B. growth and development

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Orthodontics
Hospital of Stomatology,Xi’an Jiaotong University
Department of Orthodontics
Professor ZhouHong
overview
Orthodontics is a branch of Clinical Stomatology , the mechanisms of
major research and development of dentofacial deformities,
diagnosis, prevention and treatment.
Orthodontics
Dentofacial Orthopedics
Malocclusion
Dentofacial Deformity
Orthodontics and Dentofacial orthopedics
Orthodontics and Dentofacial orthopedics

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.
Orthodontics and Dentofacial orthopedics

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.
What is Dentofacial Deformity ?
Dentofacial deformity

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)
(Spaces)
(Anterior crossbite)
(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
(frontal view)
(Lateral view )
Open bite
(frontal view)
(Lateral view )
Mandibular Shift
(frontal view)
(Lateral 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、 Perniciousness
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)
5
9
>9
Incidence %
22
24
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
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
1、 changes
of target
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 21st 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.
computer simulation
before
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 target: Harmony
Stable
Aesthetic
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
significant development in
stomatology are related to materials
enamel adhesive
 The super-elastic titanium alloy arch wire
 implant anchorage

不不锈钢丝
应
变
奥氏体钛丝
丝
应力
(extraoral force )
六、methods
1. Preventive Orthodontics
antenatal care
regular oral examination
Get rid of bad habits
space maintainer
extractions of Supernumerary Teeth
2. Interceptive Orthodontics
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
sagittal split
ramus
osteotomy
oblique split
ramus
osteotomy
Preparation before traction
zone of ossification
Anterior
crossbite
III traction
 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
Craniofacial Growth and
Development
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
Development
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
Implant radiography
(Radioactive Tracer)
三、 basic concept
1. (Growth Patten)
Pattern of facial growth :
Average growth pattern
Horizontal growth pattern
Vertical growth pattern
Growth and Development
 Terminology
Growth
 Development

Pattern
• Normal growth pattern
Changes in overall body proportions
Pattern
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.
Variability
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
Timing Variation
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 .
Why do we assess growth?
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.
Growth Center and Growth Site
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.
Questions

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
Bolton - 鼻根平面, A line
connecting points Bolton and
Nasion; an alternate representation
of the cranial base.
Frankfort平面
前颅底平面(S-N)Representing
the anterior cranial base. A line
joining points S and Na.
全颅底平面(N – Ba)
To represent the cranial base more
accurately than the SN line or the Bolton
plane.
2. ways of Bone growth and
development
⑴ surface apposition of bone
periosteum
osteoblast
⑵ interstitial
Connective tissue cells
fibers and matrix
osseous tissue
growth
Fibroblast
calcification
Collagen
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 suture
between maxilla
and cranium
the direction of
maxillary
movement
颧额缝
额颌缝
鼻颌缝
颧颌缝
颞颧缝
The site of maxillary
growth and absorption
palatal vault
moves
downward
B. active growth:
width:median palatine
suture growth
Buccal surface of maxillary
bone hyperplasia
Alveolar bone growth
height:frontozygomatic
and zygomaticomaxillary suture growth
Orbital floor reconstruction
Basis nasi moves downward
Alveolar bone growth
The site of
maxillary
absorption
One side absorption
the other side
proliferation
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:
change mandibular growth and
developmen
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
When things go wrong
Congenital craniofacial malformations: cleft
lip/palate, syndromes (Apert, Crouzon,
etc..), craniosynostosis
 Non-syndromic craniosynostosis
 Trauma
 Ankylosis
 Juvenile rheumatoid arthritis

When things go wrong

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
Positioning of Primary Teeth
Classification of Occlusion of the
Primary Second Molar
Look at the distal aspect of the 2nd molar
 Flush terminal plane
 Mesial step
 Mesio step
 Disto step
Flush Terminal Plane
Distal
Mesial
Mesial Step
Distal
Mesial
Mesio Step
Distal
Mesial
Disto Step
Distal
Mesial
THE THREE TYPES OF TERMINAL PLANES
FLUSH PLANE
TYPE
MESIAL STEP
TYPE
DISTAL STEP
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.
No Primary Spacing
(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 first
permanent molar
6years
the eruption of the
maxillary lateral
incisor
8years
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:
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
L6 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
Replacement of the posterior teeth :
Premolar erupt more buccally than deciduous teeth
(Milk canine + the first and second
deciduous molars )Width> Replacement
permanent teeth
Leeway space
Length change
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
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
The factors that affect occlusal bulding
Power balance :
Muscle
Periodontal tissue
Craniomaxillary Growth
Genetic
Nutrition
Chronic diseases
Bad habits
Function of factors
Summary

Growth way of craniofacial bones

cellular level:







Growth of the Cranial Vault and Base
Growth of Maxilla (Nasomaxillary Complex) Resorption 、Apposition
Growth of Mandible (Length、Width、Height)
Theories of Growth Control




Hypertrophy
Hyperplasia
Increased production of extracellular matrix
Bone
Cartilage
The soft tissue matrix in which the skeletal elements are embedded - 60’s
“Functional Matrix Theory” by Moss
Growth of Occlusion
Questions




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 ?
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