Highest Calcium Release Research Articles

Mechanical Properties and Decomposition Behavior of Compression Moldable Poly(Malic Acid)/α-Tricalcium Phosphate Hybrid Materials.

Calcified tissues in living organisms, such as bone, dentin, and enamel, often require surgical intervention for treatment. However, advances in regenerative medicine have increased the demand for materials to assist in regenerating these tissues. Among the various forms of calcium phosphate (CaP), tricalcium phosphate (TCP)-particularly its α-TCP form-stands out due to its high solubility and efficient calcium release, making it a promising candidate for bone regeneration applications. Nevertheless, its rapid dissolution rate presents challenges when used as a reinforcing agent. In this study, we developed a hybrid material composed of poly(malic acid) (PMA) and α-TCP to achieve controlled calcium release while maintaining mechanical strength. The hybrid materials were prepared using a compression molding method optimized to suppress the hydrolysis of PMA. The bond between the carboxyl group of PMA and α-TCP was confirmed through infrared (IR) spectroscopy. A calcium release test demonstrated that the interaction between PMA and α-TCP extends the dissolution period of both components. These findings indicate that PMA/α-TCP hybrid materials have significant potential for applications in bone tissue engineering.

Assessment of Calcium Concentration and pH at the Periapical Environment on Placing Calcium Hydroxide with Different Natural Vehicles – An In vitro Study

Abstract Background: In root canal therapy, the number of microorganisms in canals can be controlled by giving proper intracanal medication dressing. Calcium concentration and changes in pH at the periapical region denote the effect of antibacterial action in the periapical region. Aim: The aim is to determine a suitable natural vehicle for calcium hydroxide (Ca(OH)2) as an intracanal medicament by assessing the calcium concentration and changes in pH at the periapical region. Materials and Methods: A total of 60 extracted single-rooted permanent teeth were equally allotted into four groups – Group I: Ca(OH)2 with distilled water, Group II: Ca(OH)2 with aloe vera, Group III: Ca(OH)2 with coconut water, and Group IV: Ca(OH)2 with neem extract. pH was determined by pH meter and calcium by chromatography. The values were taken on days 1, 2, 3, 7 and 14. Results: All the materials showed alkaline pH and release of calcium ion throughout the study. For day 1, the mean pH value was highest for distilled water (10.06) and lowest for aloe vera extract (9.42). The highest calcium release during day 1 was by coconut water (67.85) and the least calcium release was by aloe vera (42.01). On day 14, the highest calcium release was by distilled water (89.98) followed by coconut water (67.24) and least by neem extract (61.13). pH values and calcium release in four different natural vehicles were significant (P < 0.05). Conclusion: All natural materials used in this study showed good Ca(OH)2 diffusion when used as a vehicle with Ca(OH)2 in root canals.

Characterization and Assessment of Physical Properties of 3 Single Syringe Hydraulic Cement–based Sealers

IntroductionA number of sealers with different chemistries are badged as Bioceramic, implying biological activity, but have dissimilar properties, which has implications on the sealer properties and will affect the quality and outcome of root canal treatment. This study aimed to assess the physical and chemical properties of 3 hydraulic cement–based sealers, namely BC Universal sealer compared with Totalfill BC sealer and AH Plus Bioceramic. MethodsThe microstructure and composition of the sealers were assessed using scanning electron microscopy and energy dispersive spectroscopy after setting. The crystalline phases were assessed by X-ray diffraction analysis and the leachates were tested using inductively coupled plasma. All testing was performed at 0, 7, and 28 days. The physical properties of film thickness, flow, radiopacity, and solubility were evaluated using ISO 6876:2012 standards. ResultsAll 3 sealers contained calcium, zirconium, and silicon. Totalfill BC had the highest calcium release at 7 and 28 days followed by AH Plus Bioceramic and BC Universal sealer. All 3 sealers adhered to the ISO standard in terms of flow and radiopacity. BC Universal sealer was slightly over the range (>50 μm) for film thickness. All sealers exceeded the solubility range set by ISO 6876:2012. ConclusionAlthough these hydraulic cement sealers had similar components and delivery, the properties varied significantly. The testing of material properties to confirm the suitability for clinical use is necessary.

Ion release, biocompatibility, and bioactivity of resin-modified calcium hydroxide cavity liners

BackgroundThe placement of liners near the pulp area is essential for therapeutic effects and maintaining pulp health while stimulating the formation of tertiary dentin. This in vitro study aimed to evaluate the calcium release, pH, biocompatibility, solubility, and bioactivity of three resin-modified calcium hydroxide cavity liners.MethodsThe disc specimens of each cavity liner were prepared using polyethylene molds of 7 mm in diameter and 2 mm in height (n = 10). Three light-cure liners evaluated include Ultra-Blend Plus (UB), Base-it (BI), and Master Dent (MD). The samples were then immersed in flasks containing 10 mL of distilled water. Calcium ion release, pH, and solubility were evaluated in two weeks of incubation. The cytotoxicity of extracts adjacent to the specimens was evaluated by MTT assay using NIH/3T3 cells after 1, 3, and 7 days of incubation. The ability to induce the nucleation of calcium phosphates (CaPs) after 28-day immersion in a simulated body fluid was investigated by SEM-EDX analysis. Statistical analysis was performed using ANOVA, Kruskal-Wallis, and repeated measures tests at the significant level of 0.05.ResultsThere was a significant difference in the release of calcium ions among the three liners investigated on days 1, 7, and 14 (p < 0.05). UB liners exhibited a significantly higher amount of calcium release than the other two liners, followed by BI, and MD. On day 1, there was no significant difference in the average pH among the three liners. However, after day 7, the MD liner showed a significant decrease in pH compared to the other two liners. BI liner demonstrated the highest level of biocompatibility, followed by the MD and UB liners. UB showed a high calcium release, solubility with no alkalizing activity, and the formation of more mature Ca-rich apatite deposits than the other two liners.ConclusionBased on the results of this study, the cavity liner material’s performance is material dependent. It can impact ion release, biocompatibility, and bioactivity which are important factors to consider in clinical practice. Further studies are needed to investigate the long-term effects of different liner materials on oral tissues.

Use of Reflectometer Optipen to assess the preventive effect of a sugarcane cystatin on initial dental erosion in vivo

The sugarcane cystatin 5 (CaneCPI-5) showed protection against erosion and erosive tooth wear (ETW) under several protocols. However, evaluating these conditions in vivo is hard due to the lack of a suitable device. The aim of this study was to use clinically the relative surface reflection intensity (%SRI) by the Reflectometer Optipen to assess the acquired pellicle engineering with CaneCPI-5 rinse for the prevention of initial erosion in vivo. Nine volunteers were distributed in three cross-over phases, according to the rinse used, as follows: 1) Deionized water (negative control); 2) Elmex® (800 ppm Sn2+, 500 ppm F-; positive control); 3) 0.1 mg/mL CaneCPI-5. The following experimental steps were performed: Initially, the volunteers received prophylaxis and the initial %SRI was performed. Subsequently, they rinsed with the solutions (10 mL; 1min), followed by the formation of the acquired enamel pellicle (AEP; 120min). After, the erosive challenge with citric acid 1%, pH 2.5 (10 μL; 10s) was performed (in isolation) on the buccal surface of the maxillary central incisors (right and left). The calcium present in the acid was analyzed by Arsenazo III method. Finally, the final %SRI was performed. Data were analyzed by Kruskal-Wallis/Dunn's tests and Spearman's correlation were used (p < 0.05). For both variables, the negative control led to significantly less protection (lower reflectivity and higher calcium release) in comparison with the other groups. The best protection (higher reflectivity and lower calcium release) was observed for the Elmex® and the CaneCPI-5 groups, with no significant differences between them (p < 0.05). There was a significant correlation between both analyzes. The Reflectometer Optipen demonstrated to be a good device to assess clinically. Moreover, CaneCPI-5 rinse proved effective through acquired pellicle engineering against initial erosion in vivo.

Chemical-Physical Properties and Bioactivity of New Premixed Calcium Silicate-Bioceramic Root Canal Sealers.

The aim of the study was to analyze the chemical-physical properties and bioactivity (apatite-forming ability) of three recently introduced premixed bioceramic root canal sealers containing varied amounts of different calcium silicates (CaSi): a dicalcium and tricalcium silicate (1-10% and 20-30%)-containing sealer with zirconium dioxide and tricalcium aluminate (CERASEAL); a tricalcium silicate (5-15%)-containing sealer with zirconium dioxide, dimethyl sulfoxide and lithium carbonate (AH PLUS BIOCERAMIC) and a dicalcium and tricalcium silicate (10% and 25%)-containing sealer with calcium aluminate, tricalcium aluminate and tantalite (NEOSEALER FLO). An epoxy resin-based sealer (AH PLUS) was used as control. The initial and final setting times, radiopacity, flowability, film thickness, open pore volume, water absorption, solubility, calcium release and alkalizing activity were tested. The nucleation of calcium phosphates and/or apatite after 28 days aging in Hanks balanced salt solution (HBSS) was evaluated by ESEM-EDX, vibrational IR and micro-Raman spectroscopy. The analyses showed for NeoSealer Flo and AH Plus the longest final setting times (1344 ± 60 and 1300 ± 60 min, respectively), while shorter times for AH Plus Bioceramic and Ceraseal (660 ± 60 and 720 ± 60 min, respectively). Radiopacity, flowability and film thickness complied with ISO 6876/12 for all tested materials. A significantly higher open pore volume was observed for NeoSealer Flo, AH Plus Bioceramic and Ceraseal when compared to AH Plus (p &lt; 0.05), significantly higher values were observed for NeoSealer Flo and AH Plus Bioceramic (p &lt; 0.05). Ceraseal and AH Plus revealed the lowest solubility. All CaSi-containing sealers released calcium and alkalized the soaking water. After 28 days immersion in HBSS, ESEM-EDX analyses revealed the formation of a mineral layer that covered the surface of all bioceramic sealers, with a lower detection of radiopacifiers (Zirconium for Ceraseal and AH Plus Bioceramic, Tantalum for NeoSealer Flo) and an increase in calcium, phosphorous and carbon. The calcium phosphate (CaP) layer was more evident on NeoSealer Flo and AH Plus Bioceramic. IR and micro-Raman revealed the formation of calcium carbonate on the surface of all set materials. A thin layer of a CaP phase was detected only on AH Plus Bioceramic and NeoSealer Flo. Ceraseal did not show CaP deposit despite its highest calcium release among all the tested CaSi-containing sealers. In conclusion, CaSi-containing sealers met the required chemical and physical standards and released biologically relevant ions. Slight/limited apatite nucleation was observed in relation to the high carbonation processes.

Comparative Study for Flue Dust Stabilization in Cement and Glass Materials: A Stability Assessment of Arsenic

Arsenic is a poisonous element and its super mobility can pose a major threat to the environment and human beings. Disposed arsenic-bearing waste or minerals over time may release arsenic into the groundwater, soil and then the food chain. Consequently, safe landfill deposition should be carried out to minimize arsenic bleeding. Cement-based stabilization/solidification and glass vitrification are two important methods for arsenic immobilization. This work compares the stability and intrinsic leaching properties of sequestered arsenic by cement encapsulation and glass vitrification of smelter high-arsenic flue dust (60% As2O3) and confirms if they meet or exceed the requirement of landfill disposition over a range of environmentally relevant conditions. The toxicity characterization leaching procedure (TCLP, 1311), synthetic precipitation leaching procedure (SPLP, 1312) and Australian standard (Aus. 4439.3) in short-term (18 h) and mass transfer from monolithic material using a semi-dynamic leaching tank (1315) in longer-term (165 days) were employed to assess arsenic immobility characteristic in three arsenic-cement (2%, 8.4% and 14.4%) and arsenic-glass (11.7%) samples. Moreover, calcium release from different matrices has been taken into consideration as a contributor to arsenic bleeding. Based on the USEPA guidelines, samples can be acceptable for landfilling only if As release is &lt;5 mg/L. Results obtained from short-term leaching were almost similar for both cement and glass materials. However, high calcium release was observed from the cement-encapsulated materials. The pH of leachates after the test was highly alkaline for encapsulated materials; however, in glass material it was near neutral or slightly acidic. Method 1315 tests made a huge difference between the two materials and confirmed that cement encapsulation is not the best method for landfilling arsenic waste due to the high arsenic and calcium release over time with alkaline pH. However, glass material has shown promising results, i.e., the insignificant release of arsenic over time with an acceptable change in pH value. Overall, arsenic sequestration in glass is a better option compared with the cement-based solidification process.

Bioceramics in Vital Pulp Therapy

The goal of vital pulp therapy (VPT) is to protect and maintain the vitality of pulp ally involved teeth that have been compromised by pulpal diseases. Due to a greater understanding of pulp physiology and bio ceramic materials linked with adhesive technology, significant progress has been made in this field. The enhanced biological competence related to the high pH and long-term calcium release are the main features of bioceramics which are intended to improve the clinical outcome of pulp capping procedures. In this article, we would discuss bio ceramics and their role in improving clinical outcomes in vital pulp therapy. Keywords: Vital pulp therapy, bioceramics.

Effects of different calcium salts on the physicochemical properties of sliver carp myosin

To investigate the effects of different calcium salts on the physicochemical properties of myosin, the intermolecular interactions, particle size, surface hydrophobicity, reactive sulfhydryl group content and rheological properties of sliver carp myosin with the addition of four different kinds of calcium salts (CaCl2, calcium citrate (CC), nano-hydroxyapatite (HAP), tricalcium phosphate (TCP)) during gel processing were measured. The results showed that the addition of CaCl2 promoted the unwinding of α-helix, the increase in hydrophobic interactions, the formation of disulfide bonds of myosin, and increased the viscoelasticity of myosin. While, the addition of calcium citrate (CC) enhanced the hydrophobic interaction between myosin molecules, and the viscoelasticity of CC-added myosin was second only to the CaCl2-added myosin. On the contrary, the addition of HAP and TCP interfered with the hydrophobic interaction between myosin molecules, and greatly reduced the viscoelasticity of myosin. In summary, calcium with high calcium release rate can improve the physicochemical properties of myosin, HAP and TCP with a very low calcium release rate interfered with the formation of myosin gelation. And it could be concluded that the calcium ions played a leading role in the physicochemical properties of myosin, the more calcium ion that the calcium salt can release, the better physicochemical properties the myosin were. Our work may provide an insight into the phenomenon why different kinds of calcium salts differ from each other on affecting the physicochemical properties of myosin during gel processing.

Physicochemical properties and osteoclastogenesis for three premixed calcium silicate-based sealers post set.

Solubility, pH, ion release, cytotoxicity, and osteoclastogenesis inhibition in bone marrow-derived monocyte macrophages (BMMs) were evaluated in EndoSequence BC Sealer (END), Bio-C Sealer (BC), and Sealer Plus BC (SPBC). pH was determined after immersion of the sealers in deionized water (DW) and Minimum Essential Medium Alpha (α-MEM). Solubility was obtained by mass loss. Ion release was measured by using X-ray fluorescence spectroscopy (XRF). Cytotoxicity was evaluated by MTT assay. Inhibition of osteoclastogenesis was evaluated by tartrate-resistant acid phosphatase (TRAP). Data were analyzed using the t-test, ANOVA and Tukey/Dunnett's post-hoc tests (α = 0.05). END had the highest pH in DW (p < 0.05), and BC, in α-MEM (p < 0.05). Solubility in DW was the lowest for SPBC (p < 0.005). The highest calcium release was observed for BC in DW at 12 h (p < 0.05), and in α-MEM at 12 and 24 h (p < 0.05). The lowest toxicity was detected for END (p < 0.05). BC had the highest inhibitory effect on osteoclasts (p < 0.05). Overall, the highest solubility and pH values were found in DW. However, the calcium silicate-based sealer showed higher solubility than the ISO standards. Calcium release was the highest for BC. END showed the highest cell viability, and BC, the highest osteoclast inhibition.

In Vitro and In Vivo Efficacy of New Composite for Direct Pulp Capping

Objectives To investigate physicochemical properties, dentin bonding, cytotoxicity, and in vivo pulp response of experimental self-adhesive composites tailored to direct pulp capping. Materials and Methods Experimental composites were prepared with beta-tricalcium phosphate and hydroxyapatite nanoparticles adsorbed with simvastatin and glutathione added at 0% (control resin), 1 wt% (Res 1%), and 10 wt% (Res 10%). A commercial light-curable calcium hydroxide (Ca(OH)2) (Ultra-Blend Plus) was used as control material. The physicochemical properties investigated were flexural strength and modulus, calcium release, and degree of conversion. Dentin bonding was assessed by the push-out test. Proliferation and cell counting assays were performed to evaluate in vitro cytotoxicity using fluorescence microscopy. In vivo pulp capping was performed on molars of Wistar rats, which were euthanized after 14 days and evaluated by histological analysis. Results No statistical difference was observed in flexural strength and cell viability (p > 0.05). Res 10% presented higher modulus than control resin and Ca(OH)2. Also, Res 10% attained statistically higher degree of conversion when compared to other experimental composites. Ca(OH)2 showed higher calcium release after 28 and 45 days of storage, with no statistical difference at 45 days to Res 10%. All experimental composites achieved significantly higher bond strength when compared to Ca(OH)2. While no significant difference was observed in the cell proliferation rates, resins at lower concentrations showed higher cell viability. In vivo evaluation of pulp response demonstrated no pulp damage with experimental composites. Conclusions The experimental composite investigated in this study achieved adequate physicochemical properties with minor in vivo pulpal inflammation and proved to be a valuable alternative for direct pulp capping.

Fluoride and calcium release from peppermint-flavored fluoride varnish containing dicalcium-phosphate-dihydrate coated with xylitol

Bakground: Fluoride varnish with high initial fluoride and calcium release can help patients with high-risk caries. Ample quantities of free fluoride and calcium ions in the oral cavity can enhance enamel remineralization. This study aimed to investigate the effect of dicalcium phosphate dihydrate coated with xylitol (DCPD-xylitol), in fluoride varnish, on the release of fluoride and calcium ions in the oral cavity. Materials and methodsDCPD powder with xylitol was synthesized by preparing a 60% xylitol solution and mixed it with DCPD solution. The mixture was stirred for 1 h at room temperature and dried at 80 °C for 18 h to reduce the water content. Then, the powder was used in the formulation of peppermint-flavored fluoride varnish as an active agent. The amounts of fluoride and calcium ion released in deionized water at 37 °C for 6 h were assessed with an ion-selective electrode. The cumulative fluoride and calcium ion release data were analyzed using one-way analysis of variance (ANOVA) and the post hoc Tukey test with α = 0.05. ResultsThe results showed that the addition of DCPD coated with xylitol provided better bioavailability of the ions than DCPD without coating. Peppermint-flavored fluoride varnish (PFFV) with DCPD-xylitol 1% gave the highest fluoride ion release (296.90 mg/L) compared to the varnishes with other xylitol concentrations and the positive control. In contrast, PFFV DCPD-xylitol 5% afforded the highest calcium ion release at 111.20 mg/L. ConclusionsThis study concluded that xylitol affects the bioavailability of free fluoride and calcium ions in varnishes. However, the efficacy of fluoride and calcium uptake in enamel and under different in vitro media conditions requires further investigation.

Biomineralization potential and biological properties of a new tantalum oxide (Ta2O5)\u2013containing calcium silicate cement

ObjectiveThe present study evaluated the biological effects and biomineralization potential of a new tantalum oxide (Ta2O5)–containing material designed for vital pulp therapy or perforation repair (NeoMTA 2), compared to NeoMTA Plus and Bio-C Repair.Material and methodsHuman dental pulp stem cells (hDPSCs) were exposed to different eluates from NeoMTA Plus, NeoMTA 2, and Bio-C Repair. Ion release from each material was determined using inductively coupled plasma-optical emission spectrometry (ICP-MS). The biological experiments performed were MTT assays, apoptosis/necrosis assays, adhesion assays, migration assays, morphology evaluation, and reactive oxygen species (ROS) production analysis. Biomineralization was assessed by Alizarin red S staining. Finally, osteo/odontogenic gene expression was determined by real-time quantitative reverse-transcriptase polymerase chain reaction (RT-qPCR). Data were analyzed using one-way ANOVA followed by Tukey’s multiple comparison test.ResultsNeoMTA 2 displayed a significantly higher calcium release compared to the other materials (p < 0.05). When hDPSCs were cultured in presence of the different material eluates, all groups exhibited similar hDPSC viability and migration rates when compared to untreated cells. Substantial cell attachment and spreading were observed in all materials’ surfaces, without significant differences. hDPSCs treated with NeoMTA 2 displayed an upregulation of ALP, Col1A1, RUNX2 (p < 0.001), ON, and DSPP genes (p < 0.05), and showed the highest mineralization potential compared to other groups (p < 0.001). Finally, the more concentrated eluates from these materials, specially NeoMTA Plus and NeoMTA 2, promoted higher ROS production in hDPSCs compared to Bio-C Repair and control cells (p < 0.001), although these ROS levels did not result in increased cell death.ConclusionsThe new tantalum oxide (Ta2O5)–containing material shows an adequate cytocompatibility and the ability to promote biomineralization without using chemical osteogenic inducers, showing great potential as a new material for vital pulp therapy.Clinical relevanceNeoMTA 2 seems to be a promising material for vital pulp therapy. Further studies considering its biocompatibility and biomineralization potential are necessary.

Bond strength efficiency of a high fluoride and calcium release self-adhesive resin cement: A comparative in vitro study

Aim: To clarify the bond strength of Theracem in comparison to other types of adhesive material, in addition to testing the adhesive remnant index (ARI). Material and Methods: A hundred extracted human premolars were collected for orthodontic purposes. Teeth were stored in 1% Chloramine-T trihydrate as bacteriostatic/bactericidal solution for one week; then, they were transmitted into distilled water. The buccal surface of the studied teeth was kept under surveillance and mounted in acrylic block. Siamese metal pre-adjusted premolar brackets were fixed on the buccal surface using three adhesive cements: Bisco ORTHO, GC Fuji ORTHO LC (Light Cure) and Theracem. The teeth were randomly divided into five groups of 20 specimens each. Group 1 (G1) used 37% phosphoric acid gel, Bisco primer, and Bisco adhesive. Group 2 (G2) used GC Fuji ORTHO LC (Light Cure) without etching. Group 3 (G3) used GC Fuji ORTHO LC (Light Cure) with etching. Group 4 (G4) used Theracem without etching. Group 5 (G5) used Theracem with etching. All the tested specimens were kept at 370°C in a distilled water bath for 24 h. Shear bond strength (SBS) was conducted using a universal microcomputer-controlled electronic test machine. Then, specimens’ surfaces were assessed under a stereomicroscope with a 10× magnification to examine the orthodontics adhesive residue’s buccal surface and scored using ARI. Results: The G4 exhibited the lowest mean bond strength value (M = 11.24, SD = 3.52), whereas G3 yielded the highest bond strength value (M = 25.02, SD = 3.41). The variance analysis revealed F = 61.71, indicating a significant difference among the bond strength values (P < .001). Tukey HSD post hoc testing demonstrated a significant difference in bond strength among groups, except G2 with G1 and G3. Kruskal–Wallis test showed statistically significant differences among all groups (P < .001). On comparison, the least adhesives that remained on the tooth surface were in G4 and G5. Conclusion: Theracem bonding system provides many advantages, as there is no need for an acid-etching step, it is easy to manipulate, and it provides a very suitable S.B.S. with no enamel detachment during debonding. Also, scores 0 and 1 in the ARI test lead to a decrease in enamel damage.

A New Calcium Silicate-Based Root Canal Dressing: Physical and Chemical Properties, Cytotoxicity and Dentinal Tubule Penetration.

The aims of this study were to evaluate the physical and chemical properties, cytotoxicity and dentinal tubule penetration of a new calcium silicate-based root canal dressing. For pH and calcium ion release evaluation (1, 24, 72 and 168 h) were used a pH meter and colorimetric spectrophotometer, respectively. Radiopacity evaluation followed the ISO 6876:2012. Cytotoxicity was evaluated by the percentage of cell viability using MTT assay. Illustrative images of dentinal tubule penetration were obtained using confocal laser scanning microscopy (CLSM). Data from pH and calcium ion release were statistically analyzed by two-way analysis of variance and Tukey test. Radiopacity was analyzed using the Student t-test. The statistical tests for cytotoxicity results were the one-way analysis of variance and Tukey test. Both materials showed alkaline pH in all experimental times. The pH values for calcium hydroxide paste were higher than bioceramic paste at 1, 24, and 72 h (p<0.05). The calcium ion release of bioceramic was lower than the calcium hydroxide paste only at 24 h (p<0.05). The bioceramic was more radiopaque than the calcium hydroxide paste (p<0.05). Bioceramic paste presented a dose and time-dependent cytotoxic effect after MTT assay. CLSM images showed absence of tubule penetration for both pastes. The new calcium silicate-based canal dressing presented alkaline pH, high calcium release, and acceptable radiopacity. Bio C Temp showed a dose and time-dependent cytotoxic and absence of dentinal tubule penetration.

PHYSICOCHEMICAL CHARACTERIZATION: COMPARATIVE EVALUATION OF ALLOGRAFT BIOMATERIALS AND AUTOGENOUS BONE

Objectives: bone substitutes used in oral surgery include allografts, xenografts and synthetic materials that are frequently used to compensate bone loss or to reinforce repaired bone by encouraging new bone ingrowth into the defect site. The aim of this study was to evaluate a number ofphysical and chemical properties in a variety of allografts biomaterials used in oral surgery and to compare them with those of autogenous bone. Materials and methods: autogenous bone andfive different allograft biomaterials were studied by high-resolution X-ray diffractometry, atomic absorption spectrometry, laser diffraction, and checked for their chemical composition, calcium release concentration, crystallinity and granulation size. Results: the highest calcium release concentration was 24.94 mg/gforPuros® and the lowest one was 4.05 mg/gfor OsteoSponge® compared to 20.15 mg/g to natural bone. The range ofparticles size, in term of median size D50, varied between 394.24 pm for DIZG Spongiosa® and 902.41 pm for OsteoSponge®, compared to 282.1 pm for natural bone. Bone and Puros® displayed a hexagonal shape as bone except and OsteoSponge® which showed a triclinic shape and all the rest showed monoclinic shape. Conclusion: a bone substitute of choice depends largely on its clinical application that is associated to its biological and mechanical performance. These morphological differences between biomaterials greatly influence their in-vivo behavior of biomaterials. Significant differences were detected in terms of calcium concentration, particles size, and crystallinity.

Abstract 1692: Role of snail in cancer-bone microenvironment interactions

Abstract Prostate Cancer (PCa) is the second leading cause of cancer death in American men and African Americans are twice as likely to get PCa as their Caucasian counterparts. As with most forms of cancer, PCa patients’ mortality is mainly attributed to complications caused by metastasis of the disease to organs critical for survival such as bone. As such, it is important to understand cancer-bone microenvironment interactions in order to develop therapeutics that will slow or halt the process of cancer metastasis. It is also known that African Americans have a higher bone mineral density compared to any other race. Snail1 is a zinc-finger transcription factor that induces epithelial-mesenchymal transition (EMT) which is associated with cell migration and metastasis in cancer cells. In preliminary studies, cancer cells co-cultured with bovine bone discs led to increased calcium release that was higher in cancer cells overexpressing Snail, as well as in bone discs of higher density. We hypothesized that cancer cell-bone interactions would promote higher calcium release from bone by cancer cells overexpressing Snail, which would lead to increased paracrine cell migration. For this study, we utilized prostate (ARCaP) or breast (MCF-7) cancer cells stably overexpressing Snail as well as prostate (C4-2) cancer cells with stable Snail knockdown. Cancer cells were co-cultured with bovine bone disc or Hydroxyapatite (HA; inorganic component of bone) of different densities to represent the African American vs Caucasian bone ratio. The conditioned media was then used for to assay calcium levels, test paracrine cell viability and migration assays using C4-2 parental cells. We observed that calcium levels were elevated in conditioned media from cancer cell-bone co-cultures, compared to media alone or media plus bone, and this could be antagonized by EGTA, a calcium chelator. It was increased with higher bone density as well as with bone co-cultured with MCF-7-Snail, ARCaP-Snail and C4-2 cancer cells as compared to MCF-7 Neo, ARCaP-Neo or C4-2 with Snail knockdown. When we utilized the conditioned media for a paracrine cell viability assay, there was no significant differences. However, C4-2 cancer-bone co-culture conditioned media increased paracrine cell migration which was decreased by Snail knockdown as well as lower bone density. Hence Snail expressing PCa cells co-cultured with HA led to increased paracrine cell migration. We are currently studying the signaling mechanism(s) involved in this cancer-bone interactions. In conclusion, our study shows that Snail can mediate cancer-bone microenvironment interactions that can possibly promote increased cell migration towards bone of high mineral density such as is found in African Americans. GRANT SUPPORT: 1P20MD002285 Citation Format: Veronica M. Henderson, Liza J. Burton, Simone M. Howard, Valerie A. Odero-Marah. Role of snail in cancer-bone microenvironment interactions. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1692.

Evaluation of the pH, calcium release and antibacterial activity of MTA Fillapex

OBJECTIVE: This study evaluated, in several analysis periods, pH and calcium release and antibacterial activity provided by MTA Fillapex sealer compared to Sealapex and AH Plus sealers. MATERIAL AND METHOD: Polyethylene tubes were filled with a sealer and immersed in distilled water. After 24 hours, 14 and 28 days, pH and calcium release by endodontic sealers were evaluated directly in water which the tubes were stored. Sealers antibacterial activity was evaluated against Enterococcus faecalis and Staphylococcus aureus by means of agar diffusion test. All data were submitted to ANOVA and Tukey tests (α=0.05). RESULT: In all periods evaluated, Sealapex had the highest pH value (p&lt;0.05) in comparison to other sealers and MTA Fillapex provided higher pH values than AH Plus (p&lt;0.05). In 14-days period, MTA Fillapex had greater calcium release value than Sealapex (p&lt;0.05). In 28-days period, Sealapex provided higher calcium release than MTA Fillapex (p&lt;0.05). In all periods, AH Plus provided lower calcium release than other sealers (p&lt;0.05). In relation to E. faecalis, there were no differences among the sealers, in relation to antibacterial activity (p&gt;0.05). In relation to S. aureus, Sealapex presented better antibacterial effectiveness than the MTA Fillapex and AH Plus (p&lt;0.05), which were similar each other (p&gt;0.05). CONCLUSION: In final evaluation period, pH values and calcium release provided by MTA Fillapex were lower than provided by Sealapex and higher than provided by AH Plus. The MTA Fillapex antimicrobial action was similar to other endodontic sealers.

Biointeractivity-related versus chemi/physisorption-related apatite precursor-forming ability of current root end filling materials

Commercial root end filling materials, namely two zinc oxide eugenol-based cements [intermediate restorative material (IRM), Superseal], a glass ionomer cement (Vitrebond) and three calcium-silicate mineral trioxide aggregate (MTA)-based cements (ProRoot MTA, MTA Angelus, and Tech Biosealer root end), were examined for their ability to: (a) release calcium (Ca(2+) ) and hydroxyl (OH(-) ) ions (biointeractivity) and (b) form apatite (Ap) and/or calcium phosphate (CaP) precursors. Materials were immersed in Hank's balanced salt solution (HBSS) for 1-28 days. Ca(2+) and OH(-) release were measured by ion selective probes, surface analysis was performed by environmental scanning electron microscopy/energy dispersive X-ray analysis, micro-Raman, and Fourier transform infrared spectroscopy. IRM and Superseal released small quantities of Ca(2+) and no OH(-) ions. Uneven sparse nonapatitic Ca-poor amorphous CaP (ACP) deposits were observed after 24 h soaking. Vitrebond did not release either Ca(2+) or OH(-) ions, but uneven nonapatitic Ca-poor CaP deposits were detected after 7 days soaking. ProRoot MTA, MTA Angelus, and Tech Biosealer root end released significant amounts of Ca(2+) and OH(-) ions throughout the experiment. After 1 day soaking, nanospherulites of CaP deposits formed by amorphous calcium/magnesium phosphate (ACP) Ap precursors were detected. A more mature ACP phase was present on ProRoot MTA and on Tech Biosealer root end at all times. In conclusion, zinc oxide and glass ionomer cements had little or no ability to release mineralizing ions: they simply act as substrates for the possible chemical bonding/adsorption of environmental ions and precipitation of nonapatitic Ca-poor ACP deposits. On the contrary, calcium-silicate cements showed a high calcium release and basifying effect and generally a pronounced formation of more mature ACP apatitic precursors correlated with their higher ion-releasing ability.

The effects of incorporation of silver-zeolite on selected properties of mineral trioxide aggregate

The purpose of this study was to evaluate some physical and chemical properties of MTA incorporated with antibacterial silver zeolite (SZ). 0%, 0.2% or 2% mass fraction of SZ was added to MTA powder. The amounts of calcium released from the specimen in deionized water were measured with an atomic absorption spectrophotometer. The setting times of the samples were evaluated using Gilmore-type needles. For solubility and water absorption tests, the samples were placed in a cylindrical polystyrene-sealed container. At 7 days, the samples were removed from solutions and blotted dry for solubility and water absorption test. The highest calcium release was detected in 2% SZ MTA at 24 h. The addition of 2% SZ to MTA reduced the setting time statistically (p<0.05). 2% SZ MTA was significantly more soluble than MTA and 0.2 % SZ MTA (p<0.05). Further research is needed prior to clinical use of MTA with incorporated SZ.