卡环弹性形变限度的测试与临床意义

目的：探讨三种常用金属卡环弹性形变与卡环进入倒凹量的关系。方法：使用作者与有关人员自行设计的卡环张开位移钳,电子万能材料测试仪测试三种金属卡环弹性形变。结果：不锈钢丝卡环弹性最高,１８－８铬镍合金铸造卡环弹性较差,钴铬合金铸造卡环弹性最小。结论：不锈钢丝磨牙卡环进入倒凹量可大于０．５ｍｍ,双尖牙环进入倒凹量０．５ｍｍ,铸造合金磨牙卡环进入倒凹量应小于０．５ｍｍ,铸造合金双尖牙卡环进入倒凹量应小于０     

钴铬合金铸造卡环弹性形变限度及相应卡抱力的研究

目的:研究钴铬合金铸造卡环的弹性形变限度及其相应卡抱力。方法:将由3个不同厂家生产的钴铬合金制得的铸造卡环在万能材料试验机上进行加载-形变测试,计算机自动采集测试过程中的加载-形变曲线,曲线经一系列软件处理、计算后最终获得卡环在比例极限内的弹性形变限度及相应卡抱力。结果:3种钴铬合金铸造卡环的弹性形变限度不尽相同,但其相应卡抱力的差别无统计学意义。在测试卡环的长度为10.0mm、卡环支撑处的厚度和宽度分别是(0.96±0.02)mm和(1.71±0.02)mm时,3种卡环的弹性形变限度范围是0.32～0.36mm,其相应卡抱力的范围是9.31～10.47N。结论:钴铬合金铸造卡环进入基牙的倒凹深度应以0.25mm为宜。     

树脂卡环与Co-Cr卡环的脱位力及体外循环疲劳测试

目的:比较树脂卡环与Co-Cr卡环在循环疲劳测试中的脱位力及其衰减趋势。方法:制作树脂和Co-Cr卡环,在基牙0.25mm和0.50mm两种倒凹深度下,利用多功能生物力学测定仪进行循环疲劳测试,对比其脱位力大小及衰减情况,同时测试各卡环的形变距离。结果:卡环在循环疲劳测试后其脱位力都不同程度的下降,脱位力下降最明显的是Co-Cr卡环0.50mm倒凹组,达6.937N,最小的是树脂卡环0.25mm倒凹组,为0.050N;循环测试前后2种倒凹深度下Co-Cr卡环组脱位力差异显著,树脂卡环组脱位力差异无统计学意义;Co-Cr卡环组的形变距离大于树脂卡环组。结论:树脂卡环固位力较Co-Cr卡环小,但衰减缓慢、形变小。     

缩醛树脂卡环与钴-铬卡环的固位力和形变的比较

缩醛树脂卡环具有很好的美观性，能满足固位卡环、连接体和可摘局部义齿支架制作的需要。本研究的目的是比较缩醛树脂卡环与钴一铬卡环在模拟临床使用36个月后的固位力和形变大小。     

弹性卡环基托义齿制作可能出现的问题及对策

弹性卡环基托义齿（隐形义齿）采用高弹性、抗折力强,生物安全性好的高分子弹性材料。材料和色泽与龈组织接近,有一定的透明性并有仿血管的纤维,替代了传统义齿的基托和金属卡环部分。该义齿的基托薄而富于弹性,患者佩戴舒适;义齿的卡环亦由基托材料铸压形成,美观,誉为隐形义具,深受患者的欢迎。我科使用Ｖａｌｐｌａｓｔ弹性基托材料。为单个牙或多个牙缺失患者,也为整铸支架的可摘局部义齿制作弹性基托和部分固位卡环,已完成５４例,取得了良好的效果。现提出制作工艺中可能出现的一些问题,和个人处理意见,并作了讨论,仅供参…     

卡环固位力与基牙倒凹深度的关系

目的 了解卡环固位力与基牙倒凹深度间的变化关系，为卡环设计获得最佳效果提供依据。方法 采用Chatillon测力仪，测定临床常用钴铬合金铸造三臂卡，在前磨牙、磨牙的0．25mm、0．50mm、0．75mm三个倒凹深度上的固位力。结果 倒凹深度越大，卡环固位力也越大；相同倒凹条件下，磨牙卡环的固位力比前磨牙卡环大。不同基牙、不同倒凹深度对于卡环固位力均存在显著影响。结论 在材料弹性极限内，卡环固位力与进入基牙深度成正变关系。     

弹性树脂卡环铸造部件结合式义齿的临床应用

牙列缺损是口腔修复临床的常见和多发性缺损畸形[1]。在牙列缺损的诸多修复方法中，活动义齿是牙列缺损最常见的方法，但常规可摘局部义齿，存在美观和发音上的不足，许多患者难以接受。弹性树脂卡环铸造部件结合式义齿，是应用弹性树脂材料制作前牙及双尖牙区卡环、基托，而连接杆、支托、磨牙区卡环及小连接体等非弹性部位，采用铸造方法制作的可摘局部义齿。作者从1998年到2000年，对60例患者62件义齿用此方法修复，临床应用证明，能获得满意的修复效果。现介绍如下：1.材料和方法1.1一般资料修复60例患者共62件义齿，男性24例，女性36例…     

树脂卡环固位力和形变的体外研究

目的研究树脂卡环固位力和形变的大小。方法整体铸造前磨牙和磨牙试件各40个,倒凹计测定出0.25 mm和0.50 mm的倒凹。根据基牙类型和倒凹深度,将试件分为4组：0.25 mm倒凹前磨牙组、0.50 mm倒凹前磨牙组、0.25 mm倒凹磨牙组、0.50 mm倒凹磨牙组,每组20个试件。每组试件分别制作树脂三臂卡和Co-Cr合金三臂卡各10个。将卡环戴入相应的基牙并浸泡于去离子水中,测定在0、720、1 440、2 160、2 880、3 600、4 320次连续取出和戴入循环周期时卡环的固位力,并记录0和4 320次循环周期时卡环固位臂卡环尖和抗力臂卡环尖之间的距离。结果1）树脂卡环的平均固位力为1.69 N,低于Co-Cr卡环的平均固位力5.87 N（P<0.01）。在其他因素相同的情况下,树脂卡环的固位力小于Co-Cr卡环的固位力（P<0.01）,磨牙卡环的固位力小于前磨牙卡环的固位力（P<0.01）,0.25 mm倒凹卡环的固位力小于0.50 mm倒凹卡环的固位力（P<0.01）。随着循环次数的增加,Co-Cr卡环的固位力显著降低（P<0.01）,而树脂卡环的固位力无显著变化（P＞0.05）。2）4 320次循环周期后,Co-Cr卡环的固位臂卡环尖和抗力臂卡环尖之间的距离显著增加（P<0.05）,而树脂卡环的固位臂卡环尖和抗力臂卡环尖之间的距离无显著变化（P＞0.05）。结论树脂卡环的固位力和形变均明显低于铸造卡环。     

RPI卡环的改良设计

描述了改良ＲＰＩ卡环的设计,并与传统的ＰＲＩ卡环相比较,改良ＲＰＩ卡固位尖端只需进入基牙颊面最远的较小倒凹则可获得听固位,而且更美观,同时也符合远中游离鞍基围绕近中Ｈｅ支托转下沉中,Ｉ杆固位尖端与基牙脱离接触原则。因此发言奶卡环可小或避免伟给基牙持力,量种适用远中淳离端可摘局部义齿的新型止环设计。     

卡环的研究进展

卡环目前仍然是可摘局部义齿修复牙列缺损的常用固位体。本综述对近年来国内外在这方面的研究进行了总结和概括,内容集中在如何选择合适的卡环材料、数目和外形等方面,并提出了一种卡环制作的标准化模式。     

The effect of thermo-mechanical fatigue on the retentive force and dimensional changes in polyetheretherketone clasps with different thickness and undercut

PURPOSEEsthetic expectations have increased the use of polyetheretherketone (PEEK) clasps as alternatives to Cr-Co in removable partial dentures (RPDs). The objective of this study was to evaluate the retentive force and dimensional change of clasps with different thickness and undercut made from PEEK by the thermo-mechanical fatigue.MATERIALS AND METHODSPEEK clasps (N = 48) with thicknesses of 1 or 1.50 mm and 48 premolar monolithic zirconia crowns with undercuts of 0.25 mm or 0.50 mm were fabricated. Samples are divided into four groups (C1-C4) and were subjected to 7200 thermal aging cycles (at 5 - 55℃). The changes in the retentive force and dimensions of the clasps were measured by micro-stress testing and micro-CT devices from five measurement points (M1 - M5). One-way ANOVA, paired t-test, two-way repeated ANOVA, and post-hoc tests were used to analyze the data (P < .05).RESULTSThe retentive forces of C1, C2, C3, and C4 groups in initial and final test were found to be 4.389-3.388 N, 4.67 - 3.396 N, 5.161 - 4.096 N, 5.459 - 4.141 N, respectively. The effects of retentive force of all PEEK clasps groups were significant decreased. Thermo-mechanical cycles caused significant dimensional changes at points with M2, M4, and M5, and abraded the clasp corners and increased the distance between the ends of the clasp, resulting in reduced retentive forces (P^* = .016, P^* = .042, P < .001, respectively).CONCLUSIONThermo-mechanical aging decreases the retentive forces in PEEK clasps. Increasing the thickness and undercut amount of clasps decreases the amount of dimensional change. The values measured after aging are within the clinically acceptable limits.     

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目的探讨上颌切牙区基牙牙冠高度和唇侧倒凹深度对弹性义齿固位的影响。方法选择2009年1月至2011年5月来佛山禅城区口腔医院修复科就诊的212例上颌单颗中切牙缺失患者进行弹性义齿修复。在弹性义齿戴用的当天及3、6个月后测量各基牙的牙冠高度和唇侧倒凹深度,并检查义齿固位情况。结果弹性义齿在固位良好和固位不良两种情况下的基牙牙冠高度及唇侧倒凹深度的差异均有统计学意义(P<0.05)。结论弹性义齿修复前应对两侧基牙的牙冠高度和唇侧倒凹深度进行综合评价。     

Aulen树脂卡环与Co—Cr卡环循环疲劳及对牙面磨损的研究

目的：比较Aulen树脂卡环与Co—Cr卡环在离体牙上循环疲劳测试中的脱位力衰减趋势,观察其对离体牙的磨损。方法：制作Aulen树脂卡环和Co—Cr卡环,利用多功能生物力学测定仪进行循环疲劳测试,对比其脱位力衰减情况,扫描电镜观察实验前后离体牙的磨损情况;结果：卡环在循环疲劳测试后其脱位力均不同程度下降,Aulen树脂卡环的摩擦区域无明显划痕,Co—Cr卡环的摩擦区域形成明显的划痕,破坏了原来平滑的表面。结论：Aulen树脂卡环固位力较Co—Cr卡环小,但衰减缓慢,Aulen树脂卡环对牙面的磨损程度小于Co—Cr卡环。     

卡环设计与基牙牙槽骨及剩余牙槽嵴吸收关系的研究

目的 研究铸造支架式可摘局部义齿卡环设计与基牙牙槽骨及剩余牙槽嵴吸收之间的关系。方法 选择牙列远中游离缺失的患者55例,基点末端基牙采用RPI型卡环13例,PRA型16例、传统三臂卡环26例,于义齿修复当时以及修复后6月和12月时,拍摄该末端基牙的定位X线根尖片,并进行数字减影分析,计算末端基牙牙槽骨及剩余牙槽嵴的骨吸收参考体积量。结果 （1）剩余牙槽嵴以及末端基牙颊舌侧牙槽嵴顶的吸收;RPA组低于RPI组和传统三臂卡环组;（2）末端基牙远中牙槽嵴顶的吸收;RPA组和RPI组低于传统三臂卡环组。结论 近中He支托设计的卡环,较远中He支托设计的卡环,有利于维护末端基牙远中牙槽骨的健康;RPA型卡环设计较RPI和传统三臂卡环设计更利于维护末端基牙颊舌侧牙槽骨以及剩余牙槽嵴的健康。     

The relationship between test methodology and elastic behavior of composites

Comparisons were made of the Young's moduli obtained with tests that impose static, low-frequency, or high-frequency elastic deformations on dental composite systems. The frequency of the imposed stress was reflected in the absolute value of Young's modulus. However, the values obtained at different test frequencies could be compared and understood by taking into account this frequency dependence. It was thus found that the composite structure largely determined the type of reaction to the imposed stress. The fundamental period test permitted the greatest differentiation in the elastic behavior of the investigated composites.     

Effect of different materials and undercut on the removal force and stress distribution in circumferential clasps during direct retainer action in removable partial dentures

ObjectivesThis study aimed to evaluate the effect of different materials and undercut on the removal force and stress distribution in the supporting tooth and in the circumferential clasp used in removable partial prosthesis.MethodsUpper molars prepared for Akers circumferential clasp with retention and opposing arm were modeled, scanned, elaborated with CAD software and the geometries imported in FEA and analyzed. Six different materials were selected for the clasp (Polyamide, Polyoxymethylene, Polyetheretherketone - PEEK, Gold alloy, Titanium and CoCr) and 3 different undercuts (0.25, 0.50 and 0.75 mm), totaling 18 groups.ResultsThe clasps presented greater stress in their structure and potentially greater damage to the dental enamel when made with rigid materials and with more undercut; however, they presented greater ability to remain in position.SignificancePolyamide with a higher undercut is an esthetic alternative to rigid metallic clasps. It showed promising behavior because it strongly reduces the damage to the enamel, and even with an undercut of 0.75, the retention is lower than for CoCr with a 0.25 undercut, and this retention might still be sufficient. Polyoxymethylene and Polyetheretherketone (PEEK) are not suitable materials for the clasps, because the maximum stress occurring during removal with higher undercuts is higher than the material strength.     

新鲜牛牙周膜不同部位与弹性模量的关系研究

目的：研究牛牙周膜不同部位对弹性模量的影响。方法：选取成年牛磨牙制成标准牛牙周膜试件。通过万能材料测试系统测定同一磨牙不同部位试件中牙周膜的弹性模量。结果：牛牙周膜弹性模量并不是均匀一致的,根中部牙周膜的弹性模量值最高,牙颈部次之,牙根处牙周膜的弹性模量最小。结论：牛牙周膜弹性模量从牙颈部到根中部呈增大趋势,到根中部呈最大值,向根尖部层递减趋势。     

The relationship between dietary sugar experience and the quantity and biochemical composition of dental plaque in man.

The calcium and inorganic phosphorus concentrations of 2-day plaque in adults were inversely related to the previous dietary sugar experience; the dry weight and concentrations of water-soluble and alkali-insoluble carbohydrate were directly related to the dietary sugar experience. However, the relationship with the diet appeared to be limited to carbohydrate concentrations in mature plaque from children.