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he edentulous patient has not disappeared. While the prevalence of edentulism is less than what it was 20 years ago, about 33 percent of Americans older than 65 years of age were completely edentulous as of 2000.1,2 When all Americans older than 18 years of age are considered, approximately 10 percent are completely without teeth.1 There are disparities in the rate of edentulism among racial and When planning ethnic groups, with Mexican-Americans treatment for least likely to lose all of their teeth.1 patients with Edentulism is one of a few dental condiedentulous tions for which state-specific data exist. These data reveal a wide variation in mandibles, the percentages of the population aged clinicians 65 and older who have no teeth, from a should consider low of 13.9 percent in Hawaii to a high the implant- of 47.9 percent in West Virginia.2 The classical treatment plan for the supported edentulous patient is the complete prosthesis. removable maxillary and mandibular denture. This treatment is relatively inexpensive in comparison with fixed implant-supported prostheses, but it has several drawbacks (Box 1). Like all dental restorative procedures, a complete removable denture requires extensive attention to detail if an excellent clinical result is to be achieved. Depending on the shape of the regional ridge, the denture may be unstable or inadequately retained, leaving the patient dissatisfied

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JAMES H. DOUNDOULAKIS, D.M.D., M.S.; STEVEN E. ECKERT, D.D.S.; CLARENCE C. LINDQUIST, D.D.S.; MARJORIE K. JEFFCOAT, D.M.D.

CON

The implant-supported overdenture as an alternative to the complete mandibular denture

Background. Approximately one-third of Americans older than 65 years of age are fully edenA D A J tulous, requiring replace✷ ✷  ment of missing teeth. While the conventional denture may meet the N C needs of many patients, A UING EDU 1 R TICLE others require more retention, stability, function and esthetics, especially in the mandible. The implant-supported prosthesis is an alternative to the conventional removable denture. Methods. This article describes the strengths of the implant-supported mandibular overdenture. The authors also outline the risks of this approach. They performed a review of recent literature to summarize the reported success rate of implants used to support a mandibular overdenture. Results. The literature review indicates that implants placed in the anterior mandible (anterior to the foramen) have a success rate better than 95 percent. Patients have reported a high degree of satisfaction with the implant-supported overdenture. Conclusions. The literature indicates that implant-supported overdentures in the mandible provide predictable results with improved stability, retention, function and patient satisfaction compared with conventional dentures. Implants placed in the anterior mandible have a success rate equal to or greater than 95 percent. Clinical Implications. When planning treatment for patients with edentulous mandibles, clinicians should consider the implant-supported prosthesis.

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with the functional result. The rate of residual ridge resorption in edentulous patients who do not have tooth replacements is highly variable and may be as much as several millimeters per year. This resorption can render the current prosthesis inadequate in terms of both function and esthetics and can lead to the necessity of fabricating a new denture. Over time,

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BOX 1

denture (Figure 2) has good stability and retention, and patients DISADVANTAGES OF THE COMPLETE who have received them have REMOVABLE DENTURE. reported improved function and satisfaction.3 dExtensive detail required for proper fabrication Another benefit of implantdLack of stability (especially in mandible) dLack of retention (especially in mandible) supported prostheses is suggested dContinued loss of alveolar bone leading to further instability and lack by preliminary data indicating of retention that after receiving implants, dPatients using such dentures may be led to believe professional dental care no longer is needed patients may eat a diet with more dLack of chewing function when ill-fitting fiber (M.K. Jeffcoat, D.M.D., dSocial concerns (slippage, unnatural appearance) unpublished data, 2003). If this is proven, the implant-supported BOX 2 denture would make an important contribution to general health and ADVANTAGES OF THE IMPLANT-SUPPORTED well-being. OVERDENTURE. Other studies have measured the rate of residual ridge resorpdAs few as two to four implants may be used for support tion in the five years after implant dGood stability dGood retention placement. The rate of resorption dImproved function is decreased significantly from the dImproved esthetics rates seen with conventional dendReduced residual ridge resorption dSimplest implant-supported prosthesis tures, and recent research has dPossible incorporation of existing denture into the new prosthesis shown that the height of the posterior ridge increases with continued use of implant-supported prostheses.4 occlusion, esthetics and function may be compromised. Although patients in studies are not directly comPerhaps one of the greatest drawbacks to the parable to the population as a whole, patients full denture is the misconception to which it gives with implant-supported prostheses return for rise, on the patient’s part, that dental care no visits with the same practitioner at a very high longer is needed. Such patients deny themselves rate.5 In one study, this rate exceeded 95 percent not only routine maintenance of their prostheses over seven years, permitting detection of two canbut also the advantages of cancer screening. cers in a study population of 120.5 A 2002 conToday’s patients have high expectations for sensus statement developed by scientists and oral health; providing a traditional denture that expert clinicians at a symposium on the efficacy of eventually becomes an ill-fitting prosthesis does overdentures for the treatment of edentulous not help meet these expectations. The implantpatients held at McGill University in Montreal, supported denture is one solution to these Quebec, Canada, lists a mandibular overdenture problems. as the first choice in treating edentulous patients.6 ADVANTAGES OF THE IMPLANTSuccess rates. Implants no longer are considSUPPORTED PROSTHESIS ered experimental. The table shows representaThe implant-supported overdenture has many tive clinical trials over the past six years.3,5,7-13 We advantages. Although as few as two to four performed a library search for implant clinical implants may be used for support (Box 2), it is trials in the anterior mandible reported in beneficial to use more than two implants in the English; the table shows the primary author, size unlikely event that one of the implants fails to of study, study design and representative results function during the patient’s life span. Implant of each study we found. (This article is not placement surgery is relatively simple to perform intended to provide extensive statistical metaand, in experienced hands, may take less than an analysis.) Most of the trials were longitudinal hour. Many options are available for retention of studies of cohorts of patients treated according to the prosthesis, including magnets, clips, bars and the sample protocol. We evaluated data from balls (Figure 1). The resultant implant-supported these studies and found that they demonstrate a 1456

JADA, Vol. 134, November 2003 Copyright ©2003 American Dental Association. All rights reserved.


COSMETIC

Figure 1. Two implants (with ball retainers) support a mandibular denture.

& RESTORATIVE CARE

Figure 2. The clinical results of the implant placement shown in Figure 1: an implant-supported mandibular denture and a conventional maxillary denture.

TABLE

associated with REPRESENTATIVE IMPLANT CLINICAL TRIAL RESULTS. implant placement are outlined in Box 3.14,15 TYPE OF STUDY RESULT AUTHOR Risks include postop3 erative bleeding, Higher patient satisfaction Awad and colleagues Randomized Clinical than with conventional Trial numbness if the denture mandibular nerve is Buser and colleagues7 Survival rate: > 95 percent disturbed, infection for screws Prospective and lack of osseointeTawse-Smith and Success rate: 95.8 percent gration. The risks can colleagues8 Prospective be minimized with Meijer and colleagues9 Success rate: 97 percent Prospective, Multicenter proper training and 10 experience. Case Moberg and colleagues Success rate: submerged Prospective implants, 97.9 percent; selection and diagnonsubmerged implants, 96.8 nosis is the key to sucpercent cess with implant proRodriguez and Success rate: 92.6 percent Prospective, Multicenter 11 cedures, as with all colleagues dental procedures. Morris and Ochi12 Success rate: hydroxyapatite, Prospective, Multicenter Other risk factors or HA, cylinder, 97.5 percent; titanium, or Ti, screw, 99.4 also may affect the percent outcome of the Jeffcoat and colleagues5 Success rate: HA, 99 percent; Prospective, Multicenter implant-supported Ti screw, 96 percent prosthesis. Smoking is Bergendal and Success rate: 100 percent Prospective a risk factor for longEngquist13 term implant success. Patients who smoke are more likely to experience infection and/or prosuccess rate above 95 percent in the anterior gressive alveolar bone loss, which ultimately may mandible. It is noteworthy that among the lead to implant loss. A smoking cessation plan sources of support for these studies were many including periodic assessment of cotinine levels different implant manufacturers and the U.S. may be ordered to track long-term exposure to government. Furthermore, the success rate exceeds the rate prescribed for the ADA Seal of tobacco. Acceptance by the ADA Council on Scientific Untreated periodontitis also is a risk factor for Affairs. the failure of dental implants. Obviously, fully Risks. No surgical procedure, including the edentulous patients do not have periodontitis, but placement of implants, is without risk. The risks even after the extraction of a single tooth with JADA, Vol. 134, November 2003 Copyright Š2003 American Dental Association. All rights reserved.

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BOX 3

supported prostheses should be considered in planning treatment for the fully edentulous patient. ■

RISK FACTORS FOR FAILURE OF DENTAL IMPLANTS. dSmoking dFactors that affect healing of bone (such as diabetes, use of steroids) dUntreated periodontal disease dAnatomy (if bone in recipient site is inadequate, grafting may be necessary)

dPoor bone quality dInadequate practitioner training, experience or both dPatient compliance concerns periodontal disease, the site may harbor pathogenic bacteria that may lead to periimplantitis. Factors that may influence the healing or potential infection of the implant recipient site also may affect the outcome. Uncontrolled diabetes and use of drugs such as steroids need to be carefully considered in the treatment plan, and the clinician may need to adjust time to loading accordingly. Anatomy and bone quality also affect the outcome and ease of surgical placement of implants. Implants need adequate bone height and width for placement. If the native bone at the recipient site is inadequate to accept the implant, bone grafts—with or without guided bone regeneration—must be considered. Bone quality, which is related to density of the trabecular bone, usually is not a problem in the anterior mandible. Other segments of the alveolar bone, such as the posterior maxilla, are more likely to have lower bone density, which can limit implant stability and osseointegration. With proper diagnosis and treatment planning, the limitations and risks of implant placement are manageable. Good communication between the surgical and restorative members of the team is a necessity. High-quality training and experience in implant surgery and restorative care are fundamental to delivering quality care. CONCLUSION

The literature and clinical experience indicate that the implant-supported prosthesis provides predictable results with improved stability and function and a high degree of satisfaction as compared with conventional removable dentures. Clinical studies in the literature in which implants were used in the mandible anterior to the foramen indicate that the success rate for implants in the lower mandible is 95 percent or greater. These data indicate that implant1458

Dr. Doundoulakis maintains a private practice in cosmetic dental rehabilitation in New York City. He also is section chief, Maxillofacial Prosthetics, and attending dentist, St. Luke’sRoosevelt Hospital Center, New York City; and attending and assistant clinical professor, New York/Presbyterian, The University Hospitals of Columbia and Cornell, New York City. Address reprint requests to Dr. Doundoulakis at 3 E. 66th St., New York, N.Y. 10021, e-mail “cosmeticdental@att.net”.

Dr. Eckert is an associate professor of dentistry, Mayo Medical School, Rochester, Minn. Dr. Lindquist maintains a private practice in oral and maxillofacial surgery, Chevy Chase, Md., and Washington. Dr. Jeffcoat is dean, University of Pennsylvania School of Dental Medicine, Philadelphia, and the editor of JADA. 1. U.S. Surgeon General. Oral health in America: A report of the surgeon general. Part two: What is the status of oral health in America? Rockville, Md.: U.S. Dept. of Health and Human Services, U.S. Public Health Service, Office of the Surgeon General; 2000. Available at: “www.nidcr.nih.gov/sgr/sgrohweb/part2.htm”. Accessed Oct. 2, 2003. 2. Tomar S. Total tooth loss among persons aged greater than or equal to 65 years: selected states, 1995-1997. MMWR Morb Mortal Wkly Rep 1997;48:206-10. 3. Awad MA, Lund JP, Dufresne E, Feine JS. Comparing the efficacy of mandibular implant-retained overdentures and conventional dentures among middle-aged edentulous patients: satisfaction and functional assessment. Int J Prosth 2003;16:117-22. 4. Reddy MS, Geurs NC, Wang IC, et al. Mandibular growth following implant restoration: does Wolff’s law apply to residual ridge resorption? Int J Periodontics Restorative Dent 2002;22(4):315-21. 5. Jeffcoat MK, McGlumphy EA, Reddy MS, Geurs NC, Proskin HM. A comparison of hydroxyapatite (HA)-coated threaded, HA-coated cylindric, and titanium threaded endosseous dental implants. Int J Oral Maxillfac Implants 2003;18:406-10. 6. Thomason JM. The McGill Consensus Statement on Overdentures. Mandibular 2-implant overdentures as first choice standard of care for edentulous patients. Eur J Prosthodon Restor Dent 2002;10(3):95-6. 7. Buser D, Mericske-Stern R, Bernard JP, et al. Long-term evaluation of non-submerged ITI implants, part 1: 8-year life table analysis of a prospective multi-center study with 2359 implants. Clin Oral Implants Res 1997;8(3):161-72. 8. Tawse-Smith A, Perio C, Payne AG, Kumara R, Thomson WM. One-stage operative procedure using two different implant systems: a prospective study on implant overdentures in the edentulous mandible. Clin Implant Dent Relat Res 2001;3(4):185-93. 9. Meijer HJ, Geertman ME, Raghoebar GM, Kwakman JM. Implantretained mandibular overdentures: 6-year results of a multicenter clinical trial on 3 different implant systems. J Oral Maxillofac Surg 2001; 59(11):1260-8. 10. Moberg LE, Kondell PA, Sagulin GB, Bolin A, Heimdahl A, Gynther GW. Branemark System and ITI Dental Implant System for treatment of mandibular edentulism: a comparative randomized study— 3-year follow-up. Clin Oral Implants Res 2001;12:450-61. 11. Rodriguez AM, Orenstein IH, Morris HF, Ochi S. Survival of various implant-supported prosthesis designs following 36 months of clinical function. Ann Periodontol 2000;5(1):101-8. 12. Morris HF, Ochi S. Survival and stability (PTVs) of six implant designs from placement to 36 months. Ann Periodontol 2000;5(1):15-21. 13. Bergendal T, Engquist B. Implant-supported overdentures: a longitudinal prospective study. Int J Oral Maxillofac Implants 1998; 13:253-62. 14. Quirynen M, De Soete M, van Steenberghe D. Infectious risks for oral implants: a review of the literature. Clin Oral Implants Res 2002;13(1):1-19. 15. Tonetti MS. Determination of the success and failure of root-form osseointegrated dental implants. Adv Dental Res 1999:13:173-80.

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Cosmetics and Restorative Care