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.

Fluoride and Functionalised β-tricalcium Phosphate (fTCP) Fluoride Toothpaste Affect the Primary Dentin Caries Surface: A Comparison by Estimation Statistics

ABSTRACT@#This study aims to compare the effect of fTCP-contained toothpaste in combination with 950 ppm fluoride on primary dentin caries surface to ordinary 1100 ppm fluoride toothpaste by using estimation statistics. Dental caries with deep lesion and dentin exposure from nine primary teeth were cut into two equal parts and randomly divided into two groups in a before-after study. Each group was brushed with one type of toothpaste two times per day for 28 days and rested in artificial saliva. SEM images of cavity bottom surfaces and energy-dispersive X-ray spectrometry (EDX) were used to determine the percentage of calcium (Ca), phosphorus (P), fluoride (F) and oxygen (O) at six continuous measured areas from the surface of the cavity bottom into 45 µm depth before and after brushing. About 95% confidence interval of the mean difference was calculated by performing bootstrap resampling with 5000 resamples followed by comparison analysis. The percentage of Ca, P, F, O was shifted after treatment. There was no difference between the two groups. The SEM images reflected a similar illustration of EDX data. The combination of fTCP and 950 ppm fluoride in toothpaste showed equivalent effectiveness to the 1100 ppm fluoride toothpaste in primary dentin caries.

Observation and analysis of microstructure of dentin caries lesions through 3D laser scanning microscope / 华西口腔医学杂志

<p><b>OBJECTIVE</b>Microstructural changes in dentin carious lesions were investigated using a 3D laser scanning microscope, which has a morphological theoretical foundation in the further study of clinical caries disease prevention and treatments.</p><p><b>METHODS</b>Six fresh extracted caries molars were prepared into cross-section specimens. The sections were examined by 3D and laser measuring morphology.</p><p><b>RESULTS</b>Zones were identified in the lesions on the basis of their optical appearance. Two zones were identified in the lesions on the basis of their laser appearance. The microstructure showed that the tubular was partly closed in transparent dentin; peritubular and intertubular dentin were reduced in the zone of demineralization; peritubular and intertubular dentin were damaged and fused; a beaded sample and oval lesions formed in the zone of bacterial invasion; and abnormal dentin structure was present in the zone of destruction on the basis of their laser appearance. Four zones were iden-tified in the lesions according to their colors, as determined from their 3D appearance.</p><p><b>CONCLUSIONS</b>3D laser scanning micros-cope may be a powerful, accessible, and non-destructive technique, as it identified the lesion and tubular zones, as well as peritubular and intertubular dentin in the four zones' lesions. The microstructure of dentin caries lesions may have significant merit in the evaluation of clinical prevention and treatment.</p>