应用纤维桩改进式根管充填对根尖微渗漏的影响

目的：通过离体牙试验,探讨高强度玻璃纤维增强树脂复合材料（FRC）桩钉改进式根管充填对根尖微渗漏的影响。方法：选60例离体前牙,采用碘仿氧化锌糊剂及牙胶尖做侧压充填,然后实验组在已充填的根管内加压插入FRC桩,对照组不再做处理,对两组做根尖染色渗漏试验。结果：实验组根尖微渗漏较对照组小,两者比较,差异有统计学意义。结论：常规根管充填后,采用FRC桩加固充实根管,能提高根充的充实度,有效减少根充后根尖微渗漏的产生。     

几种银汞合金替代材料微渗漏的体外实验研究

目的了解几种银汞合金替代材料的密合性能,为选择后牙充填材料提供参考依据.方法将25个新鲜离体无龋前磨牙于颊舌面制备50个V类洞,数字表法随机分为5组.分别采用Glacier前/后牙复合树脂、Beautifil氟化玻璃聚合体、Hi-dense银粉加强型玻璃离子、Surefil高密度后牙树脂、银汞合金等五种材料充填.用1%亚甲基蓝染液进行渗透试验,观圹察染料渗透深度并进行分析.结果5种材料均有程度不等的微渗漏出现.其中银汞合金充填组渗漏率最大,与其他各组渗漏率比较,具有显著差异(P＜0.05).Glacier.和Beautiful与其余各组相比渗漏率最小,具有显著差异(P＜0.05).结论 4种银汞合金替代材料在抗微渗漏的特性方面Glacier和Beautiful最佳,Surefil.和Hi-dense次之,银汞合金较差.     

Impact of Dentin Substrate Modification with Chitosan-Hydroxyapatite Precursor Nanocomplexes on Sealer Penetration and Tensile Strength

IntroductionThe purpose of this study was to evaluate the effect of dentin conditioning with chitosan-hydroxyapatite precursor (C-HA) nanocomplexes on the depth of tricalcium silicate sealer penetration into dentinal tubules and ultimate tensile strength (UTS).Methodssurface charge and size distribution for C-HA nanocomplex formulation was evaluated followed by bioactivity assessment of standardized films of C-HA nanocomplexes (n = 15) incubated in simulated body fluid. Mineralization potential was assessed with X-ray diffraction and Fourier-transform infrared spectroscopy, whereas scanning electron microscopy was used for ultrastructural evaluation. Static water contact angles and UTS were measured on dentin discs (n = 2/group) and dentin beams (n = 10/group) treated with/without sodium hypochlorite/EDTA and C-HA nanocomplex conditioning. In phase 2, the depth of sealer penetration after C-HA nanocomplex conditioning was evaluated using fluorescent imaging (n = 12/group). The percent area penetration and mean/maximum penetration depth were calculated at 4- and 6-mm levels from the root apex. Data from contact angle measurements, mechanical testing, and penetration assessment parameters were subjected to the independent samples t test with a significance level set at P < .05.ResultsA formulation of C-HA nanocomplexes (2 mg/mL) was chosen as a polyanionic, hydrophilic, nonaggregating concentration having bioactivity potential established through the formation of phosphate/carbonate bonds and the crystalline nature of the formed minerals. A significantly lower contact angle and higher UTS were registered for the C-HA nanocomplex–conditioned group (P < .05). Statistically significant (P < .05) greater sealer penetration was recorded at the 4-mm level for all assessment parameters and percent area penetration at 6 mm for the C-HA nanocomplex group.ConclusionsC-HA nanocomplex conditioning enhances dentin surface wettability to facilitate greater tricalcium silicate sealer penetration and UTS of dentin.     

Microleakage of Different Self-Adhesive Materials for Lithium Disilicate CAD/CAM Crowns

Objectives: To evaluate the microleakage and marginal gap of various luting materials after cementing ceramic crowns. Methods: Cervical margins of human molars were designed as circular chamfers. Cementation of full-contour ceramic crowns was conducted with zinc-phosphate cement (Harvard cement), resin cement (Panavia F 2.0) and self-adhesive resin cements (RelyX Unicem, BifixSE, MaxCem Elite, PermaCem2.0, G-Cem). Aging of specimens was performed in artificial saliva, at 37 °C for four weeks and thermocycling. The marginal gap was measured with a scanning electron microscope and silver precipitation within the microleakage. All data were compared statistically. Results: Independent of the margin preparation, the highest median value for microleakage was 320.2 μm (Harvard cement), and the lowest was 0 μm (Panavia F 2.0). The median value for enamel was 0 µm and for dentin 270.9 μm (p < 0.001), which was independent of the luting material. The marginal and absolute marginal gaps were not significantly different between the tested materials. There was no correlation between microleakage and the marginal gaps. Conclusion: Significant differences in microleakage were found between the tested luting materials (p < 0.05). Independent from the luting materials, the microleakage in dentin showed significantly higher values than in enamel.     

Characterization of heat resistant hydraulic sealer for warm vertical obturation

ObjectiveWarm vertical compaction of gutta-percha is a technique that is used by most specialists for root canal obturation. The sealers currently available exhibit irriversible chemical changes when heated. New biologically active sealers that do not sustain irreversible changes when heated are an attractive alternative to be used with warm vertical compaction obturation technique. The aim of this study was to measure the heat generated by warm vertical compactors inside the root canal, characterize a newly developed root canal sealer at different temperatures and verify its suitability at the actual temperature window used clinically.MethodsThe typical temperatures generated by two heat carriers in a root canal were assessed by thermocouples. Two premixed root canal sealers TotalFill BC and HiFlow BC (FKG, Switzerland) were allowed to set and they were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction analysis (XRD) immediately after setting and by XRD after 28 days in physiological solution. The ion leaching in solution was assessed by inductively coupled plasma (ICP). The organic component was extracted in acetone and assessed by Fourier transform infrared spectroscopy (FT-IR) for both the unset sealer and sealer subjected to different temperatures. The heat profiles of both sealers were investigated by FT-IR and thermographic analysis.ResultsNone of the devices tested achieved the temperatures set on the dial. The highest temperatures were coronal followed by apical for both devices. The sealers were identical except for the vehicle. The inorganic components included tricalcium silicate, dicalcium silicate and zirconium oxide. No calcium hydroxide was produced by any of the sealers after immersion in physiological solution but calcium was released in solution. The chemistry of both sealers was modified when heated but both recovered when cooled.SignificanceThe heat carriers were unreliable and the heat generated inside the canal was not the same as the temperature set on the dial. Since both sealers had identical chemistry save for minimal modifications to the organic component and were both resistant to heat, TotalFill BC sealer is recommended for use with warm vertical compaction technique as it is cheaper and as effective as the HiFlow.     

The effect of root canal preparation on microleakage within endodontically treated teeth: an in vitro study

AIM: The purpose of this study was to evaluate the effects of smear layer and canal instrumentation on leakage in root-filled teeth. METHODOLOGY: Six groups (n = 12) of freshly extracted human canines and premolars with closed apices and single roots were used. Groups A, B, C, and D were instrumented with engine-driven rotary nickel-titanium MCXIM files and Groups E and F were instrumented with conventional stainless steel hand files. Groups A, C, and E were flushed with 3.0 mL of 17.0% REDTA to remove the smear layer prior to obturation. All teeth were flushed with 5.25% NaOCl, then obturated with AH-26 sealer and either the lateral condensation (Groups C-E) or thermomechanical compaction technique (Groups A and B). Copper wire was placed coronally in contact with the gutta-percha in each tooth and, after immersion in 0.9% NaCl solution, a 10 volt dc voltage was connected between each tooth and a stainless steel electrode. The current flow in the circuit was observed for 45 days. One way ANOVA and Duncan's Multiple Range Test were used to compare Groups A-F at time intervals of 10, 20, 30 and 45 days and identify statistically significant differences. RESULTS: Significantly less microleakage occurred when the smear layer was removed and when the canals were obturated with thermoplasticized gutta-percha. Canals instrumented with engine-driven NiTi files exhibited less leakage than hand-instrumented canals irrespective of obturation method. CONCLUSIONS: Smear layer removal is beneficial to root canal sealing. Obturation with thermoplasticized gutta-percha provides a superior seal whilst canal instrumentation with engine-driven NiTi files reduces the extent of microleakage in root canals.     

银汞合金充填应用树脂粘结剂的作用研究

目的：研究银汞合金充填时应用树脂粘结剂的作用。方法：进行染料渗透试验和扫描电镜观察。结果：使用粘结剂组染料渗漏的例数少、程度轻，差异性非常显著；扫描电镜可见粘结剂与洞壁和银汞合金均有较好粘结，密合度好。结论：银汞合金充填应用树脂粘结剂可以明显减少微渗漏和增加洞壁密合度。     

四种光固化复合树脂修复物边缘微渗漏的体外试验研究

目的:比较4种光固化充填材料修复体边缘微渗漏.方法:在新鲜拔除的40个人前磨牙的颊侧牙颈部制洞,将牙齿分为4组,每组10个.分别充填4种修复材料Restorative Z-350、Z-100(3M),Chafisma(Dentsply),Durafill(Kulzer)经冷热交替试验(4～60℃,循环600次),采用10 g/L碱性品红染料渗入法,在体视显微镜下观察修复体与牙体洞壁间边缘微渗漏.结果:4种材料中3M-Z350微渗漏最小,Durafill最大,DurafiU与其他3组相比有显著性差异(P＜0.05);3M-Z100和Chrisma无显著性差异(P＞0.05);3MZ350与其他3组相比有显著性差异(P＜0.01).结论:3M-Z350可能是临床修复牙体缺损的较好材料.     

比较自酸蚀和全酸蚀黏结剂对树脂微渗漏的影响

目的:比较自酸蚀和全酸蚀黏结剂对复合树脂微渗漏的影响。方法:在新鲜拔除的24个磨牙面制备面洞,随机分为2组,分别应用3M Adper Prompt自酸蚀黏结剂和3M Adper Single Bond2全酸蚀黏结剂,进行3MZ250树脂充填。经温度循环后,品红溶液染色,在体视显微镜下对牙齿颊舌向切片,观察修复体边缘染料渗漏情况。结果:整体微渗漏(包括釉质-牙本质),两种黏结剂之间无显著性差异(P>0.05);但是釉质微渗漏,自酸蚀组大于全酸蚀组,其差异有统计学意义(P<0.05)。结论:自酸蚀黏结剂对釉质的黏结弱于全酸蚀黏结剂。     

Cuspal deflection and microleakage in premolar teeth restored with resin-based composites with and without an intermediary flowable layer

OBJECTIVES: To assess cuspal deflection and cervical enamel microleakage with and without an intermediary flowable RBC layer for the incremental restoration of mesio-occluso-distal (MOD) cavities with two resin-based composites (RBCs). METHODS: Forty sound upper premolar teeth had standardised MOD cavities prepared. Restoration of the teeth involved the placement of the RBCs (Filtek P60 or Filtek Supreme) in eight increments with the appropriate bonding system with and without an intermediary flowable RBC layer (Filtek Flow). Buccal and palatal cusp deflections were recorded post-irradiation using a twin channel deflection measuring gauge. Following restoration, the teeth were thermocycled, immersed in a 0.2% basic fuchsin dye for 24h, sagittally sectioned and examined for cervical enamel microleakage. RESULTS: A significant reduction in cuspal deflection was evident when both RBC materials were used to restore the cavity by employing an intermediary flowable (P<0.001) compared with when no intermediary flowable was utilised. No statistically significant differences were identified in microleakage between the teeth restored with Filtek P60 or Filtek Supreme when an intermediary flowable (Filtek Flow) was employed. CONCLUSIONS: The results of the current study suggest that there was a benefit to the operator in terms of a reduction in cuspal deflection but not from the maintenance of the synergism of the adhesive bond, namely microleakage at the cervical enamel cavosurface margin, when an intermediate layer of a flowable RBC was used under higher elastic modulus RBCs.