Enhanced osteogenesis of quasi-three-dimensional hierarchical topography.

Natural extracellular matrices (ECMs) are three-dimensional (3D) and multi-scale hierarchical structure. However, coatings used as ECM-mimicking structures for osteogenesis are typically two-dimensional or single-scaled. Here, we design a distinct quasi-three-dimensional hierarchical topography integrated of density-controlled titania nanodots and nanorods. We find cellular pseudopods preferred to anchor deeply across the distinct 3D topography, dependently of the relative density of nanorods, which promote the osteogenic differentiation of osteoblast but not the viability of fibroblast. The in vivo experimental results further indicate that the new bone formation, the relative bone-implant contact as well as the push-put strength, are significantly enhanced on the 3D hierarchical topography. We also show that the exposures of HFN7.1 and mAb1937 critical functional motifs of fibronectin for cellular anchorage are up-regulated on the 3D hierarchical topography, which might synergistically promote the osteogenesis. Our findings suggest the multi-dimensions and multi-scales as vital characteristic of cell-ECM interactions and as an important design parameter for bone implant coatings.

In vivo comparison of bone formation on titanium implant surfaces coated with biomimetically deposited calcium phosphate or electrochemically deposited hydroxyapatite.

PURPOSE: The purpose of this study was to investigate and compare bone formation on titanium implant surfaces coated with biomimetically deposited calcium phosphate (BDCaP) or electrochemically deposited hydroxyapatite (EDHA). MATERIALS AND METHODS: The implants were separated into three groups: a control group, a BDCaP group, and an EDHA group. Surface analysis was performed by field-emission scanning electron microscopy, x-ray diffractometry, and Fourier transform infrared spectroscopy. Implants were inserted in a randomized arrangement into rabbit tibiae. After 2, 4, and 8 weeks, the tibiae were retrieved and prepared for histomorphometric evaluation. RESULTS: Field-emission scanning electron microscopy showed that the BDCaP crystals were flakelike and the EDHA crystals were rodlike with a hexagonal cross section. X-ray diffractometric patterns and Fourier transform infrared spectroscopy spectra showed that the BDCaP coating consisted of HA and octacalcium phosphate, whereas the EDHA coating consisted of HA. Histologic observation showed that new bone on the EDHA-coated implant became mature after 4 weeks, while new bone on the control and BDCaP-coated implants was mature after 8 weeks. The EDHA implant showed significantly greater BIC and bone area compared to the control and BDCaP implants during 4 to 8 weeks. The BDCaP coating failed to show increased bone formation during the test period. CONCLUSION: The present EDHA coating has good bone formation properties, while the BDCaP coating has weaker bone formation properties.

Biomechanical comparison of biomimetically and electrochemically deposited hydroxyapatite-coated porous titanium implants.

PURPOSE: The purpose of this study was to investigate the effects of biomimetically and electrochemically deposited hydroxyapatite on the fixation of an implant with bone tissue. MATERIALS AND METHODS: Implants were separated into 3 groups: roughened group, biomimetically deposited calcium-phosphorus (BDCaP) group, and electrochemically deposited hydroxyapatite (EDHA) group. We randomly inserted 90 implants into the femurs of 45 rabbits. After 2, 4, and 8 weeks, the femurs were retrieved and prepared for removal torque tests (RTQs) and field-emission scanning electron microscopy observation. RESULTS: During the test period, the EDHA group showed significantly greater RTQ values than did the roughened group and BDCaP group. The BDCaP group failed to increase the RTQ values compared with the roughened group. Field-emission scanning electron microscopy observation showed that the amount of attached bone tissue on the EDHA-coated implant surface was more than that on the roughened and BDCaP-coated implant surfaces during the test period. CONCLUSION: The electrochemical hydroxyapatite coating contributes to the fixation between bone and implant compared with the roughened surface, whereas the biomimetic calcium-phosphorus coating has little effect on the fixation.

An animal model for inducing anterior disc displacement of the temporomandibular joint.

AIMS: To develop an animal model of anterior disc displacement (ADD) without the need for opening the temporomandibular joint (TMI) capsule. METHODS: Thirty-two healthy adult Japanese white rabbits were used in this study. Four rabbits were dissected to familiarize the investigators with the anatomy of the TMJ. Sixteen animals were subjected to surgical ADD in the right TMJ, 8 animals had a sham operation, and 4 animals were not operated (normal controls). Four rabbits from the experimental ADD group and 2 from the sham group were sacrificed 1, 2, 4, and 8 weeks, respectively. The rabbits in normal control group were sacrificed at the beginning of the experiment. Animal behaviors as well as macro- and microchanges in the TMJs were investigated. RESULTS: Fifteen right TMJ discs in the 16 experimental rabbits were successfully displaced anteriorly, and the degree of ADD in the experimental group was similar. The mandible of each ADD rabbit deviated to the left side with inclined attrition of the incisors. Some histologic changes appeared in the experimental TMJs. CONCLUSION: This ADD technique without the need for opening the TMJ capsule is effective, and the model is suitable for studying ADD of the TMJ.

Effect of Capsaicin Cream on the Secretion of the Submandibular and Parotid Gland in the General Population with Different Chilli-eating Habits.

OBJECTIVE: To investigate the effect of capsaicin cream on the secretion of the submandibular gland (SMG) and the parotid gland (PG) in the general population, with different chilli-eating habits. METHODS: In two groups with different chilli-eating habits, the salivary flow rate of the SMG and the PG was detected at statics and different times, after application of capsaicin cream. RESULTS: In both groups, the topical application of capsaicin cream could significantly increase the salivary secretion of SMG (P < 0.05), but the increase in the salivary flow rate of the SMG between the two groups had no significant difference (P > 0.05). On the other hand, although the salivary flow rate of PG also increased after stimulation, the increase had no statistical difference (P > 0.05). CONCLUSION: The application of capsaicin cream can effectively promote the secretion of the SMG and the PG, and its effect is independent of chilli-eating habits, which indicates that topical application of capsaicin cream can be considered as a potential treatment for the hypofunction of the salivary gland.

Gene expression of fibrinolytic factors urokinase plasminogen activator and plasminogen activator inhibitor-1 in rabbit temporo-mandibular joint cartilage with disc displacement.

BACKGROUND: The urokinase plasminogen activator system is believed to play an important role in degradation of the extracellular matrix associated with cartilage and bone destruction; however its precise roles in temporomandibular disorders have not yet been clarified. The aims of this study were to investigate the gene expression of fibrinolytic factors urokinase plasminogen activator (uPA) and plasminogen activator inhibitor-1 (PAI-1) in the articular cartilage of rabbit temporomandibular joint (TMJ) with disc displacement (DD) and to probe the relationship between fibrinolytic activity and cartilage remodeling. METHODS: Disc displacement of right joints was performed in 36 of 78 rabbits under investigation. The animals were sacrificed at 4 days and 1, 2, 4, 8 and 12 weeks after surgery, respectively. The right joints of these animals were harvested and processed for the examination of mRNA expression of uPA and PAI-1 in articular cartilage using in situ hybridization techniques. RESULTS: The expression of uPA and PAI-1 was co-expressed weakly in the chondrocytes from transitive zone to hypertrophic zone and mineralized zone, while no hybridizing signals were shown in proliferative zone and superficial zone in control rabbits. The most striking was the up-regulation of uPA and PAI-1 mRNA in 4-day rabbits postoperatively at the onset of cartilage degeneration. The strongest hybridizing signals for uPA and PAI-1 were seen in 2-week rabbits postoperatively. After 2 weeks, the expression of uPA and PAI-1 began to decrease and reached nearly normal level at 12 weeks. CONCLUSIONS: The expression of the uPA/PAI-1 system coincides with the pathological changes in condylar cartilage after DD. The uPA/PAI-1 system may be one of the essential mediators in articular cartilage remodeling.

Clinical application and histological observation of pedicled buccal fat pad grafting.

OBJECTIVE: To introduce the applied anatomy of pedicled buccal fat pad (BFP) graft and a series of histological changes in the healing process of BFP as an uncovered pedicled graft. METHODS: The healing processes of BFP are demonstrated via uncovered pedicled grafts on rabbits in histological examination. Uncovered buccal fat pads were used to repair soft tissue defects in rabbit oral cavities. RESULTS: The uncovered buccal fat pads showed complete epithelialization of their oral surfaces at 6 to 8 weeks after surgery and were slowly replaced by fibrous tissue. CONCLUSIONS: Advantages of the pedicled buccal fat pad graft include an anatomic region that is consistent and easy to excise. The operation can be performed in one incision, affecting neither appearance nor function of the area. Use of the buccal fat pad provides a good reconstruction of soft tissue defects in the mouth.

[Histological observation of the interface of oral epithelium and titanium implant with titanium dioxide on the surface]

OBJECTIVE: To investigate the healing process at the interface between oral epithelium and a titanium implant with titanium dioxide on the surface and whether a good epithelial barrier could be formed. METHODS: Titanium implants with titanium dioxide on the surface were placed in the mandibular alveolar area of Beagle dogs after their premolars had been removed three months previous. On the 15th day, second month and loading second month after implantation specimens were taken and examined after HE staining as well as by transmission electron microscopy. RESULTS: Fifteen days after implantation the epithelial collar was formed, junctional epithelium actively regenerated and attachment to the matrix on the surface of the implant occurred by hemidesmosomes. Two months after implantation junctional epithelium was increasing, showing three to four layers consistent with each other. Junctional epithelium appeared to be generated when stimulated by inflammation and shaped into epithelium rete pegs after loading for two months. CONCLUSION: Oral junctional epithelium can attach very well to titanium implants with titanium dioxide on the surface which also provides a biological barrier.

[Experimental study on allogeneic mandible transplantation combined with basic fibroblast growth factor]

OBJECTIVE: To study the effect of basic fibroblast growth factor(b-FGF) on revascularization and bone remodeling of allogeneic mandible transplantation in repair of mandible defects in rabbits. METHODS: The mandible defects of 20 adult rabbits were created in both sides. The defects on the left side were implanted with allogeneic bone and local administration of b-FGF; the defects on the right side were only repaired with allogeneic bone as control group. At 1, 3 months after operation, the revascularization and bone remodeling were observed by ink-gelation vascular perfusion-transparency and histological examination. RESULTS: The allogeneic bone and b-FGF group had more marked vascularization and more quick and complete bone formation than control group. CONCLUSION: b-FGF can improve revascularization and bone formation after allogeneic mandible transplantation; allogeneic bone combined with b-FGF is a promising bone substitute in clinical uses.

Effects of biomimetically and electrochemically deposited nano-hydroxyapatite coatings on osseointegration of porous titanium implants.

OBJECTIVE: The objective of this study was to evaluate and compare the effects of biomimetically and electrochemically deposited nano-hydroxyapatite (HA) coatings on the osseointegration of porous titanium implants after 6 and 12 weeks of insertion in a rabbit bone model. STUDY DESIGN: Forty-two roughened implants were separated into 3 groups: roughened group, biomimetically deposited CaP (BDCaP) group, and electrochemically deposited HA (EDHA) group. Implant surface morphology of 3 groups (n = 6) was performed by field-emission scanning electron microscope (FSEM). Thirty-six implants were randomly inserted into tibias of 18 rabbits. After 6 and 12 weeks, tibias were retrieved and prepared for histomorphometric evaluation. RESULTS: FSEM showed the BDCaP crystals were flakelike, whereas the EDHA crystals were rodlike with a hexagonal cross section. Histological observation showed bone growth along the surfaces after 6 weeks. New bones were also seen on the BDCaP and EDHA implant surfaces in the marrow space. New bone on the roughened and EDHA implants became mature after 12 weeks. The EDHA implant showed significantly greater BIC and bone area compared with the roughened and BDCaP implants during 6 to 12 weeks (P < .05). The BDCaP implants did not evidently increase BIC and bone area compared to the roughened implants during the test period (P > .05). CONCLUSION: These results suggest that the EDHA coating has a better bone integration potential than does the BDCaP coating.

Intraoral granulocytic sarcoma presenting as multiple maxillary and mandibular masses: a case report and literature review.

Granulocytic sarcoma (GS) is an unusual localized tumor composed of immature granulocytic precursor cells that occurs in extramedullary sites. However, GS involving the oral cavity is rare. We report a case of intraoral GS with an unusual clinical presentation, including a history of chronic myelogenous leukemia in remission, multiple maxillary and mandibular gingival masses mimicking acute inflammation that developed over a short period, complete remission after 1 week of treatment with imatinib mesylate (Gleevec), and no bone marrow or peripheral blood involvement over a 6-month follow-up period. To our knowledge, this is the first report of treatment of intraoral GS with Gleevec resulting in a complete remission.

[Oral lymphoepithelial cyst: report of 3 cases].

Three cases with oral lymphoepithelial cyst were reported in this paper. The most frequent site of the cyst was mouth floor, and the cyst was often misdiagnosed as mucous cyst and other diseases of cyst. Histopathologically, the central cystic lesion was lined with stratified squamous epithelium. Simultaneously, there were lymphoid cells located at the surrounding of the cystic fibrous connective tissue. Oral lymphoepithelial cyst was regarded to originate from secretory duct of the sublingual gland and the small salivary gland epithelium. With chronic stimuli, the epithelium of secretory duct was squamous metaplasia. The deciduous cells in the inner side of the duct induced the infiltration of the surrounding lymphocytes. The relevant literatures were reviewed regarding to the histological origin and the pathogenesis of the disease to provide some references for diagnosis and treatment of this disease.

[Effects of surface potentials of tooth hard tissue on bone remodeling in rabbit tibiae].

OBJECTIVE: To investigate the influence of surface potentials of tooth hard tissue on bone remodeling. METHODS: After insured the surface potentials of human extracted teeth with electrochemical methods, teeth sections and artificial hydroxyapatite were implanted into 25 rabbits' tibiae. The rabbits were sacrificed at 1, 2, 4, 6 and 8 weeks after implantation, respectively. The bone regeneration was compared between opposite two sides (cathode side and anode side) of tooth sections using hematoxylin-eosin (HE) staining, tartrate-resistant acid phosphatase (TRAP) activity detecting and tetracycline tracing method. RESULTS: Resorption lacunae was seen in the tibiae facing to the enamel anode and new bone density in the implant bed near the cathode of tooth samples was much higher than that near the anode, while the number of TRAP positive cells near the cathode was smaller than that near the anode (P < 0.01). The fluorescent area of tetracycline tracing near the cathode was larger than that near the anode (P < 0.05). CONCLUSIONS: The cathode of tooth hard tissue (cementum) could improve or trigger new bone formation, while the other side, anode (enamel), could improve the bone resorption. This study suggests that tooth hard tissue's electrochemical characteristic might affect the remodeling of alveolar bone, and tooth supraeruption and the alveolar bone loss after tooth extraction might result from the redundant or lack of root electrochemical stimulation to bone.

[The morphology of the cells in the cartilage of rabbit mandibular condyle].

PURPOSE: To study the tissue layers and their function of the cartilage in mandibular condyle in rabbits. METHODS: Six adult Japanese white rabbits were subjected. Their temporomandibular joints were studied by immunohistochemistry for FGFR3 and PCNA, and in situ hybridization for aggrecan and collagen II mRNA expression, as well as ultrastructure. RESULTS: The upper proliferative cells did not express FGFR3, but the lower proliferative cells expressed FGFR3. Only few cells in the upper proliferative layer were PCNA positive, but all cells in the lower proliferative layer were positive for PCNA. No collagen II mRNA expression was found in the upper proliferative cell, but aggrecan and collagen II mRNA coexpressed in the lower proliferative layer. The cells in both layers were different in ultrastructure. CONCLUSION: The cartilage in mandibular condyle should have the 5 following tissue layer: fibrous layer, proliferative layer, transitional layer, cartilaginous layer and calcified cartilaginous layer. The cells in the proliferative layer are undifferentiated and the cells in the differentiated layer are prechondrocytes.

[The expression of MMP-9, MMP-2 in the remodeling bone tissue around implant during unloaded period].

OBJECTIVE: To discuss the function of MMP-9, MMP-2 in the remodeling bone tissue around implant during unloaded period. METHODS: At the anterior of the maxilla and mandibular of the Beagle dog, implants were placed at different periods, so the implant specimens of different periods were obtained after dogs were killed. The implant specimens were removed, fixed in 4% paraformaldehyde for 24 hours at 4 degrees C, decalcified with 10% EDTA at pH 7.2, embedded in paraffin wax and sectioned. The observation of the expression changes of the MMP-2, MMP-9 in the milien bone tissue of the implant at different periods were taken by immunohistochemical staining. RESULTS: Matrix metalloprotainase (MMP-9) was mostly expressed at the peripheral cytoplasmic of osteoclast, macrophage, lining cell and fibroblast. MMP-2 was mostly expressed at the peripheral cytoplasmic of osteoblast, fibroblast, some osteoclast also expressed this enzyme. CONCLUSION: MMP-2 and MMP -9 have an important function at the injured bone absorption, healing and bone remodeling after dental implant placement.