Alveolar ridge preservation of two-wall bone defects using mineralized dentin matrix: An experimental pre-clinical study.

OBJECTIVES: To study bone healing of two-wall bone defects after alveolar ridge preservation using mineralized dentin matrix. MATERIALS AND METHODS: After distal roots extraction of second and fourth premolars (P2, P4) on one lateral mandible in 12 beagles, two-wall bone defects (5 × 5 × 5 mm) were surgically created distally to the remaining mesial roots of P2 and P4. A total of 24 sites were randomly allocated to three groups (implant material- time of execution): mineralized dentin matrix (MDM)-3 m (MDM + collagen membrane; 3 months), MDM-6 m (MDM particles + collagen membrane; 6 months), and C-6 m (collagen membrane only; 6 months). Clinical, radiographic, digital, and histological examinations were performed 3 and 6 months after surgery. RESULTS: The bone healing in MDM groups were better compared to Control group (volume of bone regenerated in total: 25.12 mm3 vs. 13.30 mm3, p = .046; trabecular volume/total volume: 58.84% vs. 39.18%, p = .001; new bone formation rate: 44.13% vs. 31.88%, p = .047). Vertically, the radiological bone level of bone defect in MDM-6 m group was higher than that in C-6 m group (vertical height of bone defect: 1.55 mm vs. 2.74 mm, p = .018). Horizontally, no significant differences in buccolingual bone width were found between MDM and C groups at any time or at any level below the alveolar ridge. The percentages of remaining MDM were <1% in both MDM-3 m and MDM-6 m groups. CONCLUSIONS: MDM improved bone healing of two-wall bone defects and might be considered as a socket fill material used following tooth extraction.

Network meta-analysis of the treatment efficacy of different lasers for peri-implantitis.

The aim of this study was comparing different lasers with conventional non-surgical treatment (CNT) for the management of peri-implantitis, regarding probing depth (PD), plaque index (PLI), clinical attachment level (CAL), and sulcus bleeding index (SBI). Randomized controlled trials (RCTs) on different lasers and CNT for peri-implantitis were searched. Pairwise and network meta-analyses were performed to analyze the PD, PLI, CAL, and SBI outcomes. The risk of bias, evidence quality, statistical heterogeneity, and ranking probability were also evaluated. Eleven studies were included in this study, involving three types of lasers. Diode + CNT had significantly superior efficacy to CNT alone, regarding PD reduction, while Er:YAG + CNT had significantly superior efficacy than CNT in terms of the PLI, CAL, and SBI. The highest probability of being most effective for PD was diode + CNT (49%), while Er:YAG + CNT had the highest probability of improving the PLI, CAL, and SBI (66%, 53%, and 79%, respectively). Diode + CNT was significantly superior for PD management in peri-implantitis compared with CNT alone, while Er:YAG + CNT significantly improved the PLI, CAL, and SBI. Therefore, Er:YAG + CNT might be recommended methods considered for management of peri-implantitis.

Vitamin D and liver cancer risk: A meta-analysis of prospective studies.

BACKGROUND AND OBJECTIVES: The association between circulating vitamin D and liver cancer risk has been controversial on the basis of epidemiological studies. The aim of this study was to quantitatively evaluate this association with prospective studies. METHODS AND STUDY DESIGN: A systematic literature search was implemented in PubMed and Scopus databases up to June 2019. Using a random-effects model, the multivariate-adjusted relative risks (RRs) with corresponding 95% confidence interval (CI) were pooled for the highest versus lowest category. Trend estimation was conducted with a two-stage dose-response meta-analysis. RESULTS: Six independent prospective studies (992 liver cancer events and 60,811 participants) were included for data synthesis. The summary estimate showed that a higher circulating vitamin D was associated with lower risk of liver cancer (Summary RR=0.78; 95% CI: 0.63, 0.95; I2=53.6%, p=0.035). Dose-response analysis indicated that liver cancer was associated with 8% (95% CI: 0.89, 0.95) lower risk with a 10 nmol/L increment of circulating vitamin D concentration. CONCLUSIONS: The present study provides substantial evidence that a higher concentration of circulating vitamin D would have conferred protection against liver cancer.

Effect of peri-implant bone resorption on mechanical stress in the implant body: In vivo measured load-based finite element analysis.

BACKGROUND: Research on resolving implant fracture is still gaining attention as it can be a serious treatment failure outcome. The implant fracture is likely to occur due to increased stress in implant body associated with peri-implant bone resorption. OBJECTIVE: This study aimed to investigate the relationship between degree of peri-implant bone resorption and stress distribution in implant body by using finite element analysis (FEA). METHODS: The magnitude and direction of loads on implants at the mandibular molar region were measured with 3D piezoelectric force transducers in a patient during maximal voluntary clenching, grinding and tapping to obtain input for the FEA as the loading condition. Simplified finite element bone models were generated to simulate the six patterns of peri-implant bone resorption progression which the bone levels from implant platform were set at 0, 1, 2, 3, 4 and 5 mm. Three types of implants with different diameters (3.5, 4.0 and 5.0 mm), corresponding abutments and screws were created. FEA using the in vivo measured load was conducted to investigate how peri-implant bone loss affects stress distribution in the implant body. RESULTS: Loading condition affected stress distribution in the implant body. As bone resorption increased, von Mises stress in the implant body became larger, which was marked in smaller diameter implants, and this change was amply demonstrated when the bone resorption increased from 0 to 2 mm. CONCLUSION: The FEA demonstrated that as peri-implant bone loss increased, the magnitude of stress in the implant increased, especially in small diameter implants.

Comparison of technical, biological, and esthetic parameters of ceramic and metal-ceramic implant-supported fixed dental prostheses: A systematic review and meta-analysis.

STATEMENT OF PROBLEM: Differences between ceramic and metal-ceramic implant-supported fixed dental prostheses are unclear. PURPOSE: The purpose of this systematic review and meta-analysis was to compare the technical, biological, and esthetic complication rates of implant-supported ceramic and metal-ceramic restorations. MATERIAL AND METHODS: Six databases were searched to identify randomized controlled clinical trials (RCTs) and prospective and retrospective cohort studies of implant-supported fixed dental prostheses. The survival rate, marginal adaptation, marginal bone loss, pocket probing depth, crown color match, and mucosal discoloration of ceramic and metal-ceramic single crowns were assessed. For implant-supported fixed partial dental prostheses (FPDPs), only the survival rate was assessed. The risk of bias was assessed for individual studies and across studies by using the Cochrane guidelines, Newcastle-Ottawa scale, and funnel plots. RESULTS: Twenty studies were included in this meta-analysis. Ceramic and metal-ceramic implant-supported single crowns were compared in terms of the survival rate (OR=0.84 [0.32, 2.23], P=.730), marginal adaptation (mean difference [MD]=0.33 [0.19, 0.47], P<.001), marginal bone loss (MD=-0.03 [-0.07, 0.02], P=.260), pocket probing depth (MD=-0.07 [-0.14, 0.00], P=.060), crown color match (MD=-0.15 [-0.29, 0.00], P=.040), and mucosal discoloration (standardized mean difference [SMD]=-0.14 [-0.86, 0.58], P=.710). The survival rate of ceramic and metal-ceramic implant-supported FPDPs was also compared (odds ratio [OR]=1.92 [1.26, 2.94], P=.003). CONCLUSIONS: No significant difference was observed between ceramic and metal-ceramic implant-supported single crowns in terms of the survival rate, marginal bone loss, pocket probing depth, or mucosal discoloration. However, metal-ceramic single crowns had better marginal adaptation and poorer crown color match than did ceramic single crowns. In addition, current evidence indicates that metal-ceramic implant-supported FPDPs might have a higher survival rate than ceramic FPDPs.

Effect of Lasers on Dentine Hypersensitivity: Evidence From a Meta-analysis.

OBJECTIVES: The aim of the study was to evaluate the immediate and long-term desensitizing effect of lasers in reducing dentine hypersensitivity (DH) compared with negative controls. MATERIAL AND METHODS: Six databases were searched to identify relevant articles published up to June 8, 2018. Randomized controlled trials comparing lasers with placebo or no treatment control in adult patients who suffer from DH were included. The risk of bias was assessed according to the Cochrane guidelines, and the quality of the evidence was evaluated using the Grading of Recommendations Assessment, Development and Evaluation tool. Inverse-variance random effects meta-analyses of standardized mean differences and 95% confidence intervals were performed using the RevMan 5.3 software. RESULTS: Twenty-two randomized controlled trials were finally included in the meta-analysis, and 21 studies of these were conducted to analyze the immediate and long-term effects. All types of lasers had better immediate and long-term desensitizing effects on DH than negative controls. The quality of evidence of the included studies showed that lasers compared with negative controls had moderate-quality immediate and long-term effects on DH. The statistical heterogeneity of these comparisons was high, for which the result of I2 ranged from 90% to 98%. CONCLUSIONS: Our results indicate that all types of lasers had a better desensitizing effect on DH than negative controls, both in immediate and long term. Furthermore, more high-quality studies with a large sample size are needed to confirm our results (PROSPERO CRD42018102260).

The adhesive strength and initial viscosity of denture adhesives.

OBJECTIVE: To examine the initial viscosity and adhesive strength of modern denture adhesives in vitro. MATERIALS AND METHODS: Three cream-type denture adhesives (Poligrip S, Corect Cream, Liodent Cream; PGS, CRC, LDC) and three powder-type denture adhesives (Poligrip Powder, New Faston, Zanfton; PGP, FSN, ZFN) were used in this study. The initial viscosity was measured using a controlled-stress rheometer. The adhesive strength was measured according to ISO-10873 recommended procedures. All data were analyzed independently by one-way analysis of variance combined with a Student-Newman-Keuls multiple comparison test at a 5% level of significance. RESULTS: The initial viscosity of all the cream-type denture adhesives was lower than the powder-type adhesives. Before immersion in water, all the powder-type adhesives exhibited higher adhesive strength than the cream-type adhesives. However, the adhesive strength of cream-type denture adhesives increased significantly and exceeded the powder-type denture adhesives after immersion in water. For powder-type adhesives, the adhesive strength significantly decreased after immersion in water for 60 min, while the adhesive strength of the cream-type adhesives significantly decreased after immersion in water for 180 min. CONCLUSION: Cream-type denture adhesives have lower initial viscosity and higher adhesive strength than powder type adhesives, which may offer better manipulation properties and greater efficacy during application.

[Study on the properties of self-adhering flowable composite].

OBJECTIVE: This study was designed to investigate the properties of self-adhering flowable composite by comparison with self-etching adhesive and traditional composite. Moreover, the effect of additional etching process on the bond strength of dentin was investigated. METHODS: Totally 90 bovine incisors were prepared to expose the dentin, and then divided into three groups (Group A, Group B and Group C). A, B and C were treated with flowable composite, flowable composite and self-etching adhesive, traditional composite and self-etching adhesive respectively. These groups were further divided into two subgroups, without additional etching process(i.e. A1, B1 and C1) and with additional etching process (i.e. A2, B2 and C2). The bond strength of those samples was measured and the results were analyzed with a one-way ANOVA. RESULTS: The shear bond strength of A1 [(3.39±1.71 ) MPa] was lower than B1 [(21.58±4.50) MPa],and there is significant difference (P<0.05) between them. There is no significant difference (P>0.05) between B1 and C1 [(19.31±6.79) MPa]. After additional etching process, the shear bond strength of A2 [(6.75±3.54) MPa] was higher than A1. As for self-etching adhesive, the shear bond strength of B2 [(16.56±7.39) MPa] was lower than B1 (P<0.05) and C2 [(11.31±5.54) MPa] was lower than C1 (P<0.05). CONCLUSION: The bond strength of self-adhering flowable composite was lower than that of flowable composite with self-etching adhesive. There was no significant difference between bond strength of flowable composite with self-etching adhesive and traditional composite with self-etching adhesive. However, the additional etching process would decrease bond strength of self-etching adhesive and increase the coefficient of variation of measured results.

Feasibility and Efficacy of a Degradable Magnesium-Alloy GBR Membrane for Bone Augmentation in a Distal Bone-Defect Model in Beagle Dogs.

We explored the feasibility and efficacy of a degradable magnesium (Mg) alloy guided bone regeneration (GBR) in the treatment of bone defects after tooth extraction. A GBR membrane (MAR-Gide (MG)) was used to treat a mandibular second molar (M2M)-distal bone defect (DBD). In eight beagle dogs, bilateral mandibular second and fourth premolars were hemi-sected. The distal roots were removed to create a two-wall bony defect of dimension 5 mm × 5 mm × 5 mm to simulate M2M-DBD. Thirty-two bone defects were assigned randomly into four groups according to GBR membranes (MG and Bio-Gide (BG)) applied and the time of killing (3 months and 6 months after surgery). The osteogenesis of bone defects and MG degradation were analyzed using micro-CT, histology (staining, tartrate-resistant acid phosphatase), and inductively coupled plasma mass spectrometry. MG did not increase the prevalence of infection, wound dehiscence, or subcutaneous emphysema compared with those using BG. Trabecular volume/total volume at 3 months (63.71 ± 10.4% vs. 59.97 ± 8.94%) was significantly higher in the group MG than that in the group BG. Implanted MG was degraded completely within 3 months, and "island-shaped" new bone was found near MG degradation products. A significant difference was not found in vertical bone height or percent of new bone formation (45.44 ± 12.28% vs. 43.49 ± 7.12%) between the groups. The concentration of rare-earth elements in mandibular lymph nodes of the group MG was significantly higher than that of the group BG (P ≤ 0.017) but did not lead to histopathological changes. In summary, MG exhibited good biocompatibility and clinical applicability compared with BG in vivo. The osteogenic effect of MG could be enhanced by regulating the degradation rate of Mg-alloy.

Polymerization characteristics, flexural modulus and microleakage evaluation of silorane-based and methacrylate-based composites.

PURPOSE: To compare the behavior of a new low-shrinkage silorane-based composite (P90) with two conventional methacrylate-based composites, in terms of polymerization shrinkage, polymerization stress, gel point, flexural modulus and microleakage. METHODS: The materials tested were P90 (3M ESPE), AP-X (Kuraray), Quixfil (Dentsply). Polymerization shrinkage was measured using the Accuvol method. Polymerization stress was assessed using a stress-strain analyzer. Polymerization shrinkage (%) and force (N) were continuously recorded for 300 seconds. Polymerization shrinkage and stress after 300 seconds and gel point were recorded. Flexural modulus was obtained by three-point bending. A laboratory microleakage test was performed. Class V cavities prepared on labial surfaces of 70 freshly extracted human teeth were randomly assigned to the seven groups (N=10): P90/PSA (P90 System Adhesive), AP-X/CBA (Clearfil SE Bond Adhesive), Quixfil/XBA (XP Bond Adhesive), P90/CBA, P90/XBA, AP-X/PSA, Quixfil/PSA. The teeth were immersed in 1% basic fuchsin dye for 24 hours at room temperature. All teeth were cut in a labial-lingual direction and the penetration of dye along the wall of cavities was observed under a stereoscopic light microscope. Statistical analysis was performed with one-way ANOVA, Kruskal-Wallis ANOVA test and post hoc tests (P< 0.05). RESULTS: The low-shrinkage silorane-based composite (P90) exhibited significantly lower polymerization shrinkage, polymerization stress, flexural modulus and a later gel point than the conventional methacrylate-based composites. In the microleakage test, P90/PSA, AP-X/CBA, AP-X/PSA demonstrated the lowest microleakage scores without a significant difference among them (P> 0.05). Quixfil/XPA exhibited the highest microleakage scores.

Effect of amylase activity on mechanical properties of dental composite resin.

The purpose of this study was to investigate the effect of amylase activity on the mechanical properties of three dental composite resin (Filtek Z350; Filtek Z250 and Polofil Supra). The specimens were immersed in amylase solution at four different activities (25, 50, 100 and 200 KIU/L) with an artificial saliva solution (AS) as a control. The flexural strength (FS) and elastic modulus (EM) were determined in a three-point bending test after immersion for periods up to 12 months. In addition, surface roughness and surface morphology also determined. The FS of Filtek Z350 reaching the lowest level of 67.86 MPa after AS immersion for one year. There was a general trend for FS to decrease following immersion in AS for all the tested materials. However, the amylase groups did not undergo a significant decrease in FS and EM, and there was a slight increase in FS and EM for Polofil Supra.

The Dynamic Viscoelasticity of Dental Soft Polymer Material Containing Citrate Ester-Based Plasticizers.

The aim of this study was to investigate the dynamic viscoelasticity of dental soft polymer material containing citrate ester-based plasticizers. Three kinds of citrate ester-based plasticizer (Citroflex® C-2: TEC, Citroflex® A-2: ATEC, and Citroflex® A-4: ATBC), with the combination of 5 wt% ethyl alcohol, were used as the liquid phase. The dynamic viscoelastic properties of nine ethyl methacrylate polymers: (A, B, C, D, E, F, G, H, and I) were immersed in 37 °C distilled water for 0, 1, 3, 7, 14 and 30 days, respectively. The dynamic viscoelastic properties were measured at 37 °C with an automatic dynamic mechanical analyzer. The shear storage modulus (G'), shear loss modulus (G″), and loss tangent (tan δ) were determined at 1 Hz. These parameters were statistically analyzed by two-way and one-way ANOVA and Tukey's multiple comparison test at a predetermined significance level of 0.05. A significant difference was found among the materials in terms of the dynamic viscoelasticity. The materials containing citrate ester-based plasticizer ATBC showed the most stable dynamic viscoelasticity. Considering the limitations of this study, the results suggest that the inclusion of citrate ester-based plasticizer can improve the durability of dental soft polymer materials.

Network meta-analysis on the effect of desensitizing toothpastes on dentine hypersensitivity.

OBJECTIVES: This network meta-analysis compares different desensitizing toothpastes and placebo in terms of their effects on dentine hypersensitivity (DH) at 2, 4, and 8 weeks. MATERIALS AND METHODS: A systematic electronic literature search of four databases, and a manual search, were performed to identify randomized controlled trials (RCTs) on different desensitizing toothpastes for the treatment of DH. Pair-wise and network meta-analyses were performed to analyze the desensitization effect at 2, 4, and 8 weeks. The risk of bias was assessed based on the Cochrane guidelines and funnel plots. Statistical heterogeneity, inconsistencies, and ranking probability were also evaluated. RESULTS: A total of 30 RCTs were included in the network meta-analysis, which included eight desensitizing toothpastes. There was no significant difference in the effect among calcium sodium phosphosilicate-containing (CSPS), potassium-containing (K) and strontium-containing (Sr) toothpastes. In addition, there was no significant difference between fluoride (F) and placebo. The desensitizing toothpaste with the highest probability of being the most effective treatment for DH was nano-hydroxyapatite (n-HA) at 2 and 4 weeks (60% and 67%, respectively), and Ar at 8 weeks (54%). CONCLUSIONS: No significant difference was detected in desensitizing effects among CSPS, K and Sr toothpastes. In addition, there was no significant difference between F and placebo, K and placebo. Furthermore, a significant placebo effect on DH was found in this study. Moreover, n-HA toothpastes may be the best desensitizing toothpastes for treatment of DH, followed by Ar toothpaste. CLINICAL SIGNIFICANCE: Based on the results of present network meta-analysis, n-HA containing toothpastes might be a recommended desensitizing toothpastes considering the treatment of DH. PROSPERO registration number: CRD42019117710.

Characterization and transferability of microsatellites for Gentiana lawrencei var. farreri (Gentianaceae).

PREMISE OF THE STUDY: Microsatellite markers were developed for a medicinal herb, Gentiana lawrencei var. farreri (Gentianaceae), for the future assessment of population genetic structure and potential hybridization events with related taxa. METHODS AND RESULTS: Using the 454 FLX+ sequencing platform, we obtained 81,717 clean reads with an average length of 291 bp. A total of 3031 primer pairs were designed, and 96 were selected for validation. A set of 20 fluorescently labeled primer pairs was further selected and screened for polymorphisms in three G. lawrencei var. farreri populations and one G. veitchiorum population. Among the four populations, the average number of alleles per locus was 15.2. Finally, a set of 17 unlinked loci were determined to be in Hardy-Weinberg equilibrium after two linked loci were removed. CONCLUSIONS: The identified simple sequence repeat markers will be useful for genetic diversity and evolution studies in G. lawrencei var. farreri and related taxa.

The effect of crude drugs on the angiogenic property and dynamic viscoelasticity of PEMA-based soft polymer materials.

This study aimed to determine the effect of crude drugs on the dynamic viscoelasticity and angiogenic property of soft polymer materials, in vitro. Two kinds of polyethyl methacrylates, and crude drugs (Astragalus membranaceus Bunge [HQ] and Salvia miltiorrhiza Bunge [DS]) were used in their powdered forms. And, acetyl tributyl citrate and ethyl alcohol were used in the liquid form. The dynamic viscoelasticity of each specimen was measured after 0, 1, 3, 7, 14 and 28 days of immersion in distilled water. The CellPlayer angiogenesis PrimeKit assay was used to test angiogenesis. Significant differences in dynamic viscoelasticity were observed among the materials. Specimens containing 1 wt% HQ showed higher angiogenic activity than those containing 5 wt% and 10 wt% HQ, and DS. Our results suggest that the addition of low amounts of crude drugs to soft polymer materials may promote angiogenesis in human tissues.

A novel method of surface modification by electrochemical deoxidation: Effect on surface characteristics and initial bioactivity of zirconia.

The aim of this study was to investigate and compare the surface characteristics and initial bioactivity of ceria-stabilized zirconia/alumina nanocomposite (NANOZR) with those of yttria-stabilized zirconia (3Y-TZP) and pure titanium (CpTi) following the use of three surface modification methods; polishing, sandblasting/acid-etching (SB-E) and electrochemical deoxidation (ECD). Physical properties including surface morphology, chemical composition, X-ray diffraction, surface wettability, surface roughness, and hardness were measured. Osteoblast-like MC3T3-E1 cells were used to examine cell morphology and attachment to the surfaces of the materials. ECD treated NANOZR (NANOZR-E) showed a well-arranged, self-organized microporous surface structure with significantly low contact angles when compared with the other specimens (p < 0.05). NANOZR-E also demonstrated a slight decrease in monoclinic phase content (-4.4 wt %). The morphology and attachment of MC3T3-E1 cells on NANOZR-E were similar to those on polished and SBE-treated CpTi surfaces. Higher cell affinity was observed on NANOZR-E when compared with ECD treated 3Y-TZP. The findings of this study indicate the effectiveness of the novel technique, ECD, in the formation of a microporous surface on NANOZR when compared with both CpTi and 3Y-TZP. Moreover, this method also appears to improve the biological activity of NANOZR during the initial stage. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2641-2652, 2017.

StPBS2, a MAPK kinase gene, is involved in determining hyphal morphology, cell wall development, hypertonic stress reaction as well as the production of secondary metabolites in Northern Corn Leaf Blight pathogen Setosphaeria turcica.

Mitogen activated protein kinase kinase (MAPKK) is a crucial component in the MAPK signaling pathway. However, the functions of MAPKKs in foliar pathogens remain poorly understood. In the current study, a MAPKK gene designated as StPBS2 was cloned from Setosphaeria turcica and the functions of this gene were investigated by RNAi technology. Four independent StPBS2 gene silence transformants with different efficiencies were confirmed by real time PCR. Compared to the wild type strain (WT), these transformants showed decreased colony growth, shortened hyphae cell length, broadened cell width and an obvious reduction in conidium yield. Moreover, the cell wall of the transformants was thicker and they were also more sensitive to substances that interfere with cell wall biosynthesis than WT. Additionally, the transformants displayed higher sensitivity to hypertonic stress than WT and the sensitivity was associated with the level of silencing of StPBS2. They were also resistant to the fungicides iprodione, procymidone and fludioxonil, to which WT almost completely sensitive. The transformants produced more red secondary metabolites than WT and the production was enhanced with increasing silencing level and increased glucose content in PDA medium. Our results suggest that StPBS2 is involved in morphogenesis, condiogenesis, cell wall development, hypertonic stress reaction and resistance to fungicides, as well as in the biosynthesis of secondary metabolites in S. turcica.

Biomechanical and histological evaluation of the osseointegration capacity of two types of zirconia implant.

The purpose of this study was to evaluate the biomechanical and histological behavior of a ceria-stabilized zirconia-alumina nanocomposite (NanoZr) in comparison with that of 3 mol% yttria-stabilized tetragonal zirconia polycrystalline (3Y-TZP) in Sprague Dawley rats. Cylindrical NanoZr and 3Y-TZP implants (diameter 1 mm, length 2 mm) were used. Implant-surface morphology and surface roughness were determined by scanning white-light interferometry and scanning electron microscopy, respectively. The cylindrical zirconia implants were placed at the distal edge of the femur of Sprague Dawley rats. At weeks 2, 4, and 8, the interfacial shear strength between implant and bone was measured by push-in test. Histological analysis was performed using hard-tissue sections. Bone-implant contact (BIC), the thickness of new bone around the implant within the bone marrow area, and osteoclast numbers were evaluated. The average surface roughness of 3Y-TZP (Sa 0.788 µm) was significantly higher than that of NanoZr (Sa 0.559 µm). The shear strengths of 3Y-TZP and NanoZr were similar at 2 weeks, but at 4 and 8 weeks the shear strength of NanoZr was higher than that of 3Y-TZP. The average BIC values within the bone marrow area for 3Y-TZP and NanoZr were 25.26% and 31.51% at 2 weeks, 46.78% and 38% at 4 weeks, and 47.88% and 56.81% at 8 weeks, respectively. The average BIC values within the cortical area were 38.86% and 58.42% at 2 weeks, 66.82% and 57.74% at 4 weeks, and 79.91% and 78.97% at 8 weeks, respectively. The mean BIC value did not differ significantly between the two zirconia materials at any time point. The NanoZr implants were biocompatible, capable of establishing close BIC, and may be preferred for metal-free dental implants.

[Analysis and mapping of a rice repeated sequence].

A repeated sequence with a length of 560 bp, termed as DH17, was obtained during PCR amplification of rice NBS-LRR homologues. A repeated unit of 352 bp in the DH17 fragment was revealed through sequence analysis and comparison, which has a high homology with the known sequences of OS48 and TrsA, and belongs to the same repeat family. Southern hybridization displayed that there are higher DH17 copies in the genome of an indica variety, ZYQ8,than that in the genome of japonica variety, JX17. The tandom repeated DH17 sequence was mapped on the long arm end of chromosome 12 through RFLP analysis of a double haploid population derived from ZYQ8 and JX17 using DH17 as a probe.

The surface characterization and bioactivity of NANOZR in vitro.

The purpose of this study was to evaluate the surface characterization and bioactivity of ceria-stabilized zirconia/alumina nanocomposite (NANOZR) in comparison to yttria-stabilized zirconia (3Y-TZP) and pure titanium (CpTi). Three-dimension surface morphology, surface wettability, bovine serum albumin adsorption rate, cell morphology, cell proliferation and ALP activity of three tested materials were measured. There were no significant differences in surface roughness, contact angle among the three materials. The ALP expression of NANOZR was higher than CpTi and 3Y-TZP at 14 and 21 days although bovine serum albumin adsorption rate, cell morphology; and cell proliferation was not different among the three materials. These results suggest that the three test materials basically had similar surface characterization and bioactivity. Within the limitations of this study, our results show that the three test materials were biologically similar bio-inert materials.