后牙复合树脂充填的抗折裂性能

本实验选择上颌第一双尖牙，按要求制备成ＭＯＤ洞型，单独充填光敏复合树脂、分别衬垫玻璃离子粘固剂（ＧＩＣ）与光敏固化氢氧钙后，充填光敏复合树脂，充填ＧＫ高铜银汞合金和不充填窝洞，测试各组的牙体抗折裂性能并比较。结果发现，衬垫ＧＩＣ组的牙体抗折力最高，其次为单独充填光敏复合树脂组，未充填组牙体抗折力最低，差别均极显著（Ｐ〈０．０１）。提示我们，临床应用复合树脂充填能增强牙体的抗折裂性能，采用ＧＩＣ衬垫     

牙修复后折裂的原因及预防

本文从窝洞制备，牙髓病治疗及修复材料等各个环节对牙齿折裂的影响进行分析，并提出了相应的预防措施，以延长修复后牙体的寿命。     

牙修复后折裂的原因及预防

本文从窝洞制备、牙髓病治疗及修复材料等各个环节对牙齿折裂的影响进行分析,并提出了相应的预防措施,以延长修复后牙体的寿命。     

离体磨牙不同洞型干髓术后抗折力实验研究

目的 对离体磨牙制四种型模拟干髓术进行抗折裂负荷测试。方法 取离体完整后磨牙分成５组，每组３２颗，Ａ组为对照组（完整牙）Ｂ组，Ｃ组，Ｄ组和Ｅ组分别制备成Ｈｅ面洞，邻Ｈｅ洞，颊面洞和邻颊（舌）洞，模拟干髓术后进行银汞充填术，然后在１０吨液压式无万能试验机进行裂负荷测试。结果 其抗折力分别为完整牙４３２４．１７Ｎ（４４１．２６ｋｇｆ）Ｈｅ面洞型２０２３．４１Ｎ（２０６．４ｋｇｆ）邻Ｈｅ洞型１８７３．３     

桩和根管重塑材料对薄壁牙体抗折性能的影响

目的:探讨如何选择合适直径的桩和根管重塑材料,使薄壁根管获得更好的抗折性能。方法:选择90颗完整的上颌中切牙,完成根管治疗后,截冠分为9组。其中,4组进行常规桩道预备后行1.3 mm、1.6 mm镍铬合金铸造桩(A1.3和A1.6)和玻璃纤维桩(B1.3和B1.6)黏结后全冠修复,其余5组桩道扩大至根管壁为1 mm后行铸造桩核(C)和玻璃纤维桩修复,其中1.3、1.6 mm纤维桩用Rely X Unicem(D1.3和D1.6)和ParaCore(E1.3和E1.6)进行根管重塑和黏结,再用复合树脂堆核型后全冠修复,比较各组的抗折力和折裂模式。采用SPSS16.0软件包对数据进行统计学分析。结果:常规根管中,A1.3组获得最大的抗折力(610.2±45.6)N,A1.3、A1.6和B1.3、B1.6之间无显著差异(P>0.05)。薄壁根管中,C组获得最大的抗折力(584.5±121.2)N,而纤维桩经ParaCore重塑根管后可以增加牙体的抗折力[E1.3为(420.6±95.7) N,E1.6为(517.9±67.2) N],分别较D1.3和D1.6有显著差异(P<0.05),而与B1.3、B1.6无显著差异(P>0.05)。纤维桩修复的折裂模式中大部分可以重新修复,而金属桩大部分为破坏性。结论:纤维桩修复后,折裂的牙体大部分可以再次修复,1.3 mm和1.6 mm直径的桩对于牙体的抗折性无显著影响,ParaCore重塑根管可有效增强牙体的抗折性能。     

银汞桩核抗折裂强度的体外研究

目的：比较不同深度的银汞桩核修复后牙体组织的抗折裂强度和折裂模式。方法：选取40个完整拔除的下颌单根管前磨牙，常规根管治疗后，按颊舌径的大小分为4组，每组10个。Ⅰ、Ⅱ、Ⅲ组制作不同深度的银汞桩核，Ⅳ组为对照组。试件的底座固定在电子式万能测试仪上加载，记录试件折裂时测试机上的读数以及试件折裂的模式。结果：Ⅰ、Ⅱ、Ⅲ组之间无显著性差异（P〉0．05），Ⅰ、Ⅱ、Ⅲ组与Ⅳ组之间有显著性差异（P〈0．01）。结论：银汞桩核抗折裂强度与深度无关，其强度能满足人日常咀嚼食物所需的[牙合]力。     

离体前磨牙邻面颈部龋一种新洞型抗折裂性能的实验研究

目的对邻面颈部龋一种新洞型及传统洞型进行抗折裂负荷测试,并对新洞型与传统洞型的抗折裂性能进行比较。方法收集200颗完整的离体前磨牙,随机分成A、B、C、D 4组,A组为对照组,B组制备成牙合面洞,C组制备成邻颊(舌)面洞+牙合面洞(即新洞型,简称“双洞型”),D组制备成邻牙合面洞,模拟根管治疗后行银汞充填,用微机控制电子万能测试机对离体牙进行抗折裂负荷测试,测试各组实验牙折裂时的压力强度值。结果牙体折裂时的压力强度均值分别是:A组4 523.17 N,B组2 357.41 N,C组2 343.25 N,D组1 784.22 N。经统计学分析:C组抗折力明显高于D组,C组与B组抗折力接近,B、C、D抗折力明显低于A组。结论新设计的“双洞型”抗折力优于传统的邻牙合面洞型。     

垂直加载时基底材料及充填体对牙齿抗折力的影响

目的 研究窝洞形态、基底材料和充填体如何共同影响牙齿的抗折力。方法 采用三因素不同水平的析因实验设计,用上颌离体第一前磨牙在万能测试机上垂直加载直至折裂。记录最大折裂力和折裂方式,用三因素方差分析分析结果。结果 窝洞的形态和充填体种类对牙齿的抗折裂力影响明显,不同材料牙折的方式不同。结论 充填体的种类和窝洞形态是影响抗折力的主要因素,洞型和充填体之间存在交互作用。     

玻璃纤维桩修复不同缺损程度前牙抗折裂性能的比较

将离体上前牙进行根管治疗后分为4 组,使用玻璃纤维桩修复后测试抗折裂强度.结果显示:牙本质肩领为2 mm组抗折裂强度较高.     

三种方法预备下颌第二磨牙C形根管成形效果的比较

目的 评价3种常用根管预备方法对C形根管的成形效果,为临床治疗提供参考.方法 对临床拔除的具有C形根管的下颌第二恒磨牙60颗,应用改良Bramante技术,于距根尖2mm、5 mm和8mm处将牙根横断.选择手用不锈钢K锉逐步后退技术(Step-Back组)、逐步深入技术(Step-Down组)和机用旋转镍钛锉ProTaperTM系列冠向下预备技术(Crown-Down组)预备不同类型的C形根管,比较预备前后根管横截面形态的数码图像,对3种不同方法的成形效果进行评价.结果 3种方法预备离体下颌第二磨牙C形根管后均有遗漏.不锈钢K锉逐步后退技术和不锈钢K锉逐步深入技术分别在根冠部[遗漏面积百分比分别为(0.177±0.071)%、(0.068±0.074)%]和根尖部[遗漏面积百分比分别为(0.236±0.167)%、(0.295±0.171)%]遗漏较少(P＜0.05).CⅠ、CⅡ型遗漏出现在近远中多于颊舌侧,将其分为独立的2～3个根管预备可减少遗漏.不同方法预备根尖区的遗漏均显著高于根管中上部(P＜0.05).结论 早期开敞根管上段,将C形根管分为2～3个独立的根管进行预备,可以增进根管预备的成形效果.     

应用新型体外实验系统对牙科修复材料抗磨损性的研究

目的：评价牙科复合树脂材料的抗磨损性。方法：应用程控多功能口腔模拟机和三维图像激光测试仪对４种牙科复合树脂进行抗磨损性的实验研究。结果：材料磨损坑体积大小的顺序为：牙釉质〈Ｔａｒｇｉｓ Ｄｅｎｔｉｎ〈Ｄｅｎｔａｃｏｌｏｒ〈Ａｒｔｇｌａｓｓ〈Ｖｉｔａ Ｚｅｔａ。磨损坑最深点大小的顺序为：牙釉质〈Ｔａｒｇｉｓ Ｄｅｎｔｉｎ〈Ａｒｔｇｌａｓｓ〈Ｄｅｎｔａｃｏｌｏｒ〈Ｖｉｔａ Ｚｅｔａ。结论：Ｔａｒｇｉｓ     

Establishment of a New Marginal Plaque Index With High Sensitivity for Changes in Oral Hygiene

Background: Although several plaque indices exist, they rarely assess in detail the plaque adjacent to the gingival margin, an area most important for periodontal health. This study aims to develop a new marginal plaque index (MPI) and to assess its validity and treatment sensitivity compared to the internationally accepted Turesky modification of the Quigley and Hein Index (TQHI). Methods: Data from two studies with n = 64 and n = 67 participants, respectively, are reported here. Convergence of MPI with TQHI and concurrent and predictive validity with papillary bleeding index were assessed, as was treatment sensitivity to a treatment of proximal hygiene (study 1) or toothbrushing (study 2), respectively. Results: Convergent validity with TQHI is very good. Concurrent and predictive validity parameters of the MPI are similar to the TQHI. The treatment sensitivity of MPI exceeds TQHI by far. This results in a reduction by >70% of the sample size needed to discover significant treatment effects. As expected, the largest treatment sensitivity was observed for proximal MPI measures in study 1, whereas study 2 showed largest effects for cervical measures. Conclusions: MPI appears to be a valid plaque‐scoring system that assesses plaque at the gingival margin. It responds with high sensitivity to treatments aimed at plaque reduction at the gingival margin. Its treatment sensitivity and capacity to differentiate between proximal and cervical plaque make it a promising tool for periodontal research.     

The Effectiveness of a Calcium Sodium Phosphosilicate Desensitizer in Reducing Cervical Dentin Hypersensitivity

BackgroundNovaMin (NovaMin Technology, Alachua, Fla.) was introduced into the dental market as a desensitizer in December 2004. However, to the authors' knowledge, no researchers yet have evaluated the effectiveness of 100 percent NovaMin powder with NovaMin-containing toothpaste in reducing dentin hypersensitivity compared with the effectiveness of NovaMin-containing toothpaste only and a desensitizing toothpaste containing potassium nitrate as a control.MethodsThe authors divided 60 participants randomly into three groups: NovaMin powder with NovaMin-containing toothpaste (group 1), a placebo powder with NovaMin-containing toothpaste (group 2) and a placebo powder with the control toothpaste (group 3). The authors used tactile and cold stimuli and a visual analog scale to evaluate participants' pain at baseline, immediately after powder application and at one week, two weeks and four weeks after powder application. They analyzed data by using Friedman and Wilcoxon signed-rank tests for within-group comparison. They used Kruskal-Wallis and Mann-Whitney U tests for between-group comparison. They considered P < .05 to be statistically significant.ResultsGroups 1 and 2 showed significant hypersensitivity reduction over baseline at all time points. Group 3 showed significant hypersensitivity reduction at one week onward. Group 1 showed significant improvement compared with groups 2 and 3, except for response to tactile stimulus at four weeks with group 2. Between groups 2 and 3, there were significant differences at two and four weeks.Conclusions and Clinical ImplicationsThe use of NovaMin powder and NovaMin-containing toothpaste for hypersensitivity reduction is more effective than the use of a desensitizing toothpaste containing potassium nitrate and fluoride.     

新型纳米根管充填材料体外基因毒性的初步研究

目的　采用体外微核法评价新型纳米根管充填材料nHA-PA66的基因毒性。方法　以V79细胞作为实验细胞,采用新型纳米根管充填材料nHA-PA66粉剂及混合物的浸提液作为实验组,丝裂霉素C为阳性对照组,用 MTT法检测各组的细胞毒性,以V79细胞中所形成的微核数作为标准评价材料的基因毒性。结果　实验组的MTT 值在各个时间段与阴性对照组无显著性差异(P>0·05);所形成的微核数(粉剂组:6·1±1·1/1 000;混合物组:5·7± 0·6/1 000)与阴性对照组(5·3±0·8/1 000)无显著性差异(P>0·05),而与阳性对照组(123·9±8/1 000)有显著性差异 (P<0·05)。结论　本实验显示新型纳米根管充填材料nHA-PA66无细胞毒性及基因毒性,生物相容性好。