Standards to judge the outcome
• hard tissue
• Soft tissue
• Andrew’s “Six keys to Normal Occlusion” would be a
good starting point at which to aim in order to get
desired tooth alignment. These are :
Mesio-distal crown angulations (TIP)
Labio-lingual crown inclinations (TORQUE)
Absence of rotations
Occlusal plane (curve of spee)
This key consists of
1] The mesiobuccal cusp of the permanent maxillary first
molar occludes in the groove between the mesial and
middle buccal cusps of the permanent mandibular first
2) The distal marginal ridge of the maxillary first molar
occludes with the mesial ~marginal ridge of the
mandibular second molar
3) The mesiolingal cusp of the maxillary first molar
occludes in the central fossa of the mandibular first
4) The buccal cusps of the maxillary premolars have cuspsembrasure relationship with the mandibular premolars.
5) The lingual cusps of the maxillary premolars have cuspfossa relationship with the mandibular premolars.
6) The maxillary canine has cusp-embrasure relationship
with the mandibular canine and first premolar. The tip
of the cusp is slightly mesial to embrasure.
7) The midlines of the arches match.
• It is the angle formed by the facial axis of
clinical crown [FACC] and as line
perpendicular to the occlusal plane.
• POSITIVE , if occ . of FACC mesial to gin.
• NEGATIVE, if occ. of FACC distal to gin.
Key II. Crown angulation
• It is the angle between as line perpendicular to the occlusal
plane and as line that is parallel and tangent to the FACC
• + OCC. Portion of crown is Facial to gin. portion
• - OCC. Portion of crown is lingual to gin. portion
• Consistent patterns in crown inclination exist. The individual
teeth have the following characteristics.
1) Most maxillary incisors have as positive inclination;
mandibular incisors have a slightly negative inclination. In
most of the optimal sample,
2) The inclinations of the maxillary incisor crown are generally
positive, the central more positive than the laterals. Canine
and premolars are also similar.
The inclination of the maxillary first and second molars are
also similar and negative, but slightly more negative than those
of the canine and premolars.
The molars are more negative because they are measured
from the groove instead of from the prominent facial ridge.
From which the canine and premolar are measured.
3) The inclinations of the mandibular crowns are progressively
more negative from the incisors through the second molars.
NON- ORTHODONTI C NORMS
Absence of rotations
• There should be no undesirable rotations
• Rotated molar or bicuspid occupies more space
• A rotated incisor can occupy less space
• Rotated canines adversely affect esthetics and
may lead to occlusal interferences.
Key VI. Curve of spee
• A flat occlusal plane should be a treatment
• Measured from the most prominent cusp of the
lower second molar to the lower central incisor,
• No Curve of Spee was deeper than 1.5 mm in
the non-orthodontic normals.
• The depth of the curve of spee range from a
flat plane to a slightly concave surface
• An excessive curve of spee restricts the
amount of space available for the upper teeth,
which must then move towards the mesial and
distal, thus preventing correct intercuspation.
• A normal occlusion has a flat occlusal plane.
• The reverse curve of spee creates excessive
space in the upper jaw, which prevents
development of the normal occlusion.
• However, these need to be further
qualified by including functional goals
in our treatment plan.
Optimum Functional Occlusion
• When the mouth closes, the condyles are in
their most superio-anterior (MSSP) position,
resting on the posterior slopes of the
articular eminences with the discs properly
interposed. In this position there is even &
simultaneous contact off all the posterior
teeth . The anterior teeth also contact but
more lightly than the posterior teeth.
• All tooth contact should provide axial
loading of the occlusal forces.
• When a tooth is contacted
on a cusp tip or a relatively
flat surface such as the
crest of a ridge or the
bottom of a fossa, the
resultant forces are
directed vertically through
its long axis.
• When a tooth is contacted
on an incline, however, the
resultant force is not axial
but rather a horizontal
component is incorporated
that tends to cause tipping
with greater likelihood of
• The process of directing occlusal forces through the
long axis of the tooth is known as : Axial Loading
Axial loading can be achieved by
Cusp tip to flat surface contact
that are perpendicular to the
long axis of the tooth.
each cusp tip contacting an opposing
fossa be developed such that it
produces three contacts surrounding
the actual cusp tip.
• Any movement of the mand. From the
intercuspal position that results in tooth
contacts has been described as eccentric.
• Three basic eccentric mandibular
• LATEROTRUSIVE :
• Buccal cusp to buccal cusp
contacts are more desirable
movements than are lingual
cusp to lingual cusp.
• Laterotrusive contacts must
provide adequate guidance
to disocclude the teeth on
the opposite side of the
arch (medio-trusive or the
non working side)
• Medio-trusive contacts can be
destructive to the masticatory
system b’coz of the amount &
direction of the forces that
can be applied to the joint &
the dental structures.
• Some EMG studies suggest
that the presence of mediotrusive contacts on the
posterior teeth increases
• Medio-trusive contacts should,
therefore be avoided in
developing an optimum
• When the mand moves into a latero-trusive
position, there should be adequate toothguided contacts on the latero-trusive
(working) side to disocclude the mediotrusive (non-working) side immediately.
The most desirable guidance is provided by
the canines (canine guidance).
• When the mand is
moved in a right / left
excursions, the max &
mand canines are the
appropriate teeth to
contact & dissipate the
horizontal forces while
• This condition is called
• Lever system of the mand
• Comparable to a nut cracker
• Greater force can be applied
to an object as its position
nears the fulcrum.
• Hence, the damaging horizontal
forces of eccentric mand movements
must be directed to the anterior
teeth, which are positioned farthest
from the fulcrum & the force
• Thus, the amt of force applied to
the ant. teeth is less than would be
applied to the post. teeth , & the
likelihood of breakdown is minimized.
• Of all the teeth canines are best suited to accept
the horizontal forces of eccentric movements
• They have longest & largest roots & therefore, the
best crown – root ratio.
• They are surrounded by dense compact bone which
tolerates forces better than does medullary bone
found around the posterior teeth.
• Sensory inputs: fewer muscles are active when
canines contact during eccentric movements than
when posterior teeth contact.
• Lower levels of muscular activity would decrease
forces to the dental & joining structures &
When canines are no in proper position to
accept horizontal forces, other teeth must
contact during eccentric movements.
The most favorable alternative to canine
guidance is the Group Function : several
teeth on the working side contact during
The most desirable group function consists
of the canines, premolars & sometimes the
mesio-buccal cusp of the 1st molar.
Contacts post. than the mesial portion of
the 1st molar are not desirable b’coz of the
increased amt of force that can be placed
as they near the fulcrum & force vectots.
• PROTRUSIVE MOVEMENTS
• When the mand moves into a protrusive
position, there are adequate tooth guided
contacts on the anterior teeth to disocclude
all the posterior teeth immediately.
• In the alert feeding position, posterior tooth
contacts are heavier than the anterior tooth
• When the mand moves forward into protrusive
contact, damaging horizontal forces can be applied to
• Therefore, anterior teeth & not the posterior teeth
should contact & the anterior teeth should provide
adequate contact or guidance to disarticulate the
• Thus, anterior & posterior teeth function quite
• Anterior teeth are in proper position to accept the forces
of eccentric mand movements & function most effectively in
guiding the mand during eccentric movements.
• Posterior teeth function effectively in accepting forces
applied during the closure of the mouth.
• This condition is described as
“Mutually Protected Occlusion”
Soft tissue parameters
Upper / lower lips to E – line
Upper / lower lips to s- line
Angle of convexity
Methods of evaluating outcome
• Material used :
• Methods used :
– Palatal rugae
• Indices :
Par (peer assessment rating)
ICON (index of complexity , outcome and need )
ITRI (ideal tooth relationship index )
Littles irregularity index
• Peer assessment rating
• Developed in 1987
• Provides a score for various occlusal
traits which make up a malocclusion
Conventions for the PAR Index
– 1. All scoring is accumulative.
– 2. There is no maximal cut-off level.
– 3. The occlusion should be scored disregarding
– 4. The contact points between first, second,
and third molars are not recorded
• 5. If the contact point displacement is as a
result of poor restorative work (restorations or
crowns), the displacement is not recorded.
• 6. Contact points between deciduous teeth are
• 7. Extraction spaces are not recorded if the
patient is to receive a prosthetic replacement.
However, if space closure is intended, the
distance between adjacent teeth should be noted.
• Canines: .~
• 1. Where there are missing canines, displacements
resulting from discrepancies between the mesial
contact point to the first premolar and the distal
of the lateral incisor should be recorded in the
• 2. Canine cross-bites should be recorded in the
• 3. Contact points between the canines and premolars are
scored as follows' the distal contact point of the canine to
the midpoint on the mesial surface of the adjacent
• If a tooth is unerupted and displaced from the line of the
arch either buccally or palatally due to insufficient space,
this is regarded as an impaction. However, if the tooth is
erupted and displaced, the displacement score is recorded.
• 1.) If there is agenesis of the upper incisor or
the tooth has been lost due to trauma or caries
the procedure is as follows:
– a. If the space is maintained (for a prosthesis), the
distance between adjacent teeth is not recorded;
– b. If the space is to be closed, the distance between
adjacent teeth is recorded.
• 2. When recording an overjet, if the tooth falls on the line
the lower grade is recorded.
• 3. If a lower incisor has been extracted or is missing, the
centerline is not recorded.
– 1. Contact points between first and second molars are
– 2. If the first molars have been extracted, the contact
point of the second molar is recorded.
• 30 % reduction was needed for a
case to be judged improved
• Change in score of 22 – considered
Index of Complexity,
outcome and Need (ICON)
• General Assumptions of the Index
• 1. When the index is used to assess treatment outcomes, it is
assumed that an appropriate level of co-operation was obtained
from the patient.
• 2. The index may require confirmation of the presence of teeth
• 3. Except for the aesthetic assessment, occlusal traits are not
scored to deciduous teeth unless they are to be retained in the
permanent dentition to obviate the need for a prosthetic
replacement, for example, when the permanent tooth is absent.
• A sample which looses less than 20
• A sample which looses more than 30
•Occlusal analysis was developed that looked at :
• interproximal contacts
•anterior occlusal contact
• specific cusp and marginal ridge relationships.
-------------------------------•The use of an ideal tooth relationship index (ITRI) :
•evaluating the results of rthodontic treatment
• posttreatment stability
•different orthodontic treatment modalities.
Assuming that all teeth are present, there are 62 potential ideal
tooth relationships that make up ITRI
•BASIS :: The index was based on the percentage of actual to
potential ideal relationships present on the dental casts and was
calculated as the sum of maxillary buccal cusps, mandibular
lingual relationships, and anterior and interproximal contacts
divided by the number of potential relationships.
•The ITRI scores were computed for the
• total index score for the entire dentition;
•anterior segment score, which is the
summation of intraarch and interarch scores;
• posterior segment score, which is the
summation of intraarch and interarch scores,
including buccal and lingual scores.
•"The number of potential ideal relationships varied depending on the number
of teeth included, i.e., extraction cases and inclusion of second molars. The
relationships were scored only when they were correct, and no range of normal"
was incorporated. However, if a buccal segment interdigitated mesially or
distally to the Class I position, contacts were still counted as being present since
functional inclined plane relationships were of primary interest.
•Models with congenitally missing teeth, questionable articulation, malformed
teeth, or broken or chipped teeth were not included in this study.
• Third molars were not included because of variability in
form and occurrence.
• Second molars were included initially but subsequently
eliminated on the basis of a pilot study that revealed no
difference in scores if only first molars were included.
Deciduous teeth were excluded.
• In some cases, band spaces were present resulting in a lack
of interproximal contact; these were not recorded as
Shortcomings of ITRI :
•No range was incorporated into the presence or the absence
of ideal relationships. Thus a correction of 95% would still be
counted as a missed relationship. This stringency tends to
mask much of the improvement that may be very acceptable
clinically and may help to explain why treatment scores
appear to be low.
• In interpreting changes that occurred, one must be aware of
what level or component of the index is being discussed.
LITTLES IRREGULARITY INDEX
• SCORING CRITERIA
0 - PERFECT ALLIGNMENT
1-3 - MINIMAL IRREGULARITY
4-6 - MODERATE
7-9 - SEVERE
10 - VERY SEVERE
• Photographs of boys and girls
between 11-13 and 14- 16 yrs were
collected in 4 albums
• Spatial change of craniofacial structures
is evaluated by superimposition of
cephalometric tracing taken at different
• Methods of superimposition differ acc. To
reference structures used within the skull
Superimposition can be
• 1 ) cranial base
• 2) maxilla
• 3) mandible
The average of side effects on mandibular rotation is as follows;
1) Convexity reduction:
Facial a.xis opens 1 degree/ 5mm
2) Molar correction:
Facial a.xis opens 1 degree / 3mm
3) Overbite correction:
Facial axis opens 1 degree /4mm
4) Cross bite correction.: Facial axis opens 1-1 1/2 degree
5) Dolico facial pattern :Tendency for facial a.xis to open 1 degree per 1 S.D.
6) Brachy facial pattern: , Tendency for facial axis to close 1 degree
Facial a.xis may close with extraction.
• The point A changes with various mechanics is as
• MECHANI CS
b) Class II Elastics
d) Torque 2mm
e) Class 111Elastics 3mm
f) Face Mask 4mm.
• Present approach views the correction of
malocclusion molar relationship and overjet-as the
end result of a series of physical displacements
• growth and tooth movement
• displacement of maxilla relative to cranial base,
• movement of maxillary dentition relative to
maxillary basal bone,
• translation of mandible relative to cranial base,
• movement of mandibular dentition relative to
mandibular basal bone.
• Component displacements are measured in a comparable
manner and each is given a sign appropriate to its impact:
• positive if it would tend to correct a Class II molar relationship or
reduce overjet (as would be the case, say, with forward growth of
the mandible or mesial movement of the lower molars and incisors);
negative, if it increases the overjet or moves the molar
relationship toward Class II (e.g. as with forward growth of the
maxilla or mesial, movement of the upper dentition).
• Given this sign convention, the algebraic sum of the various
antero-posterior skeletal and dental effects would equal
the change in molar relationship and overjet.
The use of palatal rugae for the assessment
anteroposterior tooth movements
• The purpose of this study was to assess the relationship
between posterior occlusion and posttreatment changes in
other occlusal variables.
• 1. Anteroposterior molar and incisor movement maybe
assessed as accurately with dental casts as with maxillary
• 2. The medial end of the third palatal ruga is a suitable
landmark for serial model analysis of molars and incisors.
• 3. The use of study models to evaluate anteroposterior
anchorage, particularly during treatment, presents the
clinician and the researcher with an alternative to taking a
cephalometric radiograph, given the limitations of not being
able to evaluate incisor tipping or vertical movements.
Orthodontic treatment outcome of
Assessing treatment effectiveness of removable and fixed
orthodontic appliances with the occlusal index
Orthodontists from different backgrounds may have different
opinions about removable and fixed orthodontic appliances, but
there have been few objective comparisons of their relative
In this study – 80 cases removable
- 67 fixed
The Occlusal Index was proposed by Summers in 1966.1
Nine weighted and defined measurements were included in
the Occlusal Index:
posterior open bite
maxillary median diastema
congenitally missing maxillary incisors.
•The average reduction in Occlusal Index scores after therapy with removable
orthodontic appliances was found to be less than that obtained with fixed
appliances,the improvement in occlusion produced by fixed appliances was
much greater than that produced by removable appliances.
• Most of the patients treated with fixed appliances had major reductions in OI
scores, especially those with the most severe pretreatment malocclusions compared
to patients who had been treated with removable appliances showed major reductions
in OI scores, many had only minor reductions. This inconsistency indicated that
treatment effects and treatment results produced with removable appliances were
much more variable and less predictable than those obtained with fixed appliances.
•The removable appliances tend to correct symptoms of malocclusion rather
than the basic orthodontic defect
•Begg and Edgewise appliances were compared, the present study found no
statistically significant difference between their treatment effectiveness or
their treatment results
•REMOVABLE APPLIANCES not effective in moving the tooth bodily ,
close extraction spaces, mesiodistal , buccolingual inclinations. They can
•Kerr (bjo 1993 ) :removable appliances only effective in treating crossbite ,
ectopic tooth position , ant. Spscing, overjet and less in rotation , crowding ,
Comparison of the Outcome of
treatment Using Two Fixed Appliance
Comparison of the two different appliiance types found that the
pre-adjusted Edgewise group achieved a significantly greater
reduction in PAR score (81 per than the Begg group (65 per cent).
Cases with a low PAR score prior to treatment tended to fare
more poorly in terms of percentage reduction and this was more
marked for those cases treated with the Begg appliance
. Although the index has a high degree of reproducibility, it was
found that even the small error present can lead to problems of
“interpretation if the nomogram categories are used as a method
• Hypothesis : functional appliances enhance
mandibular growth in the treatment of skeletal
Class II malocclusions.
Previous studies have shown varying degrees of
success in the treatment outcomes, functional
appliance use remains controversial.
A treatment outcome that has been particularly
questioned is the enhancement of mandibular
• It was not until the 1970s that the use of functional
appliances became widespread in the United States.
This was, in part, the result of landmark studies in animals
that demonstrated that skeletal changes could be produced
by posturing the mandible forward.
• The initial studies seemed to validate the concept that soft
tissue stretching can promote bone growth.
• Many studies followed, but later studies performed on
humans were more equivocal and showed less impressive
Therefore, the controversy remains regarding the efficacy
of functional appliances to correct Class II malocclusions.
• It is currently difficult to obtain definitive answers about
appliance efficacy from the literature because of many
inconsistencies in measuring treatment outcome variables
Some investigators use condylion (Co) as the posterior end
point in measuring the overall mandibular length, whereas
others use articulare (Ar).
In addition, durations of treatment vary, as do the lengths
of follow-up; and treatment groups are sometimes compared
with untreated control groups or with groups undergoing
other forms of treatment, such as headgear.
• Illing et al, 1998 Bass, Bionator, Twin-block
Ghafari et al, 1998 Fra¨nkel Headgear
• Cura et al, 1997 Bass
• Tulloch et al, 1997 Bionator
• Webster et al, 1996 Fra¨nkel & Harvold
• Nelson et al, 1993 Fra¨nkel & Harvold
• Linear measures were assessed:
• condylion-pogonion (Co-Pg)
• articulare-pogonion (Ar-Pg),
• Condylion-gnathion (Co-Gn)
• articulare-gnathion (Ar-Gn)
• sella-gonion (S-Go)
• articulare-gonion (Ar-Go)
• condylion-gonion (Co-Go).
• Two angular parameters:
sella-nasion-B point (SNB)
lower incisal angle (LIA),
• Three horizontal measurements :
• gonion-menton Go-Me)
• pogonion to N (Pg to N),
• gonion-pogonion (Go-Pg).
For Co-Pg, Co-Gn, SNB, LIA, and other horizontal measurements, there is
no significant difference between the untreated control group and the
group treated with functional appliances.
However, for Ar-Pg and Ar-Gn, there was a significant difference between
the control and the treated groups.
Although these appliances can be used for other purposes, these results
suggest the need to reevaluate functional appliance use for mandibular
These results complement those of quasi-experimental studies with
discriminant analysis but differ from nonsystematic reviews that provide
qualitative summaries. (Am J Orthod Dentofacial Orthop 2002;122:
Occlusal outcome of ortho
• Ajo 1992
• 92 treated malocclusions consisting of 36 Class I, 25 Class
II, Division 1, 17 Class II, Division 2, and 14 Class III
malocclusions were obtained.
• The dental casts were analyzed
• before treatment (A)
• at the time the appliance was removed (B)
• approximately 4 years later (C).
Total index scores improved from 26.8% to 52.1% as a result of orthodontic
treatment and increased to 58.7% during the posttreatment period,
• Orthodontic treatment improved ideal tooth relationships, which generally
continued to improve during retention thus reflecting a settling effect.
• Analysis of treatment results showed that anterior segments improved more
than posterior segments, and buccal relations are handled better than lingual
relations. It appears orthodontists do a better job correcting discrepancies
that are more highly visible.
•. Occlusal relationships after orthodontic treatment were improved to
approximately the same degree regardless of the type of malocclusion and,
thereafter, showed similar settling and relapse.
• Before treatment
• Class I : higher total ITRI
• Class II : higher posterior ITRI
• After treatment
• No difference
• Post retention
• Class II div I : 15% higher in posterior
Does growth affect occlusal
Assessment of biological changes in a non orthodontic sample using
the PAR index(Am J Orthod Dentofacial Orthop1998;)
The results indicate that there were no significant differences between the mean
Peer Assessment Rating score at 12 years of age and at 22 years of age
The changes were irrespective of the Angle classification or the treatment need.
Changes over time in the weighted Peer Assessment Rating score were mainly
correlated to changes in the anterior crossbite and the overjet.
This correlation may be influenced, however, by the applied weighting factor for
those occlusal traits.
Stability of orthodontic
Orthodontic treatment need prior to tretment
and 5 years postretention
• (community dent oral epi 1998)
Dental casts evaluated using IOTN
– on the basis of combined dhc and ac scores 83 % of pt. who
started ortho treatment had an objective need for ortho
– 10 % still showed a definite need
• in another study by burger (1995) showed 44 % of
patients who showed a definite need
• The remaining treatment need showed a correlation with
the year of ortho treatment was started
• But treatment duration did not diminish although treatment
tech. has evolved
• There seems to be a secular trend in ortho outcome but
effectiveness in terms of treatment duration did not
• .(i) Personal factors
• Age at start of treatment
• (ii) Occlusal factors
• Incisor classification (Class I, III I , III2 or III, according to
• Standards Institute definition)
• Developmental stage (mixed dentition, permanent dentition)
• Pretreatment PAR score
• Size of overjet (mm)
• Presence/absence of anterior crossbite
• Presence/absence of ectopic teeth
• (iii) Co-operation factors
• Pretreatment oral hygiene (good. fair, poor. no
• Number of broken appointments
• Number of removable appliances broken or lost
• Number of bands/bonds dislodged or archwires
• Whether or not the original treatment plan was
• treatment factors
• Appliance type (two-arch fixed, removable/mini-fixed)
• grade (consultant, senior registrar, postgraduate
• Extrction pattern (non-extraction, four premolars, first
• No. of removable appliances used
• Whether or not headgear was worn
• Outcome variables
Post-treatment PAR score
Change in ,PAR score
Duration of active treatment
No. of appointments during active treatment
Timing of ortho
• a recent workshop on early treatment, the majority of the
participants estimated that the 30% to 50% of their
practices involves patients who, in their opinion “NEED an
early phase of treatment.”
a 2-stage approach, particularly applied to the most common
problems encountered in clinical practice —the resolution of
crowding and Class II malocclusions.
• Crowding can be resolved in most instances by
simple arch length preservation
There is no clinically important difference in the
outcomes of 2-stage and 1-stage Class II
treatment except for a longer treatment time in
the 2-stage samples.
• An evidence-based approach has at least 2 components.
• One is composed of individuals who pursue information by
means of rigorous hypothesis testing involving formulating
an appropriate question, reducing variability, collecting
data with a defined protocol, and analyzing the data by
means of an accepted method.
• The second component comprises practitioners whose duty
is to evaluate the merits of new data before adopting a
practice strategy based on the findings.
• This scenario raises an important issue on the eve of the
• Will orthodontics accept an “evidence-based” approach to
Is orthodontics ready to alter treatment strategies if the
purported claims are not supported by fact?
An evidence-based approach is attractive for a number of
One is that it will serve our patients better because only tested
strategies will be endorsed.
• A second is that it will elevate orthodontics to a higher level
because it will ensure that we are offering proven treatments.
• In the final analysis, the practitioners will control
the destiny of evidence-based treatment
strategies in orthodontics because they are
responsible for transferring information to their
• This is one of the many reasons that the future
of the specialty is in their hands.
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