Effects of novel bioactive glasses on promoting remineralization of artificial dentin caries / 北京大学学报(医学版)

OBJECTIVE@#To investigate the effects of novel bioactive glasses (BG) including PSC with high phosphorus component and FBG with fluorine-doped element on promoting remineralization of artificial dentin caries.@*METHODS@#(1) BGs were used in this study as follows: PSC (10.8%P2O5-54.2%SiO2-35.0%CaO, mol.%) were synthesized using phytic acid as the phosphorus precursor through sol-gel method. FBG (6.1%P2O5-37.0%SiO2-53.9%CaO-3.0%CaF2, mol.%) and 45S5(6.0%P2O5-45.0%SiO2-24.5%CaO-24.5%Na2O, mol.%) were synthesized by traditional melt method. (2) The above BGs were soaked in simulated body fluid (SBF) for 24 hours. Then X-ray diffraction (XRD) was used to analyze the formation of hydroxyapatite (HA) crystals. (3) Prepared 1 mm thick dentin slices were soaked in 17% ethylene diamine tetraacetic acid (EDTA) for 1 week to demineralize the dentin. Then the dentin slices treated by BG were soaked in SBF for 1 week. Field emission scanning electron micro-scopy (FE-SEM) was used to observe the surface morphology of the dentin slices. (4) Four cavities were prepared to 1 mm depth in each 2 mm thick dentin slice, then were treated with lactic acid for 2 weeks to form the artificial dentin caries. Wax, mineral trioxide aggregate (MTA), PSC and FBG were used to fill four cavities as blank control group, MTA group, PSC group and FBG group respectively. Then the spe-cimens were soaked in SBF for 4 weeks. The changes of depth and density of demineralized dentin were analyzed using Micro-CT before filling and after 2 and 4 weeks filling.@*RESULTS@#(1) PSC and FBG promoted mineral formation on the surfaces of the demineralized dentin. And the speed was faster and crystallinity was higher in PSC group than the FBG and 45S5 groups. (2) The increased mineral density of artificial dentin caries in PSC group were (185.98 ± 55.66) mg/cm3 and (213.64 ± 36.01) mg/cm3 2 and 4 weeks after filling respectively, which were significantly higher than the control group [(20.38 ± 7.55) mg/cm3, P=0.006; (36.46 ± 10.79) mg/cm3, P=0.001]. At meanwhile, PSC group was also higher than MTA group [(57.29 ± 10.09) mg/cm3; (111.02 ± 22.06) mg/cm3], and it had statistical difference (P=0.015; P=0.006). The depth of remineralized dentin in PSC group were (40.0 ± 16.9) μm and (54.5 ± 17.8) μm 2 and 4 weeks respectively, which were also statistically different from the control group (P =0.010;P=0.001). There were no statistical differences between the control group and MTA group. The above effects of FBG group were between PSC and MTA.@*CONCLUSION@#PSC has advantages in the speed, quality and depth of mineral deposition in the demineralized layer of artificial dentin caries. It would be expected to be an ideal material to promote the remineralization of dentin caries.

Physical and chemical properties of pulp capping materials based on bioactive glass / 北京大学学报(医学版)

OBJECTIVE@#To investigate the physical and chemical properties of pulp capping materials based on bioactive glass (BG).@*METHODS@#Novel BG pulp capping materials were composed of powder and fluid. The powder was BG (82.36% SiO2, 15.36% CaO, and 2.28% P2O5) synthesized by using the sol-gel method combined with template technology. Two kinds of fluid were provided: (1) phosphate buffer (PB) solution and (2) phosphate buffer solution with 1% sodium alginate (SA) addition. After mixing the powder and fluid, BG-PB and BG-PB-SA were prepared. Setting time and compressive strength of the BG pulp capping materials were tested by setting time loading system and mechanical testing machine. Statistical analysis was performed using the independent sample t-test, with the significance set at 0.05. pH meters was used to test the pH of the BG pulp capping materials and mineral trioxide aggregate (MTA). The sealing ability of the BG pulp capping materials and MTA was tested by methylene blue dye leakage model. Statistical analysis was performed using one-way ANOVA analysis and LSD multiple comparison, with the significance set at 0.05.@*RESULTS@#(1) Setting time: the initial and final setting time of BG-PB were (7.2±0.3) min and (12.7±0.9) min, respectively. And the initial and final setting time of BG-PB-SA was (7.5±0.3) min and (13.6±1.6) min. There was no significant difference between BG-PB and BG-PB-SA groups (P>0.05). (2) Compressive strength: the compressive strength of BG-PB was (16.5±1.8) MPa at 1 day and (14.1±3.7) MPa at the end of 28 days. However, the compressive strength of BG-PB-SA was (26.6±6.3) MPa on day 1 and (21.6±5.6) MPa on day 28, which was significantly higher than that of BG-PB (P<0.05). (3) pH: the pH of BG pulp capping materials' bulk immersed in simulated body fluid (SBF) went up to 8.06, and the highest pH of MTA was 8.47. Significant difference was observed between the BG pulp capping materials and MTA (P<0.05). (4) Sealing ability: the optical density (D) in positive control group was significantly higher than ln BG-PB, BG-PB-SA and MTA groups (P<0.05). And BG-PB and BG-PB-SA showed the similar favorable sealing ability with MTA, and no significant difference was observed among the three groups (P>0.05).@*CONCLUSION@#The novel BG pulp capping materials showed good physical properties, especially BG's setting time was short; BG pulp capping materials are promising.