August 1, 2006
by Bake Nicolucci, BSc., DDS
The latest craze in implant dentistry is ‘teeth in an hour’. This is possible through the use of the CT scan, and the available programs used view the scan from a dental perspective. These programs allow you to preview the implant placement before anesthesia is even administered. Implant number, angulation, length and width can all be pre-determined so that surgical templates can be produced to speed up the surgery, and increase the safety factor at the time of surgery. The posts, temporaries, and even final crowns can be pre-manufactured so that the entire system can be assembled immediately after implant placement. It is a wonderful advancement for implant dentistry, but when do you start the clock?
I’ve seen the movie clips of patients who undergo surgery to receive all of their implants and proceed to bite into an apple, and tell the audience how great it is to have teeth, but there are numerous criteria to consider before the dentist considers going this route — and the question then becomes, “when does the clock start ticking?”
If you were to do four anterior crowns, it would be hard to say that you could do all of these crowns ‘in an hour’. The preliminary impressions are completed at the first appointment with a bite registration, a face-bow and all of the protrusive and lateral excursion records. The teeth are then reduced and impressed and the new casts mounted with a face bow. The patient is then brought back two weeks later to cement the crowns a laboratory had processed. If we start the clock at the point we mix the cement, then I can say I did ‘four anterior crowns in less than an hour’. This is just something I want you to think about. The analogy is not exactly parallel, but there is lots of preparatory work to be done before anyone gets ‘teeth in an hour’- no matter what scenario you use.
The idea that Cat scan models can aid in the production of the surgical template used to place the implants, design the angulation of the abutments, and process the final teeth for the abutments is a wonderful advancement in implant dentistry. As a matter of fact, I believe that cat scans are becoming so important in advanced implant dentistry they are going to become the ‘standard of care’ in the near future. I’m not saying they are required for simple ‘single tooth replacement’, but for sinus elevations in particular, they give a wealth of information. It can indicate pathology, mucous retention cysts, septa, membrane thickness, as well as bone availability and bone density. Even for implant placement, a CT scan can measure to within 0.1mm the exact width of the slices of the ridge. This will aid in determining whether or not a block graft, or ridge splitting will be required before or during the surgery.
Bone density can also be calculated from a CT scan. The ‘Hounsfield unit’ is used as a radiological scale for bone density and can be calculated for any specific point on the scan. This bone density information can help to determine the number of implants that should be placed to produce a predictable long-term result.
The exact location of the important landmarks can also easily be identified from a CT scan. For implants in the posterior mandible, the mandibular canal can easily be identified and enhanced so that implant placement can be done with relative ease and safety. Also, the depth and position of the mandibular fossae can be evaluated so that implants will not perforate the lingual cortical bone and cause unnecessary complications with nerves and blood vessels. Implants in the posterior maxilla will require locating the sinus and determining whether or not there is adequate bone available for implant placement. Implants in the anterior mandible are facilitated by the scan since the angulation of the mandibular bone and the depth of the digastric fossae can be established prior to surgery. Implants in the premaxilla can also profit from a CT scan. The position and size of the incisive canal, the depth of bone under the piriform rim of the nose, and the angulation of the bone can all be identified and measured pre-surgically.
The advantages of the CT scan are enormous. The programs to read the scans may sound a little expensive, but when you compare the costs of repairing complications that could have been avoided using the scan (and/or the costs of litigation), this expense is not out of line.
Thus we get back to ‘teeth in an hour’. The future of implants looks very bright, thanks to new improved innovations. But, the concept of having ‘teeth in an hour’ should be explained in detail to our patients. For the novice implant dentist, I would like to suggest that you get some real ‘hands-on’ experience, and wait to see some long term results before trying to give your first patient ‘teeth in an hour’.
Dr. Nicolucci is president of the Canadian Society of Oral Implantology and is Oral Health’s editorial board member for Implantology.
Your email address will not be published. Required fields are marked *
Save my name, email, and website in this browser for the next time I comment.