Three-Dimensional Analysis of Dental Models Produced from Intraoral Scanning versus the Conventional Alginate Impression Method

Impression-making plays an important role in dentistry, where records of the oral cavity are needed to provide an optimum treatment plan for the patient. In this study, we utilised both the conventional impression method and the intraoral scanner (IOS) to make a comparison on the accuracy of the resulting oral cavity imprint using three-dimensional (3D) superimposition. In this study, a total of 18 participants were involved. Alginate impressions were made in a stock maxillary tray and poured with type III dental stone. The models were then scanned using IOS to generate virtual dental models where digital analysis can be made. For the IOS method, the scanning was done directly on the patient’s oral cavity by the same operator. Meshmixer software was utilised to convert the virtual models into a Standard Tessellation Language file, and then CloudCompare software program was selected to evaluate the volume, surface area, Dice similarity coefficient (DSC) and Hausdorff distance (HD) of the dental models produced from both methods. Statistical analyses were carried out using an independent t-test. It was revealed that the p-value of area and volume for both methods is > 0.05, which shows no significant differences. Besides, the mean and standard deviation for the HD were 0.02 and 0.01, respectively, which shows minimal differences between the two datasets. The mean DSC was also 0.9, which shows close to 100% overlap. These findings significantly indicate that conventional impression and IOS have comparable accuracy and are both reliable for impression-making.