Key Points
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This paper investigates a new orthodontic occlusal index, the Index of Outcome, Complexity and Need (ICON). It suggests that this single index can replace the PAR index and the Index of Orthodontic Treatment Need (IOTN). The implications are:
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The single index (ICON) which is easier to learn and use than PAR and IOTN could measure orthodontic treatment need and treatment standards.
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The index could be easily incorporated into the orthodontic assessment of a patient in general dental practice. The inclusion of IOTN in the general dental services has been proposed. ICON would be quicker to learn, apply and more information could be gleaned than just treatment need.
Abstract
Aim To evaluate any relationship between ICON, IOTN and PAR. To establish whether or not ICON could replace these indices as a measure of orthodontic treatment complexity, outcome and need.
Method The study models of 55 consecutively treated cases were examined and PAR, IOTN and ICON recorded.
Results The study showed significant correlations between IOTN and ICON with respect to need and PAR and ICON with respect to outcome.
Conclusion It appears that ICON does reflect UK opinion and the current study provides some evidence that ICON may effectively replace PAR and IOTN as a means of determining need and outcome.
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Acknowledgements
The authors would like to thank Alison Downing and Lynn May, Consultant Orthodontists at Middlesbrough General Hospital for their permission to examine records of patients under their care, the dental nurses for their help with data collection and Mrs M. Revelle for her help with the manuscript
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Appendix – the index of complexity, outcome and need
Appendix – the index of complexity, outcome and need
Practical use of the index to assess treatment need To use the index to assess treatment need the pre-treatment study models are examined and occlusal traits are scored according to the protocol below. The five occlusal trait scores are then multiplied by their respective weightings and summed (Table 4). If the summary score is greater than 43, treatment is indicated.
Practical use of the index to assess treatment outcome acceptability To assess treatment outcome, apply the index scoring method to the post-treatment models only. If the summary score is less than 31 the outcome is acceptable.
Practical use of the index to assess treatment complexity To assess treatment complexity, a five point scale is used via the cut points for the 20 percentile intervals, using the ranges given in Table 5 from the pre-treatment models.
Practical use of the index to assess the degree of improvement To assess the degree of improvement multiply the post-treatment score by 4, and subtract the result from the pre-treatment score. Use the ranges in Table 6 to assign a grade.
When the index is used to assess treatment outcomes, it is assumed that an appropriate level of co-operation was obtained from the patient. The index may require confirmation of the presence of teeth using radiography. Except for the aesthetic assessment, occlusal traits are not scored to deciduous teeth unless they are to be retained in the permanent dentition to obviate the need for a prosthetic replacement, for example when the permanent tooth is absent.
The index contains five components all of which must be scored.
Dental aesthetics The dental aesthetic component of the IOTN6 is used. The dentition is compared with the illustrated scale and a global attractiveness match is obtained without attempting to closely match the malocclusion to a particular picture on the scale (Fig. 5). The scale works best in the permanent dentition.
The aesthetic component of IOTN used as the first component of ICON
The scale is graded from 1 for the most attractive to 10 for the least attractive dental arrangement. Once this score is obtained it is multiplied by the weighting of 7.
Crossbite A normal transverse relationship in the buccal segments is observed when the palatal cusps of the upper molar and premolar teeth occlude preferably into the occlusal fossa of the opposing tooth or at least between the lingual and buccal cusp tips of the opposing tooth. Crossbite is deemed to be present if a transverse reaction of cusp to cusp or worse exists in the buccal segment.
This includes buccal and lingual crossbites consisting of one or more teeth with or without mandibular displacement.
In the anterior segment a tooth in crossbite is defined as an upper incisor or canine in edge to edge or lingual occlusion.
Where a crossbite is present in the posterior or anterior segments or both, the raw score of 1 is given which is multiplied by the weighting of 5.
Where there is no crossbite the score for this trait is zero.
Anterior vertical relationship This trait includes both open bite (excluding developmental conditions) and deep bite. If both traits are present only the highest scoring raw score is counted. Positive overbite is measured at the deepest part of the overbite on incisor teeth. Scoring protocol is given in Table 4.
Open bite may be measured with an ordinary millimetre rule to the mid-incisal edge of the most deviant upper tooth. Multiply the raw score obtained by 4.
Retained deciduous teeth (ie without a permanent successor) and erupted supernumerary teeth should be scored as space unless they are to be retained to obviate the need for prosthesis. In transitional stages average canine and premolar widths can be used to estimate the potential crowding. Suggested averages are 7 mm for premolar and lower canine and 8mm for upper canine. The presence of erupted antimeric teeth allows more accurate estimation for this purpose. Spacing due to teeth lost to trauma and exodontia is also counted.
Post-treatment spaces created to allow prosthetic replacements should match the antimeric tooth width. Discrepancy between such spaces and the anitmeric tooth can be counted as excess spacing or crowding, whichever is appropriate. The use of the index to assess spacing in relation to retained deciduous teeth demands that the fate of the deciduous teeth is known before the index can be applied.
Once the raw score has been obtained it is multiplied by the weighting 5.
Upper arch crowding/spacing This variable attempts to quantify the tooth to tissue discrepancy present in the upper arch or the presence of impacted teeth in both arches.
The sum of the mesio-distal crown diameters is compared with the available arch circumference, mesial to the last standing tooth on either side. This may require the use of a millimetre rule for accuracy, but with practice can be estimated by eye with reasonable accuracy.
No estimation is made to account for the curve of Spee or the degree of incisor inclination. Once the crowding/spacing discrepancy has been worked out in millimetres it is reduced on to the ordinal scale using the categories shown in Table 7.
Note that an impacted tooth in either the upper or lower arch immediately scores the maximum for crowding. A tooth must be unerupted to be defined as impacted.
An unerupted tooth is defined as impacted under the following conditions:
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If it is ectopically placed or impacted against an adjacent tooth (excluding third molars but including supernumerary teeth).
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When less than 4mm of space is available between the contact points of the adjacent permanent teeth.
Buccal segment antero-posterior relationship The scoring zone includes the canine premolar and molar teeth. The antero-posterior cuspal relationship is scored according to the protocol given in Table 7 for each side in turn. The raw scores for both sides are added together and then multiplied by the weighting 3.
Deviation of the final score Once all of the raw scores have been obtained and multiplied by their respective weights, they are added together to yield a single weighted summary score for a particular cast.
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Fox, N., Daniels, C. & Gilgrass, T. A comparison of the Index of Complexity Outcome and Need (ICON) with the Peer Assessment Rating (PAR) and the Index of Orthodontic Treatment Need (IOTN). Br Dent J 193, 225–230 (2002). https://doi.org/10.1038/sj.bdj.4801530
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DOI: https://doi.org/10.1038/sj.bdj.4801530
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