IMPLANT OVERDENTURES: NEW CONCEPTS AND
UPDATED TECHNIQUES

It has been well documented that implant-related overdentures improve a patient’s quality of life. Furthermore, dental professionals have found that implant overdentures provide predictable resolution of the functional and aesthetic compromises associated with conventional dentures. Some of the specific benefits include improved prosthetic retention and stability, resulting in improved comfort eliminating soreness of the load-bearing tissues, and more stable facial aesthetics.

Because this type of prosthesis is implant retained and tissue supported, some cases including chronic mucosal tenderness or severe knife-edged ridges frequently require additional implants to reduce the load on the soft tissues. Therefore, classically two implants are all that is required in the mandible, but these special circumstances may require three to four mandibular implants. Three or four implants may also be necessary in cases of limited bone quality or quantity. Additional implants are frequently required in cases where narrow-diameter implants have been selected. It is interesting to note that the current standard of care does not require splinting of mandibular implants for overdenture use.

The current attachment of choice is the Locator because of decreased cost, increased hygiene accessibility, decreased space requirements and the fact that it is a resilient attachment. Additionally, Locator attachments can diverge by up to 40 degrees and still be of clinical value.

Unlike the mandible, the current trend is four implants in the maxilla in order to eliminate the need for full palatal coverage. In our practice we recommend a bar connector for the four implants due to the frequent finding of decreased bone quantity and quality, leading to the need for shorter implants coupled with the need for angulation correction. After designing the bar, Locator attachments can be tapped into the bar and used for retention. Generally three to four Locators incorporated into the bar are more than sufficient. If less than four splinted implants are suggested for the maxilla, then full palatal coverage as well as lower retention inserts are required. Therefore, two implants (non-splinted) with lower retention housings can generally be used in the maxilla as long as they are coupled with a well-fitting denture with full palatal coverage.

Restorative: Dr. Robert Bernstein / Colonial Dental Lab

UPDATE #2 ON BISPHOSPHONATE-ASSOCIATED
OSTEONECROSIS OF THE JAW (ONJ)

How should a dentist manage a patient receiving IV bisphosphonate therapy?

1. Management should be by a qualified dental specialist.
2. Pain management as required.
3. Report case to all appropriate authorities.
4. Management of infection
   • Oral antimicrobial rinses (0.12% Chlorhexidine).
   • Systemic antibiotics as required.
   • Surgical management.
     • Conservative or delayed.
     • Remove sharp exposed bone edges.
     • Bone sequestra should be removed without exposing uninvolved bone.
5. Dietary supplements to fulfill nutritional needs.
6. Controversial additional options.
   • Stop bisphosphonates.
   • Hyperbaric oxygen.

UPDATE #1 ON BISPHOSPHONATE-ASSOCIATED
OSTEONECROSIS OF THE JAW

In 2007, a multidisciplinary task force was formed by the American Society for Bone and Mineral Research on bisphosphonate-associated osteonecrosis of the jaw (ONJ). The full reference may be found at J. Bone Miner Res 2007; 22:1479-1491. This paper, I feel, provides some of the best information available on the subject. I will review the content of the paper here, but suggest everyone read the entire paper.

What is ONJ? ONJ is the presence of exposed bone in the maxillofacial region that does not heal within eight weeks after identification by a healthcare provider.

What is the risk of ONJ associated with oral bisphosphonates taken for osteoporosis? The risk is extremely low and is ranked as between 1 in 10,000 and 1 in 100,000 patient-treatment years. The condition is more common in the mandible than the maxilla.

What is the risk of ONJ in patients with cancer being treated with high doses of IV bisphosphonates? The risk is much higher and is in the range of 10% or less, depending on the duration of treatment.

What is the risk of ONJ in patients being treated with once-a-year IV Reclast for osteoporosis? Unknown.

What are the risk factors for ONJ? The risk factors are: IV bisphosphonates, cancer and associated anti-cancer therapy, dental extractions, oral surgery with bone manipulation, poor fitting dental appliances, intraoral trauma, duration of bisphosphonate treatment, glucocorticoids, alcohol and tobacco abuse, and pre-existing dental disease.

How should a dentist manage a patient already receiving (oral) bisphosphonate therapy?

• Informed consent regarding risks as outlined above and providing copies of articles, such as the one outlined above.
• Stress good oral hygiene with regular dental care.

For patients on long-term bisphosphonate therapy (currently defined as more than three years), the following precautions are advised:

• Patients with periodontal disease should be treated with non-surgical treatment. If surgery is required, then minimal bone exposure and re-contouring can be considered.
• Taking oral bisphosphonates is not a contraindication for dental implant placement. Informed consent should be provided and documented.
• Endodontic (root canal) treatment is preferable to endodontic surgery or extraction.
• While somewhat controversial, there is a suggestion to stop oral bisphosphonates for a period before and after invasive dental treatment

A further discussion of patients receiving IV bisphosphonates will be continued in my next newsletter.

OUR NEW WEBSITE

dralanmeltzer.com

Over the past eight months we have constructed what we feel is the most comprehensive implant and periodontal website available.

From the patients’ standpoint there is an abundance of comprehensive written information and videos to help your patients understand the nature of our practice and the services we provide.

Additionally, your patients can download their registration and health history forms and fill them out before they arrive in the office. HIPAA and financial policy forms can also be downloaded.

Your patients can contact us via our website and have any questions they may have answered. Of course, we still are available by telephone as well.

Do your patients need directions? They can simply type in their location, click and they will receive personalized turn-by-turn directions as well as a map and travel time.

From your perspective we maintain a library of articles and newsletters for your review. Coming soon will be dental “How Do I” videos. Such topics as fixture-level impression techniques, construction of clip locator dentures as well as other restorative procedures are just a click away. Back issues of my newsletters are also available.

Our website also provides free advertising for you. A list of all our referring colleagues remains available on our home page. If your name does not appear and you would like it listed, please e-mail us via a patient referral form, INFO FOR DOCTORS >Referral for Doctor or Simply click on “contact us” on the bottom of our home page. We would also be happy to provide a link to your website if you so desire.

We plan on updating our site regularly, providing the latest information for both you and your patients. We are interested in any suggestions for future additions which would prove helpful.

IMPLANT MAINTENANCE

As you know, it is my usual practice to provide you periodically with a short monograph on a timely dental topic. However, this month I had the opportunity to read a monograph written by a good friend, Anita Daniels, RDH. I felt that this is an outstanding review of an ideal implant maintenance visit. I hope that you will feel as I do. Also, please share the contents of this article with your hygiene staff.

MY TAKE ON MINI-IMPLANTS

Recently there has been a resurgence in the use of mini-implants (1.8-2.4mm in diameter). These implants were originally introduced as temporary implants and are now being used as a final solution for patients. This new idea is being promoted by some opinion leaders as an inexpensive solution for patients. My only experience with mini-implants has been the removal of fractured mini-implants, so the idea of taking a one or two-day course and starting to place these flaplessly left me scratching my head.

Keeping an open mind, I read a recent article* in Compendium. I would like to share my feelings after reviewing the article. The article tracked an impressive number of implants (2,514) over a 5-year period with an average evaluation period of slightly under 3 years. The average reported survival rate was 94.2%. While impressive, it falls about 3.5% shy of our 10-year survival rate with standard and wide-diameter implants. That represents a greater than 100% increase in failure rate. Additionally, 20 implants fractured during placement and were not included in the survival analysis. If included, that would increase the failure rate by an additional 0.8%. Furthermore, the authors preclude the placement of these mini-implants in type-4 bone and D-quantity bone. These criteria represent areas where most failures occur with standard implants. If I removed short implants and implants placed in poor quality bone and include immediately loaded mandibular implants, my published survival rate jumps to 99.38%** That represents about a 500% increase in failure rate using mini-implants.

Upon further review, the article stated that the average time period for failure was about 6.4 months. Today most standard implants are loaded at about 8 weeks. Published data with standard implants demonstrate that most failures occur during the 8-week period immediately following placement. This means that most failures occur with standard implants prior to fabrication of the prosthesis, while most mini-implant failures may occur during or after prosthesis fabrication.

Several other interesting facts surfaced. First, it took three years experience with MDI placement to achieve success rates over 90%. Second, mini-implants were far more successful supporting fixed bridges, which is an expensive restoration. Third, mini-implants used to support existing dentures had only an 88% survival rate. Fourth, a larger number of mini-implants are suggested as compared to standard diameter implants. Fifth, implants placed in the posterior maxilla were 3.3 times more likely to fail. Sixth, this implant is contraindicated in extraction sockets and, therefore, should not be used for immediate placement. Finally, mini- implants placed to support removable prostheses were 4.3 times more likely to fail.

After reviewing this article, I remain of the opinion that the use of standard implants will remain my treatment of choice. Let us never forget that there are patients attached to these implants, and the best way to manage a complication is to avoid it in the first place.

I compliment the authors for a well-written objective publication.

* Mini Dental Implants For Long Term Fixed and Removable Prosthetics. Shatkin TE, etal. Compendium, Vol 28, Number 2 pp 92-99.

** A 5 Year Life Table Analysis Of A Multi Center Study Involving Immediately Loaded Implants In The Edentulous Mandible. Testori T and Meltzer AM. Clin Oral Implant Research, Vol.115, 2004.

ENCODED ABUTMENTS

In this newsletter I would like to introduce a new concept in implant restoration. From this point forward it is no longer necessary to use an impression coping or snap cap to fabricate an implant restoration. We have worked closely with Biomet-3i to develop an encoded healing abutment system. Let me explain how this system works.

Following our usual protocol, either at the time of implant placement or at second-stage surgery, our office will install a healing abutment. The healing abutment will appear completely normal to you with the exception of some small hieroglyphics carved in the occlusal surface of the healing abutment. These markings carry a very specific code, which describes the exact location of the implant in four dimensions: buccal-lingual, mesial-distal, apical-occlusal as well as the timing of the internal hex.

When the patient arrives in your office, all that you need to do is rinse and dry the healing abutment in place. This will ensure a clean and accurate impression. Then, simply take a vinyl polysiloxane impression of the arch in a stock impression tray.

Take an alginate impression for a counter model, as well as providing a bite and shade. Forward the materials to your laboratory. They will pour and mount the casts. The material will be sent to 3i and then scanned. At 3i a virtual model is made and a custom abutment generated. Additionally, the encoded abutment data will permit 3i to fabricate a master cast.

The abutment and master cast are returned to the laboratory. The lab now fabricates a crown or crowns to exactly fit the cast and custom abutment(s). The abutment(s) can be made to your exact specifications or to a set of default specifications.

The master cast, crown and custom abutment are returned to you for installation. All you need to do is remove the encoded abutment for the first and only time, install the custom abutment, torque the abutment screw to 20 n/cm and cement the crown(s).

I hope this new innovation is both better for your patients as well as your practice.

Editorial Correction of Immediate Loading Update

Graph was mislabeled in the original letter sent last week. The corrected graph is below. Please reread the newsletter referring to the graph.

Editorial

As many of you are aware, Nobel Biocare has presented a technique which they call Teeth in an Hour. This technique has been heavily marketed and involves the production of a computer-generated surgical guide which may then be used to direct the placement of implants into either an edentulous mandible or maxilla. Following the placement of implants and the placement of abutments, a prefabricated final bridge is immediately placed. The technique, which combines computerized surgical and prosthetic treatment planning coupled with flapless surgery and the immediate placement of a final prosthesis in one sitting, seems on the surface to be a major step forward in implant dentistry. Some of its advantages include a one-stage flapless procedure, limited bleeding and post-operative pain, and the potential to treat fragile patients. However, there has been limited data to support this innovative approach. Preliminary data demonstrated success rates in the 95% range.

Recently at the Fifth World Congress of Osseointegration, which was held in Venice, Italy on February 15-17, 2007, Professor Bjorn Klinge presented a study on Nobel Biocares Teeth in an Hour concept. The presentation was titled Success and Failure Following Computer-Assisted Virtual Treatment Planning in Immediate Loading of Edentulous Patients. It should be noted that Professor Klinge of the Karolinska Institute is one of three independent MPA panelists for the NobelDirect implant investigation in Sweden. Professor Klinges single-centre data showed a 29% complication rate with up to three years follow-up. His data were based on the treatment of 31 arches and 175 implants. Professor Klinge went on to say that the 71% success rate remains an over estimate of true success since the current data are only clinical in nature and do not include radiographic data. Therefore, the true success rate is expected to be less than 71%. Dr. Klinge states that this technique remains in the exploratory phase.

I applaud Nobel Biocares visionary approach. However, considering that the gold standard for implant success remains in the 95% range, I personally have a difficult time adding this technique (71% success) to my implant protocol. It is my opinion that accelerated computer-guided implant protocols seem to be of clinical value. However, the practitioner must always perform a risk-benefit analysis prior to performing treatment. It appears to me that increasing failure rates by about 500% in an effort to accelerate treatment is not something with which I am comfortable.

In our practice we continue to offer immediate implant placement and immediate fixed provisionalization using an approach supported by published clinical data. In one such paper published in COIR, Dr. Testori and I demonstrated a 99.38% implant success rate over a five-year period with immediate placement and restoration. While we continue to research combining computer-guided implant surgery and restoration, it remains part of a research protocol within our practice and should not be viewed as the standard of care until sufficient data are available.

Let us never lose sight as we move forward that there are people attached to these implants.

Note: NobelGuide, Teeth in an Hour and NobelDirect are trademarked by Nobel Biocare.

Testori T, Meltzer A, Fabbro MD, Troiano M, Francetti L, Weinstein RL. Immediate occlusal loading of Osseotite implants in the lower edentulous jaw: A multicentre prospective study. Clin Oral Impl Res 2004; 15:278-284.

This monograph will address crestal bone preservation techniques. As I discussed in my last newsletter, when an implant is exposed to the oral environment there is a natural adjustment in the position of the crestal bone. The bone adjusts apically and laterally about 1.5 millimeters. This has been classically described as bone loss to the first thread. As discussed previously, this natural phenomenon impacts soft tissue morphology and aesthetics.

One way to overcome this problem is through the use of platform switching. Platform switching is defined as the placement of an undersized prosthetic component on an oversized or expanded platform.

Notice the classic formation of biologic width on the mesial implant. Bone remodeling has moved the point of bone to implant contact to the first thread. Note how the bone level on the distal implant holds at the platform level due to the impact of platform switching on the formation of biologic width.

How does platform switching alter the formation of biologic width?

By moving the implant abutment junction away from the edge of the implant, a space is provided to shield the bone from the inflammatory process associated with the junction. This physiologic inflammatory process has been described and documented by Ericsson and others. It is this inflammatory reaction which is the trigger for the formation of biologic width. Platform switching provides a space for the inflammatory cells to reside without impacting the bone. Therefore, platform switching eliminates crestal bone remodeling, providing additional bone to implant contact and eliminating changes in soft tissue morphology usually associated with the formation of biologic width.

The classic location of the inflammatory cells.

The location of inflammatory cells with platform switching. Note how the platform provides a space for the inflammatory cells so it does not impact the crestal bone.