三种方式修复严重缺损的上颌中切牙抗折性能研究

目的：比较三种方式修复严重缺损的上颌中切牙的抗折性能,探讨保存残根残冠更合理的修复方式。方法：36颗上颌中切牙随机分为3组,根管治疗后平齐唇侧釉牙本质界垂直与牙体长轴截冠。分别行铸造镍铬合金桩核、铸造镍铬合金桩树脂核及玻璃纤维桩树脂核＋金属全冠修复。在万能测试机进行力学测试,记录最大载荷和断裂模式。结果：3组的抗折强度分别为292.06±155.51N、439.89±89.55N和284.98±133.56N,铸造镍铬合金桩树脂核组明显高于另外2组,差异具有统计学意义。铸造镍铬合金桩均导致牙根垂直折裂,玻璃纤维桩10颗桩折,2颗桩折合并唇侧颈1/3折裂。结论：无箍作用时应充分利用树脂与牙体的粘结作用,高强度的铸造镍铬合金桩较玻璃纤维桩能更好地抵抗外力,结合高强度的树脂核强度更大。     

不同直径预成氧化锆桩和纤维桩修复的抗折性比较

目的观察不同直径预成氧化锆桩和纤维桩与核树脂桩核冠修复上颌中切牙的抗折力。方法 24颗完整上中切牙根管充填后随机分为4组,分别采用直径1.5mm、1.35mm预成氧化锆桩和直径1.5mm、1.375mm预成纤维桩与核树脂加Ni-Cr合金铸造冠修复。对所有样本进行抗折实验,并对其断裂模式进行观察和分析。结果直径1.5mm、1.35mm预成氧化锆桩组抗折力为508.5±143.3N和434.9±141.7N,大于直径1.5mm、1.375mm的预成纤维桩组抗折力(292.2±54.5N,238.5±79.1N),差异有统计学意义(P<0.05)。预成氧化锆桩组样本的损坏模式为桩的断裂或合并根颈部的损伤,根颈部的损伤中50%为破坏性牙折;预成纤维桩组样本的损坏模式为桩的弯曲,根颈部的损伤中83.3%为可修复性牙折。结论预成氧化锆桩与核树脂桩核冠修复上颌中切牙可承受较高的载荷,预成纤维桩对预防破坏性根折有利。     

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。     

不同材料修复喇叭型根管口的实验观察

目的观察不同材料修复喇叭型根管口后的抗折裂强度和破坏模式。方法将15颗离体上颌中切牙截除牙冠后进行常规根管治疗,形成喇叭型根管口,然后随机分为A、B、C组,分别用镍铬合金铸造桩核、预成玻璃纤维树脂桩核和可塑性纤维增强树脂桩核修复。在压力测试机上对试件进行抗折裂强度测试,并记录破坏模式。结果3组试件修复后的抗折裂强度无统计学差异（P＞0.05）,但破坏模式不同,其中A组铸造桩核试件主要表现为根折和粘接剂与牙体分离,B组预成玻璃纤维树脂桩核试件主要表现为桩与粘接剂分离,C组可塑性纤维增强树脂桩核试件主要表现为粘接剂与牙体组织分离。结论纤维树脂类修复材料修复喇叭型根管口有利于残根的保存和再次修复。     

CAD/CAM一体化玻璃纤维桩核抗折力的体外实验研究

目的比较CAD/CAM一体化玻璃纤维桩核与预成纤维桩和铸造金合金桩核修复体的抗折力。方法27颗离体上中切牙截冠根充后随机分为3组,分别采用一体化玻璃纤维桩核、预成纤维桩和铸造金合金桩核加铸造金属冠进行修复。使用万能力学试验机测试样本的抗折力并观察损坏模式。结果一体化玻璃纤维桩核组的抗折力为246.9±43.8N,显著高于预成玻璃纤维桩组（174.89±37.5N）,而与铸造金合金桩核组（290.1±84.2N）无显著差异。各组样本的损坏模式主要为牙颈部的损伤。结论CAD/CAM一体化玻璃纤维桩核修复上中切牙的抗折力与铸造金合金桩核近似,高于预成玻璃纤维桩。     

不同桩核系统修复上颌前磨牙双根管的抗折力研究

目的 比较不同桩核系统修复上颌前磨牙双根管的抗折强度.方法 将36颗因正畸拔除的上颌第一前磨牙,沿釉牙本质界冠方2mm水平切除牙冠,常规根管治疗后随机分为A、B、C三组,A组给予铸造镍铬合金桩核+金属全冠;B组给予MACROLOCKT石英纤维桩+树脂核+金属全冠,C组给予TENAX玻璃纤维桩+树脂核+金属全冠修复.应用力学试验机进行抗力性检测,记录试件破坏时施力的大小,观察试件破坏的形式及部位.结果 A组、B组、C组的离体牙桩核冠修复后牙体折断时的最大载荷分别为(1059.11±123.54)N、(1075.17±64.37)N、(1341.81 ±128.11)N.三组抗折强度两两比较,没有显著性差异(P＞0.05).A组不可复性折断明显多于B组和C组,差异有统计学意义(P＜0.05),B组与C组的抗折强度、破坏性折断例数比较,差异无统计学意义(P＞0.05).结论 采用不同桩核系统修复上颌前磨牙双根管的抗折强度无明显差异.玻璃纤维桩与石英纤维桩极大降低了根折率,有利于此类根管的保留和再修复.     

不同桩核金属烤瓷全冠修复后前牙抗剪切力的实验研究

目的 探讨不同桩核系统金属烤瓷全冠修复上颌前牙后修复体抗剪切力的差异.方法 对40颗大小相似的新鲜上颌中切牙行根管充填后截冠,随机分成4组,每组10颗.其中3组分别用纤维增强树脂桩和树脂核、预成钛合金桩和树脂核,铸造镍铬合金桩核修复,桩核与金属烤瓷全冠均用树脂粘接剂粘固;另1组用玻璃离子粘固剂粘固铸造镍铬合金桩核和金属烤瓷全冠作为对照组.经温度循环疲劳实验,用万能力学实验机测试样本牙的抗剪切力,并观测折裂型,进行统计学分析.结果 纤维增强树脂桩组、预成钛合金桩组、铸造桩核组及对照组的抗剪切力分别为(534.4±145.7)N、(499.8±168.9)N、(412.6±99.3)N、(337.4±121.2)N.纤维增强树脂桩组和预成钛合金桩组的抗剪切力大于对照组,差异有统计学意义(P＜0.05);纤维增强树脂桩组中可再修复折裂型样本牙数量多于其他组,差异有统计学意义(P＜0.05).结论 纤维增强树脂桩核金属烤瓷全冠修复有较好的抗剪切力,且折裂型多为可再修复型,修复后残根保存率高.     

玻璃纤维桩树脂核和钴铬合金铸造桩核修复上颌前牙抗折性能的临床评价

目的 评价玻璃纤维桩树脂核和钴铬合金铸造桩核修复上颌前牙的抗折性能。方法 收集临床上颌前牙牙体缺损患者25 例,326颗患牙,随机分为A、B两组,A组采用玻璃纤维桩树脂核修复,B组采用钴铬合金铸造桩核修复,并按中切牙、侧切牙和尖牙进行分层。观察1~2年内出现上颌前牙牙体折裂和桩折的情况。结果 在不同牙位的三组间,这两种修复方式的牙体折裂和桩折率差异具有统计学意义;在牙体缺损程度不同的两组间,这两种修复方式的牙体折裂和桩折率差异具有统计学意义。结论 采用玻璃纤维桩树脂核修复上颌前牙的抗折性能明显优于钴铬合金铸造桩核。     

不同修复方法对邻[牙合]缺损的下颌前磨牙根管治疗术后抗折性能影响的研究

目的：比较不同修复方法对邻[牙合]缺损的下颌前磨牙根管治疗术后抗折强度的影响。方法：将50颗离体下颌前磨牙随机分为A、B、C、D、E五组,每组10颗。A组（对照组）：完整离体牙,不做任何处理。其它四组（实验组）样本牙经根管治疗并制备邻骀缺损。B组：光固化树脂直接充填;C组：树脂充填＋铸造全冠修复;D组：铸造桩核＋铸造全冠修复;E组：纤维桩树脂核＋铸造全冠修复。所有样本牙在电子万能试验机上以与牙体长轴成30°角、lmm／min速度加载直至样本折裂,记录样本折裂时的载荷数值与折裂模式,对数据进行统计分析。结果：A、B、C、D、E组的折裂载荷分别为（952．93±102．03）、（383．97±46．31）、（733．51±54．94）、（604．76±123．73）和（893．44±87．08）N。五组之间两两比较,只有A、E两组之间差异无统计学意义,其余差异均有统计学意义;A、B、C、D、E组产生不可修复性折裂（根折位于包埋树脂平面以下）的样本数分别为0、2、1、9、3,其中D组牙体的折裂模式与其它三组差异均存在统计学意义,剩余三组间两两比较差异无统计学意义。结论：纤维桩树脂核联合全冠修复可作为邻[牙合]缺损的前磨牙根管治疗术后的优选修复方式。     

粘固剂对桩核烤瓷全冠修复后抗折强度的影响

目的探讨树脂粘结系统对前牙桩核烤瓷全冠抗折强度是否具有增强作用。方法40个新鲜拔除大小一致的上颌中切牙,随机分成4组,每组10个,分别用钛合金预成桩和铸造桩核修复,同一种桩及烤瓷全冠分别用树脂粘结系统和玻璃离子粘固剂粘固。经温度循环疲劳试验,用万能力学试验机,测试抗折强度,并观测折裂型。结果钛合金预成桩树脂粘结组抗折强度为499.82±168.90N,玻璃离子粘固剂组为388.98±125.22N;铸造桩核树脂粘结组抗折强度为412.55±99.29N,玻璃离子粘固剂组为337.41±121.18N。可再修复折裂型标本比例分别为40%、20%和20%、30%。统计学分析表明,两种桩核冠修复树脂粘结组的抗折强度及可再修复折裂型标本比例与玻璃离子粘固剂组均无显著性差异(P>0.05)。结论树脂粘结系统对金属桩烤瓷全冠修复的前牙抗折强度无显著的增强作用,有待进一步研究。     

The effect of post-core and ferrule on the fracture resistance of endodontically treated maxillary central incisors.

AIM: To evaluate the effect of post reinforcement, post type and ferrule on the fracture resistance of endodontically treated maxillary central incisors. MATERIALS AND METHODS: Sixty central incisor teeth were selected and grouped into six groups, viz. A, B, C, D, E, and F, each consisting of 10 specimens. Group A specimens were not subjected to any restorative treatment. Group B specimens were endodontically treated and crowned. Specimens of groups C and D were restored with custom cast post and core. Specimens of groups E and F were treated with prefabricated titanium post and composite core. Specimens of groups C and E were restored with porcelain-fused metal (PFM) crown having 2 mm ferrule. Specimens of groups D and F were restored with PFM crown having no ferrule. All the specimens were subjected to load (newton, N) on the lingual surface at a 135 degree angle to the long axis with a universal testing machine until it fractured. The fracture load and mode of fracture of each specimen were noted. One-way analysis of variance with Tukey honestly significant difference procedure was employed to identify the significant difference among the groups at 5% level (P < 0.05). RESULTS: There were significant differences among the six groups studied (P < 0.0001). The highest fracture strength was recorded with specimen of group C (1376.7 N). There were significant differences between groups A and D versus groups B, E, and F. There were no significant differences between groups B, E, and F. Cervical root fracture was the predominant mode of failure in all the groups except group A. CONCLUSION: The results showed that endodontically treated teeth restored with custom cast post core were as strong as the untreated group. Teeth restored with custom cast post core were better resistant to fracture than teeth restored with prefabricated titanium post and composite core. Ferrule is more important in custom cast post core than in prefabricated post and composite core.     

Survival rate and fracture strength of endodontically treated maxillary incisors with moderate defects restored with different post-and-core systems: an in vitro study

PURPOSE: This study compares the survival rate and fracture strength of endodontically treated maxillary incisors with moderate coronal defects restored with different post-and-core systems after exposure to an artificial mouth. MATERIALS AND METHODS: Sixty-four caries-free human maxillary central incisors were selected for standardized size and quality, endodontically treated, and decoronated 2 mm coronal to the cementoenamel junction. Group 1 was restored with titanium posts and composite cores, group 2 received zirconia posts and a composite core, and in group 3 zirconia posts with a heat-pressed ceramic core were used. Teeth restored with cast posts and cores served as controls. All teeth were prepared and restored with complete cast crowns. All samples were exposed to 1.2 million cycles in a computer-controlled chewing simulator with simultaneous thermocycling. In addition, the samples were loaded until fracture in a static testing device. RESULTS: The survival rates of the different groups were: 94% for titanium/composite, 63% for zirconia/composite, 100% for the all-ceramic post and core, and 94% for the cast post and core. The following mean fracture strengths were obtained: titanium/composite = 425 +/- 155 N, zirconia/composite = 202 +/- 212 N, zirconia/ceramic = 378 +/- 64 N, cast post and core = 426 +/- 178 N. The lower fracture load in the group with zirconia posts and composite cores was statistically significant. The use of zirconia posts resulted in fewer oblique root fractures. CONCLUSION: Prefabricated titanium posts with composite cores, zirconia posts with heat-pressed ceramic cores, and cast posts and cores yield comparable survival rates and fracture strengths for the restoration of crowned maxillary incisors with moderate coronal defects. Survival rates and fracture strengths for zirconia posts with composite cores are significantly lower, so this combination cannot be recommended for clinical use.     

Fracture strength and survival rate of endodontically treated maxillary incisors with approximal cavities after restoration with different post and core systems: an in-vitro study

OBJECTIVES: This study compared the fracture strength and survival rate of endodontically treated crowned maxillary incisors with approximal class III cavities and different core build-ups. METHODS: Sixty-four caries free human maxillary central incisors were selected for standardized size and quality, endodontically treated and prepared with approximal cavities 3mm in diameter. Group 1 was restored with titanium posts, group 2 received zirconia posts, in group 3 the root canal was partially filled with a hybrid composite. In the control group, only the access opening was restored. All teeth were prepared for and restored with full cast metal alloy crowns and subsequently exposed to 1.2 million cycles in a computer-controlled chewing simulator with simultaneous thermocycling. In addition, the samples were loaded until fracture in a static testing device. RESULTS: One specimen with composite reinforced root canal did not survive the dynamic load test. The following median fracture strengths in Newtons for the different groups were: titanium post 1038, zirconia 1057, composite resin 750, control (no post) 1171. The fracture load in group 3 (composite resin) was significantly lower (P<0.05) than in the other groups. CONCLUSIONS: The reconstruction of endodontically treated single rooted teeth with approximal cavities can be successfully performed by closure of the endodontic and additional cavities with composite. Cementation of endodontic posts offers comparable but no advantageous fracture resistance. Enlargement of the root canal space after completion of endodontic treatment should be avoided and cannot be compensated for by injection of composite resin. Less catastrophic failures were observed without post reconstruction.     

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.     

牙本质肩领的应用对不同桩核修复后修复体抗折性能的影响

目的：比较不同桩核系统及不同的牙体预备方法对残根抗折强度的影响。方法：40颗下颌前磨牙在釉牙骨质界处截冠后随机均分为四组。A组：金属桩修复的无肩领组。B组：金属桩修复的有肩领组。C组：纤维桩树脂核修复的无肩领组。D组：纤维桩树脂核修复的有肩领组。每组样本都采用金属全冠修复。实验标本包埋于树脂块中,在电子万能测力机上以1mm/min的速度加载直至断裂。结果：A组的抗折裂载荷最高,为3.0369±0.3388KN;D组的抗折强度最低,为2.0188±0.3864KN,A-C、A-B、C-D组间差异有显著性（P〈0.05）。可修复性断裂多见于纤维桩树脂核修复组,而不可修复性的破坏多见于铸造桩核组（P〈0.05）。结论：当牙体大部分缺损达釉牙骨质界时,通过冠延长术勉强预备牙本质肩领可显著降低桩核修复后牙根的抗折强度。而如不制备牙本质肩领,传统的金属桩核比纤维桩树脂核能承受更大的咀嚼力量。