# Implementation of Fused Filament Fabrication in Dentistry
## 3 Novel Approaches of FFF in Dentistry  
### Thermoplastic Filament for Bite Registration  
Using FFF in combination with a temperature-sensitive material, a novel approach for bite registration seems to be beneficial for both the patient and the dentist. In the conventional workflow, a bite registration is performed using base plates made of light-curing acrylic and attached wax walls. The wax bite blocks are adjusted on the patient according to functional and esthetic aspects in order to convey the relation of the jaws to the dental technician. Today, based on an intraoral scan, the base plates can be digitally designed and additively manufactured using FFF in a simple and cost-effective manner. The use of a temperature-sensitive filament (Thibra3D Skulpt, Formfutura, Nijmegen, The Netherlands) allows adjustments to be made to the printed material instead of wax bite blocks. For this purpose, the printed material is heated in a hot water bath, with an alcohol burner or a hot air gun. The printed filament has a low working temperature of 70 \({}^{\circ}\)C, which is ideal for modeling. It can be processed unlimitedly after 3D printing and also enables the further application of the thermoplastic material. The filament is not yet classified as a medical device but ongoing cytotoxicity tests reveal promising results. The presented feasibility test (Figure 3) aimed to demonstrate the use of a temperature-sensitive filament in the dental workflow. Compared to the conventional adjustment of wax, this material is pleasant to model and holds great promise for clean and fast work on the patient.  
Figure 3: (**a**) STL model of the upper jaw with a flat contact surface, (**b**) STL model of the lower jaw with a flat contact surface, (**c**) bite plates manufactured by FFF (**d**) fitting of the bite plates.  
To further reduce treatment time on the patient, the jaw relation of existing prostheses can be implemented in the digital workflow. In the presented case (Figure 3), the intraoral implant scans (TRIOS 4, 3 Shape, Copenhagen, Denmark) of the upper and lower jaw were the basis for the design of the registration plates. By utilizing the existing screw-retained antagonistic prosthesis, a buccal scan was taken to obtain a preliminary bite registration. An automated tooth set-up ([PERSON], Gais, Italy) was integrated into the CAD of the base plates, which allowed the first visualization of a potential tooth set-up. In addition, a \"Plane Cut\" was inserted in the occlusal plane in the Meshmixer software (Autodesk, Mill Valley, CA, USA) so that the upper and lower jaw had a flat contact surface as known from the conventional procedure (Figure 3a,b). The final designed base plates were subsequently 3D printed with the Prusa i3 (Prusa, Prague, Czech Republic) at a printing temperature of 205 \({}^{\circ}\)C using the previously described temperature-sensitive filament (1.75 mm). Only minimal post-processing was needed to obtain the final bite plates.  
On the patient, the bite planes were inspected and slightly adjusted after heating in a water bath (Figure 3c,d). Finally, the bite plates were attached to each other by heating the occlusal surface with a hot instrument, after which the guides were removed from the mouth as a pair.