Both silicalite-1/SiC foam and ZSM-5/SiC foam may serve as novel bone replacement materials.

BACKGROUND: This study aimed to analyze the bioactivity and biocompatibility of silicon carbide (SiC) foam coated with one of two kinds of zeolite. METHODS: The surface charges, protein adsorption ability and mineralization ability were compared between silicalite-1/SiC foam and ZSM-5/SiC foam. RESULTS: Proliferation and differentiation of primary osteoblasts seeded on two types of materials were significantly higher when compared with uncoated SiC foam after 7 d. There was no significant difference in the bioactivity between silicalite-1/SiC foam and ZSM-5/SiC foam. Silicalite-1/SiC foam and ZSM-5/SiC foam had no cytotoxic effect on primary osteoblasts. CONCLUSIONS: These results suggest both silicalite-1/SiC foam and ZSM-5/SiC foam have the potential for use as novel bone replacement materials.

Acceleration of Bone Defect Healing and Regeneration by Low-Intensity Ultrasound Radiation Force in a Rat Tibial Model.

The objective was to evaluate the effect of low-intensity pulsed ultrasound (LIPUS)-induced acoustic radiation force on trabecular bone defect repair and healing in a rat tibial model. A uniform surgical defect, 3.5 mm in diameter, was generated in the proximal bilateral tibial region of rats (N = 20). LIPUS was applied to the defects in the left tibia for 20 min every day for 2 wk. Contralateral defects in the right tibia served as a control without active LIPUS treatment. The micro-computed tomography data revealed that LIPUS-treated tibia exhibited higher bone volume/total volume, connectivity density, trabecular number, and bone mineral density and significantly lower trabecular separation. Histomorphometry analysis indicated a similar trend. Mechanical testing data revealed that LIPUS treatment significantly increased bone stiffness relative to that of the control group. Short-term (2-wk) LIPUS therapy initiated trabecular bone repair and regeneration in large trabecular bone defects, whereas cortical bone remained in the initial non-mineralization stage.

Assessment of calcium sulfate hemihydrate-Tricalcium silicate composite for bone healing in a rabbit femoral condyle model.

Calcium sulfate or plaster of Paris (POP) is considered as a bone cement with a fast degradation rate, which frequently makes it resorb before the bone defect area is completely filled by new bone. The incorporation of tricalcium silicate (C3S) into POP cement has been proven as a feasible approach to reduce the in vitro degradation rate and improve the in vitro bioactivity of the material. However, the in vivo performance of the POP/C3S composite cement is still unclear. Therefore, the aim of the present study is to assess the biodegradability and osteogenesis of POP/C3S composite cement in comparison with those of POP bone cement. To carry out the in vivo evaluation, POP and POP/C3S cements were implanted into a femoral condyle defect model in rabbits (5 mm diameter × 10 mm length) for 4, 8, and 12 weeks duration. The area of the remaining cement and new bone regeneration in bone defect were investigated and quantitatively measured using radiography, micro-computed tomography, and histological staining. For both cements, no sign of inflammation was observed. POP cement was completely degraded at the 8th week of post-implantation. By contrast, only approximately 50% by volume of POP/C3S composite cement degraded at the 12th week, which allowed a long-term framework for new bone formation. The osteogenic ability of POP/C3S composite cement was significantly superior to that of POP as indicated by the higher mineralization rate and maturity of the newly formed bone around the composite cement. In summary, our findings demonstrated that the in vivo degradation behaviors and osteogenic ability of POP cement could be improved by incorporating C3S in vivo, suggesting that POP/C3S composite cement has potential as a biodegradable cement for bone repair.

Expression of E-cadherin, vimentin and ß-catenin in ameloblastoma and association with clinicopathological characteristics of ameloblastoma.

OBJECTIVE: Ameloblastoma shows invasive growth and is susceptible to recurrence. This study aimed to detect the expression of E-Cadherin, Vimentin and ß-Catenin (proteins related to epithelial mesenchymal transformation (EMT) in the ameloblastoma and to explore association with clinicopathological characteristics of ameloblastoma. METHODS: Immunohistochemistry was employed to detect the protein expression of E-Cadherin, Vimentin and ß-Catenin in the ameloblastoma, and its association with clinicopathological characteristics of ameloblastoma was further evaluated. RESULTS: E-Cadherin expression was reduced or absent on the membrane of the peripheral columnar and cubic epithelial cells; Vimentin expression was high in the interstitium as well as epithelial cells in ameloblastoma; E-Cadherin expression was negatively related to Vimentin expression. ß-catenin expression on the membrane of ameloblastoma epithelial cells reduced, but its ectopic expression was observed in the cytoplasm and/or nucleus. CONCLUSION: EMT related proteins E-Cadherin, ß-catenin and Vimentin are involved in the occurrence and development of ameloblastoma and these proteins can be used as biomarkers of invasiveness of ameloblastoma.

Association between clincopathological characteristics and hTERT expression as well as telomere length in ameloblastoma.

OBJECTIVE: This study aimed to investigate the human telomerase reverse transcriptase (hTERT) expression and telomere length in ameloblastoma, and expolre the role of hTERT in the invasiveness and recurrence of ameloblastoma. METHODS: hTERT expression was detected by immunohistochemistry and Western blotting and telomere length by fluorescence in situ hybridization (FISH) in human ameloblastoma, normal mucosa, and oral squamous cell carcinoma (OSCC). Association between clincopathological characteristics and hTERT expression as well as telomere length in ameloblastoma was analyzed. RESULTS: hTERT expression in ameloblastoma was higher than that in normal oral mucosa, and the highest in OSCC (P<0.05). The hTERT positive rate and expression increased with the recurrence and malignant transformation. hTERT expression was significantly different among different types of ameloblastoma. The telomere was the shortest in OSCC and the longest in normal oral mucosa. CONCLUSION: Ameloblastoma has shortened telomere, and is positive for hTERT expression which is related to the recurrence and malignancy of ameloblastoma. These findings indicate that telomerase is involved in the occurrence and development of ameloblastoma.

Expression of phosphorylated Akt/mTOR and clinical significance in human ameloblastoma.

This study aimed to evaluate the expression of AKT and phosphorylated AKT (p-Akt) in human ameloblastoma (AB). Immunohistochemistry showed human AB was positive for Akt and Akt expression was mainly found in the cytoplasm of epithelial cells. The Akt expression in AB was significantly higher than that in normal oral mucosa (NOM), but still lower than that in oral squamous cell carcinoma (OSCC). NOM was negative for p-Akt, but AB was positive for p-Akt. In some AB tissues, p-Akt expression was found in both cytoplasm and nucleus. Akt expression in AB was significantly different from that in NOM and OSCC. The p-Akt in AB was markedly higher than that in NOM, but lower than that in OSCC. mTOR expressed in cytoplasm in AB, but not in NOM. P-mTOR expressed on cell membrane in NOM, while in cytoplasm and nucleus in Ab. Results of western blot assay showed that Akt expression was found in all the AB tissues, and increased in tissues with malignant transformation. In addition, the p-Akt expression also markedly increased in AB, but was still lower than that in OSCC tissues. Compared to NOM, mTOR and p-mTOR expression significantly increased in AB. BandScan 5.0 software was used to detect the optical density of protein bands. Results showed p-Akt, mTOR and p-mTOR expression in AB was markedly different from that in control group.

[Raman spectroscopic analysis of post-cement-root canal dentin interface].

OBJECTIVE: To examine the compositions of those adhesion modes between luting cements and canal dentin, and to evaluate the dentin-cement-post interface by Laser-Ranian spectroscopy. METHODS: Three representative luting cements (zinc phosphate, glass ionomer and resin cements), two kinds of prefabricated posts (titanium and fiber-glass), six extracted intact human maxillary anterior teeth were used canal dentin after endodontic treatment. Laser-Raman spectroscopy measure of cement, post and canal dentin before and after luting together. RESULTS: There are no evident Raman spectra change cross the ZPC/dentin interface and glass ionomer/dentin interface, while cross the resin/dentin interface and resin/glass fiber post interface can be seen special Raman spectra. CONCLUSION: Laser-Raman microspectroscopy is a useful analytical technique for evaluation interface between dentin and luting cements. Resin cement may interact with dentin and glass fiber post.

[Effects of investment materials on cast shrinkage of base metal alloys].

OBJECTIVE: To compare the influence of different investment materials, methods and crown height on the cast shrinkage of full crowns made of dental base metal alloy. METHODS: All of the 288 wax patterns were made and divided into three groups according to their crown height. In every group, wax patterns were invested in metal rings and paper rings with three types investment material and cast with base metal alloys. Then the inside diameters of castings were measured and analyzed by statistical package SPSS. RESULTS: Differences between groups invested with the three types of material were significant(P < 0.01). There were significant difference between the groups investing with metal rings and paper rings(P < 0.01). CONCLUSION: The component of investment material and invested ring can affect the cast shrinkage of dental base metal alloy apparently.

[The study of compressive strength of phosphate-bonded investment materials].

OBJECTIVE: The purpose of this study was to compare the compressive strength of phosphate-bonded investments. METHODS: The three sorts of investments were mixed according to manufacturer's recommendation before poured in the molds. After heated up to 900 degrees C, every sample was mounted on a universal experimental machine to test its compressive strength in ambient. RESULTS: Significant differences were found between the four groups(P < 0.01). CONCLUSION: From the data above it is concluded that the compressive strength of X-20 Chrome Investment mixed with the special liquid was the highest.