# Implementation of Fused Filament Fabrication in Dentistry
## 3 Novel Approaches of FFF in Dentistry
### Surgical Guides  
The manufacturing of surgical guides with FFF can offer a simple and cost-effective workflow. Inexpensive, biodegradable, and steam-sterilizable filaments [30] are an interesting choice of materials. In a former evaluation of the manufacturing procedure of surgical guides, difficulties regarding precision and the fitting of FFF printed surgical guides on a cast model were observed [31]. In contrast, other studies showed no difference when compared with surgical guides produced by means of DLP [32]. Besides accuracy, other factors resulted in a deviation between the planned and realized implant positions of >1 mm [33; 34].  
A workflow has been established in which surgical guides are planned digitally and manufactured using FFF. Two different design softwares were used (CoDiagnostic, Dental Wings GmbH, Chemnitz, Germany; ImplantStudio, 3 Shape, Copenhagen, Denmark). In both cases, the exported STL file was transferred to the slicer software (PrusaSlicer, Prusa, Prague, Czech Republic) and printed without further modification (Figure 6a). A Prusa mini+ printer (Prusa, Prague, Czech Republic) with a biodegradable filament (Greentec Pro, Extrudr FD3D GmbH, Lauterach, Austria) was used for additive manufacturing. Although medical approval for this filament has yet to be obtained, pending cytotoxicity tests show promising initial results. The detailed view of the guiding structure of the coDiagnostic surgical guide (Figure 6b) reveals a smooth and precise surface, nevertheless, the individual layers of the FFF manufacturing process are visible.  
Figure 5: Dual material customized impression tray. The rigid body was manufactured with a polyethylene terephthalate glycol (PETG) filament (Trayfill), the rim was printed with a thermoplastic filament.  
The accuracy of surgical guides manufactured with FFF is a discussed topic since FFF is considered less precise than SLA /DLP. The in vitro accuracy of placed implants in relation to their virtual position with guides printed with FFF has already been investigated. Implants inserted using FFF printed guides showed equivalent deviations to those inserted using SLA guides and were within clinical tolerances of <1 mm [30]. It was shown that printed drill sleeves integrated into the surgical guide do not cause more deviation in the implant position, compared to traditional metal sleeves. This can be a major advantage in clinical applications, especially considering the potentially good biocompatibility of the biodegradable filaments.  
Great potential lies in the simplicity of handling and accessibility of the manufacturing process. The easy operability of the CAM software allows even first-time users to achieve useable objects. The surgical guides and the support structure are removable without tools. Without further post-processing, the guides can be steam-sterilized and directly used. Furthermore, this production route offers cost-effective manufacturing of surgical guides using FFF with printers available at competitive prices, software available free of charge, and a material cost of 50 cents per surgical guide. If a sleeveless design is adopted, further cost savings can be achieved. Further research on the design and optimization of surgical guides, as well as studies on the clinical application, are required. The influence of metal debris of the sleeves compromising the implant bed in conventional surgical guides compared to filament residues in sleeveless applications needs to be investigated.