Digital workflow to produce CAD/CAM fixed prosthesis (Lava Plus) on dental implants (Straumann) with the use of CBCT based (flapless) Guided surgery (coDiagnostix) and Intra-oral Scanning (True Definition Scanner - 3M)

In modern oral implantology digital technologies are applied incriesingly.
Since the introduction of CAD/CAM, dentistry has changed dramatically. Whereas
it was initially primarily used in dental laboratories this is changing rapidly
and shifting to the dental practice, especially since several manufacturers are
offering devices for digital intra-oral impressions. One of the major
advantages of these developments is that once the digital image of a tooth or
implant is saved, the chances of mistakes due to technical errors in the
production process are minimal. Shrinkage, expansion, fracture, transportation
and storage of dental casts are eliminated. The success of this digital
workflow is thus entirely dependent on the accuracy of these scans. With dental
implants this is even more critical than with natural teeth because they lack
the resilience of the periodontal ligament.

Digital planning and guided surgery based on CBCT is another recent
development. This digital planning makes implantology more predictable and
surgery time shorter9. Additionally, extensive surgical interventions can be
avoided because of flapless approaches. Combining all these new techniques, it
should be possible to completely digitize the implantology workflow from
planning to production of the supra-structures.

In addition the intra-oral scans are used to evaluate volumetric changes in the
implanted area. For this purpose a partial intra-oral scan are taken from the
implanted site in each session. These files can be superimposed digitally and
volumetric changes will be observable very accurately. With the information
obtained with this method, it might be feasible to make guidelines of expected
volume loss in certain situations. With this information clinicians can
anticipate on signals that indicate future problems. This method is rather new
and there are no studies so far with volumetric data compared in each session.

The main purpose of the studies suggested in this proposal is to scientifically
test the digital workflow in implant dentistry. The following primary and
secundary goals are pursued:
Primairy:
1. Assessment of the clinical use of intra-oral scanning of dental implants and
comparing it with conventional impression methods. Comparing these methods on
*m-level is performed in another in-vitro experiment.
Secundary:
2. Testing the accuracy of computer guided implant placement with
tooth-supported drill guides produced with rapid prototyping.
3. Assessment of dimensional changes around implants evaluated during the
entire treatment phase.
Producing prosthetics on implants in fully digital (CAD/CAM) workflow.
Preferably without the use of a model of any sort.
4. Implant survival, surgical- and prosthetic complications are recorded up to
one year after restoring the implants. The clinical use of CAD/CAM restorations
on dental implants is thus quantified.

In general this study is a Double-blind randomized clinical trial. This double
blind qualification concerns the random selection of the produced
supra-structure. However remarks have to be made, since the randomization is
done after the applying both methods to the same patient. Furthermore the
methods itself are not interventions but (diagnostic) registrations on which an
intervention (placing the supra-structures) is based. The interventions itself
are more or less equal; both groups receive the same kind of supra-structures
and are subjected to the same restoration fit assessment.

The actual fit-checking is the primary outcome of this study. This assessment
is performed with a questionnaire on the fit which is filled in by the dentist
who performs all supra-structure placements. In addition a second dentist will
independently perform the fit check. If any disagreement is present a third
reviewer (the head of the department) will make the final decision on the
quality of the fit.

In this study titanium implants are inserted in the jaw bone. This is done with
a widely used and well documented implant type. This is thus not considered an
experimental intervention. De supra-structures, which will be placed on these
implants four months after insertion, are all made of zirconia-oxide; a widely
used and well docuemented restorative material in dentistry.

This application focuses primarily on applying an extra (non invasive)
measurement tool: the intra-oral scanner. De images gathered with this scanner
are used in half the patients to design the above mentioned zirconia-oxide
supra-structures. The fit of these supra-suprastructures is thoroughly tested
before they are finally attached. This is a regular procedure when placing
supra-structures. The chance of problems is thus not larger than with any other
conventionally produded suprra-structures. In addition to that, a
supra-structure is a reversible construction (it is not introduced into the
body). When problems or complaints do occur such a structure can relatively
easily be removed.

In our opinion this is not a study on an intervention per se, but a on a
(diagnostic) measurement tool used to do an intervention.

The additional risks for patients participating in this research are very
little. The implants and restorative materials used in this study are a well
known and thoroughly researched instruments. Although half the supra-structures
are designed based on a relatively new method (intra-oral scanning of dental
implants), a proper fit is guaranteed by a thorough clinical control before the
restoration will be installed definitively. If by any chance a restoration is
insufficient or fails a new restoration will be made based on a conventional
impression. This will obviously be free of charge for the patient. The most
significant effort for the patients are the extra intra-oral scans made at each
session (no radiation involved). These scans are in addition to the three
regular plaster models (conventional impressions) taken during such a treatment
protocol. The total extra time needed for these scans during the 15 months
period is estimated as 78 minutes. The patients do not need to bring extra
visits to our clinic. However it is expected that patient follow a, more or
less, strict time schedule. This time schedule (or planning) will be made in
conjunction with the patient and is important to make every treated patient
comparable.