模拟正畸牵引术联合肩领设计对残根抗折力的影响

目的 探讨不同高度的牙本质肩领设计对预成碳纤维桩核修复后牙体抗折力的影响.方法 24颗完整、离体、单根管下颌第一前磨牙于颊侧釉牙骨质界上1.0 mm处截冠,经根管治疗后制备残根模型.通过模拟正畸牵引术(牙合)向牵引残根并在残根颈部预备一定高度的牙本质肩领;按预备的牙本质肩领高度不同(0.0、1.0、2.0 mm)依次分为A、B、C三组,预成碳纤维桩核联合铸造全冠修复残根.试件自全冠颈缘完成线下2.0 mm包埋于自凝塑料内,电子万能试验机以与牙长轴成150°、横梁位移速度1.0 mm/min于颊尖顶加载,测定折裂载荷并进行统计分析.结果 三组试件的折裂载荷(kN)均值依次为(1.13±0.15)、( 1.63±0.14)、(1.92±0.19).预备牙本质肩领可显著提高牙体的折裂载荷(F=48.437,P＜0.001);并且随着预备的牙本质肩领高度增加,牙体的折裂载荷显著增大(P＜0.05).结论 在残根颈部设计牙本质肩领,可明显提高牙体的折裂载荷.     

Comparative evaluation of effects of different surface treatment methods on bond strength between fiber post and composite core

PURPOSE

Debonding of a composite resin core of the fiber post often occurs at the interface between these two materials. The aim of this study was to evaluate the effects of different surface treatment methods on bond strength between fiber posts and composite core.

MATERIALS AND METHODS

Sixty-four fiber posts were picked in two groups (Hetco and Exacto). Each group was further divided into four subgroups using different surface treatments: 1) silanization; 2) sandblasting; 3) Treatment with 24% H₂O₂, and 4) no treatment (control group). A cylindrical plexiglass matrix was placed around the post and filled with the core resin composite. Specimens were stored in 5000 thermal cycles between 5℃ and 55℃. Tensile bond strength (TBS) test and evaluation using stereomicroscope were performed on the specimen and the data were analyzed using two-way ANOVA, Post Hoc Scheffe tests and Fisher''s Exact Test (α=.05).

RESULTS

There was a significant difference between the effect of different surface treatments on TBS (P<.001) but different brands of post (P=.743) and interaction between the brand of post and surface treatment (P=.922) had no significant effect on TBS. Both silanization and sandblasting improved the bonding strength of fiber posts to composite resin core, but there were not any significant differences between these groups and control group.

CONCLUSION

There was not any significant difference between two brands of fiber posts that had been used in this study. Although silanization and sandblasting can improve the TBS, there was not any significant differences between surface treatments used.     

Influence of remaining coronal structure and of the marginal design on the fracture strength of roots restored with cast post and core

Abstract

Objective. The purpose of this study was to evaluate the fracture strength of roots that were prosthetically restored with cast post and core with or without any remaining coronal structure and with different finish lines. Materials and methods. Sixty bovine incisors were sectioned below the cementoenamel junction, endodontically treated and randomly divided into six experimental groups (n = 10) containing teeth with or without any remaining coronal structure and with a beveled shoulder, a chanfered or a shoulder finish line design. The cast post and core were luted with dual-cured resin cement. The metal crowns were cemented with zinc phosphate cement. The specimens were subjected to a tangential compressive load (135° angle) at a crosshead speed of 0.5 mm/min until failure, using a universal testing machine. The fracture strength data were analyzed using the ANOVA and LSMeans (least square means) tests (α = 0.05). Results. The data indicated that the teeth with 2 mm of remaining coronal structure showed the highest fracture strength values when compared with the teeth without any remaining structure (p < 0.05). As to the different finish line designs, the highest fracture strength values were obtained for the beveled shoulder, followed by the chanfered and then by the shoulder designs (p < 0.05). Conclusions. It may be concluded that, to increase fracture strength, a beveled shoulder and 2 mm of remaining coronal structure are the ideal conditions.     

In Vitro Fracture Resistance of Endodontically Treated Roots Filled with a Bonded Filling Material or Different Types of Posts

AimThis study aimed to compare the fracture resistance of roots filled with a bonded material, fiber posts, or titanium post systems.MethodsCanals in the first group were filled with AH Plus and gutta-percha cones, and roots in the second group were filled with Epiphany sealer and Resilon cones. The root fillings (60 roots) were removed up to 4 mm from the canal apex to obtain 10-mm-deep post spaces, and posts were cemented. The groups were as follows: AH Plus control group, Epiphany control group, AH Plus fiber post group, AH Plus titanium post group, Epiphany fiber post group, and Epiphany titanium post group. Fracture tests were performed by using an Instron testing machine. The force was applied at a 45° axial angle with a constant speed of 1 mm/min. For each sample, the force at which fracture occurred was recorded in units of newtons. Statistical analysis was carried out by using analysis of variance test.ResultsThere was no statistically significant difference between all groups (P > .05).ConclusionsTitanium posts, fiber posts, and Epiphany root canal filling systems were found to have no reinforcing effect on endodontically treated roots.     

纤维桩和金属铸造桩修复疗效的回顾性比较

目的比较纤维桩和金属铸造桩在前牙和前磨牙残冠残根修复中的临床疗效。方法选择2009年至2010年我科门诊治疗中因残冠残根而行桩核冠修复的196例(262颗患牙)病例,以纤维桩作冠修复,门诊随访24个月,并与我科2007年至2008年211例(278颗患牙)对金属铸造桩作冠修复的研究结果作比较,观察两种桩核材料的临床疗效。结果经24个月的随访,纤维桩的成功率为95.42%,金属铸造桩的成功率为88.13%,两组之间的差异有统计学意义(P<0.05)。纤维桩的失败病例中均为冠折或桩核脱落。结论在前牙和前磨牙桩核冠修复中使用纤维桩的临床疗效优于金属铸造桩核,且纤维桩失败后可以进行二次修复,以达到保留患牙的目的。     

有限元法分析不同桩核材料对全瓷冠应力分布规律的影响

目的：探讨不同桩核材料对全瓷冠应力分布规律的影响,为临床修复设计提供依据。方法：利用螺旋CT断层图像,构建上颌第一磨牙舌侧1／2缺损桩核及全瓷冠修复的有限元分析模型,设计垂直集中载荷600N的加载方式,利用ANSYS软件分析全瓷冠的最大张应力和vonmises应力值。结果：全瓷冠的VOllraises应力和最大张应力均集中于载荷加载部位,并呈放射状向周围递减,vonnlises应力的集中区域向颊侧方向延伸。结论：桩核材料弹性模量不同对全瓷冠的应力分布影响较大,临床上应根据牙体缺损情况选择桩核材料。     

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。     

不同设计形式铸造桩核修复重度缺损磨牙三维有限元分析

目的 通过三维有限元方法分析不同根桩数目铸造桩核修复重度缺损上颌第一磨牙后牙体组织应力分布.方法 以右上颌第一磨牙为标本,通过CT扫描获得图像信息,采用Mimics三维建模软件、FreeForm视觉设计系统建立健康上颌第一磨牙、单根铸造桩核、双根铸造桩核以及三根铸造桩核修复重度缺损上颌第一磨牙的三维有限元模型;利用Ansys有限元软件分析比较加载后牙体组织的Von Mises应力、拉应力和压应力峰值分布和变化.结果 随着根桩数目从单根桩增加到双根桩和三根桩,牙本质的Von Mises应力峰值和压应力峰值呈减小趋势,而拉应力峰值增大并集中在与核有夹角的腭根桩和远中颊根桩末端对应的根管牙本质.桩核修复后的磨牙牙体组织应力峰值均比健康第一磨牙小.结论 铸造桩核修复重度缺损上颌第一磨牙时,根桩数目和桩与核的夹角均影响牙体组织应力分布.     

Degree of mucositis and duration of neutropenia are the major risk factors for early post-transplant febrile neutropenia and severe bacterial infections after reduced-intensity conditioning

Background and objectives: Whether the intensity of the conditioning regimen affects febrile neutropenia (FN) and severe bacterial infections (SBIs) is not well established. We analyzed the risk factors (RFs) for the development of FN and SBI in the first 100 d post‐transplant in 195 consecutive adult recipients of a reduced‐intensity conditioning allogeneic hematopoietic stem cell transplantation (RIC‐allo). Materials and methods: The RIC regimens consisted of fludarabine plus melphalan (62%) or busulphan (38%) (FluMel or FluBu). SBIs include pneumonia, urinary tract infections, and bacteremia. Results: FN occurred in 141 patients (72%), always in the first 30 d post‐allo‐RIC. However, a SBI occurred in only 27 patients (14%) during this early post‐transplant period (P < 0.02) and NCI CTC grade III–IV mucosal damage in the first 10 d post‐transplantation (P = 0.03). RFs identified to SBI by multivariate analysis included corticosteroid therapy before day +100 (P < 0.01), mycophenolate mofetil‐based graft‐versus‐host disease (GVHD) prophylaxis (P < 0.01), and previous SBI before day +30 (P < 0.01). The rate of SBI from day +30 to +100 varied according to the number of RFs; thus, the rate of SBI was 1% in patients without any RF, 17% in patients with one RF, 29% with one RFs, and 53% in those with all three RFs. Conclusions: After an RIC‐allo, FN and early SBI occurred mostly in patients with severe mucositis and early‐onset neutropenia, while postengraftment high‐dose steroid therapy for acute GVHD was the major RF.