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Maintenance Considerations for the Mandibular Two-Implant Overdenture

Both fixed and removable prostheses require maintenance and this must be discussed with patients prior to treatment. Maintenance of the two-implant overdenture is generally less complicated, less expensive, and easier for both the patient and the dentist than maintenance of a fixed implant prosthesis.



Patients should be instructed to maintain peri-implant health by simple brushing around the abutments with a standard toothbrush. Aftercare of the overdenture is similar to that of a conventional denture with regard to brushing. Some of the commercial denture cleaning products, however, may adversely affect the retentive elements. Instructions should be given regarding the use of specific corrosive products (Figure 1).



Recent consensus indicates that the overall prosthodontic maintenance requirements of mandibular overdenture treatment are greater during the first year of service than in subsequent years.1 The following is an outline of the most common and consistent complications and patient requirements as reported in the literature.


Denture Adjustment

Alteration of the denture base contour as a result of pain and discomfort is reported to be the most common initial problem following treatment. An increased awareness of the maxillary denture may also be observed and/or the maxillary denture may be perceived as unsatisfactory as compared to the now more stable lower prosthesis. Adjustments to the maxillary denture may also be necessary due to an increase in the loading of the overdenture.


Maintenance of Retentive Devices

Clips, springs, and other retentive elements may loosen within the acrylic base or require replacement. These are the most common complications/repairs, and they are of clinical significance. The key points are as follows:

  • Initial studies indicated a high level of loose abutments with ball attachments for the unsplinted design. Due to redesigned one-piece components and higher preload values, however, the attachments no longer exhibit this characteristic.
  • All patients are expected to present with decreased retention force over time, leading to the following conclusions:

1) It is generally desirable to begin with the most retentive components that still allow the patient to remove the prosthesis. This maintains a higher level of retention over time and allows further alteration of retention to address a patient’s specific needs. This principle should be balanced with the goal of choosing components that are easy to adjust (ie, reactivate) or replace without the need for complicated laboratory support (ie, reline).

2) Implant parallelism and proper position will have a significant impact on long-term prosthetic maintenance needs (ie, nonparalleled implants) and will generally require more maintenance than more paralleled implants.

3) A metal housing supporting a plastic retentive matrix is mandatory in terms of simplicity to alter/change retention as compared to a matrix directly attached to the acrylic. In the latter case, a closed-mouth complete arch-impression technique is utilized in which the position of the attachments and soft tissue are registered. This involves laboratory support with additional costs.

4) The use of metal (eg, titanium, gold) for ball attachments has been implicated in the wear of the head of the matrix. With further prospective evaluation, this observation may lead to favoring the use of plastic matrices.

Overdenture Relines

The need for reline of the overdenture may be indicated by the presence of one or more of the following specific criteria;

  • Repeated activation and replacement of the matrices;
  • Lack of stability in an anteroposterior direction;
  • Repeated adjustments of the contour of the fitting surface; and
  • Increase in the accumulation of food beneath the overdenture.


Before changing a retentive element, the need for relining must first be confirmed with a material on the fitting surface of the denture. If this thickness is greater than about 1 mm, then a reline may be necessary. The primary objective of relining the overdenture is to limit extensive rotation and to maintain well-distributed contacts between the intaglio surface of the denture and the mucosa.

It is also important to consider how long the patient has been edentulous in anticipating the need for relines (ie, the newly edentulous patient should be evaluated carefully within the first year when most bone loss occurs by comparison with a patient who has been edentulous for many years, in whom bone loss has already stabilized).


Overdenture Fracture

Because fracture may occur as a result of insufficient bulk of overdenture acrylic, the question arises as to whether it is necessary to use a cast metal base for the two-implant overdenture. In view of the desire to minimize restorative cost to the patient and of success rates with sufficient bulk of acrylic, it is consensus that a metal base or stiffener should not be considered a standard procedure except in the case of the minimally resorbed mandible, in which the acrylic base will be excessively thin. In most cases, however, this may be avoided with careful planning.


Prosthetic Tooth Fracture

Excessively thin prosthetic teeth may fracture. This may be avoided with careful planning and proper implant positions.

Successful application of the surgical principles will have a profound impact on the ease of fabrication of definitive prosthesis as well as long-term maintenance considerations.

Soft Tissue Changes

Mucositis and hyperplasia have been observed more commonly among patients restored with splinted bar overdentures, while decubitus ulcers have been observed more often among those restored with nonsplinted overdentures.



A regimen of at least annual patient recalls is recommended to allow evaluation of retentive elements, hard and soft tissue changes, and fit of denture base (eg, poor adaptation will increase rotation and increase wear of components); soft tissue maintenance by a hygienist; evaluation of occlusion; and radiographic follow-up. Although the frequency of post-insertion prosthodontic maintenance is not possible to predict, with careful case selection and meticulous planning, these needs may be minimized. More frequent patient recalls may be indicated for those with poor hygiene around the two implants. It is important to check for occlusal changes, stability, and soft tissue health in the initial three to six months.



  1. Payne AG, Solomons YF. The prosthodontic maintenance requirements of mandibular mucosa-and implant-supported overdentures: A review of the literature. Int J Prosthodont 2000;13(3):238-243.


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