Acid Primer Research Articles

Morphological and molecular characterization of L-methioninase producing Aspergillus species

Six species of L-methioninase producing Aspergillus species, isolated from Egyptian soil, were selected for comprehensive morphotypic and molecular characterization. Based on morphological and physiological features, these isolates were identified as Aspergillus flavipes , Aspergillus carneus , Aspergillus flavus , Aspergillus tamari , Aspergillus oryzae , and Aspergillus parasiticus . Regarding to the maximum enzyme productivity by A. flavipes , it was selected as authentic strain for ribosomal ribonucleic acid (rRNA) primer design. Using primer combinations for 18S rRNA and internal transcribed spacers (ITS)1 amplification, these isolates gave the same polymerase chain reaction (PCR) amplicon size, revealing the relative molecular identity. Moreover, using ITS2 primers, among the six isolates, Aspergillus flavipes EK and A. carneus displayed PCR products on agarose gel, approving the actual morphological and biochemical similarities of these two isolates, A. flavipes group. By sequencing of ITS1-5.8S-ITS2 region, blasting and alignment from the data base, A. flavipes EK showed a typical identity to gene bank deposited A. flavipes isolates. The rRNA sequence of A. flavipes EK was deposited to genbank under accession number JF831014. Key words: Aspergillus , morphological descriptions, 18 S rRNA, internal transcribed spacers (ITS) regions.

Effect of heat treatment of dental zirconia ceramic treated with three different primers on the bonding durability of resin cement

Establishing a durable bond with dental zirconia ceramic remains difficult. This study investigated the effect of heat treatment of primer-coated dental zirconia on the bonding durability of resin cement to the zirconia. Each of three types of primers (silane primer, acidic monomer-containing primer, and silane/acidic monomer containing two-component primer) was applied to sandblasted zirconia surfaces. For subsequent heat treatment, half were then put in a furnace for 60 min at 150 °C. All specimens were bonded with resin cement and aged using thermocycling (0, 5,000, and 20,000 cycles) prior to a shear test. The surface energy parameters of the zirconia were also calculated from the contact angle measurements based on the acid-base theory. The heat treatment enhanced the bonding durability of the zirconia pre-treated with the silane primer and the acidic monomer-containing one, the shear test and Weibull analysis results showed that the former performed better than the latter. In contrast, the twocomponent primer-coated zirconia showed poor bonding durability after the heat treatment. The bonding performance was related to the surface characteristics of the zirconia. Thus, we suggest that heat treatment of zirconia pretreated with silane primer effectively improves bonding durability with resin cement. Open image in new window

Updates in Immunoassays: Virology

Virus identification is a challenge to the clinical microbiologist since growing viruses in traditional cell culture is labor intensive, time consuming, and subject to contamination. The advent of rapid and automated immunoassays has eliminated this problem by generating positive results in minutes to hours. For example, testing for infectious mononucleosis can yield a positive result in 3-8 minutes as seen with the Beckman Coulter, Inc. ICON Mono test or in 5-15 minutes with the MONO Mononucleosis Rapid Test Device marketed by ACON Laboratories, Inc. Fully automated immunoassay analyzers provide fast, accurate, sensitive results that aid in a prompt and accurate diagnosis for the patient. Turnaround times are shortened, allowing for timely medical intervention and treatment. The priority in any hospital or medical facility is to treat the patient as quickly and appropriately as possible. By using immunoassays, clinical laboratory professionals are able to report out correct results in a timely manner, ensuring overall positive patient outcomes and improved quality of healthcare.

Adhesive bonding of Ti-6Al-7Nb alloy and component metals with acidic primers and a tri-n-butylborane initiated resin.

To evaluate the effects of acidic functional monomers on the bond strength and durability of an acrylic resin joined to Ti-6Al-7Nb alloy and component metals. Disk specimens of two different sizes (10 and 8 mm in diameter and 2.5 mm in thickness) were prepared from uncast Ti-6Al-7Nb alloy, titanium, aluminum, and niobium. The specimens were ground with abrasive paper and divided into 8 groups: unprimed control, primed with Acryl Bond, Alloy Primer, All Bond II Primer B, Estenia Opaque Primer, M.L. Primer, MR. Bond, and Super-Bond Liquid. The disks were bonded with tri-n-butylborane (TBB)-initiated acrylic resin, and shear bond strengths were determined both before and after thermocycling. The Alloy Primer and Estenia Opaque Primer agents, which contain a hydrophobic phosphate monomer (MDP), and Super-Bond Liquid demonstrated a durable bond with Ti-6Al-7Nb alloy. MDP was also effective in bonding Ti, Al, and Nb. The two primers containing MDP were effective for treating Ti-6Al-7Nb alloy and Ti. Al and Nb showed bonding behavior similar to Ti-6Al-7Nb alloy and Ti when the two metals were treated with acidic primers and bonded with the TBB-initiated acrylic resin.

Effect of acidic monomers on bonding to SUS XM27 stainless steel, iron, and chromium with a tri-n-butylborane-initiated acrylic resin.

To evaluate the effects of carboxylic and phosphate functional monomers on the bond strength and durability of an acrylic resin joined to a magnetizable stainless steel and its component metals. Disk specimens (10 and 8 mm in diameter and 2.5 mm thick) were prepared from SUS XM27 stainless steel, high-purity iron, and chromium metals. The specimens were ground with abrasive paper, and divided into an unprimed control group and 4 groups primed with: 1. Alloy Primer (thione and phosphate); 2. Estenia Opaque Primer (phosphate); 3. Mr. Bond (aliphatic carboxylic acid); or 4. Super-Bond C&B Liquid (aromatic carboxylic anhydride). The disks were bonded with tri-n-butylborane (TBB)-initiated resin, and the shear bond strengths were determined both before and after thermocycling (20,000 X, 5°C - 55°C). The debonded surfaces were analyzed using Xray diffraction (XRD). The Alloy Primer and Estenia Opaque Primer materials containing 10-methacryloyloxydecyl dihydrogen phosphate (MDP) effectively bonded the steel (30.3 to 32.4 MPa) and iron (33.6 to 34.8 MPa), whereas the four acidic primers bonded chromium (24.6 to 32.3 MPa). X-ray diffractometry detected corroded iron at the debonded interface. Bearing in mind the limitations of the present study, the use of two primers with MDP is recommendable for bonding SUS XM27 steel with TBB-initiated resin. Iron was considered to be a corrosive factor at the adhesive interface, although the associated bonding characteristics were adequate.

Avaliação da resistência ao cisalhamento de dois compósitos colados em superfície condicionada com primer autocondicionante

OBJETIVO: o objetivo desse estudo foi avaliar a resistência ao cisalhamento e o índice de remanescente de adesivo (IRA) dos compósitos Eagle Bond e Orthobond em superfície de esmalte condicionada com Transbond Plus Self-Etching Primer. MÉTODOS: foram utilizados 75 incisivos inferiores permanentes bovinos divididos em cinco grupos (n=15). Nos grupos 1, 2 e 4, as colagens foram realizadas com Transbond XT, Orthobond e Eagle Bond, respectivamente, seguindo as recomendações dos fabricantes. Nos grupos 3 e 4, antes da colagem com o Orthobond e o Eagle Bond, respectivamente, a superfície dentária foi condicionada com o ácido-primer Transbond Plus Self-Etching Primer. Após a colagem, realizou-se o ensaio de cisalhamento de toda amostra à velocidade de 0,5mm/min em máquina Instron de ensaios mecânicos. RESULTADOS:os resultados (em MPa) mostraram não haver diferenças estatisticamente significativas entre os grupos 1, 2, 3 e 5 (p>0,05). Entretanto, esses grupos foram estatisticamente superiores ao grupo 4 (p<0,05). Os resultados do IRA (Índice de Remanescente de Adesivo) evidenciaram maior número de fraturas na interface braquete/compósito nos grupos 1, 2, 3 e 5.

Comparison of the duplex-destabilizing effects of nucleobase-caged oligonucleotides

Nucleobase-caged oligonucleotide residues have photolabile "caging groups" that prevent the formation of Watson-Crick base pairs until the unmodified nucleobase is restored in a photolysis event. This principle can be used to put a growing variety of powerful nucleic acid-based applications under the precise spatiotemporal control using light as an addressing mechanism. Examples for applications include light control of transcription, RNAi, nucleic acid folding, primer extension, and restriction endonuclease as well as DNAzyme, aptamer, and antisense activity. However, a comparison of the duplex-destabilization properties of the various caged residues that have been used up to date and rules for achieving a maximal duplex destabilization with a minimum amount of modified residues are still missing. We present both a comparison of the duplex-destabilizing capabilities of various nucleobase-caged residues and address the question of influence on neighboring base pairs.

Adhesive bonding of zirconia with single-liquid acidic primers and a tri-n-butylborane initiated acrylic resin.

The purpose of the current study was to evaluate the effect of acidic primers on the bond strength and durability of an acrylic resin luting agent to zirconia. Disk specimens were fabricated from zirconia partially stabilized with yttrium oxide (Katana, Noritake Dental Supply). The disks were treated with one of the following acidic primers: Acryl Bond (Shofu), All Bond II Primer B (Bisco), Alloy Primer (Kuraray), Estenia Opaque Primer (Kuraray), Eye Sight Opaque Primer (Kanebo), M.L. Primer (Shofu), MR. Bond (Tokuyama Dental), or Super-Bond Liquid (Sun Medical). Unprimed specimens served as the control. The disks were bonded with a tri-n-butylborane (TBB)-initiated acrylic resin. Shear bond strengths were determined both before and after 10,000 thermocycles (5°C and 55°C, 1 min dwell time each). The pre-thermocycling bond strength ranged from 0.7 MPa to 30.8 MPa, whereas post-thermocycling bond strength varied from 0.3 MPa to 17.6 MPa. The significantly highest post-thermocycling bond strength was obtained when using the Alloy Primer and Estenia Opaque Primer agents. Within the limitations of the current experiment, it can be concluded that application of either the Alloy Primer or the Estenia Opaque Primer, both of which contain 10-methacryloyloxydecyl dihydrogen phosphate (MDP), is recommended for bonding the Katana zirconia material with TBB-initiated acrylic resin.

Review of matrix metalloproteinases' effect on the hybrid dentin bond layer stability and chlorhexidine clinical use to prevent bond failure.

This review describes the relationship between dentin collagen hybrid bond layer degradation and the Matrix Metalloproteinases (MMPs) after their release by acid etch and rinse adhesives and self etching bonding adhesives that can reduce the bond stability over time. MMP-2, MMP-8 and MMP-9 are indicated as the active proteases that breakdown the collagen fibrils in the hybrid bond layer. Phosphoric acid in the acid etch and rinse bonding process and acid primers in the self etch process are implicated in the release of these proteases and their activation by several non-collagen proteins also released from dentin by the etching. MMPs are released in saliva by salivary glands, by cells in the gingival crevices to crevicular fluid and by pulpal odontoblasts cells to the dentinal fluids. These sources may affect the hybrid layer also. Evidence of the bond strength deterioration over time and the ability of Chlorhexidine to prevent bond deterioration by inhibiting MMP action are discussed. Dentin Bonding procedure utilizing Chlorhexidine for different application times and concentrations are being developed. The application of 2% Chlorhexidine to the phosphoric acid etch surface after rinsing off the acid is the only procedure that has been clinically tested for a longer period of time and shown to prevent bond strength degradation so far. The adoption of this procedure is recommended as means of improving bond stability at this time.

Influence of Blood Contamination on Bond Strength of a Self-Etching System

To detect the influence of blood contamination (BC) on the bond strength (BS) of a self-etching bonding system (SES) to enamel and dentine. 25 human molars were longitudinally sectioned on the mesio-distal axis in order to obtain 50 specimens, which were embedded in acrylic resin. At first, the specimens were ground to expose a flat surface of enamel, and a bond strength test was performed. Afterwards, the samples were ground again in order to obtain a flat surface of dentine. Ten groups (total: n=100) were assigned according to substrate (enamel and dentine), step in the bonding sequence when contamination occurred (before the acidic primer and after the bonding resin), and contamination treatment (dry or rinse and dry procedure). Fresh human blood was introduced either before or after SES application (Clearfil SE Bond) and treated with air drying, or by rinsing and drying following application. Composite resin (Filtek Z-250,3M ESPE) was applied as inverted, truncated cured cones that were debonded in tension. The mean tensile BS values (MPa) for enamel/dentine were 19.4/23.0 and 17.1/10.0 for rinse-and-dry treatment (contamination before and after SES, respectively); while the measurements for the dry treatment, 16.2/23.3 and 0.0/0.0 contamination before and after SES, respectively. It was determined that blood contamination impaired adhesion to enamel and dentine when it occurred after bond light curing. Among the tested contamination treatments, the rinse-and-dry treatment produced the highest bond strength with BC after SES application, but it was not sufficient to recover the BS in the contamination-free group.

Influence of ceramic (feldspathic) surface treatments on the micro-shear bond strength of composite resin

To test the null hypothesis that surface treatment has no influence on the micro-shear bond strength between orthodontic composite resin cement and ceramics (feldspathic porcelain). Circular specimens of feldspathic porcelain were fabricated and randomly divided into six groups: (1) no treatment; (2) treatment with a mixture of acidic primer and silane agent for 20 seconds; (3) etching with 9.5% hydrofluoric acid; (4) etching with 9.5% hydrofluoric acid and coating with a mixture of acidic primer and silane agent for 20 seconds; (5) airborne-particle abrasion with 50-mum aluminum oxide; and (6) airborne-particle abrasion and coating with a mixture of acidic primer and silane agent for 20 seconds. The porcelain disks were then bonded to resin cylinders with composite resin cement. A micro-shear bond test was carried out to measure the bond strength. Moreover, each ceramic surface was observed morphologically by scanning electron microscopy. One-way analysis of covariance was used to compare the groups for differences in micro-shear bond strength. The mean micro-shear bond strength varied as a function of surface treatment. It ranged from 3.7 to 20.8 MPa. The highest values for micro-shear bond strength were found when the surface was acid-etched with hydrofluoric acid and coated with silane. On the other hand, the control group (no treatment) had significantly lower micro-shear bond strength than all the other groups. The null hypothesis that the surface treatment has no influence on the micro-shear bond strength of orthodontic composite resin was rejected. The bond strength between ceramics and orthodontic resin cement is affected by the ceramic surface treatment. The bond failure was of the adhesive type, except with the hydrofluoric acid + silane group, where it was a cohesive bond failure.

Synthesis of bis(3-{[2-(allyloxy)ethoxy]methyl}-2,4,6-trimethylbenzoyl)(phenyl)phosphine oxide – a tailor-made photoinitiator for dental adhesives

Because of the poor solubility of the commercially available bisacylphosphine oxides in dental acidic aqueous primer formulations, bis(3-{[2-(allyloxy)ethoxy]methyl}-2,4,6-trimethylbenzoyl)(phenyl)phosphine oxide (WBAPO) was synthesized starting from 3-(chloromethyl)-2,4,6-trimethylbenzoic acid by the dichlorophosphine route. The substituent was introduced by etherification with 2-(allyloxy)ethanol. In the second step, 3-{[2-(allyloxy)ethoxy]methyl}-2,4,6-trimethylbenzoic acid was chlorinated. The formed acid chloride showed an unexpected low thermal stability. Its thermal rearrangement at 180 °C resulted in a fast formation of 3-(chloromethyl)-2,4,6-trimethylbenzoic acid 2-(allyloxy)ethyl ester. In the third step, the acid chloride was reacted with phenylphosphine dilithium with the formation of bis(3-{[2-(allyloxy)ethoxy]methyl}-2,4,6-trimethylbenzoyl)(phenyl)phosphine, which was oxidized to WBAPO. The structure of WBAPO was confirmed by 1H NMR, 13C NMR, 31P NMR, and IR spectroscopy, as well as elemental analysis. WBAPO, a yellow liquid, possesses improved solubility in polar solvents and shows UV–vis absorption, and a high photoreactivity comparable with the commercially available bisacylphosphine oxides. A sufficient storage stability was found in dental acidic aqueous primer formulations.

Effect of 2% chlorhexidine application on microtensile bond strength of resin composite to dentin using one-step self-etch adhesives

The latest development in dental adhesion is basedon simplification and a reduced application time. Thefirst self-etch adhesives were composed of two solu-tions, an acidic primer and bonding resin. Recently,many clinicians have shifted to one-step self-etchsystems (all-in-one adhesives), in which the manu-facturers have attempted to incorporate all the pri-mary components of an adhesive system (etchant,primer, and bonding resin) into a single solution.

Effect of acidic primers on adhesive bonding of tri-n-butylborane initiated adhesive resin to alumina

The present study was conducted to evaluate the effect of acidic primers on adhesive bonding to sintered alumina. Alumina disk specimens were primed with one of the following acidic materials: Acryl Bond, All Bond II Primer B, Alloy Primer, Estenia Opaque Primer, Eye Sight Opaque Primer, M.L. Primer, MR. Bond, and Super-Bond Liquid. The disks were bonded with an adhesive resin (Super-Bond) initiated with a tri-n-butylborane (TBB) derivative, and bond strengths were determined. Average bond strength before thermocycling varied from 42.9 to 44.3 MPa, whereas post-thermocycling bond strength ranged from 22.0 to 42.8 MPa. Of the nine groups assessed, reduction of bond strength after thermocycling was not significant in three: Alloy Primer, Estenia Opaque Primer, and Eye Sight Opaque Primer. It can be concluded that phosphate-based primers are recommended for bonding sintered alumina with Super-Bond resin.

Mechanism of Inhibition of HIV-1 Reverse Transcriptase by 4′-Ethynyl-2-fluoro-2′-deoxyadenosine Triphosphate, a Translocation-defective Reverse Transcriptase Inhibitor

Nucleoside reverse transcriptase inhibitors (NRTIs) are employed in first line therapies for the treatment of human immunodeficiency virus (HIV) infection. They generally lack a 3'-hydroxyl group, and thus when incorporated into the nascent DNA they prevent further elongation. In this report we show that 4'-ethynyl-2-fluoro-2'-deoxyadenosine (EFdA), a nucleoside analog that retains a 3'-hydroxyl moiety, inhibited HIV-1 replication in activated peripheral blood mononuclear cells with an EC(50) of 0.05 nm, a potency several orders of magnitude better than any of the current clinically used NRTIs. This exceptional antiviral activity stems in part from a mechanism of action that is different from approved NRTIs. Reverse transcriptase (RT) can use EFdA-5'-triphosphate (EFdA-TP) as a substrate more efficiently than the natural substrate, dATP. Importantly, despite the presence of a 3'-hydroxyl, the incorporated EFdA monophosphate (EFdA-MP) acted mainly as a de facto terminator of further RT-catalyzed DNA synthesis because of the difficulty of RT translocation on the nucleic acid primer possessing 3'-terminal EFdA-MP. EFdA-TP is thus a translocation-defective RT inhibitor (TDRTI). This diminished translocation kept the primer 3'-terminal EFdA-MP ideally located to undergo phosphorolytic excision. However, net phosphorolysis was not substantially increased, because of the apparently facile reincorporation of the newly excised EFdA-TP. Our molecular modeling studies suggest that the 4'-ethynyl fits into a hydrophobic pocket defined by RT residues Ala-114, Tyr-115, Phe-160, and Met-184 and the aliphatic chain of Asp-185. These interactions, which contribute to both enhanced RT utilization of EFdA-TP and difficulty in the translocation of 3'-terminal EFdA-MP primers, underlie the mechanism of action of this potent antiviral nucleoside.

Recent developments in nucleic acid based techniques for use in rumen manipulation

Nucleic acid-based techniques which can be used to characterise complex microbial communities without incubation are now being employed regularly in ruminant nutrition studies. Conventional culture-based methods for enumerating rumen microorganisms (bacteria, archaea, protozoa, and fungi) have been superseded and are now used mainly to obtain pure isolates of novel organisms and reference strains that are required for the development and validation of the nucleic acid approaches. These reference strains are also essential for physiological studies of the lifestyle of the organisms as well as sources of genomic DNA and RNA that can be analysed for functional gene activity. The foundation of the molecular ecology techniques is 16S/18S rDNA sequence analysis which has provided a phylogenetically based classification scheme for enumeration and identification of microbial community members. The use of this marker gene in assays involving the use of single nucleic acid probes or primer sets is rapidly evolving to high throughput approaches such as microarray analysis and new generation sequencing technologies. While these analyses are very informative for determining the composition of the microbial community and monitoring changes in population size, they can only infer function based on these observations. The focus of nucleic acid research is now shifting to the functional analysis of the ecosystem which involves the measurement of functional genes and their expression in the predominant or specific members of the rumen microbial community. Functional gene studies are less developed than 16S rDNA-based analysis of community structure. Also for gene expression studies there are inherent problems involved in extracting high quality RNA from digesta, and priming cDNA synthesis from bacterial mRNA. This paper reviews nucleic acid based molecular methods which have recently been developed for studying the structure and function of rumen microbial communities.

An SEM evaluation of conditioned and bonded enamel following carbamide peroxide bleaching and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) treatment

The study aimed to evaluate, (a) the surface morphology of acid etched/conditioned enamel following carbamide peroxide bleaching with/without casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) (Tooth Mousse (MI Paste); GC Corp., Tokyo, Japan) treatment; and b) the nature of the bonded resin-enamel interfaces formed with a self-etching primer adhesive. Twenty-four human adult molars were each sectioned into four, the specimens divided and treated according to four experimental groups: 1, no treatment; 2, 16% carbamide peroxide bleaching; 3, CPP-ACP paste; 4, bleaching and CPP-ACP paste. A self-etching primer adhesive (Clearfil SE Bond, CSE) was used. The specimens were further divided into four subgroups for etching/conditioning: A, CSE Primer only; B, 30-40% phosphoric acid and CSE primer; C, 15% EDTA and CSE primer; D, 20% polyacrylic acid and CSE primer. Bonded specimens were also prepared. The morphology of the etched/conditioned enamel surfaces and polished resin-enamel interfaces of the bonded specimens were observed by field-emission scanning electron microscopy (FE-SEM). Treatment with CPP-ACP did not inhibit phosphoric acid etching of enamel. Poorly defined enamel etch patterns were observed with the other conditioners in all the groups. The morphology of the bonded resin-enamel interfaces observed on FE-SEM for each acid etching/conditioning subgroup was similar in all the experimental groups, except after bleaching. Resin infiltration into enamel was observed with prior phosphoric acid etching and polyacrylic acid conditioning and was unaffected by experimental group treatments. The use of a CPP-ACP paste with or without prior bleaching did not inhibit enamel etching. Enamel etching/conditioning may help improve bonding efficiency of the self-etching primer adhesive after CPP-ACP treatment.

Influence of Different Primer Application Times On Bond Strength of Self-etching Adhesive Systems to Unground Enamel

This study evaluated the influence of increasing the application time of acid primer on the bond strength of one- and two-step self-etching systems to unground enamel. Thirty-two human third molars were used in this study. Additionally, four self-etching adhesive systems: Clearfil SE Bond (Kuraray), AdheSE (Ivoclar-Vivadent), Futurabond NR (Voco) and One Up Bond F Plus (J Morita) were used in two conditions according to each manufacturer's recommendations and using double the application time of the primer recommended by the manufacturers. The teeth were randomly separated into groups and sectioned in their central region in the buccal-lingual direction perpendicular to their long axes, using a double-faced diamond disk. A 6-mm high block was then made with Rok (SDI) resin composite on the mesial and distal faces of each tooth. The samples were then serially sectioned from the resin composite in the occlusal-gingival and buccal-lingual directions at a distance of 1 mm between cuts using a high concentration diamond disk adapted to a precision cutter. The microtensile test was performed in a universal test machine at a speed of 0.5 mm/minute. The fractured specimens were analyzed by scanning electronic microscopy to determine failure modes. The data obtained were submitted to ANOVA and the Tukey Kramer tests. There was no statistically significant difference among the adhesive systems and primer application times. Failure modes varied among the groups and were influenced by the increase in acid primer application time.

Can the Method of Primer Application Influence Adhesion to Er:YAG-laser Irradiated Dentin?

The aim of this study was to evaluate how cavity preparation and primer application methods influence the adhesion of composite resin to dentin using a self-etching system. Forty-eight extracted, sound human molars were divided into six groups (n=8) according to the method used for the surface preparation of the teeth (#600-grit paper disc, diamond bur, and Er:YAG laser) and the primer application method utilized (active or passive). Following the adhesive procedure using a self-etching system, 5 mm high composite buildups were created with Z-250 composite resin. After storage in water at 37 degrees C for 24 hours, the specimens were vertically sectioned into serial 1 mm2 sticks and tested for microtensile strength (micro-TBS). Nine additional molars were prepared for morphological analysis using scanning electron microscopy (SEM). Statistical analysis showed surface preparation technique (p < 0.00) and primer application methods (p < 0.001) do influence bond strength of the self-etching system tested. The best adhesion was achieved with specimens having the dentin ground with sandpaper followed by those ground with diamond burs. The worst bonding was obtained with Er:YAG laser ablated dentin. The active primer application method increased bonding performance compared to the passive method. Within the limitations of the study, it can be stated surface treatment can influence the bond strength of the self-etching system tested and the active primer application method is more effective in achieving success in bonding to dentin compared with the passive application method. Clinicians should use the active application method to apply a mild acidic self-etching primer along with an appropriate tooth surface preparation to facilitate the bond strength between dentin and composite resin.

High density hydrophilic and hydrophobic brush coatings using a polymeric primer layer

Polymer brush coatings, consisting of polymer chains covalently attached to a surface and being less than a hundred nanometer thick, allow the creation of functional surfaces without altering the inherent bulk properties or appearance of a product. Surface properties depend on the type and length of the polymer used, as well as on the grafting density of the polymer brush. By making use of a polymeric primer layer that is covalently linked to the substrate and creates a uniform and highly functionalized surface, polymer brush coatings with high grafting densities can be created. In this paper we report the preparation of hydrophilic as well as hydrophobic brush coatings on different substrates through the use of a poly(acrylic acid) primer layer. In addition, hydrophilic poly(ethylene glycol) brush coatings thus produced were shown to decrease adhesion of marine bacteria.