Squamous Cell Carcinoma Around a Maxillary Subperiosteal Implant: The Association Between Chronic Mechanical Irritation and Peri-Implantitis – A Case Report

Takuma Watanabe, Dai Kawahara, Ryo Inoue, Tomoki Kato, Noboru Ishihara, Hidemichi Kamiya, Kazuhisa Bessho.

Full text link: https://pubmed.ncbi.nlm.nih.gov/35235079/

Squamous Cell Carcinoma Around a Maxillary Subperiosteal Implant: The Association Between Chronic Mechanical Irritation and Peri-Implantitis – A Case Report

1. Scientific Reference

• Study Title: Squamous cell carcinoma around a subperiosteal implant in the maxilla and the association of chronic mechanical irritation and peri-implantitis: a case report.
• Authors: Takuma Watanabe, Dai Kawahara, Ryo Inoue, Tomoki Kato, Noboru Ishihara, Hidemichi Kamiya, Kazuhisa Bessho.
• Journal: International Journal of Implant Dentistry.
• Year of Publication: 2022.
• DOI: 10.1186/s40729-022-00409-3.

2. Scientific Background

Subperiosteal implants were historically developed as a treatment option for patients with severe maxillary or mandibular bone atrophy who lacked sufficient bone volume for conventional endosseous dental implants. Although advances in bone augmentation, zygomatic implants, and digital implant planning have considerably reduced their use, many patients continue to function with subperiosteal implants placed decades ago. These long-term rehabilitations require careful clinical monitoring because biological and mechanical complications may develop over time.

Among the complications associated with subperiosteal implants, framework exposure, implant mobility, chronic infection, fistula formation, and progressive bone resorption are well recognized. Whether persistent peri-implant inflammation combined with chronic mechanical trauma may contribute to oral carcinogenesis remains an uncommon but clinically significant question. This case report explores that possibility through the presentation of a patient who developed an oral squamous cell carcinoma adjacent to a maxillary subperiosteal implant after years of implant instability and chronic peri-implant disease. The report contributes to the understanding of rare long-term biological complications in implant dentistry while emphasizing the importance of continuous maintenance of complex implant-supported rehabilitations.

3. Study Objective

The purpose of this case report was to describe an unusual occurrence of squamous cell carcinoma arising around a maxillary subperiosteal implant that had been functioning for approximately twenty years. The authors aimed to examine the potential contribution of chronic mechanical irritation caused by implant mobility together with long-standing peri-implantitis as possible physical and biological factors involved in carcinogenesis. They also sought to discuss these findings in a patient who did not present the major conventional risk factors for oral cancer, such as tobacco or alcohol consumption.

4. Methodology

This publication is a single-patient case report, representing the lowest level of clinical evidence but providing valuable documentation of an exceptionally rare clinical presentation. The report describes the diagnostic work-up and management of a 74-year-old man who had received a maxillary subperiosteal implant approximately twenty years earlier to restore posterior occlusion in a severely atrophic maxilla.

The diagnostic assessment included a comprehensive clinical examination, panoramic radiography, computed tomography (CT), and an incisional biopsy of the palatal lesion. Following confirmation of squamous cell carcinoma, the patient underwent neoadjuvant chemotherapy, bilateral neck dissection, and partial maxillectomy with complete removal of the subperiosteal implant. Histopathological evaluation was performed on the resected specimen. In addition, the retrieved implant underwent energy-dispersive X-ray spectroscopy (EDX) to determine its elemental composition and scanning electron microscopy (SEM) to evaluate surface alterations. The study is descriptive in nature and does not include a control group or comparative analysis, which is consistent with its case report design.

5. Main Findings

Clinical examination revealed severe mobility of the subperiosteal implant associated with an indurated palatal ulcer, an oro-palatal fistula, and exposure of the metallic framework. Radiographic evaluation demonstrated extensive maxillary bone loss surrounding the implant, near-complete loosening of one retaining screw, and bilateral maxillary sinusitis. Histopathological analysis of the biopsy confirmed a diagnosis of squamous cell carcinoma (cT4aN2cM0).

Following neoadjuvant chemotherapy, the patient underwent surgical treatment consisting of bilateral neck dissection, partial maxillary resection, and removal of the implant. Microscopic examination demonstrated a well-differentiated, highly keratinized squamous cell carcinoma with extensive invasion into both soft tissues and bone. Examination of the explanted implant revealed substantial plaque and calculus deposits on the bone-contacting surface. EDX analysis indicated that the framework had been fabricated from commercially pure titanium but detected no titanium within the resected tissue specimen. SEM examination identified several microcracks compatible with localized pitting corrosion. Based on these observations, the authors considered chronic inflammation and long-standing mechanical irritation to be more plausible contributing factors than direct titanium deposition in this particular case.

6. Clinical Analysis

This case highlights an exceptionally uncommon clinical scenario in which multiple long-term implant-related complications appear to have created a biological environment favorable to the development of oral squamous cell carcinoma. Importantly, the authors do not claim that the subperiosteal implant itself caused the malignancy. Instead, they propose that prolonged mechanical trauma and persistent peri-implant inflammation may have acted together as potential contributing factors. Given the nature of a single case report, these observations should be interpreted as hypothesis-generating rather than evidence of causation.

The clinical history is particularly informative. Shortly after implant placement, one of the two retaining screws was lost, compromising the stability of the prosthesis. Over subsequent years, progressive implant mobility resulted in repeated contact between the metallic framework and the palatal soft tissues. This chronic irritation occurred alongside framework exposure, fistula formation, and untreated peri-implantitis that persisted for several years without regular maintenance. The authors suggest that this prolonged combination of physical trauma and chronic inflammation may have established conditions favorable for malignant transformation.

Analysis of the retrieved implant further supports this interpretation. Extensive plaque and calculus accumulation on the bone-contacting surface indicates long-standing bacterial colonization consistent with chronic peri-implant disease. Although SEM identified localized surface microcracks suggestive of pitting corrosion, EDX analysis failed to detect titanium within the tumor specimen. Consequently, the authors considered inflammatory and mechanical factors to be more relevant than direct titanium-related carcinogenic mechanisms in this individual case.

From a clinical perspective, this report reinforces an important principle in implant dentistry: persistent implant mobility, chronic fistulation, framework exposure, or non-healing peri-implant ulceration should never be regarded as routine mechanical complications alone. When these findings persist despite conventional management, clinicians should consider comprehensive diagnostic evaluation, including biopsy when clinically indicated, to exclude malignant disease. Although extremely rare, this case underscores the importance of long-term surveillance of aging subperiosteal implants and other complex implant-supported rehabilitations.

7. Clinical Applications

Although based on a single clinical observation, this report provides several practical messages for clinicians involved in implant dentistry, oral surgery, and the long-term management of complex implant-supported rehabilitations.

First, it highlights the importance of lifelong follow-up for patients who still carry subperiosteal implants, particularly those placed before the widespread adoption of modern endosseous implant systems. Mechanical complications such as framework exposure, implant mobility, and progressive loss of retention should not be regarded solely as prosthetic problems, as they may coexist with chronic biological complications requiring prompt intervention.

The case also emphasizes that persistent peri-implant inflammation associated with chronic ulceration, fistula formation, or exposed implant components warrants careful clinical evaluation. When these lesions fail to resolve or exhibit atypical characteristics, histopathological assessment should be considered to exclude malignant transformation. While this report does not establish a causal relationship between peri-implantitis and oral squamous cell carcinoma, it reinforces the need for thorough differential diagnosis in patients presenting with chronic peri-implant soft tissue lesions.

Finally, the findings underline the importance of regular maintenance programs aimed at controlling peri-implant biofilm and identifying mechanical failures before they progress to advanced biological complications. These observations are particularly relevant for patients rehabilitated with historical implant designs that remain in function decades after placement.

8. Level of Evidence, Limitations, and Transparency

This publication is a case report, representing a low level of clinical evidence within the hierarchy of evidence-based medicine. Its primary value lies in documenting a previously unreported clinical presentation and generating hypotheses regarding possible mechanisms linking chronic implant-related complications with oral carcinogenesis. The findings should therefore be interpreted as observational rather than confirmatory.

Several methodological limitations should be considered. The report describes only one patient, without a comparison group or statistical analysis, making it impossible to establish causality or estimate the incidence of this complication. The proposed relationship between chronic mechanical irritation, peri-implantitis, and squamous cell carcinoma remains speculative and is based on the chronological clinical course together with histopathological and material analyses.

Regarding research transparency, the authors state that they have no competing interests. No external funding was reported, and informed patient consent for publication was obtained, in accordance with the ethical statements included in the article.

9. Key Study Highlights

• Study design: Case report.
• Level of evidence: Low.
• Study population: One patient with squamous cell carcinoma developing around a maxillary subperiosteal implant.
• Number of patients: 1.
• Follow-up: The implant had been in function for approximately 20 years before diagnosis. The postoperative follow-up duration is not specified in the article.
• Primary outcome: Clinical and pathological assessment of a rare squamous cell carcinoma associated with long-standing subperiosteal implant complications.
• Main finding: The authors suggest that chronic mechanical irritation caused by implant mobility together with prolonged peri-implantitis may have contributed to persistent inflammation associated with this malignancy, whereas titanium deposition was not detected within the resected tissues.
• Scientific conclusion: Persistent peri-implant lesions associated with exposed subperiosteal implants should be carefully investigated, and malignancy should be considered in the differential diagnosis of atypical chronic lesions.
• Main limitations: Single-patient report, absence of control group, inability to establish causality, and limited generalizability.

10. Scientific Impact

This report makes a meaningful contribution to the implant dentistry literature by documenting what the authors describe as the first reported case of squamous cell carcinoma arising adjacent to a maxillary subperiosteal implant. Although exceptionally rare, the case expands current knowledge regarding the spectrum of long-term biological complications that may occur around historical implant systems.

Beyond its descriptive value, the publication encourages clinicians and researchers to consider the complex interaction between chronic mechanical trauma and persistent peri-implant inflammation. The complementary histopathological evaluation, implant surface analysis, and elemental characterization strengthen the biological discussion presented by the authors, while also suggesting that inflammatory mechanisms may be more relevant than titanium release in this individual case. These findings should not be extrapolated beyond the context of this single observation.

From a research perspective, the report highlights the need for additional investigations into long-term outcomes of aging subperiosteal implants and the biological consequences of chronic implant instability. Larger observational studies will be required to determine whether the associations proposed in this case can be confirmed in broader patient populations.

11. Editorial Conclusion

This case report describes an exceptionally rare presentation of oral squamous cell carcinoma developing around a long-standing maxillary subperiosteal implant in the presence of chronic implant mobility and persistent peri-implantitis. While the study does not establish a causal relationship, it underscores the importance of long-term clinical surveillance, meticulous maintenance, and careful assessment of chronic peri-implant lesions. For implant dentists and oral surgeons, the report serves as a reminder that persistent or atypical peri-implant soft tissue changes should be investigated thoroughly, including biopsy when clinically indicated, to ensure timely diagnosis of potentially serious pathology.