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Written by Joseph Whitehouse, DDS Saturday, 01 November 2008 00:00
The evolution of dental implants has taken us from a very unpredictable time, when our brave colleagues would try new procedures in the 1970s, to the research of Bränemark that provided a wealth of knowledge leading to further technological developments and the predictable placement of implants that we are now experiencing. The fact that more than 90% of implants are successfully integrating to bone has led to the increased interest of general practitioners placing implants. Today, most research resembles the following excerpts: “…with a cumulative survival rate of 98.8%, a cumulative success rate of 95.7%, and a median marginal bone loss of 0.5 mm during the healing period”1; “The implant survival rate in the sample (was) 96.2%...”2
REFER IMPLANT PLACEMENT OR NOT?
With these impressive numbers in mind, and as more and more general dentists choose to place implants, a dilemma arises as to the complexity of which cases to do themselves and which ones to refer. With any new discipline, it takes education and time to gain the expertise to perform the basic procedure of creating a proper osteotomy. Each implant successfully placed leads to more confidence in placing the next one, in possibly a more difficult location.
My experience for the last 23 years in doing implant, restorative, and prosthetic work has been in referring patients out for implant placement. However, after listening to 2 fellow general practitioners, Dr. Bill Dapper and Dr. Nick Shubin, speak of their experiences in implant placement, it renewed my interest in performing the procedure. Understanding that more of my patients might accept implant placement if they could stay in my office to have the procedure, I took a series of 3 CAL-AID courses with Drs. Dapper and Shubin (California Academy of Implant Dentistry [calaid.com]) to learn implant placement techniques.
Even though these courses are well-done and thorough, any continuing education still leaves a participant with a further need to develop (through personal experience) the confidence that would lead to multiple-implant placement. However, with the tremendous advances in technology, I was able to transition to placing 6 implants (for a patient needing a bar overdenture) after placing only 4 individual implants. I believe in Freidrick von Shiller’s quote, “He that is overcautious will accomplish little.”
During a great BioHorizons Symposium (Spring 2006, Scottsdale, Ariz) Dr. Michael Klein presented the benefits of using a software system called Implant Logic (IL) (Implant Logic Systems [BioHorizons]) to process a CT scan. The resulting information is then used in the production of a surgical stent that accurately directs the angle and depth of an osteotomy for implant placement.
As can be seen in Figure 1, implants are placed virtually according to a patient’s bony/tissue morphology and the desired location. In each of the 4 screens, bone density is indicated (in Hounsfield units) by placing the pointer on any location. Knowing bone density enables the clinician to select the best location and specific implant best suited for that specific location. The possible need for a sinus lift can also be determined in advance. Each of these pieces of information can lead to the most minimally invasive techniques by giving the operator the ability to avoid such anatomical danger zones as the inferior alveolar canal, mental foramen, and the maxillary sinuses. Each manufacturer’s implants are available by diameter and length to drop into the IL software for creating an exact surgical stent (guide).
I am constantly looking for the most minimally invasive procedure to accomplish every phase of the dentistry performed. Since bone grafting is invasive, one of the most difficult issues in implantology is knowing how and when to bone graft effectively. Figure 1 shows the placement scheme used for the case presented in this article. As can be seen, the implants could be placed without compromising any of the significant anatomical areas, and no bone grafting was necessary in this case.
Without the IL software system, I would never have taken on this case, given my limited experience. I believe that the use of this technology can enable any dentist (with proper training) to be successful in placing implants. Furthermore, this technology will assist in the placement of implants in locations when it is necessary to know in advance if bone grafting, with or without sinus lifting, is necessary. Once one has IL, or another similar advanced software, any case that once seemed questionable from a traditional (without planning software) placement perspective, can be made much more manageable. It would seem that with a CT scan, which is becoming more and more available to us as a diagnostic option, this software may become the standard of care for use in these procedures due to its increasingly recognized role in optimal implant treatment planning and placement.
Figure 1. Implants are placed virtually, according to the patient’s bony/tissue morphology and desired location, utilizing a CT scan and an advanced software system (Implant Logic Systems [BioHorizons]).
Figure 2. This photo shows how a cross-bite would have to have been built into the case, necessitating a denture in this case.
Figure 3. Maxillary surgical stent, as fabricated from information provided utilizing the CT scan and Implant Logic software system.
Figure 4. Changeable inserts that fit into the stent collars make the system work; the collars are of the required diameter needed for each drill.
|Figure 5. The drill set was used to provide the initial drill-to-depth for each implant location.|
Figure 6. With the stent in place, a Waterlase (Biolase) was used to remove a circle of tissue in the middle of each site, and to begin the osteotomy, thus enabling the first drill to enter more accurately.
Figure 7. The first drill was then placed through the first insert and drilled to depth with an in and out motion with copious saline solution.
Figure 8. Photo showing the drill to depth.
Figure 9a and 9b. The osteotomies were completed, the surgical stent removed, and then the implants were installed. Since this was a one-stage procedure, tissue healing caps were used.
Figure 10. A temporary denture was pre-fabricated in the dental laboratory and modified directly at the chair to allow the healing caps to be passive.
Figure 11. Analogs were then attached to the impression posts with a tissue material that was applied before the stone pour.
Figure 12. A mock-resin bar (Triad [DENTSPLY]) created by the lab was placed to confirm that the bar fit passively, to see that the analogues were in their correct positions.
|Figure 13. While tightening one screw, it was discovered that the bar did not have a passive fit and needed to be cut between 2 implants and reassembled. After the sectioned bar was reassembled using Triad flowable (clear), it was used by the lab to reposition one analogue. (Repair was simple using the light-cured resin [Triad]).||
Figure 14. The split bar was then fabricated and tried in for passive fit.
Figure 15. A combination of Hader clips (Attachments International) and Lew (Park Dental Research) passive attachments were chosen to retain the overdenture in this case.
Figure 16. The ability to “lock” the denture into place meant the patient had total security.
|Figures 17a and 17b. Completed implant, bar-retained overdenture case.|
The insertion of the denture and the ability to “lock” it into place meant the patient had total security (Figure 16). The smile was pleasing to the patient, despite the compromise that had to be made due to the cross-bite built into the posterior because of the narrow maxillary arch (Figure 17a and 17b).
During my career, now spanning nearly 40 years, I have seen a great deal of technology (lasers, digital x-rays, CAD/CAM, digital impression, etc.) come into dentistry to make major differences in the ways our profession delivers care. The addition of CT scan-processing software has totally changed the ability of the general dentist to be directly involved in the placement of implants. The result of this will be the placement of more implants because patients usually desire to stay in the GP’s office for their care, when possible. The confidence level that the GP can project, when using imaging for treatment planning and stent construction, will facilitate the trust level needed by the patient to proceed.
My first case using this new technology was successful. The implants were placed almost 2 years ago, on January 16, 2007, and the patient has not required any adjustments. He continues to enjoy his smile and solid bite that was provided by the im-plant, bar-retained prosthesis.
- Behneke A, Behneke N, d’Hoedt B. A 5-year longitudinal study of the clinical effectiveness of ITI solid-screw implants in the treatment of mandibular edentulism. Int J Oral Maxillofac Implants. 2002;17:799-810.
- Mazzocchi A, Passi L, Moretti R. Retrospective analysis of 736 implants inserted without antibiotic therapy. J Oral Maxillofac Surg. 2007;65:2321-2323.
Dr. Whitehouse wishes to thank Bold Dental Laboratory for the fine work for this case.
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