Inside Dentistry
May 2007
Volume 3, Issue 5

An eight-year follow-up to arandomized clinical trial of aftercare and cost-analysis with three types of mandibular implant-retained overdentures

Howard E. Strassler, DMD

Stoker GT, Wismeijer D, van Waas MA. J Dent Res. 2007;86(3):276-280.


Mandibular implant overdentures increase satisfaction and the quality of life of edentulous individuals. Long-term aftercare and costs may depend on the type of overdentures. One hundred and ten individuals received one of 3 types of implant-retained overdentures, randomly assigned, and were evaluated with respect to aftercare and costs. The follow-up time was 8 years, with only seven drop-outs. No significant differences (Kruskal-Wallis test) were observed for direct costs of aftercare (p = 0.94). The initial costs constituted 75% of the total costs and were significantly higher in the group with a bar on 4 implants, compared with the group with a bar on 2 implants and the group with ball attachments on 2 implants (p = 0.018). The last group needed a significantly higher number of prosthodontist-patient aftercare contacts, mostly for readjustment of the retentive system. It can be concluded that an overdenture with a bar on 2 implants might be the most efficient in the long term.


The use of implants to improve lower denture retention has helped overcome this major challenge to the restorative dentist. There are significant anatomic limitations of the ridge when fabricating a mandibular denture. In many cases, patients who have been edentulous for extended periods of time have minimal anatomic features to the jaw and ridge to work with. Over this past decade, the successes of mandibular overdenture retention with the use of a variety of implants have created a standard of care for mandibular denture retention that includes the placement of an implant-supported denture. These overdentures offer improved denture stability, function, speech, and patient satisfaction. This article provides important information to better understand the level of aftercare and costs a patient and clinician would need to be prepared for depending on which type of design was selected to improve the retention of a lower denture. While past studies have provided information on the costs of the initial stage of treatment and costs of aftercare over periods of up to 1 year, the real question is what happens over longer periods of time. This study provides information and recommendations based on 8 years of aftercare. Aftercare was defined as all care and maintenance provided during the evaluation period to include regular check-ups. These consisted of surgical, prosthetic, and/or oral hygiene measures taken to keep peri-implant tissues healthy and to ensure optimal denture function. At 8 years, 94% of the patients were still part of the study. Three different implant-retained denture designs were evaluated. Based on the data collected from this excellent study, aftercare with the overdenture retained by a bar with two implants was significantly lower than the other designs. Also, it was noted that initial costs were 71% to 78% of the total cost. There is no doubt that the original cost for the bar with four implants was also significantly more expensive than the other two alternatives. The conclusions of this paper took the results of patient satisfaction into account with the costs to make the recommendation that the two implants interconnected by a single bar might be the first treatment of choice, with high cost effectiveness, efficacy, and proven stability for a long-term period.

About the Author

Howard E. Strassler, DMD
Professor and Director of Operative Dentistry
Department of Endodontics, Prosthodontics and Operative Dentistry
University of Maryland Dental School, Baltimore, Maryland

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