Physicochemical characterization, water sorption and solubility of adhesive systems incorporated with titanium tetrafluoride, and its influence on dentin permeability

Novel resin-based material containing β-tricalcium phosphate nanoparticles for the reduction of dentin permeability

OBJECTIVES

To synthesize and characterize a novel dentin adhesive containing Beta-Tricalcium Phosphate (β-TCP) nanoparticles and test its ability to reduce dentin permeability (dP).

METHODS

Experimental adhesives were prepared by mixing Bis-GMA, TEGDMA, HEMA (50/25/25 wt.%), photo-initiators, and inhibitors. The following groups were tested: Experimental adhesives without β-TCP (Exp.); with 10 wt.% β-TCP (Exp.10 wt.% β-TCP); with 15 wt.% β-TCP (Exp.15 wt.% β-TCP), Scotchbond Multi-Purpose (SBMP) and Clearfil SE Protect Bond (CFPB). Degree of conversion (DC%, 10 and 20 s); Flexural Strength (FS), Knoop Hardness (KHN), and Cell Viability (OD%) tests were performed. dP was evaluated by hydraulic conductance, using human dentin disks (n=12), at three-time intervals: post-EDTA (T0); post-treatment (T1); and post-erosion/abrasion cycling (T2). Data were statistically analyzed (α=0.05).

RESULTS

For all groups, exposure time for 20 s presented a higher DC% than for 10 s. For FS, filled adhesives did not differ from unfilled and from CFPB. Experimental adhesives did not differ among them and showed lower KHN than the commercial products. Cell viability did not differ among adhesives, except Exp. 15 wt.%, which showed lower OD% than Exp., Exp. 10% and, CFPB. For dP, only Exp.10 and 15 wt.% β-TCP did not present difference between the times T1 and T2. After cycling, Exp.10 wt.% β-TCP presented lower permeability than Exp. and CFPB.

CONCLUSIONS

The incorporation of 10 wt.% β-TCP nanoparticles into the resin-based dental material did not affect its mechanical properties and biocompatibility, and promoted the greatest reduction in dentin permeability, sustaining this effect under erosive/abrasive challenges.

CLINICAL SIGNIFICANCE

A novel resin-based dental material containing β-TCP nanoparticles was able to reduce dentin permeability, maintaining its efficacy after erosive/abrasive challenges. The synthesized material did not affect dental pulp cell viability and might be promising for other conditions that require dental remineralization, such as tooth wear and dental caries.

Sepsis-associated neuroinflammation in the spinal cord

Septic patients commonly present with central nervous system (CNS) disorders including impaired consciousness and delirium. Today, the main mechanism regulating sepsis-induced cerebral disorders is believed to be neuroinflammation. However, it is unknown how another component of the CNS, the spinal cord, is influenced during sepsis. In the present study, we intraperitoneally injected mice with lipopolysaccharide (LPS) to investigate molecular and immunohistochemical changes in the spinal cord of a sepsis model. After LPS administration in the spinal cord, pro-inflammatory cytokines including interleukin (IL)-1β, IL-6, and tumor necrosis factor alpha mRNA were rapidly and drastically induced. Twenty-four-hour after the LPS injection, severe neuronal ischemic damage spread into gray matter, especially around the anterior horns, and the anterior column had global edematous changes. Immunostaining analyses showed that spinal microglia were significantly activated and increased, but astrocytes did not show significant change. The current results indicate that sepsis induces acute neuroinflammation, including microglial activation and pro-inflammatory cytokine upregulation in the spinal cord, causing drastic neuronal ischemia and white matter edema in the spinal cord.

Role of 3-Methacryloxypropyltrimethoxysilane in Dentin Bonding

In this study, we aimed to examine the effect of 3-methacryloxypropyltrimethoxysilane (MPS) on dentin collagen and the impact of MPS and 10-methacryloyloxydecyl dihydrogen phosphate (MDP) together and separately on resin-dentin bonding. Eight groups of primers were prepared: control group, MDP, MPS5, MPS5 + MDP, MPS10, MPS10 + MDP, MPS15, and MPS15 + MDP. The potential interaction between MPS and collagen was assessed by molecular dynamics, contact angle measurement, zeta potential measurement, and chemoanalytic characterization using X-ray photoelectron spectroscopy, Raman spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, and ultraviolet-visible spectroscopy. Microtensile bond strength (μTBS) and nanoleakage were evaluated after 24 h or 12 months of water storage. In situ zymography was used to evaluate the enzyme activity at the bonded interface. According to chemoanalytic characterization and molecular dynamics, a weak interaction between MPS and collagen was observed. MPS enhanced the hydrophobicity and negative charge of the collagen surface (P < 0.05). Applying an MDP-containing primer increased μTBS (P > 0.05) and reduced fluorescence after 24 h of water storage. Water storage for 12 months decreased μTBS (P < 0.05) and increased nanoleakage for all groups. MPS conditioning did not change μTBS and nanoleakage after 24 h of water storage or aging. The MPS10 + MDP and MPS15 + MDP groups presented more silver nitrate and μTBS decrease than the MDP group (P < 0.05). These results indicated that MPS had a weak interaction with collagen that enhanced its surface negative charge and hydrophobicity without adversely affecting dentin bonding. However, compared to MDP alone, mixing MDP with MPS impaired their effectiveness and made the dentin bonding unstable.