Physicochemical, Mechanical, and Antimicrobial Properties of Novel Dental Polymers Containing Quaternary Ammonium and Trimethoxysilyl Functionalities.

The aims of this study were to evaluate the physicochemical and mechanical properties, antimicrobial (AM) functionality, and cytotoxic potential of novel dental polymers containing quaternary ammonium and trimethoxysilyl functionalities (e.g., N-(2-(methacryloyloxy)ethyl)-N,N-dimethyl-3-(trimethoxysilyl)propan-1-aminium iodide (AM) and N-(2-(methacryloyloxy)ethyl)-N,N-dimethyl-11-(trimethoxysilyl)undecan-1-aminium bromide (AM)).

Cariogenic potential of sweet flavors in electronic-cigarette liquids.

Background: Most electronic-cigarette liquids contain propylene glycol, glycerin, nicotine and a wide variety of flavors of which many are sweet. Sweet flavors are classified as saccharides, esters, acids or aldehydes. This study investigates changes in cariogenic potential when tooth surfaces are exposed to e-cigarette aerosols generated from well-characterized reference e-liquids with sweet flavors.

Antimicrobial Monomers for Polymeric Dental Restoratives: Cytotoxicity and Physicochemical Properties.

A trend for the next generation of polymeric dental restoratives is to incorporate multifunctional capabilities to regulate microbial growth and remineralize tooth surfaces. Polymerizable 2-(methacryloyloxy)--(2-(methacryloyloxy)ethyl)-,-dimethylethan-1-aminium bromide (IDMA1) and ,'-([1,1'-biphenyl]-2,2'-diylbis(methylene))bis(2-(methacryloyloxy)-,-dimethylethan-1-aminium) bromide (IDMA2), intended for utilization in bi-functional antimicrobial and remineralizing composites, were synthesized, purified with an ethanol-diethyl ether-hexane solvent system, and validated by nuclear magnetic resonance (¹H and C NMR) spectroscopy, mass spectrometry, and Fourier-transform infrared spectroscopy. When incorporated into light-curable urethane dimethacrylate (UDMA)/polyethylene glycol-extended UDMA (PEG-U)/ethyl 2-(hydroxymethyl)acrylate (EHMA) (assigned UPE) resins, IDMAs did not affect the overall resins' hydrophilicity/hydrophobicity balance (water contact angle: 60.

Universal electronic-cigarette test: physiochemical characterization of reference e-liquid.

Background: Despite the rising health and safety concerns of e-cigarettes, a universal e-cigarette testing method is still in its early developmental stage. The aim of this study was to develop an e-liquid Reference Material that can be used to improve accuracy and reproducibility of research results, and advance health risk assessment of e-cigarette products.

Methods: E-liquid Reference Material was developed by purity assessment, gravimetric measurement, homogeneity testing, and stability testing with material and instrument traceability (adopted from ISO 35:2006E).

Simultaneous measurement of polymerization stress and curing kinetics for photo-polymerized composites with high filler contents.

Objectives: Photopolymerized composites are used in a broad range of applications with their performance largely directed by reaction kinetics and contraction accompanying polymerization. The present study was to demonstrate an instrument capable of simultaneously collecting multiple kinetics parameters for a wide range of photopolymerizable systems: degree of conversion (DC), reaction exotherm, and polymerization stress (PS).

Methods: Our system consisted of a cantilever beam-based instrument (tensometer) that has been optimized to capture a large range of stress generated by lightly-filled to highly-filled composites.

Structural and dynamical studies of acid-mediated conversion in amorphous-calcium-phosphate based dental composites.

Objective: To investigate the complex structural and dynamical conversion process of the amorphous-calcium-phosphate (ACP)-to-apatite transition in ACP based dental composite materials.

Methods: Composite disks were prepared using zirconia hybridized ACP fillers (0.4 mass fraction) and photo-activated Bis-GMA/TEGDMA resin (0.

Sensory ability in the narwhal tooth organ system.

The erupted tusk of the narwhal exhibits sensory ability. The hypothesized sensory pathway begins with ocean water entering through cementum channels to a network of patent dentinal tubules extending from the dentinocementum junction to the inner pulpal wall. Circumpulpal sensory structures then signal pulpal nerves terminating near the base of the tusk.

Long-term mechanical durability of dental nanocomposites containing amorphous calcium phosphate nanoparticles.

Half of all dental restorations fail within 10 years, with secondary caries and restoration fracture being the main reasons. Calcium phosphate (CaP) composites can release Ca and PO(4) ions and remineralize tooth lesions. However, there has been no report on their long-term mechanical durability.

Analyses of a cantilever-beam based instrument for evaluating the development of polymerization stresses.

Objective: This investigation was to generate (1) guidelines for designing a tensometer that satisfies the necessary accuracy and sensitivity requirements for measuring polymerization stress (PS), and (2) a formula for calculating PS. Polymerization stress remains one of the most critical properties of polymeric dental materials, yet methods that can accurately quantify PS have been limited in part due to the complexity of polymerization, and in part due to the instrumentation itself.

Method: In this study, we performed analytical and finite element analyses on a cantilever-beam based tensometer that is used to evaluate shrinkage stresses during the polymerization of dental restorative composites.

Polymerization stress development in dental composites: Effect of cavity design factor.

The objective of the study was to assess the effect of the cavity design factor (C-factor) on polymerization stress development (PSD) in resin composites. An experimental resin (BT resin) was prepared, which contained 2,2-bis[p-(2'hydroxy-3'-methacryloxypropoxy)phenylene]propane (B) and triethylene glycol dimethacrylate (T) in 1:1 mass ratio, and an activator for visible light polymerization. Also an experimental composite with demonstrated remineralizing potential was formulated by inclusion into the BT resin of zirconia-hybridized amorphous calcium phosphate (ACP) filler at a mass fraction of 40 % (BT/ACP composite).

Adhesive Bonding to Dentin Improved by Polymerizable Cyclodextrin Derivatives.

The objective of this work was to determine bonding characteristics of a hydrophilic monomer formulation containing polymerizable cyclodextrin derivatives. The hypothesis was that a formulation containing hydrophilic cross-linking diluent comonomers and cyclodextrins with functional groups attached by hydrolytically stable ether linkages could form strong adhesive bonds to dentin. The previously synthesized polymerizable cyclodextrin derivatives were formulated with sorbitol dimethacrylate, methacrylic acid and phenylbis(2,4,6-trimethylbenzoyl) phosphine oxide photoinitiator.

Magnetic resonance microscopy of collagen mineralization.

A model mineralizing system was subjected to magnetic resonance microscopy to investigate how water proton transverse (T(2)) relaxation times and magnetization transfer ratios can be applied to monitor collagen mineralization. In our model system, a collagen sponge was mineralized with polymer-stabilized amorphous calcium carbonate. The lower hydration and water proton T(2) values of collagen sponges during the initial mineralization phase were attributed to the replacement of the water within the collagen fibrils by amorphous calcium carbonate.

Dentin adhesion and microleakage of a resin-based calcium phosphate pulp capping and basing cement.

An experimental resin-based bioactive calcium phosphate cement, intended as a pulp capping and basing material, was evaluated for dentin shear bond strength and microleakage. The interfacial morphology was examined by scanning electron microscopy (SEM). For microleakage, dentin cavities without (Group A) or after (Group B) acid etching were restored with the calcium phosphate cement.

Effect of thermal cycling on whisker-reinforced dental resin composites.

The mechanical properties of dental resin composites need to be improved in order to extend their use to high stress-bearing applications such as crown and bridge restorations. Recent studies used single crystal ceramic whiskers to reinforce dental composites. The aim of this study was to investigate the effects of thermal cycling on whisker-reinforced composites.

Three-body wear of dental resin composites reinforced with silica-fused whiskers.

Objective: Recent studies used silica-fused whiskers to increase the strength and toughness of resin composites. This study investigated the three-body wear of whisker composites. It was hypothesized that the whisker composites would be more wear resistant than composites reinforced with fine glass particles, and the whisker-to-silica filler ratio would significantly affect wear.

Investigations of electrospray sample deposition for polymer MALDI mass spectrometry.

In the interest of a more thorough understanding of the relationship between sample deposition technique and the quality of data obtained using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry, details of the electrospray (ES) process of sample deposition are investigated using a number of techniques. Sample morphology was observed with scanning electron microscopy (SEM) and atomic force microscopy (AFM), while matrix-enhanced secondary ion mass spectrometry (MESIMS) monitored surface coverage. Electrospray deposition reduces the analyte segregation that can occur during traditional dried droplet deposition for MALDI.

Effects of different whiskers on the reinforcement of dental resin composites.

Objective: Whiskers were recently used to reinforce dental composites to extend their use to large stress-bearing restorations. The aim of this study was to investigate the effects of different types of whiskers on composite properties.

Methods: Silicon nitride and silicon carbide whiskers were each mixed with silica particles at whisker/silica mass ratios of 0:1, 1:5, 1:2, 1:1, 2:1, 5:1, and 1:0, and thermally treated.

Microtensile bond strength of thermally stressed composite-dentin bonds mediated by one-bottle adhesives.

Purpose: To evaluate the effects of thermally stressing composite-dentin bonds in teeth subjected to a modified microtensile bond test that allowed application of two bonding agents side-by-side to the same tooth.

Materials And Methods: Extracted human molars with a slot dissecting the occlusal dentin surface were conditioned and primed on one side with Prime & Bond NT (PBNT) and Prime One Mirage (P-One) on the other side. The composite was light-cured onto the surface.