Publications by authors named "Josette Camilleri"

75 Publications

Physicochemical Properties and Dentin Bond Strength of a Tricalcium Silicate-Based Retrograde Material.

Braz Dent J 2017 Jan-Feb;28(1):51-56

Department of Restorative Dentistry, Araraquara Dental School, UNESP - Universidade Estadual Paulista, Araraquara, SP, Brazil.

The aim of this study was to evaluate the physicochemical properties and the apical dentin bond strength of the tricalcium silicate-based Biodentine in comparison to white MTA and zinc oxide eugenol-based cement (ZOE). Setting time and radiopacity were evaluated according to ISO 6876:2012 specification. Final setting time, compressive strength and pH were also assessed. Material's bond strength to the apical root canal dentin was measured by the push-out assay. Data were analyzed by ANOVA and Tukey-Krammer post-hoc test. Biodentine presented the shortest initial (16.2±1.48 min) and final setting time (35.4±5.55 min). Radiopacity of Biodentine (2.79±0.27 mmAl) does not agree with ISO 6876:2012 specifications. On the other hand, Biodentine showed higher compressive strength after 21 days (37.22±5.27 MPa) and higher dentin bond strength (11.2±2.16 MPa) in comparison to white MTA (27.68±3.56 MPa for compressive strength and 2.98±0.64 MPa for bond strength) (p<0.05). Both MTA and Biodentine produced an alkaline environment (approximately pH 10) (p>0.05) compared to ZOE (pH 7). It may be concluded that Biodentine exhibited faster setting, higher long-term compressive strength and bond strength to the apical dentin than MTA and ZOE.
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http://dx.doi.org/10.1590/0103-6440201701135DOI Listing
January 2018

Why Biphasic? Assessment of the Effect on Cell Proliferation and Expression.

J Endod 2017 May 11;43(5):751-759. Epub 2017 Mar 11.

Department of Restorative Dentistry, Faculty of Dental Surgery, University of Msida, Malta. Electronic address:

Introduction: Tricalcium silicate (TCS)-based materials are used in endodontics because they are hydraulic and interact with blood, tissue fluids, and phosphate-based root canal irrigants, resulting in biomineralization. Newer-generation materials are biphasic; calcium phosphate is added to the TCS; thus, the material has 2 cementitious phases. The effect of this addition is not known; thus, the aim of this study was to characterize biphasic cements and assess cellular proliferation and expression.

Methods: TCS cement mixed with calcium phosphate monobasic or hydroxyapatite in 1:1 proportion was prepared. The powders and the mixed cements soaked in Hank's balanced salt solution for 28 days were characterized by scanning electron microscopy (SEM), energy-dispersive spectroscopy, and X-ray diffraction analysis. Ion leaching was investigated using inductively coupled plasma mass spectroscopy. Cellular interaction with material leachate was investigated by exposing human primary osteoblasts to the leachate from the cements. Cell growth and proliferation were determined using methyltetrazolium assay and SEM.

Results: The addition of a calcium phosphate phase to tricalcium silicate changed the material hydration with a reduction in pH and calcium ion release in the leachate when calcium phosphate monobasic was added. No crystalline calcium hydroxide was formed for both biphasic materials. The biphasic cements exhibited a reduction in cell growth and proliferation. SEM of the materials showed heavy carbonation of the material surface caused by processing for microscopy.

Conclusions: The addition of a second cementitious phase results in modification of the hydration characteristics of TCS cement with deterioration of material and biocompatibility properties.
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http://dx.doi.org/10.1016/j.joen.2016.12.022DOI Listing
May 2017

Clinical relevance of antimicrobial testing results for dental restorative materials.

J Appl Biomater Funct Mater 2017 Apr 26;15(2):e153-e161. Epub 2017 Apr 26.

Department of Restorative Dentistry, Faculty of Dental Surgery, University of Malta, Msida - Malta.

Background: The antimicrobial activity of restorative materials is clinically relevant because all dental materials are subject to an environment containing bacteria. This study aimed to investigate the use of 2 methodologies referred to in the literature to assess antimicrobial properties of restorative materials and investigate whether material properties alter results of these traditional methodologies.

Methods: A number of dental restorative materials - namely, Chemfil Superior®, Spectrum®, Heliobond®, Ionoseal®, Dyract Extra®, Smart Dentin Replacement (SDR®) and Biodentine® - were characterized by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD) analysis, Fourier transform infrared (FT-IR) spectroscopy and pH analysis. Antimicrobial activity was assessed using agar diffusion and biofilm accumulation tests. Key factors affecting results were assessed using analysis of covariance.

Results: Biodentine after immediate mixing and Ionoseal aged for 6 weeks resulted in an inhibition zone, while significantly higher McFarland readings were observed in the presence of barium when using materials Ionoseal, Dyract and SDR at 24-hour aging. Through analysis of covariance it was shown that material properties affected methodology results.

Conclusions: Properties of materials affect results of antimicrobial testing, but this may not directly reflect the antimicrobial potential of the material in question. Careful choice of methodology and interpretation of results is important.
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http://dx.doi.org/10.5301/jabfm.5000337DOI Listing
April 2017

Effect of polishing procedures and hydrothermal aging on wear characteristics and phase transformation of zirconium dioxide.

J Prosthet Dent 2017 Apr 27;117(4):545-551. Epub 2016 Oct 27.

Associate Professor, Department of Restorative Dentistry, Faculty of Dental Surgery, University of Malta, Malta. Electronic address:

Statement Of Problem: Yttria-stabilized zirconia used for the fabrication of crowns and fixed prostheses may require intraoral adjustments after placement and cementation. Grinding and polishing methods may result in changes in the surface characteristics of zirconia.

Purpose: The purpose of this in vitro study was to assess the effect of polishing procedures on surface roughness, topographical and phase changes of zirconia, and wear of the opposing dentition.

Material And Methods: Presintered and precut yttria-stabilized zirconia specimens (10×10×1 mm) were divided into 4 groups (control, Intensiv, Shofu, 3M ESPE) depending on the polishing method used to prepare the specimens. All tests were carried out in triplicate. The specimens were polished depending on the polishing regimen, while the control was left untreated. The specimens were thermocycled for 3000 cycles, with a temperature range of 5°C to 55°C. The surface roughness, elemental, and phase changes caused by polishing before and after thermocycling were assessed with surface profilometry, energy-dispersive spectroscopy, and x-ray diffraction analysis. The wear on antagonist steatite balls was also measured after mastication simulation. Statistical analysis was performed using 1-way ANOVA and the Tukey post hoc test to perform multiple comparison tests (α=.05).

Results: The polishing procedures increased surface roughness (Ra) of yttria-stabilized zirconia from 0.52 for the control specimen to 0.73 for Intensiv, 0.70 for Shofu, and 0.70 for 3M ESPE (P<.05), which was reduced by thermocycling to 0.44 (control), 0.58 (Intensiv), and 0.58 (Shofu) (P<.001), while roughness remained unchanged for 3M ESPE specimens (0.75; P=.452). The deposition of aluminum when using Shofu abrasives and nickel in Intensiv was demonstrated. Phase changes were observed on the zirconia surface with formation of the monoclinic phase in all polishing methods. Specimen aging enhanced the surface phase changes and also induced compressive stresses in zirconia polished with Intensiv. The different polishing protocols did not affect the wear to the antagonist (P>.05).

Conclusions: Polishing zirconia increased surface roughness and led to surface phase changes, but wear to the antagonist was not affected.
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http://dx.doi.org/10.1016/j.prosdent.2016.09.004DOI Listing
April 2017

Model assessing thermal changes during high temperature root canal irrigation.

Healthc Technol Lett 2016 Sep 5;3(3):247-251. Epub 2016 Aug 5.

Department of Mechanical Engineering, Faculty of Engineering , University of Malta , Msida , Malta.

The main aim of root canal irrigation is to eliminate micro-organisms. Sodium hypochlorite (NaOCl) is considered to be the ideal material and raising its temperature potentiates the antimicrobial activity. NaOCl may lead to localised tissue necrosis when extruded past the root apex. This study analyses the use of high temperature root canal irrigation as an alternative process for the elimination of microorganisms from the root canal system. An experimental set-up was designed where a constant supply of heat was passed from a heat source through a copper wire inside the root canal. The data acquired together with known constants pertaining to enamel and dentine was used to numerically model the thermal changes in a tooth using a finite element method. Results obtained from the finite element thermal model of the tooth were repeatable and were validated with the experimental results. The thermo-physical properties of the tooth were varied and convergence criteria met. The temperatures reached were below what has been reported to cause irreversible damage to the bone. This was further confirmed from a series of simulations that were undertaken. The temperatures achieved were suitable for the elimination of microorganisms during root canal therapy.
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http://dx.doi.org/10.1049/htl.2016.0008DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5047292PMC
September 2016

Characterization and angiogenic potential of xenogeneic bone grafting materials: Role of periodontal ligament cells.

Dent Mater J 2016 Dec 29;35(6):900-907. Epub 2016 Sep 29.

Aix Marseille Univ, CNRS, ISM, Inst Movement Sci.

Adequate revascularization is a prerequisite for successful healing of periodontal bone defects. This study characterized three different xenogeneic bone grafting materials: Gen-Os of equine and porcine origins, and anorganic Bio-Oss. We also investigated their angiogenic potential. All materials were composed of poorly crystalline calcium oxide phosphate, with Bio-Oss exhibiting a carbonated phase and larger particle size and both Gen-Os showing the presence of collagen. Both Gen-Os materials significantly enhanced vascular endothelial growth factor (VEGF) secretion by PDL cells. A significant increase in endothelial cell proliferation was observed in cultures with both Gen-Os conditioned media, but not with that of Bio-Oss. Finally, angiogenesis was stimulated by both Gen-Os conditioned media as demonstrated by an increased formation of capillary-like structures. Taken together, these findings indicate an enhanced angiogenic potential of both Gen-Os bone grafting materials when applied on PDL cells, most likely by increasing VEGF production.
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http://dx.doi.org/10.4012/dmj.2016-005DOI Listing
December 2016

Properties of Tricalcium Silicate Sealers.

J Endod 2016 Oct 11;42(10):1529-35. Epub 2016 Aug 11.

Department of Restorative Dentistry, Faculty of Dental Surgery, University of Malta, Msida, Malta.

Introduction: Sealers based on tricalcium silicate cement aim at an interaction of the sealer with the root canal wall, alkalinity with potential antimicrobial activity, and the ability to set in a wet field. The aim of this study was to characterize and investigate the properties of a new tricalcium silicate-based sealer and verify its compliance to ISO 6876 (2012).

Methods: A new tricalcium silicate-based sealer (Bio MM; St Joseph University, Beirut, Lebanon), BioRoot RCS (Septodont, St Maure de Fosses, France), and AH Plus (Dentsply, DeTrey, Konstanz, Germany) were investigated. Characterization using scanning electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction analysis was performed. Furthermore, sealer setting time, flow, film thickness, and radiopacity were performed following ISO specifications. pH and ion leaching in solution were assessed by pH analysis and inductively coupled plasma.

Results: Bio MM and BioRoot RCS were both composed of tricalcium silicate and tantalum oxide in Bio MM and zirconium oxide in BioRoot RCS. In addition, the Bio MM contained calcium carbonate and a phosphate phase. The inorganic components of AH Plus were calcium tungstate and zirconium oxide. AH Plus complied with the ISO norms for both flow and film thickness. BioRoot RCS and Bio MM exhibited a lower flow and a higher film thickness than that specified for sealer cements in ISO 6876. All test sealers exhibited adequate radiopacity.

Conclusions: Bio MM interacted with physiologic solution, thus showing potential for bioactivity. Sealer properties were acceptable and comparable with other sealers available clinically.
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http://dx.doi.org/10.1016/j.joen.2016.06.002DOI Listing
October 2016

Effect of polishing instruments and polishing regimens on surface topography and phase transformation of monolithic zirconia: An evaluation with XPS and XRD analysis.

J Mech Behav Biomed Mater 2016 12 28;64:104-12. Epub 2016 Jul 28.

University of Zürich, Dental Materials Unit, Center for Dental and Oral Medicine, Clinic for Fixed and Removable Prosthodontics and Dental Materials Science, Plattenstrasse 11, CH-8032 Zurich, Switzerland.

Purpose: Polishing procedures might alter monolithic zirconia (MZ) surface resulting in phase changes that can be deleterious for clinical performance and antagonist tooth wear. This study investigated the topographical features and phase transformation in MZ after polishing with different regimens simulating the clinical workflow. ​

Materials And Methods: MZ specimens (Katana Zirconia HT, Kuraray-Noritake) (12×12×1.8 mm(3)) were grinded and polished using one of the five systems assessed: BG: Silicone carbide polishers (Brownie, Greenie, Super Greenie); CG: Diamond impregnated ceramic polisher kit (Ceragloss); EV: Synthetically bonded grinder interspersed with diamond (EVE Kit); SL: Urethane coated paper with aluminium oxide grits (Soflex Finishing and Polishing System Kit) and DB: Diamond bur (8 µm). Polished specimens were initially roughened with 220 µm diamond burs (Grinding Bur-GB) (10 s, 160.000160,000 rpm) and considered for baseline measurements. Polishing regimens were performed for 10 s using a slow-speed hand piece under water-cooling except for SL, in a custom made device (750 g; 5000 and 75,000 rpm). Surface roughnesses, phase changes (XRD) were assessed, surface characterization was performed (SEM, EDS).

Results: The highest roughness was obtained with the EV system (1.11 µm) compared to those of other systems (0.13-0.4 µm) (pθ and minor peak at 34.94°2θ. While GB, CG, EV, SL and DB exhibited a peak shift to the left, BG demonstrated a right peak shift on the 2θ scale. Monoclinic phase change was not noted in any of the groups.

Conclusion: All polishing methods, except BG, exhibited a peak shift towards the lower angles of the 2-theta scale. Since the peak shifts were in the order of fractions of an angle they are attributed to stress formation rather than a phase change in the material. Thus, all polishing systems tested may not be detrimental for the phase transformation of MZ. EV system resulted in the highest roughness and none of the polishing regimens restored the polishability to the baseline level.
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http://dx.doi.org/10.1016/j.jmbbm.2016.07.025DOI Listing
December 2016

Investigation of Acrylic Resin Disinfection Using Chemicals and Ultrasound.

J Prosthodont 2018 Jun 31;27(5):461-468. Epub 2016 May 31.

Department of Restorative Dentistry, Faculty of Dental Surgery, University of Malta, Malta.

Purpose: Dental prosthetic and orthodontic appliances are transported from the clinic to the laboratory for additions and repairs. These appliances, containing microbes from the oral flora, are a high risk for cross-contamination. The aim of this study was to evaluate the effect of chemical and ultrasound disinfection against two in vitro biofilms and an in vivo formed biofilm grown on unprepared and polished polymethyl methacrylate (PMMA) surfaces.

Materials And Methods: Rough and polished self-curing PMMA surfaces were infected with strains of both Candida albicans and Streptococcus oralis. After incubation, the samples were treated with different disinfection methods, including ultrasound treatment for both 15 and 30 seconds, and immersion in glutaraldehyde and alcohol-based chemical disinfectants (MD520 and Minuten, respectively). The disinfecting efficacy was assessed by colony forming units (CFU) analysis and by scanning electron microscopy (SEM). Furthermore the adequacy of bacterial elimination of application of 30-second ultrasound and MD520 was assessed on PMMA retrieved from ten volunteers by CFU analyses. ANOVA with p = 0.05 followed by the Tukey post hoc test and the Student t-test was used to analyze the data.

Results: The ultrasound treatment for 30 seconds, MD520, and Minuten were the most effective disinfectant methods as they reduced the microbial counts compared to the control (p < 0.05) as shown in the in vitro analyses. S. oralis adhered more to rough acrylic resin surfaces (p < 0.05). Ultrasound treatment was the most effective way to reduce microbial counts on PMMA exposed to oral flora (p = 0.043).

Conclusion: Ultrasound treatment for 30 seconds was effective against C. albicans, S. oralis, and the oral flora as shown by testing microbial growth on agar plates and SEM.
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http://dx.doi.org/10.1111/jopr.12511DOI Listing
June 2018

Surface Microstructural Changes and Release of Ions from Dental Metal Alloy Removable Prostheses in Patients Suffering from Acid Reflux.

J Prosthodont 2018 Feb 31;27(2):115-119. Epub 2016 May 31.

Department of Restorative Dentistry, Faculty of Dental Surgery, University of Malta, Msida, Malta.

Purpose: To investigate the surface microstructural changes and the release of ions from metal alloys used in removable dental prostheses and the potential effects of acidic reflux found in patients suffering from gastroesophageal reflux disease (GERD).

Materials And Methods: Thirty-seven (37) patients were recruited. Data were gathered through a questionnaire and clinical examination. Samples of metal alloy from the dentures and patient's saliva were collected. GERD was confirmed using the GerdQ questionnaire. Denture samples were characterized using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), while salivary samples were tested for trace metal ions using inductively coupled plasma (ICP).

Results: Characterization of denture samples revealed the presence of nickel, cobalt, and chromium. Nickel-chromium exhibited an etched surface appearance, while cobalt-chromium exhibited no noticeable surface microstructural changes. Higher mean salivary levels of chromium and cobalt in patients wearing any metal alloy-based denture and of chromium and nickel in patients wearing Ni-Cr prostheses were found to be significant. No differences were found in salivary metal ion levels of patients suffering from GERD.

Conclusions: Nickel-chromium alloy is prone to acid etching in the oral cavity, while cobalt-chromium alloy appears to be more resistant. Cobalt, chromium, and nickel are leached in saliva of patients using cast removable prostheses. The impact of gastric acid on metal ion release from dental metal alloys deserves further investigations.

Clinical Significance: This preliminary study suggests that metal-based removable prostheses leach trace metal ions in saliva. Nickel-chromium-based dentures exhibit an etched appearance unrelated to GERD.
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http://dx.doi.org/10.1111/jopr.12470DOI Listing
February 2018

Bioactivity Potential of EndoSequence BC RRM Putty.

J Endod 2016 Apr 16;42(4):615-21. Epub 2016 Jan 16.

Department of Restorative Dentistry, Faculty of Dental Surgery, University of Malta, Malta. Electronic address:

Introduction: The aim of this study was to characterize and assess the interaction of EndoSequence BC RRM putty (Brasseler USA, Savannah, GA) in contact with blood and simulated body fluid. Tricalcium silicate-based materials are in contact with blood and tissue fluids during and after their setting. These materials are hydraulic; thus, their properties improve in moist conditions. However, specific environmental conditions may modify the material setting.

Methods: EndoSequence BC RRM putty was characterized by scanning electron microscopy, energy dispersive spectroscopy, and X-ray diffraction analysis. This was done before setting and after contact with water, Hank's balanced salt solution, and heparinized whole blood. Furthermore, characterization of an explanted material from a failed root-end surgery was performed.

Results: The EndoSequence BC RRM putty was composed of tricalcium silicate, tantalum oxide, and zirconium oxide. The tricalcium silicate reaction led to the formation of calcium hydroxide, and this was evident over the putty in contact with water and Hank's balanced salt solution. In the latter case, there was also the formation of globular crystals synonymous with hydroxyapatite formation. The material in contact with blood exhibited a poorly crystalline surface with additional peaks for calcium, phosphorus, and chlorine, whereas the material retrieved from the failed root-end surgery had deposition of calcium carbonate on its surface.

Conclusions: The environmental conditions affect the hydration of the EndoSequence RMM putty and consequentially the material interaction with the environment. However, in vitro material assessment may not be representative of the clinical situation because carbon dioxide present in vivo leads to the formation of calcium carbonate rather than the hydroxyapatite reported in in vitro studies.
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http://dx.doi.org/10.1016/j.joen.2015.12.004DOI Listing
April 2016

Effectiveness of Disinfectants on Antimicrobial and Physical Properties of Dental Impression Materials.

Int J Prosthodont 2016 Jan-Feb;29(1):63-7

Purpose: The aim of this study was to assess the antimicrobial activity of chemical disinfectants on alginate and silicone impression materials. The effect of chemical disinfectants on the dimensional stability of the impression materials was also assessed.

Materials And Methods: For the microbiologic assessment, impressions of the maxillary arch were taken from 14 participants, 7 using alginate and 7 using an addition silicone. The impressions were divided into three sections. Each section was subjected to spraying with MD 520 or Minuten or no disinfection (control), respectively. Antimicrobial action of the chemical disinfectants was assessed by measuring microbial counts in trypticase soy agar (TSA) media and expressing the results in colony-forming units/cm2. The surface area of the dental impressions was calculated by scanning a stone cast using computer-aided design/computer-assisted manufacture and analyzing the data using a custom computer program. The dimensional stability of the impression materials after immersion in disinfectants was assessed by measuring the linear displacement of horizontally restrained materials using a traveling microscope. The percent change in length over 3 hours was thus determined.

Results: Alginate exhibited a higher microbial count than silicone. MD 520 eliminated all microbes as opposed to Minuten. The bacterial growth after Minuten disinfection was almost twice as much for alginate than for addition silicone impressions. The chemical disinfectants affected the alginate dimensional stability. Minuten reduced the shrinkage sustained by alginate during the first hour of storage.

Conclusions: Alginate harbors three times more microorganisms than silicone impression material. Chemical disinfection by glutaraldehyde-based disinfectant was effective in eliminating all microbial forms for both alginate and silicone without modifying the dimensional stability. Alcohol-based disinfectants, however, reduced the alginate shrinkage during the first 90 minutes of setting. The current studies also propose another method to report the surface area based on accurate estimation by 3D image analysis.
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http://dx.doi.org/10.11607/ijp.4358DOI Listing
April 2016

Calcium silicate-based sealers: Assessment of physicochemical properties, porosity and hydration.

Dent Mater 2016 Feb 22;32(2):e30-40. Epub 2015 Dec 22.

Department of Restorative Dentistry, Faculty of Dental Surgery, University of Malta, Malta.

Objectives: Investigation of hydration, chemical, physical properties and porosity of experimental calcium silicate-based sealers.

Methods: Experimental calcium silicate-based sealers with calcium tungstate and zirconium oxide radio-opacifiers were prepared by mixing 1g of powder to 0.3 mL of 80% distilled water and 20% propylene glycol. MTA and MTA Fillapex were used as controls. The raw materials and set sealers were characterized using a combination of scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. Physical properties were analyzed according to ANSI/ADA. The pH and calcium ion release were assessed after 3, 24, 72 and 168 h. The porosity was assessed using mercury intrusion porosimetry.

Results: The analysis of hydration of prototype sealers revealed calcium hydroxide as a by-product resulting in alkaline pH and detection of calcium ion release, with high values in initial periods. The radiopacity was similar to MTA for the sealers containing high amounts of radio-opacifiers (p>0.05). Flowability was higher and film thickness was lower for resinous MTA Fillapex sealer (p<0.05). The test sealers showed water sorption and porosity similar to MTA (p>0.05).

Significance: The prototype sealers presented adequate hydration, elevated pH and calcium ion release. Regarding physical properties, elevated proportions of radio-opacifiers were necessary to accomplish adequate radiopacity, enhance flowability and reduce film thickness. All the tested sealers presented water sorption and porosity similar to MTA.
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http://dx.doi.org/10.1016/j.dental.2015.11.008DOI Listing
February 2016

Physical and Chemical Properties and Subcutaneous Implantation of Mineral Trioxide Aggregate Mixed with Propylene Glycol.

J Endod 2016 Mar 22;42(3):474-9. Epub 2015 Dec 22.

Department of Dentistry, Dental School of Bauru, University of São Paulo-USP, Bauru, São Paulo, Brazil.

Introduction: The aim of this study was to evaluate the physical, chemical, and biological properties of mineral trioxide aggregate (MTA) mixed with 80% distilled water and 20% propylene glycol (PG) compared with MTA mixed with distilled water only.

Methods: Flowability, film thickness, and solubility were analyzed according to American National Standards Institute/American Dental Association specification 57/2000. Initial and final setting times were assessed according to American Society for Testing and Materials specification C266/08. Porosity was assessed by using mercury intrusion porosimetry after 1 and 28 days of hydration, and the pH and calcium ion release were assessed after 3, 24, 72, and 168 hours. For the tissue reaction, the cements were implanted in 24 albino rats (2 groups, n = 12). An analysis of the inflammatory infiltrate was performed after 15, 30, and 60 days.

Results: MTA + PG exhibited lower film thickness and higher final setting time. No differences were verified for flowability (P > .05). MTA + PG showed high porosity at 1 day of hydration (P < .05). All the test cements demonstrated an alkaline pH. Microscopic analysis of the specimens revealed neoformation of connective tissue in contact with the cements.

Conclusions: The introduction of PG as a mixing vehicle alters the physical and chemical properties of MTA and is biologically acceptable.
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http://dx.doi.org/10.1016/j.joen.2015.10.014DOI Listing
March 2016

Development of novel tricalcium silicate-based endodontic cements with sintered radiopacifier phase.

Clin Oral Investig 2016 Jun 1;20(5):967-82. Epub 2015 Sep 1.

Department of Restorative Dentistry, Faculty of Dental Surgery, Mater Dei Hospital, University of Malta Medical School, Msida, MSD 2090, Malta.

Objectives: All implants, bone and endodontic cements need to be sufficiently radiopaque to be able to be distinguished from neighbouring anatomical structures post-operatively. For this purpose, radiopacifying materials are added to the cements to render them sufficiently radiopaque. Bismuth oxide has been quite a popular choice of radiopacifier in endodontic materials. It has been shown to cause dental discoloration. The aim of this study was to develop, characterize and assess the properties of tricalcium silicate cement with alternative radiopacifiers, which are either inter-ground or sintered to the tricalcium silicate cement.

Methods: Custom-made endodontic cements based on tricalcium silicate and 20 % barium, calcium or strontium zirconate, which were either inter-ground or sintered at high temperatures, were produced. The set materials stored for 28 days in Hank's balanced salt solution were characterized by scanning electron microscopy and X-ray diffraction analysis. Assessment of pH, leaching, interaction with physiological solution, radiopacity, setting time, compressive strength and material porosity were investigated. Mineral trioxide aggregate (MTA) Angelus was used as control.

Results: Addition of radiopacifying materials improved the radiopacity of the material. The sintered cements exhibited the formation of calcium zirconate together with the respective radiopacifier phase. All materials produced calcium hydroxide on hydration, which interacted with tissue fluids forming hydroxyapatite on the material surface. The physical properties of the tricalcium silicate-based cements were comparable to MTA Angelus.

Conclusions: A novel method of producing radiopaque tricalcium silicate-based cements was demonstrated. The novel materials exhibited properties, which were either comparable or else improved over the control.

Clinical Relevance: The novel materials can be used to replace MTA for root-end filling, perforation repair and other clinical applications where MTA is indicated.
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http://dx.doi.org/10.1007/s00784-015-1578-1DOI Listing
June 2016

Dental discoloration caused by bismuth oxide in MTA in the presence of sodium hypochlorite.

Clin Oral Investig 2015 Dec 30;19(9):2201-9. Epub 2015 Apr 30.

Department of Restorative Dentistry, Faculty of Dental Surgery, Medical School, University of Malta, Msida, MSD 2090, Malta.

Objectives: The aim of this research was to analyse the dental discolouration caused by mineral trioxide aggregate (MTA) induced by bismuth oxide and also assess the colour stability of other dental cements.

Materials And Methods: Bismuth oxide, calcium tungstate and zirconium oxide were placed in contact with sodium hypochlorite for 24 h after which they were dried and photographed. Phase analyses were performed by X-ray diffraction (XRD) of radiopacifiers before and after immersion in sodium hypochlorite. Furthermore, teeth previously immersed in water or sodium hypochlorite were filled with MTA Angelus, Portland cement (PC), PC with 20 % zirconium oxide, PC with 20 % calcium tungstate and Biodentine. Teeth were immersed for 28 days in Hank's balanced salt solution after which they were sectioned and characterized using scanning electron microscopy (SEM) with energy-dispersive mapping and stereomicroscopy.

Results: Bismuth oxide in contact with sodium hypochlorite exhibited a change in colour from light yellow to dark brown. XRD analysis demonstrated peaks for radiopacifier and sodium chloride in samples immersed in sodium hypochlorite. The SEM images of the dentine to material interface showed alteration in material microstructure for MTA Angelus and Biodentine with depletion in calcium content in the material. The energy-dispersive maps showed migration of radiopacifier and silicon in dentine.

Conclusions: MTA Angelus in contact with a tooth previously immersed in sodium hypochlorite resulted in colour alteration at the cement/dentine interface.

Clinical Relevance: MTA Angelus should not be used after irrigation with sodium hypochlorite as this will result in tooth discoloration.
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http://dx.doi.org/10.1007/s00784-015-1466-8DOI Listing
December 2015

Effect of sterilization techniques prior to antimicrobial testing on physical properties of dental restorative materials.

J Dent 2015 Jun 22;43(6):703-14. Epub 2015 Apr 22.

Department of Restorative Dentistry, Faculty of Dental Surgery, University of Malta, Malta. Electronic address:

Objectives: The aim of this study was to investigate any changes to the microstructure and surface properties of selected dental materials after sterilization carried out prior to subjecting them to antimicrobial testing. Initial microbial contamination on the material, as well as other possible sources of contamination were also assessed.

Methods: The materials investigated included dentine replacement materials Chemfil Superior(®), Ionoseal(®), Dyract Extra(®) and SDR(®). The materials were characterized by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The test materials were sterilized using alcohol, steam, ultraviolet light (UV) and ethylene oxide and any changes to these materials were then assessed by SEM, microhardness testing and Fourier transform infrared (FT-IR) spectroscopy. Material microbial levels before treatments were assessed by plate counting technique and turbidity tests. Possible contamination through dispensers was assessed by analysing the CFU/sample.

Results: Ethylene oxide affected the microstructure of the Chemfil, Ionoseal and Dyract, resulting in flattening of the SiO stretching vibrations and deposition of chlorine and calcium respectively in Chemfil and Dyract. Varied contamination was demonstrated on all materials when incubated in anaerobic conditions.

Conclusions: The different sterilization techniques affected the microstructure of the materials under investigation. Samples of materials produced in sterile conditions could also be contaminated with bacteria, either from the material itself or through the dispensing apparatus.

Clinical Significance: Results of antimicrobial studies cannot be extrapolated clinically as the material sterilization treatment results in changes to material chemistry and microstructure, which could in turn affect the materials' antimicrobial activity.
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http://dx.doi.org/10.1016/j.jdent.2015.03.012DOI Listing
June 2015

Staining Potential of Neo MTA Plus, MTA Plus, and Biodentine Used for Pulpotomy Procedures.

J Endod 2015 Jul 15;41(7):1139-45. Epub 2015 Apr 15.

Department of Restorative Dentistry, Faculty of Dental Surgery, University of Malta, Malta. Electronic address:

Introduction: Mineral trioxide aggregate (MTA) used for pulpotomy procedures in immature permanent teeth can reduce treatment to 1 session as opposed to classic calcium hydroxide therapy, which necessitates multiple appointments. The main disadvantage of MTA use is crown discoloration after treatment. The aim of this study was to characterize 3 materials that are used for pulpotomy procedures in immature permanent teeth and assess their color stability in the presence of sodium hypochlorite solution.

Methods: Hydrated Neo MTA Plus (Avalon Biomed Inc, Bradenton, FL), MTA Plus (Avalon Biomed Inc), and Biodentine (Septodont, Saint-Maur-des-Fossés, France) were characterized after immersion in Hank's balanced salt solution for 1 day and 28 days using a combination of scanning electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction analysis. The color stability of the 3 materials in contact with water or sodium hypochlorite was evaluated by photography, spectrophotometry, and X-ray diffraction analysis.

Results: All the materials hydrated and produced calcium hydroxide as a by-product of hydration at early age. All materials interacted with synthetic tissue fluid, forming a calcium phosphate phase. MTA Plus exhibited discoloration in contact with sodium hypochlorite.

Conclusions: All the materials tested are suitable to be used in the treatment of immature teeth because they all produced calcium hydroxide, which is necessary to induce dentin bridge formation and continued root formation. Neo MTA Plus and Biodentine are suitable alternatives to MTA, and they do not exhibit discoloration.
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http://dx.doi.org/10.1016/j.joen.2015.02.032DOI Listing
July 2015

Color stability, radiopacity, and chemical characteristics of white mineral trioxide aggregate associated with 2 different vehicles in contact with blood.

J Endod 2015 Jun 19;41(6):947-52. Epub 2015 Mar 19.

Department of Operative Dentistry, Endodontics and Dental Materials, Bauru School of Dentistry, University of São Paulo, Bauru, São Paulo, Brazil.

Introduction: Discoloration of mineral trioxide aggregate (MTA) can be exacerbated by the interaction of the cement with body fluids such as blood. This study aimed to analyze the color alteration, chemical characteristics, and radiopacity of MTA manipulated with 2 different vehicles after immersion in blood or distilled water (DW).

Methods: MTA mixed with 100% DW or 80% DW/20% propylene glycol (PG) as vehicles were placed into rubber rings and incubated at 37°C and 100% relative humidity until set. Color assessment and scanning electron microscopy/energy-dispersive spectroscopy analysis were performed after setting and repeated after 7, 15, and 30 days after immersion in blood and DW. Statistical analysis for color alteration and radiopacity was performed using nonparametric Kruskal-Wallis and Dunn tests (P < .05).

Results: When 80% DW/20% PG was used as the vehicle, significantly lower color alterations were observed for all time periods compared with 100% DW when immersed in blood (P < .05). All surfaces displayed morphologic changes after immersion in both media because of loss of bismuth. A decrease in radiopacity was observed over time in all groups, with a statistically significant difference after 30 days for groups DW immersed in blood and 80% DW/20% immersed in both media (P < .05).

Conclusions: The ratio of 80% DW/20% PG as a vehicle for MTA results in a lower color alteration when in contact with blood.
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http://dx.doi.org/10.1016/j.joen.2015.02.008DOI Listing
June 2015

Systematic review of current dental implant coating materials and novel coating techniques.

Int J Prosthodont 2015 Jan-Feb;28(1):51-9

Purpose: Titanium dental implants have a high success rate; however, there are instances when a modified surface may be desirable. The aim of this article was to systematically review the different types of implant coatings that have been studied clinically, in vivo and in vitro, and the coating techniques being implemented.

Materials And Methods: The literature was searched electronically and manually through The Cochrane Library, Medline, and PubMed databases to identify articles studying dental implant surfaces and coating techniques. The database search strategy revealed 320 articles, of which 52 articles were considered eligible--40 in relation to implant coatings and 12 to the coating technique. An additional 30 articles were retrieved by hand search.

Results: Several materials were identified as possible candidates for dental implant coatings; these include carbon, bisphosphonates, bone stimulating factors, bioactive glass and bioactive ceramics, fluoride, hydroxyapatite (HA) and calcium phosphate, and titanium/titanium nitride. HA coatings still remain the most biocompatible coatings even though the more innovative bioglass suggests promising results. The most common coating techniques are plasma spraying and hydrocoating. More recent techniques such as the nanoscale technology are also discussed.

Conclusions: Several implant coatings have been proposed, and some appear to give better clinical results and improved properties than others. Clinical trials are still required to provide compelling evidence-based results for their long-term successful outcomes.
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http://dx.doi.org/10.11607/ijp.4124DOI Listing
March 2015

Antimicrobial properties of conventional restorative filling materials and advances in antimicrobial properties of composite resins and glass ionomer cements-A literature review.

Dent Mater 2015 Apr 10;31(4):e89-99. Epub 2015 Jan 10.

Department of Restorative Dentistry, Faculty of Dental Surgery, University of Malta, MSD 2090 Msida, Malta. Electronic address:

Objectives: It has been reported that complete caries removal from cavities during restoration of teeth is difficult. Furthermore with the tissue saving approach it is expected that more of the saved affected tissue will possibly harbor more residual bacteria. Antimicrobial restorative filling materials would be ideal to prevent the spread of caries after completion of tooth restoration, thus preventing recurrent decay and eventually restoration failure. This paper reviews the literature on the antimicrobial properties of dental restorative filling materials.

Methods: Pubmed searches on the antibacterial properties of restorative materials were carried out. Keywords were chosen to assess antibacterial properties of conventional filling materials. Methods of introducing antimicrobial agents in restorative materials were also reviewed together with the methodology used to assess antimicrobial activity.

Results: 174 articles from 1983 till 2014 were included.

Significance: Adhesive materials have decreased antimicrobial activity when compared to amalgams and zinc oxides. Several techniques have been employed in order to increase the antimicrobial activity of restorative materials. Although antimicrobial activity of restorative materials is important, the introduction of antimicrobial agents/techniques should not be at the expense of other material properties. Environmental changes within a material may affect the bacterial response to the antimicrobial. Bacterial adhesion to the restorative materials should be assessed. Long term assessment of antimicrobial activity is important and is clinically relevant. The use of antimicrobial dental materials is important unless such characteristics are gained to the detriment of other material properties.
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http://dx.doi.org/10.1016/j.dental.2014.12.005DOI Listing
April 2015

In situ assessment of the setting of tricalcium silicate-based sealers using a dentin pressure model.

J Endod 2015 Jan 30;41(1):111-24. Epub 2014 Oct 30.

Faculty of Dental Surgery, Department of Restorative Dentistry, University of Malta, Msida, Malta. Electronic address:

Introduction: EndoSequence BC Sealer (Brasseler, Savannah, GA) is a premixed tricalcium silicate-based root canal sealer that requires moisture from the root dentin to hydrate. The aim of this study was to investigate the setting of EndoSequence BC Sealer and other sealers in contact with human dentin in a simulated clinical environment.

Methods: EndoSequence BC Sealer, MTA Fillapex (Angelus, Londrina, Brazil), Septodont Sealer (Septodont, Saint Maur-des-Fosses, France), and Apexit Plus (Ivoclar, Schaan, Lichtenstein) were assessed. Caries-free lower premolars extracted for orthodontic purposes in patients aged 13-16 years were standardized to a 10-mm root length and were filled with test sealers and set up in a dentin pressure model for 14 days. In addition, set sealers immersed in physiologic solution for 14 days were also assessed. The set materials in solution and materials retrieved from the dentin pressure setup were characterized by scanning electron microscopy and X-ray diffraction analysis. The setting time and radiopacity were assessed using ISO 6876:2002 specifications. Furthermore, mineral ion leaching was evaluated by inductively coupled plasma mass spectrometry.

Results: All the sealers tested exhibited formation of a calcium phosphate phase when in contact with physiologic solution. Septodont Sealer and Apexit Plus did not exhibit the formation of a calcium phosphate phase in the dentin pressure setup. The fluid in the system was enough to allow the setting of EndoSequence BC Sealer, which did not set in a dry environment. All materials leached calcium with the Septodont Sealer, exhibiting double the calcium ion leaching compared with EndoSequence BC Sealer.

Conclusions: Using the dentinal fluid pressure system resulted in an adequate flow of dentinal fluid that allowed EndoSequence BC Sealer to set inside the root canal. Although the sealers tested were tricalcium silicate based, the hydration reaction and bioactivity in the presence of dentinal fluid were different to hydration in vitro. Thus, clinically, material bioactivity cannot be assumed.
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http://dx.doi.org/10.1016/j.joen.2014.09.015DOI Listing
January 2015

Tricalcium silicate cements with resins and alternative radiopacifiers.

J Endod 2014 Dec 1;40(12):2030-5. Epub 2014 Oct 1.

Department of Restorative Dentistry, Faculty of Dental Surgery, University of Malta, Malta. Electronic address:

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.
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http://dx.doi.org/10.1016/j.joen.2014.08.016DOI Listing
December 2014

Hydration of Biodentine, Theracal LC, and a prototype tricalcium silicate-based dentin replacement material after pulp capping in entire tooth cultures.

J Endod 2014 Nov 22;40(11):1846-54. Epub 2014 Aug 22.

Aix-Marseille Université, CNRS, ISM UMR 7287, Marseille, France. Electronic address:

Introduction: The calcium-releasing ability of pulp-capping materials induces pulp tissue regeneration. Tricalcium silicate-based materials produce calcium hydroxide as a by-product of hydration. Assessment of hydration and calcium ion leaching is usually performed on samples that have been aged in physiological solution for a predetermined period of time. The hydration and activity of the materials in vivo may not be similar to those displayed in vitro because of insufficient fluid available in contact with dentin. The aim of this research was the assessment of hydration of Biodentine, Theracal LC, and a prototype radiopacified tricalcium silicate-based material after pulp capping and to compare it with direct hydration in an aqueous solution.

Methods: The extent of hydration of Biodentine, Theracal LC, and a prototype radiopacified tricalcium silicate-based material with a similar composition to Biodentine but not incorporating the additives was assessed by scanning electron microscopy and energy dispersive spectroscopy of polished specimens after being allowed to hydrate in Hank's balanced salt solution for 14 days. The extent of hydration was compared with material hydration when used as direct pulp capping materials by using a tooth culture model. Material activity was also assessed by x-ray diffraction analysis to investigate the deposition of calcium hydroxide by the materials, and calcium ion leaching in Hank's balanced salt solution was assessed by ion chromatography.

Results: Biodentine and the prototype tricalcium silicate cement hydrated and reaction by-products were deposited in the cement matrix both after pulp capping and when incubated in an aqueous solution. Calcium hydroxide was formed, and calcium ions were leached in solution. Theracal LC hydration was incomplete because of the limited moisture diffusion within the material. Thus, no calcium hydroxide was produced, and a lower calcium ion leaching was recorded.

Conclusions: Theracal LC had a heterogeneous structure with large unhydrated particles because not enough moisture was present to allow hydration to proceed. Biodentine composition was shown to be optimized, and the environmental conditions did not affect material microstructure. Biodentine exhibited formation of calcium hydroxide and calcium ion leaching, which are beneficial to the dental pulp.
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http://dx.doi.org/10.1016/j.joen.2014.06.018DOI Listing
November 2014

Sealers and warm gutta-percha obturation techniques.

J Endod 2015 Jan 10;41(1):72-8. Epub 2014 Aug 10.

Department of Restorative Dentistry, Faculty of Dental Surgery, University of Malta, Malta. Electronic address:

Introduction: Warm vertically compacted gutta-percha obturation techniques use root canal sealers that are heated during the obturation. This study aims at investigating the suitability of selected sealers with warm gutta-percha obturation techniques.

Methods: The composition of an experimental sealer (Septodont; Saint Maur-des-Fosses, France), MTA Fillapex (Angelus, Londrina, Brazil), Apexit Plus (Ivoclar, Schaan, Lichtenstein), and AH Plus (Dentsply International, Addlestone, UK) was assessed by scanning electron microscopic and energy-dispersive spectroscopic analysis. The effect of temperature during warm vertical compaction technique was investigated by testing the sealers' properties after 1 minute to 100°C or 37°C. The reaction products after setting were assessed by X-ray diffraction analysis and Fourier transform infrared spectroscopy. Changes in setting time, flow, and film thickness were determined using ISO 6876 (2012) specifications.

Results: The experimental tricalcium silicate-based sealer and Apexit Plus contained calcium hydroxide peaks after setting, which were absent in MTA Fillapex. The properties of AH Plus and the experimental sealer were modified by heat; the setting time was reduced, and film thickness increased. AH Plus had diminished N-H groups when heated to 100°C for 1 minute. MTA Fillapex, Septodont sealer, and Apexit Plus were unaffected by heat application.

Conclusions: The choice of sealer should be considered when selecting the obturation technique. The Septodont sealer is recommended for obturations using cold laterally condensed gutta-percha, whereas MTA Fillapex and Apexit Plus were suitable with warm gutta-percha obturation techniques.
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http://dx.doi.org/10.1016/j.joen.2014.06.007DOI Listing
January 2015

Assessment of color stability of white mineral trioxide aggregate angelus and bismuth oxide in contact with tooth structure.

J Endod 2014 Aug 18;40(8):1235-40. Epub 2014 Mar 18.

Department of Restorative Dentistry, Dental Materials and Endodontics, Bauru Dental School, University of São Paulo, Bauru, São Paulo, Brazil.

Introduction: Dental discoloration with use of materials containing bismuth oxide has been reported. It is postulated that the discoloration is a result of chemical interaction of bismuth oxide with dentin. The aim of the study was to analyze dental color alteration and the chemical interaction of bismuth oxide with the main components present in composite (methacrylate) and in dentin (collagen).

Methods: Fifty bovine teeth were prepared and filled with white mineral trioxide aggregate (MTA) Angelus, Portland cement (PC) with 20% zirconium oxide, or PC with 20% calcium tungstate and then sealed with composite. Triple antibiotic paste and unfilled samples were the positive and negative controls, respectively. The specimens were stored in separate flasks immersed in tap water at 37°C with ambient light blocked out. The color assessment was performed with a spectrophotometer at different intervals, namely before filling and 24 hours, 15 days, and 30 days after filling. The color change and the luminosity were calculated. The statistical analysis was performed by using nonparametric Kruskal-Wallis and Dunn tests (P < .05). The interaction of the bismuth oxide, zirconium oxide, and calcium tungstate with collagen and methacrylate was assessed by placing the materials in contact, followed by color assessment.

Results: The analysis of color change values showed that all the materials presented color alteration after the evaluated periods. Statistically higher luminosity was verified for PC/20% zirconium oxide in comparison with white MTA Angelus (P < .05). The teeth filled with white MTA Angelus demonstrated a grayish discoloration with evident dentin staining. Bismuth oxide exhibited a color change when in contact with collagen.

Conclusions: The color of white MTA Angelus was altered in contact with dental structures. Collagen, which is present in dentin matrix, reacted with bismuth oxide, resulting in a grayish discoloration. The use of an alternative radiopacifier to replace bismuth in white MTA is indicated.
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http://dx.doi.org/10.1016/j.joen.2014.01.044DOI Listing
August 2014

Chemical characterization and bioactivity of epoxy resin and Portland cement-based sealers with niobium and zirconium oxide radiopacifiers.

Dent Mater 2014 Sep 18;30(9):1005-20. Epub 2014 Jun 18.

Department of Restorative Dentistry, Faculty of Dental Surgery, University of Malta, Medical School, Mater Dei Hospital, Msida MSD 2090, Malta. Electronic address:

Objective: The purpose of this study was to characterize and to evaluate the bioactivity potential of experimental root canal sealers (ES) based on Portland cement, epoxy resin with nano- and micro-particles of niobium or zirconium oxide used as radiopacifiers in comparison to AH Plus and MTA Fillapex.

Methods: Specimens of the sealers (10 mm in diameter×1 mm thick) were prepared and the radiopacity was evaluated according to ISO 6876 (2012) specifications. Characterization of the sealers was performed under the scanning electron microscope (SEM) immediately after setting and after immersion for 28 days in Hank's balanced salt solution (HBSS). In addition X-ray energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy were also performed. The pH and calcium ion release were measured after 1, 7, 14, 21 and 28 days after completion of seating using a digital pH meter and an atomic absorption spectrophotometer, respectively.

Results: The experimental sealers exhibited an average radiopacity of 2.5 mm thickness of aluminum, which was similar to MTA Fillapex (P>0.05) and inferior to AH Plus (P<0.05). AH Plus did not show bioactivity. Although the experimental sealers did not exhibit the formation of hydration product, they encouraged the deposition of crystalline spherical structures of calcium deficient phosphate. The highest pH and calcium release values were observed with the experimental sealers (P<0.01). ES-Nb-micro was the only sealer to present hexagonal shaped crystal deposition.

Significance: Novel root canal sealers based on a mixture of Portland cement, epoxy resin and radiopacifier exhibited a degree of bioactivity although no evidence of cement hydration was demonstrated on material characterization. The radiopacifier particle size had limited effect on the sealer microstructure and chemical properties.
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http://dx.doi.org/10.1016/j.dental.2014.05.007DOI Listing
September 2014

Mercury intrusion porosimetry and assessment of cement-dentin interface of anti-washout-type mineral trioxide aggregate.

J Endod 2014 Jul 3;40(7):958-63. Epub 2014 Jan 3.

Department Restorative Dentistry, Faculty of Dental Surgery, University of Malta, Malta. Electronic address:

Introduction: One of the disadvantages of mineral trioxide aggregate (MTA) is washout (ie, the tendency of freshly prepared cement paste to disintegrate upon early contact with physiological fluids). A novel MTA (MTA Plus; Prevest Denpro, Jammu City, India) exhibits low washout and superior physical properties when mixed with a gel instead of water. When used as a root-end filler, MTA is in contact with both bone and root dentin. This study aimed to investigate the porosity and interfacial characteristics of the novel MTA mixed with water or antiwashout gel.

Methods: Porosity was evaluated after 1 or 28 days of immersion in Hank's balanced salt solution using mercury intrusion porosimetry. The root dentin to material interface was investigated using a scanning electron microscope and energy-dispersive X-ray spectroscopy complete with line scans and elemental maps.

Results: Anti-washout-type MTA Plus was found to have lower initial porosity than MTA Plus mixed with water although this trend was reversed after 28 days of immersion in physiological fluid. Both materials exhibited good marginal adaptation. The diffusion of silicon, calcium, and phosphorus across the cement/dentin interface was observed.

Conclusions: MTA Plus mixed with antiwashout gel was found to have lower initial porosity than MTA Plus mixed with water. Both materials exhibited good marginal adaptation and the diffusion of silicon, calcium, and phosphorous across the cement/dentin interface. Thus, the anti-washout-type MTA can be considered to be a suitable substitute for ordinary MTA in all its indications.
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http://dx.doi.org/10.1016/j.joen.2013.11.015DOI Listing
July 2014

Hydration characteristics of Biodentine and Theracal used as pulp capping materials.

Dent Mater 2014 Jul 29;30(7):709-15. Epub 2014 Apr 29.

Department of Restorative Dentistry, Faculty of Dental Surgery, University of Malta, Medical School, Mater Dei Hospital, Msida MSD 2090, Malta. Electronic address:

Objectives: Investigation of the hydration and characterization of Theracal and Biodentine used for pulp capping.

Methods: The setting mechanism and characterization of set Biodentine and Theracal after immersion in Hank's balanced salt solution (HBSS) for 28 days was investigated by scanning electron microscopy (SEM) of polished specimens and X-ray diffraction (XRD) analysis. The bioactivity and surface microstructure of cements immersed in HBSS or water was also assessed by similar techniques together with leaching in solution investigated by ion chromatography (IC).

Results: Biodentine hydration resulted in the formation of calcium hydroxide which was present in the material matrix and also on the material surface. Theracal was composed of large cement particles which showed some evidence of reaction rims on hydration. The material matrix included a barium zirconate phase as radiopacifier and also a glass phase composed of strontium, silicon and aluminum. This phase could not be detected in XRD analysis. Formation of a calcium phosphate phase was demonstrated on Theracal immersed in HBSS. Both materials leached calcium ions in solution.

Conclusions: The presence of a resin matrix modifies the setting mechanism and calcium ion leaching of Theracal. The clinical implications of these findings need to be investigated.
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http://dx.doi.org/10.1016/j.dental.2014.03.012DOI Listing
July 2014

Investigation of the effect of sealer use on the heat generated at the external root surface during root canal obturation using warm vertical compaction technique with System B heat source.

J Endod 2014 Apr 30;40(4):555-61. Epub 2013 Oct 30.

Department of Restorative Dentistry, Faculty of Dental Surgery, University of Malta, Malta. Electronic address:

Introduction: During warm vertical compaction of gutta-percha, root canal sealers with different chemical compositions absorb the heat generated inside the root canal. The aim of this research was to assess physicochemical modifications of sealers subjected to the System B heat source (Analytic Technology, Redmond, WA) and to evaluate the effect that the use of different sealers has on the heat transfer to the external root surface.

Methods: Three proprietary brand sealers (AH Plus [Dentsply International, Addlestone, UK], Pulp Canal Sealer [Kerr Corporation, Orange, CA], MTA Fillapex [Angelus Dental Solutions, Londrina, PR, Brazil]) and a prototype sealer based on Portland cement were assessed. The heat generated on the surfaces of System pluggers and the heat dissipation at different levels (apical, midroot, and cervical) over root surface while using different sealers was assessed using thermocouples. Data were collected in 3 different environmental conditions with the tooth suspended in air, immersed in Hank's balanced salt solution, or gelatinized Hank's balanced salt solution. Chemical changes in the sealers induced by the heat were monitored by Fourier transform infrared spectroscopy. The effect of heat changes on the setting time and compressive strength of the sealers was also assessed.

Results: The continuous wave plugger sustained a rise in temperature at a maximum of 80°C at the instrument shank. The highest change in temperature on the external root surface was recorded after 1.5 minutes from the start of heating, and it was restored to body temperature by 6 minutes. Environmental conditions affected heat dissipation for all the sealers in the midroot and cervical regions and the highest increase in temperature (∼60°C) recorded in air. In the midroot and cervical regions, the type of sealer used did not affect the rise in temperature. In the apical region, AH Plus obturations resulted in a greater rise in temperature, and the chemical composition of this sealer was affected by high temperature; it also induced a reduction in sealer setting time and strength.

Conclusions: It could be concluded that surrounding conditions, such as temperature and humidity, exerted influence on heating dissipation during the continuous wave of the condensation obturation technique and that root canal sealers presented different conductive/isolating properties. Furthermore, the physical and chemical properties of AH Plus were negatively affected by the changes in temperature.
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http://dx.doi.org/10.1016/j.joen.2013.09.026DOI Listing
April 2014
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