Background
This study evaluated the ability of a CPP‐ACP‐modified Glass–ionomer cement (GIC) to inhibit demineralization around the margins of cervical cavities in natural teeth in comparison with a ...Giomer and conventional GIC with and without coating.
Methods
Thirty‐two sound human molars were used. Box‐shaped cavities were prepared along the CEJ. Teeth were randomly divided into four groups and restored with Equia Forte Fil, Coated Equia Forte Fil, Fuji VII EP or Beautifil II. Teeth were subjected to pH cycling. Micromorphological and elemental analyses were done using SEM and EDX. Polarized light microscope analysis and microhardness tests were also performed.
Results
Microhardness tests on enamel showed a significant difference between the coated Equia group, Equia and Beautifil II groups (P < 0.05). Dentine results showed significant differences between the coated Equia group and all other groups (P < 0.05). Elemental analysis showed significant differences in calcium weight percentage among the first and second observation levels in all groups (P < 0.05). A significant difference was found between the coated Equia group and the other three groups (P < 0.05).
Conclusions
All tested materials showed some ability to resist demineralization at the restoration margins. The coated GIC restoration showed better outcomes compared with the other tested materials.
Background
The aim of this study was to compare the flexural strength and Vickers hardness of tooth‐coloured restorative materials with and without applying a self‐adhesive coating for up to 6 ...months.
Methods
Specimens were prepared from three resin composites (RC), two resin‐modified glass‐ionomer cements (RM‐GIC) and two conventional glass‐ionomer cements (CGIC). All materials were tested both with and without applying G‐Coat Plus (GCP). Specimens were conditioned in 37 °C distilled deionized water for 24 h, and 1, 3 and 6 months. The specimens were strength tested using a four‐point bend test jig in a universal testing machine. The broken specimen's halves were used for Vickers hardness testing. Representative specimens were examined under an environmental scanning electron microscope.
Results
Data analysis showed that regardless of time and materials, generally the surface coating was associated with a significant increase in the flexural strength of the materials. Applying the GCP decreased the hardness of almost all materials significantly (P < 0.05) and effect of time intervals on hardness was material dependent.
Conclusions
The load‐bearing capacity of the restorative materials was affected by applying self‐adhesive coating and ageing. The CGIC had significantly higher hardness but lower flexural strength than the RM‐GIC and RC.
Abstract A new glass-ionomer cement (GIC) (Fuji VII™ EP) includes 3% (w/w) casein phosphopeptide–amorphous calcium phosphate (CPP–ACP) to enhance ion release. Objectives To assess this new GIC ...compared with a GIC without CPP–ACP (Fuji VII™) with respect to ion release, changes in surface hardness and in mass under a variety of acidic and neutral conditions. Methods Eighty blocks of Fuji VII™ (F7) and Fuji VII™ EP (F7EP) were subjected to three acidic solutions (lactic and citric acids pH 5.0, hydrochloric acid pH 2.0) and water (pH 6.9) over a three-day period. Ion release, surface hardness and weight measurements were carried out every 24 h. Results Higher calcium ion release from F7EP was observed under all acidic conditions. Increased inorganic phosphate ion release was observed for F7EP in hydrochloric and citric acids. Fluoride ion release was similar between F7 and F7EP under all conditions but was significantly higher in acids compared with water. After three days there was no significant difference in surface hardness ( p > 0.05) between the two materials under all conditions except hydrochloric acid. Minimal change in mass was observed for F7 and F7EP in water, lactic and hydrochloric acids, however citric acid caused significantly more mass loss compared with water ( p < 0.001). Conclusion Incorporation of 3% (w/w) CPP–ACP into F7 enhanced calcium and phosphate ion release, with no significant change in fluoride ion release and no adverse effects on surface hardness or change in mass. Clinical significance statement GICs have the potential to release fluoride ions particularly under acidic conditions associated with dental caries and erosion. A new GIC containing CPP–ACP and fluoride releases not only fluoride ions but also calcium and phosphate ions under acidic conditions which should help to inhibit demineralisation associated with caries and erosion.
Aim To evaluate the push‐out bond strength of the dentine–sealer interface with and without main cone for three resin sealers.
Methodology Thirty extracted maxillary premolar teeth with two ...separate canals were prepared using 0.04 taper Profile instruments to size 35–45. Teeth were divided into three groups for filling using AH Plus™, EndoREZ® or Resilon® sealers. In each tooth, one canal was filled with a matching single‐cone technique, and other was filled with sealer alone. A 1 mm slice of mid‐root dentine was prepared for the push‐out test. Failure modes after push‐out were examined under microscopy and field emission‐scanning electron microscopy. Data were analysed using two‐way anova and paired t‐tests, with significance set at P < 0.05.
Results Overall, the epoxy resin‐based sealer provided the highest push‐out bond strengths. Push‐out bond strengths were significantly higher (P < 0.001) when canals were filled with sealer alone than those filled with main cone and sealer (AH Plus™ 6.6 and 2.0 MPa, respectively; Resilon® 3.4 and 0.4 MPa; EndoREZ® 0.9 and 0.4 MPa). Sealers appeared to behave differently as thin films in association with a main cone, compared with bulk material. They failed in cohesive mode within the thin film, leaving a layer of sealer on the canal surface. Bulk sealer showed predominantly adhesive failure at the dentine–sealer interface, with a clean dentine wall and with resin tags either partially pulled out or sheared off at the interface.
Conclusion Push‐out bond strengths of resin sealers were much lower when the sealer was present as a thin layer.
The aim of this literature review is to explore the treatment methods for root caries in laboratory and clinical research in the last decade. A systematic search of publications in PubMed and Web of ...Science databases was performed. The timespan was limited to the last 10 years and English language. Further retrieval was conducted using the search terms of specific therapies or treatments. Eighty‐two articles were included in this systematic review and full texts were retrieved. Types of studies included laboratory studies and clinical trials. Therapeutic approaches for root caries without risk of pulp exposure can be categorized into non‐invasive and restorative treatment. Non‐invasive treatments which targeted different causative factors of root caries have been developed in the last decade. Accordingly, several artificial caries model systems have been proposed for the study of root caries in the laboratory. Carious tissue excavation techniques and restorative materials and procedures have been modified to improve the prognosis of invasive treatment. It is of importance to determine the most appropriate therapy for root caries and further clinical trials are needed to draw firm conclusions concerning the efficacy and consistency of the various treatment methods proposed.
Background
This study aimed to fabricate a denture base resin (DBR) containing phytoncide microcapsules (PTMCs) and determine the mechanical properties of the resin and antifungal activity.
Methods
...Fifty‐four heat‐cured rectangular DBR specimens (64 × 10 × 3.3 ± 0.2 mm) containing nine concentrations of PTMC between 0 and 5% (wt/wt) were fabricated and subjected to a three‐point bending test. A phytoncide release bioassay was developed using DBR containing 0% and 2.5% PTMCs (wt/wt) in a 24 well‐plate assay with incubation of Porphyromonas gingivalis at 37 °C for 74 h. The antifungal activity of PTMCs against Candida albicans, in a pH 5.5 acidic environment was determined in a plate assay.
Results
Flexural strength decreased with increasing PTMC concentration from 97.58 ± 4.79 MPa for the DBR alone to 53.66 ± 2.46 MPa for DBR containing 5.0% PTMC. No release of phytoncide from the PTMCs in the DBR was detected at pH 7.4. The PTMCs had a minimal inhibitory concentration of 2.6% (wt/vol) against C. albicans at pH 5.5.
Conclusions
PTMCs can be added to DBR 2.5% (wt/wt) without adversely affecting flexural strength. PTMCs released the antimicrobial agent at pH 5.5 at concentrations sufficient to inhibit the growth of the C. albicans.
Background
This study investigated the physical properties and ion release of casein phosphopeptide‐amorphous calcium phosphate (CPP‐ACP)‐modified calcium silicate‐based cements (CSCs) and compared ...the properties of a trial mineral trioxide aggregate (MTA) with two commercially available CSCs, Biodentine™ and Angelus® MTA.
Methods
The setting time, solubility, compressive strength and Vickers surface microhardness of the three CSCs incorporated with 0%, 0.5%, 1.0%, 2.0% and 3.0% (w/w) CPP‐ACP were investigated. Release of calcium (Ca2+), phosphate ions (Pi) and pH of the test cements were measured after 24, 72, 168 and 336 h of storage.
Results
The addition of up to 1.0% CPP‐ACP into Biodentine™ and 0.5% into the other cements did not adversely affect their physical properties except for the setting time. The addition of 0.5% CPP‐ACP increased Ca2+ released from Biodentine™ (after 168 and 336 h), Angelus® MTA (after 168 h) and the trial MTA (after 72 h). The addition of 1.0–3.0% CPP‐ACP increased Ca2+ and Pi released from all the cements. Biodentine™ released more Ca2+ particularly in the early stages and showed shorter setting time and higher mechanical properties than the other cements. The mechanical properties of Angelus® MTA and the trial MTA were similar. All the cements produced highly alkaline storage solutions.
Conclusions
Up to 1.0% CPP‐ACP in Biodentine™ improves Ca2+ and Pi release and 0.5% CPP‐ACP in Angelus® MTA and the trial MTA improves Ca2+ release without altering the mechanical properties and solubility. The addition of CPP‐ACP into CSCs prolonged the setting time.
Previous studies have indicated that vertical root fracture tends to occur in a buccolingual direction, where dentin thickness is greatest. Factors potentially influencing the location and direction ...of root fracture include root canal shape, external root morphology, and dentin thickness. In this finite-element study, simulated root sections were varied systematically with respect to canal size and shape, external root morphology, and dentin thickness to determine their relative contribution to vertical root fracture. Similar models were constructed based on cross-sections of human tooth roots that had been fractured clinically or experimentally. Finite-element models demonstrated that canal curvature seems more important than external root morphology, in terms of stress concentration, and that reduced dentin thickness increases the magnitude but not the direction of maximum tensile stress. Models based on actual root fractures showed a strong similarity between tensile-stress distribution and fracture patterns.
To assess fracture strength and fracture patterns of root-filled teeth with direct resin composite restorations under static and fatigue loading.
MOD cavities plus endodontic access were prepared in ...48 premolars. Teeth were root filled and divided into three restorative groups, as follows 1) resin composite; 2) glass ionomer cement (GIC) core and resin composite; and 3) open laminate technique with GIC and resin composite. Teeth were loaded in a servohydraulic material test system. Eight samples in each group were subjected to stepped fatigue loading: a preconditioning load of 100 N (5000 cycles) followed by 30,000 cycles each at 200 N and higher loads in 50-N increments until fracture. Noncycled teeth were subjected to a ramped load. Fracture load, number of cycles, and fracture patterns were recorded. Data were analyzed using two-way analysis of variance and Bonferroni tests.
Fatigue cycling reduced fracture strength significantly (p<0.001). Teeth restored with a GIC core and a laminate technique were significantly weaker than the composite group (379±56 N, 352±67 N vs 490±78 N, p=0.001). Initial debonding occurred before the tooth underwent fracture. All failures were predominantly adhesive, with subcrestal fracture of the buccal cusp.
Resin composite restorations had significantly higher fracture strength than did other restorations. Fatigue cycled teeth failed at lower load than did noncycled teeth.
Aim To determine whether resin‐based sealer cements are able to strengthen root dentine, as measured by work of fracture (Wf), micro‐punch shear strength (MPSS) and resistance to vertical root ...fracture (VRF).
Methodology One hundred and twenty extracted premolar teeth were randomly assigned amongst four treatments before testing: intact, root canals prepared but unfilled, or root filled using epoxy‐ or urethane dimethacrylate (UDMA)‐based sealer (plus core material). Samples were then prepared for measuring Wf, MPSS or VRF using standard test procedures. Data were analyzed using one‐way anova with significance set at P < 0.05.
Results For all three tests, root canals filled using epoxy resin‐based sealer were not statistically significantly different compared with UDMA resin (P = 1 for Wf, P = 0.7 for MPSS and P = 0.12 for VRF), or different from both sound and prepared dentine (P > 0.05). There was also no significant difference between sound dentine and prepared dentine for both Wf (P = 0.92) and resistance to VRF (P = 1).
Conclusions Neither epoxy nor UDMA resins used as sealer cements enhanced fracture resistance of root dentine when placed within root canals of extracted teeth.
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