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Bone Reports Dec 2022The differences in bone nanomechanical properties between cortical (Ct) and trabecular (Tb) bone remain uncertain, whereas knowing the respective contribution of each...
The differences in bone nanomechanical properties between cortical (Ct) and trabecular (Tb) bone remain uncertain, whereas knowing the respective contribution of each compartment is critical to understand the origin of bone strength. Our purpose was to compare bone mechanical and intrinsic properties of Ct and Tb compartments, at the bone structural unit (BSU) level, in iliac bone taken from a homogeneous untreated human population. Among 60 PMMA-embedded transiliac bone biopsies from untreated postmenopausal osteoporotic women (64 ± 7 year-old), >2000 BSUs were analysed by nanoindentation in physiological wet conditions [indentation modulus (elasticity), hardness, dissipated energy], by Fourier transform infrared (FTIRM) and Raman microspectroscopy (mineral and organic characteristics), and by X-ray microradiography (degree of mineralization of bone, DMB). BSUs were categorized based on tissue age, osteonal (Ost) and interstitial (Int) tissues location and bone compartments (Ct and Tb). Indentation modulus was higher in Ct than in Tb BSUs, both in Ost and Int. dissipated energy was higher in Ct than Tb, in Int BSUs. Hardness was not different between Ct and Tb BSUs. In Ost or Int BSUs, mineral maturity (conversion of non-apatitic into apatitic phosphates) was higher in Ct than in Tb, as well as for collagen maturity (Ost). Mineral content assessed as mineral/matrix (FTIRM and Raman) or as DMB, was lower in Ct than in Tb. Crystallinity (FTIRM) was similar in BSUs from Ct and Tb, and slightly lower in Ct than in Tb when measured by Raman, indicating that the crystal size/perfection was quite similar between Ct and Tb BSUs. The differences found between Ost and Int tissues were much higher than the difference found between Ct and Tb for all those bone material properties. Multiple regression analysis showed that Indentation modulus and dissipated energy were mainly explained by mineral maturity in Ct and by collagen maturity in Tb, and hardness by mineral content in both Ct and Tb. In conclusion, in untreated human iliac bone, Ct and Tb BSUs exhibit different characteristics. Ct BSUs have higher indentation modulus, dissipated energy (Int), mineral and organic maturities than Tb BSUs, without difference in hardness. Although those differences are relatively small compared to those found between Ost and Int BSUs, they may influence bone strength at macroscale.
PubMed: 36213624
DOI: 10.1016/j.bonr.2022.101623 -
Pathogens (Basel, Switzerland) Sep 2022Background: Secondary caries often result in a high failure rate of resin composite restoration. Herein, we studied the dodecylmethylaminoethyl methacrylate−modified...
Background: Secondary caries often result in a high failure rate of resin composite restoration. Herein, we studied the dodecylmethylaminoethyl methacrylate−modified resin adhesive (DMAEM@RA) to investigate its pH-responsive antimicrobial effect on Streptococcus mutans and Candida albicans dual-species biofilms and on secondary caries. Methods: Firstly, the pH-responsive antimicrobial experiments including colony-forming units, scanning electron microscopy and exopoly-saccharide staining were measured. Secondly, lactic acid measurement and transverse microradiography analysis were performed to determine the preventive effect of DMAEM@RA on secondary caries. Lastly, quantitative real-time PCR was applied to investigate the antimicrobial effect of DMAEM@RA on cariogenic virulence genes. Results: DMAEM@RA significantly inhibited the growth, EPS, and acid production of Streptococcus mutans and Candida albicans dual-species biofilms under acidic environments (p < 0.05). Moreover, at pH 5 and 5.5, DMAEM@RA remarkably decreased the mineral loss and lesion depth of tooth hard tissue (p < 0.05) and down-regulated the expression of cariogenic genes, virulence-associated genes, and pH-regulated genes of dual-species biofilms (p < 0.05). Conclusions: DMAEM@RA played an antibiofilm role on Streptococcus mutans and Candida albicans dual-species biofilms, prevented the demineralization process, and attenuated cariogenic virulence in a pH-dependent manner.
PubMed: 36145446
DOI: 10.3390/pathogens11091014 -
Scientific Reports Jun 2022Assessment of enamel subsurface lesion remineralisation is essential for the evaluation of novel remineralisation technologies. The gold standard to assess subsurface...
Assessment of enamel subsurface lesion remineralisation is essential for the evaluation of novel remineralisation technologies. The gold standard to assess subsurface mineral gain of enamel lesions is transverse microradiography (TMR). However, some studies have utilised surface microhardness (SMH) to evaluate efficacy of remineralisation agents. The aim of this study was to assess remineralisation of enamel subsurface lesions using TMR and SMH after in vitro treatment with calcium-containing technologies, and to test correlation between the TMR and SMH measurements. The parameters obtained from the TMR and SMH analyses of enamel subsurface remineralisation were not significantly correlated. Furthermore, the enamel subsurface remineralisation as measured by TMR was significantly correlated with the water-soluble calcium concentration of the remineralisation products. Scanning electron microscopy revealed surface precipitates formed by specific remineralisation treatments obfuscated accurate assessment of remineralisation by SMH. It was concluded that TMR is a more appropriate method for analysis of enamel subsurface remineralisation, and that SMH values of remineralised enamel should be interpreted with caution. Using TMR the level of remineralisation (%R) by the different technologies was CPP-ACP/F (31.3 ± 1.4%); CPP-ACP (24.2 ± 1.4%); CaSO/KHPO/F (21.3 ± 1.4%); f-TCP/F (20.9 ± 1.0%); Nano-HA/F (16.3 ± 0.3%); Nano-HA (15.3 ± 0.6%) and F alone control (15.4 ± 1.3%).
Topics: Calcium; Calcium, Dietary; Cariostatic Agents; Microradiography; Minerals; Tooth Remineralization
PubMed: 35701508
DOI: 10.1038/s41598-022-13905-8 -
Journal of Applied Oral Science :... 2022The aim of this study is to test, in vitro, the anti-cariogenic effect of experimental hybrid coatings, with nano clays of halloysite or bentonite, loaded with sodium...
OBJECTIVE
The aim of this study is to test, in vitro, the anti-cariogenic effect of experimental hybrid coatings, with nano clays of halloysite or bentonite, loaded with sodium fluoride or with a combination of sodium fluoride and stannous chloride, respectively.
METHODOLOGY
The varnish Fluor Protector (1,000 ppm of F-) was used as positive control and no treatment was the negative control. Enamel specimens (5 mm × 5 mm) were obtained from bovine teeth. The specimens (n=10) had their surfaces divided into two halves (5 mm × 2.5 mm each), in which one half received one of the treatments (Hybrid; Hybrid + NaF; Hybrid + NaF + SnCl2; Hybrid + NaF Loaded; Hybrid + NaF + SnCl2 Loaded). The specimens were submitted to a cariogenic challenge using a biofilm model (S. mutans UA159, for 5 days). Enamel surfaces both under and adjacent to the treated area were analyzed for mineral loss and lesion depth, by transverse microradiography. The pH of the medium was measured twice a day, and the fluoride release was analyzed. Additional specimens were submitted to confocal analysis.
RESULTS
Data were statistically analyzed by two-way ANOVA followed by Tukey test (α=0.05). None of hybrid groups were able to reduce the lesion depth; the Hybrid + NaF group, however, was able to reduce mineral loss differing from the negative control (p=0.008). The groups showed no significant difference in the pH measurement and fluoride release. Confocal analysis confirmed that for all groups the biofilm growth was similar.
CONCLUSION
None of the hybrid groups reduced lesion depth, but the Hybrid + NaF group was able to promote protection against mineral loss.
Topics: Animals; Cariostatic Agents; Cattle; Dental Enamel; Fluorides; Minerals; Sodium Fluoride; Tin Compounds; Tooth Erosion
PubMed: 35507984
DOI: 10.1590/1678-7757-2021-0643 -
Dental Materials Journal Jul 2022The aim of this study was to investigate the mineral-promoting effects of in-office bleaching agent on enamel subsurface lesions. Enamel subsurface lesions were divided...
The aim of this study was to investigate the mineral-promoting effects of in-office bleaching agent on enamel subsurface lesions. Enamel subsurface lesions were divided into following groups; D: demineralized samples without any further treatment, DS: samples were further immersed in fresh saliva, DSR: samples were immersed in saliva followed by remineralization buffer, and DSBR: samples were immersed in saliva, subjected to in-office bleaching, and then immersed in remineralization buffer. The control group (CONT) consisted of untreated enamel specimens. Transverse microradiography showed that integrated mineral loss was significantly lower in the DSBR group than in the DSR group. Confocal laser Raman analysis revealed that ν1 phosphate peak height of 959 cm and mineral to matrix ratio of peak heights 959 cm to 1,610 cm in the DSBR group were similar to those in the CONT. In-office bleaching can promote enamel remineralization by altering or removing proteins infiltrated to enamel subsurface lesions.
Topics: Dental Enamel; Microradiography; Minerals; Phosphates; Tooth Remineralization
PubMed: 35491105
DOI: 10.4012/dmj.2021-229 -
Journal of Fish Diseases Aug 2022
Topics: Animals; Fish Diseases; Microradiography; Perciformes; Sea Bream
PubMed: 35397143
DOI: 10.1111/jfd.13622 -
Journal of Applied Oral Science :... 2022The initial characteristics of white spot lesion (WSLs), such as the degree of integrated mineral loss (ΔZ), depth and pattern of mineral distribution, have an impact...
UNLABELLED
The initial characteristics of white spot lesion (WSLs), such as the degree of integrated mineral loss (ΔZ), depth and pattern of mineral distribution, have an impact on further demineralization and remineralization. However, these lesion parameters have not been evaluated in WSLs produced from microcosm biofilms.
OBJECTIVE
This study characterized artificial white spot lesions produced on human enamel under microcosm biofilm for different experimental periods.
METHODOLOGY
In total, 100 human enamel specimens (4x4mm) were assigned to 5 distinct groups (n=20/group) differing according to the period of biofilm formation (2, 4, 6, 8 or 10 days). Microcosm biofilm was produced on the specimens from a mixture of human and McBain saliva at the first 8h. Enamel samples were then exposed to McBain saliva containing 0.2% sucrose. WSLs formed were characterized by quantitative light-induced fluorescence (QLF) and transverse microradiography (TMR). Data were analyzed by ANOVA/Tukey or Kruskal-Wallis/Dunn tests (p<0.05).
RESULTS
A clear time-response pattern was observed for both analyses, but TMR was able to better discriminate among the lesions. Regarding QLF analysis, median (95%CI; %) changes in fluorescence ∆Z were -7.74(-7.74:-6.45)a, -8.52(-8.75:-8.00)ab, -9.17(-10.00:-8.71)bc, -9.58(-10.53:-8.99)bc and -10.01(-11.44:-9.72)c for 2, 4, 6, 8, and 10 days, respectively. For TMR, median (95%CI; vol%.µm) ∆Z were 1410(1299-1479)a, 2420(2327-2604)ab, 2775(2573-2899)bc, 3305(3192-3406)cd and 4330(3972-4465)d, whereas mean (SD; µm) lesion depth were 53.7(12.3)a, 71.4(12.0)a, 103.8(24.8)b, 130.5(27.2)bc, 167.2(39.3)c for 2, 4, 6, 8 and 10 days, respectively.
CONCLUSION
The progression of WSLs formed on human enamel under microcosm biofilm can be characterized over 2-10 days, both by QLF and TMR analyses, although the latter provides better discrimination among the lesions.
Topics: Biofilms; Dental Caries; Dental Enamel; Humans; Microradiography; Saliva; Tooth Demineralization; Tooth Remineralization
PubMed: 35384988
DOI: 10.1590/1678-7757-2021-0560 -
Sichuan Da Xue Xue Bao. Yi Xue Ban =... Mar 2022To study the effect of the gene of TetR family on the acid production ability of ( ) and the bacteria's ability to induce tooth demineralization
OBJECTIVE
To study the effect of the gene of TetR family on the acid production ability of ( ) and the bacteria's ability to induce tooth demineralization
METHODS
The growth of two strains of UA159, Δ , the gene in-frame deletion strain, and Δ /pDL278- , the complement strain, was examined. The structure of biofilm was observed by laser scanning confocal microscopy (LSCM). The quantitative determination of water-insoluble extracellular polysaccharide (EPS) in the bacterial biofilms was done by anthrone-sulfuric acid method. The acid production capacity of was measured by glycolytic pH drop. The demineralization-inducing ability of the strains on bovine teeth was determined by transverse microradiography (TMR).
RESULTS
The growth curves of the strains showed that did not affect the growth of . According to the findings of LSCM observation, did not affect the biofilm formation. According to the findings of the anthrone-sulfuric acid method, did not have any significant impact on the EPS synthesis of . The results of the glycolytic pH drop assay showed that the deletion of delayed the rate of acid production by when sucrose was the only carbon source. In addition, according to the TMR results, knocking out reduced the depth and amount of demineralization induced by on the surface of bovine teeth.
CONCLUSION
The deletion of can weaken the acid production ability and the demineralization ability of .
Topics: Animals; Biofilms; Cattle; Streptococcus mutans
PubMed: 35332727
DOI: 10.12182/20220360104 -
Antibiotics (Basel, Switzerland) Mar 2022This study investigated the effects of herbal toothpaste on bacterial counts and enamel demineralization. Thirty-six bovine enamel samples were exposed to a microcosm...
This study investigated the effects of herbal toothpaste on bacterial counts and enamel demineralization. Thirty-six bovine enamel samples were exposed to a microcosm biofilm using human saliva and McBain saliva (0.2% sucrose) for 5 days at 37 °C and first incubated anaerobically, then aerobically-capnophilically. The following experimental toothpaste slurries (2 × 2 min/day) were applied: (1) (10 mg/g); (2) (5 mg/g); (3) (80 mg/g); (4) Myrrha and propolis toothpaste (commercial); (5) fluoride (F) and triclosan (1450 ppm F), 0.3% triclosan and sorbitol (Colgate, positive control); (6) placebo (negative control). The pH of the medium was measured, bacteria were analyzed using quantitative polymerase chain reaction, and enamel demineralization was quantified using transverse microradiography. The total bacterial count was reduced by toothpaste containing , , fluoride, and triclosan (commercial) compared to the placebo. As far as assessable, , , and Myrrha and propolis (commercial) inhibited the outgrowth of , while spp. were reduced/eliminated by all toothpastes except . Mineral loss and lesion depth were significantly reduced by all toothpastes (total: 1423.6 ± 115.2 vol% × μm; 57.3 ± 9.8 μm) compared to the placebo (2420.0 ± 626.0 vol% × μm; 108.9 ± 21.17 μm). Herbal toothpastes were able to reduce enamel demineralization.
PubMed: 35326877
DOI: 10.3390/antibiotics11030414 -
Journal of Applied Oral Science :... 2022Quantification of collagen degradation is an important parameter to evaluate dentin caries for preventive aid.. Evaluate preventive methods against root collagen...
OBJECTIVES
Quantification of collagen degradation is an important parameter to evaluate dentin caries for preventive aid.. Evaluate preventive methods against root collagen degradation by the hydroxyproline assay (HYP) and microradiography technique (MRT).
METHODOLOGY
Five bovine root dentin blocks were obtained and subjected to an artificial demineralization process by acetate buffer (pH 5) to induce carious lesion formation. Samples were subjected to the following therapeutic treatments: 1) 0.12% chlorhexidine for 1 min, 2) 2% fluoride for 1 min, 3) Nd:YAG Laser (400 μm diameter optical fiber, 10 Hz frequency, 60 mJ/pulse energy, 48 J/cm2 energy density, in noncontact mode for 10 s), 4) deionized water (control) for 1 min, 5) MRT control group (without treatment and removal of collagen). Samples were exposed to degradation by a collagenase enzyme for five days. The enzyme solution was collected, by colorimetry in a spectrophotometer, from the collagen matrix for the hydroxyproline release analysis. The same samples were subjected to an additional two days of demineralization to induce the progression of mineral loss. Samples were analyzed by MRT for the visualization of their degraded areas (estimation of lesion depth and mineral loss). ANOVA was applied to compare hydroxyproline release rates. MRT data were subjected to the Kruskal-Wallis test, followed by the Dunn's test. Comparisons between the initial five-day and the subsequent two-day demineralization processes were performed by repeated t-test or Wilcoxon (p<0.05) measurements.
RESULTS
The amount of HYP released from the dentin samples failed to show significant differences among the groups (p=0.09). Fluoride and chlorhexidine were able to interact with the samples, reducing the progression of dentin caries after removal of the demineralized organic matrix. CHX was the only treatment able to show significant lower lesion depth than the negative control.
CONCLUSION
Chlorhexidine and fluoride were effective in reducing root caries progression.
Topics: Animals; Cattle; Chlorhexidine; Dentin; Fluorides; Root Caries; Tooth Demineralization
PubMed: 35293423
DOI: 10.1590/1678-7757-2021-0496