In my years of working with dental implants the surgical process has changed due to technology as radically as gasoline engines have morphed into Tesla’s.
When I first started in practice, panoramic machines were common but cone beam scans were not widely available. Using a 2-D panoramic x ray with 3mm radiopaque calibration markers and a wet periapical film provided all the available information, in addition to my knowledge of anatomical structures, and what areas to include or avoid.
3 mm radiopaque markers were placed in the mouth with a guide or appliance during the panoramic capture and then measured on the resulting film to decide the relative distortion of the panoramic at the area of the planned implant.
The panoramic x ray was then traced onto a paper using a light box. A clear plastic template with various distortion adjustments of 10% to 25% was placed over the light box tracing. The template included cutouts of the implants in various sizes to correlate with the predicted distortion of the panoramic film. The implant cut out of the correct size was traced over the paper in the correct surgical orientation.
Each parameter of implant location including root proximity, bone width and implant length was noted on a planning sheet which was preprinted with allowable proximity warnings. These same applicable measures of distance from adjacent roots or adjacent implants, as well as the platform relationship to the crestal bone have not materially changed since then.
On the other hand, the three-dimensional aspects of mandibular nerve loops, forward extensions, lingual fossae and sinus anatomy are not always readily apparent from a two-dimensional x ray and induced the added risk of unknown complications.
To make up for this deficiency, almost all cases were performed with a full flap and tissue reflection to expose the bone and ensure that the receiving structures were well positioned to avoid complications. The benefit of a guide preconstructed from a cone beam scan that allows minimal surgical flap approaches for single or a few implants in the same quadrant for comfort and healing as well as time savings during surgery are readily appreciated at this time.
The preparation phase was a completely hands on lab procedure. Using two stone pre op models, I obtained a periapical film, placed it over the first stone model and traced the root anatomy of the tooth to be extracted and of the adjacent teeth in order to avoid root contact during the surgery. I then outlined the coronal aspect of the implant on the soft tissue or crown surface.
The first model was then sectioned at the midpoint of the planned implant placement, and the root was traced into the sectioned model to allow 3-dimensional visualization of the surgical angle necessary to place the implant correctly in a buccal lingual direction.
A second model was then used to duplicate the root tracing as well as the implant trajectory on the buccal surface of the model. A 3 mm pilot hole was drilled into the planned implant site using the parameters defined by the root forms and the implant tracing on the model.
Using a guide pin, a premade metal pilot drill guide was positioned on the model over the guide pin, and light cured acrylic was formed over the metal drill guide and sculpted into the implant surgical guide to use during surgery. After curing and polishing, it was disinfected to use as a pilot guide.
At the surgical visit the premade drill guide was used for the initial pilot entrance, and a check x ray was taken and quick dipped in developing solution to check on the drill trajectory and proximity to structures to be avoided.
The next osteotomy drills were used in sequence without the benefit of the guide, and sometimes the mesial distal angulation of the implant would vary because of the difficult nature of holding the hand piece and the fore arm in the exact spatial position as was planned in the guide.
A final x-ray was taken of the final width drill. If necessary, a corrective osteotomy was performed, unfortunately in these cases, widening the osteotomy prevented higher insertion torques and necessitated a cover screw and a two-stage procedure uncovering. Another periapical x-ray of the inserted implant was taken before the flap was sutured and post op instructions given.
In the present time, digital cone beams, digital periapical x rays, printed surgical guides, and planning with software has replaced all of these manual steps, saving time, cost and providing increased accuracy and improved work flow.
Since I prefer to delegate the guide making to my lab, in about 5 minutes, I plan the initial implant placement in my Carestream software. Using my in-house cone beam scanner, I obtain the scan, and then trace the path of observation required. I then outline the course of the mandibular nerve for the lower arch. Using the built-in library, I select the appropriate brand, size and with of implant and orient it on the planned site, observing any anatomical areas to include or avoid. The plan is autosaved.
I then send the digital plan and a screen shot with the correct implant parameters to the lab. When it is returned from the lab with a surgical plan, I enjoy using the printed full drill guide with all the drill lengths and widths pre- determined for a rapid flap less implant placement which can take as little as 5 or 10 minutes. Every so often, the guide may need some adjustment to fit precisely. Also, sometimes the guided surgical kit will not fit in the back of the mouth when a patient cannot open widely enough to accommodate the increased height of the osteotomy drill. I these cases, is use the non-guided shorter drill set to encode the proper location and orientation of the osteotomy using the guided drill set but with shorter non-guided drills. I then finish the osteotomy to the proper length and insert the implant. I find the skills I learned prior to digital implant planning can sometimes come in handy when a patient simply cannot open wide enough for both the guide and any length drill. In these cases, I fall back on the old school methods.
With digital technology and minimal or no flap surgeries, patients report little to no pain post operatively, and the process is a wonderful addition to the modern dentists’ armamentarium.