经微弧氧化钛铌锆锡合金的生物安全性评价

目的：评价低弹性模量钛铌锆锡合金（TNZS）表面应用微弧氧化技术进行改性后的生物安全性。方法：参照ISO7405-1997（E）/GB16886-1997最新标准,对该材料分别进行细胞毒性试验、溶血试验、口腔黏膜刺激试验、短期全身毒性试验。结果：体内外生物学试验结果表明：细胞毒性试验显示TNZS合金经微弧氧化处理后无细胞毒性;溶血率小于5%,有良好的血液相容性;口腔黏膜刺激试验未见异常组织学反应;短期全身毒性试验显示无明显短期全身毒性。结论：钛铌锆锡合金经微弧氧化技术改性后,显示了良好的生物安全性。     

PLGA/HA支架材料生物相容性的动物实验研究

目的:通过动物实验评价新型多孔聚乳酸乙醇酸/羟基磷灰石(polyaiticglycolic acid/hydroxyapatite,PLGA/HA)支架材料的生物相容性。方法:分别将5%和10%HA掺量的PLGA/HA支架材料注射到昆明小鼠腹腔内、植入到新西兰大白兔体内,选择全身毒性试验、亚急性毒性试验、血液相容性试验、肌肉刺激试验等,对其生物相容性进行评价。结果:全身急慢性毒性试验显示材料种植到小鼠及兔子体内后,动物一般情况良好,2周后体重、红细胞计数、白细胞计数等生理参数未见明显变化;实验显示两种材料对兔混合血浆凝血功能无影响;溶血试验结果显示5%和10%的PLGA/HA的溶血率分别为2.67%和3.62%,均小于5%,完全符合医用材料对溶血试验的要求;肌肉刺激试验结果显示两种材料埋植后局部未见红肿,4周时部分PLGA/HA材料开始降解,降解部分有大量的纤维结缔组织生长;HE染色结果显示PLGA/HA基本不存在抗原性,植入机体4周后,材料周围未见明显炎症细胞浸润。结论:5%和10%HA掺量的PLGA/HA均具有良好的生物相容性和体内安全性。     

以牛心包为来源的天然衍生引导骨组织再生膜制备方法的实验研究

目的:探索天然牛心包脱细胞和交联处理的理想方法。方法:用胰酶去垢剂法(I)、胰酶核酸酶法(II)、胰酶去垢剂+核酸酶联合法(III)、 冻融去污剂法(IV)、冻融核酸酶法(V)、冻融去污剂+核酸酶联合法(VI)进行脱细胞和交联处理,采用光镜和SEM、细胞毒性实验、机械性能测定、细胞趋化性实验评估处理效果,筛选出理想的脱细胞和交联方法。结果:冻融去污剂+核酸酶联合法是理想的脱细胞方法。京尼平交联法是理想的交联方法。结论:冻融去污剂+核酸酶联合法制备的脱细胞牛心包再采用京尼平交联法可制备出理想的GBR膜材料。     

阳极氧化后新型钛铌锆锡合金的生物安全性评价

目的：评价新型医用钛合金Ti-24Nb-4Zr-7．9Sn（TNZS）表面应用阳极氧化（Anodicoxidation，AD）技术进行改性后的生物安全性。方法：按照国标GB16886．5—1997。GB16886．4～1997。GB16886．10—2005、医药行业标准YY—T0279—1995、YY—T0244—1996所规定的方法，分别进行细胞毒性试验、溶血试验、口腔黏膜刺激试验、短期全身毒性试验。结果：细胞毒性试验结果显示TNZS钛合金经阳极氧化处理后无细胞毒性，溶血试验结果溶血率小于5％，有良好的血液相容性，口腔黏膜刺激试验结果显示对黏膜无刺激性，短期全身毒性试验显示无短期全身毒性。结论：新型的钛铌锆锡合金经阳极氧化技术改性后，显示了良好的生物安全性。     

丝素蛋白多孔支架用于口腔软组织增厚的初步研究

目的 通过体内实验探究3种不同浓度的丝素蛋白多孔支架在口腔软组织增厚应用中的可行性。方法采用冷冻干燥及甲醇增强法制备3种不同浓度：质量分数为1%(SF1组)、3%(SF3组)、5%(SF5组)的丝素蛋白支架,通过扫描电子显微镜（SEM）、傅里叶转换红外光谱（FTIR）、X射线衍射（XRD）、热重分析（DSC）对支架进行表征分析,并测定各组支架的孔径、孔隙率及体外降解速率。将3组支架材料（实验侧）与胶原基质（对照侧）分别植入新西兰大白兔两侧口腔黏膜下,比较其术前、术后3个月黏膜厚度的变化,通过组织苏木精-伊红（HE）染色法、Masson染色法对比观察各组材料的体内代谢及再生效果。结果 SEM显示：3组支架材料都是相互交联的多孔结构;XRD及FTIR表明：3组支架均以较稳定的SilkⅡ型结构为主,在体外降解较慢;其中SF3组的孔径最大（133.40μm±22.85μm）,孔隙率适中（90.05%±6.68%）。体内实验结果表明：除了SF1组因空间维持不足导致增厚效果类似于对照侧以外,SF3及SF5组的空间维持稳定、增厚效果明显优于对照侧;但不同于SF5组诱发了明显的炎症,SF3组体内降解较...     

快速成型技术构建聚己内酯支架作为骨支架材料的研究

目的：运用快速成型技术（RP）构建聚己内酯（PCL）支架,检测其生物相容性,探讨成为组织工程骨支架的潜力。方法：以聚己内酯为原料利用熔融沉积成型法（FDM）制备无孔隙及孔径300μm、500μm 3种PCL支架,比重瓶法测孔隙率。利用MTT法检测支架材料对细胞增殖的影响。倒置荧光显微镜、扫描电子显微镜观察聚己内酯支架上的细胞粘附情况及细胞形态。结果：肉眼观察可见300μm及500μm孔径支架材料孔隙大小均匀,排列规整,层次分明,两种孔径支架都具有良好的孔隙连通率。MTT检测结果显示1d、2d、3d各时间点均无明显细胞毒性,细胞毒性为1级。荧光倒置显微镜下观察发现细胞粘附数量由无孔隙组、500μm孔径组、300μm孔径组依次增加。扫描电子显微镜下观察细胞紧密粘附于支架。结论：用快速成型技术制备的聚己内酯支架具有较高的孔隙率,孔隙之间连通率良好,生物相容性良好,细胞粘附良好,有望成为骨组织工程支架。     

齿科修复用Zr-Cu-AL-Ag合金的生物安全性评价

目的：评价新型口腔修复用Zr-Cu-AL-Ag合金的生物安全性.方法：对Zr-Cu-AL-Ag合金进行细胞毒性试验、血液相容性试验以及急性全身毒性试验.结果：细胞毒性试验显示Zr-Cu-AL-Ag合金细胞毒性反应为0级,无细胞毒性;血液相容性试验Zr-Cu-AL-Ag合金溶血率数值小于5％,达到了生物材料对溶血率的要求.全身毒性试验显示无明显短期全身毒性.结论：Zr-Cu-AL-Ag合金拥有良好的细胞相容性、良好的血液相容性并且无急性全身毒性,可以初步满足其作为口腔植入材料的基本要求.     

可吸收内固定材料L/DL-聚乳酸的体外生物学评价

目的：对自行研制的医用可吸收内固定材料Ｌ／ＤＬ－聚乳酸〔Ｐ（Ｌ／ＤＬ）ＬＡ〕的体外生物相容性进行评价。方法：使用细胞毒性试验、溶血试验和热原试验等３种方法。结果：①培养的Ｌ９２９小鼠成纤维细胞经Ｐ（Ｌ／ＤＬ）ＬＡ浸提液或降解液处理后形态良好,增殖旺盛,材料毒性评级为０￣１级;②溶血率为２．６５％（小于５％）,符合溶血试验标准要求;③无热原反应。结论：Ｐ（Ｌ／ＤＬ）ＬＡ具有良好的生物相容性。     

新型眩彩复合体生物安全性初步评价

目的：评价新型眩彩复合体（Twinky Star）的生物安全性。方法：通过细胞毒性试验（MTT法）、溶血试验、短期全身毒性试验（经口途径）,评价新型眩彩复合体（Twinky Star）的生物安全性。结果：细胞毒性试验显示该材料无细胞毒性;材料溶血率为1.76%,小于中华人民共和国医药行业标准（YY）规定的5%,认为该材料未引发溶血现象,对凝血功能无影响;短期全身毒性实验的受试小鼠无一死亡,其体重相对增长率和食物利用率与对照组无统计学差异（P〉0.05）,心、肾、肝等重要器官肉眼观察无异常改变,其组织切片未见病理改变。结论：新型眩彩复合体（Twinky Star）具有较好的生物安全性。     

EDC交联离子化胶原支架材料的生物学表征

目的:研究EDC交联对离子化胶原支架材料的理化性能的影响。方法:采用侧链修饰结合碳化二亚胺交联改性技术制备实验使用的离子化胶原材料:天然胶原、甲基化胶原、琥珀酰化胶原,通过扫描电境、差示扫描热计、傅里叶变换红外光谱仪和体外酶降解实验分析对胶原材料交联前后的结构与性能进行研究。结果:侧链修饰改变了胶原的表面电荷性质,碳化二亚胺交联提高了天然胶原、甲基化胶原的孔径、孔隙率(P<0.05)、变性温度、抗酶降解能力(P<0.05),改变了其化学结构;而对琥珀酰化胶原的孔径、孔隙率、化学结构无明显影响,且降低了其变性温度和抗酶降解能力(P<0.05)。结论:EDC交联可显著改善离子化胶原支架材料的物理化学性能,为其在牙周组织再生中的初步应用提供了实验基础。     

Fabrication and characterization of a novel injectable human amniotic membrane hydrogel for dentin-pulp complex regeneration

ObjectiveInjectable biomaterials that can completely fill the root canals and provide an appropriate environment will have potential application for pulp regeneration in endodontics. This study aimed to fabricate and characterize a novel injectable human amniotic membrane (HAM) hydrogel scaffold crosslinked with genipin, enabling the proliferation of Dental Pulp Stem Cells (DPSCs) and optimizing pulp regeneration.MethodsHAM extracellular matrix (ECM) hydrogels (15, 22.5, and 30 mg/ml) crosslinked with different genipin concentrations (0, 0.1, 0.5, 1, 5, and 10 mM) were evaluated for mechanical properties, tooth discoloration, cell viability, and proliferation of DPSCs. The hydrogels were subcutaneously injected in rats to assess their immunogenicity. The hydrogels were applied in a root canal model and subcutaneously implanted in rats to determine their regenerative potential for eight weeks, and histological and immunostaining analyses were performed.ResultsHydrogels crosslinked with low genipin concentration demonstrated low tooth discoloration, but 0.1 mM genipin crosslinked hydrogels were excluded due to their unfavourable mechanical properties. The degradation ratio was lower in hydrogels crosslinked with 0.5 mM genipin. The 30 mg/ml-0.5 mM crosslinked hydrogel exhibited a microporous structure, and the modulus of elasticity was 1200 PA. In vitro, cell culture showed maximum viability and proliferation in 30 mg/ml-0.5 mM crosslinked hydrogel. All groups elicited minimum immunological responses, and highly vascularized pulp-like tissue was formed in human tooth roots in both groups with/without DPSCs.SignificanceGenipin crosslinking improved the biodegradability of injectable HAM hydrogels and conferred higher biocompatibility. Hydrogels encapsulated with DPSCs can support stem cell viability and proliferation. In addition, highly vascularized pulp-like tissue formation by this biomaterial displayed potential for pulp regeneration.     

Development and characterization of a new chitosan-based scaffold associated with gelatin,microparticulate dentin and genipin for endodontic regeneration

ObjectiveAn ideal scaffold for endodontic regeneration should allow the predictableness of the new tissue organization and limit the negative impact of residual bacteria. Therefore, composition and functionalization of the scaffold play an important role in tissue bioengineering. The objective of this study was to assess the morphological, physicochemical, biological and antimicrobial properties of a new solid chitosan-based scaffold associated with gelatin, microparticulate dentin and genipin.MethodsScaffolds based on chitosan (Ch); chitosan associated with gelatin and genipin (ChGG); and chitosan associated with gelatin, microparticulate dentin and genipin (ChGDG) were prepared by using the freeze-drying method. The morphology of the scaffolds was analyzed by scanning electron microscopy (SEM). The physicochemical properties were assessed for biodegradation, swelling and total released proteins. The biological aspects of the scaffolds were assessed using human cells from the apical papilla (hCAPs). Cell morphology and adhesion to the scaffolds were evaluated by SEM, cytotoxicity and cell proliferation by MTT reduction-assay. Cell differentiation in scaffolds was assessed by using alizarin red assay. The antimicrobial effect of the scaffolds was evaluated by using the bacterial culture method, and bacterial adhesion to the scaffolds was observed by SEM.ResultsAll the scaffolds presented porous structures. The ChCDG had more protein release, adhesion, proliferation and differentiation of hCAPs, and bacteriostatic effect on Enterococcus faecalis than Ch and ChGG (p < 0.05).SignificanceThe chitosan associated with gelatin, microparticulate dentin and genipin has morphological, physicochemical, biological and antibacterial characteristics suitable for their potential use as scaffold in regenerative endodontics.     

Bracket bond strength comparison between new unfilled experimental self-etching primer adhesive and conventional filled adhesives

Objective:To determine if a new unfilled experimental self-etching primer (SEP) adhesive system (SBP-40TX + C&B Metabond) that incorporates a methyl methacrylate–based 4-META/TBB (4-methacryloxyethyl trimellitate anhydride tri-n-butyl borane) resin can provide adequate shear bond strength (SBS) when used for bonding orthodontic brackets.Methods and Materials:Forty-eight human maxillary premolars were randomly divided into three groups of 16 specimens each. Brackets were bonded with three bonding systems. A filled Bis-GMA/TEGDM (triethylene glycol dimethacrylate)–based SEP adhesive system (Transbond Plus) and an unfilled conventional etch-and-rinse adhesive system (C&B Metabond) were used for comparison. The SBS for each sample was examined with a universal testing machine, and the Adhesive Remnant Index score was calculated. Enamel surfaces after conditioning were examined using a scanning electron microscope. Data were compared by one-way analysis of variance and a χ² test.Results:The experimental SEP showed a milder etching pattern than Transbond Plus SEP. No statistically significant differences in the mean SBS were found between the specimens bonded with the unfilled experimental SEP adhesive system (10.0 MPa) and the filled SEP adhesive system (8.7 MPa). The unfilled experimental SEP adhesive system showed less residual adhesive than the filled SEP adhesive system.Conclusions:The unfilled experimental SEP adhesive system showed a clinically sufficient SBS that was equivalent to the filled SEP adhesive system.     

Childhood socioeconomic position, adult sense of coherence and tooth retention

Bernabé E, Watt RG, Sheiham A, Suominen AL, Vehkalahti MM, Nordblad A, Uutela A, Kivimäki M, Tsakos G. Childhood socioeconomic position, adult sense of coherence and tooth retention. Community Dent Oral Epidemiol 2012; 40: 46–52. © 2011 John Wiley & Sons A/S Abstract – Objective: To explore the role of sense of coherence (SOC) as a mediator in the relationship between childhood socioeconomic position (SEP) and tooth retention in adulthood. Methods: Data from 5401 dentate adults aged 30 and over who participated in the nationally representative Finnish Health 2000 Survey were analysed. Participants provided information on demographic characteristics (sex and age), childhood SEP (parental education), adulthood SEP (years of education and household income), the SOC scale and oral health‐related behaviours (dental attendance, toothbrushing frequency, sugar intake frequency and daily smoking). They also had a clinical oral health examination. Structural equation modelling was used to test a model including adulthood SEP, SOC and oral health‐related behaviours as mediators of the relationship between childhood SEP and tooth retention. Multigroup comparison was also conducted to test the hypothesized model within each sex and age group (<45 years, 45–59 years and 60+ years). Results: The relationship between childhood SEP and tooth retention in adulthood was to a large extent mediated by adulthood SEP and to a much lesser extent by SOC. There was only a weak association between childhood SEP and adult SOC, but favourable oral health‐related behaviours appeared to link a strong SOC with greater tooth retention. The model was invariant across sexes and age groups. Conclusions: SOC is associated with tooth retention through oral health‐related behaviours, but contributes little to the relationship between childhood SEP and tooth retention.     

Influence of self-etchant application time on bracket shear bond strength

OBJECTIVE: To determine the influence of self-etching primer (SEP) application time on the shear bond strength of orthodontic brackets. MATERIALS AND METHODS: Forty human molars were cleaned, mounted, and randomly divided into two groups. The same SEP, adhesive, and brackets were used in both groups. Twenty teeth were conditioned following the manufacturers' recommendations by rubbing the SEP on the enamel surface for 3 to 5 seconds. The remaining 20 teeth were conditioned using the same SEP, but the application time was increased to 15 seconds. The teeth were debonded within half an hour following initial bonding using a universal testing machine. After debonding, the amount of residual adhesive remaining on the tooth was determined. Student's t-test was used to compare the shear bond strength (SBS) of the two groups, and the chi2 test was used to compare the Adhesive Remnant Index (ARI) scores for the two adhesive systems. RESULTS: The mean SBS of the brackets bonded to the teeth subjected to the SEP for 3 to 5 seconds was 8.0+/-4.6 MPa and was not significantly different (t=-0.69, P=.494) from the SBS of the brackets bonded using a 15-second SEP application time (x=8.9+/-3.4 MPa). The comparisons of the ARI scores between the two groups (chi2=2.16) indicated that bracket failure mode was not significantly different (P=.340) for both groups, and most failures were at the bracket-adhesive interface. CONCLUSION: The present findings indicate that increasing the SEP application from 3 to 5 seconds to 15 seconds does not result in a significant increase in SBS.     

甘氨酸对新型胶原基人工骨材料细胞毒性影响的体外研究

目的 研究甘氨酸对新型胶原基人工骨材料的细胞毒性的影响.方法 提取兔骨髓基质细胞,传至第三代.在含或不含10g/L甘氨酸的培养液中与自行研发的胶原基人工骨材料共培养,定期计数存活细胞,另将胶原基人工骨材料经甘氨酸处理或直接与第三代兔骨髓基质细胞复合,用扫描电镜观察细胞黏附情况.结果 人工骨材料组加入甘氨酸后的细胞贴壁数明显高于无甘氨酸组.扫描电镜观察甘氨酸处理后的人工骨表面有细胞黏附,未处理组则无细胞黏附.结论 甘氨酸可有效降低新型胶原基人工骨材料的细胞毒性.     

Effects of a self-etching primer and 37% phosphoric Acid etching on enamel: a scanning electron microscopic study

Objective: The purpose of this study was to compare the etching effects of a self-etching primer with 37% phosphoric acid on enamel by using a scanning electron microscope. Bond strength and the site of bond failure were also determined for brackets bonded using SEP and 37% phosphoric acid. Materials and methods: A total of 60 maxillary premolar teeth were used for this study and they were divided into four groups. First two groups were used for studying the different types of etch patterns obtained and the next two groups were used to test the bond strength with the help of Universal testing machine. After debonding, the amount of residual adhesive was assessed according to adhesive remnant index using a stereomicroscope. Results: The majority of etch patterns obtained in the 37% phosphoric acid group were type II, whereas in the SEP group, type IV pattern was more common. There was no statistically significant difference between mean bond strengths obtained with the SEP group and the phosphoric acid group. Use of SEP results in less amount of residual adhesive on tooth surface after debonding. Conclusion: SEP produces more conservative etch pattern compared to 37% phosphoric acid. Use of SEP for bonding provides similar and clinically acceptable bond strength compared to use of 37% phosphoric acid etching technique and requires less clean-up procedures hence, reduces enamel loss. Clinical significance: Use of 37% phosphoric acid for orthodontic bonding yields high bond strength but, causes enamel loss during both etching and debonding. SEPs not only provide adequate bond strength with a more conservative etch pattern but also enable easy debonding, thereby reducing the enamel damage. Keywords: Etch pattern, Enamel, SEM, Self-etching primer. How to cite this article: Nanjannawar LG, Nanjannawar GS. Effects of A Self-Etching Primer and 37% Phosphoric Acid Etching on Enamel: A Scanning Electron Microscopic Study. J Contemp Dent Pract 2012;13(3):280-284. Source of support: Nil Conflict of interest: None declared.     

Pulp ECM-derived macroporous scaffolds for stimulation of dental-pulp regeneration process

ObjectiveRecent studies suggest xenogeneic extracellular matrices as potential regenerative tools in dental pulp regeneration. This study aimed to fabricate and characterize a novel three-dimensional macroporous pulp-derived scaffold that enables the attachment, penetration, proliferation and differentiation of mesenchymal stem cells.MethodBovine pulp was decellularized and characterized with histological and DNA content methods. This scaffold was prepared using finely milled lyophilized decellularized pulp extracellular matrix (ECM) digested with pepsin. Three different concentrations of ECM (1.50, 2.25 and 3.00 mg/ml) were freeze-dried and were tested with/without chemical crosslinking. The specimens were subjected to physicochemical characterization, cell viability and quantitative real time polymerase chain reaction assessments with human bone marrow mesenchymal stem cells (hBMMSCs). All scaffolds were subcutaneously implanted in rats for two weeks and histological and immunostaining analyses were performed.ResultsHistological and DNA analysis confirmed complete decellularization. All samples demonstrated more than 97% porosity and 1.50 mg/ml scaffold demonstrated highest water absorption. The highest cell viability and proliferation of hBMMSCs was observed on the 3.00 mg/ml crosslinked scaffolds. The gene expression analysis showed a significant increase of dmp-1 and collagen-I on 3.00 mg/ml crosslinked scaffolds compared to the other scaffolds. Histological examination of subcutaneous implanted scaffolds revealed low immunological response, and enhanced angiogenesis in cross-linked samples compared to non-crosslinked samples.SignificanceThe three-dimensional macroporous pulp-derived injectable scaffold developed and characterized in this study displayed potential for regenerative therapy. While the scaffold biodegradability was decreased by crosslinking, the biocompatibility of post-crosslinked scaffold was significantly improved.