3D-printed PCL framework assembling ECM-inspired multi-layer mineralized GO-Col-HAp microscaffold for in situ mandibular bone regeneration.

BACKGROUND: In recent years, natural bone extracellular matrix (ECM)-inspired materials have found widespread application as scaffolds for bone tissue engineering. However, the challenge of creating scaffolds that mimic natural bone ECM's mechanical strength and hierarchical nano-micro-macro structures remains. The purposes of this study were to introduce an innovative bone ECM-inspired scaffold that integrates a 3D-printed framework with hydroxyapatite (HAp) mineralized graphene oxide-collagen (GO-Col) microscaffolds and find its application in the repair of mandibular bone defects. METHODS: Initially, a 3D-printed polycaprolactone (PCL) scaffold was designed with cubic disks and square pores to mimic the macrostructure of bone ECM. Subsequently, we developed multi-layer mineralized GO-Col-HAp microscaffolds (MLM GCH) to simulate natural bone ECM's nano- and microstructural features. Systematic in vitro and in vivo experiments were introduced to evaluate the ECM-inspired structure of the scaffold and to explore its effect on cell proliferation and its ability to repair rat bone defects. RESULTS: The resultant MLM GCH/PCL composite scaffolds exhibited robust mechanical strength and ample assembly space. Moreover, the ECM-inspired MLM GCH microscaffolds displayed favorable attributes such as water absorption and retention and demonstrated promising cell adsorption, proliferation, and osteogenic differentiation in vitro. The MLM GCH/PCL composite scaffolds exhibited successful bone regeneration within mandibular bone defects in vivo. CONCLUSIONS: This study presents a well-conceived strategy for fabricating ECM-inspired scaffolds by integrating 3D-printed PCL frameworks with multilayer mineralized porous microscaffolds, enhancing cell proliferation, osteogenic differentiation, and bone regeneration. This construction approach holds the potential for extension to various other biomaterial types.

Crystalline analysis of dental enamel by X-Ray diffraction on pediatric patients with chronic kidney disease.

This study aimed to analyze the crystalline structure of dental enamel in pediatric patients with chronic kidney disease (CKD) by X-ray diffraction (XRD). The six tested samples had a mineral composition similar to hydroxyapatite, according to sheet JCPDS(Joint Committee on Powder Diffraction Standards) card #09-0432, which is normally found in dentine, and presented a lower amount of whitlockites (Ca, Mg)3(PO4)2. Pattern phases showed an increase in organic matter and a decrease in inorganic matter. At an interval of approximately 2θ = 15.7° to 27.2°, amorphous organic matter corresponding to hydrated glucose was found. The hydroxyapatite patterns in this study differed from that of dental enamel found on permanent teeth.

Synchrotron radiation analysis of root dentin: the roles of fluoride and calcium ions in hydroxyapatite remineralization.

Although the use of fluoride for root caries control is reported to be effective, the mechanism of maintaining hydroxyapatite is still unclear. This study elucidates the roles of fluoride in the recrystallization of hydroxyapatite, and the impact of calcium to maintain the abundance of hydroxyapatite on acid-challenged root dentin with a novel approach - using synchrotron radiation. Root dentin samples obtained from 40 extracted human premolars were subjected to pH challenge in combination with fluoride treatment. The effect of fluoride on hydroxyapatite regeneration on the root was investigated by using a range of fluoride concentrations (1000-5000 p.p.m.) and the EDTA-chelation technique in vitro. Synchrotron radiation X-ray micro-computed tomography and X-ray absorption spectroscopy were utilized to characterize the chemical composition of calcium species on the surface of prepared samples. The percentage of hydroxyapatite and the relative abundance of calcium species were subsequently compared between groups. The absence of calcium or fluoride prevented the complete remineralization of hydroxyapatite on the surface of early root caries. Different concentrations of fluoride exposure did not affect the relative abundance of hydroxyapatite. Sufficient potency of 1000 p.p.m. fluoride solution in promoting hydroxyapatite structural recrystallization on the root was demonstrated. Both calcium and fluoride ions are prerequisites in a caries-prone environment. Orchestration of F- and Ca2+ is required for structural homeostasis of root dentin during acid attack. Sustainable levels of F- and Ca2+ might thus be a strict requirement in the saliva of the population prone to root caries. Fluoride and calcium contribute to structural homeostasis of tooth root, highlighting that routine fluoride use in combination with calcium replenishment is recommended for maintaining dental health. This study also demonstrates that utilization of synchrotron radiation could provide a promising experimental platform for laboratory investigation especially in the dental material research field.

Synergistic impact of platelet rich plasma-heparin sulfate with hydroxyapatite/zirconia on the osteoblast differentiation potential of adipose-derived mesenchymal stem cells.

3D porous hydroxyapatite (HA) has been reinforced by zirconia (ZrO2) coating and impregnation with a combination of platelet rich plasma (PRP) as a source of growth factors (GFs) and Heparin sulfate (HS) to sustain the release of GFs. Adipose mesenchymal stem cells (ADMSCs) were characterized by flow cytometry for CD (cluster of differentiation) 44, CD105, CD106, CD34 and CD144, along with checking the multipotency by differentiation into the adipocytes and osteoblasts. Then, they were cultured on the scaffold treated with and without osteogenic media on days 7, 14 and 21. Electron micrograph and PKH staining show that the ADMSCs have a fusiform phenotype in the absence of osteogenic induction. Cell viability assay shows a higher number of the viable cells on the PRP-containing scaffolds than PRP-free scaffolds on day 7. Colorimetric evaluation, quantitative RT-PCR and immunocytochemistry demonstrate that PRP and HS significantly elevate the alkaline phosphatase enzyme activity and also accelerate the production of both early and mid-osteogenic markers, including collagen I and osteopontin expression with and without osteogenic conditions. The PRP-HS also accelerates the expression of the late osteogenic marker, osteocalcin, in both mRNA and protein level expression with a peak on day 21. In conclusion, supplementation of HA/ZrO2 with PRP/HS has a synergistic impact on the ADMSCs, even in the absence of chemical induction. It seems that HA/ZrO2/PRP/HS scaffold provides a higher osteoconductive microenvironment for stem cell differentiation to osteoblasts.

The development of a tool to predict temperature-exposure of incinerated teeth using colourimetric and hydroxyapatite crystal size data.

This study presents a novel tool to predict temperature-exposure of incinerated pig teeth as a proxy for understanding impacts of fire on human teeth. Previous studies on the estimation of temperature-exposure of skeletal elements have been limited to that of heat-exposed bone. This predictive tool was developed using a multinomial regression model of colourimetric and hydroxyapatite crystal size variables using data obtained from unheated pig teeth and teeth incinerated at 300 °C, 600 °C, 800 °C and 1000 °C. An additional variable based on the observed appearance of the tooth was included in the tool. This enables the tooth to be classified as definitely burnt (600 °C-1000 °C) or uncertain (27 °C/300 °C). As a result, the model predicting the temperature-exposure of the incinerated teeth had an accuracy of 95%. This tool is a holistic, robust and reliable approach to estimate temperature of heat-exposed pig teeth, with high accuracy, and may act as a valuable proxy to estimate heat exposure for human teeth in forensic casework.

Particle size matters: The effect of particle size on carbon and oxygen isotope composition of bone hydroxyapatite.

OBJECTIVES: Stable isotope studies often focus on hydroxyapatite (bioapatite) to answer questions of paleodiet, paleomobility, and paeloenvironment. This study seeks to determine the effect that sample particle size (in particular SA:V, or surface area to volume ratios) has on measured carbon and oxygen stable isotope values (δ13 C and δ18 O) in bone hydroxyapatite. MATERIALS AND METHODS: Previously ground Homo sapiens sapiens cortical bone samples were subdivided using geological screens to obtain three separate sub-samples, differing only in their particle size. These aliquots (n = 60) were then treated using established protocols to remove any exogenous organic material (2.5% NaOH) and adsorbed carbonates (0.1 M CH3 COOH), and analyzed for δ13 C and δ18 O using a Kiel-IV Carbonate Device coupled to a Thermo-Finnigan DeltaPlus IRMS. RESULTS: Data obtained indicate that decreased particle size leads to increases in both δ13 C and δ18 O, with oxygen isotope values being more dramatically affected. Specifically, it is possible to produce isotopic shifts of as much as 1.0‰ and 4.0‰ for δ13 C and δ18 O, respectively, solely by analyzing different sized particles from the same individual, bone, and sample. DISCUSSION: Based upon the variability seen between different size fractions from the same sample, it is clear that particle size has a meaningful impact on carbon and oxygen isotope composition. We attribute these shifts to the differential adsorption or precipitation of environmental carbon and oxygen during pretreatment. We recommend that particle size be added to the list of potential variables affecting isotope composition, alongside other factors including diagenesis, reagent concentration, and treatment time. We would also note that while most individuals exhibit consistent changes, some do not, and thus further investigation into these phenomena is warranted.

An isotopic study of dietary diversity in formative period Ancachi/Quillagua, Atacama Desert, northern Chile.

OBJECTIVES: To characterize the paleodiet of individuals from Formative Period (1500 B.C.-A.D. 400) Atacama Desert sites of Ancachi and Quillagua as a means of understanding the dietary and cultural impacts of regional systems of exchange. MATERIALS AND METHODS: Thirty-one bone samples recovered from the cemetery of Ancachi (02QU175) and in/around the nearby town of Quillagua were the subject of carbon and nitrogen stable isotope analysis of bone collagen and hydroxyapatite and multisource mixture modeling (FRUITS, food reconstruction using isotopic transferred signals) of paleodiet. These individuals were compared with nearly 200 other Formative Period individuals from throughout the region to identify differences in dietary behaviors. RESULTS: 80.6% (25/31) of the samples yielded sufficient well-preserved collagen and were included in the multisource mixture model. The FRUITS model, which compared individuals with a robust database of available foods from the region, identified a wide diversity of diets in the Ancachi/Quillagua area (including both coastal and interior individuals), and, most notably, thirteen individuals who consumed an average of 11.2 ± 1.9% terrestrial animals, 19.8 ± 1.9% legumes, and 22.5 ± 3.1% marine fauna, a balanced pattern of protein consumption distinct from both the coastal and inland individuals in our larger regional sample. CONCLUSIONS: The combination of stable isotope analysis and multisource mixture modeling permitted the characterization of dietary behavior of 25 individuals from nodal sites in the Atacama Desert, thus enhancing our understanding of the economic and social relationships that bound together Formative Period sites, populations, and individuals in this hyperarid region.

Raman spectroscopy of osteosarcoma cells.

Osteosarcoma is the most common primary malignant bone tumor. In the last years, several studies have demonstrated that the increase of Hydroxyapatite (HA) and Interleukin-6 (IL-6) syntheses compared to those expressed by normal osteoblasts could be used to detect the degree of malignancy of osteosarcoma cells. Conventional biochemical methods widely employed to evaluate bone cell differentiation, including normal and cancerous phenotypes, are time consuming and may require a large amount of cells. HA is a mineral form of calcium phosphate whose presence increases with maturation of osteosarcoma cells. Analogously, IL-6 is a fundamental cytokine whose production is highly increased in osteosarcoma cells. In this study, we employ Raman spectroscopy to the identification and discrimination of osteosarcoma cells from osteo-differentiated mesenchymal stromal cells (MSCs) by detecting the presence of HA and IL-6. However, while the identification of HA is facilitated by the characteristic peak at 960 cm-1, corresponding to symmetric stretching (P-O) mode, the quantification of IL-6 it is much more elusive, being its Raman signal characterized by cysteine, but also by phenylalanine, amide I II and III whose signals are common to other proteins. Supported by an accurate multivariate analysis, the results show that Raman spectroscopy is a high sensitivity technique dealing out a direct and quantitative measurement of specific mineralization levels of osteosarcoma cells. In turn, by exploiting the Surface-Enhanced Raman Scattering stimulated by internalized Gold Nanoshells (AuNSs) and combined with scanning probe microscopies, we were able to employ Raman spectroscopy to study subcellular components locally.

A Newly Developed mm-Wave Sensor for Detecting Plaques of Arterial Vessels.

BACKGROUND: Microcalcifications within the fibrous cap of the arteriosclerotic plaques lead to the accrual of plaque-destabilizing mechanical stress. New techniques for plaque screening with small detectors and the ability to differentiate between the smooth and hard elements of plaque formation are necessary. METHOD: Vascular plaque formations are characterized as calcium phosphate containing structures organized as hydroxylapatite resembling the mineral whitlockite. In transmission and reflexion studies with a simple millimeter wave (mm-wave)-demonstrator, we found that there is a narrow window for plaque detection in arterial vessels because of the tissue water content, the differentiation to fatty tissue, and the dielectric property of air or water, respectively. RESULT: The new sensor is based on a sensing oscillator working around 27 GHz. The open-stub capacitance determines the operating frequency of the sensor oscillator. The capacitance depends on the dielectric properties of the surrounding material. The sensor components were completely built up in surface mount technique. CONCLUSION: Completed with a catheter, the sensor based on microwave technology appears as a robust tool ready for further clinical use.

Estimated depth of apatite and collagen degradation in human dentine by sequential exposure to sodium hypochlorite and EDTA: a quantitative FTIR study.

AIM: To characterize chemical degradation of the principal constituents of dentine after exposure to NaOCl and EDTA using Infrared Spectroscopy (ATR-FTIR). METHODOLOGY: Ground dentine particles, from extracted permanent human molars, were passed through sieves of 38 to 1 000 µm to provide six size ranges. Portions (250 mg) of each size range were reacted with 5 mL of 2.5% NaOCl for 2-10 min; or 17% EDTA for 5-1440 min. Powders larger than 75 µm were also sequentially exposed to NaOCl/EDTA/NaOCl each for 10 min. All experiments were repeated five times. Reacted and unreacted powders were washed and dried. Particles larger than 75 µm were then reground. FTIR spectra of unground and reground reacted particles enabled assessment of particle surface versus bulk chemistry, respectively, plus estimation of reaction depth. Changes in the ratio of the 1 640 cm-1 collagen: 1 010 cm-1 phosphate peak height or its inverse were obtained. These were used to estimate surface and bulk fraction reacted and thus depth to which collagen or phosphate was reduced following immersion in NaOCl or EDTA, respectively. The data were analysed descriptively. RESULTS: Surface collagen fraction declined by ~40% within 2 min of NaOCl exposure, and plateaued at ~60% between 6-10 min. Bulk spectra showed average depth of collagen loss at 10 min was 16 ± 13 µm. Ten minute EDTA exposure caused ~60% loss of surface phosphate. Average depth of phosphate loss was 19 ± 12 µm and 89 ± 43 µm after 10 and 1 440 min EDTA immersion, respectively. Sequential NaOCl/EDTA immersion yielded a 62 ± 28 µm thick phosphate-depleted surface. Sequential NaOCl/EDTA/NaOCl treatment resulted in approximately 85 µm of collagen loss. CONCLUSIONS: Data revealed the sequential depletion of collagen by NaOCl and apatite by EDTA in dentine, simultaneously exposing the other moieties. Alternate exposure to NaOCl and EDTA therefore enhances the depth of erosion.

Feasibility of Spatially Offset Raman Spectroscopy for in Vitro and in Vivo Monitoring Mineralization of Bone Tissue Engineering Scaffolds.

We investigated the feasibility of using spatially offset Raman spectroscopy (SORS) for nondestructive characterization of bone tissue engineering scaffolds. The deep regions of these scaffolds, or scaffolds implanted subcutaneously in live animals, are typically difficult to measure by confocal Raman spectroscopy techniques because of the limited depth penetration of light caused by the high level of light scattering. Layered samples consisting of bioactive glass foams (IEIC16), three-dimensional (3D)-printed biodegradable poly(lactic-co-glycolic acid) scaffolds (PLGA), and hydroxyapatite powder (HA) were used to mimic nondestructive detection of biomineralization for intact real-size 3D tissue engineering constructs. SORS spectra were measured with a new SORS instrument using a digital micromirror device (DMD) to allow software selection of the spatial offsets. The results show that HA can be reliably detected at depths of 0-2.3 mm, which corresponds to the maximum accessible spatial offset of the current instrument. The intensity ratio of Raman bands associated with the scaffolds and HA with the spatial offset depended on the depth at which HA was located. Furthermore, we show the feasibility for in vivo monitoring mineralization of scaffold implanted subcutaneously by demonstrating the ability to measure transcutaneously Raman signals of the scaffolds and HA (fresh chicken skin used as a top layer). The ability to measure spectral depth profiles at high speed (5 s acquisition time) and the ease of implementation make SORS a promising approach for noninvasive characterization of cell/tissue development in vitro, and for long-term in vivo monitoring the mineralization in 3D scaffolds subcutaneously implanted in small animals.

X-ray diffraction analysis of spontaneously draining calcinosis in scleroderma patients.

OBJECTIVES: Calcium hydroxyapatite (HA) is reported to be the major constituent of soft tissue calcinosis in patients with scleroderma (systemic sclerosis, SSc). Mechanical stress and local tissue hypoxia are thought to be important in the pathogenesis of SSc calcinosis. We sought to analyse spontaneously draining material from calcinosis sites in SSc patients using X-ray diffraction (XRD). METHOD: With approval from our local Institutional Review Board (IRB), eligible SSc patients consented to submit their spontaneously draining calcinosis samples for XRD analysis. All patients met the American College of Rheumatology (ACR) criteria for definite SSc. XRD data were used to determine how much solid phase was present (e.g. HA vs. other calcium phosphate phases) and the percentage of crystalline components. Pertinent clinical data were collected. RESULTS: Draining calcinosis was submitted mostly from the hands of 10 female patients with advanced SSc, whose mean disease duration was 16 (range 9-29) years; six had diffuse cutaneous SSc and four had limited SSc. All 10 developed calcinosis later in their disease course; seven had extensive deposits affecting multiple sites. XRD confirmed that HA was the only crystalline material. However, HA was the minor component and most samples contained more than 50% organic material. Solid samples generally contained more HA and fluid samples contained HA in suspension. CONCLUSIONS: In this large series of SSc calcinosis analysis, XRD confirmed that HA was the only inorganic material that formed less than 50% of most draining samples. More research is needed to fully characterize and improve our understanding of calcinosis formation in SSc.

Carotid plaque instability is not related to quantity but to elemental composition of calcification.

BACKGROUND AND AIMS: Recent studies highlighted the role of calcification processes in the clinical progression of chronic cardiovascular diseases. In this study we investigated the relationship between the chemical composition of calcification and atherosclerotic plaque stability in carotid arteries. METHODS AND RESULTS: To this end, we characterized the calcification on 229 carotid plaques, by morphology, immunohistochemistry, transmission electron microscopy and energy dispersive X-ray microanalysis. Plaques were classified into two categories: unstable and stable. No significant differences were found in the incidence of the various risk factors between patients with and without carotid calcification, with the exception of diabetes. The energy dispersive X-ray microanalysis allowed us to identify two types of calcium salts in the atheromatous plaques, hydroxyapatite (HA) and calcium oxalate (CO). Our results showed that calcification is a common finding in carotid plaques, being present in 77.3% of cases, and the amount of calcium is not a factor of vulnerability. Noteworthy, we observed an association between HA calcification and unstable plaques. On the contrary, CO calcifications were mainly detected in stable plaques. CONCLUSIONS: The presence of different types of calcification in atheromatous plaques may open new perspectives in understanding the molecular mechanisms of atheroma formation and plaque instability.

Influence of trace elements on dental enamel properties: A review.

Dental enamel, an avascular, irreparable, outermost and protective layer of the human clinical crown has a potential to withstand the physico-chemical effects and forces. These properties are being regulated by a unique association among elements occurring in the crystallites setup of human dental enamel. Calcium and phosphate are the major components (hydroxyapatite) in addition to some trace elements which have a profound effect on enamel. The current review was planned to determine the aptitude of various trace elements to substitute and their influence on human dental enamel in terms of physical and chemical properties.

Comparative Evaluation of Effect of Nano-hydroxyapatite and 8% Arginine Containing Toothpastes in Managing Dentin Hypersensitivity: Double Blind Randomized Clinical Trial.

PURPOSE: This double blind randomized clinical trial was conducted with the purpose of evaluating the effects of Nano-hydroxyapatite toothpaste as compared to 8% Arginine containing toothpaste in the management of Dentin hypersensitivity (DH). METHOD AND MATERIALS: Patients (30 in each group) suffering from DH and eliciting a VAS score higher than 2 in air blast and tactile test were randomly allocated (block randomization) into either a group 1 (arginine toothpaste) or group 2 (nHA toothpaste). The primary outcome evaluated was the reduction of DH as measured by the electrical stimulus reading on the digital pulp tester. Current required for eliciting a VAS score of 2 was recorded before application of dentifrice. 1 cm of toothpaste was then expressed on the tooth surface for two minutes in each group and rinsed off. The electrical stimulus required to elicit a VAS score of 2 was recorded after 5 minutes, 1 week and 4 weeks. RESULTS: The desensitizing paste containing arginine provided a statistically significant reduction in DH and so did the paste containing nHA. Mean increase in amperage value (reduction in DH) was higher for nHA based than the arginine containing dentifrice. This difference was not statistically significant showing that both toothpastes are equally effective. CONCLUSIONS: The findings of the present study encourage the use of Nano-hydroxyapatite and arginine containing dentifrice as an effective desensitizing agent providing relief from symptoms 5 minutes after application and after 1 and 4 weeks.

Ca L2,3-edge XANES and Sr K-edge EXAFS study of hydroxyapatite and fossil bone apatite.

Upon burial, the organic and inorganic components of hard tissues such as bone, teeth, and tusks are subjected to various alterations as a result of interactions with the chemical milieu of soil, groundwater, and presence of microorganisms. In this study, simulation of the Ca L 2,3-edge X-ray absorption near edge structure (XANES) spectrum of hydroxyapatite, using the CTM4XAS code, reveals that the different symmetry of the two nonequivalent Ca(1) and Ca(2) sites in the unit cell gives rise to specific spectral features. Moreover, Ca L 2,3-edge XANES spectroscopy is applied in order to assess variations in fossil bone apatite crystallinity due to heavy bacterial alteration and catastrophic mineral dissolution, compared to well-preserved fossil apatite, fresh bone, and geologic apatite reference samples. Fossilization-induced chemical alterations are investigated by means of Ca L 2,3-edge XANES and scanning electron microscopy (SEM) and are related to histological evaluation using optical microscopy images. Finally, the variations in the bonding environment of Sr and its preference for substitution in the Ca(1) or Ca(2) sites upon increasing the Sr/Ca ratio is assessed by Sr K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy.

Characterization of nano-structural and nano-mechanical properties of osteoarthritic subchondral bone.

BACKGROUND: Although articular cartilage is the primary tissues affected by osteoarthritis (OA), the underlying subchondral bone also undergoes noticeable changes. Despite the growing body of research into the biophysical and mechanical properties of OA bone there are few studies that have analysed the structure of the subchondral sclerosis at the nanoscale. In this study, the composition and nano-structural changes of human osteoarthritis (OA) subchondral bone were investigated to better understand the site-specific changes. METHODS: OA bone samples were collected from patients undergoing total knee replacement surgery and graded according to disease severity (grade I: mild OA; grade IV: severe OA). Transmission electron microscopy (TEM), Electron Diffraction, and Elemental Analysis techniques were used to explore the cross-banding pattern, nature of mineral phase and orientation of the crystal lattice. Subchondral bone nano-hydroxyapatite powders were prepared and characterised using high resolution transmission electron microscopy (HR-TEM) and fourier transform infrared spectroscopy (FTIR). Subchondal bone mechanical properties were investigated using a nano-indentation method. RESULTS: In grade I subchondral bone samples, a regular periodic fibril banding pattern was observed and the c-axis orientation of the apatite crystals was parallel to the long axis of the fibrils. By contrast, in grade IV OA bone samples, the bulk of fibrils formed a random and undulated arrangement accompanied by a circular oriented pattern of apatite crystals. Fibrils in grade IV bone showed non-hierarchical intra-fibrillar mineralization and higher calcium (Ca) to phosphorous (P) (Ca/P) ratios. Grade IV OA bone showed higher crystallinity of the mineral content, increased modulus and hardness compared with grade I OA bone. CONCLUSIONS: The findings from this study suggest that OA subchondral sclerotic bone has an altered mineralization process which results in nano-structural changes of apatite crystals that is likely to account for the compromised mechanical properties of OA subchondral bones.

Bone computed tomography mineral content evaluation in chickens: effects of substances in homeopathic concentration.

METHODS: Ninety-six cobb race chickens were equally divided in 4 groups and randomly assigned to receive a standard treatment feed + homeopathic concentrations of Symphytum (S.) officinalis (9CH), or standard treatment feed + homeopathic concentrations of Tricalcarea (4CH), or standard treatment feed + homeopathic concentrations of Calcarea (C.) carbonica (30CH) or a placebo (the same feed but without any homeopathic compound) in order to assess the ability of the homeopathic compounds to increase the concentration of calcium hydroxyapatite in the sternal spongy bone tissue. We measured the concentration of calcium hydroxyapatite in the sternal spongy bone tissue of all chickens by means of a computed tomography (CT). RESULTS: 30%, 36% and 63% increase of sternum spongy-bone mineralization was observed after a 2 years period in the treatment groups with S. officinalis (9CH), Tricalcarea (4CH) (*P < 0.05) and C. carbonica (30CH) (***P < 0.001) respectively. CONCLUSION: Bone mineralization is usually low in battery chickens reared in commercial poultry-sheds, creating a weakness of the whole animal supporting apparatus. Homeopathic preparations with bone-tissue tropism may improve their health quality.

Remineralizing Effect of Topical NovaMin and Nano-hydroxyapatite on caries-like Lesions in Primary teeth.

INTRODUCTION: NovaMin is a synthetic mineral compound composed of calcium, sodium, phosphorus, and silica. It releases crystalline hydroxyl-carbonate apatite (HCA), which structurally resembles the minerals naturally found in the teeth. Nano-hydroxyapatite (NHA) is a biocompatible compound with high affinity for tooth enamel. NHA particles morphologically resemble dental enamel apatite crystals. Considering the efficacy of remineralizing agents and the importance of conservative preventive measures, this study aimed to compare the remin-eralizing effects of NovaMin and NHA on caries-like lesions in primary teeth. MATERIALS AND METHODS: This in vitro experimental study was conducted on 30 sound human primary anterior teeth with no cracks or fractures. The surface microhardness (SMH) of each tooth was measured at baseline using a Vickers microhard-ness tester. The teeth were then subjected to remineralization/ demineralization cycles, and artificial caries lesions were created in them. The SMH of each tooth was measured again and the teeth were then randomly treated with toothpastes containing NovaMin or 10% NHA powder for 2 minutes daily for a period of 5 days. The SMH of each was again measured afterward. Data were statistically analyzed using independent t-tests and Mann-Whitney U tests. RESULTS: The mean SMH was found to be higher in the teeth treated with NovaMin toothpaste (422.67 kgf/mm(2)) than in the teeth treated with NHA (384.2 kgf/mm(2)); However, this difference was not statistically significant. CONCLUSION: Both NHA and NovaMin were effective for reminer-alization of caries-like lesions of primary teeth and no significant difference was detected in their efficacy.

Comparative Quantitative Assessments of Salivary Ion Activity Product for Hydroxyapatite and Buffering Capacity in Children with Different Caries Experience.

AIM: If a relation exists between salivary IPHA, buffer capacity and caries experience, then this relationship could be used as screening chair side test for caries risk assessment. STUDY DESIGN: One hundred ninety seven children aged 4 to 6 years were examined. Data was collected by interview and clinical examination. They were divided into low, moderate and high caries experience group of 20 children each. Two ml of each sample was used to measure the pH value with pH meter. Regarding the buffering capacity, freshly prepared hydrochloric acid (HCl) was titrated into saliva and pH was recorded. The collected saliva samples were sent to Laboratory for measurement of calcium and phosphorus. IPHA was calculated and the negative logarithms of IPHA were used to determine the enamel solubility. The correlation between salivary IPHA, buffering capacity and caries experience were evaluated. RESULTS: There was a significant relation between pH, log IPHA and dental caries experience, it could be considered as a predictor of dental caries. CONCLUSION: pH measurement after HCl titration in saliva could be used as chair side screening test for the assessment of caries risk.