The following individual presented to my practice my an edentulous maxilla and partially edentulous mandible.  An interim maxillary complete denture was fabricated, which served as the radiographic and surgical guide: once it was duplicated.  Implants were placed in sites #6,8,10,30.  Patient declined to undergo grafting procedures so implants in the pre-maxilla region were the best option available.  The mandible was restored using two FDP's from #19-21 and #22-27 with a single unit implant is site #30.  The vision for the final restoration is  a bar retained over denture.  
This techniques is a quick aid when setting denture teeth for the final restoration.  Assuming you like the position of the teeth in the trial denture, make a silicone matrix of that position indexed to the mandibular cast and voila!  You have created a great opportunity to visualize the concept of restorative space relative to the new implant master cast with the jig holding the teeth! 
https://youtu.be/GC26vx-_V-U
Ahuja.S, Cagna. D "Classification and Management of Restorative Space in Edentulous Implant Overdenture Patients" JPD May 2011 Vol 105 Issue 5