Mechanical properties, hemocompatibility, cytotoxicity and systemic toxicity of carbon fibers/poly(ether-ether-ketone) composites with different fiber lengths as orthopedic implants.

Poly(ether-ether-ketone) (PEEK) has attracted more and more attention due to its chemical resistance, biocompatibility and other properties. Furthermore, carbon fibers-PEEK composite (CF-PEEK) has been considered as a novel implant because of its high mechanical strength and elastic modulus that matching with human bones. However, the length of CF has a great influence on mechanical strength and elastic modulus of the randomly distributed chopped CF-PEEK composites. In this work, CF-PEEK composites with more than 10 times length difference of fibers (length of short CF: 150-200 µm and length of long CF: 2-3 mm) were studied. As the results shown, the mechanical strength (including tensile strength, bending strength and compressive strength) of long CF-PEEK composites were more than two times of that of short CF-PEEK composites. Meanwhile, tensile modulus and bending modulus of the two kinds of composites matched well with the modulus of human cortical bone. In addition, according to the results of cytotoxicity test and hemocompatibility assessment, it indicated that the two kinds of CF-PEEK composites showed mild toxicity and no hemolytic reaction. And the histopathological section of systemic toxicity test showed that the CF-PEEK composites had no obvious acute toxicity to organisms.

Clinical application of the pedicle in vitro restorer in percutaneous kyphoplasty.

BACKGROUND: Percutaneous kyphoplasty (PKP) is widely applied for the treatment of osteoporotic vertebral compression fractures (OVCFs) and has achieved satisfactory clinical results. With the accumulation of clinical cases and prolonged follow-up times, the inability to reconstruct vertebral height defects has attracted more and more attention. A comparison of clinical effects was retrospectively reviewed in 72 patients who underwent simple PKP or pedicle in vitro restorer (PIVR) combined with PKP to discuss the clinical application of self-developed PIVR used in PKP. METHODS: From August 2013 to August 2016, 72 patients with OVCFs were treated surgically, with 30 patients undergoing PKP (group A) and 42 undergoing PIVR combined with PKP (group B). Operation-related situations, radiological data, and related scores were compared between the two groups by corresponding statistical methods. RESULTS: Bone cement was successfully injected into 72 vertebral bodies. Sixty-three cases were followed up for an average of 14 months. There were significant differences between the two groups in the improvement of the height of the vertebral body, sagittal Cobb angle, and visual analogue scale (VAS) 1 week after the operation (P < 0.05), and the improvements of group B were better than those in group A. The cement leakage ratio was significantly different between the two groups (P < 0.05). The Oswestry Disability Index (ODI) at last follow-up was significantly different between the two groups (P < 0.05). There was no significant difference in the incidence of recurrent vertebral fractures between the two groups at the last follow-up (P > 0.05). CONCLUSION: PIVR combined with PKP can overcome the limitations of PKP alone, that is, hardly restoring vertebral height and height being easily lost again with balloon removal. The combined method can also restore the vertebral fractures to a satisfactory height and effectively maintain the stability of the spine, which improves the long-term quality of life of patients. Thus, PIVR combined with PKP is a better choice for patients with OVCFs.

The Role of Minimally Invasive Vertebral Body Stent on Reduction of the Deflation Effect After Kyphoplasty: A Biomechanical Study.

STUDY DESIGN: Biomechanical investigation using cadaver spines. OBJECTIVE: The aim of the present study was to assess the magnitude of the deflation effect after balloon kyphoplasty (BKP) or use of minimally invasive vertebral body stent (MIVBS) in in vitro biomechanical condition. SUMMARY OF BACKGROUND DATA: BKP is a well-established minimally invasive treatment option for osteoporotic vertebral compression fractures. However, this technique can lead to a secondary height loss-known as the "deflation effect"-causing intrasegmental kyphosis and an overall alignment failure. METHODS: The study was conducted on 24 human cadaveric vertebral bodies (T12-L5). After creating a compression fracture model, the fractured vertebral bodies were reduced by BKP (n = 12) or by MIVBS (n = 12) and then augmented with polymethyl methacrylate bone cement. Each step of the procedure was performed under fluoroscopic guidance and the results were analyzed quantitatively. Finally, the strength and stiffness of augmented vertebral bodies were measured by biomechanical tests. RESULTS: Complete initial reduction of the fractured vertebral body height was achieved by both systems. Secondary loss of reduction after balloon deflation was significantly greater in the BKP group (2.36 ±â€Š0.63 mm vs. 0.34 ±â€Š0.43 mm in the MIVBS group; P < 0.05). Height gain was significantly higher in the MIVBS group (77.68% ±â€Š11.46% vs. 34.87% ±â€Š13.16% in the BKP group; P < 0.05). Increase in the kyphotic angle gain (relative to the preoperative kyphotic angle) was significantly more in the MIVBS group (95.60% ±â€Š6.12% vs. 77.0% ±â€Š4.94% in the BKP group; P < 0.05). Failure load was significantly higher in the MIVBS group (189% ±â€Š16% vs. 146% ±â€Š14%; P < 0.05). However, stiffness was not significantly different between the two groups. CONCLUSION: The deflation effect after BKP can be significantly decreased with the use of the MIVBS technique. LEVEL OF EVIDENCE: N/A.

Calcitonin induces collagen synthesis and osteoblastic differentiation in human periodontal ligament fibroblasts.

BACKGROUND: Extracellular matrix (ECM) secretion and osteogenic differentiation in periodontal ligament fibroblasts (PDLF) facilitate the neogenesis of alveolar bone, which is the cellular basis for alveolar bone repair. Calcitonin (CT) has been reported to play an important role in promoting ECM expression and inducing osteogenic differentiation in osteoblast, but its effects on PDLFs remain obscure. METHODS: The expression of CT, transforming growth factor-beta 1(TGF-ß1) and bone morphogenetic protein (BMP) in gingival crevicular fluid (GCF) was measured by ELISA. The effects of CT on collagen synthesis and osteogenic differentiation in hPDLFs were investigated by using the primarily cultured hPDLFs infected with adenovirus carrying the CT gene. Gene expression was measured by quantitative PCR and western blot. RESULTS: The expression of CT in gingival crevicular fluid (GCF) of patients with periodontitis was significantly higher than that of healthy subjects. In addition, CT expression correlated with the clinical indexes including probing pocket depth (PPD), clinical attachment level (CAL), and gingival index (GI). The in vitro study demonstrated that overexpression of CT by adenovirus infection increased the expression of TGF-ß1, collagen type I and III, and osteoblastic markers including BMP-2/-4, alkaline phosphatase and osteocalcin in human PDLFs. Moreover, CT-enhanced collagen synthesis was abrogated in hPDLFs transfected with TGF-ß1 siRNA, and CT-induced osteoblastic differentiation was blocked in hPDLFs by BMPs inhibitor noggin. CONCLUSIONS: These results suggest that CT promotes collagen synthesis and osteogenic differentiation in hPDLFs via the TGF-ß1 and BMPs signaling pathways, respectively.

Functional hydroxyapatite bioceramics with excellent osteoconductivity and stern-interface induced antibacterial ability.

The biocompatibility and antibacterial properties of hydroxyapatite (HAp) bioceramics are crucial in medical applications. However, it is still a challenge to control HAp with antibacterial ability while maintaining other biological properties in the development of bioactive bone implants. Herein, we report functional silver ion substituted HAp bioceramics with excellent osteoconductivity and efficient antibacterial activity and propose a stern-interface induced antibacterial mechanism of such bioactive ceramics. In this antibacterial process, the concentration of Ag(+) at the stern-interface of Ag/HAp bioceramics is nearly 5 times higher than that in the bulk solution due to the trace dopant Ag(+) enrichment in the stern layer of the electric double layer at the negatively charged surface of Ag/HAp bioceramics. Trace Ag-doping in HAp induces a positive shift of zeta potential and increase of hydrophilicity, which may help inhibit bacterial proliferation. The positive osteoblast adhesion, proliferation and differentiation of ultra-trace doped Ag/HAp are also demonstrated through actin cytoskeleton staining, MTT and alkaline phosphatase (ALP) activity assays. This work may enlighten us on the artificial design of novel smart anti-infective bone grafts using ultra-trace functional elements and also suggest its potential applications in orthopedic surgery and bone osseointegration.

Does matching relation exist between the length and the tilting angle of terminal implants in the all-on-four protocol? stress distributions by 3D finite element analysis.

PURPOSE: To explore whether there is matching relation between the length and the tilting angle of terminal implants in the All-on-Four protocol by studying the effects of different implant configurations on stress distributions of implant, bone, and framework. MATERIALS AND METHODS: Four implants were employed to support a full-arch fixed prosthesis and five three-dimensional finite element models were established with CT images, based on the length (S and L) and distal tilt angle (0°, 30° and 45°) of terminal implants for an edentulous mandible, which named: Tilt0-S, Tilt30-S, Tilt30-L, Tilt45-S and Tilt45-L. An oblique 240 N was loaded at second molar. The von Mises Stresses were analyzed. The implants were consecutively named #1 to #4 from the loading point. RESULTS: 1) Tilt0-S had the greatest stress on the implants, with the other groups exhibiting variable reductions; the four implants of Tilt45-L demonstrated the greatest reduction in stress. 2) Tilt0-S had the greatest stress at bone around #1 implant neck, and Tilt45-L exhibited the least stress, which was a 36.3% reduction compared to Tilt0-S. 3) The greatest stress in the framework was found on the cantilevers distal to #1 implant. Tilt45-S exhibited the least stress. CONCLUSION: Matching different length and tilting angle of the terminal implants led to variable stress reductions on implants, bone and the superstructure. By optimizing implant configuration, the reduction of stress on implants and surrounding bone could be maximized. Under the present condition, Tilt45-L was the preferred configuration. Further clinical testings are required.

Ultra-trace silver-doped hydroxyapatite with non-cytotoxicity and effective antibacterial activity.

Hydroxyapatite (HAp) nanocrystals as the main inorganic component in hard tissue have been extensively studied for bone regeneration and dental implant treatment. However, failure of surgical reconstruction often occurs owing to the lack of effective antibacterial ability of HAp. It is still a challenge to develop artificial HAp with both efficient antibacterial ability and proper biological properties. Herein, a series of ultra-trace Ag-doped HAp nanocrystals have been elaborately prepared with the optimal doping concentration from 0.27 ppm to 2.2 ppm, which present non-cytotoxicity while possess effective bacteria reduction ability. Ultra-trace Ag-doped HAp nanocrystals possess higher protein adsorption than pure HAp nanocrystals due to the trace doping-induced less negative surface potential. The ultra-trace Ag-doped HAp nanocrystals showed effectively antibacterial ability, non-cytotoxicity and enhanced adsorbability that made them ideal materials for various biocompatible and antibacterial applications.

The effect of periodontal treatment on hemoglobin a1c levels of diabetic patients: a systematic review and meta-analysis.

BACKGROUND: There is growing evidence that periodontal treatment may affect glycemic control in diabetic patients. And several systematic reviews have been conducted to assess the effect of periodontal treatment on diabetes outcomes. Researches of this aspect are widely concerned, and several new controlled trials have been published. The aim of this study was to update the account for recent findings. METHODS: A literature search (until the end of January 2014) was carried out using various databases with language restriction to English. A randomized controlled trial (RCT) was selected if it investigated periodontal therapy for diabetic subjects compared with a control group received no periodontal treatment for at least 3 months of the follow-up period. The primary outcome was hemoglobin A1c (HbA1c), and secondary outcomes were periodontal parameters included probing pocket depth (PPD) and clinical attachment level (CAL). RESULTS: Ten trials of 1135 patients were included in the analysis. After the follow-up of 3 months, treatment substantially lowered HbA1c compared with no treatment after periodontal therapy (-0.36%, 95%CI, -0.52% to -0.19%, P<0.0001). Clinically substantial and statistically significant reduction of PPD and CAL were found between subjects with and without treatment after periodontal therapy (PPD -0.42 mm, 95%CI: -0.60 to -0.23, P<0.00001; CAL -0.34 mm, 95%CI: -0.52 to -0.16, P=0.0002). And there is no significant change of the level of HbA1c at the 6-month comparing with no treatment (-0.30%, 95%CI, -0.69% to 0.09%, P=0.13). CONCLUSIONS: Periodontal treatment leads to the modest reduction in HbA1c along with the improvement of periodontal status in diabetic patients for 3 months, and this result is consistent with previous systematic reviews. And the effect of periodontal treatment on HbA1c cannot be observed at 6-month after treatment.

[Effect of the number and inclination of implant on stress distribution for mandibular full-arch fixed prosthesis].

OBJECTIVE: To study the effect of implant number and inclination on stress distribution in implant and its surrounding bone with three-dimensional finite element analysis. METHODS: A special denture was made for an edentulous mandible cast to collect three-dimensional finite element data. Three three-dimensional finite element models were established as follows. Model 1: 6 paralleled implants; model 2: 4 paralleled implants; model 3: 4 implants, the two anterior implants were parallel, the two distal implants were tilted 30° distally. RESULTS: Among the three models, the maximum stress values found in anterior implants, posterior implants, and peri-implant bone were modle 3

[Influence of TiN, TiCN coating on corrosion resistance of dental pure titanium].

PURPOSE: To investigate the effects of TiN and TiCN coating on corrosion resistance of pure titanium in the simulated oral environment. METHODS: The dental pure titanium commonly used in making removable denture was casted with 15 specimens, 10mm × l0mm × 1mm in size. The specimens were randomly divided into group A, group B and group C. In the group B and group C, the specimens were coated with a thickness of 2.5µm TiN and TiCN coating on surface by multi-arc physical vapor deposition, respectively. After microscopic energy spectrum analysis, microstructure and phase diffraction were examined by FESEM. Hardness and Young modulus of the various coating were determined by nanoindentation. The polarization curves of all specimens in artificial saliva were measured by PARSTAT' 2273 electrochemical station. The data were analyzed with SPSS 17.0 software package for t test, one-way ANOVA and nonparametric test. RESULTS: Both the microhardness and elastic modulus in the group B and group C were significantly superior to those in the group A (P<0.001). Meanwhile, both the microhardness and elastic modulus in the group C were significantly higher than those in the group B (P<0.01). Corrosion potential (Ecorr) was group A > group B > group C (P<0.05). However, corrosion current density (Icorr) was significantly lower in the group A than in the group B, and in the group A than in the group C (P<0.01), while not significantly different between the B and group C (P>0.05).Breakdown potential (Ebreak) was group A