Super-Band粘接剂降低银汞合金充填体微渗漏作用的研究

目的 :研究粘接剂对降低银汞合金充填体微渗漏的作用 ,以评价其在充填治疗中的意义 ,探讨减少银汞合金充填体边缘微渗漏的有效方法。方法 :选择无龋的离体牙 30颗 ,制备相同的洞型 ,随机分成实验组和对照组。实验组在牙洞各壁先涂上Super Band粘接剂后再用银汞合金充填 ,对照组不涂粘接剂而直接用银汞合金充填。用染色渗入法比较两组间的微渗漏情况。结果 :实验组银汞合金充填体的边缘微渗漏明显低于对照组 (P<0 .0 1 )。结论 :Super-Band粘接剂能够明显降低银汞合金充填体的微渗漏     

An evaluation of microleakage of various glass ionomer based restorative materials in deciduous and permanent teeth: An in vitro study

AimTo evaluate the microleakage of recently available glass ionomer based restorative materials (GC Fuji IX GP, GC Fuji VII, and Dyract) and compare their microleakage with the previously existing glass ionomer restorative materials (GC Fuji II LC) in primary and permanent teeth.MethodOne hundred and fifty (75 + 75) non-carious deciduous and permanent teeth were restored with glass ionomer based restorative materials after making class I cavities. Samples were subjected to thermocycling after storing in distilled water for 24 h. Two coats of nail polish were applied 1 mm short of restorative margins and samples sectioned buccolingually after storing in methylene blue dye for 24 h. Microleakage was assessed using stereomicroscope.ResultSignificant differences (P < 0.05) were found when inter group comparisons were done. Except when GC Fuji VII (Group III) was compared with GC Fuji II LC (Group II) and Dyract (Group IV), non-significant differences (P > 0.05) were observed. It was found that there was no statistically significant difference when the means of microleakage of primary teeth were compared with those of permanent teeth.ConclusionsGC Fuji IX GP showed maximum microleakage and GC Fuji VII showed least microleakage.     

An In Vitro Evaluation of the Microleakage under Complete Metal Crowns Using Three Adhesive Luting Cements

Despite the material advancements and precise laboratory techniques, cement lines are inevitable in fixed prosthodontics which leads to increased dependence on the integrity of the cement to maintain the marginal seal. The material class of luting agent is known to influence microleakage. Studies of cement dissolution and disintegration have produced varying results. Hence, this study was done to evaluate marginal leakage under complete metal crowns using three adhesive cements, two resin cements (one self cure, one dual cure) and a glass ionomer cement. Metal crowns were prepared on sixty intact extracted premolars and were randomly divided into three groups of twenty each, with each group using a different cement for luting. All the samples were then subjected to thermocycling and were sectioned using a diamond saw. Reflected Binocular Stereomicroscope at 100× magnification was used to study the extent of microleakage at both metal cement (MC) and tooth cement (TC) interface, at two opposite margins of each sectioned specimen. Data was analyzed with a one way analysis of variance. For comparison among the groups multiple comparison Bonferroni test was done. Within group data was analysed with independent student t test. Between three groups, metal crowns cemented with multilink cement showed significantly less microleakage at both the interfaces. Glass ionomer cement recorded maximum combined microleakage amongst three cements irrespective of the interfaces. Within group, glass ionomer and multilink cement showed more microleakage at MC interfaces than at TC interface. A complex interaction between variables related to dental restoration, luting agent and tooth structure probably influence microleakage. In vitro studies must always be followed by in vivo studies before definite conclusion can be drawn.     

漂白处理对树脂充填体边缘微渗漏的影响

目的:评价35%过氧化氢凝胶对树脂充填体边缘微渗漏的影响。方法:选择离体上颌第三磨牙40颗,在颊面制备Ⅴ类洞复合树脂分层充填,光照固化抛光后按处理时间随机分为4组(n=10):A(对照组)、B(10 min)、C(20 min)、D(30min)。将凝胶涂布于充填体表面进行漂白处理后冷热循环500次,再用2%亚甲蓝溶液染色24 h,沿颊舌纵向剖开,体式显微镜观察并记录染料渗入深度。用Kruskal-Wallis法进行数据分析;Mann-Whitney法组间两两比较,检验水准均为α=0.05。结果:不同漂白处理时间对树脂充填体边缘微渗漏的影响有统计学意义(P<0.05);组间比较显示A与C、A与D、B与D、C与D间差异有统计学意义。结论:35%过氧化氢凝胶漂白处理使复合树脂充填体的边缘微渗漏程度增加。     

两种技术充填后根管桩腔预备后体外微渗漏研究

目的：研究桩腔预备对两种根管充填方法根管封闭效果的影响。方法：选择近期拔除的40颗单根管离体牙,采用逐步后退法机用扩管预备,随机分为A、B、C、D4组,配合AH—plus糊剂分别采用牙胶尖侧方加压（A、B组）及热牙胶垂直加压充填根管（C、D组）,1周后对A、C组作桩腔预备,B、D两组作对照,印度墨水染色,对染料渗透的长度进行测量及分析。结果：B组和D组根尖微渗漏值无统计学差异,A组和B组、A组和C组、C组和D组的染料渗透长度有显著性差异（P〈0．01）。结论：桩腔预备降低了根尖封闭效果,热牙胶垂直加压充填对微渗漏的影响小于牙胶尖侧方加压充填。     

有无洞缘斜面对聚合瓷嵌体微渗漏影响的实验研究

目的评估洞缘斜面对聚合瓷嵌体直接修复的边缘微渗漏的影响。方法 60颗人磨牙随机分成2组,每组30颗,在每颗牙的近中HE面制备典型的Ⅱ类洞,一种制备短斜面,一种不制备短斜面,聚合瓷嵌体直接修复经硝酸银染色后,每颗牙沿近远中方向经修复体切为3部分,取中间部分为观察对象。结果聚合瓷嵌体直接修复在HE面的微渗漏有明显差异（P〉0.05）。结论斜面组的微渗漏现象要比不做斜面的少,但是在HE面无明显差异（P〉0.05）,在龈壁则有显著差异（P〈0.05）。     

渗透性树脂对树脂修复体微渗漏影响的实验观察

目的:观察使用渗透性树脂ICON对修复体边缘进行处理后的微渗漏变化。方法:20颗健康离体牙随机分为2组,颊面制备深度2mm的窝洞,Z350树脂充填,A组使用渗透性树脂ICON处理树脂修复体边缘处的牙体组织及树脂牙体结合处,B组为对照组。37℃水浴条件下分别置于0.1%罗丹明B荧光染料浸染,24h后激光扫描共聚焦显微镜测量染液渗入深度,定量评价微渗漏程度,对检测结果进行统计学分析。结果:A、B组微渗漏差异有统计学意义(P<0.05)。结论:渗透性树脂对改善树脂修复体微渗漏状况有明显效果。     

Vertical discrepancy and microleakage of laser-sintered and vacuum-cast implant-supported structures luted with different cement types

Objectives

This study aimed to evaluate the vertical misfit and microleakage of laser-sintered and vacuum-cast cement-retained implant-supported frameworks.

Methods

Three-unit implant-fixed structures were constructed with: (1) laser-sintered Co–Cr (LS); (2) vacuum-cast Co–Cr (CC); and (3) vacuum-cast Pd–Au (CP). Every framework was luted onto 2 prefabricated abutments under constant seating pressure. Each alloy group was randomly divided into three subgroups (n = 10) according to the cement used: (1) Ketac Cem Plus (KC); (2) Panavia F 2.0 (PF); and (3) RelyX Unicem 2 Automix (RXU). After 30 days of water ageing, vertical discrepancy was measured by SEM, and marginal microleakage was scored using a digital microscope. Three-way ANOVA and Student–Newman–Keuls tests were run to investigate the effect of alloy/fabrication technique, FDP retainer, and cement type on vertical misfit. Data for marginal microleakage were analysed with Kruskal–Wallis and Dunn's tests (α = 0.05).

Results

Vertical discrepancy was affected by alloy/manufacturing technique and cement type (p < 0.001). Despite the luting agent, LS structures showed the best marginal adaptation, followed by CP, and CC. Within each alloy group, KC provided the best fit, whilst the use of PF or RXU resulted in no significant differences. Regardless of the framework alloy, KC exhibited the highest microleakage scores, whilst PF and RXU showed values that were comparable to each other.

Conclusions

Laser-sintered Co–Cr structures achieved the best fit in the study. Notwithstanding the framework alloy, resin-modified glass-ionomer demonstrated better marginal fit but greater microleakage than did MDP-based and self-adhesive dual-cure resin cements. All groups were within the clinically acceptable misfit range.

Clinical significance

Laser-sintered Co–Cr may be an alternative to cast base metal and noble alloys to obtain passive-fitting structures. Despite showing higher discrepancies, resin cements displayed lower microleakage than resin-modified glass-ionomer. Further research is necessary to determine whether low microleakage scores may guarantee a suitable seal that could compensate for misfit.     

Assessment of laminate technique using glass ionomer and resin composite for restoration of root filled teeth

Objective

To evaluate the open laminate technique using glass ionomer cements (GIC) in association with a low shrink composite for restoring root filled premolars.

Methods

Extensive MOD cavities plus endodontic access and root filling were performed in intact extracted maxillary premolars. Three restoration types were evaluated: (1) resin composite alone; (2) resin-modified GIC (RM-GIC) open laminate plus resin composite; (3) conventional GIC open laminate plus resin composite (n = 8 for all groups and tests). Three tests were conducted to assess restorations: (A) inward cusp deflection during light curing, using DCDTs; (B) fracture strength using a ramped oblique load at 45° to the long axis in a servohydraulic testing machine in comparison with intact and unrestored teeth; (C) proximal marginal leakage using methylene blue dye and the effect of thermocycling. Data were analysed using 1-way ANOVA for cuspal deflection and fracture strength and Fisher's exact test for leakage.

Results

Laminate restorations resulted in significantly less cuspal deflection compared with resin composite (4.2 ± 1.2 μm for RM-GIC and 5.1 ± 2.3 μm for conventional GIC vs. 12.2 ± 2.6 μm for composite, P < 0.001). Fracture strength was not significantly different among all groups. Failure with all restorations was predominantly adhesive at the tooth-restoration interface. The two laminate groups showed significantly better marginal seal than composite alone, but sealing ability of conventional GIC deteriorated after thermocycling.

Conclusions

Laminate restoration of root filled teeth had beneficial effects in terms of reducing cuspal deflection and marginal seal, with acceptable fracture strength.     

Effect of operator skill in relation to microleakage of total-etch and self-etch bonding systems

OBJECTIVES: To evaluate the influence of operator skill on microleakage in class V restorations using two-step bonding systems. METHODS: Two standardized box cavities were made on the buccal and lingual surfaces of 54 human bicuspid teeth, with the cervical margin in dentin. The teeth were randomly assigned to two groups according to the operator's skill. Students group: undergraduate students. Expert group: a dentist with 20 years of clinical experience in dental adhesion. The buccal cavities of each tooth were treated with Prime&Bond NT (two-step total-etch system); the lingual cavities were treated with AdheSE (two-step self-etch system). All cavities were restored by a single calibrated operator with one bulk increment of resin composite (InTens; Ivoclar Vivadent). Specimens were thermocycled, immersed in 2% methylene blue and sectioned in a bucco-lingual plane in the middle of the restorations. They were then examined under a stereomicroscope and scored according to microleakage by two operators who were blind to the specimen preparation. The data was subjected to a multilevel statistical model. RESULTS: The microleakage resulting from the self-etch adhesive was similar in the student and in the expert groups. On the other hand, the total-etch adhesive microleakage within the expert group resulted lower than that within the student group. However, the interaction term skill x adhesive resulted statistically significant at the dentin margin (p=0.0474) but not at the enamel margin (p=0.1267). CONCLUSION: While the total-etch adhesive used in this study showed to be skill-sensitive, the self-etch one proved to be less skill-sensitive in obtaining a reliable seal with dentin.