Effect of the infrastructure material on the failure behavior of prosthetic crowns

Objectives

To evaluate the effect of infrastructure (IS) material on the fracture behavior of prosthetic crowns.

Methods

Restorations were fabricated using a metal die simulating a prepared tooth. Four groups were evaluated: YZ-C, Y-TZP (In-Ceram YZ, Vita) IS produced by CAD-CAM; IZ-C, In-Ceram Zirconia (Vita) IS produced by CAD-CAM; IZ-S, In-Ceram Zirconia (Vita) IS produced by slip-cast; MC, metal IS (control). The IS were veneered with porcelain and resin cemented to fiber-reinforced composite dies. Specimens were loaded in compression to failure using a universal testing machine. The 30° angle load was applied by a spherical piston, in 37 °C distilled water. Fractography was performed using stereomicroscope and SEM. Data were statistically analyzed with Anova and Student–Newman–Keuls tests (α = 0.05).

Results

Significant differences were found between groups (p = 0.022). MC showed the highest mean failure load, statistically similar to YZ-C. There was no statistical difference between YZ-C, IZ-C and IZ-S. MC and YZ-C showed no catastrophic failure. IZ-C and IZ-S showed chipping and catastrophic failures. The fracture behavior is similar to reported clinical failures.

Significance

Considering the ceramic systems evaluated, YZ-C and MC crowns present greater fracture load and a more favorable failure mode than In-Ceram Zirconia crowns, regardless of the fabrication type (CAD-CAM or slip-cast).     

Ceramage聚合瓷和IPS e.max Press材料磨损实验

目的 分析Ceramage和IPS e.max Press材料的耐磨性差异,为临床选择合适的非金属修复体材料提供参考.方法 收集近3个月内拔除的完整上颌第一磨牙10颗、无磨损上颌第三磨牙20颗.使用特定车针修整上颌第三磨牙腭尖形态,使成为标准化釉质加载尖,随机分为Ceramage釉质对照组和IPS e.max Press釉质对照组.将离体第一磨牙标本沿牙体颊舌侧中点连线平行牙长轴方向纵切为近中、远中两部分,随机分为Ceramage嵌体组和IPS e.max Press嵌体组;将样本近远中邻面片切成平面后进行Ⅰ类洞嵌体预备,以相应材料制作嵌体,Varolink N粘结.用自制咀嚼磨损测试机于20 N加载力下循环20万次,采用Kavo PREPassistant扫描系统测量样本的磨损深度.分析两组嵌体材料的磨损量、釉质对照组磨损量差异.结果 嵌体与釉质的磨损量分别为:Ceramage嵌体组材料磨损量(298.30±40.02)μm、釉质对照组(206.60±49.17)μm;IPS e.max Press嵌体组材料磨损量(212.90±61.21)μm、釉质对照组(217.00±25.10)μm.两组嵌体材料的磨损量结果表明,IPS e.max Press全瓷材料的磨损量小于Ceramage瓷聚体(P<0.05).Ceramage嵌体磨损量大于Ceramage釉质对照组磨损量(P<0.05),而IPS e.max Press嵌体组与釉质对照组之间磨损量差异无统计学意义(P>0.05).结论 Ceramage瓷聚体材料耐磨性较IPS e.max Press全瓷材料差.Ceramage瓷聚体磨损量大于天然牙釉质,耐磨性较牙釉质差;IPS e.max Press耐磨性好.     

氯化镧对脱矿釉质再矿化的影响

为了了解镧对脱矿釉质矿化的影响，以基础矿化液及含１０ｐｐｍｌａ＾３＋或氟的矿化液分别处理脱矿后人牙釉质，再作实验开窗区剖面表及里的显微硬度测定，结果显示各试验组表层硬度明显低于内层硬度，但１００μｍ以内各点之硬度值比较差异均无显著性，以各实验组相比较，表层硬度值之间差异有显著性，其他层次相应点之间硬度值无无显著性。     

含氟牙线牙周临床效果初探

对５８名志愿者随机分为Ａ、Ｂ两组，每人全口牙分为用牙线侧（Ａ１或Ｂ１）不用牙线侧（Ａ２或Ｂ２）。Ａ１用含氟牙线，Ｂ１用不含氟牙线。结果显示：用牙线１周后，各组受试者菌斑指数（ＰＬＩ）、牙龈出血指数（ＢＩ）均数都明显降低（Ｐ〈０．０１）。各组间差异无显著性（Ｐ〉０．０５）。但龈下菌斑中螺旋体的比例（Ｓ％）仅用含氟牙线的Ａ１降低显著（Ｐ〈０．００１）。停用牙线１周后，各组ＰＬ１、ＢＩ均数都有回升，Ａ１     

Physicochemical and mechanical characterization of a fiber-reinforced composite used as frameworks of implant-supported prostheses

ObjectivesTo characterize the physicochemical and mechanical properties of a milled fiber-reinforced composite (FRC) for implant-supported fixed dental prostheses (FDPs).MethodsFor FRC characterization, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction, Fourier-transformed infrared spectrometry, simultaneous thermogravimetric analysis and differential scanning calorimetry were performed. For fatigue testing, 3-unit FRC frameworks were fabricated with conventional (9 mm² connector area) and modified designs (12 mm² connector area and 2.5 mm-height lingual extension). A hybrid resin composite was veneered onto the frameworks. FDPs were subjected to step-stress accelerated-life fatigue testing until fracture or suspension. Use level probability Weibull curves at 300 N were plotted and the reliability for 100,000 cycles at 300, 600 and 800 N was calculated. Fractographic analysis was performed by stereomicroscope and SEM.ResultsThe FRC consisted of an epoxy resin (∼25%) matrix reinforced with inorganic particles and glass fibers (∼75%). Multi-layer continuous regular-geometry fibers were densely arranged in a parallel and bidirectional fashion in the resin matrix. Fatigue analysis demonstrated high probability of survival (99%) for FDPs at 300 N, irrespective of framework design. Conventional FDPs showed a progressive decrease in the reliability at 600 (84%) and 800 N (19%), whereas modified FDPs reliability significantly reduced only at 800 N (75%). The chief failure modes for FRC FDPs were cohesive fracture of the veneering composite on lower loads and adhesive fracture of the veneering composite at higher loads.SignificanceMilled epoxy resin matrix reinforced with glass fibers composite resulted in high probability of survival in the implant-supported prosthesis scenario.     

牙菌斑液对牙釉质矿物的饱和程度与龋活动性的关系

为了解菌斑液对牙齿矿物饱和度随糖漱口的变化，以及与龋活动性的关系，作者选择２２例年龄相同的大学生，按龋齿情况，将其分为３组。第１组无龋（无龋组），第２组ＤＭＦＳ大于１０但无活动性龋（普通龋组），第３组ＤＭＦＳ大于１０且有活动性龋（活动性龋组），测定各受试者在静止时、用蔗糖液漱口后３ｍｉｎ和７ｍｉｎ时的菌斑液中有机酸、ｐＨ值、钙离子活度（有效离子浓度）和无机成分的含量，并计算对于釉质矿物的饱和度。结果表明，糖漱口之后菌斑液乳酸浓度升高、ｐＨ值降低、总钙和离子钙浓度增加。活动性龋组的菌斑液在糖漱口后ｐＨ值和饱和度降低的幅度明显大于无龋组和普通龋组。结论：牙菌斑液对牙齿矿物的饱和度是指示个体接受致龋食物后牙齿脱矿倾向的敏感指标。     

天津钢管公司职工龋齿状况调查分析

目的了解并分析天津钢管公司职工口腔龋齿发生状况,为口腔预防保健工作提供信息支持。方法参照WHO 1997年制定的口腔健康调查基本方法和第三次全国口腔流行病学调查标准和方法,对8348名职工进行口腔龋齿检查。结果 8348名受检者患龋率47.22%,龋均1.39。结论天津钢管公司职工口腔龋齿发生状况好于第三次全国口腔流行病学调查结果,但患龋率、龋均随年龄的增长逐渐增高,应加大对该人群口腔卫生保健知识的宣传并采取相应的预防措施。     

模板在种植义齿修复中的制作与应用

目的：探讨模板在种植体植入的位置和方向上的导向作用，以及计算影象诊断的变形率。方法：利用热压成型法和自凝塑胶涂布法等在IT1、Anthogyr和BLB种植系统种植体植入中应用。结果：种植体植入颌骨中的位置、方向和角度基本准确，修复效果满意。结论：模板对提高种植义齿修复的质量有重要意义。     

Dental specialty,career preferences and their influencing factors among final year dental students in Saudi Arabia

Objective

The purpose of this study was to investigate evolving trends in dental post graduate specialty preferences and career aspirations among final year dental students in Saudi Arabia.

A comparison of dental service use among commercially insured women in Minnesota before, during and after pregnancy

BACKGROUND: The authors examined and compared dental services used by women before, during and after pregnancy. METHODS: In their study, the authors combined medical and dental claims data for 3,462 pregnant women in Minnesota with commercial dental insurance who had been pregnant between Jan. 1, 2004, and Dec. 31, 2005. The authors used McNemar pairwise comparisons, with each subject serving as her own control and her use of various dental services before pregnancy as her own baseline, to evaluate and compare the dental services used during and after pregnancy. RESULTS: During pregnancy, subjects' use of several dental services-radiographs, restorative services, third-molar extractions and anesthesia-decreased significantly (P < .001) in comparison with their prepregnancy use. After pregnancy, subjects' use of checkups, radiographs and restorative services showed significant increases (P < .001). CONCLUSIONS: The significant decreases in use of these services during pregnancy and significant increases after pregnancy may suggest that these women and their dentists were using these services only conservatively during pregnancy or postponing their use altogether until after delivery. CLINICAL IMPLICATIONS: This study's findings may provide useful background information to medical and dental providers, health care plan administrators and policymakers as they consider recommendations regarding oral health care for women during pregnancy.     

溶剂处理对钛-瓷结合强度的影响

目的 考察丙酮,乙酸乙酯,９５％乙醇及１５氢氟酸对钛－瓷结合产生的影响。方法 采用剪切实验法。结果 纯钛经丙酮、乙酸乙脂,９５％乙醇及１％氢氟酸处理后再烤瓷,太－瓷剪切强度分别为５３．２９ＭＰａ,５２．５４Ｍｐａ,５０．６９ＭＰａ,及２１．１８ＭＰａ,而未经任何清洗处理的对照组剪切强度值为２６．７５ＭＰａ。Ｔｉ－７５合金烤瓷前经丙酮,乙酸乙酯,９５％乙醇及１％氢氟酸处理后其钛－瓷剪切强度分别为５７     

饰瓷对磨牙e.max双层全瓷冠断裂类型的影响

目的：通过抗折破坏实验研究饰瓷对磨牙e.max双层全瓷冠断裂强度和断裂类型的影响,为减少临床双层全瓷修复体崩瓷提供实验依据。方法：制作单层全瓷冠（IPS e.max Press）和双层全瓷冠（IPS e.max Press/Ce-ram）共40个（每组20个）,粘接于树脂代型后进行抗折破坏实验并记录断裂强度值;体视显微镜和扫描电子显微镜下观察断裂类型;能谱分析饰瓷-核瓷界面化学元素构成。结果：单层全瓷冠断裂强度值[（2665.4±759.2）N]与双层全瓷冠[（1431.1±404.3）N]间差异有统计学意义（P=0.000）。饰瓷内部及饰瓷-核瓷界面缺陷催生裂纹造成饰瓷崩裂是双层全瓷冠断裂的主要模式。结论：饰瓷对磨牙e.max双层全瓷冠断裂强度和断裂类型均有影响;饰瓷内部及饰瓷-核瓷界面缺陷是全瓷冠断裂的主要原因,提高饰瓷断裂强度及减少界面缺陷可减少因崩瓷造成的修复体失败。     

用Replace种植修复体修复上颌前牙缺失

目的：本文报告单独用Replace种植体、或联合邻牙支持和固位的、用粘固剂固定的金属陶瓷单冠修复上颌前牙缺失患者的基本情况、临床修复程序,评价了种植修复体的临床应用效果.方法：用Replace种植体支持的种植单冠为25例患者缺失的31颗上颌前牙进行了修复治疗.22位患者（26枚种植牙）按期复查,其中,10位患者在种植体植入的同期接受了自体组织移植或人工骨植入手术.根据对种植体周围软组织健康情况、附丽高度、外形和色泽的临床观察,结合医、患双方对种植修复体的美观效果、功能状况满意度评价来确定修复效果.结果：种植牙修复后咀嚼功能恢复良好,面容和语音功能有显著改观,种植体周围软组织健康.种植单冠和修复基台的接缝位于龈下,种植牙给人以从龈下长出来的视觉效果,美观.20例按期复查的患者和修复医生对修复体、及其临床应用效果都评价为满意.2例患者对3个种植牙评价为可接受.结论：用Replace种植体支持的、暂时性粘固剂固定的种植上颌前牙能够获得医、患双方都满意或可接受的临床应用效果.     

不同龋敏感人群唾液理化性质的比较

对不同龋敏感人群唾液的分泌率、pH值、缓冲能力、粘度进行了比较.发现无龋组唾液分泌率、缓冲能力显著高于高龋组(P<0.02),无龋组唾液的粘度显著低于高龋组(P<0.01),两组间唾液pH值无显著性差异(P>0.05).以上结果提示唾液理化性质可能是影响龋病发生的重要因素之一.     

一种实用的牙齿漂白技术

将国际公认的牙齿漂白药物过氧化脲加入无毒高分子成膜剂配成胶状液 ,涂于干燥牙面1— 2分钟形成附着于牙面的薄膜 ,可维持 1小时以上。此期间过氧化脲分解释放新生氧而将牙齿漂白。临床研究表明 :牙齿增白涂膜是一种安全、有效、实用的漂白牙齿方法。本产品已获中国专利 (专利号 :96 1186 0 5.4 ,PCT/ CN97/ 0 0 0 0 4 )     

Comparative study on the effect of ultrasonic instruments on the root surface in vivo

The present study was designed to investigate the effectiveness of different ultrasonic instruments on the root surface. Fourteen patients with 35 single root teeth designated for extraction were recruited to the present study. Teeth were assigned to four experimental groups: group 1, piezoelectric ultrasonic device; group 2, magnetostrictive ultrasonic device; group 3, hand instrumentation; and group 4, untreated teeth (control). After instrumentation, the teeth were extracted and the presence of residual deposits (roughness and root surfaces characteristics) were analyzed. The results showed that residual deposits were similar in all tested groups: piezoelectric, 8.7%; magnetostrictive, 9.7%; hand instrumentation, 11.1% and control, 76.4%. There were statistically significant differences between control and all the experimental groups (p < 0.0001). With respect to roughness parameters evaluation, R_a and R_z of the roots treated with the different instruments showed a similar pattern (p > 0.05), but for R_t and R_y, a significant difference was observed (p < 0.05) among hand instrumentation and ultrasonic devices. SEM analysis revealed a similar root surface pattern for the ultrasonic devices, but curettes showed many instrumental scratches, deep gouges, and a relatively large amount of dentin was removed. Within the limits of the study, although the instruments produced similar results, root surfaces instrumentated with curettes were rougher and had more root surface tissue removed than with the ultrasonic device.