The PAR Index has been developed to provide a single summary score for all the occlusal anomalies which may be found in a malocclusion. The score provides an estimate of how far a case deviates from normal alignment and occlusion. The difference in scores between the pre- and post-treatment cases reflects the degree of improvement and, therefore, the success of treatment. Excellent reliability was exhibited within and between examiners (Intraclass Correlation Coefficient, R> 0.91). The components of the PAR Index have been weighted to reflect current British orthodontic opinion and is flexible in that the weightings could be changed to reflect future standards and standards currently being achieved in other countries. The PAR Index offers uniformity and standardization in assessing the outcome of orthodontic treatment.

This paper is based on the winning submission for the 1998 Chapman prize awarded by the British Orthodontic Society for an essay on a subject promoting the interests of orthodontics. The aim of the investigation is to develop a single index for assessing treatment inputs and outcomes. An international panel of 97 orthodontists gave subjective judgements on the need for treatment, treatment complexity, treatment improvement, and acceptability on a diverse sample of 240 initial and 98 treated study models. The occlusal traits in the study models were scored according to a defined numerical protocol. Five highly predictive occlusal traits were identified (IOTN Aesthetic Component, crossbite, upper arch crowding/ spacing, buccal segment antero-posterior relationships, and anterior vertical relationship) and then used to ‘predict’ the panellist's decisions using regression analysis. Cut-off values were determined for the dichotomous judgements by plotting specificity sensitivity and overall accuracy. Twenty pe...

In orthodontics it is important to objectively assess whether a worthwhile improvement has been achieved in terms of overall alignment and occlusion for an individual patient or the greater proportion of a practitioner's caseload. An objective measure is described that has been validated against the subjective opinions of 74 dentists. Using the weighted PAR Index it was revealed that at least a 30 per cent reduction in PAR score is required for a case to be considered as ‘improved’ and a change of 22 PAR points to bring about ‘great improvement’. For a practitioner to demonstrate high standards the proportion of an individual's case load falling in the ‘worse or no different’ category should be negligible and the mean reduction should be as high as possible (e.g. greater than 70 per cent). If the mean percentage reduction in PAR score is high and the proportion of cases that have been ‘greatly improved’ is also high, this indicates that the practitioner is treating a great proportion of cases with a clear need for treatment to a high standard.

Craniofacial morphology is highly heritable, but little is known about which genetic variants influence normal facial variation in the general population. We aimed to identify genetic variants associated with normal facial variation in a population-based cohort of 15-year-olds from the Avon Longitudinal Study of Parents and Children. 3D high-resolution images were obtained with two laser scanners, these were merged and aligned, and 22 landmarks were identified and their x, y, and z coordinates used to generate 54 3D distances reflecting facial features. 14 principal components (PCs) were also generated from the landmark locations. We carried out genome-wide association analyses of these distances and PCs in 2,185 adolescents and attempted to replicate any significant associations in a further 1,622 participants. In the discovery analysis no associations were observed with the PCs, but we identified four associations with the distances, and one of these, the association between rs7559271 in PAX3 and the nasion to midendocanthion distance (n-men), was replicated (p = 4 × 10(-7)). In a combined analysis, each G allele of rs7559271 was associated with an increase in n-men distance of 0.39 mm (p = 4 × 10(-16)), explaining 1.3% of the variance. Independent associations were observed in both the z (nasion prominence) and y (nasion height) dimensions (p = 9 × 10(-9) and p = 9 × 10(-10), respectively), suggesting that the locus primarily influences growth in the yz plane. Rare variants in PAX3 are known to cause Waardenburg syndrome, which involves deafness, pigmentary abnormalities, and facial characteristics including a broad nasal bridge. Our findings show that common variants within this gene also influence normal craniofacial development.