Jonathan Schofield is the Principal of The Dental Implant Clinic in Bath and a Senior Lecturer in Implant Dentistry at the University of Bristol
I have been involved in implant dentistry for 24 years. For the last few years I have been looking closely at the digital workflow related to implant dentistry. As a clinician, I am gradually adopting more aspects of the digital workflow, but I only adopt when I am convinced that there is an improvement on what I can currently offer to my patients.
So, what is the digital work flow in implant dentistry? I think it can be broken down into Implant placement and construction of the tooth on implants.
Digital Work Flow in Implant Dentistry:
- 3-D Imaging using CBCT scans
- 3-D planning of the position of the implants to be in the correct position to support the final teeth in the patient’s mouth
- Digital design and manufacture of a ‘guide’ to help place the implants in the right position (guided surgery)
Construction of the tooth on implants
- Digital impressions (using a 3-D camera in the mouth to take a photograph of the teeth and implants). This avoids having to use dental impressions
- Digital design and manufacture of the implant tooth substructure
- Digital design and manufacture of the implant tooth
To date, I have been impressed with the developments of computer aided design and computer aided manufacture. As a practice, we routinely use milled metal frameworks to be screwed to our dental implants. The metal frameworks act as the strong sub-structure to support the ‘tooth part’ of our restorations. The parts of the restorations which are visible in the patient’s mouth can be made of a number of types porcelain, acrylic and composite. These materials come in various tooth colours and a range of shades of pink if we need to reconstruct the pink of missing gum. For multiple missing teeth, we have been using hand made techniques for constructing the tooth part of our restorations. For single teeth at the back of the mouth we have also used pressed ceramics and milled ceramics which then have their final colouring performed by hand.
The computer aided design and computer aided manufacture discussed above have eliminated many of the inaccuracies of making frameworks by more traditional methods such as casting the metal. Casting is a multi-stage process, and at each stage there is a potential inaccuracy. This is big improvement for our patients as the teeth will fit more accurately.
A cast metal dental substructure still surrounded by some of its plaster cast
The cast metal dental substructure is then sand blasted to remove the plaster
However, another source of inaccuracy is the impression putty that dentists take of the patient’s teeth and gums. The impression is then cast in plaster. Both the impression taking and the plaster casting suffer from distortion and shrinkage. Furthermore, a considerable number of patients find the taking of impressions to be very unpleasant.
A silicone putty is currently used to take an impression of teeth. As the silicone sets inaccuracies can occur
Many of my patients cite the taking of impressions as one of the things that they most fear about visiting me. Other patients have a very sensitive gag reflex and taking of the impression and waiting for it to set is an unpleasant experience for them.
‘For me, the most exciting part is to use a 3-D camera in the patient’s mouth…and say goodbye to impressions’
So for me (and my patients) the most exciting part of the digital work flow in implant dentistry is to to use a 3-D scanner in the patient’s mouth to capture a picture of their teeth and say goodbye to impressions and all the unpleasantness associated with them. I am now convinced that the 3-d scanners that we can use in the patient’s mouth have come of age. I have looked at those that are on the market and I have been most impressed with the 3-Shape scanner by Trios. And this is what we are now going to use on our patients.
The Three Shape scanner means we can now eliminate impressions