WJD
10.5005/jp-journals-10015-1132
An Overview of Orthodontic Indices

REVIEW ARTICLE

An Overview of Orthodontic Indices
Anirudh Agarwal, Rinku Mathur

ABSTRACT
Analysis of prevalence of various types of malocclusion is an
important aspect of today's evidence-based dentistry.
Orthodontic indices are a tool in the hands of an epidemiologist
to analyze the prevalence and severity of various kinds ofmalocclusion. The aim of this article is to look into the various
qualitative and quantitative methods of grading and assessing
malocclusion and their evolution over the years along with theiradvantages and limitations have also been analyzed. The article
also compares the commonly used indices—DAI and IOTN.
Keywords: Malocclusion indices, Dental esthetic index, Indexof orthodontic treatment need.
How to cite this article: Agarwal A, Mathur R. An Overview ofOrthodontic Indices. World J Dent 2012;3(1):77-86.
Source of support: Nil
Conflict of interest: None declared

INTRODUCTION
Over the years, a variety of indices have been developed toassist professionals in categorizing malocclusion according
to the level of treatment need. However, it is the societal
forces that define the norms for an acceptable, normal andattractive physical appearance. Identification by children
and their parents of abnormal, unacceptable and disfiguring
dentofacial characteristics is influenced as much by social
context and cultural milieu as by objective criteria.
A good method of recording or measuring malocclusion
is important for documentation of the prevalence andseverity of malocclusion in population groups. This kind ofdata is not only important for the epidemiologist, but also
for those who plan for the provision of orthodontic treatment
in a community or for the training of orthodontic specialists.
If the method is universally accepted and applied, datacollected from different population groups can be compared.
The methods of recording and measuring malocclusion canbe broadly divided into two types: Qualitative andquantitative. A method that measures malocclusion
quantitatively can also be used to assess treatment effectsof orthodontic appliances.
A review of the literature related to the recording andmeasuring of malocclusion severity found that most of theinvestigations were published between the 1940s and the1970s. In the past decade, there have been relatively few
publications that discussed this topic. In order to fulfill the
research gap, the objective of this article is to review theliterature related to the quantitative and qualitative methodsof recording and measuring malocclusion and to discuss
the two commonly used indices, DAI and IOTN.
World Journal of Dentistry, January-March 2012;3(1):77-86

QUALITATIVE METHODS OFRECORDING MALOCCLUSION
The earliest methods of recording malocclusion werequalitative ones. A summary of the more important methods
is presented in Table 1.
Angle’s method of classifying malocclusion with orwithout modifications has been widely accepted and is stillin use since it was first published in 1899.1 There have been
many critiques of Angle’s classification of malocclusion.
Case2 pointed out that Angle’s method disregarded therelationship of the teeth to the face; and althoughmalocclusion was a three-dimensional problem, Angle’s
system had only taken into account anteroposterior
deviations in the sagittal plane. When reliability was tested
by Gravely and Johnson,3 they found that the betweenexaminer errors, as well as the within-examiner errors in
categorizing Angle class II, division 2 malocclusions, wereboth relatively high. Nonetheless, it must be rememberedthat Angle devised his classification method as a prescription
for treatment, not as an index of malocclusion or an
epidemiologic tool as it was used later by other researchers.
On the basis of the principles developed for defining
and recording individual traits of malocclusion by Björk et
al,4 a simplified method was developed during the years
1969 to 1972 by the working group 2 (WG2) of the FDI
commission on classification and statistics for oral
conditions. During the period 1973 to 1976, the method
was field tested and modified. Final modifications werecarried out by the WG2 in collaboration with the World
Health Organization. The final version of the ‘WHO/FDI
basic method for recording of malocclusion’ was publishedin the bulletin of the World Health Organization in 1979.5
The primary objective of the assessment method was todetermine the prevalence of malocclusion and dental
irregularities and to estimate the treatment needs of a
population, as a basis for the planning of orthodontic
services.
Trends can be identified when reviewing the development of the qualitative methods of recording malocclusion.
Researchers in the earlier days did not define themalocclusion symptoms to be recorded, 6-8 thus,
malocclusion symptoms were recorded in an all-or-none
manner. However, in 1964, Björk, Krebs and Solow4
developed a detailed method to record malocclusion withclearly defined items. The methods developed by the
WHO/FDI 5 also followed the trend of recording
malocclusion symptoms with very carefully defined criteria.

77Anirudh Agarwal, Rinku Mathur
Table 1: Summary of qualitative methods of recording malocclusion
Angle (1899)

Classification of molar relationship devised as a prescription for treatment.

Stallard (1932)

The general dental status, including some malocclusion symptoms, was recorded.
No definition of the various symptoms was specified.

Mc Call (1944)

Malocclusion symptoms recorded include molar relationship, posterior crossbite, anterior crowding,rotated incisors, excessive overbite, open bite, labial or lingual version, tooth displacement,
constriction of arches.
No definition of these symptoms was specified.
Symptoms were recorded in ‘all or none manner’.

Sclare (1945)

Specific malocclusion symptoms were recorded, which include Angle's classification of molar relationship,arch constriction with incisor crowding, arch constriction without incisor crowding, superior protrusion
with incisor crowding, superior protrusion without incisor crowding, labial prominence of canines, linguallyplaced incisors, rotated incisors, crossbite, open bite and closed bite.
No definition of these symptoms was specified.
Symptoms were recorded in ‘all or none manner’.

Fisk (1960)

Dental age was used for grouping patients.
Three planes of space was considered:
1. Anteropostero relationship: Angle’s classification, anterior crossbite, overjet (mm), negative overjet(mm).
2. Transverse relationship: Posterior crossbite (maxillary teeth biting buccally or lingually).
3. Vertical relationship: Open bite (mm), overbite (mm).
Additional measurements include labiolingual spread (Draker, 1960), spacing, therapeutic
extractions, postnatal defects, congenital defects, mutilation, congenital absence, supernumeraryteeth.

Bjork, Krebs andSolow (1964)

Objective registration of malocclusion symptoms based on detailed definitions. Data obtained could
be analyzed by computers.
Three parts:
1. Anomalies in the dentition: Tooth anomalies, abnormal eruption, malalignment of individual teeth.
2. Occlusal anomalies: Deviation in the positional relationship between the upper and lower dental
arches in the sagittal, vertical and transverse plane.
3. Deviations in space conditions: Spacing or crowding.

Proffit and Ackerman (1973) Five steps procedure of assessing malocclusion (no definite criteria for assessment was given):
1. Alignment: Ideal, crowding, spacing, mutilated.
2. Profile: Mandibular prominence, mandibular recession, lip profile relative to nose and chin(convex, straight, concave).
3. Crossbite: Relationship of dental arches in the transverse plane, as indicated by buccolingual
relationship of posterior teeth.
4. Angle's classification: Relationship of the dental arches in the sagittal plane.
5. Bite depth: Relationship of the dental arches in the vertical plane, as indicated by the presence
and absence of anterior open bite, anterior deep bite, posterior open bite and posterior collapsed
bite.
WHO/FDI (1979)

Five major groups of items were recorded (with well-defined recording criteria) as follows:
1. Gross anomalies.
2. Dentition: Absent teeth, supernumerary teeth, malformed incisors, ectopic eruption.
3. Spaced condition: Diastema, crowding, spacing.
4. Occlusion:
A. Incisor segment: Maxillary overjet, mandibular overjet, crossbite, overbite, open bite, midline
shift.
B. Lateral segment: Anteropostero relations, open bite, posterior crossbite.
5. Orthodontic treatment need judged subjectively: Not necessary, doubtful, necessary.

In the earlier methods, only a few malocclusion
symptoms were selected arbitrarily as the items to berecorded.6-8 In the later methods, there was an increasingly
obvious tendency to record items that were logicallygrouped.4,5,9,10
Quantitative Methods of Measuring
Malocclusion and its Severity
Quantitative methods of measuring malocclusion were madesomewhat later than those for qualitative methods. Most of78

the indices for measuring malocclusion severity weredeveloped in the 1950s and 1960s (Table 2).
In 1951, Massler and Frankel11 made the initial attempt
to develop a quantitative method of assessing malocclusion.
The total number of displaced or rotated teeth was the basis
for the evaluation of prevalence and incidence of
malocclusion in population groups.
In 1959, VanKirk and Pennell 12 proposed themalignment index, which involved the grading of tooth
displacement and rotation. They defined quantitatively tooth
JAYPEEWJD
An Overview of Orthodontic Indices
Table 2: Summary of various indices of occlusion
Massler and Frankel (1951)
Malalignment index by
Vankirk and Pennell (1959)
Handicapping labiolingual
deviation index by Braker (1960)
Occlusal feature index by
Poulton and Aaronson (1961)
Malocclusion severity estimate
by Grainger (1960-61)

Occlusal index by Summers (1966)

Treatment priority index by
Grainger (1967)

Handicapping malocclusionassessment record by
Salzmann (1968)

Dental esthetic index (DAI),Cons (1986)

Count the number of teeth displaced or rotated.
Assessment of tooth displacement and rotation is qualitative—all or none.
Tooth displacement and rotations were measured.
Tooth displacement defined quantitatively: Less than 1.5 mm or more than 1.5 mm.
Tooth rotation defined quantitatively: Less than 45° or more than 45°.
Measurements include cleft palate (all or none), traumatic deviations (all or none),
overjet (mm), overbite (mm), mandibular protrusion (mm), anterior open bite (mm) andlabiolingual spread (a measurement of tooth displacement in mm).
Measurements include lower anterior crowding, cuspal interdigitation, vertical overbite andhorizontal overjet.
Occlusal features measured and scored according to defined criteria.
Seven weighted and defined measurements: (1) Overjet, (2) overbite, (3) anterior open bite,(4) congenitally missing maxillary incisors, (5) first permanent molar relationship, (6) posteriorcrossbite and (7) tooth displacement (actual and potential).
Six malocclusion syndromes were defined as follows:
1. Positive overjet and anterior open bite.
2. Positive overjet, positive overbite, distal molar relationship and posterior.
crossbite with maxillary teeth buccal to mandibular teeth.
3. Negative overjet, mesial molar relationship and posterior crossbite with maxillary teeth
lingual to mandibular teeth.
4. Congenitally missing maxillary incisors.
5. Tooth displacement.
6. Potential tooth displacement.
Nine weighted and defined measurements: (1) Molar relation, (2) overbite, (3) overjet,(4) posterior crossbite, (5) posterior open bite, (6) tooth displacement, (7) midline relation,(8) maxillary median diastema, (9) congenitally missing maxillary incisors.
Seven malocclusion syndromes were defined as follows:
1. Overjet and open bite.
2. Distal molar relation, overjet, overbite, posterior crossbite, midline diastema andmidline deviation.
3. Congenitally missing maxillary incisors.
4. Tooth displacement (actual and potential).
5. Posterior open bite.
6. Mesial molar relation, overjet, overbite, posterior crossbite, midline diastema andmidline deviation.
7. Mesial molar relation, mixed dentition analysis (potential tooth displacement) andtooth displacement.
Different scoring schemes and forms for different stages of dental development:
Deciduous dentition, mixed dentition and permanent dentition.
Eleven weighted and defined measurements: (1) Upper anterior segment overjet,(2) lower anterior segment overjet, (3) overbite of upper anterior over lower anterior,(4) anterior openbite, (5) congenital absence of incisors, (6) distal molar relation,(7) mesial molar rotation, (8) posterior crossbite (maxillary teeth buccal to normal),(9) posterior crossbite (maxillary teeth lingual to normal), (10) tooth displacement,(11) gross anomalies.
Seven malocclusion syndromes defined as follows:
1. Maxillary expansion syndrome
2. Overbite
3. Retrognathism
4. Open bite
5. Prognathism
6. Maxillary collapse syndrome
7. Congenitally missing incisors.
Weighted measurements consist of three parts as follows:
1. Intraarch deviation: Missing teeth, crowding, rotations, spacing.
2. Interarch deviation: Overjet, overbite, crossbite, open bite, mesiodistal deviation.
3. Six handicapping dentofacial deformities: (1) Facial and oral clefts, (2) lower lip palatal
to maxillary incisors, (3) occlusal interferences, (4) functional jaw limitation, (5) facial
asymmetry, (6) speech impairment.
This part can only be assessed on live patients.
DAI components include:
1. Number of visible missing teeth (incisors, canines and premolars in maxillary andmandibular arch).

Contd...

World Journal of Dentistry, January-March 2012;3(1):77-86

79Anirudh Agarwal, Rinku Mathur
Contd..
2.
3.
4.
5.
6.
7.
8.
9.
10.

IOTN

Peer assessment rating index(PAR index) Richmond (1992)

Incisal segment crowding
Incisal segment spacing
Midline diastema
Maxillary anterior irregularity
Mandibular anterior irregularity
Maxillary overjet
Mandibular overjet
Vertical anterior open bite
Anteroposterior molar relationship.
It has two components as follows:
A. Dental health component (DHC): has five grades
Grade 1—none: variations in occlusion including displacement less than or equal
to 1 mm.
Grade 2—little
1. Increased overjet greater than 3.5 mm or less than 6 mm with lips competent at rest.
2. Reverse overjet greater than 0 mm but less than or equal to 1 mm.
3. Increased overbite greater than 3.5 mm with no gingival contact.
4. Anterior or posterior crossbite with less than or equal to 1 mm displacement.
5. Small lateral or anterior open bites greater than 1 mm but less than or equal to 2 mm.
6. Prenormal or postnormal occlusions with no other anomalies.
7. Mild displacement of teeth greater than 1 mm but less than or equal to 2 mm.
Grade 3—moderate
1. Increased overjet greater than 3.5 mm but less than or equal to 6 mm withincompetent lips at rest.
2. Reverse overjet greater than 1 mm but less than or equal to 3.5 mm.
3. Increased and complete overbite greater than 3.5 mm with gingival contact but without
indentations or signs of trauma.
4. Anterior or posterior crossbite with less than or equal to 2 mm but greater than 1 mm
displacement between retruded contact position and intercuspal position.
5. Moderate lateral or anterior open bite greater than 2 mm but less than or equal to 4 mm.
6. Moderate displacement of teeth greater than 2 mm but less than or equal to 4 mm.
Grade 4—great
1. Increased overjet greater than 6 mm but less than or equal to 9 mm.
2. Reverse overjet greater than 3.5 mm with no reported masticatory or speech difficulties.
3. Reverse overjet greater than 1 mm but less than or equal to 3.5 mm with reported
masticatory or speech difficulties.
4. Anterior or posterior crossbite with greater than 2 mm displacement between retruded
contact position and intercuspal position.
5. Posterior lingual crossbites with no occlusal contact in one or both buccal segment.
6. Severe displacement of teeth greater than 4 mm.
7. Extreme lateral or anterior open bite greater than 4 mm.
8. Increased and complete overbite causing notable indentations on the palate or labial
gingivae.
9. Patient referred by colleague.
10. Less extensive hypodontia requiring prerestorative orthodontics or orthodontic spaceclosure to obviate the need for a prosthesis (not more than one tooth missing in any quadrant)
Grade 5—Very great
1. Defects of cleft lip and/or palate.
2. Increased overjet greater than 9 mm.
3. Reverse overjet greater than 3.5 mm with reported masticatory and speech difficulties.
4. Impeded eruption of teeth (with exception of 3rd molars) due to crowding,displacement, presence of supernumerary teeth, retained deciduous teeth and anyother pathological cause.
5. Extensive hypodontia with restorative implications (more than 1 tooth missing in any
quadrant) requiring prerestorative orthodontics.
It has 11 components as follows:
1. Upper right segment
2. Upper anterior segment
3. Upper left segment
4. Lower right segment
5. Lower anterior segment
6. Lower left segment
7. Right buccal occlusion
8. Overjet
9. Overbite
10. Centerline
11. Left buccal occlusion.
Contd...

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An Overview of Orthodontic Indices
Contd..
Index of complexity,
outcome and need
(ICON) Richmond (2000)

The occlusal traits scored included:
1. Upper and lower segment alignment.
2. Anterior vertical relationship, centerline, impacted teeth, upper and lower buccal
segment alignment (left and right added together), buccal segment anteroposterior
relationship (left and right added together), buccal segment vertical relationship (leftand right added together), crossbite, missing teeth for any reason (excluding 3rd
molar).
3. Esthetic assessment based on IOTN esthetic component, overjet in mm, reverse
overjet in mm, upper and lower incisor inclination relative to the occlusal plane, overall
upper arch crowding/spacing, lip competency.

displacement and rotation, which was a step forward. The
handicapping labiolingual deviation index (HLDI) was
developed by Draker13 in 1960. Carlos and Ast14 tested theability of the HLDI in distinguishing ‘handicapping’ and‘nonhandicapping’ malocclusions. Clinical judgment madeby orthodontists was used as the standard. The distributionof HLDI scores in the two groups were found to be largely
overlapping, which indicated that the HLDI was unable todistinguish the so-called handicapping malocclusion. The
occlusal feature index was proposed by Poulton and
Aaronson in 1961.15 This index was considered incomplete
since only four features of occlusion were measured andscored (Table 2).

deciduous, mixed and permanent dentition stages) was
therefore developed and different scoring forms were used
for subjects in each stage. The second shortcoming of the
MSE was remedied in the OI by considering the scores ofall syndromes in arriving at the final OI score. The MSE
considered only the score of the syndrome with the highest
score, but in the OI, the other scores were also consideredby adding half of the sum of the remaining scores to thehighest score among the seven syndromes. The third
shortcoming of the MSE was remedied by adjusting fornormality, so that the absence of any occlusal disorder would
be scored as zero.

Malocclusion Severity Estimate (MSE)

Grainger19 in 1967 modified the MSE to develop thetreatment priority index (TPI). Grainger described the index
as a method of assessing the severity of the most common
types of malocclusion and hence, provided a means ofranking patients according to the severity of malocclusion,
the degree of handicap or their priority of treatment.
The prerequisites for determining a handicap were
defined by Grainger19 as follows: (1) Unacceptable esthetics,(2) significant reduction in masticatory function,(3) traumatic condition predisposing to tissue destruction,(4) speech impairment, (5) unstable occlusion and (6) grossor traumatic defects. On the basis of these six prerequisites
for determining a handicap, items to be observed in the TPI
were selected. A few manifestations of malocclusion, suchas midline diastema and slight asymmetry, were rejected as
being of little public health significance. Measurements
could be made either clinically or indirectly from dental
study casts.
In an attempt to revise the MSE, the TPI had corrected
for scoring normalities as zero. However, it had deleted the‘mixed dentition analysis’, which measures potential tooth
displacement. It is also inadequate for assessing theocclusion of the deciduous or mixed dentition. Ghafari
et al20 did a longitudinal evaluation of the TPI. They foundthat TPI was a valid epidemiologic indicator of malocclusion, but TPI values recorded in the transitional dentition
do not predict the future severity of malocclusion in thepermanent dentition.

16

Grainger developed the malocclusion severity estimate(MSE), in the Burlington Research Center, which can beused both on models or on patients. Validity was tested bycomparing the index scores of a study sample with clinicalstandards obtained by having five orthodontists and one
public health dentist array these occlusions according toesthetics, function and treatment difficulty. However, there
were at least three possible shortcomings of the MSE,
namely: (1) The index was derived from data of 12-yearold patients and therefore might not be valid for deciduousand mixed dentitions; (2) the MSE score did not reflect allmeasurements that were accumulated; and (3) the absenceof any occlusal disorder was not scored as zero. The MSE
was later revised, and the revised version was called thetreatment priority index.17
Occlusal Index (OI)
The occlusal index (OI) was developed by Summers in
1966, 18 and was based on the malocclusion severity
estimate, with attempts to remedy its shortcomings. The firstshortcoming of the MSE could be remedied in part bydefining normality over time, in particular equating themixed dentition analysis with actual tooth displacement;
and 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.
World Journal of Dentistry, January-March 2012;3(1):77-86

Treatment Priority Index (TPI)81

Anirudh Agarwal, Rinku Mathur

Handicapping Malocclusion
Assessment Record (HMAR)
In 1968, Salzmann 17 developed the handicapping
malocclusion assessment record (HMAR). The assessment
record forms and the definition of handicapping
malocclusion presented were officially approved by theCouncil on Dental Health of the American Dental
Association, and the Board of Directors of the American
Association of Orthodontists.21
Salzmann’s purpose of developing the HMAR was toprovide a means for establishing priority for treatment ofhandicapping malocclusion. Handicapping malocclusion
and handicapping dentofacial deformity were defined asconditions that constitute a hazard to the maintenance oforal health and interfere with the well-being of the patientby adversely affecting dentofacial esthetics, mandibularfunction or speech. A cut-off point was set at a score so thatthose patients whose scores were above the cut-off point
would be treated by the professional personnel available inthe community, at the same time keeping with the funds
budgeted for orthodontics.
The measurements were made according to the criteria,
and point values were assigned to them. The relative pointvalues, which were based on clinical orthodontic experience,
had been tested by orthodontists from various parts of theUnited States. One important aspect of the HMAR is that itrecords and weighs functional problems, which no otherindex does.
Dental Esthetic Index
The dental esthetic index (DAI) was introduced by Cons in
1987, is based on socially defined esthetic norms. It takes
into consideration, the importance of psychosocial factors
in the assessment of malocclusion and it also assists
professionals in categorizing malocclusion according totreatment needs.22 The relationship between dental esthetics
and psychological and social well-being has been noted bymany investigators. In response to the demand for an
orthodontic index that includes psychosocial criteria inassessing need for orthodontic care and for use inepidemiological surveys, led to the development of thisindex.
The DAI is one such tool which the orthodontist canmake use of in identifying the orthodontic treatment needof the child based on severity, and also provides a single
score linking the public’s perceptions for dental esthetics
with objective measurements associated with malocclusion.
The DAI is particularly sensitive to occlusal conditions thathave the potential for causing psychological or social
dysfunction.

82

The DAI has been integrated into the international
collaboration study of health outcomes by the World HealthOrganization (WHO, 1989) as an international index,
identifies occlusal traits and mathematically derives a single
score.
The DAI links clinical and esthetic components mathematically to produce a single score that combines physicaland esthetic aspects of occlusion, including patient
perceptions.
The score falls between 0 (the most socially acceptable)
and 100 (the least socially acceptable). The DAI score of
36 serves as the cut-off point to differentiate handicappingfrom nonhandicapping malocclusion.
Group Severity Level and Treatment Need23••••

Less than 25: Normal or minor malocclusion—No
treatment need or slight need
26 to 30: Definite malocclusion—treatment elective
31 to 35: Severe malocclusion—treatment highly
desirable
More than 36: Very severe (handicapping) malocclusion—treatment mandatory.

However, DAI has some limitations:
1. The index does not identify cases with deepbite, buccal
crossbite, open bite, midline discrepancy.
2. The DAI had been developed as a screening tool forpermanent dentitions; it might be unsuitable during themixed dentition stage accompanied with changes infuture dental appearance.22
3. Since, DAI was developed to determine severity of
malocclusion and relative need for publicly subsidized
orthodontic treatment based on perceptions of dental
esthetics by US students; hence the cut-off score fordifferent ethnic groups may have to be established.
4. DAI measurements are made using a millimeter gauge,
and small errors in accuracy can have an exaggerated
effect because of the index weightings.22
Advantages
1. The DAI considers patients’ perceptions regarding
orthodontic treatment, as it is the patients who receive
treatment and need to gain satisfaction from improved
esthetics and function.
2. DAI can be effectively used on a prospective basis to
identify the need for orthodontic treatment
quantitatively.
3. It can be used directly in the patients’ mouth.
4. Dental auxiliaries can be trained to use it to reduce costand burden on dentists.
5. Can be used to assess the treatment standards although
it was not developed for such use.

JAYPEEWJD
An Overview of Orthodontic Indices

Index of Orthodontic Treatment Need (IOTN)

Esthetic Component

After reviewing the available literature, Peter Brook andWilliam Shaw24 (1989) felt that malocclusion could be best
quantitatively measured by using two separate components
to record firstly the dental health and functional indications
for treatment and secondly the esthetic impairment causedby the malocclusion.

The second part of the overall assessment is to record theesthetic impairment contributed by malocclusion. This scale
was constructed using dental photographs of 1000, 12-yearold collected during a large multidisciplinary survey. Six
nondental judges rated these photographs on a visual analog
scale, and gave a 10-point scale (Fig. 1) from 0.5 (attractive
dental appearance) to 5.0 (unattractive dental appearance).

Dental Health Component
The index of treatment priority used by the Swedish Dental
Board25 (Linder-Aronson, 1974) was used as the basis forgrading the functional and dental health indications fortreatment. There are 5 grades, grade 1 representing little orno need for treatment and grade 5 representing great needfor treatment (Table 3). Values for cut-off points between
grades for each occlusal trait that represents a quantifiablethreat to the dentition were established.

Peer Assessment Rating Index (PAR Index)
The peer assessment rating index (PAR) was introduced by
Richmond in 1992. The PAR index is a quantitative,
objective method for measuring malocclusion and theefficacy of orthodontic treatment. The PAR index provides
a single score, based on a series of measurements, that
represents the degree to which a case deviates from normal

Table 3: Dental health component of IOTN
Grade 1None
• Variations in occlusion including displacement less than or equal to 1 mm.

Grade 2

Little1. Increased overjet greater than 3.5 mm or less than 6 mm with lips competent at rest
2. Reverse overjet greater than 0 mm but less than or equal to 1 mm.
3. Increased overbite greater than 3.5 mm with no gingival contact.
4. Anterior or posterior crossbite with less than or equal to 1 mm displacement.
5. Small lateral or anterior open bites greater than 1 mm but less than or equal to 2 mm
6. Prenormal or postnormal occlusions with no other anomalies.
7. Mild displacement of teeth greater than 1 mm but less than or equal to 2 mm.

Grade 3Moderate
1. Increased overjet greater than 3.5 mm but less than or equal to 6 mm with incompetent lips at rest.
2. Reverse overjet greater than 1 mm but less than or equal to 3.5 mm.
3. Increased and complete overbite greater than 3.5 mm with gingival contact but without indentations or signs of trauma.
4. Anterior or posterior crossbite with less than or equal to 2 mm but greater than 1 mm displacement between
retruded contact position and intercuspal position.
5. Moderate lateral or anterior open bite greater than 2 mm but less than or equal to 4 mm.
6. Moderate displacement of teeth greater than 2 mm but less than or equal to 4 mm.

Grade 4Great
1. Increased overjet greater than 6 mm but less than or equal to 9 mm.
2. Reverse overjet greater than 3.5 mm with no reported masticatory or speech difficulties.
3. Reverse overjet greater than 1 mm but less than or equal to 3.5 mm with reported masticatory or speech difficulties.
4. Anterior or posterior crossbite with greater than 2 mm displacement between retruded contact position andintercuspal position.
5. Posterior lingual crossbites with no occlusal contact in one or both buccal segment.
6. Severe displacement of teeth greater than 4 mm.
7. Extreme lateral or anterior open bite greater than 4 mm.
8. Increased and complete overbite causing notable indentations on the palate or labial gingivae.
9. Patient referred by colleague.
10. Less extensive hypodontia requiring prerestorative orthodontics or orthodontic space closure to obviate the needfor a prosthesis (Not more than 1 tooth missing in any quadrant).

Grade 5

Very great
1. Defects of cleft lip and/or palate.
2. Increased overjet greater than 9 mm
3. Reverse overjet greater than 3.5 mm with reported masticatory and speech difficulties.
4. Impeded eruption of teeth (with exception of 3rd molars) due to crowding, displacement, presence ofsupernumerary teeth, retained deciduous teeth and any other pathological cause.
5. Extensive hypodontia with restorative implications (more than 1 tooth missing in any quadrant) requiring
prerestorative orthodontics.

World Journal of Dentistry, January-March 2012;3(1):77-86

83Anirudh Agarwal, Rinku Mathur

Fig. 1: Esthetic component of IOTNalignment and occlusion. This index is a valid and reliable
tool for measuring malocclusion on plaster models andpatients. The average time to record the PAR index score isapproximately 5 minutes.
In orthodontics, it is important to objectively assess
whether a worthwhile improvement has been achieved interms of overall alignment and occlusion for an individual
patient. This can be evaluated by a reduction in the PAR
index score.
Index of Complexity, Outcome and Need (ICON)
The index of complexity, outcome and need (ICON), wasdeveloped by Richmond and Daniels in 2000,26 with anobjective to assess treatment need, complexity, treatment84

improvement and outcome based on international
orthodontic professional opinion, intended for use in thecontext of specialist practice. Such an index would serve asa means to compare treatment thresholds in different
countries and serve as a basis for quality assurance standards
in orthodontics. It was intended to be a single index forassessing treatment inputs and outcomes. An international
panel of 97 orthodontists gave subjective judgments on theneed for treatment, treatment complexity, treatment
improvement and acceptability on a diverse sample of 240
initial and 98 treated study models. The index is intended
for use in late mixed dentition onwards, because transitional
stages during the early and middle mixed dentitions are
difficult to assess for esthetics.

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An Overview of Orthodontic IndicesThis index has been designed specifically to enableassessments of treatment need and outcome using one setof occlusal traits, and for this reason may offer clear
advances on the currently used methods. The practicalapplication of the index is relatively simple and having
relatively few traits to measure which is reliable and easy
to apply, to study models or clinically. Application of theindex takes approximately 1 minute for each case andtherefore is relatively quick. It requires no measurement
tools other than an ordinary millimeter rule and an esthetic
component scale (Shaw et al, 1991). The index is valid forboth treatment need, complexity and outcome assessments
in as much as it represents a broadly based international
body of expert opinion in orthodontics.26
DISCUSSION
Over the years various studies21,27-29 have compared IOTN
and the DAI, both include two components, anatomic andesthetic measuring many of the same traits. These include
overjet, reverse overjet, open bite, displacements andmissing teeth. However, the importance of missing teeth
trait is rated differently by each index. One missing toothin the dental health component of the IOTN, if judged theworst trait, is given a grade of 3 on the revised IOTN scale,indicating ‘definite need’ for treatment. In contrast, in the
DAI one missing tooth is given a weight of six. If a missing
tooth was the only trait recorded on a person, the weight ofsix would be multiplied by one and added to the constantnumber 13 to give a DAI score of only 19. This score would
be judged by the DAI as not requiring orthodontic treatment
or as having only a slight need.
In the IOTN, the esthetic component is a separate
instrument from the dental health component. The IOTN inboth its dental health and esthetic components uses only
three grades, ‘no need’, ‘borderline need’, and ‘definite
need’. A scale with only three grades lacks the ability torank order cases with greater or lesser need for treatment
within grades.
The advantage of the DAI is that perceptions of esthetics
are linked with anatomic trait measurements to produce asingle score, obviating the need for two separate instrumentsthat cannot be combined as in the IOTN and scores can berank ordered on a continuous scale and can differentiatecases within severity levels.28
Brook and Shaw4 state that the true validation of the
IOTN must await the emergence of further research data.
Several studies show the validity of the DAI.22,28-32 The
DAI scores are significantly associated with perception ofneed for treatment by students and parents,28 and they aregood predictors of the receipt of future fixed orthodontic
treatment.12
Another study compared DAI with handicapping
labiolingual deviations index with the California
World Journal of Dentistry, January-March 2012;3(1):77-86

modification [HLD (CalMod)] and IOTN, and found all thethree indexes to be valid measures of treatment need asperceived by orthodontists and did not find any significant
difference between them.30
CONCLUSION
Each index and method of the assessment described earlier
was based on the opinion of an individual or a group ofindividuals. There are bound to be disagreement among
other professionals as to the validity of a particular method.
It had been widely agreed that no particular index or method
available that are truly inclusive of all recommended criteria.
Therefore, different indices or method had been developed
according to different requirements. Given the above, it may
be necessary to use more than one index in order to gather
information to suit the objective of the particular study.
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ABOUT THE AUTHORS
Anirudh Agarwal
Professor and Head, Department of Orthodontics, Rajasthan Dental
College and Hospital, Jaipur, Rajasthan, India

Rinku Mathur
Assistant Professor, Department of Pedodontics and Preventive
Dentistry, Government Dental College and Hospital, Jaipur, Rajasthan
India

CORRESPONDING AUTHOR
Anirudh Agarwal, Professor and Head, Department of Orthodontics,
F-25, 4th Avenue, Lal Bahadur Nagar (West), JLN Marg, Jaipur-302018,
Rajasthan, India, Phone: 09414065588, e-mail:docanirudh@ yahoo.com

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