Effect of Casein Phosphopeptide-Amorphous Calcium Phosphate on the Microhardness and Fracture Resistance of...

Introduction Radiotherapy, one of the most important modalities of treating head and neck cancer, causes xerostomia, mucositis, and structural and chemical changes in dental hard tissues. These factors favour the commencement of radiation-induced caries. Aim The study aimed to evaluate the changes in enamel microhardness and fracture resistance after irradiation and the effect of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on the same. Materials and methods Fifty extracted human premolar teeth were debrided and cleansed using an ultrasonic scaler. In order to test for fracture resistance, 30 teeth were embedded in dental acrylic covering the entire root, leaving the crown exposed at the level of the cementoenamel junction (CEJ). For microhardness testing, 20 teeth were prepared by sectioning at the CEJ using a diamond disk with water. The crowns were sectioned longitudinally so as to keep the labial enamel, followed by mounting in acrylic resin. The samples were divided into the following groups: control, irradiation, and irradiation+CPP-ACP. The samples were subjected to irradiation for a total of 35 fractions equal to 70 Gy, with 2 Gy exposure per day applied five days per week, for seven weeks with X-rays from a linear accelerator (Elekta Infinity, Elekta AB, Stockholm, Sweden). In two groups, CPP-ACP (GC Tooth Mousse, GC Corporation, Tokyo, Japan) was applied onto the tooth surface using a microbrush and left for three minutes. The samples were tested for fracture resistance using a universal testing machine and surface microhardness using a microhardness tester. The data was analyzed using the Kruskal-Wallis test and Mann-Whitney U test. Results The mean microhardness of the control group was 323.50±7.76, the irradiation group was 269.60±9.41, and the irradiation and medicament group was 288.90±10.10. The mean fracture resistance of the control group was 1315.35±163.43, the irradiation group was 835.10±75.46, and the irradiation and medicament group was 1010.35±76.69. There was a significant difference between the groups for microhardness (a chi-squared value of 24.24 and a p-value of 0.001) and fracture resistance (a chi-squared value of 23.81 and a p-value of 0.001). Conclusion According to the findings of this study, we conclude that a radiation dose of 70 Gy alters microhardness and fracture resistance of enamel. The application of remineralizing agent CPP-ACP significantly improves the microhardness and fracture resistance of irradiated enamel. However, the application of CPP-ACP doesn't improve the microhardness and fracture resistance up to the level of a natural tooth.