Evaluation of the accuracy of a simplified hybrid method versus the traditional digital method for measuring palatal...

This study aimed to compare a direct conventional 3D digital technique vis a vis a hybrid method in measuring palatal volume.

Thirty maxillary casts were obtained from the records of patients undergoing orthodontic treatment and pre-conceived boundaries of the palatal vault were marked. Sample was categorised into Group I (Volume estimation using CBCT scan) and Group II (Volume estimation using hybrid method). Estimation of the palatal volume in this study involved filling the volume of interest in the palate with gypsum (Type IV) stone material and carefully carving according to the boundaries and anatomy. This positive reproduction of the palatal space was safely retrieved and then scanned in the NewTom GiANO HR Cone Beam Imaging setup. The obtained scan was analysed in NNT Software Version 3.10 and the volume of the palate was calculated. Two experienced orthodontists carried out the measurements to evaluate the inter and intra-observer reliability. This was compared with the palatal volume calculated by the conventional digital method using CBCT in the NNT Software.

This study showed a consistent and narrow range of the confidence interval for palatal volume. Hence, the sample size was sufficient and had good precision. Considering a 95 % confidence interval, the intra-class correlation coefficient was robust (>0.9) for all measurements calculated by the hybrid method suggesting a high reliability. The mean difference in measurement of palatal volume (Group I vs, Group II) was 1.37 + 0.64 mm3 and the difference was statistically insignificant. Statistical t-test conducted between the two methods showed a p-value of 0.34, implying no statistically significant difference between the two methods.

The hybrid method for evaluating the palatal volume is simple, accurate and comparable to the conventional digital method. A major advantage of this simplified method is that the patient is not exposed to any radiation of CBCT. Also, need for a specific skillset for digitally measuring the palatal volume is not a must.