Forty Years of Experience with Subperiosteal Implant Dentures in 41 Edentulous Patients

R. L. Bodine, R. T. Yanase, A. Bodine

Full text link: https://pubmed.ncbi.nlm.nih.gov/8850449/

Forty Years of Experience with Subperiosteal Implant Dentures in 41 Edentulous Patients

1. Scientific Reference

• Study title: Forty years of experience with subperiosteal implant dentures in 41 edentulous patients
• Authors: R. L. Bodine, R. T. Yanase, A. Bodine
• Scientific journal: Not specified in the information provided.
• Year of publication: 1996
• PMID: 8850449
• DOI: 10.1016/S0022-3913(96)90414-X

2. Scientific Background

This study provides an unusually long clinical perspective on mandibular subperiosteal implants used to support and retain complete dentures in edentulous patients. The devices included in the series were placed between 1952 and 1971, with patient monitoring extending through 1992.

The scientific value of this report lies primarily in the duration of observation. In implant dentistry, long-term function is an important component of clinical assessment, particularly when evaluating a treatment intended to provide durable prosthetic rehabilitation.

The study specifically addresses complete mandibular edentulism and highlights the potential relevance of subperiosteal implants in patients with resorbed mandibles. Rather than providing a comparison with other implant or reconstructive approaches, the report documents the long-term clinical course of a specific implant-supported prosthetic strategy over several decades.

3. Study Objective

The study aimed to examine the long-term clinical course of complete mandibular dentures supported and retained by subperiosteal implants.

The investigators assessed the functional status of the implants over prolonged follow-up and documented when loss of function occurred. The study also provides information on differences in performance between earlier and later implant designs used during the period covered by this clinical experience.

4. Methodology

The clinical series included 41 patients who consecutively received complete mandibular dentures supported and retained by subperiosteal implants. Implant placement took place between 1952 and 1971, and the patients were monitored through 1992.

Implant outcomes were classified into three groups: devices that became nonfunctional, implants that remained functional, and implants for which functional observation ended prematurely because of patient death or another cause unrelated to implant condition.

The abstract indicates that follow-up variables and methods were defined by the investigators, although their specific details are not available in the information provided.

No control group or direct comparison with an alternative implant or prosthetic treatment is reported in the available abstract.

5. Main Results

Of the 41 implants evaluated, 14 (34%) were ultimately classified as nonfunctional. Nine implants (22%) remained functional, while follow-up of 18 implants (44%) ended because of patient death or another event unrelated to implant status.

The timing of implant failure provides an important perspective on the findings. The reported cumulative proportion of failures was 5% at 5 years, 22% at 10 years, and 34% at 20 years. No additional failures were recorded beyond the 20-year point within this series.

Among the implants that remained in service, nine had been functioning for 21 to 36 years after placement. Five of these devices had remained functional for more than 30 years.

The investigators also reported a clear difference between implant generations, with devices developed later in their clinical experience performing substantially better than earlier implants.

6. Clinical Analysis

The principal clinical contribution of this study is its exceptionally prolonged observation period. The findings demonstrate that long-term function extending over several decades was achievable in a subset of patients treated with mandibular subperiosteal implants. In particular, the presence of five implants still functioning beyond 30 years provides clinically relevant evidence of durability in selected cases within this cohort.

The temporal distribution of failures is equally important. Although 34% of the implants were classified as failed by 20 years, no subsequent failures were reported after that point. This should be interpreted as an observation within this particular clinical series rather than evidence that an implant remaining functional for 20 years will necessarily continue to perform successfully thereafter.

The reported superiority of later implant designs is another relevant finding. It suggests that technical development over the course of the investigators’ experience may have influenced clinical performance. However, the abstract does not provide enough information to determine which specific design modifications or clinical factors accounted for this improvement.

From a treatment perspective, the authors considered mandibular subperiosteal implants potentially relevant for selected patients, particularly those with resorbed mandibles. This interpretation should remain proportional to the study design. The findings document long-term clinical experience but do not establish superiority over alternative implant or reconstructive strategies.

7. Clinical Applications

The findings are specifically relevant to the prosthetic rehabilitation of completely edentulous mandibular patients using a subperiosteal implant to provide denture support and retention.

The clinical situation explicitly highlighted by the authors is the resorbed mandible. Their experience suggests that mandibular subperiosteal implants could be considered in selected patients presenting with this anatomical condition.

The available data, however, do not support comparisons with endosseous dental implants, bone grafting procedures, or other reconstructive approaches. Similarly, no conclusions can be drawn regarding digital implant planning, guided surgery, CAD/CAM workflows, or other technologies not addressed in the information provided.

The study should therefore be interpreted within the specific clinical and historical framework of the treatment protocol investigated.

8. Level of Evidence, Limitations, and Transparency

Based on the information provided, this publication represents a long-term observational clinical series involving 41 consecutively treated patients. Such a study can provide valuable evidence regarding long-term clinical behavior, but its level of evidence is insufficient to establish therapeutic superiority or support definitive treatment recommendations.

An important consideration is that follow-up of 18 implants (44%) was terminated by patient death or another cause unrelated to implant condition. This proportion must be taken into account when interpreting the long-term outcome figures.

No control group or direct treatment comparison is described in the available abstract. Detailed definitions of failure and other follow-up variables are also not available in the material provided.

Conflicts of interest or manufacturer relationships: No information is provided regarding conflicts of interest, financial relationships, or author affiliations with implant manufacturers.

9. Key Study Points

• Study type: Long-term observational clinical series.
• Level of evidence: Limited; non-comparative clinical evidence based on the information provided.
• Population: Completely edentulous mandibular patients.
• Number of patients: 41.
• Number of implants/prosthetic rehabilitations: 41 mandibular subperiosteal implant-supported and retained dentures.
• Implant placement period: 1952–1971.
• Follow-up: Patients were monitored through 1992; some implants remained functional for 21–36 years.
• Primary outcome assessed: Long-term functional status of the subperiosteal implants.
• Main result: 14 implants (34%) became nonfunctional, 9 (22%) remained functional, and follow-up of 18 (44%) ended because of death or another implant-unrelated cause.
• Very long-term finding: Five implants remained functional for more than 30 years.
• Scientific conclusion: The findings led the authors to consider mandibular subperiosteal implants as a possible option for selected patients, particularly those with resorbed mandibles.
• Main limitations: Small clinical series, observational design, no reported comparator, and a substantial proportion of follow-up terminated for reasons unrelated to implant condition.
• Conflicts of interest: Not specified in the information provided.

10. Scientific Impact

The main contribution of this publication is its documentation of the very long-term clinical behavior of mandibular subperiosteal implant-supported dentures. Few aspects of the study are as informative as the duration of observation itself: several implants remained functional for decades, with five exceeding 30 years of service.

The study also provides evidence that outcomes were not uniform throughout the investigators’ experience. Later implant designs were reported to perform better than earlier devices, indicating that technical evolution may have been an important component of long-term clinical performance. The available abstract, however, does not identify the individual factors responsible for this difference.

Scientifically, the study is best regarded as long-term observational evidence rather than comparative proof of treatment efficacy. Its value lies in documenting what was clinically achievable with this particular rehabilitation strategy and in providing historical evidence on the longevity of subperiosteal implants in edentulous mandibular patients.

11. Editorial Conclusion

This study offers a distinctive long-term perspective on subperiosteal implant-supported rehabilitation of the edentulous mandible. The continued function of several implants beyond 20 years—and of five devices for more than 30 years—is the most notable observation. These findings remain clinically and historically informative, particularly in relation to patients with resorbed mandibles. Nevertheless, the observational and non-comparative nature of the evidence requires cautious interpretation and does not support conclusions regarding superiority over other implant treatment strategies.