Treatment of the edentulous mandible
GORDON J. CHRISTENSEN, D.D.S., M.S.D., Ph.D.
In my opinion, the most common debilitating oral condition existing on a routine level is edentulism in the mandible. Many have estimated that about 40 million patients in the United States are edentulous.1 Most patients who have the unfortunate experience of coping with lower dentures are dissatisfied with them. However, these same patients are often satisfied with their upper dentures.
Dentists are familiar with the patient complaint that the upper denture is acceptable, but that the previous dentist made a poor lower denture. These patients expect the new dentist to make a great lower denture, but it is the uncommon dentist who can make a new lower denture that satisfies the patient better than the old one. In my opinion, this ubiquitous problem is not improving. The mandibular denture procedure is difficult, and dental school curricula have minimal removable prosthodontic education. Many new dentists state that they have not had significant prosthodontic education in dental school, and that they avoid making complete dentures.
Is there a solution to ensure the success of prosthodontic treatment for edentulous mandibles? I contend that edentulous mandibles can be treated with success, but that successful treatment concepts require a change in the treatment planning approach, as well as the acquisition of some new techniques.
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TREATMENT PLANNING APPROACH
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Patients enter dental offices with minimal education about dental therapy alternatives. People who have edentulous mandibles expect to receive new dentures that will satisfy their needs better than did their previous dentures. Since the acceptance of lower dentures is not one of the most successful areas of dentistry, why not try a different approach? The following patient education and treatment planning approach has been highly successful for me in a prosthodontic practice that attracts the most dissatisfied of patients.
First, educate patients about the relatively unsatisfactory acceptance rate of lower dentures. Tell them that there are other alternatives for treatment of their edentulous mandible that have been shown to have higher acceptance by patients. Before increasing their expectations, you must obtain some educational materials. I have described my opinions on the importance of educational aids.2,3 To properly inform patients about methods of treating edentulous mandibles, I suggest that you use models, casts, photographs, videotapes, DVDs and patient testimonials (written or oral).
I consider the following treatment procedures to be acceptable for patients with edentulous mandibles who have been dissatisfied with previous, technically acceptable mandibular dentures. The same treatments are desirable for other patients who have compromised clinical situations.
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TYPES OF TREATMENT
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Overdenture supported by two implants.
An overdenture supported by two implants is the least expensive and simplest alternative. I have used this treatment for hundreds of patients, and I have yet to have a patient say that he or she does not like the therapy. I have described the technique in JADA.4 The updated procedure for this alternative follows:
- – Place the two implants in the lower canine areas and temporarily reline the lower denture with soft chairside liner to provide adequate denture service for the implant integration time.
- – Allow about four months for the implants to integrate into the bone. Another option is to place the implants and load them immediately. Depending on your beliefs and your experience, you may use either technique. I prefer four months of healing, because of my predictable, positive experience with this approach.
- – Uncover the implants and place two spherical abutments on the implants. These O-ring attachments are available from many companies (for example, Attachments International).
- – Allow about two weeks for the gingival tissues to heal around the O-ring abutments. It is preferable to have at least 1 millimeter of the metal abutment platform supragingival, so that soft tissue can adapt well to the abutment.
- – Make an overdenture in the conventional manner. Rubber O rings that fit over the metal spheres on the abutments are placed in the denture before the processing procedure.
The box
, "Typical U.S. Fees for Overdenture Procedures," presents usual U.S. fees for these services and the others that follow in this article. The fees are based on estimates as reported by Atlanta Dental Consultants.5
Overdenture retained by a bar attached to implants and clips attached to the bar.
This is my favorite alternative for edentulous mandibles. With this type of overdenture, the patient’s facial form can be developed to any reasonable appearance the patient desires; dentures can be cleaned when taken out of the mouth; implants can be cleaned when the prosthesis is removed; the prosthesis can be easily repaired; and chewing efficiency is nearly the same as that with natural teeth.
- – Place two to four implants in the anterior mandible. I prefer these implants to be in the areas of teeth nos. 21, 22, 27 and 28.
- – Allow the implants to integrate into the bone for about four months.
- – Uncover the implants and place healing caps on them.
- – Allow about two weeks for the tissue to heal around the healing caps.
- – Make an impression of the edentulous mandible and the implant locations.
- – Have a bar made to attach to the implants and fit the edentulous ridge. The bar should extend posteriorly from the implants a variable distance, ranging from 3 mm to 5 or 6 mm. I prefer the bar to be placed directly on the soft tissue, so that the denture is not hollow, and the center of gravity of the supporting bar and clip is directed apically toward the bone.
- – Make another impression of the edentulous ridge with the bar in place.
- – Perform a typical centric jaw relation registration as with a normal denture.
- – Try the waxed-up denture and teeth into the mouth.
- – Make the denture, containing gold alloy clips that fit onto the bar. A typical overdenture usually has about six to eight clips.
- – Seat the denture and adjust it.
The usual fee for this procedure5 is shown in the box
, "Typical U.S. Fees for Overdenture Procedures."
Fixed-detachable prosthesis retained by implants.
Although many edentulous patients think that they want this type of rehabilitation, they should have adequate education to understand the advantages and disadvantages of the therapy. Because of the necessity for patients to perform adequate oral hygiene, fixed-detachable prostheses cannot have as much denture base contour and fullness as removable implant-supported prostheses. Therefore, the patient’s esthetic expectations may not be realized. Although the prosthesis is detachable by the dentist, pros-thesis removal and replacement requires significant time and a great deal of expertise. If an implant fails, or the prosthesis fails, the entire treatment may be jeopardized. On the positive side, the implant prosthesis has the "feel" and chewing effectiveness of natural teeth. Most patients find their fixed-detachable prosthesis to be excellent therapy. In my opinion, the only major negative characteristics of this therapy are the inability to make the prosthesis’ contour completely normal in some patients, and the overall cost of this treatment is the highest of all of the alternatives.
- – Place five or more implants from tooth area 21 to tooth area 28.
- – Allow the implants to integrate into the bone for about four months.
- – Uncover the implants and place healing caps.
- – Allow about two weeks for the soft tissue to heal around the healing caps.
- – Make an impression of the edentulous arch and the implant locations.
- – Make a metal framework that fits the implants exactly and that has enough retentive features to retain subsequently placed resin. This framework will retain and support the acrylic resin denture base that holds the teeth in place.
- – Try in the metal framework.
- – Make wax occlusion rims on the metal framework.
- – Make a centric jaw relation registration.
- – Set up the teeth on the framework.
- – Try the teeth in the patient’s mouth.
- – Process the denture.
- – Seat the fixed-detachable hybrid prosthesis.
The typical fees for a fixed-detachable prosthesis and the necessary implants5 are shown in the box, "Typical U.S. Fees for Overdenture Procedures."
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CONCLUSIONS
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Conventional removable complete dentures for edentulous mandibular arches are not well-accepted by many patients. There are several alternatives for edentulous mandibular arches other than extraction of teeth and placement of conventional dentures. The treatment options described in this article are overdentures supported by two implants and their respective abutments; overdentures supported by two or more implants and retained by a bar and several metal clips; and fixed-detachable prostheses retained by about six implants.
Because of the significantly increased patient satisfaction associated with these alternatives, dentists should be motivated to educate patients about the alternatives and become clinically competent in these important concepts.
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Dr. Christensen is co-founder and senior consultant of Clinical Research Associates, 3707 N. Canyon Road, Suite No. 7A, Provo, Utah 84604, and is a member of JADA’s editorial board. He has a master’s degree in restorative dentistry and a doctorate in education and psychology. He is board-certified in prosthodontics. Address reprint requests to Dr. Christensen.
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REFERENCES
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- Bolender C, Zarb G, Carlsson G, eds. Boucher’s prosthodontic treatment for edentulous patients. 11th ed. St. Louis Mosby–Year Book; 1997:46–7.
- Christensen GJ. Informing patients about treatment alternatives. JADA 1999;130(5):730–2.
- Christensen GJ. Improving treatment plan acceptance using staff-driven diagnostic data collection. JADA 1999;120(11):1629–31.
- Christensen GJ. The most needed application for dental implants. JADA 1994;125: 743–6.
- Limoli TM Jr., ed. [Annual U.S. dental fee schedule review.] Dental Insurance Today (newsletter) 2000;14(2):3–7.
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