth and mechanisms

：：condylar processcondylar process ：： fibrocartilage fibrocartilage ，， growth site growth site 。。

body of mandiblebody of mandible ：： outside surface of hyperplasia outside surface of hyperplasia

， ， inside the absorption inside the absorption

C. The site of growth and mechanismsC. The site of growth and mechanisms ：： Mandibular ramus Mandibular ramus ：： posterior margin bone posterior margin bone

apposition apposition ，， anterior margin bone resorption anterior margin bone resorption

alveolar bonealveolar bone ：： impact the height of mandibleimpact the height of mandible

C. The site of growth and mechanismsC. The site of growth and mechanisms：：

heightheight ：： condylar processcondylar process 、、 alveolar bone alveolar bone

growthgrowth

lengthlength ： ： posterior margin bone apposition posterior margin bone apposition

，， anterior margin bone resorption anterior margin bone resorption

widthwidth ：： condylar process growthcondylar process growth ，， Lateral Lateral

mandibular hyperplasia mandibular hyperplasia

D. characteristicD. characteristic ：： angle of mandible angle of mandible ：： it will be different with it will be different with

age,growth and masticatory function age,growth and masticatory function 。。newborn newborn ： ： 140 – 160 degree140 – 160 degreeAdults Adults ： ： 125 degree125 degreethe elderly the elderly ： ： obtuser obtuser

D. characteristicD. characteristic ：： the height of mandibular ramus the height of mandibular ramus ：： the the

length of mandibular bodylength of mandibular body

newbornnewborn ： ： 35 35 ：： 100100

adultsadults ： ： 65 65 ：： 100100

mental regionmental region ：： protrusion vary protrusion vary

due to the differences of racedue to the differences of race

E. Growth time E. Growth time ：： the growth peak ofthe growth peak of mandibular height and length is mandibular height and length is

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

F. clinical applicationF. clinical application ：： change mandibular growth change mandibular growth

and developmenand developmen

functional appliancefunctional appliance

occlusal padocclusal 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

When things go wrong

Congenital craniofacial malformations: cleft Congenital craniofacial malformations: cleft lip/palate, syndromes (Apert, Crouzon, lip/palate, syndromes (Apert, Crouzon, etc..), craniosynostosisetc..), craniosynostosis

Non-syndromic craniosynostosisNon-syndromic craniosynostosis TraumaTrauma AnkylosisAnkylosis Juvenile rheumatoid arthritis Juvenile rheumatoid arthritis

When things go wrong

Trauma Blow to one side of Blow to one side of

the mandible may the mandible may fracture the condylar fracture the condylar process on the process on the opposite sideopposite side

pull of the lateral pull of the lateral pterygoid muscle pterygoid muscle distracts the condylar distracts the condylar fragment including all fragment including all the cartilage = the cartilage = resorption occursresorption occurs

五、五、 Theories of growth and developmentTheories of growth and development

It is a truism that growth is strongly influnced by It is a truism that growth is strongly influnced by

genetic factor.In order to understand the etiologic genetic factor.In order to understand the etiologic

processes of malocclusion and dentofacial deformity,it processes of malocclusion and dentofacial deformity,it

is necessary to learn how facial growth is influncend is necessary to learn how facial growth is influncend

and controlled.Exactly what determines the growth of and controlled.Exactly what determines the growth of

the jaws,however,remains unclear and continus to be the jaws,however,remains unclear and continus to be

the subject of intensive research.the subject of intensive research.

• Bone theoryBone theory

It implies that genetic It implies that genetic

control is expressed control is expressed

directly at the level of the directly at the level of the

bone,and therefore its bone,and therefore its

locus should be the locus should be the

periosteumperiosteum 。。

Cartilage theoryCartilage 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 theroySoft 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、六、 Dentition , occlusal growth and Dentition , occlusal growth and

developmentdevelopment

（一）（一） . Eruption of the primary teeth. Eruption of the primary teeth

1 eruption begins when the root has 1 eruption begins when the root has beenbeen formed.formed.

2 the time of eruption are not 2 the time of eruption are not different in gender different in gender ，， are related to race are related to race and little relation with nutrition.and little relation with nutrition.

3 pairs of the same name erupt in 3 pairs of the same name erupt in the same time.the same time.

六、六、 Dentition , occlusal growth and developmentDentition , occlusal growth and development

（一）（一） . Eruption of the primary teeth. Eruption of the primary teeth 4 the timing and sequece of eruption4 the timing and sequece of eruption

the mandibular central incisors will the mandibular central incisors will erupt first— 6 – 8monthserupt first— 6 – 8months

the maxillary second molars erupt the maxillary second molars erupt at last— 2 -3yearsat last— 2 -3years

maxillary teeth erupt late than maxillary teeth erupt late than Mandibular teeth.Mandibular teeth.

sequence sequence ： ： I II IV III VI II IV III V

六、六、 Dentition , occlusal growth and developmentDentition , occlusal growth and development

（二）（二） . . Characteristics of primary dentitionCharacteristics of primary dentition

5 flush terminal plane5 flush terminal plane ：： Look at the distal aspect of the 2nd Look at the distal aspect of the 2nd

primary molar primary molar Mesial step Mesial step ： ： 60 - 70%60 - 70%

Mesio stepMesio step

Disto stepDisto step

Positioning of Primary Teeth

Classification of Occlusion of the Primary Second Molar

Look at the distal aspect of the 2nd molar Look at the distal aspect of the 2nd molar Flush terminal plane Flush terminal plane Mesial step Mesial step Mesio stepMesio step Disto step Disto step

Distal Mesial

Flush Terminal PlaneFlush Terminal Plane

Distal Mesial

Mesial StepMesial Step

Distal Mesial

Mesio StepMesio Step

Distal Mesial

Disto StepDisto Step

THE THREE TYPES OF TERMINAL PLANES

FLUSH PLANE MESIAL STEP DISTAL STEP

TYPE TYPE TYPE

六、六、 Dentition , occlusal growth and developmentDentition , occlusal growth and development

（二）（二） . . Characteristics of primary dentitionCharacteristics of primary dentition

1 1 anterior teeth spaceanterior teeth space

2 2 Primate spacePrimate space

3 3 shallow overjet ,overbiteshallow overjet ,overbite

4 4 ML side of maxillary primary canine contacts ML side of maxillary primary canine contacts

the DB side of madibular primary canine. the DB side of madibular primary canine.

No Primary Spacing

（三）（三） . mixed dentition period. mixed dentition period

1 The eruption of permanent teeth: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 first permanent molar

6years

the eruption of the maxillary lateral

incisor8years

The complete eruption of the

lateral incisor 9years

The eruption of first premolars, mandibular canines ， 11years

Deciduous teeth have all been replaced

12years

Permanent roots are fully formed

15years

1 .The eruption of permanent teeth:1 .The eruption of permanent teeth:

Degree in the formation of the root is Degree in the formation of the root is differentdifferent

First permanent molars: 35 - 40% First permanent molars: 35 - 40% Canine: 70%; first premolar: 50% Canine: 70%; first premolar: 50% Second premolar: 50% Second premolar: 50% Second Molar: 25 - 30% Second Molar: 25 - 30%

2 Eruption time and sequence2 Eruption time and sequence

timetime ： ： 6 — 12years6 — 12years sequencesequence ：： U 6 1 2 4 3 5 7U 6 1 2 4 3 5 7

6 1 2 4 5 3 76 1 2 4 5 3 7 L 6 1 2 3 4 5 7L 6 1 2 3 4 5 7 6 1 2 4 3 5 76 1 2 4 3 5 7

3. gap relationships in the process of tooth 3. gap relationships in the process of tooth replacement :replacement :

The whole maxillary deciduous dentition: 68.2 The whole maxillary deciduous dentition: 68.2

The whole maxillary permanent dentition: 74.0 The whole maxillary permanent dentition: 74.0

The whole mandibular deciduous dentition : 61.8 The whole mandibular deciduous dentition : 61.8

The whole mandibular permanent dentition : 64.4The whole mandibular permanent dentition : 64.4

3 space relations in replacement of3 space relations in replacement of teethteeth ：：

When the replacement of anterior When the replacement of anterior teeth:teeth:

Gap between deciduous anterior Gap between deciduous anterior teethteeth

Permanent incisor when erupting Permanent incisor when erupting tip forwardtip forward

Deciduous canine displaceDeciduous canine displace

Arch width increaseArch width increase

Replacement of the posterior teeth :Replacement of the posterior teeth :

Premolar erupt more buccally than deciduous teeth Premolar erupt more buccally than deciduous teeth

(Milk canine + the first and second (Milk canine + the first and second deciduous molars )Width> Replacement deciduous molars )Width> Replacement permanent teethpermanent teeth

Leeway space

Length change

Leeway SpaceLeeway Space ：：

upperupper ： ： 0.9 - 1.0 mm each side0.9 - 1.0 mm each side

lowerlower ： ： 1.7 - 2.0 mm each side1.7 - 2.0 mm each side

4 occlusal adjustment in the course of tooth 4 occlusal adjustment in the course of tooth

relapmentrelapment The early replacement: apex to apex relationship between

molars

reasonreason ：： a the mesial movement L > Ua the mesial movement L > U b growth to the forward L > Ub growth to the forward L > U

a neutral relationship.

5 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).

FTP Class IMolar moves into this space...

LateLate MesialMesial Shift (cont.)Shift (cont.)

The factors that affect occlusal buldingPower balance :Power balance : Muscle Muscle Periodontal tissuePeriodontal tissue

Craniomaxillary Growth Craniomaxillary Growth

Genetic Genetic

Nutrition Nutrition

Chronic diseases Chronic diseases

Bad habits Bad habits

Function of factorsFunction of factors

SummarySummary Growth way of craniofacial bones Growth way of craniofacial bones

cellular level: cellular level: HypertrophyHypertrophy HyperplasiaHyperplasia Increased production of extracellular matrixIncreased production of extracellular matrix

Growth of the Cranial Vault and BaseGrowth of the Cranial Vault and Base Growth of Maxilla (Nasomaxillary Complex) Growth of Maxilla (Nasomaxillary Complex) Resorption Resorption 、、 AppositionApposition

Growth of MandibleGrowth of Mandible （（ LengthLength 、、 WidthWidth 、、 HeightHeight ）） Theories of Growth ControlTheories of Growth Control

BoneBone CartilageCartilage The soft tissue matrix in which the skeletal elements are embedded - 60’s The soft tissue matrix in which the skeletal elements are embedded - 60’s

“Functional Matrix Theory” by Moss“Functional Matrix Theory” by Moss

Growth of OcclusionGrowth of Occlusion

Questions

the methods of Craniofacial Growth and the methods of Craniofacial Growth and Development?Development?

The development of maxilla and mandible , how to The development of maxilla and mandible , how to complete in three dimensions?complete in three dimensions?

What is leeway space and what is its clinical What is leeway space and what is its clinical significane ?significane ?

The manifestationThe manifestation of temporary malocclusion ,they of temporary malocclusion ,they can be adjusted at the process of growth and can be adjusted at the process of growth and development ,why ?development ,why ?