Anti-inflammatory and Mineralization Effects of ProRoot MTA and Endocem MTA in Studies of Human and Rat Dental Pulps In Vitro and In Vivo

Introduction

Few studies have reported direct pulp capping in inflamed pulp conditions. The purpose of this study was to investigate the in vitro and in vivo responses of dental pulp during direct pulp capping using various pulp capping materials in inflamed conditions.

Viscoelastic properties of human cortical bone tissue depend on gender and elastic modulus

Bone exhibits rate‐dependent failure behavior, suggesting that viscoelasticity is a factor in the damage and fracture of bone. Microdamage initiates at scales below the macroscopic porosity in bone, and, as such, is affected by the intrinsic viscoelasticity of the bone tissue. The viscoelasticity of the bone tissue can be measured by nanoindentation and recording the creep behavior at constant load. The viscoelastic properties have been used to assess differences in tissue behavior with respect to fracture healing, aging, and mouse strains. In this study, we compared the viscoelastic behavior of human cortical bone between genders by using nanoindentation at a fixed load of 10 mN to measure the creep time constant. Bones from females had a significantly greater time constant, indicating slower creep and relaxation, than bones from males. The creep time constants decreased with increasing tissue modulus. The mineralization, collagen content, and collagen cross‐link density, which were bulk measurements, were analyzed to determine if the differences in viscoelastic behavior were explained by compositional differences in the bone. However, none of the parameters differed between genders, nor were they correlated to the viscoelastic time constant. As such, the difference must depend on other matrix proteins that we did not assess or differences in the microstructural organization. This is one of the only intrinsic bone material properties that has been found to differ between males and females, and it may be important for assessing differences in fracture risk, since crack propagation is generally sensitive to viscoelastic properties. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 30:693–699, 2012     

早产儿代谢性骨病临床管理专家共识（2021年）（英文翻译）

早产儿代谢性骨病（metabolic bone disease of prematurity,MBDP）是由于机体钙磷代谢紊乱导致骨矿物质含量减少的全身性骨骼疾病。我国目前对MBDP尚缺乏深入研究和系统认识,在临床管理方面存在很多不规范之处。现基于国内外相关研究,采用证据推荐分级的评估、制定与评价方法（Grading of Recommendations Assessment,Development and Evaluation）,制定MBDP临床管理专家共识,从MBDP的高危因素、筛查/诊断、预防、治疗及出院后随访等5个方面提出推荐意见,旨在为相关从业人员提供 MBDP临床管理的建议,以减少MBDP的发生及改善其近远期预后。     

Undercarboxylated osteocalcin and bone mass in 8–12 year old children with cystic fibrosis

Young adults with cystic fibrosis (CF) frequently develop bone disease. One suggested aetiological factor is suboptimal vitamin K status with impaired carboxylation of osteocalcin and abnormal bone formation. METHODS: We measured bone mineralization and turnover in thirty-two 8-12 year old CF patients (14 boys) using Dual Energy X-ray absorptiometry (whole body (WB) and lumbar spine (LS)), 25-OH Vitamin D, PTH and markers of bone formation (plasma osteocalcin, N-terminal pro-peptide of type 1 collagen (P1NP)), plus an indirect measure of vitamin K status, undercarboxylated osteocalcin (uc-OC). RESULTS: LS bone mineral density (BMD) standard deviation (SD) scores were < -1.0 in 20% of subjects. Size-adjusted LS and WB bone mass was normal. Compared to reference data, % uc-OC was high and P1NP low. LS bone mass was predicted by % uc-OC but not other markers (0.4% decrease in size-adjusted LSBMC (p=0.05); 0.04 SD decrease in LSBMAD (p=0.04) per 1% increase in uc-OC). CONCLUSION: Markers suggestive of sub-optimal vitamin K status and low bone formation were present despite normal size-adjusted bone mass. The association between LSBMC and % uc-OC is consistent with the hypothesis that sub-optimal vitamin K status is a risk factor for CF bone disease. This should ideally be investigated in an intervention trial.     

Low dietary riboflavin but not folate predicts increased fracture risk in postmenopausal women homozygous for the MTHFR 677 T allele.

The MTHFR C677T polymorphism is associated with mildly elevated homocysteine levels when folate and/or riboflavin status is low. Furthermore, a mildly elevated homocysteine level is a risk factor for osteoporotic fractures. We studied whether dietary intake of riboflavin and folate modifies the effects of the MTHFR C677T variant on fracture risk in 5,035 men and women from the Rotterdam Study. We found that the MTHFR C677T variant interacts with dietary riboflavin intake to influence fracture risk in women. INTRODUCTION: The MTHFR C677T polymorphism is associated with mildly elevated homocysteine (Hcy) levels in the presence of low folate and/or riboflavin status. A mildly elevated Hcy level was recently identified as a modifiable risk factor for osteoporotic fracture. We studied whether dietary intake of riboflavin and folate modifies the effects of the MTHFR C677T polymorphism on BMD and fracture risk. MATERIALS AND METHODS: We studied 5,035 individuals from the Rotterdam Study, >or=55 yr of age, who had data available on MTHFR, nutrient intake, and fracture risk. We performed analysis on Hcy levels in a total of 666 individuals, whereas BMD data were present for 4,646 individuals (2,692 women). RESULTS: In the total population, neither the MTHFR C677T polymorphism nor low riboflavin intake was associated with fracture risk and BMD. However, in the lowest quartile of riboflavin intake, female 677-T homozygotes had a 1.8 (95% CI: 1.1-2.9, p = 0.01) times higher risk for incident osteoporotic fractures and a 2.6 (95% CI: 1.3-5.1, p = 0.01) times higher risk for fragility fractures compared with the 677-CC genotype (interaction, p = 0.0002). This effect was not seen for baseline BMD in both men and women. No significant influence was found for dietary folate intake on the association between the MTHFR C677T genotype and fracture risk or BMD. In the lowest quartile of dietary riboflavin intake, T-homozygous individuals (men and women combined) had higher (22.5%) Hcy levels compared with C-homozygotes (mean difference = 3.44 microM, p = 0. 01; trend, p = 0.02). CONCLUSIONS: In this cohort of elderly whites, the MTHFR C677T variant interacts with dietary riboflavin intake to influence fracture risk in women.     

Microradiography and light microscopy of mineralization in the pulp of undemineralized human primary molars

This study was undertaken to investigate the prevalence, location and histologic features of the different types of mineralization observed in the pulp of human primary molars. Microradiography and light microscopy of undemineralized material disclosed that 95% of primary molars contain pulp calcifications. Histologically, their structure may be classified into four different types: (1) pulp stones, (2) diffuse calcifications, (3) eburnoid tissue and (4) spherulitic calcifications.     

Bioavailability of calcium from oyster shell electrolysate and DL-Calcium lactate in vitamin D-replete or vitamin D-deficient rats

Bioavailability of calcium (Ca) from oyster shell electrolysate (Active Absorbable Ca: AACa) and DL-Ca lactate in rats was investigated. Plasma Ca metabolism, bone mineral density and vitamin D-deficient rats were measured and compared each other. Vitamin D-deficient rats were fedad libitum a vitamin D-free diet containing 0.44 % Ca or 1.20 % Ca adjusted with either AACa or DL-Ca lactate with or without oral supplementation of physiological dose (10 IU/rat/day) of vitamin D₃ for 28 days. During and after feeding, concentrations of Ca, phosphorus, parathyroid hormone (PTH), 25-hydroxyvitamin D₃ (25-OH-D₃), 1α, 25-dihydroxyvitamin D₃ [1, 25(OH)₂D₃] and alkaline phosphatase (Alp) activity in plasma were measured. Furthermore, femoral Ca and phosphorus contents, mineral density and mechanical strength were also measured. Despite of the differences of contents and chemical forms of Ca in diets, all the groups showed prompt and complete recoveries in both Ca and vitamin D malnutritions under vitamin D-replete condition and there was no significant difference among all the groups in increases of body weight gains and plasma Ca levels, and in decreases of plasma PTH level and Alp activity. In contrast, the groups fed the same diets under vitamin D-deficient condition showed no significant recoveries in both plasma Ca metabolism and bone mineralization although Ca bioavailability of AACa appeared to be slightly better than that of DL-Ca lactate. These results suggest that bioavailability of Ca from AACa and DL-Ca lactate are substantially equal in increasing plasma Ca levels, bone mineral density and mechanical strength in both vitamin D-replete and vitamin D-deficient rats.     

The effect of aluminum on the metabolism of embryonic chick bone in tissue culture

The effect of aluminum (Al) on bone metabolism was assessed in organ cultures of embryonic chick bone. Al of 10^?4 M and above caused an inhibitory effect on mineralization without inhibiting matrix formation and a stimulative effect on demineralization without stimulating matrix degradation. Therefore, Al was shown to influence the mineral metabolism of bone.     

Osteoblast differentiation is impaired in SOCS-1-deficient mice

The suppressor of cytokine signaling-1 (SOCS-1) is a cytokine-inducible intracellular molecule that inhibits excessive activation of the JAK-STAT-mediated signal cascade initiated by various stimuli. The smaller size of SOCS-1 knockout (KO) mice suggests the presence of skeletal abnormality caused by the disruption of the regulatory system in JAK-STAT signaling. In addition to macroscopic examination, peripheral quantitative computed tomography (pQCT), bone histomorphometrical analysis, and in situ hybridization were used to examine the skeletal properties of SOCS-1 KO mice. Moreover, differentiation of primary cultured osteoblasts was investigated. Distinct phosphorylation of STAT1 was detected in the SOCS-1 KO calvarial cells but was hardly detectable in wild-type (WT) mice. Undercalcified areas in the skulls and sternum, as well as comparatively thinner calcified areas of cortical bone, were found in SOCS-1 KO mice. pQCT analysis showed a marked decrease in salt content, whereas the mineralization activity of primary cultured calvarial cells strongly suggested significant impairment in osteoblasts of SOCS-1 KO mice. In situ hybridization analysis demonstrated that these mice expressed the early markers [type I collagen (COL-1) and osteonectin (ON)] and the mid-marker [osteopontin (OP)] at levels comparable with those seen in WT mice. However, a dramatic decrease was observed in the expression level of the late marker [osteocalcin (OC)] of osteoblasts. Our findings thus demonstrate that SOCS-1 regulates osteoblast differentiation in the later stage.