牙预备体表面经极固宁TM处理后对全冠固位力的影响

临床上行冠、桥修复时部分活髓牙会出现牙本质过敏症状,牙体制备后或粘固冠桥前应用极固宁TM处理牙本质表面,被认为是一种有效安全、作用持久、使用简单的处理方法。本研究旨在通过体外实验来评价极固宁TM处理牙预备体表面后对玻璃离子水门汀粘固的全冠固位力的影响。1材料与方     

全冠的牙体预备

全冠的牙体预备是修复体能否成功的前提。本文从He面聚合度，He龈／切龈距离与颊舌径的比值，轴面，He面，切缘的切削量，预备体外形和表面质地，冠的边缘方面探讨全冠牙体预备时应遵循的原则，有助于临床提高冠，桥的修复质量。     

全冠的牙体预备

全冠的牙体预备是修复体能否成功的前提。本文从(牙合)面聚合度,(牙合)龈/切龈距离与颊舌径的比值,轴面、(牙合)面、切缘的切削量,预备体外形和表面质地、冠的边缘方面探讨全冠牙体预备时应遵循的原则,有助于临床提高冠、桥的修复质量。     

全冠修复固位力的影响因素

全冠修复体通过粘固与牙体作为一个整体行使功能，因而如何保证其固位力是个关键问题。本文就全冠固位力的影响因素包括轴壁聚合度的大小、牙冠的高度、粘固剂的合理使用、表面的某些处理等作一综述。     

极固宁TM脱敏剂在牙体预备后的应用

目的 :总结极固宁脱敏剂治疗活髓牙牙体预备后牙本质敏感症的临床疗效。方法 :对 2 6例患者牙体制备后的冠核用极固宁脱敏剂涂布。结果 :经过极固宁脱敏剂治疗后 ,患者对温度的刺激痛明显减轻。结论 :对于制备后的活髓牙未用临时冠修复者 ,用极固宁脱敏剂治疗是护髓的一种好方法     

牙体高度与内聚角对全冠固位力的影响

目的通过测定不同高度和内聚角度牙体模型上全冠的固位力,以探讨低矮后牙全冠获得理想固位的合适牙体高度与锥度.方法制作高度分别为2mm、3mm、4mm,内聚角分别为2°、6°、10°的圆柱状金属牙体模型共9个.用滴蜡法在每个模型上制作6个金属全冠,全冠用玻璃离子进行粘固,应用EZ20拉力测试机进行冠固位力的测定.采用t检验比较不同高度和内聚角牙体的冠固位力之间的差异.结果4mm高度,内聚角为2°、6°、10°的各组平均冠固位力分别为149N、138N、105N;3mm高度,内聚角为2°、6°、10°的各组冠固位力分别为130N、124N、88N;2mm高度,内聚角为2°、6°、10°的各组冠固位力分别为124N、117N、82N.不同高度和内聚角各组牙体上冠固位力数据之间差异有统计学意义.结论全冠固位力与牙体高度成正比、与牙体内聚角度成反比,当冠高度低于3mm、内聚角大于6°时冠固位力出现明显下降.     

全冠修复固位力的影响因素

全冠修复体通过粘固与牙体作为一个整体行使功能,因而如何保证其固位力是个关键问题。本文就全冠固位力的影响因素包括轴壁聚合度的大小、牙冠的高度、粘固剂的合理使用、表面的某些处理等作一综述。     

影响全冠固位的因素

全冠是用各种牙科修复材料制作的覆盖全牙冠的修复体，其固位力的大小直接影响最终的修复效果。能否获得足够的固位，取决于牙体预备、粘固剂类型、粘结方法、技工制作、组织面处理等因素。本文就这些因素作一综述。     

极固宁TM对活髓基牙牙髓组织影响研究

目的 研究极固宁TM对金属烤瓷全冠活髓基牙牙体预备后1、2周牙髓组织形态学的影响。方法 选择2012年1月至2013年8月在福建医科大学附属口腔医院就诊患者15例,因正畸治疗需要而计划拔除40颗前磨牙（同一患者的同颌同名牙20对）,将每对同颌同名牙随机分为对照组和试验组。对照组：金属烤瓷全冠牙体预备后直接用氧化锌丁香油水门汀黏固暂时冠;试验组：在牙预备体上涂布极固宁TM后用氧化锌丁香油水门汀黏固暂时冠。分别于牙体预备后1、2周局麻下拔除同颌同名研究牙。常规组织病理切片,HE染色,显微镜下观察评价牙髓组织反应并测量颊侧髓角的剩余牙本质厚度。结果 金属烤瓷全冠牙体预备后1、2周时,试验组与对照组的牙预备体颊侧髓角的剩余牙本质厚度差异均无统计学意义（P > 0.05）。活髓基牙全冠牙体预备后1周,对照组的牙髓组织炎症反应比试验组严重（P < 0.05）;而牙体预备后2周,对照组与试验组的牙髓组织反应差异无统计学意义（P > 0.05）。不论是金属烤瓷全冠牙体预备后1周或2周,所有样本均未见第三期牙本质的形成。 结论 极固宁TM在金属烤瓷全冠牙体预备后1周时可降低活髓基牙牙髓组织的炎症反应。     

不同轴壁聚合度的金属全冠固位力的比较

目的比较3种轴壁聚合度全冠的固位力,探讨其固位效果。方法选用离体上颌前磨牙,进行4°、8°和12°的预备,翻制合金代模,制作金属全冠。比较其粘固前、后的固位力。结果粘固前,4°预备体的全冠脱位力值(177.35±17.13)N,明显大于8°组(102.95±13.66)N和12°组(51.80±9.51)N;粘固后,4°预备体的全冠脱位力值(346.60±30.93)N明显大于8°组(247.95±20.64)N和12°组(216.05±17.35)N。粘固后,4°组脱位力值提高了95.4%,8°组提高140.8%,12°组提高317.1%。结论轴壁聚合度越大,全冠固位力越小。粘固后,轴壁聚合度越大,固位力增幅越大。     

氟保护剂和极固宁TM对活髓基牙预备后牙本质过敏症的防治效果

目的评价氟保护剂和极固宁TM对烤瓷冠桥活髓基牙预备后牙本质过敏症的防治效果.方法对118例246颗活髓基牙预备后,随机分为3组,即氟保护剂组(实验Ⅰ组)、极固宁TM组(实验Ⅱ组)和临时冠组(对照组),分别用氟保护剂+临时冠、极固宁TM+临时冠和临时冠处理,观察其处理后的脱敏效果.采用F检验进行统计学分析(DPS数据处理系统V6.01).结果脱敏后1周,烤瓷冠桥黏固时和1个月后的疗效,实验Ⅰ、Ⅱ组与对照组均有着显著性差异(P＜0.05);而实验Ⅰ组和实验Ⅱ组均无显著性差异(P＞0.05).结论氟保护剂和极固宁TM对预防烤瓷冠桥活髓基牙预备后牙本质过敏有着较为理想的疗效,其操作简单,值得推广应用.     

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目的    研究颈袖不同预备方式对全冠固位力的影响。方法    选取上颌离体切牙40颗,均为2009年8月至2010年2月杭州口腔医院收治的牙周病患者因松动无法保留而拔除的牙齿。根据颈袖不同预备方式随机分为A、B、C、D组,每组10颗牙。对离体牙牙冠舌侧颈1／3进行研磨形成0°（A组）、2°（B组）、5°（C组）切向聚合度的颈袖;D组为对照组,无颈袖存在。在2343型电子万能测试机上,测量拉力与牙体长轴方向夹角为0°和15°时冠脱位所受到的最大拉力值。结果    不同拉力方向下,A、B、C组的固位力明显高于D组,差异均有统计学意义（P < 0.05）。拉力与牙体长轴方向的夹角为0°时,A、B、C组的固位力随着切向聚合度的增加而降低,A组固位力与B组之间差异无统计学意义（P > 0.05）,而与C组间差异有统计学意义（P < 0.05）;拉力与牙体长轴方向的夹角为15°时,A、B、C组的固位力也随着向聚合度的增加而降低,差异均有统计学意义（P < 0.05）。结论    颈袖预备有利于全冠的固位,特别适合于抵抗全冠的旋转脱位。     

The effect of endodontic access cavity preparation and subsequent restorative procedures on molar crown retention

Preparation of an endodontic access cavity through a full crown may affect its retention. This study was undertaken to investigate the effects on molar crown retention of endodontic access cavities and their subsequent restoration. Thirty human molars were mounted in resin, crown preparations were cut and their surface areas were determined. Vented metal copings were cemented with zinc phosphate and the forces required to displace each coping were measured using a tensile-testing machine. The copings were recemented, access cavities were cut and their surface areas determined prior to the displacement forces being re-measured. The copings were recemented, assigned to two groups, and the access cavities were restored - Group 1 with amalgam; Group 2 with glass ionomer (GIC). Displacement forces were re-measured and the copings were recemented. The occlusal margins of the access cavities were ***bevelled and restored again prior to displacement forces being re-measured. Mean displacement forces were -Group 1: Original (kg force), 37.86 ± 3.97; After access cavity, 29.28 ± 3.22; Amalgam, 50.21 ± 4.71; Amalgam + bevel, 46.45 ± 6.21. Group 2: Original, 42.77 ± 4.49; After access cavity, 39.25 ± 5.91; GIC, 48.11 ± 3.55; GIC + bevel, 39.63 ± 5.31. Statistical analyses with paired t tests showed that retentive values with access cavities were significantly lower than with intact crowns. Amalgam or GIC restorations increased retention beyond original values, significantly with amalgam. Bevelled occlusal margins decreased retention of crowns with restored access cavities but this was not significantly different from the original values. A significant relationship existed between total surface areas of the crown preparations, areas of the occlusal tables, and retentive values for crowns without access cavities. The access cavity area, as a proportion of the total area of the preparation, was related to the decrease in retention.     

Effect of preparation convergence on retention and seating discrepancy of complete veneer crowns

The purpose of this study was to evaluate the retention and marginal seating discrepancy of complete veneer crown cemented with zinc phosphate using various preparation convergence designs. The method employed was that of cementing cast metal crowns onto 46 metal dies fabricated as complete veneer crown preparations with various convergence angles ranging from 0 degrees to 70 degrees and a shoulder finish line. The marginal discrepancy was calculated by measuring the change in crown height before and after cementation using an optical measuring microscope. The force required to remove the crowns from the dies in a vertical direction was determined using an Instron universal testing machine and recorded as retention. The increase in preparation convergence exhibited a wide variation of seating discrepancy between specimens, ranging from 4.58 +/- 1.13 to 73.13 +/- 78.32 microm. Significant tilting of crown was observed as the convergence angle of preparation increased. The retention values ranged from 4.03 +/- 0.61 to 12.12 +/- 0.33 MPa. The Pearson analysis revealed statistically significant correlations between preparation convergence and marginal discrepancy (r = +0.62), and retention (r = -0.91). Complete veneer crown retention and marginal discrepancy were influenced by the preparation convergence design.     

Effect of preparation convergence on retention and seating discrepancy of complete veneer crowns

summary   The purpose of this study was to evaluate the retention and marginal seating discrepancy of complete veneer crown cemented with zinc phosphate cement using various preparation convergence designs. The method employed was that of cementing cast metal crowns onto 46 metal dies fabricated as complete veneer crown preparations with various convergence angles ranging from 0° to 70° and a shoulder finish line. The marginal discrepancy was calculated by measuring the change in crown height before and after cementation using an optical measuring microscope. The force required to remove the crowns from the dies in a vertical direction was determined using an Instron universal testing machine and recorded as retention. The increase in preparation convergence exhibited a wide variation of seating discrepancy between specimens, ranging from 4·58 ± 1·13 to 73·13 ± 78·32  μ m. Significant tilting of crown was observed as the convergence angle of preparation increased. The retention values ranged from 4·03 ± 0·61 to 12·12 ± 0·33 MPa. The Pearson analysis revealed statistically significant correlations between preparation convergence and marginal discrepancy ( r  = +0·62), and retention ( r  = −0·91). Crown retention and marginal discrepancy were influenced by the preparation convergence design.     

The effect of endodontic access cavity preparation and subsequent restorative procedures on incisor crown retention

Endodontic treatment often will require access through existing crowns. This study was undertaken to determine whether endodontic access cavity preparation affected the retention of crowns in anterior teeth and then to determine whether this retention can be regained by amalgam or post-retained amalgam restorations. Twenty extracted human incisors were mounted in acrylic blocks and prepared for crowns. Metal copings were fabricated and cemented with zinc phosphate cement and the forces required to displace the copings after various procedures were measured with a tensile testing machine. Retention values for all stages were compared with the initial retentive value for each coping without an access cavity which was set at 100 per cent. Group one specimens had the following means: copings with access cavity, 85.64 ± 28.65 per cent of the initial values; amalgam flush with lingual dentine, 95.81 ± 36.2 per cent; amalgam flush with coping, 114.89 ± 34.5 per cent. Group two means were: copings with access cavity, 89.95 ± 21.42 per cent; posts and amalgam, 177.37 ± 77.5 percent. Statistical analysis with the two sample f test showed that retention with post-retained amalgam restorations showed significantly higher values when compared with access cavities without restorations (p<0.05). Retention values for post-retained restorations were significantly different from those just using amalgam. This study demonstrated that endodontic access cavities reduced the retention of the crowns, and subsequent restoration with amalgam or a post can regain the retention. Post-retained restorations showed the highest retention when compared with the amalgam restorations, but the high standard deviation in the post group indicates that the amount of retention to be gained may be clinically unpredictable.     

The effects of die-Spacidng on post-cementation crown elevation and retention

This paper reviews the relevant dental literature concerning the effect fo die-spacing on crown elevation and pre- and post-cementation crown retention. Techniques of providing die-spacing and measurement of the thickness of the role of the provision of a cement space in reducing post-cementation crown elevation is presented. Factors which may affect crown retnetion prior to and following cementation are also reviewed. The influence of variables in techniques and experimental design on the results of the studies reviewed is discussed.     

二氧化锆全瓷冠在前牙美容修复中的应用

目的:探讨二氧化锆全瓷冠在前牙美容修复的应用。方法:选择58例患者的86颗前牙,二氧化锆全瓷冠修复,观察1年。结果:86颗二氧化锆全瓷冠在修复完成第1天及6个月五项评价指标均达到A级(100%),12个月边缘完整性(97.6%)和牙龈状况(97.6%)达到B、C级各1例。结论:二氧化锆全瓷冠在前牙美学修复中的临床效果较理想。     

脱敏剂对全冠固位的影响

目的:研究极固宁脱敏剂对全冠固位的影响。方法:将20颗离体磨牙牙冠制备成颈部直径8mm、高3mm、聚合度为6度、具备宽0.5mm的90度肩台预备体,制作镍铬合金全冠,将标本随机分为两组,I组在粘结前涂极固宁,II组在粘结前不涂极固宁,用聚羧酸锌水门汀粘固,在生理盐水中保存24小时后测得使全冠脱位时的最大拉力。结果:两组全冠脱位时的最大拉力分别为416.176±27.492 N和436.120±28.877N,经统计学分析二者无显著性差异。结论:极固宁对聚羧酸锌水门汀粘结的全冠的固位力没有影响。