Digital assessment of properties of the three different generations of dental elastomeric impression materials.

BACKGROUND: This study aimed to compare the dimensional accuracy, hydrophilicity and detail reproduction of the hybrid vinylsiloxnether with polyether and polyvinylsiloxane parent elastomers using modified digital techniques and software. This was done in an attempt to aid in solving the conflict between the different studies published by competitive manufacturers using different common manual approaches. METHODS: A polyether, polyvinylsiloxanes and vinyl polyether silicone hybrid elastomeric impression materials were used in the study. Dimensional accuracy was evaluated through taking impressions of a metallic mold with four posts representing a partially edentulous maxillary arch, that were then poured with stone. Accuracy was calculated from the mean of measurements taken between fixed points on the casts using digital single-lens reflex camera to produce high-resolution digital pictures for all the casts with magnification up to 35×. Hydrophilicity was assessed by contact angle measurements using AutoCAD software. The detail reproduction was measured under dry conditions according to ANSI/ADA Standard No. 19 and under wet conditions as per ISO 4823. A metallic mold was used with three V shaped grooves of 20, 50, and 75 µm width. Specimens were prepared and examination was made immediately after setting using digital images at a magnification of 16×. RESULTS: The hybrid impression (0.035 mm) material showed significantly higher dimensional accuracy compared to the polyether (0.051 mm) but was not as accurate as the polyvinyl siloxane impression material (0.024 mm). The contact angles of the hybrid material before and after setting was significantly lower than the parent materials. With regard to the detail reproduction, the three tested materials were able precisely to reproduce the three grooves of the mold under dry conditions. Whereas, under wet conditions, the hybrid material showed higher prevalence of well-defined reproduction of details same as polyether but higher than polyvinylsiloxane that showed prevalence of details with loss of sharpness and continuity. CONCLUSIONS: The digital technique used could be a more reliable and an easier method for assessment of impression materials properties. The hybridization of polyvinyl siloxane and polyether yielded a promising material that combines the good merits of both materials and overcomes some of their drawbacks.

Tear strength and elastic recovery of new generation hybrid elastomeric impression material: A comparative study.

OBJECTIVE: Since there is no material in the market met all the ideal requirements of an impression material, thus in an attempt to find one, hybridization between the two most commonly used impression materials were done. The aim of the hybridization was to obtain a new material combining the good merits of both and eliminate their shortcomings. Thus, this study aimed to assess the impact of hybridization between polyether with addition silicone on tear strength and elastic recovery of the new material and compare such effect with regard to parent materials. RESULTS: A polyether (PE), polyvinyl siloxanse (PVS) and vinyl polyether silicone (VPES) hybrid elastomers were used in the present study. Tear strength was measured one hour after setting time of each material according to the manufacturer and the three materials showed statistically comparable tear strength in N/mm. Elastic recovery was evaluated one minute after the setting time recommended by the manufacturer. The three materials were statistically insignificant from each other, and all met the ISO4823 requirement of having greater than 96.5% recovery.

In Vitro Biological Evaluation of a Fabricated Polycaprolactone/Pomegranate Electrospun Scaffold for Bone Regeneration.

Different scaffold biomaterials are being investigated as a solution for bone loss due to disease or trauma. The aim of this study is the fabrication, characterization, and in vitro biological evaluation of a novel polycaprolactone (PCL) nanoscaffold incorporating pomegranate peel extract (PG) for bone regeneration. Using electrospinning, three groups of scaffolds were prepared: the control group PCL and two groups of PCL with PG concentrations (11 and 18 weight %). The antioxidant activity and the total phenolic content (TPC) of the fabricated nanoscaffolds were evaluated, in addition to the porosity and degradation measurement. Cultured osteoblasts derived from rabbit bone marrow mesenchymal stem cells were used for the assessment of cell proliferation and attachment on the scaffold's surface. Scaffolds' characterization showed uniform nanofibers (NFs) with a fiber diameter range of 149-168 nm. Meanwhile, higher antioxidant activity and TPC of the PG groups were detected. Furthermore, total porosities of 59 and 62% were determined for the PCL-PG scaffolds. An increased degradation rate and significant improvement in cell proliferation and cell attachment were revealed for the PCL-PG fabricated scaffolds. Such incorporation of natural food waste, PG, in PCL NFs offered novel PCL-PG scaffolds as a promising candidate for bone regeneration applications.

Influence of Nanocoats on the Physicomechanical Properties and Microleakage of Bulk-fill and Resin-modified Glass Ionomer Cements: An In Vitro Study.

AIM: To analyze the impact of two nanocoating materials, EQUIA Forte nanocoat and universal adhesive, on flexural strength, color changes, surface roughness, and microleakage of bulk-fill and resin-modified glass ionomer cements (RM-GICs). MATERIALS AND METHODS: A total of 45 specimens were prepared for each group, bulk-fill (EQUIA Forte Fil) and RM-GI (Fuji II LC) cements, according to manufacturer's instructions for flexural strength, color change, and surface roughness tests. Each group was equally subdivided into three subgroups according to coating materials used; either without a coat (negative control) or covered with EQUIA Forte coat or universal adhesive. For the flexural strength test, 15 bar-shaped specimens were prepared using a rectangular-split Teflon mold (25 × 2 × 2 mm), then the test was conducted using a universal testing machine. Thirty disk-shaped specimens were prepared for color change and surface roughness tests using cylindrical-split Teflon mold (10 mm diameter and 2 mm height). The color change was measured using a spectrophotometer after immersion in tea infusion for seven days at room temperature. Surface roughness was examined using a profilometer after exposure to 2400 brushing cycles. Moreover, a microleakage test was conducted in 30 teeth restored with the same restorative protocols and evaluated using a stereomicroscope. Finally, the data were statistically analyzed. RESULTS: EQUIA Forte nanocoat subgroups exhibited the highest flexural strength in both tested GICs compared to other subgroups (91.07 ± 7.12 MPa for RM-GIC and 51.61 ± 4.42 MPa for bulk-fill GIC). For the color change, the lowest ΔE values for bulk-fill and RM-GICs were recorded in EQUIA Forte nanocoat subgroups (2.37 ± 0.25 and 2.97 ± 0.39, respectively) with no significant difference between both groups. The surface roughness of both GICs was significantly decreased in the coated subgroups either with EQUIA Forte coat or universal adhesive, with no significant difference between both coating agents. Also, microleakage was significantly decreased in the coated subgroups with no significant difference between the coating materials. CONCLUSION: Nanocoats, especially the EQUIA Forte nanocoat, positively impact the physicomechanical properties and adaptation of bulk-fill GICs and RM-GICs. CLINICAL SIGNIFICANCE: The application of nanocoats on GI restorations is highly recommended.

Chemical and biological evaluation of Egyptian Nile Tilapia (Oreochromis niloticas) fish scale collagen.

Collagen is considered to be one of the most useful biomaterials with different medical applications. However, collagen properties differ from one source to another. The aim of this study was to extract, purify, characterize and perform preliminary biological evaluation of type I collagen from scales of Egyptian Nile Tilapia. Pepsin-solubilized collagen (PSC) was successfully prepared from Nile Tilapia fish scale waste. Lyophilized collagen was dissolved in dilute HCl to form acidic collagen solutions (ACS) which was neutralized to form gel. To confirm the biocompatibility of the produced gel, baby hamster kidney (BHK-21) fibroblast cells were seeded onto a 3D collagen gel (0.3% and 0.5%, w/v). The results of an SDS-PAGE test showed that the extracted collagens were type I collagen, with α chain composition of (α1)2α2. Thermal analysis showed that the denaturation temperature was 32 °C. X-ray diffraction (XRD) analysis and Fourier-transform infrared spectra (FTIR) showed that the extracted collagen had a triple helix structure. Active proliferation of BHK-21 cells with no signs of toxicity was evident with both collagen gel concentrations tested. The results show that Nile Tilapia scales can be an effective source of collagen extraction that could be used as a potential biomaterial in biomedical applications.