Dietary phosphorus burden increases cariogenesis independent of vitamin D uptake

Posteruptive Loss of Enamel Proteins Concurs with Gain in Enamel Hardness

Tooth enamel maturation requires the removal of proteins from the mineralizing enamel matrix to allow for crystallite growth until full hardness is reached to meet the mechanical needs of mastication. While this process takes up to several years in humans before the tooth erupts, it is greatly accelerated in in the faster developing pig. As a result, pig teeth erupt with softer, protein-rich enamel that is similar to hypomineralized human enamel but continues to harden quickly after eruption.Proteins, such as albumin, that bind to enamel crystals and prevent crystal growth and enamel hardening have been suggested as cause for hypomineralized human enamel that does not naturally harden after eruption. However, albumin is abundant in pig enamel. It is unclear whether fast posteruptive enamel hardening in pigs occurs despite the high protein content or requires a facilitated protein loss to allow for crystal growth. This study asked how the protein content in porcine enamel changes after eruption in relation to saliva. Based on previous data demonstrating the high albumin content in erupted porcine enamel, we hypothesize that following pre-eruptive maturation, enamel and saliva derived enzymes facilitate protein removal from porcine enamel after eruption. We analyzed enamel and the saliva proteome at three critical timepoints: at the time of tooth eruption, 2 weeks after eruption, and enamel 6 weeks after eruption. We used only fourth deciduous premolars and saliva samples from animals sacrificed at the respective time points to determine the organic content in tooth enamel, saliva, and saliva proteins within enamel. We found a decrease in the number of proteins and their abundancy in enamel with posteruptive time, including a decrease in serum albumin within enamel. The rapid decrease in the first two weeks is in line with previously reported rapid increase in mineral density of porcine enamel after eruption. In addition to the enamel proteases KLK-4 and MMP-20, we identified serine-, cysteine-, aspartic-, and metalloproteases. Some of these were only identified in enamel, while almost half of the enzymes are in common with saliva at all timepoints. Our findings suggest that the fast posteruptive enamel maturation in the porcine model coincides with saliva exchange and influx of saliva enzymes into porous enamel.

Beverage consumption and obesity in Kuwaiti school children

Sweetened beverage consumption is particularly important in countries such as Kuwait, where the prevalence of obesity is high, and most children drink sweetened beverages daily. To assess the relationship between three most commonly consumed beverages, (soda, milk, and juice) and the incidence of obesity among Kuwaiti children at the critical age of 10-12 year, Longitudinal cohort data of 6,305 children on initial presentation in 2012 (age, 10 years) and follow-up in 2014 (age, 12 years) were obtained from the Kuwait Healthy Life Study. The servings for the three beverages (soda, juice, and milk) were calculated as servings per day groups (0, 1-2, and 3 servings/day or more). Multivariate logistic regression was performed to assess the relationship between developing obesity during 2012-2014 and soda, juice, and milk consumption. Model selection was based on clinically relevant covariates and potential confounders using stepwise model selection. Six percent children become obese between baseline and follow-up visits. High soda drinking showed significant association with developing obesity. High milk consumption (more than 3 servings a day) was also significantly associated with developing obesity. Potential confounders included in the final model were age, sex, governorates, and fitness level, of which none were significant confounders or effect modifiers for the association. Children with high soda consumption had significantly higher prevalence of obesity. High obesity prevalence was observed with high milk consumption at a lower significance level but not with high juice consumption.

Cinnamic acid derivatives as potential matrix metalloproteinase-9 inhibitors: molecular docking and dynamics simulations

Matrix metalloproteinase-9 (MMP-9) is a zinc and calcium-dependent proteolytic enzyme involved in extracellular matrix degradation. Overexpression of MMP-9 has been confirmed in several disorders, including cancers, Alzheimer′s disease, autoimmune diseases, cardiovascular diseases, and dental caries. Therefore, MMP-9 inhibition is recommended as a therapeutic strategy for combating various diseases. Cinnamic acid derivatives have shown therapeutic effects in different cancers, Alzheimer′s disease, cardiovascular diseases, and dental caries. A computational drug discovery approach was performed to evaluate the binding affinity of selected cinnamic acid derivatives to the MMP-9 active site. The stability of docked poses for top-ranked compounds was also examined. Twelve herbal cinnamic acid derivatives were tested for possible MMP-9 inhibition using the AutoDock 4.0 tool. The stability of the docked poses for the most potent MMP-9 inhibitors was assessed by molecular dynamics (MD) in 10 nanosecond simulations. Interactions between the best MMP-9 inhibitors in this study and residues incorporated in the MMP-9 active site were studied before and after MD simulations. Cynarin, chlorogenic acid, and rosmarinic acid revealed a considerable binding affinity to the MMP-9 catalytic domain (ΔGbinding < -10 kcal/mol). The inhibition constant value for cynarin and chlorogenic acid were calculated at the picomolar scale and assigned as the most potent MMP-9 inhibitor from the cinnamic acid derivatives. The root-mean-square deviations for cynarin and chlorogenic acid were below 2 Å in the 10 ns simulation. Cynarin, chlorogenic acid, and rosmarinic acid might be considered drug candidates for MMP-9 inhibition.

Phosphate Dysregulation and Metabolic Syndrome

Phosphorus is one of the most abundant minerals in the human body. It is essential for almost all biochemical activities through ATP formation, intracellular signal transduction, cell membrane formation, bone mineralization, DNA and RNA synthesis, and inflammation modulation through various inflammatory cytokines. Phosphorus levels must be optimally regulated, as any deviations may lead to substantial derangements in glucose homeostasis. Clinical studies have reported that hyperphosphatemia can increase an individual's risk of developing metabolic syndrome. High phosphate burden has been shown to impair glucose metabolism by impairing pancreatic insulin secretion and increasing the risk of cardiometabolic disorders. Phosphate toxicity deserves more attention as metabolic syndrome is being seen more frequently worldwide and should be investigated further to determine the underlying mechanism of how phosphate burden may increase the cardiometabolic risk in the general population.

Excessive Inorganic Phosphate Burden Perturbed Intracellular Signaling: Quantitative Proteomics and Phosphoproteomics Analyses

Inorganic phosphate (Pi) is an essential nutrient for the human body which exerts adverse health effects in excess and deficit. High Pi-mediated cytotoxicity has been shown to induce systemic organ damage, though the underlying molecular mechanisms are poorly understood. In this study, we employed proteomics and phosphoproteomics to analyze Pi-mediated changes in protein abundance and phosphorylation. Bioinformatic analyses and literature review revealed that the altered proteins and phosphorylation were enriched in signaling pathways and diverse biological processes. Western blot analysis confirms the extensive change in protein level and phosphorylation in key effectors that modulate pre-mRNA alternative splicing. Global proteome and phospho-profiling provide a bird-eye view of excessive Pi-rewired cell signaling networks, which deepens our understanding of the molecular mechanisms of phosphate toxicity.

Use of Micro-CT Imaging to Assess Ventral Mandibular Cortical Thickness and Volume in an Experimental Rodent Model With Chronic High-Phosphorus Intake

Adverse effects of high dietary phosphorus on bone health have been observed in both animal and human studies. The aim of the investigation was to examine chronic effects of high phosphorus diet on the apical mandibular cortical thickness and volume in a hystricomorph rodent (Octodon degus) using microcomputed tomography. Male degus were randomly divided into two groups fed by different mineral contents from the age of 12 weeks till the age of 17 months. The micro-CT scanning and wall thickness analysis were applied on the region of the mandible exactly under the apices of the 4th premolar tooth, first molar tooth, and second molar tooth in two animals from each group. General overview and mapping of the ventral mandibular bone thickness revealed pronounced bony mandibular protrusions in all the animals fed a high-phosphorus diet with obvious bone thinning apically to the 4th premolar and first and second molar tooth apices. Mandibular bone volume and thickness located apically to the premolar and molars were statistically significantly smaller/thinner in the group fed by a high phosphorus diet. The thinnest bone measured 0.004 mm, where the mandibular 4th premolar tooth almost perforated the mandibular cortex. Similar studies of metabolic bone disease and its influence on alveolar bone were also published in rats and mice. The influence of different environmental, infectious, or metabolic factors on the growing tooth, alveolar bone formation, and bone pathologies must be done experimentally on growing animals. In contrast, degus have continuously growing dentition, and the effect of any of the above listed factors can be studied in this animal model at any age and for longer time periods.

Inorganic phosphate-induced cytotoxicity

Phosphate, an essential nutrient, is available in organic and inorganic forms. The balance of phosphate is central for cellular homeostasis through the genomic roles of DNA and RNA synthesis and cell signaling processes. Therefore, an imbalance of this nutrient, manifested, either as a deficiency or excess in phosphate levels, can result in pathology, ranging from cytotoxicity to musculoskeletal defects. Inorganic phosphate (Pi) overdosing can result in a wide spectrum of cytotoxicity processes, as noted in both animal models and human studies. These include rewired cell signaling pathways, impaired bone mineralization, infertility, premature aging, vascular calcification, and renal dysfunction. This article briefly reviews the regulation of phosphate homeostasis and elaborates on cytotoxic effects of excessive Pi, as documented in cell-based models.

Evaluation of Vitamin D (25OHD), Bone Alkaline Phosphatase (BALP), Serum Calcium, Serum Phosphorus, Ionized Calcium in Patients with Mandibular Third Molar Impaction. An Observational Study

The aim of this study was to evaluate the levels of vitamin D (25OHD) and other bone biomarkers in patients with third molar impaction (TMI). Thirty males and 30 females with unilateral or bilateral impacted mandibular third molar, and 15 males and 15 females as a control group (CG) were recruited. Rx-OPT was used to evaluate dental position and Pederson index to measure the difficulty of the intervention. Bone biomarkers were measured through blood venous sample in TMI group and CG. Mann-Whitney test, Pearson’s correlation coefficient, linear regression model were used to compare the different parameters in the two groups. 25OHD showed lower values in TMI group than in CG (p < 0.05) with values significantly lower in bilateral impaction (p < 0.05). Pearson’s coefficient for 25OHD presented a negative correlation with the Pederson index (ρ = −0.75). Bone alkaline phosphatase (BALP) showed significantly lower dosage in TMI group than CG (p = 0.02), Pearson’s coefficient for BALP presented a negative correlation with the Pederson index. Serum calcium, serum phosphorus, ionized calcium levels in TMI and CG groups were similar and Mann-Whitney test did not significantly differ between TMI and CG. TMI could be a sign of vitamin D deficiency and of low BALP levels that should be investigated.

Associations Between Prenatal, Perinatal, and Early Childhood Vitamin D Status and Risk of Dental Caries at 6 Years

BACKGROUND

Previous studies have suggested that insufficient concentrations of vitamin D are associated with dental caries in primary teeth, but evidence remains inconclusive.

OBJECTIVES

We assessed the longitudinal associations between prenatal, perinatal, and early childhood serum 25-hydroxyvitamin D concentrations [25(OH)D] and the risk of dental caries in 6-year-old children.

METHODS

This research was conducted within the Generation R Study, a large, multi-ethnic, prospective cohort study located in Rotterdam, the Netherlands. Dental caries were assessed in children using the decayed-missing-filled-primary teeth index at a mean age of 6.1 years (90% range, 4.8-9.1). We measured serum total 25(OH)D concentrations at 3 time points: prenatally (at 18-24 weeks of gestation), perinatally (at birth), and during early childhood (at age 6 years). We performed logistic regression analyses to determine the longitudinal association of serum 25(OH)D concentrations with caries risks in 5257 children. Additionally, we constructed a Genetic Risk Score (GRS) for the genetic predispositions to serum total 25(OH)D concentrations based on 6 vitamin D-related single nucleotide polymorphisms in a subsample of 3385 children.

RESULTS

Children with severe prenatal and early childhood serum 25(OH)D deficiencies (<25 nmol/L) were more likely to be diagnosed with caries [OR, 1.56 (95% CI, 1.18-2.06) and 1.58 (95% CI, 1.10-2.25), respectively] than children with optimal concentrations (≥75 nmol/L). After adjustment for residuals of serum 25(OH)D concentrations at other time points, only the early childhood serum 25(OH)D concentration was inversely associated with the caries risk at 6 years (OR, 0.97; 95% CI, 0.95-0.98). However, our GRS analysis showed that children who are genetically predisposed to have lower serum 25(OH)D concentrations do not have a higher risk of developing caries in primary teeth.

CONCLUSIONS

Our study suggests a weak association between serum 25(OH)D concentrations and risks of caries in primary teeth. Based on our results, we do not recommend vitamin D supplementation for the prevention of dental caries in children.

Importance of Dietary Phosphorus for Bone Metabolism and Healthy Aging

Inorganic phosphate (Pi) plays a critical function in many tissues of the body: for example, as part of the hydroxyapatite in the skeleton and as a substrate for ATP synthesis. Pi is the main source of dietary phosphorus. Reduced bioavailability of Pi or excessive losses in the urine causes rickets and osteomalacia. While critical for health in normal amounts, dietary phosphorus is plentiful in the Western diet and is often added to foods as a preservative. This abundance of phosphorus may reduce longevity due to metabolic changes and tissue calcifications. In this review, we examine how dietary phosphorus is absorbed in the gut, current knowledge about Pi sensing, and endocrine regulation of Pi levels. Moreover, we also examine the roles of Pi in different tissues, the consequences of low and high dietary phosphorus in these tissues, and the implications for healthy aging.

High phosphate actively induces cytotoxicity by rewiring pro-survival and pro-apoptotic signaling networks in HEK293 and HeLa cells

Inorganic phosphate (Pi) is an essential nutrient for human health. Due to the changes in our dietary pattern, dietary Pi overload engenders systemic phosphotoxicity, including excessive Pi-related vascular calcification and chronic tissue injury. The molecular mechanisms of the seemingly distinct phenotypes remain elusive. In this study, we investigated Pi-mediated cellular response in HEK293 and HeLa cells. We found that abnormally high Pi directly mediates diverse cellular toxicity in a dose-dependent manner. Up to 10 mM extracellular Pi promotes cell proliferation by activating AKT signaling cascades and augmenting cell cycle progression. By introducing additional Pi, higher than the concentration of 40 mM, we observed significant cell damage caused by the interwoven Pi-related biological processes. Elevated Pi activates mitogen-activated protein kinase (MAPK) signaling, encompassing extracellular signal-regulated kinase 1/2 (ERK1/2), p38 and Jun amino-terminal kinase (JNK), which consequently potentiates Pi triggered lethal epithelial-mesenchymal transition (EMT). Synergistically, high Pi-caused endoplasmic reticulum (ER) stress also contributes to apparent apoptosis. To counteract, Pi-activated AKT signaling promotes cell survival by activating the mammalian target of rapamycin (mTOR) signaling and blocking ER stress. Pharmacologically or genetically abrogating Pi transport, the impact of high Pi-induced cytotoxicity could be reduced. Taken together, abnormally high extracellular Pi results in a broad spectrum of toxicity by rewiring complicated signaling networks that control cell growth, cell death, and homeostasis.

Overconsumption of sugar-sweetened beverages: Why is it difficult to control?

The consumption of sugar-sweetened beverages is a known contributory factor of childhood obesity that is documented around the globe. More importantly, reducing the consumption of sugar-sweetened beverages could reduce weight gain among overweight or obese children. Although sugar is present in many natural foods, artificial sugar is added into sugar-sweetened beverages, which has little or no nutritional value. However, the calories obtained from the sugar-sweetened beverages are linked to overweight and obesity, and an increase serving sizes of sugar-sweetened beverages over the years partly contributed to the alarming rise of childhood obesity around the globe. The sugar-sweetened beverages not only contain a high amount of sugar, but also contain a high amount of phosphate, and the possibility exists for an enhancing dual adverse health effects of sugar and phosphate. Increasing health awareness and limiting marketing approaches targeted towards the younger population are essential to reduce long-term health burdens that are linked to the overconsumption of sugar-sweetened beverages.

Zinc Adequacy Is Essential for the Maintenance of Optimal Oral Health

Zinc, a metal found in the Earth's crust, is indispensable for human health. In the human body, around 60% of zinc is present in muscles, 30% in bones, and the remaining 10% in skin, hair, pancreas, kidneys and plasma. An adequate zinc balance is essential for the maintenance of skeletal growth, development and function. It is also necessary for basic cellular functions including enzyme activation, cell signaling and energy metabolism. Inadequate zinc status is associated with a wide variety of systemic disorders including cardiovascular impairment, musculoskeletal dysfunctions and oromaxillary diseases. In this article, we briefly discuss the role of zinc deficiency in the genesis of various oromaxillary diseases, and explain why adequate zinc homeostasis is vital for the maintenance of oral and general health.

Use of an online medical database for clinical decision-making processes: assessment of knowledge, attitude, and practice of oral health care providers

Purpose: This study was conducted to determine the level of knowledge, attitude, and practice of oral health care providers toward the use of online medical databases for clinical decision-making processes. Subjects and methods: The study population included all the licensed oral health care providers living in Rwanda, registered either with the Rwanda Allied Health Professional Council (RAHPC) or Rwanda Medical and Dental Council (RMDC). A self-administered questionnaire was used to collect demographic data as well as data regarding knowledge, attitude, and practice of oral health care providers regarding the use of online medical databases for making clinical decisions. A pilot study with 12 oral health care providers was done before the main study to pretest the questionnaire. Results: The study results show that among the 201 respondents, 80% (N=160) reported using internet-based resources to support their clinical decisions, while 20% (N=41) of oral health care providers do not use online resources when making their clinical decisions. In general, there was a positive attitude towards internet-based resources among the participants, as 92% (N=184) respondents believe that internet-based resources are helpful in clinical decision-making processes. Of clinical importance, 68% respondents (N=136) believe that by using current internet-based information, better clinical care can be offered to their patients. Conclusion: Educating oral health care providers on the useful and appropriate online resources available for supporting clinical decision-making processes might increase the efficiency of patient care.

Dietary phosphorus enhances inflammatory response: A study of human gingivitis

Phosphates are associated with numerous disorders, ranging from vascular calcification to premature aging, possibly because of an increased inflammatory response. We therefore investigated the association of dietary phosphorus with gingivitis. We analyzed consumption of both phosphorus and sugar and related it to the concentrations of inflammatory biomarkers in saliva samples collected from 8314 children (mean age, 9.99 ± 0.68 years). About 64% of the children consumed more than 1250 mg phosphorus daily, and 34% consumed more than 82 g of sugar daily. Gingivitis was prevalent, with an average of 74% of possible gingival sites considered red. Quantile regression analysis revealed a statistically significant correlation between the occurrence of gingivitis and calorie-adjusted phosphorus intake and between gingivitis and calorie-adjusted sugar intake (both significant either as a linear trend or a categorical variable). In a subset (n = 744) investigation of nutrient consumption related to salivary biomarkers, we found that elevated calorie-adjusted phosphorus intake was directly associated with salivary IL-1β concentration (OR1.40, 95% CI 1.04-1.89), and inversely associated with salivary IL-4 concentration (OR0.62, 95% CI 0.46-0.84). Sugar intake was not significantly associated with either biomarker. Thus, elevated dietary phosphorus consumption may influence inflammatory disease by altering cytokine levels.

Magnesium: Are We Consuming Enough?

Magnesium is essential for maintaining normal cellular and organ function. In-adequate magnesium balance is associated with various disorders, such as skeletal deformities, cardiovascular diseases, and metabolic syndrome. Unfortunately, routinely measured serum magnesium levels do not always reflect total body magnesium status. Thus, normal blood magnesium levels eclipse the wide-spread magnesium deficiency. Other magnesium measuring methods, including the magnesium loading test, may provide more accurate reflections of total body magnesium status and thus improve identification of magnesium-deficient individuals, and prevent magnesium deficiency related complications.

Phosphate toxicity and tumorigenesis

In this article, we briefly summarized evidence that cellular phosphate burden from phosphate toxicity is a pathophysiological determinant of cancer cell growth. Tumor cells express more phosphate cotransporters and store more inorganic phosphate than normal cells, and dysregulated phosphate homeostasis is associated with the genesis of various human tumors. High dietary phosphate consumption causes the growth of lung and skin tumors in experimental animal models. Additional studies show that excessive phosphate burden induces growth-promoting cell signaling, stimulates neovascularization, and is associated with chromosome instability and metastasis. Studies have also shown phosphate is a mitogenic factor that affects various tumor cell growth. Among epidemiological evidence linking phosphate and tumor formation, the Health Professionals Follow-Up Study found that high dietary phosphate levels were independently associated with lethal and high-grade prostate cancer. Further research is needed to determine how excessive dietary phosphate consumption influences initiation and promotion of tumorigenesis, and to elucidate prognostic benefits of reducing phosphate burden to decrease tumor cell growth and delay metastatic progression. The results of such studies could provide the basis for therapeutic modulation of phosphate metabolism for improved patient outcome.

Effects of vitamin D status on oral health

Normal humans of all ages have the innate ability to produce vitamin D following sunlight exposure. Inadequate vitamin D status has shown to be associated with a wide variety of diseases, including oral health disorders. Insufficient sunlight exposure may accelerate some of these diseases, possibly due to impaired vitamin D synthesis. The beneficial effects of vitamin D on oral health are not only limited to the direct effects on the tooth mineralization, but are also exerted through the anti-inflammatory functions and the ability to stimulate the production of anti-microbial peptides. In this article, we will briefly discuss the genesis of various oral diseases due to inadequate vitamin D level in the body and elucidate the potential benefits of safe sunlight exposure for the maintenance of oral and general health.