Dr. MH. Nekoofar

DDS, MSc, DoIBoE, PhD

Author: admin

  • Microstructure and Chemical Analysis of Four Calcium Silicate-Based Cements in Different Environmental Conditions

    Abstract

    Objective The objective of this study was to analyze the microstructure and crystalline structures of ProRoot MTA, Biodentine, CEM Cement, and Retro MTA when exposed to phosphate-buffered saline, butyric acid, and blood.

    Methods and materials Mixed samples of ProRoot MTA, Biodentine, CEM Cement, and Retro MTA were exposed to either phosphate-buffered saline, butyric acid, or blood. Scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopic (EDX) evaluations were conducted of specimens. X-ray diffraction (XRD) analysis was also performed for both hydrated and powder forms of evaluated calcium silicate cements.

    Results The peak of tricalcium silicate and dicalcium silicate detected in all hydrated cements was smaller than that seen in their unhydrated powders. The peak of calcium hydroxide (Ca(OH)2) in blood- and acid-exposed ProRoot MTA, CEM Cement, and Retro MTA specimens were smaller than that of specimens exposed to PBS. The peak of Ca(OH)2 seen in Biodentine™ specimens exposed to blood was similar to that of PBS-exposed specimens. On the other hand, those exposed to acid exhibited smaller peaks of Ca(OH)2.

    Conclusion Exposure to blood or acidic pH decreased Ca(OH)2 crystalline formation in ProRoot MTA, CEM Cement and Retro MTA. However, a decrease in Ca(OH)2 was only seen when Biodentine™ exposed to acid.

    Clinical relevance The formation of Ca(OH)2 which influences the biological properties of calcium silicate cements was impaired by blood and acid exposures in ProRoot MTA, CEM Cement, and Retro MTA; however, in the case of Biodentine, only exposure to acid had this detrimental effect.

    Keywords: Biodentine, Calcium Silicate Cement, CEM Cement, EDX, MTA, SEM, XRD.

  • Does the mixing and placement regime affect the pH of Mineral Trioxide Aggregate?

    Abstract

    Aim: The objective of this study was to measure in a laboratory setting the pH of tooth coloured ProRoot MTA and MTA Angelus following various mixing and placement techniques, including mechanical mixing, manual mixing and indirect ultrasonic activation.

    Materials and Method: Tooth coloured ProRoot MTA and White MTA Angelus were used. One gram of each powder was mixed with a 0.34 g of distilled water that were allocated to eight experimental groups, each containing three specimens. Four groups were prepared by mechanical mixing of capsules for 30 s at 4500 rpm the other four were mixed manually. Half of the specimens in each group were placed in moulds using indirect ultrasonic activation. pH values were recorded directly from within the freshly mixed material and were analyzed using one-way ANOVA at a 0.05 level of significance.

    Results: No significant difference in pH was found between the mixing and placement techniques or the materials tested. The highest pH value recorded was in the ProRoot group that was mixed manually and placed ultrasonically (11.64). The Angelus group, which was mixed manually without an ultra-sonic agitation, had the lowest pH values (10.42).

    Conclusion: Mechanical mixing and ultrasonication confer-red no significant disadvantage in terms of the initial pH of the material. Since mechanical agitation of encapsulated cements provides more consistent mixes, it might be possible to use this technique combined with ultrasonic agitation as an alternative to manual mixing, both in clinical and in laboratory conditions, in order to achieve standardization of the material so as to enhance its properties.

    Keywords: PH, Placement, MTA, Mixing.

     Does the mixing and placement regime affect the pH of Mineral Trioxide Aggregate.pdf

  • The Role of Stem Cell Therapy in Regeneration of Dentine-Pulp Complex: A Systematic Review

    Abstract

    Infection of the dental pulp will result in inflammation and eventually tissue necrosis which is treated conventionally by pulpectomy and root canal treatment. Advances in regenerative medicine and tissue engineering along with the introduction of new sources of stem cells have led to the possibility of pulp tissue regeneration. This systematic review analyzes animal studies published since 2010 to determine the ability of stem cell therapy to regenerate the dentine-pulp complex (DPC) and the success of clinical protocols. In vitro and human clinical studies are excluded and only the experimental studies on animal models were included. Dental pulp stem cells constitute the most commonly used cell type. The majority of stem cells are incorporated into various types of scaffold and implanted into root canals. Some of the studies combine growth factors with stem cells in an attempt to improve the outcome. Studies of ectopic transplantation using small animal models are simple and non-systematic evaluation techniques. Stem cell concentrations have not been so far reported; therefore, the translational value of such animal studies remains questionable. Though all types of stem cells appear capable of regenerating a dentine-pulp complex, still several factors have been considered in selecting the cell type. Co-administrative factors are essential for inducing the systemic migration of stem cells, and their vascularization and differentiation into odontoblast-like cells. Scaffolds provide a biodegradable structure able to control the release of growth factors. To identify problems and reduce costs, novel strategies should be initially tested in subcutaneous or renal capsule implantation followed by root canal models to confirm results.

    Keywords: Dentin-Pulp Complex, Dentinogenesis, Regenerative Medicine, Stem Cell Therapy, Tissue Engineering.

     The Role of Stem Cell Therapy in Regeneration of Dentine-Pulp Complex A Systematic Review.pdf

  • Effect of Blood Contamination on the Compressive Strength of Three Calcium Silicate‐Based Cements

  • Dental Pulp Response to RetroMTA after Partial Pulpotomy in Permanent Human Teeth

    Abstract

    Introduction: A lack of information exists regarding the efficacy of RetroMTA (BioMTA, Seoul, Korea) directly applied on the pulp in vital pulp therapy. This study was designed to examine the clinical efficacy of RetroMTA compared with ProRoot mineral trioxide aggregate (MTA) (Dentsply Tulsa Dental, Tulsa, OK) for partial pulpotomy.

    Methods: Partial pulpotomy was performed in 22 healthy human maxillary and mandibular third molars planned for extraction. The teeth were randomly divided into 2 groups (n = 11) and underwent partial pulpotomy with RetroMTA and ProRoot MTA as the control. The teeth were then restored with glass ionomer cement. Clinical and electric pulp tests were performed after 1 and 8 weeks. The teeth were radiographed and extracted at 8 weeks. Histologic sections were prepared and analyzed for pulp inflammation and dentinal bridge formation. Data were analyzed using the Mann-Whitney U test.

    Results: Clinical examination after 1 and 8 weeks showed no sensitivity to heat, cold, or palpation in the ProRoot MTA and RetroMTA groups. Periapical radiographs taken before the extraction of teeth showed no evidence of periapical pathology. Electric pulp testing revealed no sensitivity. Data comparisons using the Mann-Whitney U test showed no significant difference between the materials with regard to the pulp inflammation type, intensity and extension (P = .3), or bridge continuity (P = .12). However, these data revealed a significant difference between the 2 materials in pulp morphology (P < .05) and bridge thickness (P < .01).

    Conclusions: This is the first work to evaluate a RetroMTA histologic outcome in partial pulpotomy in human permanent teeth. It shows pulp disorganization, an absence of inflammation, and discontinuous mineralization, which may represent a potential drawback with RetroMTA in this indication.

    Keywords: Partial pulpotomy; ProRoot MTA; RetroMTA; permanent human teeth; vital pulp therapy.

     Dental Pulp Response to RetroMTA after Partial Pulpotomy in Permanent Human Teeth.pdf

  • Bonding to Caries Affected Dentine

    Abstract

    Objectives: Dentine replacement materials are often placed over caries affected dentine (CAD). The aim of this study was to compare the bonding characteristics and interactions of selected hydraulic calcium silicate-based dentine replacement materials to CAD and sound dentine.

    Methods: Three hydraulic calcium silicate-based dentine replacement materials were assessed: Retro MTA, Biodentine and Theracal LC. Material characterization was done by scanning electron microscopy and X-ray diffraction analyses. Blocks of sound and CAD were prepared and standardized by Vickers microhardness testing. Half of the affected and sound dentine blocks were pretreated with 5.25% NaOCl prior to material placement. The materials were stored either for 1 week or 24 weeks in 37°C in fully saturated conditions. Shear bond strength was assessed at both time periods. Radiopacity of the interfacial dentine was also evaluated to assess the remineralization potential of the dentine replacement materials.

    Results: The reaction of Theracal was slower than that of the water-based materials. The bond strengths of different materials did not differ after 1 week (P>0.05). The bond strength of Biodentine and Retro MTA increased over time but no change was observed for Theracal. NaOCl pre-treatment deteriorated the bond strength to sound dentine but improvement was observed in affected dentine. Radiopacity changes were observed after 24 weeks.

    Significance: Biodentine and Retro MTA showed better bonding to CAD. Pretreatment with NaOCl improved the bond strength of dentine replacement materials to CAD.

    Keywords: Caries, Characterization, Dentine Replacement Materials, Shear Bond Strength, Demineralized Dentine, Remineralization.

     Bonding to Caries Affected Dentine.pdf

  • X-Ray Diffraction Analysis of MTA Mixed and Placed with Various Techniques

    Abstract

    Objectives The aim of this study was to evaluate the effect of various mixing techniques as well as the effect of ultrasonic placement on hydration of mineral trioxide aggregate (MTA) using X-ray diffraction (XRD) analysis.

    Materials and Methods One gram of ProRoot MTA and MTA Angelus powder was mixed with a 0.34-g of distilled water. Specimens were mixed either by mechanical mixing of capsules for 30 s at 4500 rpm or by manual mixing followed by application of a compaction pressure of 3.22 MPa for 1 min. The mixtures were transferred into the XRD sample holder with minimum pressure. Indirect ultrasonic activation was applied to half of the specimens. All specimens were incubated at 37 °C and 100% humidity for 4 days. Samples were analyzed by XRD. Phase identification was accomplished by use of search-match software utilizing International Centre for Diffraction Data (ICDD).

    Results All specimens comprised tricalcium silicate, calcium carbonate, and bismuth oxide. A calcium hydroxide phase was formed in all ProRoot specimens whereas among MTA Angelus groups, it was found only in the sample mixed mechanically and placed by ultrasonication.

    Conclusions Mechanical mixing followed by ultrasonication did not confer a significant disadvantage in terms of hydration characteristics of MTA.

    Clinical Relevance Clinicians vary in the way they mix and place MTA. These variations might affect their physical characteristics and clinical performance. For ProRoot MTA, the mixing and placement methods did not affect its rheological properties, whereas for MTA Angelus, mechanical mixing combined with ultrasonic placement enhanced the calcium hydroxide phase formation.

    Keywords: Calcium Hydroxide, MTA, Mechanical Mixing, Ultrasonic Agitation, X-ray diffraction Analysis, XRD.

     X-Ray Diffraction Analysis of MTA Mixed and Placed with Various Techniques.pdf

  • The Micro-Shear Bond Strength of Various Resinous Restorative Materials to Aged Biodentine

    Abstract

    Introduction: The type of materials and application time of veneering restorations on calcium silicate cements are important factors which influence the interfacial properties. The aim of this study was to measure the micro-shear bond strength of a resin composite (RC) using several adhesive systems and a resin-modified glass ionomer cement (RM-GIC) to different aged Biodentine specimens.

    Methods and Materials: A total of 15 Biodentine blocks were prepared and assigned to three aging periods: 12 min, one week and one month. Then they were subdivided into five sub-groups to receive cylinders of resinous materials. RC was applied using different adhesive systems: A) no adhesive B) etch and rinse C) two-step self-etch and D) universal adhesive in self-etch mode and E) RM-GIC applied directly over Biodentine. Micro-shear bond strength was measured and the data were analyzed using one-way and two-way ANOVA. The level of significance was set at 0.05.

    Result: There was significant interaction between Biodentine aging periods and resinous materials (P<0.05). The highest value was obtained in group D bonded to the recently set Biodentine. Increasing the aging period to one week resulted in increased micro-shear bond strength in all groups expect for group D. One-month incubation time led to reduced shear bond strength in group A, C and D. Micro-shear bond strength values of group E increased to the longer aged Biodentine.

    Conclusion: Group D showed the highest bond strength to freshly mixed Biodentine.

    Keywords: Bond Strength, Composite Resin, Dental Adhesive, Glass Ionomer Cement, Tricalcium Silicate.

     The Micro-Shear Bond Strength of Various Resinous Restorative Materials to Aged Biodentine.pdf

  • Human Pulp Responses to Partial Pulpotomy Treatment with TheraCal as Compared with Biodentine and ProRoot MTA: A Clinical Trial

    Abstract

    Introduction: Questions exist regarding the efficacy of resin-containing materials such as TheraCal directly applied on the pulp. This study sought to investigate the clinical efficacy of TheraCal as compared with Biodentine and ProRoot mineral trioxide aggregate (MTA) for partial pulpotomy.

    Methods: In this clinical trial, partial pulpotomy was performed for 27 sound human maxillary and mandibular third molars scheduled for extraction. The teeth were randomly divided into 3 groups (n = 9) and underwent partial pulpotomy with TheraCal, Biodentine, and ProRoot MTA. The teeth were then restored with glass ionomer cement. Clinical and electric pulp tests were performed after 1 and 8 weeks. The teeth were radiographed and extracted at 8 weeks. Histologic sections were prepared and analyzed for pulp inflammation and dentinal bridge formation. Data were analyzed by using one-way analysis of variance.

    Results: Clinical examination showed no sensitivity to heat, cold, or palpation in ProRoot MTA and Biodentine groups. Two patients in TheraCal group (20%) reported significant pain at 1 week. Periapical radiographs showed no periapical pathology, and electric pulp test revealed a normal pulp response with no hypersensitivity. Inflammation was absent with all materials at 8 weeks. Normal pulp organization was seen in 33.33% of the teeth in ProRoot MTA, 11.11% in TheraCal, and 66.67% in Biodentine group (P = .06). Biodentine group showed complete dentinal bridge formation in all teeth, whereas this rate was 11% and 56% in TheraCal and ProRoot MTA groups, respectively (P = .001).

    Conclusions: Overall, Biodentine and MTA performed better than TheraCal when used as partial pulpotomy agent and presented the best clinical outcomes.

    Keywords: Biodentine, partial pulpotomy, ProRoot MTA, TheraCal.

     Human Pulp Responses to Partial Pulpotomy Treatment with TheraCal as Compared with Biodentine and ProR.pdf

  • Histologic Tissue Response to Furcation Perforation Repair Using Mineral Trioxide Aggregate or Dental Pulp Stem Cells Loaded onto Treated Dentin Matrix or Tricalcium Phosphate

    Abstract

    Objectives: The aim of this study is to compare the effect of treated dentine matrix (TDM) and tricalcium phosphate (TCP) scaffolds on odontogenic differentiation and mineralization of dental pulp stem cells (DPSCs) in furcation perforations created in the pulp chamber floor of premolar teeth in dogs.

    Material and Methods: DPSCs were isolated and cultured from the dental pulp of the maxillary left second and third premolars of dogs. The DPSCs were loaded on TCP (SC+TCP) and TDM (SC+TDM) scaffolds and inserted into intentionally perforated pulp chamber floors of premolars in dogs; six teeth were used for each group. Three more groups of six specimens were created, and mineral trioxide aggregate (MTA), TDM, and TCP were inserted into the perforations to act as controls. An intact premolar and no treatment in the perforation site were used as positive and negative controls respectively. After 3 months, the animals were sacrificed and the type of inflammation, presence of dentine, continuation and type of cementum, type of connective tissue, and presence of foreign body reaction were evaluated, and significant differences were between groups determined using the Fisher’s exact test. The evaluation of the amount of inflammation and the percentage of new bone formation was evaluated using the Mann-Whitney U test.

    Results: The negative control group was associated with severe inflammation and granulation tissue formation. In the positive control group, intact periodontal tissues and no inflammation were observed. Dentine bridge formation was not seen in specimens of any group. The specimens in the SC+TDM group were associated with significantly more bone formation than other groups (P < 0.001). The amount of inflammation was less than 10 % in specimens of all groups with the exception of three specimens in the TCP group that were categorized as 10–30 %. Chronic inflammation without foreign body reactions was the major pattern of inflammation in groups. Formation of cementum with a cellular and continuous appearance was seen in all specimens.

    Conclusions: SC+TDM was associated with significantly more bone formation when used to repair uninfected furcation perforations in the premolar teeth of dogs. Clinical relevance Application of TDM as a biological scaffold in combination with DPSCs may offer an advantage during the repair of root perforation defects.

    Keywords: Bioactive Scaffold Materials, Regeneration, Stem Cells, Treated Dentin matrix (TDM), Tricalcium Phosphate (TCP).

     Histologic tissue response to furcation perforation repair using-2017.pdf