Root canal treatment of compromised teeth as alternative treatment for patients receiving bisphosphonates: 60-month results of a prospective clinical study.

AIM: This 60-month prospective study aimed to evaluate tooth survival and healing rates after root canal treatment in patients taking bisphosphonates (BPs). Secondary outcomes were complications and clinical variables observed during and after treatment. METHODS: Root canal treatment was performed using manual K-file canal instrumentation and a carrier-based filling technique with an epoxy resin-based sealer. Teeth without adequate root/crown integrity were restored by trained operators at the tissue level (TL group) to prevent occlusal/mechanical stress and to enable periapical lesion healing without the risk of root fracture. Other teeth were restored with normal occlusal contacts (OC group). Healthy patients who had undergone one or more root canal treatments of the same type constituted the control group. The relationships of the following variables to survival and health status were examined (chi-squared test and multivariate analysis, P = 0.05): age, gender, smoking habit, tooth location, treatment type, BPs treatment, BPs exposure, initial periapical index (PAI) and occlusal restoration. Survival curves were constructed using Kaplan-Meier analysis, with extraction serving as the end-point. RESULTS: In total, 65 patients with 109 root canal-treated teeth who were taking BPs were included. At 60 months, data from 57 patients (52F, 5M; median age 65.7 ± 8.6 years) who had undergone 96 root canal treatments were analysed (drop-out rate = 16.9%). The survival rate was 85%, and the success rate was 76%. The control group consisted of 46 patients (21F, 25M; median age 60.3 ± 7.2 years) who had undergone 102 root canal treatments. The survival rate was 88%, with 12 teeth lost during follow-up. The success rate was 73%. In the BP group, 55 teeth were restored normally (OC group) and 41 teeth were restored at the tissue level (TL group). No difference in the success or survival rate was observed between the BP and control groups (P > 0.05). Univariate Kaplan-Meier analysis revealed that only tooth type significantly affected survival status in the BP group. The analysis revealed the clinical relevance of smoking, tooth location and initial PAI on patients' health status (P < 0.05). CONCLUSION: Root canal treatments and post-endodontic restoration with tissue-level filling procedures represent a safe approach for severely damaged teeth in patients receiving BPs having comparable results to root filled teeth restored with occlusal contacts and to the control group.

A 20-year historical prospective cohort study of root canal treatments. A Multilevel analysis.

AIM: To evaluate the number of healthy and functional root filled teeth of patients included in a recall programme for at least 20 years. METHODOLOGY: Teeth were root filled by a single specialist following manual canal instrumentation, lateral/vertical compaction of gutta-percha and restored with glass-ionomer cements and bonding system/composite resin. In a large percentage of teeth, a metal-ceramic crown was placed during follow-up. Patients included in the recall programme (n = 130) were blindly assessed both clinically and radiographically (every 2 years) to evaluate clinical symptoms and periapical status (PAI). The following variables were analysed: age, tooth location, tooth type, initial diagnosis, PAI, root filling length and coronal restoration type. Chi-square test and multilevel analysis were performed to detect variables associated with treatment functionality and disease/lesions (P < 0.05). A cumulative teeth survival curve was constructed by means of Kaplan-Meier using extractions as the end-point. RESULTS: At the 20-year recall, 72 patients (31 M, 41 F; mean age 57.7 ± 8.29 years; 196 teeth) completed the follow-up. Thirty-six patients were excluded for medical complications or died before the end of the study. Drop-outs consisted of 22 patients (17%) who did not complete the follow-up. Single metal-ceramic crowns were positioned after 4-6 months in 40% of teeth. Composite restorations were replaced with single metal-ceramic crowns during the follow-up in 53% of teeth after 8-19 years. Of 196 teeth, 155 were classified as Survived (79%), 128 of which (65%) were Healthy (PAI ≤ 2). Thirty-nine teeth (20%) were extracted for nonendodontic reasons. Twenty-nine teeth (15%) were classified as: re-exacerbation (11 teeth; 5.6%) or persistent asymptomatic lesions (18 teeth; 9%). Only two re-exacerbated teeth were extracted. Multilevel analysis confirmed the clinical relevance of tooth type (P = 0.001) on Survived and healthy teeth (P = 0.007). Tooth location (P = 0.0045) and initial diagnosis (P = 0.019) significantly affected only Healthy teeth. CONCLUSIONS: Root filled teeth were more frequently extracted for non-endodontic reasons rather than for endodontic disease. The majority of teeth with adequate root fillings, adequate restorations and included in a recall programme remained functional and healthy for more than 20 years.

Survival and periapical health after root canal treatment with carrier-based root fillings: five-year retrospective assessment.

AIM: This retrospective study explored survival and periapical healing outcomes in teeth root filled with Thermafil obturators. METHODOLOGY: Root canals of 213 teeth (94 subjects, mean age 48 ± 13 years), instrumented with a step-down technique, irrigated with 5% NaOCl and 10% EDTA and filled with Thermafil and AH Plus sealer, were involved in a recall programme. Teeth were retrospectively re-examined after 5 ± 1 years in a controlled environment. Clinical and radiographic data that were collected included the following: preoperative Periapical Index (PAI) score and signs/symptoms, treatment type, root filling length and presence/absence of voids, restoration type, follow-up PAI score and signs/symptoms. Teeth were considered 'healthy' (PAI ≤ 2, no signs/symptoms) or 'diseased' (PAI ≥ 3, signs/symptoms present, retreated, extracted for endodontic reasons). Two PAI-calibrated examiners assessed outcomes blinded to preoperative status. Bivariate and multilevel analyses were performed at level of patient and tooth (α = 5%). RESULTS: Of 213 teeth treated, 187 (88%) survived and 26 were extracted, six (3%) for persistent endodontic infection (considered 'diseased'), and 20 (9%) for root fracture, periodontal disease or coronal fracture (excluded from analysis). Whilst survival was significantly associated with tooth type (P = 0.015), type of treatment (P = 0.012) and pulpal/periapical diagnosis (P = 0.035), none of these variables were substantiated as survival predictors by the multilevel analysis. A total of 164 of 193 teeth (85%) were assessed as 'healthy', with significantly higher (chi-square; P < 0.04) 'healthy' rates for teeth with PAI score ≤2 and root fillings of adequate length. Multilevel analysis identified PAI score ≤2 (P = 0.002) as the only predictor of periapical health. CONCLUSIONS: In this 5 ± 1 year retrospective assessment, survival and healing rates after root canal treatment with Thermafil root fillings were comparable to those previously reported for conventional root filling techniques.

Properties of BioRoot RCS, a tricalcium silicate endodontic sealer modified with povidone and polycarboxylate.

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.

Properties of NeoMTA Plus and MTA Plus cements for endodontics.

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.

Structural analysis of HyFlex EDM instruments.

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.

Double dye technique and fluid filtration test to evaluate early sealing ability of an endodontic sealer.

OBJECTIVES: The aim of the present study is to evaluate the possible correlation between sealer penetration into dentinal tubules and sealing ability both in presence and absence of smear layer. MATERIALS AND METHODS: Fourteen maxillary central incisors were treated with 5.25 % NaOCl +10 % EDTA to remove the smear layer (SL-free group) or 5.25 % NaOCl without EDTA (SL group). Root canals were filled using #25 Thermafil Obturators with Topseal sealer labelled with 0.1 wt% rhodamine B. Sealing ability was measured as fluid filtration rate with a fluid-flow meter using water supplemented with 0.3 % calcein fluorescent dye. Specimens were sectioned, observed under confocal microscope to co-localize the presence of sealer (rhodamine B labelling) into dentinal tubules and gaps (calcein labelling) into the root canal. The depth of sealer penetration into dentinal tubules and the percentage of sealer penetration around the root canal were measured at 3, 5 and 8 mm from the apex. RESULTS: No significant differences between groups were observed in fluid filtration rate nor in depth of calcein penetration. Sealer penetration depth and percentage into dentinal tubules were not significantly different between groups, except at 8-mm level in absence of smear layer. CONCLUSION: Sealer penetration at 3- and 5-mm levels was not influenced by smear layer while it was significantly reduced at 8-mm level. Fluid filtration rate was not correlated either with depth of calcein penetration nor with sealer penetration into dentinal tubules. CLINICAL RELEVANCE: The sealing ability of Topseal sealer is not affected by presence or absence of smear layer.

HyFlex EDM: superficial features, metallurgical analysis and fatigue resistance of innovative electro discharge machined NiTi rotary instruments.

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.

Micro-topography and reactivity of implant surfaces: an in vitro study in simulated body fluid (SBF).

The creation of micro-textured dental implant surfaces possessing a stimulating activity represents a challenge in implant dentistry; particularly, the formation of a thin, biologically active, calcium-phosphate layer on their surface could help to strengthen the bond to the surrounding bone. The aim of the present study was to characterize in terms of macrostructure, micro-topography and reactivity in simulated body fluid (SBF), the surface of titanium (Ti) implants blasted with TiO2 particles, acid etched with hydrofluoric acid, and activated with Ca and Mg-containing nanoparticles. Sandblasted and acid-etched implants were analyzed by ESEM-EDX (environmental scanning electron microscope with energy dispersive X-ray system) to study the micromorphology of the surface and to perform elemental X-ray microanalysis (microchemical analyses) and element mapping. ESEM-EDX analyses were performed at time 0 and after a 28-day soaking period in SBF Hank's balanced salt solution (HBSS) following ISO 23317 (implants for surgery­in vitro evaluation for apatite-forming ability of implant materials). Microchemical analyses (weight % and atomic %) and element mapping were carried out to evaluate the relative element content, element distribution, and calcium/phosphorus (Ca/P) atomic ratio. Raman spectroscopy was used to assess the possible presence of impurities due to manufacturing and to investigate the phases formed upon HBSS soaking. Micro-morphological analyses showed a micro-textured, highly rough surface with microgrooves. Microchemical analyses showed compositional differences among the apical, middle, and distal thirds. The micro-Raman analyses of the as-received implant showed the presence of amorphous Ti oxide and traces of anatase, calcite, and a carbonaceous material derived from the decomposition of an organic component of lipidic nature (presumably used as lubricant). A uniform layer of Ca-poor calcium phosphates (CaPs) (Ca/P ratio <1.47) was observed after soaking in HBSS; the detection of the 961 cm⁻¹ Raman band confirms this finding. These implants showed a micro-textured surface supporting the formation of CaPs when immersed in SBF. These properties may likely favor bone anchorage and healing by stimulation of mineralizing cells.

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

OBJECTIVES: The 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. METHODS: CaSi-αTCP and CaSi-DCDP were tested for ion-releasing ability, solubility, water sorption, porosity, ability to nucleate calcium phosphates, and odontoblastic differentiation­alkaline phosphatase (ALP) and osteocalcin (OCN) upregulation­of primary human dental pulp cells (HDPCs). RESULTS: The 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. CONCLUSIONS: Both 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 RELEVANCE: Calcium 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.

The response of cementoblasts to calcium phosphate resin-based and calcium silicate-based commercial sealers.

AIM: To investigate cell viability and gene expression of cementoblasts (OCCM.30) exposed to extractable components released by resin-based sealers with different chemical composition Hybrid Root Seal (HRS), SimpliSeal (SS), Real Seal (RS) and AH Plus (AH) and by a MTA-based sealers Tech Biosealer Endo (TBE). METHODOLOGY: Discs of all materials were prepared and allowed to set in humid conditions at 37° for 48 h. The discs were then incubated for 72 h at 37 °C to obtain material extracts (1/1) in DMEM. The extracts containing the components released by the sealers were filtered and other dilutions (1/2, 1/4) were prepared from the original solution (1/1). Original and diluted solutions were tested on the cementoblasts. Impedance-based real-time cell analysis (RTCA) was used to evaluate cell viability, quantitative real-time polymerase chain reaction (QRT-PCR) was used to examine the expression of mineralization-related genes (osteocalcin; OCN, Runt-related transcription factor-2; Runx2, collagen type 1; COL I, alkaline phosphatase; ALP). For statistical analysis, one-way analysis of variance (anova) and Tukey's honestly significant difference (HSD) tests were used. RESULTS: TBE (1/2), RS (1/2, 1/4), and HRS (1/2, 1/4) significantly decreased cell viability (P < 0.001). AH (1/2, 1/4) and SS (1/2, 1/4) had similar cell viability to the control at 30 h. All tested materials significantly decreased cell viability when compared to the control group except AH (1/2, 1/4) and SS (1/4) at 90 h. All of the tested sealers reduced COL I mRNA expressions when compared to the control. SS was associated with significant increases in OCN and Runx2 mRNA expressions when compared to the control (P < 0.001). Whereas all of the dilutions of TBE, RS and HRS significantly decreased BSP mRNA expressions (P < 0,001), 1/2 and 1/4 dilutions of SS increased BSP mRNA expression (P < 0,001). Except the 1/4 dilutions of AH and SS, all the sealer dilutions significantly reduced ALP mRNA expression in cementoblasts (P < 0,001). CONCLUSIONS: SimpliSeal and AH Plus resulted in more favourable response to cementoblasts because of their regulation potential on the mineralized tissue-associated protein's mRNA expressions.

3D micro-CT analysis of the interface voids associated with Thermafil root fillings used with AH Plus or a flowable MTA sealer.

AIM: To investigate nondestructively the percentage of 3D voids and marginal gaps in a pre-defined interface volume of interest (VOI) within root fillings produced by Thermafil Obturators with either a hydrophobic epoxy-resin-based sealer (AH Plus) or a hydrophilic flowable calcium-silicate sealer [mineral trioxide aggregate (MTA) Flow]. METHODOLOGY: Sixteen single root canals from extracted premolar teeth were prepared with ProTaper rotary instruments, randomly allocated into two groups (n = 8) and filled with size 30 Thermafil Obturators in association with AH Plus or MTA Flow sealers. The filled roots were stored at 37 °C in 5 mL of Hank's balanced salt solution (HBSS) used to represent body fluids and scanned after 7 days and 6 months using a high-resolution micro-CT. From each root, images of 3000 sections were analysed in 3D and binarized using a high-resolution micro-CT (4-µ resolution). The 3D distribution of voids (porosity and marginal gaps) at the gutta-percha-sealer-dentine interface was detected through a threshold grey level and expressed as percentage of the 40-µ-thick pre-defined interface VOI (20 µ of interface dentine and 20 µ of gutta-percha/sealer). A method of analysis based on the root canal segmentation was used, and coronal, middle and apical thirds considered separately. The percentage of 3D void volume was compared statistically using one-way anova (significance for P < 0.05). Environmental Scanning Electron Microscope with Energy Dispersive X-ray (ESEM-EDX) analysis was performed on the surface of both sealers after soaking in HBSS. RESULTS: Micro-CT detected gaps at the dentine-sealer interface in both groups. Void volumes wider than 10.21 µm(3) with 1.35 µm diameter were detected. Cul-de-sac-type voids (blind pores) and through-and-through voids (continuous pores) were discriminated. The apical thirds had a significantly lower 3D void volume (P < 0.05) than the middle and coronal thirds. The 3D void volume reduced significantly (P < 0.05) over time. ESEM-EDX analysis revealed that MTA Flow sealer created a dense apatite layer after 7 days of immersion in HBSS, whilst only sparse calcium phosphate deposits were detected on AH Plus even after 28 days. CONCLUSIONS: Micro-CT proved to be a powerful nondestructive 3D analysis tool for visualizing the porous internal microstructure of dental/endodontic materials at the interface with dentine. The proportion of voids was least in the apical third of root canals. Voids reduced over time in the presence of simulated body fluid.

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.

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 Hank's 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.

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 (Dulbecco's phosphate-buffered saline). Calcium and fluoride release and pH of the storage solution were measured. The results obtained were analysed statistically (Tukey's 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.

Evaluation of the radiopacity of calcium silicate cements containing different radiopacifiers.

AIM: To identify the suitable ratio of alternative radiopacifiers to impart the necessary radiopacity to calcium silicate cements (CSC) and assess the purity of the radiopacifying agents. METHODOLOGY: Alternative radiopacifying materials for incorporation into CSC included barium sulphate, titanium oxide, zinc oxide, gold powder and silver/tin alloy. The chemical composition of the alternative radipacifying materials and bismuth oxide, which is used in mineral trioxide aggregate (MTA), was determined using energy dispersive X-ray analysis. In addition, using an aluminium step-wedge and densitometer, the radiopacity of each material was evaluated as recommended by international standards. The optical density was compared with the relevant thickness of aluminium (Al). A commercial MTA and CSC were used as controls. Statistical analysis comparing the radiodensity of the different cements to MTA was performed using anova with P = 0.05 and post hoc Tukey test. RESULTS: All percentage replacements of bismuth oxide, gold and silver-tin alloy powder, and the 25% and 30% replacements with barium sulphate and zinc oxide had radiopacities greater than 3 mm thickness of aluminium (Al) recommended by ISO 6876 (2002). The 25% replacement of cement with gold powder and 20% replacement of cement with silver/tin alloy powder exhibited radiopacity values of 8.04 mm Al and 7.52 mm Al, respectively, similar to MTA (P > 0.05). The cement replaced with 20% bismuth oxide showed a radiopacity of 6.83 mm Al, lower than MTA (P = 0.003). CONCLUSIONS: Silver/tin alloy and gold powder imparted the necessary radiopacity to a calcium silicate-based cement. Barium sulphate was also a suitable radiopacifier together with a lower concentration of silver/tin alloy and gold powder that achieved the radiodensity recommended by ISO 6876. Further research is required to investigate the broader properties of the calcium silicate-based cement with the different radiopacifiers.

MTA and F-doped MTA cements used as sealers with warm gutta-percha. Long-term study of sealing ability.

AIM: To evaluate the long-term sealing ability (up to 6 months) of two experimental calcium silicate MTA cements used as root canal sealers in association with warm gutta-percha. METHODOLOGY: Calcium silicate (MTA) and calcium-fluoro-silicate powders were prepared. Sodium fluoride was included in FMTA (Fluoride-doped Mineral Trioxide Aggregate) as an expansive and retardant agent. Single-rooted teeth were instrumented with NiTi rotary instruments, filled with warm gutta-percha in association with one of the experimental sealers or with AH Plus as a control (n = 20 for each sealer) and stored at 37 °C. Sealing was assessed at 24, 48 h, 1, 2 weeks and 1, 3, 6 months by a fluid filtration method. Scanning electron microscopy with energy dispersive analysis (SEM/EDX) was used to study the dentine/sealer interface of roots stored for 6 months and the surface of cement disks stored for 24 h. RESULTS: All sealers revealed a statistically significant reduction (P < 0.05) in fluid filtration after the first 2 weeks. No statistically significant differences were observed between FMTA and AH Plus at all analysis times. At short times (24, 48-h), no statistically significant differences were found between the experimental cements and AH Plus. At long-term evaluations (1, 3, 6 months), FMTA and AH Plus sealed significantly better (P < 0.05) than MTA. FMTA was associated with lower fluid filtration rates, and the seal was stable from 48 h to 6 months, thus proving the most effective material. Scanning electron microscopy with energy dispersive analysis of root sections filled with calcium silicate sealers revealed the formation of a blend layer of gutta-percha and cement consequent to the warm gutta-percha condensation technique. Scanning electron microscopy with energy dispersive analysis of 24-h-stored disks identified a Ca-rich coating on the outer surface consisting of globular particles (calcium hydroxide and calcium carbonate), and a deeper internal Ca- and Si-rich region consisting of needle-like ettringite crystals and round formations of calcium silicate hydrate gel. CONCLUSION: Fluoride-doped MTA demonstrated stable sealing during a period of up to 6 months and significantly better than conventional calcium silicate MTA cements and comparable to AH Plus. The study supports the suitability of calcium silicate MTA cements as sealers in association with warm gutta-percha for root filling.

Apatite-forming ability (bioactivity) of ProRoot MTA.

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.

The effect of ultrasonic removal of various root-end filling materials.

AIM: To compare residual root-end filling material in apical root-end cavities following their removal with ultrasonic retrotips. METHODOLOGY: Thirty single-rooted teeth were filled with Thermafil and AH Plus sealer. Root-ends were resected at 90 degrees, 3 mm from the apex. Root-end cavities were prepared with diamond burs and ultrasonic retrotips and filled with one of three filling materials: group I: Retro-TC (calcium silicate-based cement), group II: IRM (Dentsply, Germany), group III: Vitrebond (3M ESPE, USA). After 30 days of storage, ultrasonic retrotips were used to remove materials from the root-end cavities. The ultrasonic application time was fixed at 60 s. Polyether impressions and replicas of the root-ends were made. Root apices and replicas were examined by one operator under a scanning electron microscope. Remnants of residual materials were evaluated using a four-level scoring system; fractures, smear layer and exposed dentinal tubules were also examined. RESULTS: Forty per cent of the specimens filled with Retro-TC revealed complete removal of the material with exposure of dentinal tubules, whilst 60% contained residual cement. Twenty per cent of specimens filled with IRM were completely devoid of material, whereas 80% had retained material. Ten per cent of specimens filled with Vitrebond retained a moderate amount of material whilst 90% had substantial retention of the material. Statistically significant differences were found (P < 0.05) amongst the three groups of materials. CONCLUSIONS: Retro-TC was successfully removed in 40% of cases using ultrasonics retrotips for 60 s, whereas IRM and Vitrebond specimens had evidence of retained material in 80% and 90% of all specimens respectively.