Conservative Retention of Pre-Existing Dental Implants Contralateral to Adjuvant Radiotherapy for Maxillary Oral Squamous Cell Carcinoma: A 4-Year Follow-Up Case Report.

Background: Dental implant survival after high-dose head-and-neck radiotherapy (RT) is uncertain, and whether to explant pre-existing implants before RT remains controversial. Case: A 58-year-old man with oral squamous cell carcinoma (OSCC) of the left hard palate involving the maxilla (pT4a pN2c M0) underwent left maxillectomy with bilateral neck dissection. Two right-sided contralateral maxillary implants and three mandibular implants were retained. Adjuvant RT was delivered using IMRT/IGRT to a total dose of 70 Gy in 35 fractions to the surgical bed. Outcome: During 4 years of follow-up with clinical examinations and panoramic radiographs, there was no clinical evidence of peri-implantitis, implant mobility, or radiographic evidence of progressive peri-implant bone loss around the retained implants. According to the RT treatment plan, the estimated radiation dose was 61.7 Gy at the contralateral maxillary implant sites and 29.2 Gy at the mandibular implant sites. The patient later developed an unrelated supraglottic squamous cell carcinoma treated with RT; the retained implants remained clinically stable. Conclusion: This case suggests that clinically healthy pre-existing implants may not require routine explantation before adjuvant RT, even when implant-site radiation exposure is substantial. Conservative retention should be accompanied by close clinical and radiographic surveillance.