Using Little's Irregularity Index in orthodontics: Outdated and inaccurate?

Objectives

Little's Irregularity Index (LII) was devised to objectively score mandibular incisor alignment for epidemiological studies but has been extended to assess the relative performance of orthodontic brackets, retainer or treatment modalities. Our aim was to examine the repeatability and precision of LII measurements of four independent examiners on the maxillary arch of orthodontic patients. The hypothesis was that the reproducibility of individual contact point displacement measurements, used to calculate the LII score, are inappropriate.

Methods

The displacement of the anterior contact points, of the six upper labial segment teeth of the maxillary arch on each of ten casts, were randomly assessed by four examiners at three time-points using LII.

Results

Significant correlations were evident between the six examiner-pairs (r > 0.413; p < 0.001) for contact point displacements of >0.5 mm. The coefficients of variation showed that 516 of the 600 individual contact point displacement measurements differed by >20% of the mean. Analyses of variance revealed significant differences (p < 0.047) between examiners for 46% of the contact point displacement measurements.

Conclusion

The reproducibility of individual contact point displacement measurements, used to calculate the LII score, is poor such that using LII to assess the performance of orthodontic brackets, retainers or treatment modalities must emphatically be discouraged.

Clinical significance

The use of LII by the orthodontic community to predictably determine the outcome of orthodontic treatment modalities in clinical practice cannot be advocated due to the limited accuracy and precision of the technique.     

An EAACI position paper on the investigation of perioperative immediate hypersensitivity reactions

Perioperative immediate hypersensitivity reactions are rare. Subsequent allergy investigation is complicated by multiple simultaneous drug exposures, the use of drugs with potent effects and the many differential diagnoses to hypersensitivity in the perioperative setting. The approach to the investigation of these complex reactions is not standardized, and it is becoming increasingly apparent that collaboration between experts in the field of allergy/immunology/dermatology and anaesthesiology is needed to provide the best possible care for these patients. The EAACI task force behind this position paper has therefore combined the expertise of allergists, immunologists and anaesthesiologists. The aims of this position paper were to provide recommendations for the investigation of immediate‐type perioperative hypersensitivity reactions and to provide practical information that can assist clinicians in planning and carrying out investigations.