SDF Effective Management of Radiation Caries: an in Vitro Study

Objectives: For oncologic patients undergoing head and neck radiotherapy (HNRT), the rapid and chronic progression of radiation-related caries (RRCs) signifies an abrupt deterioration in oral health. This study investigated the effectiveness of SDF at arresting carious lesions in irradiated teeth, and compared to alternative preventive topical fluoride applications currently being implemented.
Methods: Randomly assigned tooth samples were subjected to in vitro irradiation comparable to typical HNRT treatment protocols, followed by a series of controlled chemical pH cycling to mimic artificial lesions. Experimental groups (N = 15) comprised of: controls (N = 10); SDF; and nano medical hydroxyapatite remineralization paste with topical neutral fluoride gel (mHAP+F).
Results: Baseline ATR-FTIR identified characteristic HAp functional groups: hydroxyl; carbonate; and phosphate. Post pH cycling suggested water removal and relative CO₃^2- and PO₄^3- loss. It was clear from gradual increased Ca:P ratios group SDF altered enamel microstructure simply with application; FAp formation at 10 and 100nm, with CaF₂ at 30nm. While group mHAP+F, which inundated the surface with Ca²⁺ at baseline, remained unchanged, alternatively increasing FAp formation across profile depths. Interestingly, SEM images of both SDF and mHAP+F demonstrated restoration of surface destruction associated with irradiated and demineralized enamel; restoration remained evident post pH cycling. EDX spectra confirmed large, bright clusters of variously sized Ag precipitates on the surface of group SDF. Additional analysis verified At.%F after mHAP+F application. 3-way ANOVA comparison showed significant interaction of At.%Ag and O between group and with condition (<0.0001). Mechanical properties were investigated with Vickers hardness, demonstrating both SDF and mHAP+F significantly increased surface hardness. However, when comparing between groups, there was no significant difference. Findings of micro-CT indicated no difference in Relative Enamel Density.
Conclusions: SDF has equal [in vitro] benefit at prevention and arresting RRCs as the current mHAP+F treatment protocol for clinical management of RRCs.. This research provides evidence for the recommendation of further investigations and basis for future clinical studies.