Orthodontic indices are one of the tools that are available for orthodontists to grade and assess malocclusion. Orthodontic indices can be useful for an epidemiologist to analyse prevalence and severity of malocclusion in any population.
Angle's classification
Angle's Classification is devised in 1899 by father of Orthodontic, Dr Edward Angle to describe the classes of malocclusion, widely accepted and widely used since it was published. Angle's Classification is based on the relationship of the mesiobuccal cusp of the maxillary first molar and the buccal groove of the mandibular first molar. Angle's Classification describes 3 classes of malocclusion:
Class I: The molar relationship of the occlusion is normal or as described for the maxillary first molar, with malocclusion confined to anterior teeth Class II: The retrusion of the lower jaw with distal occlusion of the lower teeth (or in other words, the maxillary first molar occludes anterior to the buccal groove of the mandibular first molars) Class II div 1: class II relationship with proclined upper central incisors (overjet) Class II div 2: class II relationship with lingual inclination of upper central incisors (retrocline) and upper lateral incisors overlapping the centrals Class III: The protrusion of the lower jaw with mesiobuccal cusp of maxillary first molar occluding posterior to the buccal groove of the mandibular first molar, with lingually inclined lower incisors and cuspids
Angle's classification only considers anteroposterior deviations in the sagittal plane while malocclusion is a three dimensional problem (sagittal, transverse and vertical) rather than two dimensional as described in Angle's classification. Angle's classification also disregards the relationship of the teeth to the face.
Massler and Frankel's index recording the number of displaced/rotated teeth Introduced in 1951 by Massler & Frankel to produce a way to record the prevalence of malocclusion which will satisfy 3 criteria: simple, accurate and applicable to large groups of individual; yield quantitative information that could be statistically analysed; reproducible so that results are comparable. This index uses individual teeth as unit of occlusion instead of a segment of the arch. Each tooth is examined to determine whether it is in correct occlusion or it is maloccluded.MASSLER, M.; FRANKEL, J. M. Prevalence of malocclusion in children aged 14 to 18 years. American Journal of Orthodontics, v. 37, n. 10, p. 751-768, 1951/10/01 1951. ISSN 0002-9416. < http://www.ajodo.org/article/0002941651900474/abstract > < http://www.ajodo.org/article/0002941651900474/fulltext > < http://www.ajodo.org/article/0002941651900474/pdf >.
The total number of maloccluded teeth is the counted and recorded. Each tooth is examined from two different aspects: occlusal aspect and then the buccal and labial surfaces with the exclusion of third molars. Tooth that is not in perfect occlusion from both occlusal aspect (in perfect alignment with contact line) and buccal aspect (in perfect alignment with plane of occlusion and in correct interdigitation with opposing teeth) is considered as maloccluded. Each maloccluded tooth is given a value of 1 while tooth in perfect occlusion is given a score of 0. A score of 0 will indicate a perfect occlusion; score of more than 10 would be classified as sufficient severity that would require orthodontic treatment; score between 1 and 9 would be classified as normal occlusion in which no orthodontic treatment is indicated.
However, while this index is simple, easy and able to provide prevalence and incidence data in populations group, there are some major disadvantage with this index: primary dentition, erupting teeth and missing teeth are left out in the scoring system and difficulties in judging conformity of each tooth to an ideal position in all planes.OTUYEMI, O. D.; JONES, S. P. Methods of assessing and grading malocclusion: a review. Aust Orthod J, v. 14, n. 1, p. 21-7, Oct 1995. ISSN 0587-3908 (Print)0587-3908.
Malalignment Index Introduced in 1959 by Lawrence Vankirk and Elliott Pennell. This index requires the use of a small plastic, gauge-like tool designed for assessment. Tooth rotation and displacement are measured.
The mouth is divided into 6 segments, and is examined in the following order: maxillary anterior, maxillary right posterior, maxillary left posterior, mandibular anterior, mandibular right posterior and mandibular left posterior. The tool is superimposed over the teeth for the scoring measurement, each tooth present is scored 0, 1 or 2.
2 types of malalignment are being measured, rotation and displacement. Rotation is defined as the angle formed by the line projected through contact areas of observed tooth and the ideal arch line. Displacement is defined as both of the contact areas of the tooth are displaced in the same direction from the ideal alignment position.
Score of 0 represents ideal alignment with no apparent deviation from the ideal arch line. Score of 1 represents minor malalignment: rotation of less than 45º and displacement of less than 1.5mm Score of 2 represents major malalignment: rotation of more than 45º and displacement of more than 1.5mm
Handicapping Labiolingual Deviation Index (HLDI) This index was proposed in 1960 by Harry L. Draker. HLDI was designed for identification of dento-facial handicap. The index is designed to yield prevalence data if used in screenings. Measurement taken are as following: cleft palate (all or nothing), severe traumatic deviation (all or none), overjet (mm), overbite (mm), mandibular protrusion (mm), anterior open bite (mm), labiolingual spread (measurement of tooth displacement in mm) HLD index is used in several states in the United States, with some modifications to its original form by the states that used them for determining orthodontic treatment need.
Occlusal feature index Occlusal Feature Index is introduced by Poulton and Aaronson in 1961. The index is based on four primary features of occlusion that is important in orthodontic examination. The four primary features are as following:
Lower anterior crowding (canine to canine area) Posterior cuspal interdigitation (right posterior premolar to molar area) Vertical overbite (measured by portion of lower incisor covered by upper central incisors when in occlusion) Horizontal overjet (measured between the labial surface of upper incisor to labial surface of lower incisor)
Occlusal Feature Index recognises malocclusion is a combination of the way teeth occlude as well as the position of the teeth relative to the neighbouring teeth. However, the scoring system is not sensitive enough for case selection for orthodontic purposes.
Malocclusion Severity Estimate (MSE) Introduced in 1961 by Grainger. MSE measured 7 weighted and defined measurement:
Overjet Overbite Anterior open bite Congenitally missing maxillary incisors First permanent molar relationship Posterior cross bite Tooth displacement (actual and potential)
MSE defined and outlined 6 syndromes of malocclusion:
Positive overjet and anterior open bite Positive overjet, positive overbite, distal molar relationship and posterior crossbite with maxillary teeth buccal to mandibular teeth. Negative overjet, mesial molar relationship and posterior crossbite with maxillary teeth lingual to mandibular teeth Congenitally missing maxillary incisors Tooth displacement Potential tooth displacement
Despite being a relative comprehensive definition, there are a few shortcomings of this index, namely: the data is derived from a 12 years old patients hence might not be valid for deciduous and mixed dentitions, the score does not reflect all the measurement that were taken and accumulated and the absence of any occlusal disorder is not scored as zero. Grainger then revised the MSE index and published the revised version in 1967 and renamed the index to Treatment Priority Index (TPI).
Occlusal Index (OI) Occlusal Index was developed by Summers in his doctoral dissertation in 1966, and the final paper was published in 1971. Based on Malocclusion Severity Estimate (MSE), OI attempted to overcome the shortcoming of the MSE.
Summers devised different scoring scheme for deciduous, mixed and permanent dentition with 6 predefined stages of dental age:
Dental age 0 begins at birth, ending with the eruption of first deciduous tooth. Dental age 1 begins when stage 0 ended, ending with all deciduous teeth are in occlusion. Dental age 2 begins when stage 1 ended, ends with the eruption of first permanent tooth. Dental age 3 begins when stage 2 ended and ends with all the permanent central, lateral incisors and first permanent molar are in occlusion. Dental age 4 begins when stage 3 ended and ends with the eruption of any permanent canines or premolar. Dental age 5 begins when stage 4 ended and ends with all permanent canines and premolar are in occlusion. Dental age 6 begins when all permanent canines and premolar are in occlusion.
Nine weighted and defined measurement being taken:
Molar relation Overbite Overjet Posterior crossbite Posterior open bite Tooth displacement Midline relation Maxillary median diastema Congenitally missing maxillary incisors
Summers also defined 7 malocclusion syndromes which includes:
Overjet and openbite Distal molar relation, overbite, overjet, posterior crossbite, midline diastema and midline deviation Congenitally missing maxillary incisors Tooth displacement (actual and potential) Posterior open bite Mesial molar relation, overjet, overbite, posterior crossbite, midline diastema and midline deviation Mesial molar relation, mixed dentition analysis (potential tooth displacement) and tooth displacement.
Grade Index Scale for Assessment of Treatment Need (GISATIN) Grade Index Scale for assessment of treatment need (GISATN) was created by Salonen L in 1966. GISATN grades the type and severity of the malocclusion, however, the index doesn't indicate or describe the damage each type of occlusion can cause.
Treatment Priority Index (TPI) Treatment priority index (TPI) was created in 1967 by R.M. Grainger in Washington D.C United States. Grainger described the index as “a method of assessing the severity of the most common types of malocclusion, the degree of handicaps or their priority of treatment”. In the index there are eleven weighed and defined measurements which are: upper anterior segment overjet, lower anterior segment overjet, overbite of upper anterior over lower anterior, anterior open bite, congenital absence of incisors, distal molar relation, mesial molar relation, posterior crossbite (buccal), posterior crossbite (lingual), tooth displacement, gross anomalies. It also includes the seven maloclussion syndromes: maxillary expansion syndrome, overbite, retrognathism, open bite, prognathism, maxillary collapse syndrome and congenitally missing incisors.
Handicapping Malocclusion Assessment Record (HMAR) Handicapping malocclusion assessment record (HMAR) was created by Salzmann JA in 1968. It was created to establish needs for treatment of handicapping malocclusion according to severity presented by magnitude of the score when assessing the malocclusion. The assessment can be made either directly from the oral cavity or from available casts. To make the assessment more accurate an additional record form is made for direct mouth assessment which allows the recording and scoring of mandibular function, facial asymmetry, lower lip malposition in relation to the maxillary incisor teeth and desirability of treatment. The index has been accepted as a standard by the Council or Orthodontic Health Care, the Board of Directors of the American Association due to the easy use of HMAR.
Little's Irregularity Index (LII)