Zoledronate Promotes Peri-Implant Osteogenesis in Diabetic Osteoporosis by the AMPK Pathway.

Together with diabetic osteoporosis (DOP), diabetes patients experience poor peri-implant osteogenesis following implantation for dentition defects. Zoledronate (ZOL) is widely used to treat osteoporosis clinically. To evaluate the mechanism of ZOL for the treatment of DOP, experiments with DOP rats and high glucose-grown MC3T3-E1 cells were used. The DOP rats treated with ZOL and/or ZOL implants underwent a 4-week implant-healing interval, and then microcomputed tomography, biomechanical testing, and immunohistochemical staining were performed to elucidate the mechanism. In addition, MC3T3-E1 cells were maintained in an osteogenic medium with or without ZOL to confirm the mechanism. The cell migration, cellular actin content, and osteogenic differentiation were evaluated by a cell activity assay, a cell migration assay, as well as alkaline phosphatase, alizarin red S, and immunofluorescence staining. The mRNA and protein expression of adenosine monophosphate-activated protein kinase (AMPK), phosphorylated AMPK (p-AMPK), osteoprotegerin (OPG), receptor activator of nuclear factor kappa B ligand (RANKL), bone morphogenetic protein 2 (BMP2), and collagen type I (Col-I) were detected using real-time quantitative PCRs and western blot assays, respectively. In the DOP rats, ZOL markedly improved osteogenesis, enhanced bone strength and increased the expression of AMPK, p-AMPK, and Col-I in peri-implant bones. The in vitro findings showed that ZOL reversed the high glucose-induced inhibition of osteogenesis via the AMPK signaling pathway. In conclusion, the ability of ZOL to promote osteogenesis in DOP by targeting AMPK signaling suggests that therapy with ZOL, particularly simultaneous local and systemic administration, may be a unique approach for future implant repair in diabetes patients.

Osteogenic and long-term antibacterial properties of Sr/Ag-containing TiO2 microporous coating in vitro and in vivo.

Bacterial infection and poor osseointegration are two critical issues that need to be solved for long-term use of titanium implants. As such, Sr/Ag-containing TiO2 microporous coatings were prepared on a Ti alloy surface in the current study via a single-step microarc oxidation technique. The coatings showed both good cytocompatibility in vitro and biosafety in vivo. Sr/Ag incorporation brought no significant change in the surface micromorphology and physicochemical properties, but endowed the coating with strong osteogenic activity and long-term antibacterial capability in vitro. Furthermore, the osteogenic and antibacterial capability of the coating was also confirmed in vivo. In a rat osseointegration model, new bone formation, implant-bone contact, removal torque and bone mineralization were all significantly increased in the M-Sr/Ag group when compared with those in group M, although they were slightly lower than those in group M-Sr. In a periimplantitis model, no rats suffered infection in the M-Sr/Ag group after 3 months of osseointegration and 5 weeks of bacterial inoculation period, when compared to 100% and 75% infection rates in M and M-Sr groups, respectively. In addition, active bone remodeling and many mesenchymal cells were observed in the M-Sr group, suggesting good bone regeneration potential in Sr-containing coatings in the case of controlled periimplantitis. Overall, the Sr/Ag-containing TiO2 microporous coating is valuable for preventing periimplantitis and improving implant reosseointegration, and is therefore promising for long-term and high quality use of titanium implants.

The effect of strontium content on physicochemical and osteogenic property of Sr/Ag-containing TiO2 microporous coatings.

Strontium (Sr) is the most common element introduced into TiO2 coatings to strengthen the osteogenic property of titanium implants. However, the optimal Sr content and its effect on osteogenic and physicochemical properties of the coatings need to be clarified. In the current study, TiO2 microporous coatings with different contents of Sr (9.64-21.25 wt %) and silver (Ag) (0.38-0.75 wt %) were prepared via micro-arc oxidation technique. Sr contents did not change physicochemical properties of the coatings, including surface microstructure, micropore size and distribution, phase composition, roughness and hydrophilicity. Meanwhile, higher Sr contents (18.23-21.25 wt %) improved cytocompatibility, proliferation and alkaline phosphatase (ALP) activity of preosteoblasts, even the coatings underwent 30 days' PBS immersion. Furthermore, higher Sr contents facilitated preosteoblast growth and spreading, which are essential for their proliferation and osteogenic differentiation. Therefore, it is promising to incorporate higher Sr content (18.23-21.25 wt %) within TiO2 microporous coatings to improve their osteogenic capability.

Angiogenic property of cobalt and calcium-phosphorus doped coating on titanium surfaces in vitro / 口腔疾病防治

Objective@# To investigate the effect of cobalt (Co) and calcium-phosphate (Ca/P) doped coating on titanium surfaces and their angiogenic effect.@*Methods @# Microarc oxidation (MAO) was used to prepare Co-Ca/P-doped and Co-doped coatings. Titanium (Ti) sheet without MAO treatment was used as control. Scanning electron microscopy (SEM) was used to observe the surface micromorphology of the coatings. Energy dispersive spectrometry (EDS) was also applied to detect the doped chemicals and their contents. Standard soaking solutions of these coatings were prepared using an endothelial cell medium (ECM) solution for subsequent angiogenesis experiments. Human umbilical vein endothelial cells (HUVECs) were cultured on Matrigel with ECM soaking solutions for 4 h and 8 h. The microvessels were observed under a microscope, and the number of microtubules and their interconnecting nodes were analyzed with Image J software. @*Results@# Co doped and Co-Ca/P-doped coatings were successfully prepared by MAO, which was demonstrated by both SEM observation and EDS analysis. SEM observation showed that irregular crystals of the above chemicals were present on both Co and Co-Ca/P-doped coatings, commonly with a diameter <2 μm. However, more crystals were observed on the Co-Ca/P coatings than on the Co coating, and the distribution of the crystals was more homogenous on the Co-Ca/P coatings. However, only polishing scratches were observed on the Ti sample surface. EDS analysis indicated that in contrast to only Co in the Co coating, Co, Ca and P were doped within the Co-Ca/P coating, and none of the three elements were observed on the Ti plate surface. The number of vascular rings and nodes formed by HUVECs in the extract of the Co-Ca/P group was significantly higher than that of the Co group (P<0.05), and the angiogenic effect of these two components was significantly better than that of the Ti group (P<0.05). @*Conclusion@#The Co-Ca/P coating exhibits good angiogenic properties in vitro and is valuable for the development of new titanium implants with high surface bioactivity.

Classification and research progress of implant surface antimicrobial techniques.

Due to the good biocompatibility and ideal mechanical property, titanium implants have been widely used in dental clinic and orthopedic surgery. However, bacteria induced infection can cause per-implant inflammation and decrease the success rate of implant surgery. Therefore, developing antimicrobial techniques is essential to successful application of titanium implants. Many surface antimicrobial techniques, including antimicrobial coating and surface modifications, have been explored and they always exert antimicrobial effect by reducing bacterial adhesion, inhibiting their metabolism, or destructing cell structure. In this paper, different surface antimicrobial techniques and their recent research progress are reviewed to provide a brief insight on this area.

Osteogenic capability of strontium and icariin-loaded TiO2 nanotube coatings in vitro and in osteoporotic rats.

Titanium (Ti) and Ti alloys are widely used biomaterials, but they lack osteogenic capability for rapid bone integration. To improve osseointegration of Ti implants, TiO2 nanotubes were prepared using the anodizing oxidation technique, and strontium (Sr) combined with icariin (ICA) was loaded on TiO2 nanotube coatings. Cell adhesion and proliferation of MC3T3-E1 cells, alkaline phosphatase (ALP) activity, mineralization of extracellular matrix, and bone formation around titanium implants in ovariectomized rats, were examined separately. The results showed that compared with pure Ti, TiO2 and Sr-loaded TiO2 coatings, the coatings loaded with both Sr and ICA showed better effect on cell adhesion and proliferation, higher ALP activity and more red-stained mineralized nodules. Furthermore, more bone was formed around implants loaded with both Sr and ICA in osteoporotic rats. Therefore, coating with Sr and ICA is valuable for clinical application to strengthen the osseointegration of titanium implants, especially in osteoporotic patients.

Evaluation of osteogenic and antibacterial properties of strontium/silver-containing porous TiO2 coatings prepared by micro-arc oxidation.

Ti and Ti alloys are bioinert materials and two frequent problems associated with them are bacterial infection and lack of osteogenic potential for rapid bone integration. To overcome the problems, the present study incorporated strontium (Sr) and silver (Ag) simultaneously into porous TiO2 coatings through a single-step technique, micro-arc oxidation (MAO). Incorporation of Sr and Ag brought no significant changes to coating micromorphology and physicochemical properties, but endowed TiO2 coatings with both strong antibacterial activity and osteogenic ability. Antibacterial activity increased with Ag contents in the coatings. When Ag content reached 0.58 wt%, the coating showed both excellent short-term (100.0%) and long-term (77.6%) antibacterial activities. Sr/Ag-containing coatings with 18.23 wt% Sr and 0.58 wt% Ag also presented good cytocompatibility for preosteoblast adhesion and proliferation, and promoted preosteoblast osteogenic differentiation both short-termly and long-termly. However, higher Ag content (1.29 wt%) showed toxic effects to preosteoblasts. In summary, MAO is a simple and effective way to incorporate Sr and Ag into porous TiO2 coatings and Sr/Ag-containing TiO2 coating with 18.5 wt% Sr and 0.58 wt% Ag has both good osteogenic activity and strong antibacterial capability short-termly and long-termly. Therefore, such coatings are valuable for clinical application to strengthen osseointegration and long-term high quality use of titanum implants.

[Zoledronate regulates osteoclast differentiation and bone resorption in high glucose through p38 MAPK pathway].

OBJECTIVE: To investigate the effect of zoledronate (ZOL) on osteoclast differentiation and bone resorption under high glucose, and the regulation mechanism of p38 mitogen activated kinase (p38 MAPK) signaling pathway in this process. METHODS: RAW264.7 cells were divided into four groups: low group, high group, low+ZOL group and high+ZOL group after induced into osteoclasts. Cell proliferation activity was determined by MTT assay. The migration of RAW264.7 cells were examined Optical microscopy. Immunofluorescence microscopy was used to observe the cytoskeleton and sealing zones of osteoclasts. After adding group 5: high + ZOL + SB203580 group, trap staining was used to identify the number of positive osteoclasts in each group. The number and area of resorption lacunae were observed by SEM. The mRNA and protein expression of osteoclast related factors were detected by real-time PCR and Western blotting. RESULTS: The cells in the 5 groups showed similar proliferative activity. High glucose promoted the migration of RAW264.7 cells (P < 0.05), inhibited the clarity of cytoskeleton and the formation of sealing zones in the osteoclasts. Exposure to high glucose significantly lowered the expressions of p38 MAPK, p-p38 MAPK, NFATc1, CTSK and TRAP, and inhibited osteoclast differentiation and bone absorption (P < 0.05). Treatment with ZOL obviously suppressed the migration ability of RAW264.7 cells, further reduced the clarity of the cytoskeleton, inhibited the formation of sealing zones of the osteoclasts, lowered the expressions of p38 MAPK, p-p38 MAPK, NFATc1, CTSK, and TRAP (P < 0.05), and inhibited osteoclast differentiation and bone absorption. Treatment with SB203580 obviously inhibited osteoclast differentiation and bone resorption and the expressions of P38 MAPK, p-p38 MAPK, NFATc1, CTSK and TRAP (P < 0.05). CONCLUSIONS: High glucose inhibits osteoclast differentiation and bone resorption. ZOL inhibits osteoclast differentiation and bone resorption in high-glucose conditions by regulating p38 MAPK pathway, which can be a new pathway for ZOL to regulate diabetic osteoporosis.

Effectiveness of strontium-doped brushite, bovine-derived hydroxyapatite and synthetic hydroxyapatite in rabbit sinus augmentation with simultaneous implant installation.

Various bone substitutes have been applied in sinus augmentation (SA) to overcome insufficient bone height at the posterior maxilla region caused by pneumatized sinus and severe alveolar bone resorption after teeth loss. However, their effectiveness in SA needs to be further elucidated. In this study, strontium-doped brushite (Sr-DCPD), a new bone substitute, together with bovine-derived hydroxyapatite (bHA) and synthetic hydroxyapatite (sHA) was used in rabbit maxillary SA with simultaneous implant installation. The sinus space-keeping capacity, resorption rate, osteoconductivity, and mechanical properties of regenerated bone, were evaluated by micro-computed tomography (CT), histological analysis, and mechanical testing. Sr-DCPD exhibited the best osteoconductivity and new bone formation (<4 weeks), but its final bone regeneration and removal torque of implants at week 12 were the lowest, mainly due to its poor space-keeping capacity and fast resorption. bHA exhibited the best space-keeping capacity and slowest resorption rate, but relative lower final bone volume and mechanical properties, while sHA showed good space-keeping capacity, slower resorption rate, and the best final bone formation and mechanical properties. sHA was most effective for SA and bHA was also an acceptable bone substitute; however, Sr-DCPD was least effective and not suitable in SA by itself.

CaMKII(δ) regulates osteoclastogenesis through ERK, JNK, and p38 MAPKs and CREB signalling pathway.

Calcium/calmodulin-dependent protein kinases (CaMKs) are a group of important molecules mediating calcium signal transmission and have been proved to participate in osteoclastogenesis regulation. CaMKII, a subtype of CaMKs is expressed during osteoclast differentiation, but its role in osteoclastogenesis regulation remains controversial. In the present study, we identified that both mRNA and protein levels of CaMKII (δ) were upregulated in a time-dependent manner during osteoclast differentiation. CaMKII (δ) gene silencing significantly inhibited osteoclast formation, bone resorption, and expression of osteoclast-related genes, including nuclear factor of activated T cells c1 (NFATc1), tartrate-resistant acid phosphatase (TRAP), and c-Src. Furthermore, CaMKII (δ) gene silencing downregulated phosphorylation of mitogen-activated protein kinases (MAPKs), including JNK, ERK, and p38, which were transiently activated by RANKL. Specific inhibitors of ERK, JNK, and p38 also markedly inhibited expression of osteoclast-related genes, osteoclast formation, and bone resorption like CaMKII (δ) gene silencing. Additionally, CaMKII (δ) gene silencing also suppressed RANKL-triggered CREB phosphorylation. Collectively, these data demonstrate the important role of CaMKII (δ) in osteoclastogenesis regulation through JNK, ERK, and p38 MAPKs and CREB pathway.

Zoledronate and high glucose levels influence osteoclast differentiation and bone absorption via the AMPK pathway.

Bisphosphonates, the main drugs to treat osteoporosis, have been shown to protect against bone loss in diabetic osteoporosis. However, the effects of the bisphosphonate zoledronate (ZOL) on osteoclast differentiation and function in a high glucose environment as well as the involvement of the adenosine activated protein kinase (AMPK) pathway remain unclear. In the current study, RAW264.7 cells were induced into osteoclasts, divided into low glucose, high glucose, low glucose + ZOL, and high glucose + ZOL groups, which were tested for cell proliferation, cell migration, integrity of the osteoclast sealing zone, osteoclast differentiation, bone absorption, and protein and mRNA expression of genes in the AMPK pathway. We demonstrated that high glucose promoted the expression of AMPK, p-AMPK, while inhibited nuclear factor of activated T cells 1 (NFATc1), spleen tyrosine kinase (SYK), cathepsin K (CTSK), and tartrate-resistant acid phosphatase (TRAP), which influenced osteoclast differentiation and bone absorption. Upon addition of ZOL to high glucose, the expression of AMPK, p-AMPK increased and the expression of NFATc1, SYK, CTSK, TRAP decreased, while osteoclast differentiation and bone absorption were further inhibited. Further more, when added Compound C (AMPK antagonist), we found the expression of AMPK, p-AMPK, decreased, whereas NFATc1, SYK, and TRAP increased. In contrast, AMPK and p-AMPK increased and NFATc1, SYK, CTSK and TRAP decreased upon addition of AICAR, an AMPK agonist. In conclusion, the results suggest AMPK has potential as a new target for the treatment of osteoporosis, the high glucose environment promoted RAW264.7 cell migration, but suppressed osteoclast differentiation and bone absorption, and ZOL suppressed osteoclast migration, differentiation, and bone absorption via the AMPK pathway.

[Expression profiles of CaMKIIγ during osteoclast differentiation].

OBJECTIVE: To study the expression profiles and the role of Ca2+/calmodulin-dependent protein kinase IIγ (CaMKIIγ) during osteoclast differentiation.
 Methods: Mouse RAW264.7 cells were induced for osteoclastogenesis with 50 ng/mL receptor activator of nuclear factor-κB ligand (RANKL) and the cells were harvested at 0, 1, 3 and 5 days after induction. Tartrate-resistant acid phosphotase staining was performed to verify osteoclasts formation. RT-PCR, Western blot and immunofluorescent cytochemistry were used to detect the CaMKIIγ gene expression during osteoclastogenesis.
 Results: The osteoclasts were formed at day 3 under RANKL induction and more osteoclasts were observed at day 5. At day 0, 1, 3 and 5, the relative level of CaMKIIγ mRNA were (1.067±0.179), (1.840±0.070), (9.493±0.453) and (30.767±0.573), respectively, and the relative protein level were (0.454±0.065), (0.613±0.021), (0.858±0.019) and (0.980±0.023), respectively. CaMKIIγ expression was increased in a time-dependent manner except relative protein level at day 1 (P<0.01), which showed no significant difference at day 0 (P>0.05). Immunofluorescence assay showed that CaMKIIγ protein was also increased with differentiation of osteoclasts.
 Conclusion: The CaMKIIγ expression was increased in a time-depended manner during osteoclast differentiation and it might play a vital role during osteoclastogenesis.

[Multiple pulp stones: report of a case and literature review].

Pulp stones were denaturation of pulp tissue, which were usually found in the pulp chamber. Generally, they were associated with caries and pulposis, and the occurrence of pulp stone increased with age. Pulp stones were frequently found by radiographic examination, and appeared as radiopaque lesions which were round or ovoid in shape. We reported an unusual case of multiple pulp stones with normal clinical crowns in a young female patient and analyzed the possible etiology.

[Effect of thalidomide on development of bisphosphonate-related osteonecrosis of the jaws in rats].

OBJECTIVE: To investigate the effect of thalidomide on the development of bisphosphonate-related osteonecrosis of the jaws (BRONJ). METHODS: Thirty-six rats were randomly divided into groups A, B and C, and treated with saline, zoledronate and zoledronate plus thalidomide, respectively. Three weeks later, the left maxillary first molars of the rats were extracted. Four and eight weeks after tooth extraction, samples were harvested for evaluation of osteonecrosis of the jaws, microvessel density, and cell apoptosis. RESULTS: At both of the time points, no exposed dead bone was observed at the extraction socket areas in the rats except for some small fistulas in groups B and C. Histological examination confirmed the absence of dead bone in group A, whereas small areas of dead bone were observed around the extraction socket in groups B and C. Compared with those in group A, the percentage of empty lacunae and the area of dead bone were significantly increased (P<0.01), whereas bone lacunae density was significantly decreased (P<0.01) in groups B and C at both time points. Microvessel density in groups B and C were also significantly decreased (P<0.01) by 25.87% and 55.27% at week 4, and by 45.62% and 72.84% at week 8, respectively; the apoptotic cells in groups B and C increased by 54.80% and 87.89% at week 4 (P<0.01), and by 208.08% and 250.58% at week 8 (P<0.01), respectively. CONCLUSION: Thalidomide can aggravate zoledronate-induced early-stage BRONJ, and their osteonecrosis-inducing effect of the jaw may be attributed, at least partly, to the inhibition of angiogenesis.

Zinc ion implantation­deposition technique improves the osteoblast biocompatibility of titanium surfaces.

The plasma immersion ion implantation and deposition (PIIID) technique was used to implant zinc (Zn) ions into smooth surfaces of pure titanium (Ti) disks for investigation of tooth implant surface modification. The aim of the present study was to evaluate the surface structure and chemical composition of a modified Ti surface following Zn ion implantation and deposition and to examine the effect of such modification on osteoblast biocompatibility. Using the PIIID technique, Zn ions were deposited onto the smooth surface of pure Ti disks. The physical structure and chemical composition of the modified surface layers were characterized by scanning electron microscopy (SEM) and X­ray photoelectron spectroscopy (XPS), respectively. In vitro culture assays using the MG­63 bone cell line were performed to determine the effects of Zn­modified Ti surfaces following PIIID on cellular function. Acridine orange staining was used to detect cell attachment to the surfaces and cell cycle analysis was performed using flow cytometry. SEM revealed a rough 'honeycomb' structure on the Zn­modified Ti surfaces following PIIID processing and XPS data indicated that Zn and oxygen concentrations in the modified Ti surfaces increased with PIIID processing time. SEM also revealed significantly greater MG­63 cell growth on Zn­modified Ti surfaces than on pure Ti surfaces (P<0.05). Flow cytometric analysis revealed increasing percentages of MG­63 cells in S phase with increasing Zn implantation and deposition, suggesting that MG­63 apoptosis was inhibited and MG­63 proliferation was promoted on Zn­PIIID­Ti surfaces. The present results suggest that modification with Zn­PIIID may be used to improve the osteoblast biocompatibility of Ti implant surfaces.

Strontium coating by electrochemical deposition improves implant osseointegration in osteopenic models.

Osteopenia, a preclinical state of osteoporosis, restricts the application of adult orthodontic implant anchorage and tooth implantation. Strontium (Sr) is able to promote bone formation and inhibit bone absorption. The aim of the present study was to evaluate a new method for improving the success rate of dental implantation. In this study, an electrochemical deposition (ECD) method was used to prepare a Sr coating on a titanium implant. The coating composition was investigated by energy dispersive X-ray spectroscopy and X-ray diffraction, and the surface morphology of the coating was studied using scanning electron microscopy. A total of 24 Sprague-Dawley rats received bilateral ovariectomy (OVX) and an additional 12 rats underwent a sham surgery. All rats were then implanted in the bilateral tibiae with titanium mini-implants with or without a Sr coating. The results of histological examination and a fluorescence double labeling assay showed strong new bone formation with a wider zone between the double labels, a higher rate of bone mineralization and better osseointegration in the OVX rats that received Sr-coated implants compared with the OVX rats that received uncoated implants. The study indicates that Sr coatings are easily applied by an ECD method, and that Sr coatings have a promoting effect on implant osseointegration in animals with osteopenia.

Low-magnitude high-frequency loading, by whole-body vibration, accelerates early implant osseointegration in ovariectomized rats.

Osteoporosis deteriorates jaw bone quality and may compromise early implant osseointegration and early implant loading. The influence of low­magnitude, high­frequency (LMHF) vibration on peri­implant bone healing and implant integration in osteoporotic bones remains poorly understood. LMHF loading via whole­body vibration (WBV) for 8 weeks has previously been demonstrated to significantly enhance bone­to­implant contact, peri­implant bone fraction and implant mechanical properties in osteoporotic rats. In the present study, LMHF loading by WBV was performed in osteoporotic rats, with a loading duration of 4 weeks during the early stages of bone healing. The results indicated that 4­week LMHF loading by WBV partly reversed the negative effects of osteoporosis and accelerated early peri­implant osseointegration in ovariectomized rats.

[Zoledronate inhibits TRPV5 and NFATc1 expression during differentiation of osteoclasts].

OBJECTIVE: To explore the effect of zoledronate (ZOL) on osteoclast differentiation and expressions of transient receptor potential vanilloid 5 channel (TRPV5) and nuclear factor of activated T-cells cytoplasmic 1 (NFATc1). METHODS: RAW264.7 cells were divided into two groups for treatment with RANKL for 5 days (group A) or with additional ZOL treatment in the last 2 days of RANKL treatment (group B). Osteoclastogenesis of the cells and the mRNA and protein expressions of TRPV5 and NFATc1 after the treatments were examined. RESULTS: In group B, the number of newly generated osteoclasts (≥ 3 nuclei), number and size of dentin resorption lacunaes were 29.0 ± 2.4, 24.8 ± 1.1, and 2 030.0 ± 165.7 µm², respectively, which were significantly lower than those in group A (56.5 ± 4.5, 49.3 ± 0.9, and 3 946.7 ± 367.5 µm², respectively, P<0.01). Fluorescent intensity of TRPV5 and NFATc1 were also significantly decreased in group B (P<0.01). Compared with those in group A, TRPV5 mRNA and protein expressions in group B were down-regulated by 50.4% and 37.8%, and those of NFATc1 by 68.0% and 48.4%, respectively (P<0.01). CONCLUSION: ZOL can significantly inhibit osteoclastogenesis and bone resorption, which may be attributed, at least partly, to ZOL-induced inhibition of TRPV5 and NFATc1 expressions.

[The rescue effect of RANKL on zoledronate induced acid inhibition of osteoclastogenesis and gene expression of NF-kappaB p50 and c-Jun].

In this study, the rescue effect of receptor activator for nuclear factor-kappaB ligand (RANKL) on zoledronate acid (ZOL) induced inhibition of osteoclastogenesis and gene expression of NF-kappaB p50 and c-Jun was investigated. Mice calvarial osteoblasts (OBs) were harvested and co-cultured with RAW264.7 cells and the cells were divided into 4 groups and received treatment with ZOL and RANKL, either single or combined. The formation of multi-nucleated osteoclast (OC) was examined and gene expression of NF-kappaB p50 and c-Jun was detected. Group B (ZOL) showed least multi-nucleated OC and resorption lacunae among the 4 groups (P < 0.05 or P < 0.01) and it was followed by group C (ZOL+RANKL). Group D (RANKL) showed highest OC and resorption lacunae while it was similar to Group A (control) (P > 0.05). Gene expression of NF-kappaB p50 and c-Jun was the lowest in group B (P < 0.05 or P < 0.01) among the four groups and was significantly increased in group C when compared with group B (P < 0.05). Group A and D showed highest gene expression and they were similar to each other (P > 0.05). This study suggest that RANKL might partly rescue ZOL induced inhibition of osteoclastogenesis, and the effect of RANKL and ZOL on osteoclastogenesis may be mediated by NF-kappaB p50 and c-Jun.

Morphology, composition, and bioactivity of strontium-doped brushite coatings deposited on titanium implants via electrochemical deposition.

Surface modification techniques have been applied to generate titanium implant surfaces that promote osseointegration for use in dental applications. In this study, strontium-doped brushite coatings were deposited on titanium by electrochemical deposition. The phase composition of the coating was investigated by energy dispersive X-ray spectroscopy and X-ray diffraction. The surface morphologies of the coatings were studied through scanning electron microscopy, and the cytocompatibility and bioactivity of the strontium-doped brushite coatings were evaluated using cultured osteoblasts. Osteoblast proliferation was enhanced by the addition of strontium, suggesting a possible mechanism by which strontium incorporation in brushite coatings increased bone formation surrounding the implants. Cell growth was also strongly influenced by the composition of the deposited coatings, with a 10% Sr-doped brushite coating inducing the greatest amount of bone formation among the tested materials.