Antibacterial activity and ion release of bonding agent containing amorphous calcium phosphate nanoparticles

ObjectiveRecurrent caries at the margins is a primary reason for restoration failure. The objectives of this study were to develop bonding agent with the double benefits of antibacterial and remineralizing capabilities, to investigate the effects of NACP filler level and solution pH on Ca and P ion release from adhesive, and to examine the antibacterial and dentin bond properties.MethodsNanoparticles of amorphous calcium phosphate (NACP) and a quaternary ammonium monomer (dimethylaminododecyl methacrylate, DMADDM) were synthesized. Scotchbond Multi-Purpose (SBMP) primer and adhesive served as control. DMADDM was incorporated into primer and adhesive at 5% by mass. NACP was incorporated into adhesive at filler mass fractions of 10%, 20%, 30% and 40%. A dental plaque microcosm biofilm model was used to test the antibacterial bonding agents. Calcium (Ca) and phosphate (P) ion releases from the cured adhesive samples were measured vs. filler level and solution pH of 7, 5.5 and 4.ResultsAdding 5% DMADDM and 10–40% NACP into bonding agent, and water-aging for 28 days, did not affect dentin bond strength, compared to SBMP control at 1 day (p > 0.1). Adding DMADDM into bonding agent substantially decreased the biofilm metabolic activity and lactic acid production. Total microorganisms, total streptococci, and mutans streptococci were greatly reduced for bonding agents containing DMADDM. Increasing NACP filler level from 10% to 40% in adhesive increased the Ca and P ion release by an order of magnitude. Decreasing solution pH from 7 to 4 increased the ion release from adhesive by 6–10 folds.SignificanceBonding agents containing antibacterial DMADDM and remineralizer NACP were formulated to have Ca and P ion release, which increased with NACP filler level from 10% to 40% in adhesive. NACP adhesive was “smart” and dramatically increased the ion release at cariogenic pH 4, when these ions would be most-needed to inhibit caries. Therefore, bonding agent containing DMADDM and NACP may be promising to inhibit biofilms and remineralize tooth lesions thereby increasing the restoration longevity.     

Dentinogenic Responses after Direct Pulp Capping of Miniature Swine Teeth with Biodentine

Introduction

The aim of this study was to evaluate pulpal responses after experimental direct pulp capping of mechanically exposed teeth with a new calcium silicate–based dentin replacement material.

Methods

Thirty-four anterior and posterior teeth of 3 miniature swine were used. Class V or I cavities were prepared on the buccal or occlusal surfaces, respectively. Pulpal exposures were further performed using a round carbide bur 0.8 mm in diameter. Exposures were treated with white MTA Angelus (Angelus, Londrina, PR, Brazil) or Biodentine (Septodont, Saint Maur des Fosses, France), and the cavities were further restored with Biodentine. The pulpal tissue responses were histologically assessed at postoperative periods of 3 and 8 weeks. Data were statistically analyzed using the Kruskal Wallis and the Mann-Whitney U tests.

Results

Inflammatory infiltration or pulp tissue necrosis was not found in any of the specimens. All teeth showed mineralized matrix formation in the form of a complete hard tissue bridge composed of osteodentin or osteodentin followed by a discontinuous or continuous reparative dentin zone. A significantly higher thickness of the hard tissue bridge was found in the group of teeth treated with Biodentine at both 3 and 8 weeks. A number of teeth, which were under root development at the onset of the experimental procedures, exhibited ectopic pulp calcification.

Conclusions

The application of both calcium silicate–based materials in direct contact with the mechanically exposed pulp of healthy miniature swine teeth led to pulp repair with complete hard tissue bridge formation. The thickness of hard tissue bridges was significantly higher after pulp capping with Biodentine.     

Inhibition of enamel demineralization by buffering effect of S‐PRG filler‐containing dental sealant

The buffering capacity and inhibitory effects on enamel demineralization of two commercially available dental sealants were evaluated in this study. The effects of filler particles were also examined. Disks of enamel and cured sealant materials of BeautiSealant (silica or S‐PRG filler) or Teethmate F‐1 were incubated in lactic acid solutions (pH 4.0) for 1–6 d. The pH changes and amounts of ions released in the solutions were assessed, and enamel surfaces were observed using a scanning electron microscope. The pH of the solution with BeautiSealant (S‐PRG filler) was neutralized from pH 4.0 to pH 6.1 (after incubation for 1 d) and from pH 4.0 to pH 6.7 (after incubation for 6 d). In addition, no release of calcium ions was detected and the enamel surface was morphologically intact in scanning electron microscopy images. However, the pH of the solution with Teethmate F‐1 remained below pH 4.0 during incubation from days 1 to 6. Calcium release was increased in solutions up to and after 6 d of incubation. Scanning electron microscopy images showed that the structures of hydroxyapatite rods were exposed at the specimen surfaces as a result of demineralization. Ions released from S‐PRG filler‐containing dental sealant rapidly buffered the lactic acid solution and inhibited enamel demineralization.     

钙离子拮抗剂致药物性牙龈增生的危险因素分析

目的：探讨高血压患者服用钙离子拮抗剂后出现牙龈增生的患病率。方法：对我院查体中心和心血管内科门诊服用钙离子拮抗剂抗高血压类药物的262和未服用钙离子拮抗剂的197例患者进行横断面调查。方法包括问卷调查和口腔牙周检查,其中牙龈增生的判定以牙龈增生指数（HI ）为诊断标准。对调查结果进行统计学分析。结果：服用钙离子拮抗剂类药物患者的牙龈增生患病率为20．23％,显著高于对照组的2．54％（χ2＝32．276,P＜0．05）。随年龄增大,药物性牙龈增生的患病率降低（r＝－0．155,P＜0．05）;单一用药者较联合用药者患病率高;服药时间越长患病率降低;随服药剂量的增加,患病率明显增长;口腔卫生状况差者可加重牙龈增生程度。结论：药物性牙龈增生是多方面作用的结果,其主要影响因素为患者年龄、服药方式、剂量、时间和牙周局部因素。     

酪蛋白磷酸多肽-无定形磷酸钙复合物对窝沟封闭剂耐久性的影响

目的：评价酪蛋白磷酸多肽-无定形磷酸钙复合物（CPP-ACP）对窝沟封闭剂粘结系统耐久性的影响.方法：选取第三磨牙28颗,用低速涡轮钻沿颊舌向劈开,随机分为2实验组、2对照组.实验组经CPP-ACP处理后再分别用传统酸蚀系统和自酸蚀粘结系统进行窝沟封闭.对照组清水处理再分别进行两种方法的封闭.分别测定37℃水浴保存24 h和30 d的剪切黏结强度（SBS）,并用扫面电镜（SEM）观察断裂面形态.结果：实验组剪切粘结强度明显大于对照组（P＞1）,SEM结果显示全酸蚀实验组多为内聚破坏.结论：使用CPP-ACP可以提高窝沟封闭剂的粘结耐久性.     

被动吸烟对鼠牙槽骨钙、磷含量及碱性磷酸酶活性的影响

目的 分析被动吸烟鼠牙槽骨钙、磷含量和碱性磷酸酶（AKP）的活性。方法 40只6周龄健康雄性Wistar鼠被随机等量分为实验组和对照组,每组再被随机等量分为15、30、45和60 d 4个亚组,烟熏法建立被动吸烟的大鼠模型,浓酸消化法提取牙槽骨内钙和磷,光谱分析法和改良Reddi法分别测定钙、磷含量和AKP的活性,行析因设计的方差分析。结果 与各对照组牙槽骨相比,被动吸烟鼠的钙、磷含量在15 d组略有升高,30 d组略有下降,差异无统计学意义（P〉0.05）,45、60 d组显著下降（P〈0.01）;AKP活性在15、30 d组略升高,45、60 d组略下降,差异无统计学意义（P〉0.05）。结论 本实验周期内,鼠牙槽骨钙、磷含量和AKP活性在被动吸烟初期略有升高,随被动吸烟时间的延长,钙、磷含量呈时间依赖性减少,AKP活性也呈时间依赖性减少的趋势。     

Method to examine how geometry affects the release and retention of alpine touring boot-binding systems

ObjectivesDevelop a method to examine the effects of component geometry and force-deflection on the release process of Tech/Pin alpine touring (AT) ski boots and bindings.Design and methodsFor seven AT boots, we measured the critical geometric dimensions of the metal inserts at the toe region of the boots. Binding geometry (including the pins and rocker arms) and the force-angular deflection curves of typical AT bindings were measured. A kinematic model was derived to predict the contact force between the metal inserts of the AT boots and the pins of the AT bindings, dependent on angular displacement of the binding rocker arms. By combining the kinematic model, the force-angular deflection curves, and moment equilibrium, we determined the force and binding rotation angle needed to release the AT boot in a direction normal to the ski.ResultsThe metal AT boot insert geometry and AT binding pin geometry and dimensions can affect significantly the contact states and kinematics of release. Two load-deflection curves of similar peak loads can result in significantly different maximal forces and angles to release the binding, even when the geometry and dimensions of the binding pins and boot inserts remain unchanged.ConclusionsThe geometry and dimensions of the binding (pins and rocker arm) and the boot inserts define the kinematics of the binding release. The model can be used to test the effects of varying parameters on the release and retention characteristics of Tech/Pin boot-binding systems to optimize the release and retention characteristics.     

低分子量肝素钙在老年糖尿病肾病中的应用效果评价

目的 探讨低分子量肝素钙在老年糖尿病肾病患者治疗中的有效性和安全性.方法 选择本院2013年1月至2014年12月收治的80例老年糖尿病肾病患者作为研究对象,根据随机数字表法分为两组,对照组40例给予依那普利治疗,观察组40例在对照组治疗的基础上加用低分子量肝素钙治疗,治疗8周后比较两组患者的临床疗效、肾功能指标变化及不良反应发生情况.结果 观察组总有效率为90.00％,显著高于对照组的75.00％,差异有统计学意义(Z =2.062,P＜0.05);治疗后,观察组Scr、24hUMA、ATⅡ均低于对照组,CCr高于对照组,差异有统计学意义(P＜0.05).结论 低分子量肝素钙提高了老年糖尿病肾病患者临床治疗效果,显著改善了患者肾功能,且无严重不良反应发生,值得临床重视.     

Release of pig leukocytes and reduced human NK cell recruitment during ex vivo perfusion of HLA‐E/human CD46 double‐transgenic pig limbs with human blood

Background

In pig‐to‐human xenotransplantation, interactions between human natural killer (NK) cells and porcine endothelial cells (pEC) are characterized by recruitment and cytotoxicity. Protection from xenogeneic NK cytotoxicity can be achieved in vitro by the expression of the non‐classical human leukocyte antigen‐E (HLA‐E) on pEC. Thus, the aim of this study was to analyze NK cell responses to vascularized xenografts using an ex vivo perfusion system of pig limbs with human blood.

Methods

Six pig forelimbs per group, respectively, stemming from either wild‐type (wt) or HLA‐E/hCD46 double‐transgenic (tg) animals, were perfused ex vivo with heparinized human blood for 12 hours. Blood samples were collected at defined time intervals, cell numbers counted, and peripheral blood mononuclear cells analyzed for phenotype by flow cytometry. Muscle biopsies were analyzed for NK cell infiltration. In vitro NK cytotoxicity assays were performed using pEC derived from wt and tg animals as target cells.

Results

Ex vivo, a strong reduction in circulating human CD45 leukocytes was observed after 60 minutes of xenoperfusion in both wt and tg limb groups. NK cell numbers dropped significantly. Within the first 10 minutes, the decrease in NK cells was more significant in the wt limb perfusions as compared to tg limbs. Immunohistology of biopsies taken after 12 hours showed less NK cell tissue infiltration in the tg limbs. In vitro, NK cytotoxicity against hCD46 single tg pEC and wt pEC was similar, while lysis of double tg HLA‐E/hCD46 pEC was significantly reduced. Finally, circulating cells of pig origin were observed during the ex vivo xenoperfusions. These cells expressed phenotypes mainly of monocytes, B and T lymphocytes, NK cells, as well as some activated endothelial cells.

Conclusions

Ex vivo perfusion of pig forelimbs using whole human blood represents a powerful tool to study humoral and early cell‐mediated rejection mechanisms of vascularized pig‐to‐human xenotransplantation, although there are several limitations of the model. Here, we show that (i) transgenic expression of HLA‐E/hCD46 in pig limbs provides partial protection from human NK cell‐mediated xeno responses and (ii) the emergence of a pig cell population during xenoperfusions with implications for the immunogenicity of xenografts.