Evaluation of the reliability and reproducibility of the digital models obtained from intraoral scanning and model scanning methods

The aim of this study is to evaluate the reliability and reproducibility of the measurements made on the digital models obtained from scanning the plaster models with the model scanner and using the intraoral scanner in different crowding groups such as mild, moderate and severe, by taking the measurements made on the plaster models as the gold standard. For this purpose, plaster and digital models obtained from two digital methods were created of 183 patients treated in our clinic. Patients were selected to have 3 groups of 61 patients in each group, with a mild (0-4 mm), moderate (5-9 mm), and a severe (10 mm and over) degree of crowded according to the amount of lower and upper arch length discrepancy. On the digital models and plaster models, the arch length discrepancy, anterior and overall Bolton ratio, the inter arch transversal distances between the canine teeth, 1st and 2nd premolar teeth, 1 st molar teeth were measured and the measurement times were recorded. The measurements of 30 randomly selected patients from each group were repeated at 2 week intervals. The reliability and reproducibility of the measurements made with both digital methods were evaluated by taking the measurements made on the plaster models as the gold standard and the methods were compared in terms of duration. As a result of repeated measurements, it has been observed that in all three groups, the methods were consistent and reproducible. When the results were evaluated in terms of linear measurements, statistically significant differences were observed between the two digital methods. Compared with the intraoral scanning method, the results obtained with the conventional method are more similar to obtained with the model scanning method. Measurements made by intraoral scanning method were found higher. However, this differences are at a level that can be ignored clinically. There was no significant difference in the arch length discrepancy, in anterior and overall Bolton ratio, at different crowding groups when compared with conventional measurements. When evaluated in terms of measurement durations, there was a statistically significant difference between the model scanning and the intraoral scanning method, and the duration of the procedure was measured longer by the intraoral scanning method. Reliable and reproducible measurements made with digital methods are promising in the future that digital models can be an alternative to plaster models. Also, digital models offer many advantages, such as the absence of risk of wear and breaking, the ability to store and back up easily, and the easy transfer of records between physicians for consultation. Key Words: Plaster model, digital model, model scanner, intraoral scanner, reliability, repeatability.