A 41-Year History of a Mandibular Subperiosteal Implant

Schou, L. Pallesen, E. Hjørting-Hansen, C. S. Pedersen, B. Fibaek

Full text link: https://pubmed.ncbi.nlm.nih.gov/11168208/

A 41-Year History of a Mandibular Subperiosteal Implant

1. Scientific Reference

• Study title: A 41-year history of a mandibular subperiosteal implant
• Authors: Schou, L. Pallesen, E. Hjørting-Hansen, C. S. Pedersen, B. Fibaek
• Scientific journal: Not specified in the information provided.
• Year of publication: Not specified in the information provided.
• DOI: Not specified in the information provided.
• PMID: 11168208

2. Scientific Background

Subperiosteal implants represent an early chapter in the development of dental implantology. According to the authors, this type of implant was first described in the 1940s. By the time this report was published, its long-term clinical performance contrasted unfavourably with the documented outcomes of endosseous osseointegrated implants.

One particular difficulty in assessing the very long-term consequences of subperiosteal implants is that problematic devices were often removed relatively soon after placement. This case therefore provides an unusual perspective. The mandibular subperiosteal implant had been placed in 1957 and remained present for decades despite recurrent local complications.

The clinical relevance of the report lies primarily in documenting what occurred when a persistently complicated implant was retained over an exceptionally long period. It also illustrates how chronic implant-related problems and prolonged absence of clinical surveillance may ultimately affect mandibular bone anatomy and complicate subsequent implant rehabilitation.

3. Study Objective

The purpose of this report was to document the complete 41-year clinical history of a mandibular subperiosteal implant, with particular attention to the consequences associated with retaining the device despite recurrent complications over several decades.

The authors followed the clinical course through to eventual implant removal and described the implications of the resulting mandibular bone loss for subsequent treatment with osseointegrated implants.

4. Methodology

This publication is a long-term clinical case report involving a mandibular subperiosteal implant placed in 1957. The documented clinical history extends over 41 years.

The available information describes recurrent implant exposure, inflammation, infection and fistula formation. Complete removal of the implant was proposed but refused by the patient in 1973. This was followed by a 25-year period without clinical follow-up, after which the patient was reassessed in 1998.

No standardized clinical or radiographic assessment protocol is described in the abstract provided. Quantitative measurements of mandibular bone resorption are also not reported. There was no control group or comparative treatment arm, consistent with the nature of a single-patient case report.

5. Main Results

The clinical course was marked by persistent complications involving the mandibular subperiosteal implant. These included implant exposure and recurrent inflammatory and infectious manifestations, together with fistula formation.

Following the patient’s refusal of complete implant removal in 1973, no clinical monitoring was performed for 25 years. When the patient was reassessed in 1998, extensive mandibular resorption was identified. The severity of the clinical situation ultimately resulted in complete removal of the subperiosteal implant.

The consequences extended beyond removal of the original device. According to the report, the remaining mandibular anatomy did not permit placement of osseointegrated endosseous implants without prior extensive autogenous bone grafting.

The case therefore documents a severe long-term outcome in which persistent complications surrounding a retained subperiosteal implant were ultimately associated with major loss of mandibular bone and substantially increased complexity of subsequent implant rehabilitation.

6. Clinical Analysis

The principal clinical value of this publication lies in its exceptionally long observation period rather than in its ability to evaluate treatment effectiveness. It provides a rare description of the consequences observed when a subperiosteal implant with recurrent complications remained in place for several decades.

Persistent exposure, inflammation, infection and fistula formation are central features of the reported clinical history. The subsequent finding of extensive mandibular resorption following 25 years without clinical monitoring gives particular importance to the authors’ emphasis on regular surveillance of patients carrying these older implant systems.

The case is also relevant from a reconstructive perspective. By the time the implant was completely removed, the available mandibular bone was considered inadequate for direct placement of osseointegrated implants. Extensive autogenous bone grafting would have been required before such implant rehabilitation could be contemplated.

However, the findings must be interpreted according to the study design. A single case cannot establish the incidence of complications associated with subperiosteal implants, quantify the risk of severe mandibular resorption, or determine how frequently a comparable clinical course might occur. The report instead provides a detailed example of an adverse long-term evolution and highlights the potential consequences of leaving persistent implant-related complications unresolved.

7. Clinical Applications

The findings are particularly relevant to the assessment and long-term monitoring of patients who still carry historical subperiosteal implants, especially when implant exposure, inflammation, infection or fistula formation is present.

The case also emphasizes the importance of evaluating residual bone anatomy when removal of a longstanding implant becomes necessary. In this patient, extensive mandibular resorption had direct consequences for future oral rehabilitation, as conventional placement of osseointegrated implants could not be performed without major autogenous bone grafting.

Based on this clinical history, the authors emphasize regular follow-up for patients with subperiosteal implants and support implant removal when complications remain persistent. These conclusions should nevertheless be understood within the limited evidence provided by an individual case report.

8. Level of Evidence, Limitations and Transparency

This publication is a case report and therefore provides a limited level of evidence for determining the overall safety, effectiveness or prognosis of subperiosteal implant therapy. Its scientific value primarily derives from the unusually long clinical history and the documentation of severe complications occurring over several decades.

The single-patient design prevents statistical analysis and does not allow the frequency of such complications to be estimated. In addition, the 25-year period without clinical follow-up limits the ability to reconstruct precisely when and how the mandibular resorption progressed.

The abstract does not provide quantitative bone-loss measurements or a standardized assessment protocol. No conflicts of interest or relationships with implant manufacturers are reported in the information provided.

9. Key Study Points

• Study type: Clinical case report.
• Level of evidence: Low, due to the descriptive single-patient design.
• Population or studies analysed: One clinical case.
• Number of patients or implants: One patient; one mandibular subperiosteal implant reported.
• Follow-up duration: 41-year clinical history.
• Main outcome assessed: Long-term evolution of a mandibular subperiosteal implant retained despite persistent complications.
• Main result: Recurrent implant exposure, inflammation, infection and fistula formation, followed by extensive mandibular resorption identified after a prolonged period without clinical monitoring.
• Scientific conclusion: The authors emphasize regular follow-up of patients with subperiosteal implants and advocate removal when persistent complications occur.
• Main limitations: Single case, absence of a control group, 25-year interruption in clinical monitoring, and limited methodological information in the available abstract.

10. Scientific Impact

The importance of this publication is primarily historical and clinical. It documents an exceptionally long course involving a type of implant that had become uncommon and provides insight into the potential consequences of retaining a subperiosteal implant despite persistent local complications.

Of particular relevance to implant dentistry and oral surgery is the relationship between the longstanding complication history and the severe mandibular bone loss eventually observed. The resulting anatomy substantially complicated subsequent rehabilitation because endosseous osseointegrated implant placement would have required extensive autogenous bone reconstruction.

The report cannot establish complication rates or provide comparative evidence between implant techniques. Its scientific contribution instead lies in documenting an unusual long-term clinical trajectory. As such, it reinforces the importance of continued surveillance, timely assessment of persistent biological complications and consideration of their potential impact on future reconstructive and implant treatment options.

11. Editorial Conclusion

This 41-year case history provides a rare perspective on the long-term evolution of a mandibular subperiosteal implant complicated by recurrent exposure, inflammation, infection and fistula formation. The extensive mandibular resorption ultimately observed had major consequences for subsequent implant rehabilitation. Although the evidence is necessarily limited by the single-case design, the report remains clinically instructive regarding long-term surveillance and the management of persistent complications associated with historical implant systems.