Republished with special permission of The Technologist, Dental Technlogist’s Association.
Undoubtedly digital dentistry is the current topic. Over the last five years, the entire digital workflow has progressed in leaps and bounds. There are so many different digital applications that it is sometimes difficult to keep up with all the advances. Many dentists and technicians are excited about the advantages of new technologies, but there are an equal number who doubt that the improved clinical workflow justifies the expense.
I have worked closely with Borough Crown and Bridge – Andy Morton and Ian Murch – for the last 10 years and at times we have had steep learning curves and dealt with many
issues as a team but, importantly, we share our experiences and feedback.
I have often heard the argument that there is no need to try and fix something that is not broken. It is so true that impressions have their place and there are certainly limitations to the digital workflow that anyone using the technology should be aware of. For me, however, the benefits of digital far outweigh the disadvantages. In fact, the disadvantages are the same as with conventional techniques.
Chairside CAD/CAM single-visit restorations have been possible for over 20 years, but the accuracy of what was produced was always questionable. However, the ability to connect the intraoral scanner to a laboratory-based milling unit to enable a ceramic restoration to be produced by a technician was clearly an advantage – even with a model-free workflow, for those brave enough. Of course the scope was limited to smaller, single-unit restorations but the technology demonstrated that this new workflow was
desired by clinicians, technicians and patients alike.
This was the first step in the digital dentistry revolution and it was dental technicians who were the early adopters. The movement away from the lost-wax technique to customised milling – CAD/CAM technologies – was driven purely by dental technicians wishing to become more efficient in terms of time management, production volume,accuracy and cost efficiency. However, it did mean there was a capital investment required in the new technologies – and it is important to think of this as an investment not an expense.
What is digital implant dentistry?
Many implant clinicians have probably been using CAD/CAM workflows without even knowing, as many laboratories implemented the technologies without their clinicians realising it, substituting the lost-wax technique and the expense of gold for fully customised cobalt-chromium milled abutments (Fig.1).
One of my most important goals in seeking to be a successful implantologist is to provide a dental implant solution that is durable. We have seen a massive rise in the incidence of peri-implantitis and have found that a large proportion of these cases can be attributed to cement inclusion from poorly designed cement retained restorations (Fig. 2).
Even well designed, fully customised abutments and crowns can have cement inclusion if the restoration is not carefully fitted (Fig. 3).
This has led to a massive rise in retrievability of implant restorations, with screw-retained crowns and bridges now being the goal. However, making screw retained prostheses places even greater emphasis on treatment planning and correct implant angulation.
With dental laboratories as early adopters, we have been milling titanium or zirconia
customised abutments for over ten years. What has changed recently in the digital
revolution is the rise of the intraoral scanner. We now have a workflow in
which we can take a preoperative intraoral scan and combine this with a CT scanusing coDiagnostix (Dental Wings) in order to plan an implant placement accurately and safely. We can also create a surgical guide to aid in accurate implant placement,
have a temporary crown prefabricated for the planned implant position and then take a final scan of the precise implant position for the final prosthesis.
Accuracy of intraoral scanners
Figures 4–14 show the workflow for preoperative scanning, which includes the
implant design, guide fabrication and surgical placement of two fixtures.
While we do not think of intraoral scanners as being any more accurate than
good quality conventional impressions, there are many benefits of scanning, such
as impressions not being lost in the post and an almost zero re-impression rate
creating predictability and reliability.
I have three different scanners in the practice: the iTero (Align Technology), the CEREC Omnicam (DENTSPLY Sirona) and the Straumann CARES Intraoral Scanner (Dental Wings; Fig. 15). The CEREC Omnicam is fantastic for simple chairside CAD/CAM restorations, such as IPS Emax all-ceramic restorations on Variobase abutments. For truly aesthetic results we, of course, work with our dental laboratory.
For single (aesthetic) and multiple-unit cases, we use the iTero and Straumann scanners. The latter we have only had at our disposal since February. The technology is great, as is the now openness of the system, which provides the advantage of being able to export STL
files into planning software. We even use the scanners for orthodontic cases now instead of wet impressions. I invested in the iTero scanner five years ago and have used it for everything, from simple conventional crowns and bridges, to scanning for full-mouth rehabilitations.
When fabricating definitive implant frameworks for bridges, we use Createch Medical for screw-retained CAD/CAM milled titanium and cobalt-chromium frameworks. Even though intraoral scanning appears extremely reproducible and accurate, blind belief in the accuracy
of technology can lead to trouble because we have found there can be significant inaccuracies between the scan and actual implant position – to ensure a truly passive framework we resort to ‘analogue’ technologies, such as verification jigs.
Clinical case to demonstrate our digital workflow:
Linking my workflow to my dental laboratory
There are many ways digitisation has improved dentist-laboratory relationships
and communication: from the basic use of the iPhone, to digital SLR cameras for picture transfer, to the use of intraoral scanners to substitute wet impressions and allow direct data transfer.
For the last few years, model production and accuracy have improved greatly – milled iTero models are almost indestructible and the pindexing system is very rigid, allowing excellent contact point accuracy on restorations.
Recently, with advances in 3D printing, rigid models can be printed which don’t wear or chip like conventional stone models. The pindexing is very precise but articulation and accuracy are still to be questioned.
We can now use printing technology to create surgical guides for precise implant placement. However, we must remember there are inaccuracies with every technology we
implement but if we can keep this in mind we can ensure the patients’ best interests are kept at the forefront. We are exposed to so many new techniques and technologies, we must ensure that it is not at the expense of the end user – our patients. To conclude, digital dentistry is the future and so why not take advantage of it and
help improve your clinicians’ and ultimately the patients’ clinical outcomes.
Dr Ross Cutts BDS (Lond) Dip Imp Dent RCS (Eng)
Practice Principal, Cirencester Dental Practice
Ross graduated from Guy’s Hospital, London in 2000. He is a dentist with Special Interests in Implant Dentistry and Advanced Restorative Procedures. He has placed over 2,000 implants in the last 10 years.
He is a Fellow of the International Team for Implantology (ITI) – and is a Study Club Director and clinical mentor for this Worldwide Organisation. He regularly holds implant courses and lectures nationwide on a variety of topics at different levels, however he has a particular interest in Aesthetic Implant Dentistry, Digital Dentistry and complex bone grafting procedures.