Background: Radiotherapy is a key treatment for head and neck cancers but often compromises oral health, partly through its impact on restorative materials. A specific concern is whether ionizing radiation alters the water absorption and solubility of fluoride-releasing restoratives, potentially affecting their durability. This study aimed to evaluate these properties following clinically relevant radiation exposure. Methods: Seven contemporary fluoride-releasing restorative materials (Fuji IX, Equia Forte HT, Fuji Triage, Activa Presto, Cention, Luminos, and Beautifil II) were tested (n = 10 per group). Specimens were either irradiated with 70 Gy in 35 fractions using a clinical linear accelerator or maintained as non-irradiated controls. Water absorption and solubility were measured over 35 days according to ISO 4049 protocols, and data were analyzed with repeated-measures ANOVA. Results: Across all materials, irradiated specimens exhibited slightly higher water absorption and solubility values compared to controls; however, differences were not statistically significant (p > 0.05). Material-specific trends were observed, with Fuji IX, Fuji Triage, Beautifil II, and Equia Forte showing relatively higher absolute values. Conclusions: Clinically relevant ionizing radiation did not significantly affect the water absorption or solubility of the tested fluoride-releasing restorative materials, suggesting preserved physicochemical stability under therapeutic conditions.

To examine the effect of ionizing radiation on fluoride release from restorative dental materials, samples of Equia Forte HT, Fuji Triage, Fuji IX, Cention Forte, Activa Presto, Beautifil II, and Luminos (n = 10) were made in Teflon molds and divided into a control group and an experimental group. The experimental group was exposed to ionizing radiation for a total of 35 days (70 Gy, 2 Gy per day). The fluoride release was measured with a fluorine-selective electrode. The median recorded fluoride values were higher with Equia Forte HT, Fuji Triage, and Fuji IX compared to others during the entire period in both groups. With Activa Presto, a higher release of fluoride was recorded in the experimental group on the first day of irradiation, while a higher release was recorded in the control group, as well as with Luminos and Beautifil II. With Cention Forte, there was no significant difference in fluoride release between the experimental and control groups except on the sixth day. With Fuji Triage and Fuji IX, the release of fluoride was higher in the experimental group compared to the control group, while with Equia Forte HT, there was no difference between the groups. In conclusion, ionizing radiation has no major effect on fluoride release in all the tested materials.

Silver diamine fluoride/potassium iodide (SDF/KI) Riva Star (SDI) is a tooth desensitizing and anti-caries agent that may be indicated for arresting caries before restoring the tooth in selective caries approach. The aim was to determine the effect of SDF/KI pretreatment on the bonding of SDR Plus Bulk-Fill Flowable (Dentsply) with Clearfil SE Bond 2 (Kuraray) and G-Premio Bond (GC) in self-etch mode on sound dentin. A total of 240 dentin samples were prepared and assigned to 12 groups based on SDF/KI pretreatment (with or without), adhesive type, and testing time (1, 3, and 6 months). The shear bond strength (SBS) was measured using an UltraTester. SBS data were analyzed using three-way factorial model (Adhesive × Pretreatment × Time) and Wald (F) tests, with α = 0.05. Fracture modes were analyzed using χ² and Fisher’s exact test, with α = 0.05. Clearfil performed significantly better than G-Premio at all time points (p < 0.001). Riva Star pretreatment significantly reduced SBS for both adhesives at all time points (p < 0.001). SBS reduction was significantly higher for Clearfil (p < 0.001). The effect of storage was not significant (p = 0.388). Fracture mode distribution differed significantly between adhesives (p < 0.001). Pretreatment × fracture interaction was significant for Clearfil (p = 0.0052). Mixed fractures in G-premio were rare.