Aim
To test a novel calcium silicate cement mixed with a water‐based gel (NeoMTA Plus) with regard to chemical–physical properties and apatite‐forming ability.
Methodology
NeoMTA Plus (Avalon Biomed ...Inc. Bradenton, FL, USA; lot. 2014090301) and a commercial MTA‐based material with similar properties (MTA Plus, Prevest Denpro Limited, Jammu, India; lot. 41001) were tested for ion‐releasing ability, initial and final setting times, radiopacity, open and impervious porosity and apparent porosity, water sorption, weight loss, solubility, ability to nucleate calcium phosphates (CaP) after immersion in HBSS (Hank's Balanced Salt Solution) by ESEM‐EDX and micro‐Raman spectroscopy. The results were analysed statistically with the anova test (P < 0.05).
Results
NeoMTA Plus had a prolonged setting time (315 min) and a satisfactory radiopacity (3.76 mm Al). Calcium and hydroxyl ion release was significantly greater and more prolonged in comparison with MTA Plus (P < 0.05). Both NeoMTA Plus and MTA Plus had high values of open porosity and solubility. ESEM‐EDX and micro‐Raman confirmed the ability to nucleate calcium phosphates on their surface after immersion in HBSS.
Conclusion
NeoMTA Plus is a new calcium silicate‐based cement for root filling with an adequate radiopacity and prolonged setting time. The ion release and CaP‐forming ability could increase stability of the root filling and promote endodontic and periodontal tissue regeneration, enhancing the bioactivity and biocompatibility of the material.
Gandolfi MG, Siboni F, Prati C. Chemical–physical properties of TheraCal, a novel light‐curable MTA‐like material for pulp capping. International Endodontic Journal, 45, 571–579, 2012.
Aim To ...evaluate the chemical–physical properties of TheraCal, a new light‐curable pulp‐capping material composed of resin and calcium silicate (Portland cement), compared with reference pulp‐capping materials (ProRoot MTA and Dycal).
Methodology Calcium (Ca) and hydroxyl (OH) ion release over 28 days, solubility and water uptake (weight percentage variation, Δ%) at 24 h, cure depth and radiopacity of TheraCal, ProRoot MTA and Dycal were evaluated. Statistical analysis (P < 0.05) of release of ion was carried out by two‐way repeated measures anova with Tukey, whilst one‐way anova with Tukey test was used for the other tests.
Results TheraCal released significantly more calcium than ProRoot MTA and Dycal throughout the test period. TheraCal was able to alkalinize the surrounding fluid initially to pH 10–11 (3 h–3 days) and subsequently to pH 8–8.5 (7–14 days). TheraCal had a cure depth of 1.7 mm. The solubility of TheraCal (Δ−1.58%) was low and significantly less than that of Dycal (Δ−4.58%) and ProRoot MTA (Δ−18.34%). The amount of water absorbed by TheraCal (Δ +10.42%) was significantly higher than Dycal (Δ +4.87%) and significantly lower than ProRoot MTA (Δ +13.96%).
Conclusions TheraCal displayed higher calcium‐releasing ability and lower solubility than either ProRoot MTA or Dycal. The capability of TheraCal to be cured to a depth of 1.7 mm may avoid the risk of untimely dissolution. These properties offer major advantages in direct pulp‐capping treatments.
Aim
To evaluate the surface and microstructural alterations of new and used HyFlex EDM prototypes and to test their fatigue resistance.
Methodology
Fifteen HyFlex EDM prototypes were used for ...in vitro instrumentation of severely curved root canals. Surface and microstructural characteristics of new and used files were compared by ESEM analysis equipped with energy dispersive X‐ray spectrophotometry (EDS) and optical metallographic imaging. Usage‐induced degradation was assessed. Thirty additional HyFlex EDM prototypes and 20 standard manufactured HyFlex CM files were subjected to cyclic fatigue tests. Time to fracture was recorded, and results were validated using the Kruskal–Wallis test (α‐level 0.05). Fatigued files were analysed by ESEM for fractographic evaluation.
Results
Surface and microstructural characterization of EDM prototypes revealed the typical spark‐machined surface of a NiTi EDM alloy. No fractures were registered during root canal instrumentation. No evident surface alterations and minor degradation were observed between new and used instruments. The metallographic analysis of new and used files disclosed a homogeneous structure, mostly composed of lenticular martensite grains, and some residual austenite. The cyclic fatigue test showed an increase of fatigue resistance up to 700% on the EDM compared to CM files.
Conclusions
Spark‐machined peculiar surface is the main feature of HyFlex EDM. Low degradation was observed after multiple canal instrumentations. Prototypes exhibited surprising high values of cyclic fatigue resistance and a safe in vitro use in severely curved canals.
Gandolfi MG, Taddei P, Tinti A, Prati C. Apatite‐forming ability (bioactivity) of ProRoot MTA. International Endodontic Journal, 43, 917–929, 2010.
Aim Apatite‐forming ability, considered as an ...index of bioactivity (bond‐to‐bone ability), was tested on ProRoot MTA cement after immersion in phosphate‐containing solution (DPBS).
Methodology Disk samples were prepared and immersed in DPBS for 10 min, 5 h, 1 and 7 days. The cement surface was studied by attenuated total reflectance Fourier transform infrared (ATR‐FTIR) spectroscopy, by micro‐Raman spectroscopy and by environmental scanning electron microscope with energy dispersive X‐ray (ESEM‐EDX) analyses. The pH of the storage solution was also investigated.
Results Spectroscopic analyses revealed calcium phosphate bands after 5‐h immersion in DPBS. After 1 day, an even coating composed of apatite spherulites (0.1–0.8 micron diameter) was observed by ESEM/EDX. After 7 days, its thickness had increased. Apatite nucleation had already occurred after 5‐h immersion. At this time, the presence of portlandite (i.e. Ca(OH)2, calcium hydroxide) on the cement surface was also observed; at longer times, this component was released into the medium, which underwent a remarkable pH increase.
Conclusions The study confirms the ability of ProRoot MTA to form a superficial layer of apatite within hours. The excellent bioactivity of ProRoot MTA might provide a significant clinical advantage over the traditional cements used for root‐end or root‐perforation repair.
Aim
To evaluate the chemical and physical properties of a tricalcium silicate root canal sealer containing povidone and polycarboxylate (BioRoot RCS), a calcium silicate MTA‐based sealer containing a ...salicylate resin (MTA Fillapex), a traditional eugenol‐containing sealer (Pulp Canal Sealer) and an epoxy resin‐based root canal sealer (AH Plus).
Methodology
Calcium release, pH, setting time, water sorption, volume of open pores, volume of impervious portion, apparent porosity and weight loss were measured. The ability to nucleate calcium phosphates (CaP) after ageing 28 days in a simulated body fluid was evaluated using ESEM‐EDX and micro‐Raman spectroscopy. Data were statistically analysed (P = 0.05) using one‐way anova (setting time, radiopacity, solubility, water sorption, porosity) or two‐way anova (ion release tests).
Results
BioRoot RCS had a final setting time of 300 min and adequate radiopacity (5.2 mm Al). It demonstrated the highest (P < 0.05) and more prolonged ability to release calcium ions (721 ppm at 3 h) and to increase the pH (11–12) (P < 0.05); B‐type carbonated apatite deposits were found on aged BioRoot RCS (biointeractivity‐related CaP‐forming ability). A final setting time of 270 min and good calcium release (17.4 ppm at 3 h) were measured for MTA Fillapex; apatite deposits were present on aged samples. No calcium release and no alkalizing activity were measured for Pulp Canal Sealer and AH Plus; no CaP nucleation was detected on aged Pulp Canal Sealer, and some apatite deposits were found on aged AH Plus (chemi/physisorption‐related CaP‐deposition). Higher and significantly different (P < 0.05) porosity, water sorption and solubility were measured for the two calcium silicate sealers, especially for BioRoot RCS.
Conclusions
BioRoot RCS had bioactivity with calcium release, strong alkalizing activity and apatite‐forming ability, and adequate radiopacity.
Abstract Objective To study the in vivo osteoinductive potential, bone-bonding ability (bioactivity) and bone biomineralization of current hydraulic calcium silicate cements used as graft materials ...and placed in contact with medullary bone. Methods ProRoot MTA, MTA Plus and Biodentine were used to fill surgical bone defects (2-mm diameter through the entire cortical thickness to reach the medullary bone) in the tibia of mature male rabbits. Tibiae were retrieved after 30 days and submitted to histological analysis and microchemical characterization using Optical Microscopy (OM) and Environmental Scanning Electron Microscopy with Energy Dispersive X-ray analysis (ESEM-EDX). Bone neoformation and histomorphometric evaluations, degree of mineralization (by Ca/P, Ca/N and P/N ratios) and the diffusion of material elements were studied. Results Bone neoformation was observed in response to all materials. No sign of necrosis were found on the walls of the pre-existing cortical bone. No osteoclasts and no formation of fibrous tissue were evident. Sign of angiogenesis were present. EDX (element content, line profile and element mapping) showed the increase in Ca and P and decrease in C, S and N from the mature bone towards the mineralizing interface. Ca/P, Ca/N and P/N ratios showed differences in the degree of mineralization/maturation stage of bone. MTA Plus and ProRoot MTA exhibited close contact with the pre-existing bone and good bone-bonding with neoformed bone juxtaposed on the medullary side of the materials without interposed connective tissue or resorption lacunae or gaps. The materials showed a dense appearance with 100% of residual materials and no colonization by fluids and cells. No migration of Bi or Al material elements to the newly formed bone was found. Biodentine showed newly formed trabecular bone with marrow spaces and sparse traces of residual material (≈9%). Significance The in vivo osteoinductive properties with dynamic biomineralization processes around these calcium silicate materials extruded in medullary bone in appropriate animal model have been demonstrated by ESEM-EDX in association with OM. Good biocompatibility was evident as only slight inflammatory infiltrate and no sign of necrosis at the interface with the pre-existing bone were found. MTA Plus and ProRoot MTA exhibited bioactive potential as they can bond to bone directly without interposed connective tissue. Biodentine was replaced by newly formed bone. Clinical significance The results of the study demonstrate the capacity of calcium silicate cements to allow osteoid matrix deposition by activated osteoblasts and favour its biomineralization, and to achieve a direct bond between the (bioactive) materials surface and the mineralized bone matrix.
Abstract Objective Root canal filling sealers based on polymethyl hydrogensiloxane or polymethyl hydrogensiloxane-guttapercha – introduced to improve the quality of conventional guttapercha-based and ...resin-based systems – showed advantages in handiness and clinical application. The aim of the study was to evaluate the chemical–physical properties of a novel polysiloxane-guttapercha calcium silicate-containing root canal sealer (GuttaFlow bioseal). Methods GuttaFlow bioseal was examined and compared with GuttaFlow2, RoekoSeal and MTA Fillapex sealers. Setting times, open and impervious porosity and apparent porosity, water sorption, weight loss, calcium release, and alkalinizing activity were evaluated. ESEM-EDX-Raman analyses of fresh materials and after soaking in simulated body fluid were also performed. Results Marked differences were obtained among the materials. GuttaFlow bioseal showed low solubility and porosity, high water sorption, moderate calcium release and good alkalinizing activity. MTA Fillapex showed the highest calcium release, alkalinizing activity and solubility, RoekoSeal the lowest calcium release, no alkalinizing activity, very low solubility and water sorption. Only GuttaFlow bioseal showed apatite forming ability. Significance GuttaFlow bioseal showed alkalinizing activity together with negligible solubility and slight calcium release. Therefore, the notable nucleation of apatite and apatite precursors can be related to the co-operation of CaSi particles (Si OH groups) with polysiloxane (Si O Si groups). The incorporation of a calcium silicate component into polydimethyl polymethylhydrogensiloxane guttapercha sealers may represent an attractive strategy to obtain a bioactive biointeractive flowable guttapercha sealer for moist/bleeding apices with bone defects in endodontic therapy.
Aim
To compare the phase transformation behaviour, the microstructure, the nano‐hardness and the surface chemistry of electro‐discharge machined HyFlex EDM instruments with conventionally ...manufactured HyFlex CM.
Methodology
New and laboratory used HyFlex EDM were examined by X‐ray diffraction (XRD) and differential scanning calorimetry (DSC). Nano‐hardness and modulus of elasticity were also investigated using a maximum load of 20 mN with a minimum of 40 significant indentations for each sample. Raman spectroscopy and field emission‐scanning electron microscope (FE‐SEM) were used to assess the surface chemistry of HyFlex EDM. HyFlex CM were subjected to the same investigations and used as a comparison. Nano‐indentation data were statistically analysed using the Student's t‐test.
Results
XRD analysis on HyFlex EDM revealed the presence of martensite and rhombohedral R‐phase, while a mixture of martensite and austenite structure was identified in HyFlex CM. DSC analysis also disclosed higher austenite finish (Af) temperatures for electro‐discharge machining (EDM) instruments. Significant differences in nano‐hardness and modulus of elasticity were found between EDM and CM files (P < 0.05). FE‐SEM and EDS analyses confirmed that both new EDM and CM files were covered by an oxide layer. Micro‐Raman spectroscopy assessed the presence of rutile‐TiO2
.
Conclusions
HyFlex EDM revealed peculiar structural properties, such as increased phase transformation temperatures and hardness. Present results corroborated previous findings and shed light on the enhanced mechanical behaviour of these instruments.
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