ORTHODONTICS

The Joint Oireachtas Committee on Health and Children issued its report on the Orthodontic Service in Ireland on 26.02.2002. Click here for a summary of the recommendations.

More recently (January 2007), the Report of the Orthodontic Review Group was accepted by HSE Management.

The 1985 DOH&C Guidelines on Secondary Care Orthodontics are effectively redundant. They are available here for historical interest. Download as 24 KB WORD document here:
Orthodontic referral guidelines

Index of Treatment Need (IOTN)

Introduction

The Index of Treatment Need originated from the 1986 Schanschieff report into unnecessary dental treatment, which drew the profession's attention to the varied standard of orthodontic care in the general dental services. In 1987 the Occlusal Index Committee proposed the development of indices that would measure need for treatment and the quality of the outcome of treatment. This resulted in the development of the Index of Orthodontic Treatment Need (IOTN) and the Peer Assessment Rating (PAR). The IOTN is designed so that a malocclusion may be quickly assessed clinically or from clinical models, but it is most widely used clinically. The PAR index is a method of quantifying the severity of a malocclusion on study models. If this is done before and after treatment, then the change can be measured and thus the quality of the outcome of care measured. The two indices are used in different ways for different purposes.

Malocclusion describes a spectrum of deviation from the normal or ideal to very severe anomalies. Clinicians and potential patients and their families may have differing views of what should be treated and what should be accepted as a modest and harmless variation. There is also likely to be variation among groups of clinicians and also between primary care referring practitioners and specialist orthodontists. The IOTN is a useful tool for those interested in research into Dental Public Health and the epidemiology of malocclusion, but it is most widely used by specialists, who may wish to demonstrate to authorities that provide the resources for orthodontic care that they are targeting these resources at the individuals who will benefit most from treatment. Its use will reduce the inevitable subjective bias, which results from clinical opinion alone. Patients with a low IOTN are unlikely to show a great change as a result of even the highest standard of treatment, something which can be demonstrated readily by the PAR Index. For research and epidemiology use, the observers must be properly trained and calibrated, but in clinical use, especially by primary care practitioners, such a high standard is not required to use the IOTN as a useful clinical tool.

Because orthodontic treatment needs to be justified on either dental health or aesthetic needs, there are two components to this index:-

The Dental Health Component of the IOTN has five categories ranging from 1 (no need for treatment) to 5 (great need) which may be applied clinically or to patients' study casts. The most severe occlusal trait is identified for any particular patient and the patient is then categorised according to this most severe trait. Patients in Grade 5 would include patients with Cleft Lip and Palate, multiple missing teeth or a destructive malocclusion, which would include those with minor tooth displacements where there is little need for treatment.

The Dental Health Component uses a simple ruler and an acronym - MOCDO - to guide the observer to the single worst feature of the malocclusion. MOCDO represents Missing teeth; Overjets; Crossbites; Displacement of contact points; Overbites. There are 5 categories, from 1 representing no need for treatment to 5 representing a great need for treatment. Thus a patient who has an impacted upper incisor is immediately categorised as falling into the highest group - IOTN 5 - and no further assessment of the DH Component is required. Where there are no anomalies of tooth number or position, the ruler will be useful to measure the overjet (positive or negative), to see where this will place the patient. So an increased overjet in the range 6-9mm will be IOTN 4.

The Aesthetic Component of the IOTN consists of a ten-point scale illustrated by a series of photographs which were rated for attractiveness by a lay panel and selected as being equidistantly spaced through the range of grades (Evans and Shaw, 1987). A rating is allocated for overall dental attractiveness rather than specific similarities to the photographs. The final value reflects the treatment need on the grounds of aesthetic impairment and by implication the sociopsychological need for orthodontic treatment. Both parents and patients find this easy to apply and there is a high level of agreement between the scores obtained by dentists, parents and children.

There seems to be a general agreement that a DHC of less than 4 and an AC score of below 7 do not justify treatment by a hospital based consultancy except for teaching or research purposes.

The Dental Health Component

Grade1
No treatment required
  
 
1.
 Extremely minor malocculsions, including displacements less than 1 mm

Grade 2
Little
  
 
2.a
 Increased Overjet > 3.5 mm but <= 6 mm (with competent lips)
 
2.b
 Reverse overjet greater than 0 mm but <= 1mm
 
2.c
 Anterior or posterior crossbite with <= 1mm discrepancy between retruded contact position and intercuspal position
 
2.d
 Displacement of teeth > 1mm but <= 2mm
 
2.e
 Anterior or posterior open bite > 1mm but <= 2mm
 
2.f
 Increased overbite >= 3.5mm (wthout gingival contact)
 
2.g
 Prenormal or postnormal occlusions with no other anomalies. Includes up to half a unit discrepancy

Grade 3
Borderline need
  
 
3.a
 Increased overjet > 3.5 mm but <= 6 mm (incompetent lips)
 
3.b
 Reverse overjet greater than 1 mm but <= 3.5mm
 
3.c
 Anterior or posterior crossbites witt >1mm but <= 2mm discrepancy between the retruded contact position and intercuspal position
 
3.d
 Displacement of teeth >2mm but <=4mm
 
3.e
 Llateral or anterior open bite > 2mm but <= 4mm
 
3.f
 Increased and incomplete overbite without gingival or palatal trauma

Grade 4
Treatment required
  
 
4.a
 Increased overjet > 6mm but <= 9 mm
 
4.b
 Reverse overjet > 3.5 mm with no masticatory or speech difficulties
 
4.c
 Anterior or posterior crossbites with > 2 mm discrepancy between the retruded contact position and intercuspal position
 
4.d
 Severe displacements of teeth > 4 mm
 
4.e
 Extreme lateral or anterior open bites > 4 mm
 
4.f
 Increased and complete overbite with gingival or palatal trauma
 
4.h
 Less extensive hypodontia requiring pre-restorative orthodontics or orthodontic space closure ot obviate the need for a prosthesis
 
4.l
 Posterior lingual crossbite with no functional occlusal contact in one or more buccal segments
 
4.m
 Reverse overjet > 1 mm but < 3.5 mm with recorded masticatory and speech difficulties
 
4.t
 Partially erupted teeth, tipped and impacted against adjacent teeth
 
4.x
 Existing supenumerary teeth

Grade 5
Treatment required
  
 
5.a
 Increased overjet > 9 mm
 
5.h
 Extensive hypodontia with restorative implications (more than one tooth missing in any quadrant requiring pre-restorative orthodontics)
 
5.i
 Impeded eruption of teeth (apart from 3rd molars) due to crowding, displacement, the presence of supernumerary teeth, retained deciduous teeth, and any pathological cause
 
5.m
 Reverse overjet > 3.5 mm with reported masticatory and speech difficulties
 
5.p
 Defects of cleft lip and palate
 
5.s
 Submerged deciduous teeth


Aesthetic Component

  • Grade 1 = most aesthetic arrangement of the Dentition
  • Grade 10 = least aesthetic arrangement of the Dentition

  • Grade 1-4 = little or no treatment required
  • Grade 5-7 = moderate or borderline treatment required
  • Grade 8-10 =treatment required

The evaluaton of a plain Plaster model or Black and White Photographs has the advantage that the estimate is not influenced by the oral hygiene, the condition or colour of the gingiva.

Index of Complexity, Outcome and Need (ICON)

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 1). If the summary score is greater than 43, treatment is indicated.

Table 1. ICON index variables, weightings and cut-off values for treatment need and outcome decisions
Occlusal trait ICON index weighting
IOTN Aesthetic Component
7
Left + right buccal
3
Antero-posterior upper arch crowding
5
Overbite
4
Crossbite
5
Treatment need cut-off
43
Treatment outcome cut-off
31

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 th 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 percentileintervals, using the ranges given in Table 2 from the pre-treatment models.

Table 2. ICON index complexity cut-off values
Complexity grade Score range
Easy
less than 29
Mild
29 to 50
Moderate
51 to 63
Difficult
64 to 77
Very difficult
greater than 77

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 3 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.

Table 3. Pre-treatment - 4 (Post-treatment) ICON index score ranges, for ratings of treatment improvement
Improvement grade Score range
Greatly improved
> -1
Substantially improved
-25 to -1
Moderately improved
-53 to -26
Minimally improved
-85 to - 54
Not improved or worse
< -85

Dental aesthetics
The dental aesthetic component of the 10TN6 is used. The dentition is compared with the illustrated scale and a global attractive-ness 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 scale is graded from I 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 1
.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 (i.e. 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 antimeric 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 4.
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:
1. If it is ectopically placed or impacted against an adjacent tooth (excluding third molars but including supernumerary teeth).
2. 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 4 for each side in turn. The raw scores for both sides are added together and then multiplied by the weighting 3.

Derivation 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

Table 4. Protocol for occlusal trait scoring
 
Score
0
1
2
3
4
5
Aesthetic 1-10 as judged using SCAN            
Upper arch crowding Score only the highest trait either spacing or crowding < 2mm 2.1mm-5mm 5.1-9mm 9.1-13mm 13.1-17mm >17mm or impacted teeth
Upper spacing Up to 2mm 2.1mm-5mm 5.1-9mm >9mm    
Crossbite Transverse relationship of cusp to cusp or worse No crossbite Crossbite present        
Incisor open bite Score only the highest trait either open bite or overbite Complete bite < 1mm 1.1-2mm 2.1-4mm >4mm  
Incisor overbite Lower incisor coverage Up to 1/3 tooth 1/3-2/3 coverage 2/3 up to full covered Fully covered    
Buccal segment antero-posterior Left and right added together Cusp to embrasure relationship only. Class I, II or III Any cusp relation up to but not including cusp to cusp Cusp to cusp relationship      

 

Evans R and Shaw WC. Preliminary evaluation of an illustrated scale for rating dental attractiveness. European Journal of Orthodontics 1987; 9:34-318

Richmond S, Shaw WC, et al. The relationship between the index of orthodontic treatment need and consensus opinion of a panel of 74 dentists. BDJ 1995; 178(10): 370-374