Influence of Ionizing Radiation on Fluoride-Releasing Dental Restorative Materials

Abstract

This study aimed to investigate the effects of radiotherapy on the mechanical, chemical, and surface properties of two recently introduced restorative dental materials (a glass hybrid and an alkasite), while two conventional restorative materials served as references. Material specimens of the experimental groups (irradiated) were compared to the specimens of the control groups that underwent the same preparation procedure but without irradiation. The experimental groups of restorative material specimens were irradiated with a total of 70 Gy over 35 days (2 Gy/day × 35 days), while the control groups received no treatment. The following properties were evaluated: surface microhardness (Vickers), surface roughness, color change, flexural strength, flexural modulus, material reliability, and infrared spectra. For the experimental groups, measurements were performed 24 h after specimen preparation, i.e., before radiotherapy and after the completion of the irradiation protocol. For the control groups, measurements were performed after the corresponding periods of no treatment. A statistically significant increase in microhardness (p = 0.001–0.004) and surface roughness (p = 0.013) was observed as a result of material aging/maturation in both the control and experimental groups. However, the only statistically significant difference between the control and experimental groups was observed in the discoloration of the conventional reference material (p < 0.001). In conclusion, no statistically significant negative effects of a therapeutic dose of radiotherapy on any of the tested properties of the alkasite and glass hybrid materials were observed, whereas only a minor negative effect of radiotherapy in terms of discoloration was found for a conventional resin composite that was used as a reference material.

Surface Roughness and Color Change of Gamma Irradiated Nanohybrid Resin Composite and Giomer Restorative Materials

“…For both materials, specimens in the control groups had signi cantly higher discoloration than irradiated specimens (p < 0.05). This was in partial agreement with Turjanski et al [29] who stated that all the materials tested showed some discoloration with aging. For resin composites, this is due to the post-reaction gradually changing the refractive index of the polymer, while a similar color change also takes place in glass ionomers during lengthy maturation [36] .…”

“…For both materials, color change measured after 6 months was signi cantly higher than 24 hours value (p < 0.05). This was in accordance with Turjanski et al [29] stated that Tetric EvoCeram showed higher discoloration in the irradiated group than the control group. In the comparisons among the materials, the highest values were observed for the glass-ionomer-based materials, compared to lower values found for the resin-based materials.…”

“…Results also revealed a non-statistically signi cant difference in roughness between control and gamma irradiated groups except for giomer 6 m groups in both tested materials. This agreed with Turjanski et al [29] who stated that there was no statistically signi cant difference between control and irradiated groups.…”

The damage and remineralization strategies of dental hard tissues following radiotherapy

“…The required sample size was determined using G*Power 3.1 software. Based on the findings from Turjanski et al [ 31 ], the sample size per group in the first experiment was 4 (20 samples total) with a probability higher than 80%, a statistically significant difference of at least 15%, and a 0.05 significance level. According to the research of Parisay et al [ 32 ], The resulting sample size in our second experiment was 10 per group with an effect size of 0.5, a power of 0.8, and a significance level of 0.05.…”