A Preliminary Volterra Lotka Model Analysing Cancer, Intracellular Parasite, and Immune Cells Interaction

In this paper, we investigate the dynamics of immune and tumor cell densities in the presence of a parasite using the prey- predator Volterra-Lotka model in a biological system, assuming that the parasite is either a down or up-regulator of the induced immune cells. Thus, we analysed the model for equal and non equal initial conditions and report their impact on the populations growth

Antibacterial effect of titanium dioxide-doped phosphate glass microspheres filled total-etch dental adhesive on S. mutans biofilm

Purposeto improve the antibacterial action of a two-step total-etch dental adhesive by using titanium dioxide-doped phosphate glass microspheres (GMs) without affecting its penetration ability.Materials and MethodsFive and 10 wt% of APTES silanized [surface treated with 3-Aminopropyltriethoxysilane (APTES)] and non-silanized GMs have been used as a filler to AdperTM Single Bond 2 Refill. The morphology, chemistry and ζ - potential of GMs have been investigated using scanning electron microscopy, Fourier transform infra-red (FTIR) spectroscopy and Zeta-sizer respectively. The chemistry and antibacterial action of filled adhesive have been investigated using FTIR and nitrocellulose filter membranes (NFM) S. mutans biofilm model respectively. The number of colony forming units (CFU) per NFM was considered. The contact angle and microtensile bond strength of adhesives to mid-coronal dentin, as a measure of its penetration ability, have been investigated using a Drop Shape Analyzer and microtensile testing machine respectively. AdperTM Single Bond 2 Refill was used as a control.ResultsThe size of GMs varied from 60-200 μm. The silanization process was confirmed by reduction in ζ-potential [-7 (±2) mV] and the presence of amide (1500-1600 cm-1), C-N (1380 cm-1), Si-O-Si (1096 cm-1) and Si-O-C (780 cm-1) peaks. Incorporation of GMs had no adverse effect on monomer conversion. All tested adhesives including the control showed significantly higher antibacterial action (∼5-7 log10 reduction in CFU) than the NFM control. All filled adhesives showed significantly higher antibacterial action (∼1-2 log10 reduction in CFU) than the control adhesive. The non-silanized GMs filled adhesives showed the highest antibacterial action against S. mutans biofilm formation. The presence of silanized GMs did not affect the wetting but increased the microtensile bond strength of the adhesive to dentin.ConclusionGlass microsphere modified adhesives could be promising to reduce the possibility of recurrent caries around restorations

Bonding of Clear Aligner Composite Attachments to Ceramic Materials: An In Vitro Study

Background: We aim to evaluate the effect of surface conditioning, bonding agents and composite types on surface roughness (SR) and shear bond strength (SBS) of clear aligner composite attachments bonded to ceramics. Methods: One hundred and eighty IPS e.max CAD specimens were prepared. For SR, 60 specimens were divided according to surface conditioning (n = 15) into four groups: control, 9.6% hydrofluoric acid (HFA), 37% phosphoric acid (PhA), air abrasion (AA). SR was measured using a Profilometer and Atomic Force Microscopy. For SBS, 120 specimens were divided according to conditioning methods (n = 40) (9.6% HFA and 37% PhA or AA), then according to bonding agents (n = 20) (Assure universal bond (AUB) or Single bond universal (SBU)) and then according to composite type (n = 10): Filtek™ Z350 and Filtek™ Z350 XT flowable composite. SBS was measured using Instron testing machine. Descriptive and group comparison were calculated (p p p > 0.05). AUB had higher SBS than SBU (p p < 0.01). Conclusion: The combination of AA, AUB, and Filtek Z350 produced the highest SBS, followed by HFA, AUB, and Filtek Z350

Cross-linked dry bonding: A new etch-and-rinse technique

Objective To determine if acid-etched, cross-linked dentin can be dehydrated without lowering bond strength below that of cross-linked wet-bonded dentin in vitro. Methods Using extracted human third molars, control acid-etched dentin was bonded with Single Bond Plus, using either the wet- or dry-bonding technique. Experimental acid-etched dentin was treated with 5\ua0mass% grape seed extract (GSE) in different solvents for 1\ua0min before undergoing wet vs dry resin-dentin bonding with Single Bond Plus. Completely demineralized dentin beams were treated with 5% GSE for 0, 1 or 10\ua0min, before measuring stiffness by 3-point flexure. Other completely demineralized beams were treated similarly and then incubated in buffer for 1 week to measure the collagen solubilization by endogenous dentin proteases. Results 24\ua0h microtensile bond strengths (\u3bcTBS) in wet and dry controls were 53.5\ua0\ub1\ua03.6 and 9.4\ua0\ub1\ua01.8\ua0MPa, respectively (p\ua0\ua00.05). Cross-linking demineralized dentin with 5% GSE increased stiffness of dentin and decreased collagen degradation (p\ua0<\ua00.05). Significance 5% GSE pretreatment of acid-etched dentin for 1\ua0min permits the dentin to be completely air-dried without lowering bond strength

Effects of particle distribution and calculation method on results of nano-indentation technique in heterogeneous nanocomposites-experimental and numerical approaches

This study aims to investigate the effects of two testing parameters on the results of the nano-indentation experiment in the heterogeneous particle reinforced composites: (1) the particle distribution pattern, and (2) the methods for calculating the residual projected contact area of the sample under the indenter. For this purpose, several nano-indentation experiments were performed by using Berkovich indenter on the specimens prepared from Filtek Z350 XT dental nanocomposite as a particle reinforced composite with a volume fraction of 63.3 percent. Then, the nano-indentation procedure on the dental nanocomposite was simulated using the finite element (FE) method. In the FE simulation, several representative volume elements (RVEs) of the nanocomposite were modeled by modifying the Lubachevsky-Stillinger algorithm to distribute particles randomly with a volume fraction of more than 50 percent in a cubic volume. The hardness and elastic modulus of the nanocomposite were calculated from the results of the nano-indentation experiment and the simulation. In these calculations, the projected contact area of the indenter on the specimen was obtained using two different approaches of the Oliver-Pharr method and direct measurement of the area. The results indicated that the distribution of particles around the indenter has significant effects on the nano-indentation results. According to the simulation results, the heterogeneity of the material causes the projected contact area of the indenter on the sample to distort from its equilateral triangle shape, which is assumed in the Oliver-Pharr method. Therefore, the method of direct measurement of the indenter projected contact area on the specimen is proposed to obtain more precise results from the nano-indentation test on heterogeneous materials