Are any 3D printed materials biocompatible (safe for implantation in the human body)?
Perhaps more than biocompatible, which generally refers to a material that does not illicit a harmful inflammatory response inside the body, you should be looking at bioresorbable materials, which are materials that dissolve inside the body after a certain time period without needing mechanical removal. 

As an example, FDA approved poly (lactic acid) is available in pellet form from Corbion (formerly PURAC biomaterials) and can be extruded into 1.75mm filament for use with any desktop 3D printer (https://www.sciencedirect.com/science/article/pii/S2214860416301385). Similarly, researchers have used poly (caprolactone) to 3D print scaffolds with using a stratasys FDM machine (https://onlinelibrary.wiley.com/doi/pdf/10.1002/1097-4636(200105)55:2%3C203::AID-JBM1007%3E3.0.CO;2-7).