Rating dental arch relationships and palatal morphology with the EUROCRAN index on three different formats of dental casts in children with unilateral cleft lip and palate

Background: The EUROCRAN index has been used in inter-center studies to assess dental arch relationship (DAR) and palatal morphology (PM) in children with unilateral cleft lip and palate (UCLP). For this type of inter-center research, a scoring method that could be performed over the internet would be the most effective. Therefore, the aim of this study was to investigate the reliability of application of the EUROCRAN index on 3D digital models or photographs of plaster models instead of using plaster models.

Methods: The EUROCRAN reference models were presented in three formats: plaster models, 2D photographs of plaster models, and 3D digital models. Plaster models of children with UCLP (n = 45) were rated. Of each case, all three formats were rated by six calibrated observers in random order. The strength of agreement of the ratings was assessed with kappa statistics. Concordance among observers was evaluated with the intra-class correlation coefficient (ICC).

Results: The ICC showed a good inter-observer agreement for the DAR and poor inter-observer agreement for the PM. Intra-observer agreement for the DAR was moderate to very good, yet for the PM poor to moderate. Comparison between the three formats per observer for the DAR was good or very good and for the PM moderate to poor.

Conclusions: The overall results show that the EUROCRAN index is an acceptable and reliable scoring method for the DAR on plaster models, 2D photographs of plaster models, and 3D digital models. However, due to the small range of deviations in palatal morphology between the cases in our study, the PM component of the index was difficult to assess.

Clinical relevance: In clinical audits and inter-center studies, plaster models can be substituted by 2D photographs of plaster casts or 3D digital models when grading treatment outcome with the EUROCRAN index.