Index of Orthodontic Treatment Need

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The Index of Orthodontic Treatment Need ( IOTN ), German index of the need for orthodontic treatment , indicates the need for treatment in the event of misaligned teeth.

Creation of the IOTN

The IOTN was published in 1989 by Peter Brook and William Shaw under the name “Index of orthodontic treatment priority” in Great Britain. The authors used the findings from earlier work, in particular by A. Björk, A. Krebs and B. Solow (regarding the methodology for serial examinations for tooth misalignments), from S. Linder-Aronson (regarding comparative orthodontic examinations in Sweden) and from M Evans and W. Shaw (on comparative aesthetic examinations of misaligned teeth).

The purpose of the IOTN was to standardize and harmonize the assessment of the need for orthodontic treatment between the individual orthodontists or treatment centers, especially in light of the fact that the financing of such treatments in Great Britain was largely publicly funded. The IOTN is less suitable for assessing the quality of the results of orthodontic treatment. The PAR index published in 1992 was developed for this purpose . The use of the IOTN was scientifically monitored in Great Britain: In 1992 a comprehensive publication by S. Richmond, K. O'Brien, I. Buchanan and D. Burden appeared. In 2005, Stephen Richmond, Professor of Public Dental Health at the University of Cardiff, published another summary of the IOTN, the PAR index and other orthodontic indices.

In Germany , the IOTN served as the basis for developing the system of '' 'Orthodontic Indication Groups' '' that have been in use since 2002.

In Austria , the use of the IOTN has been mandatory since July 1, 2015 to assess the need for orthodontic treatment as a relevant index for the reimbursement of treatment costs by the social insurance . In the summer of 2017, a number of changes were made to the IOTN in a contractual agreement between the then Main Association of Social Insurance Institutions (since January 1, 2020: umbrella association of social insurance institutions ) and the Austrian Dental Association . This created an independent Austrian variant of the IOTN, which has been binding for the remuneration of orthodontic treatments within the Austrian social security system since September 1, 2017.

Structure of the IOTN

The IOTN consists of two components:

  1. Aesthetic component : The aesthetic component consists of 10 photos of the teeth taken from anteriorly with differently attractive tooth positions, with photo no. 1 showing the most attractive and photo no. 10 the least attractive. The aesthetic component is determined by comparing the photos with the teeth of a patient to be examined.
  2. Dental health component (Dental Health Component): In this component, the malocclusion is in five grades divided.
  • Grade 1: no need for treatment
  • Grade 2: low need for treatment
  • Grade 3: moderate need for treatment
  • Grade 4: great need for treatment
  • Grade 5: very great need for treatment

The specific deformity present is assessed on the basis of 15 qualifying features (qualifiers). A letter is assigned to each of these characteristics:

Assessment of the qualifications of the dental health component

The individual qualifications of the dental health component of the IOTN are assessed. Both measurements on the dentition or tooth model and clinical assessments are included in the assessment. Measurements can be carried out with suitable measuring instruments (narrow ruler, periodontal probe, measuring cross) on the patient or on a physical tooth model, or with digital measurement programs on virtual tooth models. Anamnesis and clinical examinations must be performed on the patient by the orthodontist.

Feature a - positive sagittal overbite

The size of the sagittal step in the area of ​​the incisors is measured. Only permanent teeth are counted. Special features of the Austrian IOTN variant are listed below.

  • IOTN value 2a:> 3.5mm but ≤6mm with competent lip closure
  • IOTN value 3a:> 3.5mm but ≤6mm with incompetent lip closure
  • IOTN value 4a:> 6mm but ≤9mm
  • IOTN value 5a:> 9mm

Characteristic b - wrong sagittal overbite without chewing or speech problems

The size of the inverted sagittal step in the area of ​​the incisors is measured. Only permanent teeth are counted. All four upper incisors must be in the wrong overbite. Special features of the Austrian IOTN variant are listed below.

  • IOTN value 2b:> 0mm but ≤1mm
  • IOTN value 3b:> 1mm but ≤3.5mm without chewing or language problems
  • IOTN value 4b:> 3.5mm without chewing or language problems

Characteristic c - cross bite

The crossbite is assessed in the area of ​​teeth 1 to 7, which also includes scissor bite, square bite and cusp-cusp teeth. The decisive factor for the evaluation is the discrepancy between the retral contact position and the intercuspid position caused by the crossbite, i.e. the forced bite caused by the crossbite (RKP / ICP discrepancy). This can be caused by permanent teeth or milk teeth.

  • IOTN value 2c: RKP / IKP discrepancy ≤1mm
  • IOTN value 3c: RKP / IKP discrepancy> 1mm but ≤2mm
  • IOTN value 4c: RKP / IKP discrepancy> 2mm

Feature d - contact point shift

It is measured how much the anatomical contact points of neighboring teeth are shifted against each other (contact point shift, KPV). The vertical component of the shift is not counted. Only permanent teeth are counted, the measuring range includes all teeth from 1 to 8. Special features of the Austrian IOTN variant are listed below.

  • IOTN value 2d: KPV> 1mm but ≤2mm
  • IOTN value 3d:> 2mm but ≤4mm
  • IOTN value 4d:> 4mm

Characteristic e - open bite

The vertical distance between antagonistic teeth is measured (cutting edge to cutting edge or chewing surface to chewing surface). Only permanent teeth are counted, the measuring range includes teeth 1 to 7. Special features of the Austrian IOTN variant are listed below.

  • IOTN value 2e: open bite> 1mm but ≤2mm
  • IOTN value 3e: open bite> 2mm but ≤4mm
  • IOTN value 4e: open bite> 4mm

Feature f - deep bite

The extent to which antagonistic incisors are covered is assessed. Only permanent teeth are counted, the measuring range includes the incisors. Deviations in the Austrian IOTN variant are listed below.

  • IOTN value 2f: deep bite with overlap of an antagonistic incisor> 3.5mm
  • IOTN value 3f: Deep bite with contact with the antagonistic palatal or labial gingiva
  • IOTN value 4f: deep bite with traumatic bite of the antagonistic palatal or labial gingiva

Feature g - good occlusion

An assessment is made of whether there is an unclean sagittal relationship in the otherwise missing malocclusions in the posterior region. Only permanent teeth are counted.

  • IOTN value 2 g: deviation of no more than half a premolar width in the sagittal relation

Feature h - hypodontia

The non-abutment of permanent teeth 1 to 7 is assessed.

  • IOTN value 4h: failure to create no more than one tooth per quadrant
  • IOTN value 5h: failure of more than one tooth in at least one quadrant

Feature i - impacted tooth

Impacted and retained teeth 1 to 7 are assessed. As soon as part of the tooth has broken through the gingiva (is visible), the characteristic “i” can no longer be assessed.

  • IOTN value 5i: hindrance of proper tooth eruption due to one of the following causes:
    • Lack of space (gap ≤4mm, support zone in the upper jaw ≤18mm, support zone in the lower jaw ≤17mm)
    • Displacement (ectopic position)
    • Prevention of eruption due to a surplus tooth, mesiode, odontoma
    • Prevention of eruption due to a persistent milk tooth
    • Another pathological cause

Feature l - posterior lingual crossbite

An assessment is made of whether there is a scissor bite in the side tooth segment on one or both sides. Only permanent teeth in the range 4 to 7 are scored. All existing teeth in this area must be in the scissor bite.

  • IOTN value 4l: scissor bite without functional occlusal contact in the entire posterior segment on one or both sides

Feature m - wrong sagittal overbite with chewing or language problems

The size of the inverted sagittal step in the area of ​​the incisors is measured. Only permanent teeth are counted. All four upper incisors must be in the wrong overbite. Special features of the Austrian IOTN variant are listed below.

  • IOTN value 4 m:> 1mm but ≤3.5mm with chewing or language problems
  • IOTN value 5 m:> 3.5 mm with chewing or language problems

Characteristic p - cleft lip and palate

An assessment is made of whether there are cleft lip and palate that affect the position of the teeth.

  • IOTN value 5p: defects such as cleft lip and palate with effects on the position of the teeth

Feature s - sunken milk teeth

Infra-occlusal deciduous teeth are assessed.

  • IOTN value 5s: sunken milk teeth that have one of the two conditions:
    • either only two bumps remain visible
    • or the neighboring teeth are strongly tilted over the milk tooth

Characteristic t - partially erupted teeth, tilted and impacted against neighboring teeth

Partially retained permanent teeth that have tilted against permanent teeth are assessed. The measuring range covers teeth 1 to 8. Special features of the Austrian IOTN variant are listed below.

  • IOTN value 4t: Partially broken tooth, tilted towards the neighboring tooth.

Feature x - excess teeth

Surplus permanent teeth are assessed, the measuring range includes teeth 1 to 7. The tooth does not have to have erupted.

  • IOTN value 4x: Surplus permanent tooth, after the removal of which the dental arch must be formed or a gap must be closed.

Determination of the IOTN value

Evaluation of the aesthetic component

The need for treatment results from the aesthetic component by comparing the patient's appearance with the reference photos. Photos 1 to 4 indicate that there is at most a minor need for treatment. Photos 5 to 7 indicate moderate to marginal treatment needs. Photos 8 through 10 indicate orthodontic treatment needs.

Ranking of the characteristics of the dental health component using the MOCDO scheme

In the dental health component of the IOTN, only a single value is given , namely the highest diagnosable value. This results first from the highest degree, which determines the need for treatment. If there are several qualifications that meet the highest level (for example IOTN 4a and IOTN 4h), these are determined according to a method developed by Richmond et al. specified hierarchical scheme, the so-called MOCDO scheme.

The qualifications are divided into 6 groups.

  • M issing teeth (missing teeth): Characteristics i and h
  • O verjet / reverse overjet (pos./neg. Sagittal overbite): features a, b, m
  • C rossbite (crossbite): characteristic c
  • D isplacement: feature of d
  • O verbite / open bite: features e and f
  • Others: features g, l, p, s, t, x

The acronym "MOCDO" results from the English first letters of the first 5 groups. In terms of hierarchy, the groups above and the qualifications listed in them are superordinate to the groups below. For example, an IOTN feature 4h is superordinate to feature 4a, the IOTN value to be correctly indicated is therefore 4h.

Special features and deviations of the IOTN in Austria

As a result of the contractual agreement on the IOTN concluded in the summer of 2017 between the then Main Association of Social Insurance Institutions (since January 1, 2020: Umbrella Association of Social Insurance Institutions) and the Austrian Dental Association , some changes have been made through which an independent Austrian variant of the IOTN has been created.

Elimination of the aesthetic component

The aesthetic component is not taken into account for orthodontic treatments within the Austrian social insurance system

Special features of characteristics a, b and m in Austria

In Austria, the greatest distance between two antagonistic incisors is always measured, regardless of whether the measurement is based on the furthest labial incisor or not. In the original IOTN, however, measurements are always taken from the incisor that is furthest labial.

Special features of feature d in Austria

In the Austrian variant, it is more clearly regulated than in the original IOTN how to evaluate contact point shifts in the case of gapped teeth and rotated teeth:

In Austria, tooth gaps are also measured, unless the neighboring teeth are completely correct in the dental arch and show no deviation from the dental arch.

Contact point shifts are also measured in the usual way with tooth rotations, only with rotated premolars which (apart from the rotation) do not deviate from the dental arch and whose rotation does not cause any interference to antagonists in the sense of a cross or head bite, are not taken into account.

Special features of the feature e in Austria

In the Austrian variant, the open bite in the posterior region is measured from cusp to cusp, while the original IOTN refers to the "greatest distance" (which corresponds to a cusp-fossa or fossa-fossa distance).

Special features of the feature f in Austria

In the Austrian variant, the deep bite is not measured on the incisors (2 to 2), as in the original IOTN, but on the front teeth (incisors and canines, 3 to 3).

Special features of the characteristic t in Austria

In the Austrian variant, a multi-bracket treatment must be required for the treatment of a partially retained tooth in order to be rated as 4t. If a partially retained six-year-old molar tilts against a second deciduous molar and leads to an undermining resorption of this deciduous tooth, this can also be rated as IOTN 4t.

Commitment to digitization

In communication between orthodontists and social security, all documents must be transmitted digitally after a transition period planned until the end of 2021. To measure virtual tooth models, their digital measurement is therefore necessary. For the Austrian market, suitable modules of the OnyxCeph³ measurement program from Image Instruments GmbH, Niederwaldstraße 3, D-09123 Chemnitz, which meets the requirements for digital measurement of the Austrian variant of the IOTN and the PAR index, were developed together with the Association of Austrian Orthodontists .

literature

  • Gabriele Watzer, Armin Watzer: IOTN and PAR-Index in Austria - manual for correct and correct use . Published by the Association of Austrian Orthodontists, 2020. ISBN 978-3-9519790-0-7
  • Stephen Richmond: Evaluating Effective Orthodontic Care . First Numerics Ltd., Cardiff, 2005, Reprint 2014. ISBN 0-9549670-1-1 .

Individual evidence

  1. ↑ Brook, PH and Shaw, WC. The Development of an Index of Orthodontic Treatment Priority. European Journal of Orthodontics. 1989, Vol. 11, pp. 309-320.
  2. ↑ Björk, A, Krebs, AA and Solow, B. A Method for Epidemiological Registration of Malocclusion. Acta odontologica Scandinavica. 1964, pp. 27-41
  3. ^ Linder-Aronson, St. Orthodontics in the Swedish Public Health Service. European Journal of Orthodontics. 1974, Vol. 29 (Suppl 1), pp. 233-240.
  4. ↑ Evans, MR and Shaw, WC. Preliminary evaluation of an illustrated scale for rating dental attractiveness. European Journal of Orthodontics (9). 1987, pp. 314-318
  5. ↑ Richmond, S, Shaw, WC, O'Brien, KD, Buchanan, IB, Jones, R, Stephens, CD, Roberts, CT and Andrews, M. The development of the PAR Index (Peer Assessment Rating): reliability and validity . European Journal of Orthodontics. April 1992, Vol. 14, 2, pp. 125-139.
  6. ↑ Richmond, S, Shaw, WC, Roberts, CT and Andrews, M. The PAR Index (Peer Assessment Rating): methods to determine outcome of orthodontic treatment in terms of improvement and standards. European Journal of Orthodontics. June 1992, Vol. 14, 3, pp. 180-187.
  7. ↑ Richmond, S, O'Brien, KD, Buchanan, IB and Burden, D. An Introduction to Occlusal Indices. Mandent Press. 1992, reprint 1994
  8. ^ Richmond, S. Evaluating Effective Orthodontic Care. S. l. : First Numerics Ltd., Cardiff, 2005, Reprint 2014. ISBN 0-9549670-1-1 .
  9. ↑ Schopf, P. Orthodontic accounting. Quintessenz, Berlin, 2nd edition 2013. ISBN 978-3-86867-188-9 .
  10. ↑ General orthodontic contract for services according to § 153a ASVG (§ 94a GSVG, § 95a BSVG, § 69a B-KUVG) and the guideline tariff according to § 343c ASVG, concluded between the Austrian Chamber of Dentists and the main association of social insurance institutions . 2015.
  11. ↑ Official announcement of the Austrian social insurance (Hauptverband) No. 66/2015, 7th amendment to the model statute 2011. 2015.
  12. ↑ Joint determination between the Austrian Dental Association and the Main Association of Social Insurance Institutions on the IOTN from August 16, 2017. [Online] 2017. https://www.zahnaerztekammer.at/fileadmin/user_upload/IOTN-Vereinigung_HV-OEZAEK_010917.pdf .
  13. ↑ Watzer, A and Watzer, G. How common are non-placement of wisdom teeth in patients with hypodontia? - A retrospective study. Orthodontics. 2009, Vol. 23 (3), pp. 205-213.
  14. ↑ Evans, MR and Shaw, WC. Preliminary evaluation of an illustrated scale for rating dental attractiveness. European Journal of Orthodontics (9). 1987, pp. 314-318.
  15. ↑ Richmond, S, O'Brien, KD, Buchanan, IB and Burden, D. An Introduction to Occlusal Indices. Mandent Press. 1992, reprint 1994
  16. ↑ Watzer, G and Watzer, A: IOTN and PAR index in Austria - manual for the correct and proper application. Published by the Association of Austrian Orthodontists, 2020. ISBN 978-3-9519790-0-7