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42 Orthodontics KCE Reports 77
EVALUATION IN THE LITERATURE OF THE DIFFERENT INDICES
In the systematic review of the SBU (The Swedish Council on Technology Assessment
in Health Care) in 2005 2 no scientific evidence was found to conclude on the validity
(that is, if a tool measures what it is intended to measure) of morphological priority
indices (indices based on deviations in the bite and the dental arch from an established
norm) and an insufficient evidence was found for the conclusions concerning the validity
of aesthetic indices from a sociodental perspective.
Notwithstanding this, many studies have been published that focus on evaluation and
comparison of different treatment indices.
In some studies, opinions of orthodontic practitioners and lay people were compared
for specific indices (e.g. Hunt et al 59 , Johanson et al 57 ).
The results of evaluation studies on the Index of Complexity, Outcome, and Need
(ICON) supported the use of the ICON as index of orthodontic treatment need 60 . A
comparison between the ICON, on one side and the PAR and IOTN, on the other side,
revealed that ICON does reflect the UK opinion and this study provides some evidence
that ICON may effectively replace IOTN and PAR as means of determining need and
outcome 61 .
Another study that compared the same three indices found that ICON is the most
critical index 62 , but up to now it has not been used in many countries already (see
Chapter 3). Another study claimed that the IOTN, among others (HLD (Handicapping
Labio-Lingual Index) and HMAR (Handicapping Malocclusion Assessment Record))
provided valuable information for determining orthodontic treatment need. In a
comparison between PAR and Summers’ Occlusal Index (SOI) it was concluded that
PAR index was found to be as reliable as Summers’ Occlusal Index 63 .
Another study showed that the DAI was simple in use. However, this index showed
some limitations, such as an under-estimation of the treatment need in malocclusions
with displaced canines, a deep overbite, unsatisfactory aesthetics of anterior teeth due
to incisor rotations and an over-estimation of the treatment need in cases with an
increased overjet in otherwise well aligned arches 64 .
The DAI index has the unique aspect that it is linking people’s perceptions of aesthetics
with anatomic trait measurements 65 .
The same study found the DMH a somewhat complex and subjective index to score.
The DHC of the IOTN was found to be over-sensitive in cases with increased overjet
and contact point displacements greater than 2 mm. The AC of the IOTN underestimated
treatment need in cases with excessive overjet and buccally displaced canines,
and over-estimated treatment need in cases with spaced arches and deep overbite 64 .
Despite obvious shortcomings treatment need indices are commonly used in several
countries. In the United States public health planners in fifteen states have developed
several occlusal indexes, using arbitrary cut-off scores, as the basis for eligibility for
public funds for orthodontic treatment 66 . In Germany the KIG index is used for this
purpose. In the UK, NHS reimbursement is based on the IOTN, and Norway also uses
the IOTN.
It should be noted that HAS u , the French National Authority for Health, nor the
American Academy of Pediatric Dentistry in their recommendations v on orthodontic
treatment, give the advice to use a certain index.
u Indications de l’orthopedie dento-faciale et dento-maxillo-faciale chez l’enfant et l’adolescent. Juin 2002.
Agence Nationale d’Accréditation et d’Évaluation en Santé (ANAES; nowadays HAS)
v Clinical guideline on management of the developing dentition and occlusion in pediatric dentistry.
American Academy of Pediatric Dentistry - Professional Association. 2001 (revised 2005). 18 pages.
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