In Vitro Bioactivity and Biocompatibility of Dicalcium Silicate Cements for Endodontic Use

IntroductionThe purpose of this study was to examine the in vitro bioactivity and biocompatibility of sol-gel–derived dicalcium silicate cements.MethodsThe morphology, phase composition, and compressive strength of the novel cement were investigated after immersion in a simulated body fluid for different periods of time. Cement biocompatibility was evaluated by incubating the cement specimens with MG63 human osteoblast-like cells.ResultsAfter immersion in a simulated body fluid as little as 1 hour, the cements were covered with clusters of bone-like apatite spherulites. The characteristic peaks of apatite at 2θ = 25.9 degrees and 31.8 ? 32.9 degrees appeared. The compressive strength of the cement was increased from the initial strength value of 12.3 MPa to 1-day strength value of 20.2 MPa; these values were significantly different (P < .05). The MG63 cell viability increased 15% and 23% on the cement surfaces when compared with the control on hour 6 and day 7 of incubation, respectively. The cells appeared flat and exhibited intact, well-defined morphology on the cement surface.ConclusionsBoth bioactivity and biocompatibility of the dicalcium silicate cement consistently make it a potential candidate for endodontic use.     

Cytotoxicity of a New Calcium Silicate Endodontic Sealer

Introduction

Resin sealers with biocompatible and bioactive additives have been used in clinical practice. Recently, a calcium silicate root canal sealer was introduced under the name BioRoot RCS (Septodont, Saint Maur-des-Fossés, France). The aim of this study was to evaluate the effects of BioRoot RCS on cell survival and proliferation of cultured cells in parallel with an epoxy resin sealer with calcium phosphate and calcium oxide and a salicylate resin sealer with mineral trioxide aggregate filler. The tested hypothesis was that BioRoot RCS is significantly less cytotoxic than the other tested sealers.

Evaluation of Cytotoxicity and Physicochemical Properties of Calcium Silicate-based Endodontic Sealer MTA Fillapex

IntroductionThe aim of the study was to evaluate the cytotoxicity, radiopacity, pH, and flow of a calcium silicate–based and an epoxy resin–based endodontic sealer, MTA Fillapex (Angelus, Londrina, PR, Brazil) and AH Plus (Dentsply, Konstanz, Germany), respectively.MethodsCytotoxicity, radiopacity, and flow evaluation were performed following ISO requirements. The pH level was measured at periods of 3, 24, 72, and 168 hours. Cytotoxicity was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay to check the Balb/c 3T3 cells viability at 1- to 4-week periods. Data were statistically analyzed by analysis of variance and the Tukey test with a significance level of 5%.ResultsIn all tested periods, MTA Fillapex was more cytotoxic than AH Plus (P < .05). Although AH Plus presented higher radiopacity than MTA Fillapex (P < .05), both sealers showed minimum required values. MTA Fillapex presented alkaline pH in all experimental times, whereas AH Plus cement showed a slightly neutral pH and a flow significantly lower than that of MTA Fillapex (P < .05).ConclusionsAlthough MTA Fillapex was more cytotoxic than AH Plus, it showed suitable physicochemical properties for an endodontic sealer.     

Marginal Gaps between 2 Calcium Silicate and Glass Ionomer Cements and Apical Root Dentin

Introduction

The outcome of periapical surgery has been directly improved with the introduction of novel material formulations. The aim of the study was to compare the retrograde obturation quality of the following materials: calcium silicate (Biodentine; Septodont, Saint-Maur-des-Fosses, France), mineral trioxide aggregate (MTA+; Cerkamed Company, Stalowa Wola, Poland), and glass ionomer cement (Fuji IX; GC Corporation, Tokyo, Japan).

In Vitro Biocompatibility and Oxidative Stress Profiles of Different Hydraulic Calcium Silicate Cements

Introduction

MTA Plus is a new calcium silicate cement with unknown cytotoxicity characteristics. The objectives of this study were to examine the effect of MTA Plus on the viability, apoptosis/necrosis profile, and oxidative stress levels of rat odontoblast-like cells.

Methods

MDPC-23 cells were exposed to gray and white MTA Plus (GMTAP, WMTAP), gray and white ProRoot MTA (GMTA, WMTA) cements, or their eluents. The cells were evaluated for (1) cell viability by using XTT assay, (2) apoptosis/necrosis by using flow cytometry and confocal laser scanning microscopy, and (3) oxidative stress by measuring reactive oxygen species.

Results

XTT assay showed that all test cements exhibited marked initial cytotoxicity that decreased with time. By the end of the third week, GMTAP and GMTA were comparable to untreated cells (negative control) in terms of cell viability, whereas WMTAP and WMTA were significantly lower than the untreated cells. Apoptosis/necrosis profiles of cells exposed to WMTAP and GMTAP were not significantly different from untreated cells, whereas cells exposed to WMTA and GMTA showed significantly less viable cells. All experimental groups exhibited reduction of intracellular reactive oxygen species formation compared with untreated cells, although cells exposed to WMTA were not significantly different from untreated cells.

Conclusions

Both the gray and white versions of MTA Plus possess negligible in vitro cytotoxic risks that are time and dilution dependent. They enrich the spectrum of hydraulic calcium silicate cements currently available to clinicians for endodontic applications.     

Tricalcium Silicate Cements with Resins and Alternative Radiopacifiers

Objective

The objectives of this study were the investigation of the setting mechanisms and characterization of radiopacified tricalcium silicate–based materials mixed with different liquid vehicles.

Methods

Tricalcium silicate cement replaced with 20% of either zirconium oxide or barium zirconate radiopacifier was investigated. The cements were mixed with water, an epoxy resin, or a light-cured Bis-GMA–based resin. The setting mechanism and characterization of set materials after immersion in Hank's balanced salt solution (HBSS) for 28 days were investigated by scanning electron microscopy of polished specimens and x-ray diffraction analysis. The bioactivity and surface microstructure of cements immersed in HBSS or water were also assessed by similar techniques together with leaching in solution investigated by inductively coupled plasma emission spectroscopy.

Results

The formation of calcium hydroxide as a by-product of cement reaction was affected by the type of radiopacifier and also by the resin vehicle used. Barium zirconate enhanced the formation of calcium hydroxide as indicated by both scanning electron microscopy and x-ray diffraction analysis. The use of resins as vehicles reduced the formation of calcium hydroxide, with the Bis-GMA–based resin being mostly affected. Calcium hydroxide was deposited on the material surface regardless of the type of vehicle used. Formation of beta calcium phosphate was observed on materials containing barium zirconate radiopacifier immersed in HBSS. Inductively coupled plasma emission spectroscopy analysis showed high levels of calcium leached from materials by using water and light-curable resin as mixing vehicles. Barium was leached in solution, with the highest amount from the water-based mixtures. Zirconium leaching was negligible in materials containing zirconium oxide as radiopacifier, but leaching of zirconium was measurable in materials by using barium zirconate with tricalcium silicate.

Conclusions

The resin type and composition of the radiopacifier affect the calcium releasing ability and bioactivity of tricalcium silicate cements. Barium was leached in solution with barium zirconate radiopacified variants. Light-cured Bis-GMA–based resins did not exhibit cement hydration; however, they encouraged leaching of calcium ions in solution and promoted surface deposition of calcium phosphate.     

Mesoporous Calcium Silicate Nanoparticles with Drug Delivery and Odontogenesis Properties

Introduction

Calcium silicate (CS) –based materials play an important role in the development of endodontic materials that induce bone/cementum tissue regeneration and inhibit bacterial viability. The aim of this study was to prepare novel mesoporous CS (MesoCS) nanoparticles that have osteogenic, drug delivery, and antibacterial characteristics for endodontic materials and also have an excellent ability to develop apatite mineralization.

Root Canal Filling Quality of a Premixed Calcium Silicate Endodontic Sealer Applied Using Gutta-percha Cone-mediated Ultrasonic Activation

Introduction

The aim of this study was to investigate the filling quality of a recently developed premixed calcium silicate–based endodontic sealer (Endoseal MTA) with a single gutta-percha (GP) cone technique compared with a resin-based sealer (AH plus) with warm vertical compaction. We also explored the effect of GP cone-mediated ultrasonic activation on the filling quality of Endoseal MTA.

Comparison of Mineral Trioxide Aggregate's Composition with Portland Cements and a New Endodontic Cement

The aim of this study was to compare the compositions of mineral trioxide aggregates (MTAs), Portland cements (PCs), and a new endodontic cement (NEC). Our study also investigated the surface characteristics of MTA and NEC root-end fillings when immersed in normal saline. For part I, we prepared samples of 9 brands of MTAs, PCs, and NEC. The materials were imaged and analyzed by scanning electron microscopy (SEM) and energy dispersive x-ray analysis (EDXA). In part II, 3-mm-deep root-end preparations were filled with MTA or NEC and stored in normal saline for 1 week. Samples were imaged and analyzed by SEM and electron probe microanalysis (EPMA). EDXA investigations revealed differences in the dominant compounds of NEC, PCs, and MTAs. The major components of MTA and PC are the same except for bismuth. The most significant difference was the presence of higher concentrations of Fe (minor element) in gray MTA and PC when compared with white ones. EPMA results revealed remarkably different elements in MTA compared with surrounding dentin, whereas in the NEC group the distribution patterns of calcium, phosphorous, and oxygen were comparable. NEC differs chemically from MTAs and PCs and demonstrates comparable surface composition with adjacent dentin as a root-end filling material.     

硅酸钙生物陶瓷对牙髓细胞体外增殖分化的影响

目的:应用硅酸钙(CaSiO3,CS)生物陶瓷作用于人牙髓细胞(human dental pulp cells,hDPCs),研究其对hDPCs增殖及向成牙本质细胞方向分化的影响。方法:从年轻健康患者(18²0岁)拔除的智齿或前磨牙牙髓组织中获取hDPCs进行培养。将质量浓度为0.2 g/mL的CS浸提液按1/2、1/4、1/8、1/16、1/32、1/64和1/128倍比稀释后作用于hDPCs。MTT实验检测不同质量浓度CS浸提液对hDPCs增殖的影响,进而筛选出最佳浓度。以最佳质量浓度(1/64倍比稀释)CS浸提液培养hDPCs 2、4 d后,Real-Time PCR检测以下hDPCs成牙本质相关基因的表达:牙本质涎磷蛋白(dentin sialophosphoprotein,DSPP)、牙本质基质蛋白-1(dentin matrix protein 1,DMP-1),Ⅰ型胶原(collagen typeⅠ,COL-Ⅰ)、骨钙蛋白(osteocalcin,OCN)、骨桥蛋白(osteopontin,OPN);培养7、14 d后碱性磷酸酶(alkaline phosphatase,ALP)染色及半定量检测ALP活性。结果:最佳质量浓度(1/64倍比稀释)CS浸提液能够促进hDPCs的增殖,对牙髓细胞DSPP、DMP-1、COL-1、OPN等成牙本质相关基因的表达有较为明显的促进作用。ALP染色及半定量分析显示该浓度的CS浸提液能够提高hDPCs分泌ALP的活性。结论:最佳质量浓度(1/64倍比稀释)CS浸提液能够明显促进hDPCs的增殖,提高成牙本质相关基因的表达,进而促进hDPCs向成牙本质细胞方向分化,为后期hDPCs结合CS支架材料进行牙本质再生的研究打下基础。     

新型多孔聚甲基丙烯酸甲酯与磷酸钙骨水泥复合材料的实验研究

目的：制备并研究新型多孔聚甲基丙烯酸甲酯/磷酸钙骨水泥的聚合温度、材料成分、机械特性、孔隙率等临床应用相关特性,为进一步开发理想骨水泥修复材料提供理论依据。方法：在传统聚甲基丙烯酸甲酯骨水泥制备的基础上,以羧甲基纤维素钠和α-磷酸三钙作为成孔剂和骨引导剂,制备不同组分的多孔聚甲基烯酸甲酯/磷酸钙骨水泥,用热电偶、x射线衍射仪、体式显微镜、显微CT和MTS材料试验系统分别评价合成产物的最高聚合温度、材料成分、孔隙率、孔径大小、机械特性等特征。结果：具有骨引导性的α-磷酸三钙能成功载入多孔聚甲基烯酸甲酯支架中,生成的产物具有安全的聚合温度。不同含量的羧甲基纤维素钠会影响支架中孔径的大小,但不会影响孔隙率（P=0.102）。虽然α-磷酸三钙的载入会降低孔隙率（P〈0.001）,但所有产物之间的抗压强度和弹性模量无显著性差异（P=0.724,P=0.601）。结论：多孔聚甲基丙烯酸甲酯支架能与α-磷酸三钙成功复合成具有适宜机械性能的生物材料,这为开发理想骨水泥修复材料提供了新的思路。     

不同孔径新型复合材料硅／磷酸钙修复骨缺损实验研究

目的：探讨不同孔径新型复合材料硅，磷酸钙植入兔下颌骨缺损区的成骨能力。方法：将3种不同孔径硅膦酸钙（大孔型300μm、150μm及致密型）分别植入兔下颌骨缺损区。分别在术后3、6、12周取材进行大体、组织学观察及新骨形成的统计学分析。结果：3种不同孔径硅，磷酸钙在12周均能与邻近骨组织骨性结合：2种大孔型硅，磷酸钙新生骨面积百分比均显著大于致密型硅，磷酸钙（P〈0．01）。结论：大孔型硅，磷酸钙骨引导性、成骨活性优于致密型硅，磷酸钙。     

Regenerative Endodontic Treatment for Necrotic Immature Permanent Teeth

This retrospective study included 23 necrotic immature permanent teeth treated for either short-term (treatment period <3 months) or long-term (treatment period >3 months) using conservative endodontic procedures with 2.5% NaOCl irrigations without instrumentation but with Ca(OH)₂ paste medication. For seven teeth treated short-term, the gutta-percha points were filled onto an artificial barrier of mineral trioxide aggregate (MTA). For 16 teeth treated long-term, the gutta-percha points, amalgam, or MTA were filled onto the Ca(OH)₂-induced hard tissue barrier in the root canal. We found that all apical lesions showed complete regression in 3 to 21 (mean, 8) months after initial treatment. All necrotic immature permanent teeth achieved a nearly normal root development 10 to 29 (mean, 16) months after initial treatment. We conclude that immature permanent teeth with pulp necrosis and apical pathosis can still achieve continued root development after proper short-term or long-term regenerative endodontic treatment procedures.