The digital workflow in implant dentistry
Authors:   , Derksen Wiebe Derk Cornelis 
Published: September 2023

Inserting dental implants to replace missing teeth is a well-established treatment concept. New digital developments are being introduced rapidly and are supposed to improve this already successful treatment modality. These digital techniques should improve predictability, reduce complications and make the treatments more efficient or cost-effective. The aim of this thesis was to evaluate some of these - already commercially available - new digital developments in implantology. The techniques studied in this thesis involve three major steps in this digital workflow.

1.	Implant placement using 'static computer guided surgery'. Meaning that the implants are inserted utilizing a drill guide – based on a three-dimensional pre-operative planning – to force the drills and implants in the correct direction. This planning requires the merging two three-dimensional scan files: an x-ray made with a cone beam CT scanner (CBCT) and a surface scan of the remaining teeth and gums made with an intraoral optical scanner (IOS). The merging of these scan files is called superimposing and facilitates the visualization of all important (anatomical) structures, allowing a pre-operative prosthetic- and surgical plan. When the plan is finished a 3D Printer creates a drill guide and the implants are placed accordingly. The prospective clinical trial of this thesis focused on tooth-supported drill guides in partially edentulous patients to replace one, two or three posterior teeth per treated side.

2.	When these implants are osseointegrated several months later, these same IOS can be used to register the exact location of these implants. This registration is necessary to create a well-fitting restoration to be fixed on these implants. This IOS is considered a 'digital impression' and can eventually replace conventional impressing techniques using compound-filled impression trays and plaster casts. The impressions studied in the prospective clinical trial of this thesis are used for implant-supported single crowns and fixed dental prosthesis supported by two implants (i.e. splinted crowns and three-unit bridges).

3.	The subsequent fixed restorations on these implants can be made using a digital process called CAD/CAM (computed aided design / computer aided manufacturing). Nowadays these restorations can be produced in full-contour made of one ceramic material (monolithic). This thesis focused on the use of monolithic zirconia restorations on implants and its performance over time.

The main conclusions which can be drawn from the included studies are that:
1.	Guided surgery techniques do not lead to perfect implant placement but it facilitates getting as close to your prosthetic treatment goal as possible
2.	Intraoral optical scanning appears to be more accurate for single implant crowns than conventional impression techniques and seems to be a predictable option for larger (two-implant) fixed dental prosthesis.
3.	Monolithic zirconia shows high survival-rates on implants. Since fractures and/or chipping can be perceived as a serious complication, which can often not be resolved or repaired completely, it can be concluded that monolithic zirconia restorations seem to outperform metal-ceramic (and especially zirconia-ceramic) restorations on implants.