Francesco Siboni

Development of the foremost light-curable calcium-silicate MTA cement as root-end in oral surgery. Chemical–physical properties, bioactivity and biological behavior

AIM An innovative light-curable calcium-silicate cement containing a HEMA-TEGDMA-based resin (lc-MTA) was designed to obtain a bioactive fast setting root-end filling and root repair material. METHODS lc-MTA was tested for setting time, solubility, water absorption, calcium release, alkalinizing activity (pH of soaking water), bioactivity (apatite-forming ability) and cell growth-proliferation. The apatite-forming ability was investigated by micro-Raman, ATR-FTIR and ESEM/EDX after immersion at 37°C for 1-28 days in DPBS or DMEM+FBS. The marginal adaptation of cement in root-end cavities of extracted teeth was assessed by ESEM/EDX, and the viability of Saos-2 cell on cements was evaluated. RESULTS lc-MTA demonstrated a rapid setting time (2min), low solubility, high calcium release (150-200ppm) and alkalinizing power (pH 10-12). lc-MTA proved the formation of bone-like apatite spherulites just after 1 day. Apatite precipitates completely filled the interface porosities and created a perfect marginal adaptation. lc-MTA allowed Saos-2 cell viability and growth and no compromising toxicity was exerted. SIGNIFICANCE HEMA-TEGDMA creates a polymeric network able to stabilize the outer surface of the cement and a hydrophilic matrix permeable enough to allow water absorption. SiO(-)/Si-OH groups from the mineral particles induce heterogeneous nucleation of apatite by sorption of calcium and phosphate ions. Oxygen-containing groups from poly-HEMA-TEGDMA provide additional apatite nucleating sites through the formation of calcium chelates. The strong novelty was that the combination of a hydraulic calcium-silicate powder and a poly-HEMA-TEGDMA hydrophilic resin creates the conditions (calcium release and functional groups able to chelate Ca ions) for a bioactive fast setting light-curable material for clinical applications in dental and maxillofacial surgery. The first and unique/exclusive light-curable calcium-silicate MTA cement for endodontics and root-end application was created, with a potential strong impact on surgical procedures.

Chemical-physical properties of TheraCal, a novel light-curable MTA-like material for pulp capping.

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.

Setting time and expansion in different soaking media of experimental accelerated calcium-silicate cements and ProRoot MTA.

OBJECTIVES The setting time and the expansion in deionized water, phosphate-buffered saline (PBS), 20% fetal bovine serum (FBS)/80% PBS or hexadecane oil of experimental accelerated calcium-silicate cements and ProRoot MTA were evaluated. STUDY DESIGN Different compounds such as sodium fluoride, strontium chloride, hydroxyapatite, and tricalcium phosphate were separately added to a basic experimental calcium-silicate cement to test their effect on setting and expansion. The initial and final setting times were determined using appropriate Gilmore needles. A linear variable differential transformer (LVDT) device was used to test the restricted hygroscopic linear expansion over 180 minutes of cements immersed in different solutions. Results were statistically compared using a 2-way ANOVA test (cement type versus solution type). RESULTS All experimental cements showed initial setting times between 28 and 45 minutes and final setting times between 52 and 80 minutes. MTA showed a final setting time of 170 minutes. Final setting time of all experimental cements was faster than MTA. All cements showed slight (0.04%-0.77%) expansion in water, PBS, or FBS/PBS. Only fluoride-containing cement showed a significant expansion in water (6.68%) and in PBS (6.72%). The PBS/FBS contamination significantly reduced the expansion of fluoride-containing cement (2.98%) and MTA (0.07%). In contrast, cements showed a slight shrinkage when immersed in hexadecane, especially fluoride-containing cement. CONCLUSIONS The study demonstrated that: (1) the setting time of calcium-silicate cements may be effectively reduced; (2) the expansion is a water dependent mechanism owing to water uptake, because no expansion occurred in cements immersed in oil; (3) a correlation between setting time and expansion in water and PBS exists; (4) fluorine-containing cement showed a significant expansion in water and in PBS; (5) the immersion in FBS/PBS strongly reduced the expansion of MTA and fluoride-doped cement suggesting that fluid contamination (ie, blood) during surgical procedures may greatly affect the expansion of some calcium-silicate cements.

Biointeractivity‐related versus chemi/physisorption‐related apatite precursor‐forming ability of current root end filling materials

Commercial root end filling materials, namely two zinc oxide eugenol-based cements [intermediate restorative material (IRM), Superseal], a glass ionomer cement (Vitrebond) and three calcium-silicate mineral trioxide aggregate (MTA)-based cements (ProRoot MTA, MTA Angelus, and Tech Biosealer root end), were examined for their ability to: (a) release calcium (Ca(2+) ) and hydroxyl (OH(-) ) ions (biointeractivity) and (b) form apatite (Ap) and/or calcium phosphate (CaP) precursors. Materials were immersed in Hanks balanced salt solution (HBSS) for 1-28 days. Ca(2+) and OH(-) release were measured by ion selective probes, surface analysis was performed by environmental scanning electron microscopy/energy dispersive X-ray analysis, micro-Raman, and Fourier transform infrared spectroscopy. IRM and Superseal released small quantities of Ca(2+) and no OH(-) ions. Uneven sparse nonapatitic Ca-poor amorphous CaP (ACP) deposits were observed after 24 h soaking. Vitrebond did not release either Ca(2+) or OH(-) ions, but uneven nonapatitic Ca-poor CaP deposits were detected after 7 days soaking. ProRoot MTA, MTA Angelus, and Tech Biosealer root end released significant amounts of Ca(2+) and OH(-) ions throughout the experiment. After 1 day soaking, nanospherulites of CaP deposits formed by amorphous calcium/magnesium phosphate (ACP) Ap precursors were detected. A more mature ACP phase was present on ProRoot MTA and on Tech Biosealer root end at all times. In conclusion, zinc oxide and glass ionomer cements had little or no ability to release mineralizing ions: they simply act as substrates for the possible chemical bonding/adsorption of environmental ions and precipitation of nonapatitic Ca-poor ACP deposits. On the contrary, calcium-silicate cements showed a high calcium release and basifying effect and generally a pronounced formation of more mature ACP apatitic precursors correlated with their higher ion-releasing ability.

Dynamic sealing ability of MTA root canal sealer

AIMS To evaluate (i) the sealing ability of two sealers, mineral trioxide aggregate sealer (MTAS) and Pulp Canal Sealer (PCS), used with gutta-percha utilizing the fluid filtration method, (ii) leaching and surface characteristics in Hanks balanced salt solution (HBSS) over a period of time. METHODOLOGY Surface characteristics in HBSS were evaluated under the scanning electron microscope after 1 and 28 days, and the leaching of both sealers were assessed by inductively coupled plasma atomic absorption spectrometry (ICP-AAS). In addition, 24 single rooted extracted teeth were root filled using warm vertical compaction with either MTAS or PCS used as sealers with gutta-percha. Four teeth were used as positive and negative controls. Sealing ability was evaluated after 1 or 28 days using the fluid filtration method. RESULTS Mineral trioxide aggregate sealer exhibited crystalline deposits rich in calcium and phosphorus on its surface when in contact with a physiological solution. These crystalline deposits were absent in PCS and on MTAS stored at 100% humidity. The sealing ability of MTAS was similar to that of PCS. CONCLUSIONS The novel sealer based on mineral trioxide aggregate had comparable sealing ability to a proprietary brand sealer cement. In contact with a simulated body fluid, the MTA sealer released calcium ions in solution that encouraged the deposition of calcium phosphate crystals.

Calcium silicate and calcium hydroxide materials for pulp capping: Biointeractivity, porosity, solubility and bioactivity of current formulations

Aim The chemical-physical properties of novel and long-standing calcium silicate cements versus conventional pulp capping calcium hydroxide biomaterials were compared. Methods Calcium hydroxide–based (Calxyl, Dycal, Life, Lime-Lite) and calcium silicate–based (ProRoot MTA, MTA Angelus, MTA Plus, Biodentine, Tech Biosealer capping, TheraCal) biomaterials were examined. Calcium and hydroxyl ion release, water sorption, interconnected open pores, apparent porosity, solubility and apatite-forming ability in simulated body fluid were evaluated. Results All calcium silicate materials released more calcium. Tech Biosealer capping, MTA Plus gel and Biodentine showed the highest values of calcium release, while Lime-Lite the lowest. All the materials showed alkalizing activity except for Life and Lime-Lite. Calcium silicate materials showed high porosity values: Tech Biosealer capping, MTA Plus gel and MTA Angelus showed the highest values of porosity, water sorption and solubility, while TheraCal the lowest. The solubility of water-containing materials was higher and correlated with the liquid-to-powder ratio. Calcium phosphate (CaP) deposits were noted on materials surfaces after short aging times. Scant deposits were detected on Lime-Lite. A CaP coating composed of spherulites was detected on all calcium silicate materials and Dycal after 28 days. The thickness, continuity and Ca/P ratio differed markedly among the materials. MTA Plus showed the thickest coating, ProRoot MTA showed large spherulitic deposits, while TheraCal presented very small dense spherulites. Conclusions calcium silicate-based cements are biointeractive (ion-releasing) bioactive (apatite-forming) functional biomaterials. The high rate of calcium release and the fast formation of apatite may well explain the role of calcium silicate biomaterials as scaffold to induce new dentin bridge formation and clinical healing.

Fluoride-containing nanoporous calcium-silicate MTA cements for endodontics and oral surgery: early fluorapatite formation in a phosphate-containing solution

AIM To test the chemical-physical properties and apatite-forming ability of experimental fluoride-doped calcium silicate cements designed to create novel bioactive materials for use in endodontics and oral surgery. METHODOLOGY A thermally treated calcium silicate cement (wTC) containing CaCl(2) 5%wt was modified by adding NaF 1%wt (FTC) or 10%wt (F10TC). Cements were analysed by environmental scanning electron microscopy with energy-dispersive X-ray analysis, IR and micro-Raman spectroscopy in wet conditions immediately after preparation or after ageing in a phosphate-containing solution (Dulbeccos phosphate-buffered saline). Calcium and fluoride release and pH of the storage solution were measured. The results obtained were analysed statistically (Tukeys HSD test and two-way anova). RESULTS The formation of calcium phosphate precipitates (spherulites) was observed on the surface of 24 h-aged cements and the formation of a thick bone-like B-type carbonated apatite layer (biocoating) on 28 day-aged cements. The rate of apatite formation was FTC>F10TC>wTC. Fluorapatite was detected on FTC and F10TC after 1 day of ageing, with a higher fluoride content on F10TC. All the cements released calcium ions. At 5 and 24 h, the wTC had the significantly highest calcium release (P<0.001) that decreased significantly over the storage time. At 3-28 days, FTC and F10TC had significantly higher calcium release than wTC (P<0.05). The F10TC had the significantly highest fluoride release at all times (P<0.01) that decreased significantly over storage time. No significant differences were observed between FTC and wTC. All the cements had a strong alkalinizing activity (OH(-) release) that remained after 28 days of storage. CONCLUSIONS The addition of sodium fluoride accelerated apatite formation on calcium silicate cements. Fluoride-doped calcium silicate cements had higher bioactivity and earlier formation of fluorapatite. Sodium fluoride may be introduced in the formulation of mineral trioxide aggregate cements to enhance their biological behaviour. F-doped calcium silicate cements are promising bone cements for clinical endodontic use.

Calcium silicate/calcium phosphate biphasic cements for vital pulp therapy: chemical-physical properties and human pulp cells response

ObjectivesThe aim was to test the properties of experimental calcium silicate/calcium phosphate biphasic cements with hydraulic properties designed for vital pulp therapy as direct pulp cap and pulpotomy.MethodsCaSi-αTCP and CaSi-DCDP were tested for ion-releasing ability, solubility, water sorption, porosity, ability to nucleate calcium phosphates, and odontoblastic differentiation—alkaline phosphatase (ALP) and osteocalcin (OCN) upregulation—of primary human dental pulp cells (HDPCs).ResultsThe materials showed high Ca and OH release, high open pore volume and apparent porosity, and a pronounced ability to nucleate calcium phosphates on their surface. HDPCs treated with CaSi-αTCP showed a strong upregulation of ALP and OCN genes, namely a tenfold increase for OCN and a threefold increase for ALP compared to the control cells. Conversely, CaSi-DCDP induced a pronounced OCN gene upregulation but had no effect on ALP gene regulation.ConclusionsBoth cements showed high biointeractivity (release of Ca and OH ions) correlated with their marked ability to nucleate calcium phosphates. CaSi-αTCP cement proved to be a potent inducer of ALP and OCN genes as characteristic markers of mineralization processes normally poorly expressed by HDPCs.Clinical relevanceCalcium silicate/calcium phosphate cements appear to be attractive new materials for vital pulp therapy as they may provide odontogenic/dentinogenic chemical signals for pulp regeneration and healing, and dentin formation in regenerative endodontics.

Properties of a novel polysiloxane-guttapercha calcium silicate-bioglass-containing root canal sealer

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 (SiOH groups) with polysiloxane (SiOSi 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.

Use of calcium-containing endodontic sealers as apical barrier in fluid-contaminated wide-open apices.

Purpose The sealing of wide-open apex roots is still a challenge and requires the use of apical barrier techniques. The aim was to evaluate ex vivo the sealing and the apical morphology of 3 commercial calcium oxide (CaO)-containing sealers - namely, 2 zinc oxide-based (CRCS and Sealapex) and a calcium silicate MTA-based (TechBiosealer Endo) - placed in wet root canals with artificial wide-open apices. Methods Thirty human single-rooted teeth were shaped with Protaper and an artificial open apex (diameter size 110) was created. Each root was inserted in a custom-designed support containing simulated body fluid (Hanks balanced salt solution, HBSS) at the bottom simulating the presence of periapical fluid in the canal. Each sealer (TechBiosealer Endo, CRCS, Sealapex) was compacted to the apical 5 mm and the filled roots stored in HBSS at 37°C. The sealing was evaluated as micro-infiltrated fluid since 24 hours up to 6 months using a high-precision digital fluid flow meter. The sealers were also studied for setting time in HBSS, calcium releasing (statistical analysis by 2-way ANOVA followed by Student-Newman-Keuls test, P<0.05) and surface morpho-chemistry by environmental scanning electron microscope with energy dispersive X-ray (ESEM-EDX) and optical microscopy (OM) analysis. Results All sealers showed a stable seal. TechBiosealer Endo maintained a better seal than the other materials (P<0.05) and ESEM-EDX and OM analyses showed the presence of apatite deposits. Conclusions The clinical use of hydraulic hydrophilic MTA-based sealers can be recommended to stop/reduce the fluid flow rate through the apex. The artificial apical barrier in wet wide apices is a suitable technique able to seal wet root canals.