Why Overdentures?

Implant-Retained Overdentures as Prosthetic Solutions for the 21st Century  

Dr. Stefan Holst

Despite the fact that patients considering implant treatment tend to contemplate a fixed restoration first, numerous studies have proven that implant-retained overdentures can also significantly improve masticatory function and, at the same time, fulfill patients’ expectations and demands.^1-3

An awareness of the need to restore aesthetic appearance is not limited to the partially edentulous. Indeed, it is of great importance to fully edentulous patients as well.^2,4  

The most conspicuous aesthetic impairment these patients have to face affects extraoral appearances. Substantial atrophy of the alveolar ridge requires extensive support of the peri-oral musculature if facial harmony is to be reestablished.^2,3

While this can be achieved technically with a fixed restoration, the resulting design of the prosthesis may significantly impair hygiene accessibility. It is important to differentiate between two different types of removable restorations. The implant-retained, mucosa-supported overdenture is mostly supported by two interforaminal implants with various anchoring mechanisms such as round or Dolder bars, ball or magnetic, or other extracoronal attachments.^3,5

An alternative to the resilient treatment modality can be found in the implant-supported removable prosthesis, which is a rigidly anchored prostheses purely supported by implants (four or more fixtures).⁶ The implant-supported removable prosthesis is stabilized on extended (CAD/CAM-milled) bars, which prevent rotational movements of the prosthesis.⁷

The advantage of this retention and support design is that the restoration is comparable to a fixed prosthesis. It provides for a stable occlusal plane and prosthesis position when functional forces are applied.⁶

Factors to Consider

Repair options and maintenance needs are additional factors that need to be taken into consideration when decisions are being made about the design and retention mechanism of a superstructure.^2,3 The most frequently reported technical complication identified for implant-retained, mucosa-supported restorations is loosening of the retentive mechanism (e.g., wear of matrices) requiring the replacement of components.⁸

However, the introduction of CAD/CAM-milled, high-precision bar elements for implant-supported removable prostheses has resulted in a significant reduction in the need for post-insertion maintenance.⁷ This also holds true for the rigid anchoring of implant overdentures by telescopic attachments. Clinical studies have demonstrated high implant success rates concomitant with only a minor degree of prosthodontic maintenance effort.

In general, both fixed and fixed-removable implant restorations are viable treatment options for edentulous patients (Table).^1-3 Clinical long-term outcome is comparable if patient-specific characteristics are taken into account during treatment planning and execution.

Decisive factors for either solution include the patient’s age and expressed expectations, the amount of missing hard and soft tissue, the manual skills of the patient and his or her financial situation.^2,3

*Clinical Associate Professor, Friedrich-Alexander-University, and Associate Editor of the journal Quintessence International.

Adapted with permission from Nobel Biocare News Vol. 14, No.2, 2012.

References:  

1. Feine JS, Carolsson GE, Awad MA, et al.  The McGill consensus statement on overdentures. Mandibular two-implant overdentures as first choice standard of care for edentulous patients. Montreal, Quebec, May 24-25, 2002; Int J Maxillofac Impl 2002;17(4):601-602.

2. Feine JS, Carolsson GE. Implant Overdentures: The Standard of Care for Edentulous Patients. Carol Stream, IL: Quintessence Publishing, 2003.

3. Carpentieri JR, Tarnow DP. The Mandibular Two-Implant Overdenture: First-Choice Standard of Care for the Edentulous Denture Patient. Mahwah, NJ: Montage Media Corporation, 2007.

4. Fiske J, Davis DM, Frances C, Gelbier S. The emotional impact of tooth loss in edentulous people. Brit Dent J 1998;184(2):90-93.

5. Gotfredson K, Holm B. Implant-supported mandibular overdentures retained with ball or bar attachments: A randomized 5-year study. Int J Prosthodont 2000;13(2):125-130.

6. Malo P, de Araújo Nobre M, Lopes A, et al. A longitudinal study of the survival of All-on-4 implants in the mandible with up to 10 years of follow-up. J Am Dent Assoc 2011;142(3):310-320.

7. Drago C, Sadarriaga RL, Domagala D, Almasri R. Volumetric determination of the amount of misfit in CAD/CAM and cast implant frameworks: a multicenter laboratory study. Int J Oral Maxillofac Impl 2010;25(5):920-929.

8. Fromentin O, Lassauzay C, Nader SA, et al. Wear of matrix overdenture attachments after one to eight years of clinical use. J Prosthet Dent 2012;107(3):191-198.