Atlas of Orthodontics Principles and Cinical Applications ppt

\
•
Atlas
of
•
Principles and
ical Applications
,
•
Atlas
of
Anthony
D.
VIazis, DDS,
MS
A
ss
istant Professor
Dep
artme
nt
of Orthodontics
Ba
ylor College of Dentis
tr
y
Dalla
s,
Tex
as

Principles
and
ical
Applications
W.B. Saunders Company
A
DiI
'isioti
if
Ifarra1m Broce & Company
Philade
lp
hia
london
Toronto
Mo
nt
rea
l
Syd
n
ey
Tok
yo
Preface
•
Atlas
of
Orthodontics: Principles and
Cl

inical Applications was written with the
intention to introduce to the world
of
clinical orthodontics its first illustrated text.
This colorful. methodological presentation
of
the most up-t<rdate
inf
o
nnation
and
direct clinic
al
application aims to aid the students
of
orthodontics in understanding
the logical sequence
fr
om diagnosis to a succe
ss
ful
treatment. In addi
ti
on. as the
innovations and revolutionary improvements
in
clinic
al
orthodontics over
re

cent
years have widened the scope
of
diagnosis and broadened the horizons of treatment.
this work aims to serve as the most updated illustrated reference of
all
these new
advanc
es.
Thus, the atlas can very easily
se
rve as a guide to students, dentists. and
orthodontists
alike.
Al
Ias
of
Orthodontics
is
an array
of
original photographs and drawin
gs
that high-
light the state.of-the-art modern practice of orthodontics with
fr
esh, new
id
eas
on

diagnos
is
, treatment planning, and, above all, therapy and
it
s clinic
al
applicatio
n.
It
provides the reader with a step-by
-s
tep decision-making approach to the prac
ti
ce
of
orthodonti
cs.
Th
e comprehensive yet easily readab
le
text and the
le
ge
nds that acc
om
-
pany the illustrations span the breadth
of
the referenc
es.

The clinician learns various
techniques from photographic material (in color) directly from the patient's mouth.
This atlas offers a
sy
stem that gives the best results while di
sc
losing invaluable tips
on
preventing clinical blunde
rs
that would lead to complications.
It
methodically explains
the reasons for
all
the clinical techniques used based on fundamental
bi
o
logi
c
al
and
biomechanic
al
principles, so that the reader will easily understand the orthodontic
thinking
pr
ocess. Furthermore,
it
will

give the practitioner the satisfaction
of
being
able to apply clinically all that
he
read
s.
While
refl
ecting the most current accepted
treatment methods, its structured outline and continuity pr
ov
ide all the information
in an easy, commonsense formal.
No
other book
in
the
field
of
orthodonti
cs
focu
se
s
on
the clinical side
of
da
y-

to-day practice with such an abundance
of
illustrations that
educate the reader on critical judgment
and
clinical modalities that give the best
treatment results.
It
is
an
invaluable educational source
of
the a
rt
and science
of
clinic
al
orthodontics for the graduate and undergraduate student, for the
ge
neral
dentist, and even for the most experienced orthodontis
t.
My sincere appreciation is addressed to the following individuals for their signi
fi
-
cant contributions to my education and academic endeavors
in
orthodonti
cs:

from
Ba
ylor College of Dentistry, Drs.
Ri
chard Cecn, Robert
Ga
ylord, Tom Matthew
s,
and
Peter Buschang, Rohit Sachdeva, Doug Cros
by
, Monte Collin
s,
Joe Jacobs,
Ri
chard
Aubrey, Moody
Al
exander, Wick
Al
exander,
Ed
Genecov, Larry Wolford,
Mr
. Stan
Ri
chardson, and Mr. Chris Semos; from the University
of
Minnesota, Dr
s.

William
Lilj
emark,
Ri
chard
Be
vis, Gerald Cavanaugh, T. Michael Speidel, Kev
in
Denis, Mark
Holmberg, James
Swift, Robert
Fei
g
al
, Robert Gorlin, William Do
ugla
s,
and the
former President of the Americ
an
Board of Orthodontics,
Ll
oyd Pearson;
fr
om the
U
ni
versity
of
Maryland, Dr. Dianne Rekow; from Tufts Uni vers

it
y, Drs. Nicholas
Darzenta and Anthi Tsamtsouris;
fr
om the University of North Carolina, Dr. William
vii
viii
• l'rtiaw
Pr
o
ffit
; from the University
of
Southern California.
Dr
. Peter Sinclair; from the
Univers
it
y of Iowa. Drs. John Casko and
Samir
Bi
shara; from the U
ni
vers
it
y
of
Athens, Drs. Meropi Spyropoulos, Paul Apostolopoulo
s,
and George Vouyouklakis;

from the Medical Co
ll
ege of Virginia,
Dr
. Robert Isaacson; and from Louisiana State
University,
Dr
. Jack Sheridan; and
fr
om the University
of
Toronto
, Dr. Angelo
Metaxa
s.
A spec
ial
acknowledgment is addressed to one man who is
an
inspiration to many
in
the
field
of
orthodonti
cs:
Dr
. T.M. Graber, Editor-in-Chief
of
the American Journal

of
Orthodontics 0
11(1
Denlofadal Orthopedics. I am deeply grateful to him for his
advice, recommendations, endless energy
and
enthus
ia
sm, and the wonderf
ul
support
th
at all my academic endeavors have enjoyed from him.
I
am
also grate
ful
to all the students with whom I have had the distinct pleasure
of
working, from the undergraduate
junior
dental class at the University
of
Minnesota
that presentcd me with the greatest honor
of
my academic life, the "Teacher
of
the
Year

Award" after
my
very first year in teaching, to the graduate students at the same
sc
hool and at Baylor College
of
Dentistry for their excellent wo
rk
on
all
the cases that
we treated together. Their critical thinking and quest for
kn
owled
ge
have certainly
influenced me and the way
I teach.
ANTttONY
D. VIAZIS, DDS,
MS
•
Contents
Part A
Preliminary Examination
of
the Patient
Chapter I C
hi
ef Complaint

3
Chapter 2
Dental Development
5
Chapter
3
Articulated Casts
7
Chapter 4
Radio
graphic Evaluation
13
Chapter
5
The
Te
mporomandibular
Joint
21
Chapter
6
Na
so
re
spiralary Function
27
Chapter 7 Oral Hygiene Considcrdtions
29
Chapter
8

Period
on
tal Pl
as
ti
c Surgery
35
Part B
Facial and Cephalometric Evaluation
Chapter I
Natura
l Head Position
41
Chapter
2
Bolton
and
Michigan
Standa
r
ds
45
Chapter
3
Cepha
l
ome
tric
Landmarks
47

Chapter 4
Soft-Tissue Evaluation
49
Chapter 5
Ant
eroposterior Skeletal Assessment
59
Chapter
6
Verti
cal Skeletal Assessment
67
Chapter 7 Cephalometric Dental Evaluation
73
Chapter
8
Poster
oan
terior Cephalometries
75
Part C
Growth
Chapter I
Growth
Co
nsiderations
79
ix
x •
Co

nl('lI/
.f
Chapter 2
Growth
Superimposition/Evalu
ation
89
Chapter J
Ha
nd-Wrist Radiograph Evaluation
97
Chapter 4 Nasal Growth
99
Part D
Orthodontic Mechanotherapy
Chapter J Biom
ec
hanics
of
T
oo
th
M
oveme
nt
105
Chapter 1
Orthodont
ic Metal Fixed Appliances 1
17

Chapter 3 Esthetic Brackets 1
21
Chapter
4 Direct Bonding of Bmckets/Adhesive
1
29
Systems
Chapter
5
Ba
sic
Orthodonti
c Instruments:
Wir
e
141
Bending
Chapter 6
Orthodontic
Wires
153
Chapter 7
Archfonns
163
Chapter 8
Co
il
Springs
16
7

Chapter
9
Elas
tometri
c Chain Modules
179
Chapter
10
Orthodontic
Elastics 1
89
Chapter
II
Class I Cuspid Relationship
1
99
Part E
Adjunctive Appliances
Chapter J
Rapid Maxillary Expansion (
RME)
205
Appliances
Chapter 1
Lip
Bumper
215
Chapter 3
Headgear 219
Chapter

4
Remo
vable Appliances
223
Chapter
5
Functional Appliances
227
Chapter
6
Chin-
Cu
p
Therapy
233
Chapter 7
Thumb-Su
cking a
nd
Hab
it
Co
nt
rol
235
Chapter 8
Protraction Faccmask
239
Chapter
9

Active Vertical Corrector
243
CO
n/enls • xi
Pari F Orthodontic Treatment Modalities
Chapter J
Ear
ly
Treatmcnt
249
Chapter
2
Tooth
Gui
da
nce (Serial
Ex
tracti
on)
261
Chapter
J
Tooth
Recont
ouring
265
,
,
Chapter
$ T

reatmen
t
Planning
in thc P
ermancnt·
271
Dentition
Chapter 5 Incisor
EX
lnlc
tion
/ Missing Incisor/ 307
Second
Molar
Ex
tra
c
ti
on
Th
cnlPY
Chapter
6
Intru
si
on
Mechanics/
Co
mprom
ised

323
Periodo
ntium
Thcmp
y
Chapter
7 Retention
331
Indu
343
C"
e r
Chief
Complaint
The
examination
or
the patient in the o
ffi
ce sho
uld
always st
an
with the medical
hi
story, as is
done
in
any dental
offiCC.

I
-
3
The dental clinical
ev
aluation should follow, where
ge
ne
ral
notes, as
well
as an evaluation
of
the intraoral so
ft
t
iss
ue, teeth, and oral
function, and panoramic
radiograph are made.
2
•
1
Any operati
ve
, periodontaL and
e
nd
odo
nti

c work
(i
f needed) should
be
completed before initiation
of
on
hodontic
treatment, whereas any tcmporomandibular joint
(T
MJ
) pain or d
ys
func
ti
on should
be
addressed before the onset
of
on
hodon
ti
c treatment (Table A
1.1).
Permanent
pr
os
the
ti
c work should

be
done afterward.
Inquiring about the patient's c
hi
ef
complaint, i.e the reason he or she seeks
orthodontic treatment, is
of
utmost importance. The c
hi
ef
co
mplaint must have been
met by the end of treatment, otherwi
se
the patient
will
not
be
happy, even if the
orthodontic therapy is of the highest standard
s.
If the pati
en
t
or
guardian has unrea
lis
-
ti

c expectations that may not
be
met with treatment, the
cl
i
ni
cian ought to educate
him or her so that he or she understands the limitations of the
va
ri
ous therapeu
ti
c
modalities
in
modern orthodontics. A good
ex
ample
is
the chan
ge
of
the so
ft
ti
ss
ue
(lip
s)
as a result

of
ex
trac
ti
on therapy. A patient
will
not
be
satis
fi
cd
if.
after 2 years of
orthodontics, he
or
she has a beautiful occlusion accompanied by late nasal growth
that makes the lips appear more
retrusive.· In addition, the l
ow
degree
of
predictab
il
ity
associated with the upper lip
in
rcspon
se
to orthodontic tooth movemcnt, possibly
cau

se
d by the complex anatomy or dynami
cs
of
the upper lip, I might cau
se
undesir-
able chan
ges
in
the soft-
ti
ss
ue profile
in
crowded ca
se
s that invol
vc
extractions
of
pe
rmanent teeth. Nononhodontic measures
(i
.e rhinoplasty or genioplasty) shou
ld
be
discussed with the patient before the stan
of
the orthodontic treatment. I

4 •
Pan
A
Pr
eliminary
EXa
mi
nOl
ian
of/
he
Par
ie
ni
Table 1.1
Cl
ini
cu
l Information Form (DenIal)
General Information
Parent name Guardian name
Ad
dress
P'Jti
e
nt
name
Goad<
Hobbies
Do

"
Telephone
C
hi
ef
complaint
Pa
ti
ent h
ei
ght Father's height Mother's height
•
Patient mot
iv
ation
Prepubenal Cireumpubenal Postpubenal
Ha
bit
s
Fa
mil
y
hi
sto
ry
of
ma
loc
clusion
Intraoral Soft Tissue Evaluation

-
Pa
th
o
logy
Oral hygiene Attached gingiva
Gingiv
al
re
ce
ssi
on
Attachment Pocket depth > 3mm
Frenum
Intraoral DenIal Evaluation
and
Panoramic
Radiograph
""
.,
Extracted
Root
le
n
gth
Uy
poc;a
lc
ilication Fractured
CW"

i11
Crown
jb
rid
gc
Missing Fractured root
Supernumera
ry
Impacted
Stained
Wisd
om t
eet
h
Ankylosed Endodontically treated
Bo
ne
pathology
Unerup
ted
Condylar o
utline:
Al
veo
la
r
bo
ne
F
ne"

•
IOna
I Eval ation
•
Speech pathology Musc
le
tenderness
I
nt
ernal dernngement
Br
eathing Clenching
S
tag
e I (early or late c
li
ckin
g)
Swall
o
win
g Bruxism
Stage
II
(morning l
oc
k)
Tongue size Deviation upon opening
Stage
III

(acu
te
l
oc
k)
lip
tonicity Deviation upon closing
Stage
IV
(f
un
ction o
ff
d
is
k)
Ton
si
l s
ize
Range
of
motion (ROM)
Stage V
(pain, grating sound)
CO/CR
di
screpan
cy
TMJ pain

TMJ d
ys
fuOCI
ion
References
I. Tal
ass
MF, Tallas L, and Baker RC:
Soft
tissue
pr
o
file
chan
ges
resulting from retraction of max
il
la
ry
inci
so
rs
.
Am
J Onhod Dc:qtofacial
Onho
p 9 1 :
38
5-39
4, t987.

2. Proffit
WR
, and White
RP,
J
r.
: Surgical·Orthodontic Treatment.
St
. Lou
is.
MO
: M
osby
Year
Book
.
199
1.
3.
Proffit WR:
Co
ntem{IQraryOrrhodolUi
cJ.
SI.
Louis, MO:
C.
V. M
os
by Co

19
86
.
4.
Bu
sc
hang
PH
,
Via
z
is
AD, DelaCruz R, a
nd
Oakes C: Hori
zo
ntal gro
wth
of
the
soft·ti
ss
ue
n
ose
re
lative
to maxillary growth.
Jain
Orthod

26
:
111
-
11
8,
1
992
.
I
ella
Dental
Development
The development
of
teeth begins
in
utero,
but
it is not until 2 to 3 years
of
age that all
deciduous teeth appear in the toddler's
mouth
,I.2
The
most common sequence
of
eruption starts with the lower central incisors, followed
by

the upper centrals
in
the
first 6
months
of
life; the upper lateral
and
low
er
in
cisors crupt by the
end
of
the first
year
of
age; the upper and lower first deciduous molars, followed by the cuspids,
appear by
18
month
s,
a
nd
the lower and upper second deciduous molars erupt by the
cnd
of
the second
yea
r or as late as the third

yea
r
of
life 1
):
(see
Fig.
FI.l
S).
Pa
st this
point, very little
in
crease
in
dental arch width occurs. Spacing is desirable
in
the
primary dentition; lack of spacing means large teeth or small arches and is s
tr
o
ngl
y
suggestive
of
crowd
in
g
in
the permanent

dent
ition.
Th
e eruption
of
the permanent dentition starts around the age of 5
or
6 years
wi
th
the first
permanent
molars distal to the second deciduous molar tceth.l
.2
The periods 5
to 8 years
of
age
and
9 to
12
years
of
age are called ea
rl
y and late mixed dentition
stages, respectively. Around 6.5 years
of
age, the lower central incisors erupl, followed
by the upper centrals by 7 years

of
age. 1
,2
The
lower laterals erupt by age 7.5 years,
followed
by their maxillary counterparts
at
age 8 years
or
as late as 9
ye
ars
of
age
l
.
l
(see Fig.
F1.I6)
. At
appro
ximately
10
years
of
age, the lower permanent cuspids
mak
e
their appearance in the child

's
mouth
, followed by the upper first
bi
cusp
id
s at age
10
.5
years and the lower first bicuspids
at
age
II
years.1,2
The
upper and lower second
bicuspids erupt very close to each
other
at
a
ge
11
.5 years, followed by maxillary
cuspids and the second
permanent molars by the age
of
12
ye
ars
or

as late as age 13
years.
l
,2
One
mu
st keep
in
mind
that there is one significant variation
of
t
oo
th
eruption in the population: teeth
may
erupt
as early or as late as 2 years in relation to
the average ages mentioned above and still
be cons
id
er
ed normaL
Teeth usually erupt when the roots arc
one
half to
thr
ee
quart
ers formed.

2
Aft
er
the
end
of
the early mixed dentition stage, the upper
in
cisors may have substanti
al
spac
in
g
as their crowns are inclined toward the distal. This is called the
"ugly
du
cking stage"
and
is
considered a
nonnal
co
ndition that will sclf-correct later on; it happens
du
e to
the eruption path
of
the
permanent
cuspids as they

co
me into position for eruption
along the roots
of
the lateral incisors (Fig. A2.
1)
.
Th
e sum
of
the mesiodistal width
of
the deciduous cusp
id
and
molar
teeth is 1
.3
and
3.1
mm
greater than the permanent cuspid and bicuspid tccth in the maxilla and
the mandible, respectively (leeway space).2 This space
is
ge
nerally used
in
the
perma
~

nent dentition to permit improvement
of
possible crowding of anterior teeth and
al
so
to allow a slight mesial migration
of
the first
permanent
mandibular molar into a solid
class
I occlusion.
2
.)
The
le
eway space may
be
quickly lost
fr
om
prematur
e exfoliation
of
teeth
and
quick m
es
ial
mo

ve
ment
of
the permanent molar to an extent that the
lower second
bi
cuspid
ma
y
be
blocked
out
toward the ling
uaJ2
(see Fig.
06
.7).
It
should be noted that the last increase in dental arch width occurs as the permanent
cuspid teeth e
rupt
into their position in the arch. Expansion
of
the arches in this area
is
qu
estionable past this stage.
•
6 • ParI A Preliminary t.:ramillation
of/

he Paticrll
A2
.1
F
ig
ur
e
A2
.1 The "
ugly
duckling" stage
of
tooth development.
In a study on the changes in the molar relation between the deciduous and perma-
nent
dentition
s,
it was concluded that 6
1.
6%
, 34.3%, and 4. I %
of
patients end up
wi
th
a class I, class
II
, and cla
ss
III

permanent molar relationship, res
pe
ctivel
y.]
Patients
who start
wi
th a
full
distal step in the deciduous dentition develop into a class
II
molar relationship; thus, treatment shou
ld
be
initiated in these cases as early as
possible. Conversely, almost half
(5
0%
) of patients who ha
ve
a
50%
class
II
primary
mol
ar
relation (end-to-cnd
flu
sh plan

e)
develop a cla
ss
I pe:nnanent molar occlusion,)
Close observation
of
the
se
patients
is
nceded until a cla
ss
I relation occu
rs,
References
I.
M
oh
l NO, Zarb GA. Carl
sso
n GE, a
nd
Ru
gh
JO: A Textbook
of
Occlusiol!.
Ch
ica
go:

Quintessence
Publishing.
1988.
2.
Undergraduate
sy
llabu
s.
University
of
Minnesota, Depanment
of
On hod on ti
cs.
Minneapoli
s,
M
N.
1989.
3.
Bi
shura
SE,
Hoppens
BJ
,
Ja
cobsen JR. and Kohout Fl . Chang
es
in

the molar relationship between the
deciduous and pennane
nt
denti
ti
on: A l
ongi
tu
din
al
s
tu
dy
. Am J Onhod Dentoracial Onhop 93:19 - 28.
1988 .
\
ell
Articulated
Casts
The most supero-anlcrior position
of
the
co
ndyle is musculoskclctally the most stable position
of
the
joint
(centric relation)
,I
-l In this position, the co

nd
yles arc resting against the
posterior slopes
of
the articular eminences with the articul
ar
disks properly interposed
and all
of
the muscles that coordinate joint movement at rest.
I
-
1
During r
es
t and
function, this position is both anatomically and ph
ys
iologica
ll
y sound. A posterior
force
10 the mandible
can
displace the condyle
10
an unstable posterior (or retruded)
position.
Be
cause the rctrodiscal tissues arc highly vascularized, well supplied with

sensory nerve fibers, and not structured to accept forces, there
is
great potential for
eliciting pain or causing breakdown,
l.3
The
position
of
the mandible where the relation
of
opposing teeth provides f
or
maximum
occlusal intercuspation is called centric
ocdusion.
I
-
4
Thi
s,
idea
ll
y,
should
coin
ci
de with centric relation
4
;
this

is
what the clinician should strive for during
orthodo
ntic treatment. In most cases, a slight discrepancy
of
about I
mm
also can be
acceptabl
e,
where the position
of
the mandible in centric relation
is
slightly behind
it
s
position
in
centric occ
lu
sion.
In
contrast to craniometric variables, which have
hi
gh heritabilities, almost all
of
the occlusal variability is acquired rather than inherited.
5
Thus, a careful examination

of
the patient's malocclusion
is
essential. This is best done from a set
of
articulated
casts
in
centric relation (CR) (Fig.
A3.
I).
The following wax bite
registration technique is suggested for proper recording
of
the patient's bit
c':
the right
thumb
is placed
on
top
of
the patient's chin with the right
index finger
und
er the patient's left gonial angle and the right second fmger
under
the
patient's right gonial angle (Fig. A3.2).
Th

e mandible is allowed to close (Fig.
A3
.3)
in
such a
manner
that the lower incisors
conta
ct the anterior wax. until a
2-
mm
posterior
opening in the molar area is obtained (Fig. A3.4). When the patjent squeezes. the
mu
sc
le contractions scat thc
co
ndyles
in
a superior and slightly anterior position
against the eminen
ce.'
Th
e objective is to gain an index
of
both maxillary and
mandibular incisal edges without making any tooth contact
s.
The anterior wax is
cooled down and removed while a soft posterior

wax
is
placed against the maxillary
posterior teeth (first molar and second premolar area) (Fig. A3.5). The hard anterior
wax is secured
in
the anterior region (Fig. A3.6) and the mandible is gently manipu-
lated into centric relation as described
atxlVc
(Fig. A3.7). After the mandibular closurc
has been stopped by the limit
of
the index
es
in
the anterior section (Fig. A3.8), both
picces
of
wax are removed aftcr they are cooled down with air-spray (Fig. A3.9). A
centric occlusion wax bite is also taken as the patient opens widely and bites
all
the
way
through the wax until the teeth touch
full
y.
8 •
rart
A
PT("iminary

ExaminatiQn
of
rile
Patient
A
3.
1
Figure
"'3.1 Articulated casts
on
SA
M 2 (Great Lakes,
NY)
articulator. Only by
mounting
the casts are we a
bl
e to
notice
any
prematurities,
fu
ncti
ona
l shifts,
and
the exact
relationship of teeth in centric relation. Hand-articulating
polished casts ca
nnot

capture init
ial
tooth contacts.
A3
.3
Figure
A3
.3
The
patient's mandible is allowed to close gentl
y.
A3
.2
F"tgUre
A3
.2 H
and
manipulation for recording centric rela-
tion (CR) positio
n:
the clinician's right
thumb
is
placed
on
top of the patient's chin,
th
e right index finger under the
pati
ent's

le
ft
gonial angle,
and
the right second
fin
ger under
the
patient's righ t gonial angle.
A3
.4
Figure
"'3.4
The
closing motion is stopped when the lower
incisors
come
in contact with the
ant
erior wax. Note the
bile opening in the bicuspid/m
olar
area.
No
posterior teeth
are allowed to contact.
AJ.5
Agu.
•
agau

''''
inta
.pp
dibl
A3
.5
Flgur.
A3
.5
A soft poste
ri
or piece
of
wax
is pressed lightly
against
the posterior teeth.
rtgure
Al
.7
The mandible is again very gently manipulated
into
CR. Note that
th
e anterior wax
is
held against the
upper
a
nt

erior teeth during the closing motion of
th
e man-
dible.
Cbapler
3
Ani
c
lll(l/M
CaslJ
. 9
A3
.6
Flgur.
A3.6
While gently holding the posterior wax in place.
the ha
rd
anterior
wax
is
secured in its pos
iti
on. Note the
indentations of the lower incisors recorded previously.
Figure
A3.8
Th
e mandibular closing motion is stopped as
soon as the lower anterior tee

th
come in contact with the
ha
rd
anterior wax. The posterior teeth made their cusp
indentations in the posterior
wax
, without even coming in
co
ntact with
th
eir
co
unterparts.
Th
is
wa
y,
the muscles ha
ve
gu
ided and seated the
co
ndyles in the most supero-anteri
or
pos
it
ion against the eminence.
10
•

Pllrt
A Preliminary Examination
o/llw
Patient
A3
.9
Figure
A
3.9
The
wax
pieces
are
cooled
down
with
air-spray
before
they
are
removed from
the
mouth.
Once mountcd
on
the articulator, the dental casts are used to evaluate the following
7
:
Angle
Classification

A class I mol
ar
relation exists when the
me
siobuccal cusp tip
of
the upper fust molar
occludes in the buccal groove
of
the lower first molar (sec Fig. E3.7). Similarly, a class
I cuspid relation exists when the upper cuspid occludes in the embrasure between the
lower first bicuspid and the lower cusp
id
(see Fig. F4.72). A full cusp width ahead
of
the class I position
is
d
efi
ned as a full-step class
II
(see Figs. F4.84, F4.92, F4.96). A
full cusp width back
of
the class I position is a
full
class
III
(see Fig.
CI.I5).

An
end-to-end relation
is
termed as a
50%
class
II
(see Fig. 0 11.1)
or
50% class
III
(see
Fig.
09.33)
, depending
on
the direction
of
discrepancy.
Overbite
The
vertical overl
ap
of
teeth
is
the overbite
(0
8
).

The
08
in the
in
cisor area shou
ld
be
approximately 2
mm
(see Fig. C
I.I8
).
Overjet
The
horizontal overlap
of
teeth
is
the overjet (O
J)
. The OJ in the incisor area should
be
1 to 2
mm
(see Fig. C I.I8).
Crowding
The best and most accurate way to evaluate the existing arch length discrepancy
is
by
measuring the width

of
all
the teeth in the arch with a campus, as
well
as measuring
the actual arch length
.'
A clinical way to assess crowd
in
g
is
by
"eyeballing" it, taking
into consideration the average width
of
various major teeth
(bicuspids-
7
mm
;
cuspids
-8
mm; lower incisors
-6
mm
; upper centrals -
IO
mm).
By
subtracting

how much tooth material
is
blocked out
of
the arch or
is
in a crowded position, one
may very quickly evaluale the space that is needed to obtain good tooth alignment.
This
is
undoubtedly a very crude method, but one that clinical experience has shown
to approximate
(+
1 mm) to the exact discrepancy (sec Figs.
06.6
, D6.7, D9.18,
09
.
19
,
F4
.62. F4.63,
F5
.3, F5.4.
F5
.
11,
F5.12, F5.24,
F5
.25). The cause

of
crowding
FI
"
i
C'Iulpltr J A
f//C
II
/OIN
Costs •
11
may differ from
one
subject to
another
.
or
there may
be
morc than
one
fa
ctor
contributing to the development
of
crowding
in
any
onc
individual. B

Crossbite
Crossbilc occurs when
on
e or morc teeth arc
in
an abnonnal buccolingual
re
lation-
ship.?
Single-tooth crossbit
cs
arc usually dental
in
nature (see
Fi
gs.
E4
.1,
E4
.2
).
Multiple-tooth crossbitcs
ar
e anterior (sec Fig. C 1.I3)
or
poste
ri
or (sec Figs. e
1.1
3.

C
1.
26, C1.30)
and
usually skeletal
in
nature
.?
Anterior looth crossbites may
be
"pseudo class
III
" (due to a shift) (see
Fi
gs.
F1.I6, F1.I 7) or "true class
III
" (true
skeletal) (see Fig. C1.13)
,7
Posterior cro
ss
bitcs arc unilateral or bilateraL Unilateral,
multiple-tooth crossbites arc usually the result
of
a side shift to
one
side from a
bi
lateral skeletal crossbit

e.
T he vast majority
of
multiple-tooth cro
ss
bites are bilateral
and are due to a constricted maxilla (see Fig.
F4.I05). Multiple-tooth cro
ss
bil
es
should
be
corrected as soon as possible
(t
he youngest known patient is 3 years old) to
avoid the possible development
of
a skeletal malocclusion
or
abnormal eruption
of
teeth, as
well
as
to improve the patient's esthetics
9
(sec
Figs.
F1.l2

through FI.1 5
).
Dental
Midlines
The facial midline (see
Fi
g.
B
l.l
) (middle
of
eyebrow
s,
tip
of
the no
se
, cupid's bow)
should coincide with the upper dental midline (between the upper centrals) and the
lower dental midline (between the lower centrals) (sec Fig.
09
.27).
If
a co
mp
romi
se
must be
mad
e due to the patient's malocclusion, it

ma
y be best to leave the lower
midline off by
I to 2
mm
(a lot
of
patients
do
not show their lower tccth upon
smi
lin
g)
. T he upper denial midline should co
in
cide with the
fa
c
ial
midline for
an
esthetically pleasing smile (see
Fig
. A8.3).
Tooth-Size
Discrepancy
A3.10
A tooth-size discrepancy (TSO) exists when the size
of
the lower or the upper tccth

is
not in proportion with th
at
of
their counterpan
s.
IO
-
12
An
ano
maly
in
the size
of
the
upper lateral incisors is the most co
mm
on cause, but variations in
bi
cuspids or other
tccth
ma
y
be
prescnt
7
(see Figs.
A3.1O
, F3.7,

F5
.22). In such a case, it would
be
impossible to obtain an ideal OB/OJ relation
of
2 mm when the cuspids are in a cla
ss
FIgU
re
A,3
.
10
Small upper left lateral. Spaces were le
ft
next
\0 i\ for prosthetic
work
.
12 • '
>art
A
Pr
eliminary Examination
of
till!
Pa
tient
I occlusion. If there
is
excess maxillary tooth material,

we
will
en
d up with an
excessi
ve
OJ (sec Fig. FS.8); if the excess is in the mandibular arch, then minimal
OB/OJ w
ill
exist
and
the cuspids will occ
lu
de in a slight class
III
relation.
A large percentage
of
patients have mesia
l-dist
al tooth-size di
sc
repancies, approxi-
mately 13.8% and 9.2% for the mandibular and maxillary dentitions, respectivel
y.
I I
Su
ch
di
sc

repancies, if left untreated, could lead to future posttreatment relapse, espe-
cia
ll
y in the mandibular incisor area. Interproximal reduction
wi
ll
, in most cases,
a
ll
eviate such discrepancies.
A method used to assess TSD is Bollon's
analysis.
1
,ll
If alterations
of
tooth s
iz
e are
to
be done
in
the upper arc
h,
the sum
of
the width
of
the lower anterior teeth
is

multiplied by 1
.3
to gi
ve
the di mensions of the ideal upper arch for these partic
ul
ar
lower anteriors.
IO
If a
lt
eratio
ns
of
tooth size are to
be
done in the lower arch, then the
width
of
the upper anterior teeth is multip
li
ed by .775 to
gi
ve
the ideal lower arch.
1O
If the TSD is in the posterior teeth, then th
ey
may
be

se
lectively reduced in width,
enough to obt
ai
n a class I cuspid
re
lation (see
Figs
. F3.7,
F3
.8). Interproximal reduc-
tion should
be
done in the upper or lower arch in order to make these teeth
fit
in
relation to their counterparts.
References
I.
Okeson
IP
: M
anagement
of
Te
mporomandibular
D
iso
rder
s a

nd
Occ/usion,
2nd ed. St.
Lo
uis. M
O:
C.V.
Mosby
Co

1989.
2.
Mol
al
NO
, urb GA, Ca
rl
sson GE, and Rugh S
O:
A Texlbook
of
Occ/usiOll
. Chicago: Quintessence
Publishi
ng,
1988.
3.
Americ
an
Academy

of
Craniomandibular Disorders: C
ran
iomandibufar
{Jis
o
rdcrs
: G
uideline
s
fo
r
£~af

uoti
on,
Diagn
os
is
and
Manag
e
ment.
McNeill C, ed. Chicag
o:
Quintessence Publishing, 1990.
4.
Pa
rker WS: Centric relation and centric occlusion -
An

orthodontic responsibility. Am J Orthod
Dentofacial Orthop 74:481
-5
00
,
19
78.
5. Harris EF,
and
Johnson MG: Heritability
of
craniometric and occlusal variables: A longitudinal sib
an
al
y
si
s.
Am J Orthod Dent
of
acial Orthop 99
:258-2
6g, 1
991
.
6.
Carlson G: Advances
in
Orthodont
ics:
Seminar Series (Course Syllabus). Minneapoli

s.
M
N.
1988.
7. Proffit WR:
Co
ntemporary
Orlhodonlic
s.
St. Louis, MO: C. V. Mosby Co.,
198
6.
8. Richardson ME: The role
of
the third molar in the cau
se
of late lower arch crowding: A
re
view
. Am J
Orthod Dcnt
of
acial Orthop 95:79- 83.
1989
.
9. Vadiakas G, and Viazis
AD
: Anterior crossbite
co
nnection in the prima

ry
dentition. Am J Orthod
Dent
of
acial Orthop 102: 160- 16
2,
1992.
10. Wolford
LM
: Surgical-
on
hodontic oom:ction
of
dentofacial and craniofac
ia
l deformiti
es-Sy
llabu
s.
Baylor Col
lege
of
Dentistry, Dallas.
TX
, 1990.
II.
Crosby DR. and
Al
exander RG:
Th

e occurrence
of
tooth size discrepancies among different malocclu-
sion groups. Am J Orthod Dentofacial Orthop 95:457 - 461, 1989.
12.
Bolton
WA
:
The
clinical application
of
tooth
si
ze analysis. Am J Orthod Dcntofacial Orth
op
4
8:5
04-
529,1962.
Ii
,
ella
ler
J
Radiographic
Evaluation
A careful dental and rndiographic
(p
anoramic
or

pe
ri
apical) evaluation may re
ve
al
a number
of
si
tuations that need to
be
addressed before the initiation
of
orthodontic mechano-
therapy.
An
kylosis
Ankylosis,' a localized fusion
of
alveolar bone and cementum, is the result
of
a
defective
or
discontinuous periodontal membrane and is apparently caused by me-
chanic
al,
the
rm
al,
or

metabolic trauma to the periodontal membrane during or after
tooth eruption.
It occurs most
of
ten
in
the prima
ry
dentition
(se
e
Fig
.
010
.8) in the
mandibular teeth, and in molars.
It
can sometimes be detected
fr
om radiographic
ev
id
ence
of
periodontal membrane obliteration or by a sha
rp
or ringing sound upon
percu
ss
ion and

by
la
ck
of
tooth mobility or sorene
ss,
even
wi
th hea
vy,
continuous
orthodontic
forces.
'
In
the primary dentition, ankyl
os
is
is
usually treated by simple neglect, restoration,
or
ex
traction.
l
Ankylosis
of
a permanent tooth, ho
wev
er, is more complicated
if

orthodontic treatment is planned. Intervention can
in
clude luxation, corticotom
y,
or
ostectomy. I
M
os
t infra-occluded and ankyloscd primary molars with a permanent successor
exfoliate norma
ll
y.2
The decreased height of the alveolar bone level at the
si
te
of
the
infra-occluded
primary molar has been reponed to normali
ze
after the eruption of the
permanent successo
r.
Infra-occlusion and ankylos
is
of primary molars docs not co
n-
stitute a general
risk
of

future alv
eo
lar bone loss
me
sial to the
fi
rs
t permanent molars.
Primary
Failure
of
Eruption
Primary failure
of
eruption describes a
co
ndition
in
which nonankylosed, usually
posterior teeth
fail
to erupt, either
full
y
or
partiall
y,
becau
se
of

fai
lure
of
the eruption
mecha
ni
sm.
l
-
S
The teeth most commonly involved are the deciduous and permanent
molars, although premolars and cuspids may also
be
affected
.$
There appears to
be
no
mechanical impediment to eruption
in
these cases.' Unilateral situations occur more
frequently than bilateral ones. A posterior open bite, caused by a primary failure
of
eruption,
will
not respond to orthodontic treatment; a segmental alveolar osteotomy
offers the only possible treatment modality.
Dias
temas
Midline diastemas arc quite common among ind

iv
iduals (see
Fi
g.
F4.11). Closing
them
poses no problem orthodontically, but in many patients th
ey
lend to re-open,
especially
if
cau
se
d
by
an abnormal labial
fr
cnum.
6
14
•
Part
A
I'fI
'fimi
nar
y Examination
oj
lhe Path'nl
•

It
is
important
to
close the space
ort
hodontica
ll
y as
soon
as possible
and
then
perform the s
ur
gical procedure
of
ab
nonnal
labial frenum, thus allowing healing
of
the tissues
to
occ
ur
with
the
teeth in their newly established positions.
6
It

is
suggested
that
when
the fr
en
um
is wide and attached below the mucogingival j
un
cti
on
in
ker'J.
tinjzed tissue,
it
often will regenerate after frenectomy.' To prevent this from
occurring, epithelial graft from
th
e palate is placed
over
the
area
on
removal
of
the
frenum, preventing
it
s ingrowth.
'

Root
Re
s
orption
R
oot
resorption occurs in every patient
who
undergoes
orthodonti
c
treatment.
In the
majority
of
cases, it is a mere
blunting
of
the r
oot
apices. In some pa
ti
e
nt
s,
it
is more
severe for reasons that seem
to
be

idiopathic. with
the
exception
of
previou
sl
y trau-
m
at
ized t
ee
th, which are m
ore
susceptible to resorption a
nd
loss of vitality
(F
i
g.
A4.1
).'
Around
16.5%
of
patients have approx
imat
ely I
mm
of
resorpti

on
of the
maxillary incisor teeth.' Maxilla
ry
incisors have been reported to
be
the most susce
p-
tible
to th
is severe resorpti
on
, with
other
teeth less affected. A recent study showed
th
at
3%
of
patients
have severe resorption (greater than
one
quart
er
of
th
e root
length)
of
bo

th
maxillary
cent
ral incisors (Fig. A4.2).
Less
re
sorption
is
observed in patients
tr
eated before age
II
year
s,
perhaps
due
to
a
preventive effect of the thick layer
of
pred
ent
in
on
young, undeveloped rool
s.
9
C
on-
ta

ct of
ma
xi
ll
ary
incisors with the lingual
co
rtical plate may
pr
edispose
to
resorption
.'
Class
III
patients
ar
e overrepresented in
the
group
with severe resorption.'
Figu
re A4.1 Trauma to these central
in
c
isors
from
a
bicycle
accident led to their severe root resorption

and
loss of
vitality.
FI~
of
roo
,
A4
,2
Figure
A4.2
Resorption of central incisor teeth after 2 years
of orthodontic
treatment.
One
quarter
to
one
third of these
r
oolS
have been lost.
Chapter 4 Radiographic EI'afliation •
15
•
The
longer the active treatment time, the greater the chance
of
severe resorption.
Obviously, a patient with small, rounded roots

is not a good can
di
date f
or
excessive
t
oo
th movement. Iatrogenic root resorpti
on
is caused
by
ji
gg
ling teeth over long
periods
of
time, indecisive treatment that causes changes in the direction
of
tooth
movement,
and
proximating
of
the cortic
al
plate.
1O
No relation
ha
s been found

between the
amount
of
root shortening and degree
of
intrusion achieved,
!1
In general,
tr
eatment time is the most significant
fa
ctor for occurrence
of
root shortening. In a
re
cent long-te
nn
evaluation
of
root resorption occurring during orthodontic
tr
ea
t-
ment, it was shown that there are no apparent changes after appliance removal except
remodeling of rough and sharp edges.!2
Impacted
Cuspids
Impac
ti
on

of
the cuspid tccth
ll
-
20
is caused primarily
by
the rale
of
root resorp
ti
on
of
the deciduous tccth, disturbances
in
tooth eruption. tooth size/arch length di
sc
repan-
cies, rotation
or
trauma
of
tooth buds, pre
matur
e r
OO
I closure, ankylosis, cys
ti
c
or

neoplas
ti
c f
or
mation, clefts, and idiopathic causes. Most of the impac
ti
ons arc unilat-
eral and on the palatal side.
16
The evidence
of
maxillary impaction ran
ges
from 0.92%
to 2.
2%
; maxi
ll
ary impaction is twice as co
mm
on in females than
in
male
s,
I6 The
in
ci
dence
of
mandibular impaction is much less, 0.

35%,16
Impacted cusp
id
s
ma
y
cau
se
resorption
of
the adjacent incisor teeth; thus, their extraction
or
uncovering and
movement into thc dental arch is necessary (Fig. A4.3).
Potential incisor resorption
cases from impacted cuspids are those
in
which the cusp
id
cusp in periapic
al
and
panoramic films is positioned medially to the midline of the lateral incisor
(0.
71
%).!6
The
ri
sk
of resorption also increases with a more mesial ho

ri
zontal path of eruption.
2
!
16
• J'a
rt
" P
rrii
m
mar}
' Exami
nal
ioll
of/h
I' I'miml
M.3
Figure
A4
.3 An impacted cuspid has caused almost complete
resorption
of
the lateral incisor tooth
and
signific
ant
de-
struction of the central incisor tooth.
Surgical uncovering
of

these teeth
is
the standard treatment procedure, followed by
direct bonding of an orthodon
ti
c bracket onto the tooth and mechanical traction with
elas
ti
cs
or
springs to bring the teeth into the arch (see Fig.
F4
.58).
An
a
pi
cally
repositioned nap f
or
la
bially situated cusp
id
s
is
recommended.
I.
Adequate attached
gingiva need
be present (or s
urgi

cally p
la
ced) to avoid mucogingi
val
problems. Wire
ligation
("lasso" type)
in
stead
of
direct bracket placement
onto
the uncovered tooth
is
prohibited because it leads to lo
ss
of
attachment and to external root resorption and
ankylosisY In addition, any surgical exposure beyond the cement- enamel
jun
c
ti
on
leads to bone loss.
Treatment
of
cases with impacted cusp
id
s is quite lengthy, depending on the
position a

nd
or
ientation
of
the impacted tooth
in
the bone.
'6
•
'7
It may take between
12 and
30 month
s.
Also, at the end
of
treatment, the
se
t
ee
th
will
show the presence
of
a
5-
to
7-
mm pocket, usually on the distal sid
e.

They display significa ntl y more loss
of
periodontal support on the buccal
and
palatal surfaces than
do
normal teeth.
11
Excellent oral hygiene
wi
ll
preserve these teeth throughout life without further sequelae.
An
a
lt
ernative to surgical uncovering and
len
gthy orthodontic treatment of im-
pacted teeth
is
the autotransplantation
of
these teeth. Autotransplantation shou
ld
be
performed at a sta
ge
when optimal root development
of
the transplant may

be
expected; namely, one half to
thr
ee quarters
of
the
full
root length.
I'
When transplan-
tation
is
pe
r
fo
rmed at an ea
rli
er stage
of
root developme
nt
, the final root length may
be
shorter than desirabl
e.
If autotransplantation
is
performed at a later sta
ge
of

root
development. the
ri
sk
of
root
re
sorption increases. The surgical procedure should be
as atraumatic as possible and requires a surgeon
well
acquainted with the method.
Teeth transplanted with
in
complete and
co
mplete root f
or
mation show
96%
and
1
5%
pulp heali
ng,
respcctively.'9
Th
e size
of
the apical foramen and possibly the
avoidance

of
ba
cterial contamination during the surgical procedure are explanatory
factors for pulpal healin
g.
Trauma to the periodontal ligament (PDL) of the trans-
plant
is
the
ex
planatory factor for the development
of
root rcsorption.
'9
.'"
in
&!
cu.
Cliapll'r 4 Radiographic f :l'ulliulion •
17
A rairly new technique, transalveolar transplantation, is used to remove la
rge
am
ou
nts or bone with a
bur
except ror a thin la
ye
r close to the root surfa
ce.20

This
bone is then very gently removed with an elev
at
or
to avoid
damag
e to the cementum.
Th
e tooth is stored in the socket throughout the operative procedur
e.
Finall
y.
the
cuspid is moved through the alveolar
pr
ocess into
it
s determined
po
sition. A sec
ti
ona
l
arch wire is u
se
d to stab
ili
ze but not immobilize the transplanted cuspid. Sometim
es
,

grinding
or
the antagonist tooth
is
required to avoid traumatic occlusion. A postope
r-
ative orthod
ont
ic appliance check
is
perrormed I week later, when the sutur
es
are
removed. Furth
er
orthodontic controls are performed every 2 weeks ror 6 to 8 week
s.
Tooth
Transpositions
A4.4
Tran
sposition has been described as
an
interchange
in
the position or
tw
o permanent
teeth within the same
quadrant

or
the dental arch.22-n The maxillary permanent
cuspid is the tooth
mo
st rrequently involved
in
tr
ansposition with the first bicu
s-
pid
.22,2
~
less orten with the lateral incisor (Fig. A4.4)
.12·2
4 The retained deciduous
cuspid may be the primary cause for deviation of the permanent cus
pi
d from its
normal path of eruption.
If the mandibular cuspid
and
lateral
in
cisor have already erupted in their trans-
posed position, correc
ti
on
to their
nonnal
position should usually

no
t
be
attempted.
22
Al
ig
nm
ent in their transposed position
wi
th reshaping
of
their incisal surraces will n
01
damage the tccth or supporting structures and w
ill
present an acceptable esthetic
result. If
one
or
the transposed
or
adjacent teeth is severely affected by caries or
trauma
or
if
there is a severe lack
or
s
pa

ce,
ex
traction
of
that t
oo
th should be
cons
id
ered
.2
2
•
23
Ir t
oo
th movement is undertaken to correct the transpos
iti
on, in
or
der
to avoid root inte
rf
erence or resorption during treatment and to prevent bony loss at
the cortic
al
plate
of
the labially positioned cusp
id

, the transposed tooth
(premo
lar or
lateral incisor) sh
ou
ld
first
be
moved palatall
y,
enough to allow ror a
fr
ce movement
of
the cuspid to
it
s
norma
l place.
22
.23 This last method is the least desirable treatment
of
choice.
Figure
AU
Transposed maxillary right cuspid. as
it
is erupt-
ing
dis

tal
to the first bicuspid. Note
th
e retained primary
cuspKl
.
18
• Part A Prelimi/Jaf}' Examinali
on
oj/
he
Pal
iem
Supernumerary
Teeth
Supernumerary (extra teeth) or co
ng
enitally mi
ss
ing teeth occur Quite frequently
among patient
s.
u
The most
common
situation
of
a supernumerary tooth
is
a meso-

dens between the central incisors, which may prevent their nonnal eruption. The
most frequent missing teeth are the upper laterals (see
Fig.
F5.30), followed
by
the
lower second bicuspids, the upper second
bi
cuspids, and
low
er incisors.
Of
course, the
third molars (wisdom teeth) arc missing
in
a lar
ge
percentage
of
the population.
Third
Molars
The role
of
mandibular third molars
in
the relapse
of
lower anterior crowding after
the cessation

of
retention in orthodontica
ll
y treated cases has provoked much specu·
lation
in
the dental literature over many yea
rs
.21
Most practitioners are
of
the opinion
that third molars sometimes produce crowding
of
the mandibular anlerior teeth.
2
•
A
number
of
studies over recent years ha
ve
substantiated very clearly that the presence
of
third molars does not appear to produce a greater degree
of
lower anterior crowd·
ing than that which occurs in patients with no third molars.
21
.

29
Therefore, the
recommendation for mandibular third molar removal with the objective
of
relieving
interdental pressure and thus alleviating
or
preventing mandibular
in
cisor crowding
is
not justified. 28,29
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elan MK, Moss
RB
Jr

Powell
RS,
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BA
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378
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WR
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ig
KW
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Br
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McFadd
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WM
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ON
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Am

J Orthod Dcntofacial Orthop 96:43- 46, 1989.
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SE
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DO.
McNeil
MH
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HW
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Am
J Orthod 69:
37
1- 387,
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76.
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Co
m H: Soft-tissue management
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Onhod

72:5]-64
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1
5.
Bo
yd
Rl
: Clinical assessment
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Am
J
Onhod
82
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78-
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SE
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Am
J
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ci

al
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1
7.
Wisth PJ, Norderal K, and Boe OE: Periodontal status of orthodontically treated impacted
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6.
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18.
Lagerstom
L.
and Kristcrson L: Influence
of
orthodon
ti
c treatment on root development
of
autotrans-
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Am
1 Orthod
89:
[46- 1 50,

1986
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19.
Andreasen JO. Paulsen
HV
, Vu
Z.
Ahlquist R, Bayer T. and Schwartz
0:
A long-t
enn
study
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370
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Onhod
\2
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of
maxillary cuspids. A fo
ll
ow-up study. Br 1
Orthod
12
:
14{I
-
14
7,

1990.
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ral
incisors caused by ectopic eruption
of
the
cuspids. Am J Orthod Dentofacial Orthop 94:503
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13, 1988.
22.
Shapira Y, and
Kun
inek
MM
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Chapler 4 Radiographic El'uillufion •
19
23.
Laptook T. and Silling
G:
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Am
Den
t
Assoc
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46
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8,
[9&3.
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LR
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ater
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m
axi
lla
ry
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io
n. Journal
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nd
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ty
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rt
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ic
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Ka
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ird
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J Orthod 66:4
11
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AG
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Study
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e
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la
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ip
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ird
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e mandibular dental arch.
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ha
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