Lack of Neutralization of 10-MDP Primers by Zirconia May Affect the Degree of Conversion of Dual-cure Resin Cement.

CLINICAL RELEVANCE: Use of zirconia primers with a low pH and a high acidic monomer concentration should be employed in combination with dual-cure resin cements that are less sensitive to an acidic environment. Primers with lower 10-MDP concentrations attain better outcomes.

Nanofiller Particles and Bonding Durability, Water Sorption, and Solubility of Universal Adhesives.

The aim of this study was to evaluate the influence of nanofiller particles in simplified universal adhesive on the long-term microtensile bond strength and silver nitrate up-take, as well as water sorption and solubility. Commercial adhesives Ambar Universal (FGM) in nanofilled-containing version (filled) and same lot without fillers (unfilled) were donated and applied by means of etch-and-rinse strategy. Microtensile bond strength was surveyed after 24-hours or 1-year water storage. Silver nitrate uptake was assayed using scanning electron microscopy (SEM). Water sorption and solubility experiments were performed based on ISO 4049:2009. Statistical analysis was performed using two-way ANOVA and Tukey test (p<0.05). The bond strength of both the adhesives were statistically similar at 24 hours (p>0.05), but the filled group attained significant bond strength reduction after aging when compared to initial bond strength (p<0.001). Conversely, unfilled adhesive presented stable adhesion after 1-year storage (p=0.262). Silver nitrate uptake was similar for both adhesives, with little silver impregnation at the hybrid and adhesive layers. Water sorption was higher with filled adhesive compared to the unfilled one (p=0.01). Conversely, solubility was higher in unfilled in comparison to filled one (p=0.008). The presence of nanofillers in universal adhesive achieves higher water sorption and dentin bond degradation, which did not occur in the unfilled adhesive.

Radiopacity and mechanical properties of dental adhesives with strontium hydroxyapatite nanofillers.

OBJECTIVES: Dental resins filled with hydroxyapatite (HAp) nanoparticles have significantly revolutionized restorative dentistry offering advantages such as remineralization potential and increase of polymerization. However, these materials have limited radiopacity hindering the diagnosis of secondary caries. The present study investigated the development of a new radiopaque dental adhesive by incorporating novel pure strontium hydroxyapatite nanoparticles [Sr10(PO4)6(OH)2, SrHAp] synthesized by a simple hydrothermal method. METHODS: Strontium phosphates were prepared using co-precipitation (SrHAp0h) and hydrothermal treatment for 2 and 5h (SrHAp2h and SrHAp5h). The crystallinity, crystallite size, textural and morphology features of the nanoparticles were characterized by XRD, FT-IR, micro-Raman and TEM. Strontium hydroxyapatite (SrHAp) or calcium hydroxyapatite (HAp) nanoparticles were then incorporated (10 wt%) into an adhesive resin of a commercial three-step etch-and-rinse adhesive to evaluate the radiopacity of disk-shaped specimens, degree of conversion (DC) assessed by FT-IR and mechanical properties by three-point bending test. The unfilled adhesive was used as negative control. RESULTS: While SrHAp0h and SrHAp2h resulted a phase mixing, the pure and highly crystalline phase of strontium hydroxyapatite free of calcium was obtained with 5h hydrothermal treatment (SrHAp5h). The TEM images revealed nanorods morphology for SrHAp5h. SrHAps incorporated into adhesive showed higher radiopacity, no alteration on DC despite slightly reducing the mechanical properties. SIGNIFICANCE: Although the mechanical properties are slightly impaired, incorporation of SrHAp nanoparticles offers potential method to improve radiopacity of restorative dental resins, easing the tracking of actual remineralization effects and enabling diagnosis of recurrent caries.

Influence of collagen cross-linkers addition in phosphoric acid on dentin biomodification and bonding of an etch-and-rinse adhesive.

OBJECTIVE: To investigate the effects of natural collagen cross-linkers incorporation in phosphoric acid etchant on dentin biomodification, microtensile bond strength (µTBS) and nanoleakage (NL) of a two-step etch-and-rinse adhesive. METHODS: Experimental aqueous solution of 37% ortho-phosphoric acid were prepared with the addition of 2% biomodification agents: Lignin (LIG) from industrial paper production residue, Cardanol (CARD) from cashew-nut shell liquid, and Proanthocyanidin (PAC) from grape-seed extract. Negative control (NC) was acid solution without cross-linker whilst commercial control (CC) was Condac 37 gel (FGM). Dentin specimens were assayed by FTIR after 15s etching to detect collagen cross-linking. Extracted third molars were used for µTBS (n=7) and fracture mode analysis of Optibond S (Kerr), tested after 24h or 1000 thermal cycles. NL was surveyed by SEM. Statistical analysis was performed with two-way ANOVA and Tukey's test (p<0.05). RESULTS: FTIR confirmed cross-linking for all agents. µTBS of CC was the highest (46.6±6.2MPa), but reduced significantly after aging (35.7±5.2MPa) (p<0.001). LIG (30.6±3.7MPa) and CARD (28.3±1.8MPa) attained similar µTBS which were stable after aging (p>0.05). Fracture mode was predominantly adhesive. At 24h, all groups showed presence of silver uptake in hybrid layer, except CARD. After aging, CARD- and LIG-treated specimens exhibited little amount of silver penetration. CC, PAC and NC showed gaps, great nanoleakage at hybrid layer and presence of water channels in adhesive layer. SIGNIFICANCE: Altogether, ortho-phosphoric acid incorporated with LIG and CARD promotes stable resin-dentin bond strength with minor nanoleakage after aging, thereby achieving therapeutic impact without additional clinical steps.

Glycerol-dimethacrylate as alternative hydrophilic monomer for HEMA replacement in simplified adhesives.

OBJECTIVES: Hydroxyethyl-methacrylate (HEMA) is still widely used in simplified adhesives. Indeed, several shortcomings occur with this monomer, such as water uptake and formation of linear polymers. This study aimed to compare the effects of HEMA replacement by glycerol-dimethacrylate (GDMA) on selected physicochemical properties and bonding performance of simplified model adhesives. MATERIALS AND METHODS: Experimental simplified etch-and-rinse and self-etch adhesives were formulated containing 20 wt% HEMA or GDMA. Three-point bending test was used to obtain the elastic modulus of bar-shaped specimens, and water sorption and solubility were attained by ISO-4049 (ISO, 2009) method. Degree of conversion was surveyed by Micro-Raman spectroscopy, and microtensile bond strength was tested after 24 h or 6 months simulated pulpal pressure aging. Statistical analysis was realized with two-way ANOVA and Tukey's test (p < 0.05). RESULTS: GDMA promoted higher elastic modulus to the self-etch adhesive, and GDMA-containing etch-and-rinse adhesive achieved overall lower water sorption and solubility. The degree of conversion was statistically higher for GDMA adhesives than for HEMA etch-and-rinse one. All bond strengths dropped significantly after aging, except that of GDMA self-etch adhesive. The nanoleakage was higher and gaps were found in the interface of HEMA-containing adhesives, which were less present in GDMA equivalents. CONCLUSIONS: GDMA is a feasible hydrophilic dimethacrylate monomer to replace HEMA in simplified adhesives, thereby providing better polymerization, mechanical properties and dentin adhesion as well as lower water uptake and solubility.

Efficacy of new natural biomodification agents from Anacardiaceae extracts on dentin collagen cross-linking.

OBJECTIVES: Several polyphenols from renewable sources were surveyed for dentin biomodification. However, phenols from cashew nut shell liquid (CNSL, Anacardium occidentale) and from Aroeira (Myracrodruon urundeuva) extract have never been evaluated. The present investigation aimed to compare the dentin collagen crosslinking (biomodification) effectiveness of polyphenols from Aroeira stem bark extract, proanthocyanidins (PACs) from grape-seed extract (Vitis vinifera), cardol and cardanol from CNSL after clinically relevant treatment for one minute. METHODS: Three-point bending test was used to obtain the elastic modulus of fully demineralized dentin beams before and after biomodification, whilst color change and mass variation were evaluated after four weeks water biodegradation. Color aspect was assessed by optical images after biodegradation whereas collagen cross-linking was investigated by micro-Raman spectroscopy. Statistical analysis was performed with repeated-measures two way ANOVA and Tukey's test (p<0.05). RESULTS: The increase in elastic modulus after biomodification was in the order cardol>cardanol>aroeira=PACs with cardol solution achieving mean 338.2% increase. The mass increase after biomodification followed the same order aforementioned. Nevertheless, after four weeks aging, more hydrophobic agent (cardanol) induced the highest resistance against water biodegradation. Aroeira and cardol attained intermediate outcomes whereas PACs provided the lower resistance. Tannin-based agents (Aroeira and PACs) stained the specimens in dark brown color. No color alteration was observed with cardol and cardanol treatments. All four agents achieved crosslinking in micro-Raman after one minute application. SIGNIFICANCE: In conclusion, major components of CNSL yield overall best dentin biomodification outcomes when applied for one minute without staining the dentin collagen.

Characterization of Brown spider (Loxosceles intermedia) hemolymph: cellular and biochemical analyses.

This is the first study on the hemolymph from a spider of the Loxosceles genus. These animals are responsible for a great number of envenomation cases worldwide. Several studies on Loxosceles venoms have been published, and the knowledge about the venom and its toxins is considerable, not only regarding the biological and biochemical characterization, but also regarding structural, genetic and phylogenetic approaches. However, the literature on Loxosceles hemolymph is nonexistent. The main goal of the present study was to characterize biochemically the hemolymph content, and especially, to identify its different hemocytes. Moreover, many papers have already shown molecules whose source is the hemolymph and their very interesting activities and biomedical applications, for example, antifungal and antibacterial activities. A 2D-SDS-PAGE of brown spider hemolymph showed approximately 111 spots for pH 3-10 and 150 spots for pH 4-7. A lectin-blotting assay showed that hemolymph carbohydrate residues were similar to those found in venom. Several types of TAG and DAG phospholipids were found in the hemolymph and characterized by HPTLC and mass spectrometry. Four different hemocytes were characterized in Loxosceles intermedia hemolymph: prohemocyte, plasmatocyte, granulocyte and adipohemocyte. This paper opens new possibilities on toxinology, studying an unknown biological material, and it characterizes a source of molecules with putative biotechnological applications.

Leishmania (Leishmania) amazonensis infection in mice treated with FTY720.

In transplantation, parasite diseases are transmitted from the donor, or appear as de novo infections, or activate from a dormant insource as a consequence of immunosuppression. Clinical findings have shown that an intact immune system is crucial to prevent recurrence of Leishmania infection. We used BALB/c and C57BL/6 mice to evaluate the role of FTY720 in leishmaniasis. Mice inoculated with Leishmania (Leishmania) amazonensis were followed over 7 weeks for foot thickness measurements after initiation of FTY720 treatment. After 10 days of treatment, spleen, blood, and the foot were harvested for evaluation. BALB/c showed greater evident foot thickness than C57BL/6 mice. Oral treatment with FTY720 (1 mg/kg/d) over 10 days produced the same outcome. Increases in CD4(+) and CD8(+) T cells were observed after infection; FTY720 treatment was associated with a decrease in CD4(+) T cells only in BALB/c mice, whereas CD8(+) T cells were decreased in both mice strains. CD11b(+) expression decreased after infection with a discrete increase after FTY720 treatment. Lymphopenia was observed among all FTY720-treated mice. In conclusion, we observed that FTY720 produced no worse an outcome as monotherapy in established infections with L (L) amazonensis.