Abstract: BACKGROUND: Resin infiltration is an effective way to repair the initial caries of enamel, but recent studies have found that it has defects such as insufficient anti-mineralization ability, aggregation shrinkage, easy aging and poor color stability. 
OBJECTIVE: To observe the restoration effect and stability of resin infiltration combined with bioactive glass on demineralized tooth enamel. 
METHODS: 100 isolated human tooth specimens were selected to establish an artificial enamel demineralization model, which were randomly divided into four groups and received remineralization treatment. In the group A, models were immersed in artificial saliva. In the group B, the models were immersed in artificial saliva after resin infiltration treatment. In the group C, the models were treated with resin infiltration and then treated with sodium fluoride (twice a day), and finally immersed in artificial saliva. In the group D, the models were treated with resin infiltration and treated with bioactive glass (twice a day), and finally immersed in artificial saliva. The remineralization time of the four groups was 4 weeks. After remineralization, the four groups were re-demineralized and removed after 72 hours. Optical coherence tomography, enamel surface roughness and enamel microhardness were measured before treatment, after demineralization, after remineralization and after re-demineralization. 
RESULTS AND CONCLUSION: (1) Optical coherence tomography scan showed that the enamel surface of each group was smooth before treatment; the signal was strongest; and there was no difference between the groups. After the initial demineralization, the surface of each group was slightly uneven; the signal enhancement region extended below the surface; and there was no difference between the groups. After remineralization and re-demineralization, the signal enhancement region extended more obviously below the surface, and the signal enhancement region of group D enamel surface was weakened more significantly than other groups. (2) Before treatment and after initial demineralization, there was no significant difference in enamel surface roughness between four groups (P > 0.05). After remineralization, the roughness values were: group A > group B > group C > group D, and the difference was significant among groups (P < 0.01). After re-demineralization, the roughness value of group A was higher than that after the initial demineralization (P < 0.01); the roughness values of groups B, C, and D were lower than those after the initial demineralization (P < 0.01). (3) Compared with the initial demineralization, there was no significant difference in microhardness between the four groups (P ﹥ 0.05). After remineralization, the microhardness values were: group A < group B < group C < group D, and the difference was significant among groups (P < 0.01). After re-demineralization, the microhardness value of group A was lower than that after the initial demineralization (P < 0.01); the microhardness values of groups B, C, and D were higher than those after the initial demineralization (P < 0.01). (4) The results showed that the effect and anti-demineralization stability of porous resin combined with bioactive glass were better than that of using only permeable resin combined with fluoride.

Key words: material, resin infiltration, bioactive glass, remineralization, re-demineralization, surface roughness, microhardness