Effects of Atmospheric Pressure Plasma in the Treatment of Experimental Periodontitis in Beagle Dogs.

OBJECTIVE: The specific objective of this study was to evaluate the effects of atmospheric pressure plasma (APP) in the treatment of experimental periodontitis in Beagle dogs. METHODS: The APP jet was diagnosed using optical emission spectroscopy and laser-induced fluorescence spectroscopy. Six Beagles received stainless steel ligatures to establish experimental periodontitis model. The teeth in the control group were subjected to conventional root surface debridement (RSD) and chlorhexidine irrigation. The APP group also started with RSD and was then subjected to plasma irradiation. Clinical analyses including plaque index, modified sulcus bleeding index, pocket depth and attachment loss (AL), as well as cone-beam computed tomography (CBCT) analysis, were performed at baseline, 4th week, 8th week and 12th week after treatment. RESULTS: The results showed that typical reactive oxygen and nitrogen species were found in the full spectrum and the gas temperature of APP was close to room temperature. The highest concentrations of hydroxide and oxygen were obtained at 5 mm away from the nozzle. In both groups, all values in clinical examinations were significantly lower (P<0.05) at 12th week after treatment than those at baseline. At the 12th week, the AL in clinical examinations and the bone loss in CBCT images in the APP group were significantly lower than those in the control group (P<0.05). The hematoxylin-eosin staining showed more renascent alveolar bone in the APP group than in the control group. CONCLUSION: These findings suggested that APP has profound potential for use as an adjunct approach for periodontitis treatment.

Biomechanical Evaluation of Nano-Zirconia Coatings on Ti-6Al-7Nb Implant Screws in Rabbit Tibias.

The clinical success of dental implants can be improved by achieving optimum implant properties, such as their biomechanical and surface characteristics. Nano-structured coatings can play an important role in improving the implant surface. The purpose of the present study was to determine the most appropriate conditions for electrophoretic deposition (EPD) of nano-zirconia coatings on Ti-6Al-7Nb substrates and to evaluate the structural and biomechanical characteristics of these deposited coatings on the dental implants. EPD was used with different applied voltages and time periods to obtain a uniform layer of nano-zirconia on Ti-6Al-7Nb samples. The coated samples were weighed and the thickness of the product layer was measured. Surface analysis was performed by using optical microscopical examination, scanning electron microscope and X-ray diffraction phase analysis. For in vivo examination, 48 screw-designed implants (24 uncoated and 24 nano-zirconia coated) were implanted in both tibiae of 12 white New Zealand rabbits and evaluated biomechanically after 4- and 12-week healing intervals. Results revealed that the use of different conditions for EPD affected the final coating film properties. Increasing the applied voltage and coating time period increased the deposited nano-zirconia film thickness and weight. By selecting the appropriate coating conditions, and analyzing scanning electron microscopical examination and XRD patterns, this technique could produce a thin and continuous nano-zirconia layer with a uniform thickness of the Ti-6Al-7Nb samples. Mechanically, the nano-zirconia-coated implants showed a highly statistically significant difference in removal torque values, while histologically these coated implants enhanced and promoted osseointegration after 4 and 12 weeks of healing, compared with the uncoated ones. In conclusion, EPD is an effective technique for providing a high quality nano-zirconia coating film on dental implant surfaces. Moreover, the osseointegration of these coated dental implants is improved compared with that of uncoated ones.

New mini dental implant attachments versus O-ring attachment after cyclic aging: Analysis of retention strength and gap space.

Overdenture as a treatment modality for both partially and fully edentulous patients is costeffective and less expensive. The purpose of the present study was to examine the newly fabricated attachments by comparing them with conventional O-ring attachment in vitro in terms of retention force and cyclic aging resistance. A total of 150 samples were prepared and divided into five groups according to the materials used (O-ring attachment, Deflex M10 XR, Deflex Classic SR, Deflex Acrilato FD, and flexible acrylic resin). The retention force of different attachments was measured by a mini dental implant after three subsequent aging (0, 63, and 126) cycles in the circumstances similar to the oral environment. The gap space between the head of the implant and the inner surface of the attachments was detected. Two-way analysis of variance (ANOVA) analysis with multiple comparisons test was applied for statistical analysis. The results showed that Deflex M10 XR had the highest retention force and the lowest gap space after cyclic aging; in addition, by comparing the relative force reduction, the lowest values were obtained in the O-ring attachment and the highest values in the flexible acrylic resin attachment. The retention force measured after cyclic aging for the Deflex M10 XR attachment was greatly improved when compared with the O-ring attachment and other types of attachment materials; in addition, the Deflex M10 XR attachment exhibited the minimum gap space between the inner surface and the mini dental implant head. In conclusion, Deflex M10 XR has the ability to withstand weathering conditions and retains its durable and retentive properties after aging when compared with other attachments.

New Mini Dental Implant Attachments versus O-ring Attachment after Cyclic Aging: Analysis of Retention Strength and Gap Space / 华中科技大学学报（医学）（英德文版）

Overdenture as a treatment modality for both partially and fully edentulous patients is costeffective and less expensive.The purpose of the present study was to examine the newly fabricated attachments by comparing them with conventional O-ring attachment in vitro in terms of retention force and cyclic aging resistance.A total of 150 samples were prepared and divided into five groups according to the materials used (O-ring attachment,Deflex M10 XR,Deflex Classic SR,Deflex Acrilato FD,and flexible acrylic resin).The retention force of different attachments was measured by a mini dental implant after three subsequent aging (0,63,and 126) cycles in the circumstances similar to the oral environment.The gap space between the head of the implant and the inner surface of the attachments was detected.Two-way analysis of variance (ANOVA) analysis with multiple comparisons test was applied for statistical analysis.The results showed that Deflex M10 XR had the highest retention force and the lowest gap space after cyclic aging;in addition,by comparing the relative force reduction,the lowest values were obtained in the O-ring attachment and the highest values in the flexible acrylic resin attachment.The retention force measured after cyclic aging for the Deflex M10 XR attachment was greatly improved when compared with the O-ring attachment and other types of attachment materials;in addition,the Deflex M10 XR attachment exhibited the minimum gap space between the inner surface and the mini dental implant head.In conclusion,Deflex M10 XR has the ability to withstand weathering conditions and retains its durable and retentive properties after aging when compared with other attachments.

Bactericidal effect of plasma jet with helium flowing through 3% hydrogen peroxide against Enterococcus faecalis.

The aim of the present study was to assess the antimicrobial activity of plasma jet with helium (He) flowing through 3% hydrogen peroxide in root canals infected with Enterococcus faecalis. A total of 42 single-rooted anterior teeth were prepared, sterilized, inoculated with an E. faecalis suspension and incubated for 7 days. Next, the teeth were randomly divided into six experimental groups (including groups treated by plasma jet with or without He for different time durations) and one control group treated without plasma. The number of surviving bacteria in each canal was determined by counting the colony forming units (CFU)/ml on nutrient agar plates. The results indicated that statistically significant reduction in CFU/ml (P<0.005) existed for all treatment groups relative to the control group. The greatest reductions in CFU/ml were observed for Group 3 (7.027 log unit reduction) and Group 2 (6.237 log unit reduction), which were treated by plasma jet sterilization with He flowing through 3% hydrogen peroxide for 4 min or for 2 min, respectively. In addition, the reduction in Group 3 was significantly greater compared with that in Group 2 or in the groups treated by plasma jet sterilization without He flowing through 3% hydrogen peroxide for 1, 2 or 4 min. In conclusion, plasma jet with or without He flowing through 3% hydrogen peroxide can effectively sterilized root canals infected with E. faecalis and should be considered as an alternative method for root canal disinfection in endodontic treatments.

Cytotoxicity of modified nonequilibrium plasma with chlorhexidine digluconate on primary cultured human gingival fibroblasts.

The aim of this study was to investigate the cytotoxicity of modified nonequilibrium plasma with chlorhexidine digluconate (CHX) on human gingival fibroblasts (HGFs), and to evaluate the biosecurity of modified nonequilibrium plasma with 2% CHX as a new method of root canal treatment. Tissue samples taken from human gingiva were primarily cultured and passaged. Cells from passages 3-7 were used. HGFs were treated by modified nonequilibrium plasma with 2% CHX for 0 min (control group), 30 s, 1 min, 1.5 min, 3 min, 5 min, and 10 min, respectively, and then they were incubated for 0, 24, and 48 h. After that, cell counting kit-8 (CCK-8) assay was applied to analyze the cytotoxicity of modified nonequilibrium plasma with 2% CHX on HGFs. There was no significant difference between the 0 h group treated with the modified nonequilibrium plasma for 1 min and the control group (P>0.05). However, there were significant differences between all the other treated groups and the control group (P<0.05). When treated for 1.5 min or shorter, the cell viability was obviously increased; while treated for 3 min or longer, it was obviously reduced. Moreover, when successively cultured for 0, 24, and 48 h, cell viability was decreased at first and then increased in the 3-min-treated and 5-min-treated groups. The modified nonequilibrium plasma with 2% CHX was of no influence on cell viability in 1.5 min treatment, and it could be safely used on root canal treatment.

Enhanced bone regeneration with sequential delivery of basic fibroblast growth factor and sonic hedgehog.

BACKGROUND: Bone regeneration approaches that mimic the natural processes of bone repair have generated significant attention. We hypothesized that early delivery of an angiogenic factor combined with sustained exposure to an osteogenic factor would recapitulate the critical aspects of natural bone repair. MATERIALS AND METHODS: Basic fibroblast growth factor (bFGF) and sonic hedgehog (Shh) were constructed to the recombinant adeno-associated virus, respectively (rAAV2-tet-off-bFGF and rAAV2-Shh). The previous viral vector allowed for regulation of the bFGF expression by the addition of doxycycline, a tetracycline analogue. These two viral vectors were used to cotransduce bone marrow-derived mesenchymal stem cells (BMSCs). Several osteogenic markers such as core-binding factor a-1, alkaline phosphatase and osteocalcin were detected by quantitative real-time reverse transcriptase polymerase chain reaction. Meanwhile, protein expressions of transgenes were measured by western blot. Furthermore, these cotransduced BMSCs were seeded on ß-tricalcium phosphate (ß-TCP) granules and then were implanted into the calvarium defect in a rat model. A sample of 30 Sprague-Dawley rats was divided into six groups (n=5); an 8-mm critical-sized bone defect was made in calvarium of all subjects. Each group was treated with various transgenic BMSCs and ß-TCP composites; and the sixth group is the negative control which was implanted with nothing. At 4 weeks after treatment, the samples were evaluated with histological staining. RESULTS: The expression of osteogenic marker mRNA had an increased tendency after two genes transduction (p<0.05). In addition, dramatically enhanced regeneration of critical-sized calvarial defects was observed in the groups which were implanted with two transgenic BMSCs and ß-TCP composites. And in these experimental groups, bone areas and vascular densities were increased significantly (p<0.05) than other groups. CONCLUSION: Sequential delivery of angiogenic and osteogenic factors likely has a synergistic effect, mimicking the molecular events of natural bone regeneration.

[Effect of Bio-Oss loading with rAAV-BMP7 on regeneration of bone defects around dental implant].

OBJECTIVE: To evaluate in vivo gene delivery of Bio-Oss coated with adeno-associated virus-mediated human bone morphogenetic protein 7 (rAAV-BMP7/Bio-Oss) for bone regeneration around dental implants. METHODS: In vitro rAAV-BMP7 were constructed and compounded with Bio-Oss. In 6 male New Zealand rabbits, two hydroxyapatite (HA) coated titanium dental implants were placed respectively to each animal in the bilateral tibia metaphysis. Before implantation, a standardized gap (8 mm in width, 4 mm in depth) was created between the implant surface and the surrounding bone walls. Rabbits were randomly divided into three groups (group A, B, C). Gaps of group A were filled with rAAV-BMP7/Bio-Oss (n = 4), gaps of group B were filled with Bio-Oss alone (n = 4), and gaps of group C were filled with nothing (n = 4). The rabbits were sacrificed at 4 and 8 weeks respectively, and the sclerous tissue slices obtained, then histology and histomorphometric analysis were conducted. RESULTS: Histological and histomorphometric analysis revealed an enlarged bone-forming area in the bone defects of group A and B at 4 and 8 weeks after implantation. Greater bone-implant contact was achieved with rAAV-BMP7/Bio-Oss than with Bio-Oss alone and this difference was statistically significant (P < 0.05). CONCLUSION: rAAV-BMP7/Bio-Oss can induce a stronger peri-implant bone reaction and larger new bone formation than Bio-Oss alone in the treatment of bone defects adjacent to titanium dental implants.

[Effects of transforming growth factor-beta1 gene therapy on bone rarefaction around endosseous implant].

OBJECTIVE: To investigate the effects of transforming growth factor-beta1 (TGF-beta1) gene therapy on bone defect and bone rarefaction around endosseous implant. METHODS: The primary cultured bone marrow derived stroma cells (BMSCs) was transfected by plasmid pCDNA3.1(+) -TGF-beta1, and was adhered with polylactic-co-glycolic acid (PLGA) for constructing TGF-beta1 gene-modified artificial bone. The model of rats with placed titanium implants in the proximal metaphyses of the tibiae after ovariectomy was made. The TGF-beta1 gene-modified artificial bone (experimental group), BMSCs-PLGA compound artificial bone (control group) and nothing (blank control group) were placed in the bone defect around implant. The tibiae were examined by decalcified sections with immunohistochemical method and histological analysis methods at intervals of 4 and 8 weeks after implant surgery in order to detect the expression of TGF-beta1 in new bone adjacent to the implant and the healing of the bone defect around the implant. RESULTS: The expression level of TGF-beta1 of experimental group was higher than that of control group and blank control group at the 4th week. The histological analysis indicated that the gene-modified artificial bone had stronger osetogenic potential than others. CONCLUSION: TGF-beta1 gene-modified artificial bone promotes the repair of the bone defect around titanium implants in osteoporotic rats.