Dosimetric impact of titanium, zirconia, and customized subperiosteal dental implants in head and neck radiotherapy: an in vitro study.

BACKGROUND

High-density dental implant materials may lead clinically relevant uncertainties in dose calculation and delivery during head and neck radiotherapy (RT). This study aimed to experimentally and computationally evaluate the dosimetric impact of titanium, zirconia, and customized subperiosteal implants.

MATERIAL AND

METHODS

Three implant types were positioned within artificial bone phantoms (Sawbones®) simulating a human mandible. For the subperiosteal group, a patient-specific framework was digitally designed and manufactured. Optically Stimulated Luminescence (OSL) dosimeters were placed at four anatomical locations (distal, buccal, mesial, and lingual) around each implant. Computed tomography (CT) scans (1-mm slice thickness) were obtained, and Intensity-Modulated Radiation Therapy (IMRT) plans were generated using a treatment planning system (TPS) equipped with the AcurosXB (AXB) algorithm with 6-MV photon energy and a target dose of 200 cGy. Statistical analysis was performed using the Wilcoxon Signed-Rank test on dependent groups to compare TPS-calculated and OSL-measured doses.

RESULTS

A significant discrepancy was found between the overall measured and planned doses (p=0.003), with a median dose deviation of -7.8%. Backscatter-induced dose enhancement was systematically detected in the buccal region (up to +1.9%), whereas dose attenuation was predominant in the lingual and mesial regions (up to -14.5%). TPS-calculated maximum point doses revealed substantial hot spots, reaching 228 cGy for zirconia and 217 cGy for subperiosteal implants at the over-the-implant interface. While significant differences were confirmed for the endosseous group (p=0.021), the customized subperiosteal group demonstrated a trend toward a more predictable dosimetric profile (p=0.068) with a lower median deviation (-6.8%) compared to both titanium (-7.8%) and zirconia (-10.5%) endosseous implants.

CONCLUSIONS

Dental implant material and design influence dose distribution during RT, with high-density materials such as zirconia associated with greater discrepancies in dose estimation. Customized subperiosteal implants demonstrated a more predictable dosimetric profile in this experimental setting; however, the clinical significance of these findings remains to be established through larger studies incorporating clinical outcome data.