Does relative maxillary arch constriction worsen with growth in patients with Cleft lip and palate? A pilot study

Objective: To evaluate an automated software tool for the assessment of dental arch relationships using the modified Huddart and Bodenham index.
Design: Cohort of 43 models of subjects aged 9-21 with UCLP and the ten GOSLON reference models sets.
Method: The 53 sets of plaster models were scored using the MHB index and scanned (R700, 3Shape, Copenhagen, Denmark). The digital models were MHB scored visually (Orthoanalyzer, 3Shape, Copenhagen, Denmark) and landmarked for automatic scoring using a Rhino software plug-in (Rhinoceros, version 5, www.rhino3d.co.uk). Scoring/landmarking was undertaken by three observers and repeated after one month. Intra- and inter-observer reproducibility were tested using Cronbach’s Alpha and intraclass correlation coefficients (ICC) (threshold > 0.9). Bland-Altman plots demonstrated inter-observer agreement for each model format. Random and systematic error with digital landmark identification error were determined using the x, y and z co-ordinates for 28 models digitized twice one month apart using Cronbach’s alpha and a t-test, respectively.
Results: Intra-operator landmark identification was excellent (Cronbach’s alpha = 0.933) with no differences between sessions (P>0.05). Intra-observer reproducibility was excellent for all examiners (Cronbach’s alpha and ICC 0.986-0.988). Inter-observer reproducibility was highest for the software plug-in (0.991), followed by plaster (0.989) and Orthoanalyzer (0.979) and Bland-Altman plots confirmed no systematic bias and greater consistency of scores with the automated software.
Conclusion: The automated MHB software tool is valid, reproducible and the most objective method of assessing maxillary arch constriction for patients with UCLP.