四种粘固剂条件下两种阶梯形核桩钉固位力的研究

目的比较两种阶梯形核桩钉在四种粘固剂条件下与模拟根管的固位力.方法将两种阶梯形核桩钉各制作20个试件,随机分为4组,在四种粘固剂条件下测试其与模拟根管的固位力.结果研制的核桩钉固位力明显高于Optipost核桩钉且存在显著差异(P<0.05).四种粘结剂间的固位力存在显著差异(P<0.05).结论研制的阶梯形核桩钉的固位力优于进口的Optipost阶梯形核桩钉,可在临床推广应用.     

FRC桩钉与两种金属核桩对无髓牙抗折性能影响的对照研究

目的 :比较用 3种桩钉修复后无髓牙的抗折力 ,评价FRC桩钉对无髓牙抗折性能的影响。方法 :用FRC桩钉加树脂核、Ni Cr合金桩核和钛合金桩核修复离体无髓牙根 ,在万能力学试验机上测试 13 0°加载时的破坏载荷。结果 :FRC桩钉组的破坏载荷小于Ni Cr合金桩核和钛合金桩核组 [分别为 (2 76.6±15 .1)N ,(3 94.7± 2 9.1)N ,(3 73 .4± 5 3 .8)N] ;合金核桩组的破坏形式均为牙根的折裂 ,而FRC桩钉组为核的碎裂。结论 :FRC桩钉可以满足临床需要 ,结合树脂核修复有利于保护牙根。     

预成根管钉铸造桩修复后的牙根抗折力实验研究

目的:比较相同条件下前后牙铸造桩核和预成根管钉修复后牙根的抗折力。方法:在离体牙根上用铸造桩核或预成根管钉修复后,通过电子万能材料试验机测定载荷抗压强度。结果:前牙预成根管钉和铸造桩核修复二组间抗压强度差异有显著性差异(P<0.05);后牙预成根管钉和铸造桩核修复二组间抗压强度差异无显著性差异(P>0.05)。结论:前牙铸造桩核修复后的牙根比预成根管钉修复后的牙根具有更大抗折力;后牙二种修复后抗折力相同。     

桩核材料与纤维/树脂复合材料桩钉联合修复无髓牙的抗折性能研究

目的评价3种树脂类桩核材料与高强玻璃纤维/树脂复合材料(FRC)桩钉联合修复无髓牙的抗折性能。方法用FRC桩钉和3种经不同方法处理(热压和未热压)的树脂核(Artglass聚合体、Charisma复合树脂、AB组份复合树脂)联合修复离体无髓牙根,测试1300加载时的破坏载荷。结果Artglass聚合体组的抗折力最高(505.4N),经热压处理后强度明显提高(564.1N) ; Chari~复合树脂组经热压后脆性增加,强度降低(热压前后分别为411.3N和 315.3N); AB组份树脂组经热压后强度明显提高(热压前后分别为358.4N和423.4N)。实验中无1例出现桩钉折断和聚酷冠碎裂。结论不同桩核材料与FRC桩钉联合修复无髓牙的抗折力不同,其中Art乡ass聚合体组的抗折力最高,但是此3组的抗折力均超过了咀嚼过程中前牙的咬合力,树脂核与纤维/树脂复合材料桩钉联合修复无髓前牙残根可以满足临床需要。     

不同预成桩钉在离体牙根内的固位力比较

桩冠是利用金属冠桩插入根管内以获得固位的一种冠修复体。由于牙髓治疗广泛而有效地开展 ,使大量严重缺损的患牙和残根得以保留和修复 ,桩冠修复有了可靠的基础。桩冠的成败主要取决于桩的固位力 ,而预成桩钉的出现虽然为桩冠的制作提供了简单而实用的方法 ,但要使预成桩获得良好的固位 ,就必须进一步增强和改善它的固位措施。因此 ,学者们通过改变桩的形态、长度、直径来提高预成桩的固位力 ,由此而产生了各种不同的冠桩系统。本实验旨在通过研制的阶梯形核桩钉 ,顶角为 60°[1] 的螺纹形核桩钉与不同品牌、形态的阶梯钉和螺纹、柱状钉对…     

介绍两种新型预成核桩钉

20世纪 70年代初期 ,人们普遍认为在无髓牙的修复中 ,植入根管内桩可以避免应力集中和根折 ,以保护失去牙髓后逐渐变脆的牙根。随着实验手段的不断更新 ,更多的学者开始认识到 ,防止牙根折产生的主要因素是桩的形态与治疗中所保留的牙本质的量。桩的形态因临床上常用预成桩钉多为直径一致的圆柱形 ,而牙根是锥形 ,这就形成修复过程中根尖区的薄弱部位。所以在核桩钉的设计中 ,采用了阶梯形 ,其逐级缩小的阶段减小了根尖段桩钉的直径 ,可防止根尖区牙体组织折裂 ,对保持牙根较为有利。现有的预成螺纹桩钉的螺纹顶角多数不是 60°。根据黄辉对…     

三种桩核系统修复后离体牙抗疲劳性实验

目的 比较3种不同桩核系统修复的离体牙抗疲劳性差异.方法 30颗离体上颌中切牙,去除牙冠后用镍铬合金金属铸造桩核＋金属烤瓷冠修复（以下简称金属桩组）,进行疲劳实验和抗折实验;同时与平滑型和螺纹型石英纤维桩＋树脂核＋金属烤瓷冠修复的离体牙（以下简称平滑桩组和螺纹桩组）进行比较,记录显微镜下的牙根破损情况和牙冠折断时最大力值.结果 金属桩组、平滑桩组和螺纹桩组牙根的破损率分别为100％、60％和90％.金属桩组牙根破损率较其它2组差异具有统计学意义（P＜0.05）.金属桩组、平滑桩组和螺纹桩组牙根的折断力分别为136.22±41.26 N、133.77±33.12 N和169.44±47.14 N,3组间无显著性差异（P＞0.05）.结论 纤维桩较金属桩能够降低牙根破损率,但3种桩修复离体牙抗折力之间没有明显差异.     

新型高强度玻璃离子水门汀修复漏斗状残根的实验研究

目的：探讨应用新型高强度玻璃离子水门汀对漏斗状残根的修复效果。方法：将45个完整的上颌离体中切牙预备成漏斗状残根，随机分成3组，A组：新型高强度玻璃离子水门汀核联合成品金属螺纹桩修复。B组：双重固化型复合树脂核联合成品金属螺纹桩修复。C组：Ni-cr合金铸造桩核修复。将样本固定于电子万能测试仪上，测试抗折强度并观察折断模式。结果采用方差分析、X^2检验。结果：新型高强度玻璃离子水门汀组的牙根抗折强度已达到较高水平，与双重固化型复合树脂组的牙根抗折强度并无显著性差异，而这两组的牙根抗折强度虽然低于Ni-cr合金铸造桩核组，但其折断模式更有利于牙根的重复利用。结论：应用新型高强度玻璃离子水门汀核联合成品金属螺纹桩可用来修复漏斗状残根。     

两种桩核冠修复下颌前磨牙的抗折力研究

目的研究两种桩核修复不同牙本质领圈的下颌前磨牙的抗折性能,为临床应用提供实验依据。方法选取离体下颌恒前磨牙48颗,随机分为6组,A组~F组,每组8颗。所有牙经根管治疗后齐釉牙本质界上2 mm截冠。A、B组保留2 mm完整的牙本质壁;C、D组保留舌侧一半牙本质壁;E、F组则保留颊侧一半牙本质壁。然后A、C、E组行铸造桩核冠修复,B、D、F组行金属螺纹桩树脂核全冠修复。在万能测试机上进行加载,记录断裂时的最大载荷。结果各组平均最大载荷值大小趋势为A>B>C>E>D>F。A、B组之间比较P>0.05。C、E组之间比较P>0.05;D、F组之间比较P>0.05。C、D组之间比较P<0.05,E、F组之间比较P<0.05。试件折裂形式大部分为斜向根折,有利于再修复的折裂只出现在螺纹桩树脂核组中。结论根管治疗后的下颌前磨牙保留2 mm的完整牙本质领圈,桩核材料性能对牙体抗折力没有显著影响;同种桩核冠修复牙体,缺损范围对牙体的平均抗折力无明显影响;不完整领圈组铸造桩核冠修复后牙体的平均抗折力大于金属螺纹桩树脂核全冠组,以接近牙本质弹性模量的的复合树脂做核材料有利于保护牙根。     

膨胀方式和膨胀量对核桩冠粘结膨胀复合型螺纹桩抗折力的影响

目的：研究膨胀方式和膨胀量对核桩冠膨胀复合型螺纹桩抗折力的影响。方法：以标准尺寸的有机玻璃模拟上中切牙牙根88个，用不同规格的金属分瓣器制作三叶塑胶膨胀套，以两种不同膨胀方式将相同直径的螺纹桩和不同尺寸的膨胀套同时，以磷酸锌旋转拧入膨胀粘固。在INSTRON4302万能测试机进行压缩测试，加载速度1mm／min，至桩核松动，脱位或牙根破裂，记录最大载荷。结果：不同膨胀方式间抗折力大小有明显差异（P〈0．05），相同膨胀量不同膨胀方式间抗折力有明显差异（P〈0．05），不同膨胀量相同膨胀方式组内抗折力大小有明显差异（P〈0．05），膨胀量在10％以内时，抗折力最大。结论：临床应用膨胀复合型螺纹桩时，应采用一定的膨胀方式，且应当将膨胀量控制在10％以内和螺纹桩拧入到预备根管底部。     

Posts and cores: when to use them

The two overriding factors for successful post restoration are: 1. Retention, i.e., resistance to torsional forces. Published research is clear that threaded posts are the method of choice for the restoration of endodontically treated teeth in order to achieve optimal success. Prethreaded and self-threaded are the two systems from which to choose. The words active and passive should be applied to the method of producing threads, not the posts. The most gentle way to produce a thread is with a thread cutter. 2. Stress distribution of some cylindrical threaded posts has been shown to be far superior to nonthreaded cylindrical and nonthreaded tapered posts. With the acceptance of threaded, cylindrical prefabricated posts, new terminology has evolved, and the use and meaning of these words has been made more precise.     

Effects of post system and length on the strain and fracture resistance of root filled bovine teeth

Aim To investigate ex vivo the effects of different post systems and lengths on the strain and fracture resistance of root‐filled teeth. Methodology One hundred and thirty‐five bovine incisors were sectioned 15 mm from their apices, root‐filled and divided into three groups (n = 45): fibreglass post; prefabricated steel post; cast post and core. Each group was divided into three subgroups (n = 15) according to the post length: 5.0 mm; 7.5 mm; 10.0 mm. All teeth were restored with metal crowns. For strain‐gauge measurement, two strain gauges per sample were used. The fracture resistance (N) was measured and the data were analysed with two‐way analyses of variance, followed by the Tukey’s HSD test (α = 05). Results For all posts, decreased lengths resulted in increased microstrain values. However, the fibreglass posts were associated with lower increases when compared with cast post and cores and prefabricated steel posts, which showed microstrain values two times higher when the post length was 5.0 mm. The two‐way analyses of fracture resistance values revealed that post length was statistically significant for the metal posts and not significant for the fibreglass post. The fracture mode analysis indicated that all groups tended to demonstrate root fractures in groups restored with metal posts and resin core fractures in groups restored with fibreglass posts. Conclusions The cast post and core when the length was 10.0 mm had the highest fracture resistance; however, the fibreglass post was effective with the three post lengths, with higher fracture resistance than metal posts when the length was 5.0 mm.     

Effect of post adaptation on fracture resistance of endodontically treated teeth

This study determined the effect of different post designs and varying amounts of post-to-canal adaptation on the fracture resistance of endodontically treated teeth. Forty freshly extracted maxillary central incisors were endodontically treated. Groups of 10 teeth were prepared according to four experimental designs. Cast post and cores and crowns were waxed, cast, and luted with zinc phosphate cement on a static loading device. The teeth were embedded in acrylic resin and the crowns were loaded on a universal testing machine at 130 degrees to the long axis of the tooth until failure. Maximum adaptation of the residual root structure with a tapered post significantly increases the fracture resistance of endodontically treated teeth, but upon failure renders the tooth nonrestorable. Tapered posts resulted in fractures that were directed more apically and lingually. Parallel-sided posts had a lower frequency of fracture upon failure, involving less tooth structure. Parallel-sided posts surrounded by large amounts of cement had no significant effect on failure loads.     

In vitro fracture resistance of premolar teeth restored with fibre‐reinforced composite posts using a single or a multi‐post technique

The purpose of this study was to evaluate the reinforcing effect of fibre‐reinforced composites (FRC) applied in premolar teeth with different techniques and minimally invasive post space preparation. Fifty extracted and endodontically treated premolar teeth were used. The teeth were divided into five groups (n = 10) depending on the restorative technique (Groups 1–5). Group 1: one single conventional post, Group 2: one main conventional and one collateral post, Group 3: one elastic post, Group 4: one main elastic and one collateral post, and Group 5: individual post formed of elastic posts. After cementation and core build‐up, the specimens were submitted to static fracture resistance test. Fracture thresholds and fracture patterns were measured and evaluated. Group 4 showed the highest average fracture resistance among the tested groups. The multi‐post techniques (group 2 and 4) exhibited statistically higher fracture resistance compared to group 1. Regarding fracture patterns, there was no statistically significant difference between the tested groups. Within the limitations of this study, the application of multiple elastic or conventional FRC posts or a single elastic post in the same root canal is beneficial in terms of fracture resistance compared to a single conventional FRC post. The elasticity or the number of posts did not influence the fracture patterns.     

In vitro fracture resistance and marginal adaptation of metallic and tooth-coloured post systems

The aim of this in vitro study was to compare the fracture resistance and marginal adaptation of all-ceramic incisor crowns with all-ceramic posts, glass-fibre-reinforced posts and titanium posts as well as a control without any post. Three groups of eight maxillary incisors were restored with an all-ceramic post, a fibre-reinforced composite (FRC) post, a titanium post and a further group was restored without posts. Composite cores were provided and all-ceramic crowns were adhesively luted. After artificial ageing, the fracture resistance of the restored teeth was determined. The marginal adaptation of the restorations at the interfaces between cement-tooth and cement-crown was evaluated with scanning electron microscopy using replica specimen before and after ageing. The restored teeth without posts [270N (235/335)] showed no significantly different fracture strength compared with teeth with the titanium system [340N (310/445)]. The all-ceramic posts [580N (425/820)] and the FRC posts [505N (500/610)] both provided a significant higher fracture resistance than the teeth without posts. Prior to ageing, all materials showed <5% separation at the margins cement-tooth or cement-crown ('marginal gap'). After ageing, the interfaces of all systems deteriorated to values between 6 and 14% marginal gap. The greatest marginal gap was found with the titanium system (14%) at the interface cement-crown and with the all-ceramic posts (12%) at the transition between cement-tooth. Regarding fracture resistance and the marginal adaptation, the all-ceramic and FRC posts may be considered as an alternative to the commonly used titanium post restorations.     

In vitro evaluation of the effect of post system and length on the fracture resistance of endodontically treated human anterior teeth

Objectives

The aim of this study was to evaluate the effect of post system and length on the fracture resistance of endodontically treated human anterior teeth.

Material and method

Seventy-five extracted human incisors were endodontically treated, out of which 60 were decoronated 2?mm above the cementoenamel junction and divided into two experimental groups based on the type of post system to be used: glass fiber post (GFP) and Ribbond fiber post groups (RFP). Endodontically treated human anterior teeth in which no post was placed served as control group. Each group was divided into two subgroups according to the length of post space: 5 and 10?mm and all the samples were restored with metal crowns. The fracture resistance was measured by applying loads at an angle of 130° to the long axis of teeth in an Instron universal testing machine.

Results

The results revealed that GFP group at 10-mm post space length showed the significantly highest fracture resistance (740.2133?N) among all groups and subgroups. Decrease in post length resulted in the decrease in fracture resistance in GFP group (425.1867?N), whereas in group RFP 5-mm subgroup (299.6200?N) showed significantly higher fracture resistance than 10-mm subgroup (216.9300?N) but lesser than the control (437.8733?N) in both the subgroups.

Conclusion

Glass fiber posts efficiently increase the fracture resistance of an endodontically treated tooth but the determination of optimal post length is also essential.

Clinical relevance

The present investigation highlights the significance of using glass fiber posts in the restoration of endodontically treated teeth. Endodontically treated teeth restored with glass fiber posts showed increased fracture strength and favorable mode of fracture, and are therefore highly recommended to achieve better clinical outcomes.     

改良金属桩核的临床应用研究

目的：探讨改良金属桩核的临床修复效果。方法：分别制作改良金属桩核（不透明瓷覆盖金属桩核）＋铸瓷全冠,全瓷桩核＋铸瓷全冠,金属桩核＋铸瓷全冠,活髓天然牙＋铸瓷全冠各30例。用Easyshade电脑比色仪检测全瓷冠与天然牙的颜色色差。18个月后临床复查修复体颜色,边缘密合度及松动、脱落、折断情况。结果：改良金属桩核组和金属桩核组均有龈缘返青现象发生,二者间有统计学差异（P〈0.05）。在颜色方面,全瓷桩核组与天然牙组较改良金属桩核组稍接近于天然牙,但无统计学差异。改良金属桩核组、全瓷桩核组与天然牙组均较金属桩核组更接近于患者的天然牙,有统计学意义（P〈0.05）。边缘密合度、松动、脱落、折断情况,4组间无差异。结论：改良金属桩核颜色美观,适应证广泛,价格低廉,工艺简单,临床上可积极推广应用。     

The influence of post length and crown ferrule length on the resistance to cyclic loading of bovine teeth with prefabricated titanium posts

PURPOSE: The purpose of this in vitro study was to evaluate the influence of post and ferrule length on the resistance to cyclic (fatigue) loading of teeth with prefabricated titanium posts (ParaPost) and crowns. MATERIALS AND METHODS: Ninety bovine teeth with similar dimensions were mounted in acrylic blocks with artificial silicone periodontal ligaments. Combinations of post lengths of 5 mm, 7.5 mm, and 10 mm, and ferrule lengths (i.e., the vertical dentinal overlap of the crown) of 0 mm, 1.25 mm, and 2.5 mm made up 9 different groups consisting of 10 teeth each. The posts were cemented with zinc phosphate cement. Composite-resin cores were made and crowns were cemented. Each test specimen underwent cyclic loading of 400 N with a frequency of 1 load per second at an angulation of 45 degrees to the long axis of the tooth. RESULTS: All but 2 specimens failed with a root fracture; in the remaining 2 specimens the core lost retention. A large variation in the results between the various groups was observed. A nonparametric 2-way analysis for groups with a natural order revealed that the fracture resistance to cyclic loading increased statistically significantly with increasing ferrule length (P < 0.01), whereas increasing post length did not increase fracture resistance (P = 0.44). CONCLUSION: Ferrule length was more important than post length in increasing fracture resistance to cyclic loading of crowned teeth.     

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。     

An ex vivo study of the effects of retained coronal dentine on the strength of teeth restored with composite core and different post and core systems

AIM: To investigate the fracture resistance and fracture patterns of teeth restored with composite cores supported by different pre-fabricated post systems and different heights of remaining coronal dentine. METHODOLOGY: Four groups of 30 single rooted teeth were used. Each group was divided into three subgroups of 10 teeth each and restored with carbon fibre, glass fibre, or Radix titanium posts luted with dual cure resin cement. The control group A had no retained coronal dentine. Groups B, C and D had 2, 3 and 4 mm of retained buccal and lingual coronal dentine, respectively. Teeth were tested to failure using an Instron Universal Testing Machine. Subsequently, the fracture mode of specimens was recorded. RESULTS: Teeth with retained dentine were more resistant to fracture (P = 0.001). Tooth fracture resistance was not significantly different between groups B, C and D. Within group A, titanium posts were associated with higher fracture resistance than fibre posts. Within the other groups, tooth fracture resistance was not related to post material. Within groups C and D, fracture resistance of teeth restored with carbon fibre posts was significantly higher than those restored with glass fibre posts. The dominant fracture mode in group A was core and vertical oblique root fracture whilst a combination of core, coronal dentine and root fracture occurred in the other groups. CONCLUSIONS: Fracture resistance of teeth increased with the presence of retained coronal dentine. The use of glass and carbon fibre posts did not improve the fracture resistance or the fracture pattern of teeth when compared with metal titanium posts regardless of the presence of retained coronal dentine. The dominant fracture pattern of teeth was not related to the amount of retained dentine if it was >2 mm high.