Influence Of Radiation Therapy On The Hard Tissue Of Deciduous Teeth And Prevention Of Different Remineralization Agents

Background The effect of radiotherapy on the permanent teeth had been reported by some researchers. It is due to the change of oral environment, bacterial flora and saliva composition of head and neck cancer patients, moreover the direct atomic radiation for teeth, eventually forming a radioactive decay. Researches about effects of radiation on the teeth are usually the change of physical and mechanical properties. Radiotherapy can change the hard tissue structure, with the micro-hardness reducing and microscopic structure irregular, which so as to make the tooth structure in a weak state. Once, caries condition appeared or gradually serious, the teeth may happen to be demineralization and dental caries, immediately. In recent years, due to the incidence of children head neck malignant tumor has a tendency to increase gradually, the influence of atomic irradiation on children is brought to the attention of medical workers and researchers. For children, because of the characteristic of age, immature intelligence, poor ability and compliance, it is hard to conduct and complete daily oral hygiene. Moreover, comestible of children are mainly sweet food, processed diet, which added to more difficulties to maintain the oral hygiene, along with the irregular intake time. Therefore, the risk of decay is high.Taking some protective measures on teeth before and after radiotherapy is the most important problem for the patients itself and clinical doctors. Remineralization agents are the most effective materials to prevent demineralization. The most commonly used materials before and after are fluoride, CPP-ACP, CPP-ACPF in clinical to protect teeth. However, for CPP-ACP, CPP-ACPF are less in. Some literatures are reported that radiation direct damage is related or similar to demineralization. The method to prevent caries is mainly about local fluoride, however for CPP-ACP, CPP-ACPF is less in China. Therefore, the aim of this study is to explore the effect of radiotherapy on the deciduous teeth and to find a most effective method to prevent decay before and after radiotherapy in different Remineralization agents. And then healthy teeth can maintain the denture structure integrity and keep function well.Objectives To explore the influence of radiotherapy on the hard tissue of deciduous teeth. By comparing the effect of three different remineralization agents on the micro-hardness and micro-structure of deciduous teeth, and then finding a most effective method to protect childhood teeth before and after radiotherapy.Materials and Methods 1. Forty healthy and freshly extracted or freshly exfoliated human deciduous molar teeth were mesiodistally sectioned, yielding 2 buccal and lingual hemisections, and forty vestibular sections were randomly subjected to enamel experiment. Following the principle of self-control, the enamel initial micro-hardness was evaluated prior to irradiation. The trial halves were irradiated fractionally up to 40 Gy, 2Gy/day, 1time/day, 5 times/week,4 weeks totally. The enamel micro-hardness was evaluated after each 10 Gy irradiation,and then the micro-hardness of deciduous teeth was observed by micro-hardness testing and the microscopic morphology changes scanning electron microscopy(SEM) after all exposure.2. Seventy deciduous teeth were chosen for this study and randomly divided into two experiments, micro-hardness test and scanning electron microscope test. Each of experiment is divided into 5 groups: 1) blank(no irradiation), 2) irradiation(40 Gy) control group, 3) application of fluoride plus irradiation, 4) application of CPP-ACP plus irradiation, and 5) application of CPP-ACPF plus irradiation. The tested agents were applied on the teeth according to the manufacturer’s recommendations. The surface micro-hardness of samples before and after treatment was measured by a micro-hardness tester. Morphological changes of the enamel surface were examined by the scanning electron microscope(SEM).Results 1. The microhardness of deciduous teeth enamel decreases with increasing radiation dose. The SEM displayed that a significant change in the enamel surface in contrast with all of the analyzed regions of non-irradiated enamel, With increasing doses of irradiation, a progressive change was also observed on the surface morphology, appearing amorphous appearance.2. The enamel micro-hardness of deciduous teeth in the 40-Gy radiation control group was decreased compared with the blank group(p < 0.05). There was no difference between fluoride and CPP-ACP groups(both treated with radiation)(p > 0.05). The highest mean value of micro-hardness was found in the CPP-ACPF group with radiation. All groups exhibited inordinate changes and mineral deposit on their enamel surface by the SEM.Conclusions 1. The micro-hardness of hard tissue of deciduous teeth decreases with increasing radiation dose, a progressive disruptive change was also observed on the surface morphology.2.The enamel was severely affected by irradiation. The micro-hardness was decreased at a dose of 40 Gy and the micro-structure of enamel surface disrupted. All the agents tested in this in vitro study prevented the demineralization of irradiation and enhanced remineralization. The highest cariostatic effect was achieved by the CPP-ACPF treatment.