Impact of gamma radiation on marginal adaptation of nanohybrid composite and composition of dental hard tissues – Scanning electron microscopy and X-ray diffraction analysis: An in vitro pilot study.

Aims: This pilot study aimed to compare the marginal adaptation of composite resin at the tooth-restoration interface, before and after radiation. Subjects and Methods: Fifteen extracted premolars were divided into 2 experimental groups (based on the timing of irradiation) and 1 control group of 5 teeth each. In Group I (control group), teeth were restored but not exposed to radiation at any stage, Group II: teeth were irradiated before cavity preparation and restoration, and Group III: after cavity preparation and restoration employing selective etch technique, teeth were exposed to radiation. The samples were then sectioned buccolingually to analyze the extent of the marginal gap under scanning electron microscopy and compositional alteration of dental hard tissues by X-ray diffraction study. The data collected were analyzed statistically. Statistical Analysis Used: The statistical software used was IBM SPSS version 23 New York, USA, and analysis was done using two-way ANOVA followed by Turkey's post hoc test, this difference in the mean marginal gap between all three groups was nonsignificant (P ≥ 0.05). Results: In the control group (Group I), a minimum gap (4.203 µm ± 0.533) was observed at the tooth-restoration interface, indicating the highest level of adaptation as compared to Group II (5.816 µm ± 0.762) and Group III (4.862 µm ± 1.018). This suggests that radiation adversely affected the bonding between composite materials and both enamel and dentin, attributed to the alterations induced by radiotherapy in the chemical, physical, and morphological properties of both tooth structure and composite resin. Conclusions: Ionizing radiations adversely affect the bonding between enamel, dentin, and composite resin. Hence, restorative procedures should be performed before undergoing radiotherapy. [ABSTRACT FROM AUTHOR]