By Paul L. Child Jr., DMD, CDT

For more on this topic, go to www.dentaleconomics.com and search using the following key words: implant retained removable prostheses, RPD, Paul L. Child.

I often attend presentations that feature case after case of implant-retained prostheses, and those cases cost patients well over $50,000. I leave wondering when those patients will show up at my practice, or how I can sell my existing patients on these bigger cases. Many dentists tell me about similar experiences — they return to their practices on Monday, excited about what they learned, but baffled about how to implement and provide these types of prostheses.

There are many solutions to this all-to-common scenario, such as increased marketing, networking with specialists, advanced education and clinical training, and more. However, by only directing our attention on the "big" cases, we miss an entire segment of the population that can result in improved patient satisfaction, increased revenue, and increased referrals to a growing implant practice.

It is estimated that over 30% of the U.S. population is in need of multiple implants to support a simple implant retained overdenture. Many more are in need of one to two implants for the partially edentulous dentition.

There is no question that providing a few implants for an edentulous patient can increase his or her satisfaction level significantly. However, those that are often ignored as excellent candidates for implants are the partially edentulous patients that have limited funds and require a removable partial denture (RPD). There are numerous reasons why dentists dislike RPDs.

Common challenges of RPDs

? Lack of interest by dentists

? Deemed old-fashioned

? Lack of acceptance and compliance by patients

? Poor understanding of biomechanics

? Very little input from dentist on design

? Difficult framework try-in and adjustments

? Decreased longevity in moderate to high-risk patients – lost teeth, mobility, decay

? Undesirable due to poor financial returns

Implant supported RPDs

Class I and II distal extension RPDs can easily be transformed into tooth and implant supported/retained RPDs, often without the unsightly clasps, or can be shortened for stability, not retention (see Figs. 1-6). The result is a patient with a higher level of satisfaction who is more likely to wear the prosthesis, has increased esthetics, and most important, becomes a believer in your dentistry and returns for future treatment.

Fig. 1: RPD without clasps on four implants.

Providing an implant supported RPD requires teamwork. The team consists of: a skilled technician that can assist you in surveying the casts and planning for rest seats, guide planes, and an adequate path of insertion for the future implants and prepared teeth; a surgeon who can place implants that are prosthetically driven and relatively parallel to each other and the path of insertion; and you, the restorative clinician who can put it all together.

Fig. 2: Intaglio surface of RPD with lingual plate and four Locator (Zest) attachments

After successfully planning and delivering a few of these restorations, you will discover the significant impact you can make on your patients' lives, as well as your own level of satisfaction in your practice, including financially.

Fig. 3: Occlusal of combined standard-narrow (mini) diameter implant retained RPD. Two mini implants were placed in area of premolars and a 5 mm diameter Neoss implant placed in area of molars.

A key component to treating these patients is thorough patient education. Help patients understand that together, we are planning for the future by providing a few implants now to support and retain the RPD. If you expect a patient to lose a few more teeth in the next five to 10 years, explain that a tooth can be added to the prosthesis, or another implant can be placed to support a new RPD.

Fig. 4: Intaglio of RPD with o-ring attatchments — 3M ESPE for Mini Dental Implants (MDI) and ORS (Attachments International) for standard diameter implant.

With time, some of these patients become fully edentulous and already have four to six implants per arch to easily support an implant overdenture or a fixed implant prosthesis.

Implant supported/ retained overdentures

Along with gold and perhaps the rubber dam, the simple mandibular, two-implant supported/retained overdenture is as close as our profession gets to a universal standard of care (in patients that can receive implants).

Fig. 5: Final retracted view of prosthesis; note minimal show of clasps.

For patients who have to go through the misery of full-mouth extractions (without the funds for a more elaborate implant prosthesis), immediate interim dentures (that often don't fit and are poorly retained by the residual and shrinking arch), and the trauma of the procedure, the implant supported/retained overdenture can be a welcome relief.

Fig. 6: Example of mini clasp used for stability of prosthesis rather than retention.

Below are tips and techniques for providing affordable and effective overdentures.

Selective socket preservation. At the time of an extraction, especially full arch combined with delivery of an immediate interim denture, selectively graft areas where future implants may be placed (see Fig. 7).

Fig. 7: Mandibular edentulous arch after full mouth extractions and selective socket preservation of mandibular canines only.

There are many excellent options to choose from, the most common being allograft (e.g., MinerOss by BioHorizons, Puros by Zimmer, LifeNet Oragraft by Salvin) and alloplasts (e.g., NanoGen by Orthogen, CaSO4 Calcium Sulfate Hemihydrate by Ace Surgical, BondBone by MIS).

Narrow diameter implants. Although some surgeons scoff at the use of mini implants, when placed properly they can be highly successful. Most important, for patients who may not be able to afford extensive grafting or larger diameter implants, mini implants are truly a miracle (see Figs. 8 and 9).

Fig. 8: Surgical placement of two Mini Dental Implants (3M ESPE) in non-grafted areas immediately after placement of standard diameter implants (Neoss) in previously grafted canine areas.

Mini implants have exploded in popularity as many clinicians and manufacturers are discovering their many uses and high patient acceptance. Mini implants are the "gateway drug" to implant dentistry for many clinicians seeking to diversify their restorative options. Almost every implant company now offers mini implants.

Fig. 9: Attachment housings in place prior to chairside pickup with dual-cured ERA Pick-up (Sterngold).

Even companies that are traditionally considered implant companies, such as Glidewell Laboratories and Henry Schein, are now providing these options along with the most well-known providers of mini implants, 3M ESPE, Sterngold, Intra-lock, and Dentatus.

Attachments. Clinicians Report (Nov. 2011) compared six different attachments for use with implants. These included ERA (Sterngold), GPS (Implant Direct), Locator (Zest), MDI O-Ball (3M ESPE), ORS (Attachments International), and Saturno (Zest). Interesting features and results were discovered regarding retention, wear, resiliency, longevity, non-parallelism, and costs.

Fig. 10: Intaglio of denture with adequate space cleared for pick-up of attachment housing. Note vent holes on lingual of denture and undercuts in spaces for housing to rely upon both adhesive and mechanical retention.

Although Locators and ERA have been among the most used attachments, newer implant/abutment/attachment options are available with desirable features.

An example is the new GPS from Implant Direct that can be machined as a one-piece implant (GoDirect) or as a separate abutment (straight or angled). The former offers an internal connection for use with other abutments or conversion to a bar/splinted implants. O-rings remain highly popular because they provide the most resiliency (vertical movement), thus distributing forces to soft tissue and implants.

Fig. 11: Intaglio of denture after pick-up of attachment housings – both o-rings (3M ESPE) and Locators (Zest).

Pick-up. This can be accomplished chairside or by sending the prosthesis to the lab. However, the chairside procedure is simple and allows the clinician to place the proper load on the attachment to minimize occlusal adjustments, overloading the implant and/or attachment system, and future prosthesis fractures or complications.

Light but even pressure should be used during the pick-up procedure, especially with implant supported RPDs, to avoid the rests not fully seating after "rebound" of the attachment due to resiliency.

Use of Fit Checker (GC America) or a similar material should be used to make sure that no aspect of the attachment housing is in contact with any portion of the prosthesis.

Fig. 12: Final complete maxillary and implant retained-supported mandibular dentures with Phonares denture teeth (Ivoclar Vivadent).

Mechanical undercuts should be made in the relief to allow both mechanical and adhesive requirements with the pick-up material, such as ERA Pick-Up by Sterngold (see Figures 10-12).

Conclusion

Dentistry is a clinical profession with a business component. As a profession, we have obligations to treat patients effectively and without discrimination. Tunnel vision of grand cases that are self-serving may leave you feeling not only shallow, but realizing that you may have lost a significant amount of revenue by ignoring the often overlooked, yet abundant quantity of patients that could benefit from implant retained removable prostheses.

Dr. Paul L. Child Jr. is a prosthodontist and a certified dental technician. Dr. Child lectures nationally and internationally on all areas of dentistry, with an emphasis on new and emerging technologies. He maintains membership in many professional associations and academies, and is on the editorial board of several journals. Dr. Child can be contacted at toni@pccdental.com.