Digital technologies have changed the face and hands of dentistry, the increased accuracy and applications of optical scanners, cone beam tomography and CAD-CAM manufacturing technologies have impacted tremendously our field. The increasing use of these technologies in dentistry, allowed the reduction of manual handling of specimens throughout the various processing steps of the workflow.
Currently the applications of 3D printing of polymers in dentistry include: fabrication of anatomical replicas for surgical training or planning, fabrication of facial and dental temporary prostheses, orthodontic aligners, occlusal splints and night guards, surgical guides, casts and dies.
Although possessing multiple applications and potential future developments, 3D printing also has some limitations:
First, the accuracy of 3D printed structures can variate according to forms being reproduced, the method of printing, and the materials being used. SLA can fabricate structures with a layer thickness of 25μm or more. Inkjet printing can achieve a layer thickness of 12μm, while FDM has been shown to have accuracy of around 127μm.
Second, the staircase effect, given the layer-by-layer characteristics of additive manufacturing, that can be minimized by reducing the layer thickness. Third, the increment in the resolution will increase the building time. Fourth, the reproducibility of many additive machines still can’t print to the accuracy or reproducibility required for certain dental applications. Fifth, the addition of structures of support, adds an extra step during the fabrication and post-printing phase phases.
In dentistry, the 3D printing of dies, surgical guides, orthodontic aligners, temporary restorations and dental models is increasing exponentially, and there is a lack of information about the surface characteristics, surface changes, and volumetric stability of 3D printed structures, that are obtained when the printing parameters are modified to obtain more speed in the printing processes.
The 3D resin printed objects in the dental field must be stable, precise and accurate (dental dies, surgical guides). They will interact also, with the oral tissues, cells and bacteria in the case of surgical guides, orthodontic appliances and provisory restorations. These interactions depend on the surface characteristics, material properties and chemistry and little is known from the published literature about these facts.