Dental implant-associated oral squamous cell carcinoma: a clinical retrospective study of 22 cases

In oral cavity, oral squamous cell carcinoma (OSCC) is the most common malignant neoplasm. Established risk factors for OSCC include tobacco use, genetic predisposition, viral infections, and poor oral hygiene. With the increasing prevalence of dental implant (DI) procedures, reports of OSCC developing around implants have also risen. This study aims to investigate potential risk factors and clinical characteristics of OSCC occurring in association with dental implants, in order to improve understanding of its etiology and prognosis.

This retrospective study analyzed the medical records of 22 patients diagnosed with OSCC around dental implants at the Department of Oral and Maxillofacial Surgery at a single institution, between 2009 and 2024 by a single surgeon. All patients presented with persistent discomfort or abnormal lesions following implant placement and were subsequently diagnosed with OSCC via histopathological examination. Pre-treatment imaging included magnetic resonance imaging, contrast-enhanced computed tomography, PET/CT, and bone scans. The 8th edition of the American Joint Committee on Cancer (AJCC) guidelines was used to determine cancer staging. Data were collected on patient demographics, smoking and alcohol histories, implant placement date, and histopathologic findings through electronic medical records.

All 22 patients presented with inflammatory lesions or progressive bone loss around dental implants. Five patients had a history of malignancy in other organs or hematologic disease. Six male patients had habitual alcohol consumption and smoking. OSCC occurred predominantly in the mandible (77.3%), with 95.5% of tumors classified as T4 at diagnosis. Neck metastasis developed in 41% of patients (9/22), including four cases of delayed/occult nodal involvement. The mean interval from implant placement to OSCC diagnosis was 4.7 years, with nearly half diagnosed within 1 year. Histopathology revealed only well- or moderately differentiated tumors, with bone invasion present in 95.5% of cases. The mean depth of invasion was 13.2 mm. Twenty patients underwent surgical resection, while two received nonsurgical treatment due to systemic condition. The mean survival time was 25.7 months, and Kaplan-Meier analysis showed no significant survival difference between maxillary and mandibular OSCC.

OSCC after dental implant placement, though uncommon, is a significant clinical issue due to its late diagnosis, aggressive bone invasion, and poor prognosis. Our findings underscore the importance of differentiating OSCC from peri-implantitis and recommend prompt biopsy when peri-implant inflammation persists despite conventional treatment. Early recognition may improve survival outcomes. The observed links with prior malignancy, chronic inflammation, and lifestyle risk factors suggest a multifactorial etiology, highlighting the need for further longitudinal studies to refine prevention and early detection strategies.