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An Index is an objective mathematical
description of a disease or condition based on
carefully determined criteria under specified
•indices have been developed to
–identify patients with treatment need
–prioritize their treatment needs
–be useful tools in epidemiological studies.
• Early methods of recording malocclusions were
qualitative &used for epidemiological studies.
• The more recognized qualitative methods were developed
by angle, stallard, mccall &many others.these methods
identified only the presence or absence of a malocclusion
• In early 1960's attempts were made to develop
quantitative methods to measure the severity of
malocclusion to rank the need for orthodontic treatment.
• These included the mal-alignment index by vankirk
&pennel,drakers handicapping labio-lingual deviation
index,graingers malocclusion severity estimate,summers
occlusal index&many more.
• Indices measuring the aesthetic factor as representative
of social sufficiency have emerged as important
instruments for determining ttt priorities.
Indices measuring occlusal variation were divided into
five types by grainger in 1961.these were further divided
into three categories by moyers &summers.
• a)Syndromic type indices of incidence & prevalence of
specific symptoms or groups of symptoms for use in
• b)Indices of incipient or potential malocclusion are necessary
for the conduct of preventive dental health programs.
• a)indices used as an aid to clinical diagnosis
– a)indices of confirmed dental anomalies used to
select the cases with the highest ttt priority from a
population purely on the basis of the severity of the
deformity or handicap.
– b)indices pointing out the degree to which ttt
requirements are being met in population.
Two more types under the last category are:
– c)indices which assess the relationship between
occlusal morphology & the need for ttt based on the
– d)indices which assess the relationship between
morphology & the need for ttt based on psychological
Malocclusion is ‘any deviation from normal occlusion
of teeth.the teeth are in abnormal position in relationship to
the basal bone of the alveolar process,to the adjacent
teeth&/or to the opposing teeth.according to angle occlusion
is`the normal relation of the occlusal inclined planes of the
teeth when the jaws are closed’.
We need an index to:
• Document the prevalence & severity of
• For provision of orthodontic treatment in a
• For training of orthodontic specialists.
Requirements of an index:
• Status of the group is expressed by a single number
which corresponds to a relative position on a finite scale
with definite upper &lower limits; running by progressive
gradation from zero, i.e., Absence of disease to the
ultimate point ,i.e.,disease in its terminal stage.
• Should be equally sensitive throughout the scale.
• Should correspond closely with the clinical importance of
the disease stage it represents.
• Should be amendable to statistical analysis.
- Requisite equipment &instruments should be
practicable in actual field situation.
- Examination procedure should require a minimum
- Should be facile enough to permit the study of a
large population without undue cost in time or
- Permit the prompt detection of a shift in group
conditions,for better or for worst.
- Should be valid during time.
METHODS OF RECORDING MALOCCLUSION
The methods of recording &measuring
malocclusion can be classified into two types:
Qualitative methods were devised mainly for
epidemiological studies. A summary of some
important qualitative methods is presented in the
Summary of the qualitative methods of recording
Classification of molar relationship devised as a
prescription for ttt.
The general dental status,including some
malocclusion symptoms,was recorded.
No definition of various symptoms was described.www.indiandentalacademy.com
Malocclusion symptoms recorded include:molar
relationship, posterior crossbite , anterior
crowding,rotated incisors,excessive overbite, openbite,
labial or lingual version,tooth displacement,constriction
No definition of these symptoms were specified.
Symptoms were recorded in all or none manner.
Specific malocclusion symptoms were
-Angle's classification of molar relation,
-Arch constriction with/without incisor crowding,
-Superior protrusion with incisor crowding,
-Superior constriction without incisor crowding,etc.
•Objective registration of malocclusion symptoms
based on detailed descriptions.
1-Anomalies in Dentition : Tooth anomalies,
3- Occlusal anomalies.
Five major groups of items were recorded:
1 - Gross anomalies
2 - Dentition
3 - Space dentitions
4 - Occlusion
5 - Orthodontic ttt need
KINAAN & BRUKE(1981):
FIVE FEATURES OF OCCLUSION MEASURED:
1 – Overjet(mm)
2 - Overbite(mm)
3 - Posterior crossbite(no of teeth in
crossbite, unilateral or bilateral)
4 - Buccal segment crowding or
5 - Incisal segment alignment(classified as
rotated,following defined criteria).
Some methods are described below:
1)ANGLE'S METHOD OF CLASSIFYING
MALOCCLUSION(1899) has been widely accepted
and used since it was first published in 1899.
According to him, the malocclusion is based
on antero-posterior relationship of the teeth. He
employed numerals I, II & III to designate the
three main classes.
He employed arabic numerals1,2 to denote
the division of classification. Unilateral
deviations were termed as sub-division.
He considered maxillary first molar to be the
key to occlusion
Mesio-buccal cusp of the
upper first permanent molar
occludes with mesio-buccal
groove of the lower first
permanent molar.this class
also includes cases of
irregularity of individual
teeth & does not include
malrelation of the dental
The disto-buccal cusp of the upper first
permanent molar occludes with the mesio-buccal
groove of the lower first permanent molar.
– DIVISION-1- All the upper incisors are proclined.
– DIVISION-2- All upper central incisors show
retroclination &the lateral incisors overlap the central
– CLASS-II SUBDIVISION
Class II molar relation on one side only &class I on
Class II Division 1 Class II Division 2
• CLASS III
Lower first permanent molar
lies mesial to upper first
permanent molar by a
premolar width or a cuspal
• CLASS III SUBDIVISION
Unilateral class III molar
relationship &class I on
– It is based on venn diagrams.
– It has 9 groups.
– 5 step procedure to access malocclusion.(no definite
criteria for assessment was given)
i) Alignment- ideal,crowding,spacing,mutilated.
ii) Profile - mandibular prominence,mandibular
recession,lip profile relative to nose
iii) Cross bite-relationship of the dental arches in the
transverse plane as indicated by buccolingual
relationship of posterior teeth.
iv)Angle's classification - relationship of the dental
arches in sagittal plane.
v)Bite depth -relationship of the dental arches in
the vertical plane,as indicated by the presence or
absence of anterior open bite,anterior deep
bite,posterior deep bite&posterior collapse bite.
On the basis of the principles developed for
defining &recording individual traits of
malocclusion by bjork et al a simplified method
was developed during the years 1969-72 working
group 2 (wg2)of fdi commission on classification
& statistics for oral conditions.
During 1973-76, the method was field tested
& modified & published in 1979.The primary
objective of the assessment method was to
determine the prevalence of malocclusion &
dental irregularities & to estimate the treatment
needs of the population as a basis for the
planning of orthodontic services.
Summary Of Quantitative Methods Of
MASSLER & FRANKEL(1951):
Count the no of teeth displaced or rotated.
(all or none assessment)
MALALIGNMENT INDEX (VANKIRK &
Tooth displacement & rotation were
measured (defined quantitatively)
HANDICAPPING LABIO-LINGUAL DEVIATION
Measurements include cleft palate,traumatic deviations,
overjet, overbite, mandibular protusion, anterior
openbite, labio-lingual spread.
OCCLUSAL FEATURE INDEX (POULTON &
-Measurements include lower anterior crowding, cuspal
interdigitation, overbite & overjet.
-Occlusion features were measured & scored according
to defined criteria. www.indiandentalacademy.com
Handicapping Malocclusion Assessment Record
Weighted measurements consist of two parts:
- Intra-arch deviation-missing teeth, crowding,
- Inter-arch deviation-overjet, overbite,
crossbite, openbite, mesio-distal deviation.
Six handicapping dento-facial deformities:
- facial & oral clefts
- lower lip palatal to maxillary
- occlusal interference
- functional jaw limitation
- facial assymetry
- speech impairment
this part can only be assessed on life
Some indices are described below:
1)Malocclusion Severity Estimate (mse-1960-61):
Grainger developed the mse in
the burlington research center. It can be used
either on the models or on the patients. It was
found to be highly reproducible. It was later revised
& was called as treatment priority index.
2)OCCLUSAL INDEX (SUMMERS-1966)
• Based on malocclusion severity estimate with
attempts to remedy its shortcomings.
• The first shortcoming was remedied in part by
defining normality over time, in particular
equating the mixed dentition analysis with actual
tooth displacement & in part by giving different
weights to certain items in different dental age
groups. If these items would have their norms
changing as dental development proceeded.
• A scoring scheme for each stage of dental
development i.e; deciduous, mixed & permanent)
was therefore developed & different scoring
forms were used for subjects in each stage.
- The second shortcoming was remedied by
considering the scores of all syndromes in arriving
at the final score.
- The third shortcoming was remedied by adjusting
for normality,so that the absence of any occlusal
disorder would be scored as zero.
3)TREATMENT PRIORITY INDEX(TPI-1967)
Grainger modified the mse to develop the tpi.
He described the index as a method of assessing
the severity of the most common types of
malocclusion & hence provided a means of
ranking patients according to the severity of the
malocclusion, degrees of handicap or their
priority of treatment.
The pre requisites for determining the
handicap was defined by grainger as:
• unacceptable aesthetics
• significant reduction in masticatory function
• traumatic condition predisposing to tissue
• speech impairment
• unstable occlusion
• gross or traumatic defects
• a few manifestations of malocclusion, such as
midline diastema & slight asymmetry were
rejected & also the mixed dentition analysis
4)HANDICAPPING MALOCCLUSION ASSESSMENT
Handicapping malocclusion & handicapping
dento-facial deformity were defined as conditions
that constitute the hazard to maintenance of oral
health and interfere with the well-being of the
patient by adversely affecting dento-facial
aesthetics, mandibular function,or speech. a cut
off point was set at a score so that those patients
whose scores were above the cut off point would
be treated by professional personnel.
2 - Post-normal occlusion with lip trapping (e.g;overjet
greater than 10mm)
-Prenormal occlusion with mandibular displacement.
-Increased overbite with gingival trauma/irritation.
-Severe anterior openbite involving premolar units.
-Severe posterior crossbite with mandibular
-Severe anterior crowding or spacing.
-Impacted maxillary canines.
-Aesthetically or functionally disturbing rotations.
3)Deviations in space condition.
-Infra-occlusion of permanent posterior teeth.
-Anterior openbite involving the canine region.
-Severe crowding of posterior teeth.
-Spacing of posterior teeth including posterior tooth aplasia.
-Aesthetic or functionally disturbing rotations.
4 ) Mild deviations from normal occlusion.
-Prenormal occlusion with little negative overjet or
-Post-normal occlusion without other anomalies.
-Increased overbite,i.e;the upper incisors extend no
further gingivally than the third middle third of the lower
-Minimal anterior openbite affecting the incisors only.
-Minimal transverse crossbite with minimal or no
-Mild crowding or spacing.
-Mild rotations of little aesthetic or functional
5) No ttt required.
VARIOUS OTHER INDICES ARE DESCRIBED
1)THE MALALIGNMENT INDEX: (MASSLER &
FRANKEL - 1951)
This index is based on the individual
tooth as the unit of occlusion.each tooth is
examined by turn to determine whether it is in
correct occlusion or malocclusion.the total no of
maloccluded teeth in an individual is the index
score for the individual.
A maloccluded tooth is the one which falls in
one of the categories:
a)buccal or lingual displacement.
b)mesial or distal displacement.
d)infraoccluded or supraoccluded.
The position of each tooth is assessed by
judging it in relation to the adjacent teeth &
Though a tooth may be maloccluded in more
than one plane it is always assigned a value of one
i.e;a tooth is either maloccluded or not.
The total index score per person may range
from zero for a dentition with no maloccluded teeth
to 28 if all the teeth are maloccluded (third molars
were not included in the original study).
Missing teeth,extracted teeth &
devolopmental anomalies of teeth are recorded
2)THE MALALIGNMENT INDEX (VAN KIRK &
• The index was to serve as an Epidemiological tool &
provide data useful for group & comparative studies.
• The index scores were meant not only to indicate severity
of malocclusion but also to rank the build of problems in
• Measurements are taken with the help of a specially
designed plastic instrument.
• The arches are divided into three segments:anterior &
right & left posterior segments.
• Each tooth is examined & given a score of 0,1 or 2. The
individual tooth scores in each segment are summated to
get the segment score & the final index score is the total
sum of the six segment scores.
The method of scoring is as follows:
• 0 - ideal alignment-
the tooth does not show any apparent
deviation or displacement from the ideal
arch line as projected through the contact
•1 - minor malalignment - which may be of two
i)rotation the angle formed between the line
projected through the contact areas of the observed
tooth & the ideal arch line is less than 45degrees.
ii)displacement i.e;both the contact areas are
removed in the same direction from their position
in ideal alignment but the displacement is less than
• 2 - major malalignment which may again
be again be of two types:
i)rotation equal to or greater than
ii)displacement equal to or greater than
3)THE OCCLUSAL FEATURE INDEX
(POULTON & AARONSON -1961):
This index is meant for epidemiological
surveys & is based on four characteristics of
a)lower anterior arch crowding in the canine to
– 0 - no crowding
– 1 - crowding of lower anterior teeth equivalent to one
half the width of the lower right central incisor
– 2 - crowding the width of one central incisor
– 3 - crowding exceeding the width of one central
b)cuspal interdigitation, observed in
occlusion looking at the right premolar-to
molar area from the buccal aspect.
– 0 - cusp to groove relationship
– 1 - between cusp & groove
– 2 - cusp to cusp
c)vertical overbite,measured by that portion
of the lower incisors covered by the upper
central incisors in occlusion.
• 0 - incisal third of lower incisors
• 1 - middle third of lower incisors
• 2 - gingival third of lower incisors
d)horizontal overjet, measured in occlusion with a
small ruler from the labial surface of the upper
incisors to the labial surface of lower incisors.
– 0 - 0-1.5mm
– 1 - 1.5-3.0mm
– 2 - 3.0mm & over
The values assigned to an individual
correspond to the number of the grade & the
total sum of the four categories gives the
o.f.i.score for that individual.
This index was meant for use in public
health programs.draker defined handicap
as "an extreme deviation from an accepted
norm which may or may not actually
exist.the index incorporates seven features
1 - cleft palate
2 - traumatic deviations
3 - overjet
4 - overbite
5 - mandibular protusion
6 - open bite
7 - labio lingual spread
The sum total of all the traits gives the
h.l.d.score. A score of 13 & over will constitute a
More recently many indices have been
developed. Of these new indices, a few are
1)Dental aesthetic index (cons et al-1986)
2)The IOTN index(brook&shaw-1989)
4)Index of complexity, outcome& need(icon)
1)DENTAL AESTHETIC INDEX (1986 - JENNY &
It has a clinical component & an esthetic
component. The DAI links the components
mathematically to produce a single score that combines
the physical & esthetic aspects of occlusion.
Though it was developed for use in the permanent
dentition,it can easily be adapted for use in the mixed
Instead of counting the number of missing
incisors,canines &premolars,as required in the DAI
regression equation, the following modification is used.
When scoring a case in the mixed dentition,the space
from the recently exfoliated deciduous tooth should not
be scored as missing, if it appears that the permanent
replacement would soon erupt.
The DAI has decision points along the DAI scale
defining case severity levels that approximate the
judgment of the orthodontists.
The DAI scores of 25 & below represent normal or
minor malocclusions with no or slight treatment need.
The DAI scores of 26 through 30 represent definite
malocclusions with treatment elective.
The DAI scores 30 through 35 represent severe
malocclusions with treatment highly desirable.
The DAI scores 36 & higher represent very severe or
handicapping malocclusion with treatment considered
The hypothetical case with a score of 39 would be
considered handicapping & would be found eligible for
receipt of orthodontic care in publicly funded programs
in the United states.
2)INDEX OF ORTHODONTIC TREATMENT
First described in 1989 by brook & shaw as
index of orthodontic treatment priority &later
The IOTN has two components,a clinical
component called the dental health component&
a separate esthetic component.
The clinical component of IOTN is a
modification of the index used by the Swedish
It has five grades.(table shows them). a grade
is allocated according to the severity of the worst
single trait.the grade of this trait describes the
priority of treatment.www.indiandentalacademy.com
• The esthetic component of the IOTN
consists of a visual 10-point scale, which
represents a wide range of dental
attractiveness, illustrated by a series of 10
front view photographs arranged from no-
1(most attractive)to no-10(least
attractive)as shown in the figure.
3)PEER ASSESSMENT RATING (PAR)INDEX(RICHMOND-1990)
Developed at the Manchester university. It was developed to
quantify how much orthodontic treatment reduces the severity of
Scores are assigned to various occlusal traits that make up a
malocclusion. The individual scores are summed & the total
represents the degree to which a case deviates from normal
Improvement in the PAR index can be assessed with either the
point reduction in the weighted PAR score or percentage reduction.
The PAR index includes the scores of 5 individual traits:
upper& lower segments,right& left buccal segments, overjet &
overbite & centerline.
The scoring of each component is shown in the table The raw
PAR score is calculated by adding the individual components of the
PAR score. Weighting is attained to various components to get the
weighted PARscore. www.indiandentalacademy.com
4)Index of Complexity, Outcome and Need (ICON):
This index was created so that a single index
for assessing treatment inputs & outcomes is
obtained. A panel of 97 orthodontists gave
subjective judgments on the treatment need, ttt
The occlusal traits were scored according to a
defined numerical protocol. Five highly predictive
occlusal traits were identified (IOTN-esthetic
component,cross bite,upper arch crowding /
spacing, buccal segment antero-posterior
relationships,& anterior vertical relationship).
This new index is comprised of an assessment
of dental esthetics &other relationships as
The scoring protocols are described in the
table(used in study models). All the treatment score
values greater than 43, would be considered in
need of ttt.
Post ttt scores of less than 31 signify acceptable
end occlusion. These cut-off values were chosen to
optimize the specificity&sensitivity of the index.
5)HLD(CALMOD) & HLD(MD):
Maryland & California are among the states
that have adopted the handicapping labio-lingual
deviation (HLD) index to determine eligibility for
public funding of orthodontic ttt. as a result of
several lawsuits against the state,California has
developed & employed.
A modification of that index,used by several
states rely on morphological deviations from an
idealised norm to determine ttt need.
Maryland uses HLD index to evaluate
orthodontic need of patients who would
require state funding. It has raised the cut-off
from 13 to15 points & modified drakers
original scoring by subtracting 2mm from
overjet &3mm from overbite measurements.
HLD index was modified in California to identify the
most severe malocclusions. These were declared
handicapping & their ttt medically necessary.
Two qualifying exceptions that cause tissue damage
were added - deep impinging bites&cross bites of
individual anterior teeth with tissue destruction.
Later overjets greater than 9mm & reverse overjets of
3.5mm were added as additional qualifying exceptions &
unilateral posterior crossbite was added as a weighted
The HLD(CalMod)index uses a cutoff score of 26
SHORTCOMINGS OF VARIOUS INDICES:
There have been many critiques of angles
classification of malocclusion. His method disregarded the
relationship of the teeth to the face & although
malocclusion was a three dimensional problem,angles
system had only taken into account antero-posterior
deviations in the sagittal plane.
When reliability was tested,between examiner errors as
well as within examiner errors in categorizing angle class
II,div2 malocclusion were relatively high.also there was
difficulty associated with asymmetry between left&right
sides,or those where tooth movements had occurred
because of factors such as crowding&premature loss of
• did not define the malocclusion symptoms to be
recorded,thus malocclusion symptoms were recorded in all
or none manner.
• only a few malocclusion symptoms were selected
arbitrarily as the items to be recorded.
• it was derived from data of 12 year old patients &
therefore might not be valid for earlier stages of dental
development in the deciduous or permanent dentitions.
• it didn't reflect all measurements that were accumulated&
• the absence of any occlusal disorder was not scored as
- very close & careful examination is needed as
subjective decisions were required in deciding
whether the molar relationship is distal or mesial
by half a cusp or more than half a cusp on each
- certain degree of subjective judgment was also
involved in determining displacement by 1.5 to
2mm or more than 2mm.
- requires more calculations & clerical time & a
• a few manifestations were rejected such as midline
diastemas & slight asymmetry.
• mixed dentition analysis was deleted which measures the
potential tooth displacement.
• inadequate for assessing the occlusion of the deciduous or
• inspection of TPI form reveals that distal & mesial molar
relations are considered equal.
• TPI values recorded in the transitional dentition do not
predict the future severity of the malocclusion in the
- the dento-facial deformities can only be
assessed on life patients & not on any study
• poor reproducibility in school settings of dental
• self evaluation of dental esthetics by children
found only slight agreement with examiners
• tendency for children to overrate their level of
attractiveness compared with professional
• poor agreement for esthetic component scored by
calibrated examiners from photographs when
compared with scores recorded clinically or from
• it has been developed & validated to assess ttt
entry & exits as separate phenomenon,when they
are clearly part of the same clinical process.
• this index have been validated against UK dental
opinion & thus may not be representative in
• this index has been criticized for undue leniency
of residual extraction spacing,unfavorable
incisor inclinations & rotations.others have
found it unduly harsh on ttt with limited aims.
• it does not take into account the periodontal
dynamic occlusion & facial esthetics.www.indiandentalacademy.com
RELIABILITY & VALIDITY OF INDICES:
• The precision of an index is an ability to produce the same
score or measurement when one or more examiners
measure the same case at the same or different time.
• The validity of an index can be defined as its ability to
accurately measure what it purports to measure.
• Bias,or systemic error,of an index or measurement is the
magnitude & direction of its tendency to measure
something other than what was intended. The score of an
unbiased index should accurately reflect the intended
characteristics. An index could be precise but biased.in
such a case,the score will be reproducible but not an
accurate potrayal of the occlusion.
EVALUATION OF MALOCCLUSION INDICES:
Of all the indices described so far ,the OI by summers
was evaluated to have the least amount of bias,is best
correlated with clinical standards & has the highest
validity during time.this was evaluated by many authors
thro the years comparing with other indices such as
Newer indices have been evaluated & correlated with
other indices for their precision.
Malocclusion is not just an invariable disease
state,but a continuous spectrum of occlusal
variation,occurring as a myriad of combinations &
permutations of a no of heterogeneous traits or
symptoms,each with its own wide range of severity
& implications in creating a particular
manifestation of occlusion.
A good method of recording or
measuring malocclusion is important for
documentation of the prevalence &
severity of malocclusion in the population
groups.this kind of data is important not
only for the epidemiologist but also for the
training of orthodontic professionals.
There seems to be no universally accepted index for
measuring malocclusion,yet.Although the OI had been
shown to have the least amount of bias,it still has
shortcomings. Further research would therefore be
needed to develop better indices or to refine the present
indices so that they can be more universally
accepted.many of the current indices of ttt standards
show low intra & inter examiner variability when
compared with those used for diagnostic or