26 September 2022

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3D-printed retainers VS thermoform retainers: which have the best fit?

Massimo Gagliani

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Advances in digital dentistry have paved the way for the use of computer-aided design (CAD) technology in the modern orthodontic practice. Today, a 3-dimensional (3D) digital model, produced with an intraoral scanner, can be easily manipulated to perform the necessary measurements to facilitate diagnosis and treatment planning. In addition, digital technology eliminates the need for storage space and makes the retrieval and transfer of the models easier.  
In the study of Colea et al., published on the American Journal of Orthodontics and Dentofacial Orthopedics, 24 models were taken, both with traditional anagogic techniques (alginate impressions) and with intra-oral scanners (two groups). The first group the retainer was thermo formed while a digital printer was employed for the second group and third group using an STL file.      

Average differences of the conventional vacuum-formed retainers ranged from 0.10 to 0.20 mm. The commercially available and 3D-printed retainers had ranges of 0.10 to 0.30 mm and 0.10 to 0.40 mm, respectively.   

The traditional vacuum-formed retainers had the least amount of deviation from the original model. 3D-printed retainers are good alternatives to the traditional vacuum-formed retainers. Retainers may be successfully 3D printed with the use of stereolithography technology.