Lower denture model on 4 "pin style" abutmentsFor prosthodontic practices explaining All on 4 mechanics posterior angled implants and pin style abutments let patients visualize and feel how the full arch fixed restoration functions. Lower denture model on 4 "pin style" abutments. The posterior implants are at a 30 degree angle. This method is called the "all on 4". The denture is removable and is available in upper and lower model.