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PubMed1998

Interfacial ultrastructure of the resin-enamel region of three adhesive systems.

PURPOSE: To observe the resin/enamel interface produced by different adhesive systems. MATERIALS AND METHODS: A conventional three-step smear layer removing adhesive system (Scotchbond Multi-Purpose), a two-step smear layer removing adhesive system (Prime & Bond), and a two-step smear layer dissolving adhesive system containing a self-etching primer (Panavia 21) were evaluated. Flat enamel surfaces were obtained from approximal surfaces of 18 extracted human molars. A total of 36 surfaces were collected and divided into three groups of 12 samples. One-half of each specimen in each group was etched with 35% phosphoric acid prior to the application of each adhesive system, with the second half being kept unetched. Subsequently, resin composite was placed and polymerized for 40 seconds. The samples were fractured and immersed into HCl and NaOCl solutions, followed by critical point drying and sputter coating for examination with a field emission scanning electron microscope. RESULTS: In the etched samples, Panavia 21 and Scotchbond Multi-Purpose showed more consistent resin tag penetration than did Prime & Bond. Unetched Prime & Bond and Scotchbond Multi-Purpose samples showed minimal or no adhesive penetration in enamel surfaces.

Acid Etching, Dental↗

PubMed2004

Synthesis of AB diblock copolymers by atom-transfer radical polymerization (ATRP) and living polymerization of alpha-amino acid-N-carboxyanhydrides.

The synthesis of poly(methyl acrylate)-block-poly(gamma-benzyl-L-glutamate) (PMA-b-PBLG) diblock copolymers, using atom-transfer radical polymerization (ATRP) of methyl acrylate and living polymerization of gamma-benzyl-L-glutamate-N-carboxyanhydride (Glu-NCA) is described. Amido-amidate nickelacycle end groups were incorporated onto amino-terminated poly(methyl acrylates), and the resulting complexes were successfully used as macroinitiators for the growth of polypeptide segments. This method allows the controlled preparation of polypeptide-block-poly(methyl acrylate) diblock architectures with control over polypeptide chain length and without the formation of homopolypeptide contaminants.

Amino Acids↗

PubMed1991

Microleakage of composite resin cores treated with various dentin bonding systems.

Composite resin post and cores have gained widespread acceptance as an alternative for cast-gold post and core systems. A prefabricated metal post is generally used. Substantial microleakage at the interface between the composite resin core and the dentin substrate may occur. A tight and impervious bond between the dentin and the restorative material is critical for the longevity of core restorations. This study compared the microleakage of composite resin cores treated with various dentin bonding agents, including the recently developed Gluma, Tenure, and Scotchbond 2. The results indicated that Tenure and Scotchbond 2 bonding agents were most effective in reducing microleakage, followed by Gluma and conventional Scotchbond (Dual Cure) bonding agents. Although all proprietary dentin bonding systems used in this study significantly reduced microleakage, no system was capable of preventing microleakage completely.

Analysis of Variance↗

PubMed1991

Fracture resistance of pin-retained amalgam, composite resin, and alloy-reinforced glass ionomer core materials.

This study investigated the influence of pins on the fracture resistance of three core materials. Two or four stainless steel pins were incorporated in either amalgam, composite resin, or alloy-reinforced glass ionomer specimens. Half of the pins were surface-treated with mercury, Panavia EX resin, or hydrochloric acid before they were incorporated in the respective materials. The pins were oriented in a direction relative to the tensile stress/axis of the specimen: parallel/perpendicular (PL/PR), perpendicular/parallel (PR/PL), or perpendicular/perpendicular (PR/PR). ANOVA tested significant differences in diametral tensile strength among materials, in number of pins, in pin orientations, in surface treatments, and in other interactions. Incorporation of pins weakened amalgam the most, followed by composite resin. Pins did not weaken amalgam-reinforced glass ionomer. Pin orientation improved the fracture resistance of some specimens by two times that of the controls. Orientation of pins parallel to the tensile stress was most favorable. As the number of pins increased, the fracture resistance of amalgam significantly decreased. Acid treatment of the pin surface enhanced the bond with composite resin. Both treatments resulted in significant improvement in fracture resistance.

Analysis of Variance↗

PubMed1992

In vitro microleakage at the gingival margin of porcelain and resin veneers.

This in vitro study investigated the effect of dental surface treatments on the seal of porcelain and resin laminate veneers to tooth structure. Nine groups of 20 teeth were prepared for labial veneers--six groups with the apical margin of the veneer in dentin, two groups with the veneer wholly bordered by enamel, and one group with the apical margin coincident with the apical margin of a previously placed glass ionomer restoration. The teeth were treated with a variety of dentin-bonding agents prior to restoration of eight groups with porcelain veneers and one group with Visio-Gem microfilled resin veneers. After placement, the veneers were stored in water for 4 days, then subjected to thermocycling before silver staining and sectioning. Results showed no leakage around the margins of the veneers wholly bordered by enamel. Complete leakage was found around the glass ionomer restorations, and nearly total leakage was found along the resin-dentin interface of the resin veneers. The porcelain veneers that extended onto dentin showed variable but limited leakage for four of five of the dentin-bonding treatments.

Acid Etching, Dental↗

PubMed1995

Construction of a cDNA library for a specific region of a chromosome using a novel cDNA selection method utilizing latex particles.

A novel method is described for the rapid concentration of particular cDNAs and their mapping to specific regions of a genome. The strategy for 'cDNA scanning' is based on the hybridization of an entire library of cDNAs to a large fragment of genomic DNA that is covalently bound to latex particles. The hybridized cDNAs are eluted, amplified by PCR and cloned into a lambda vector. Selected cDNAs that hybridized to the genomic DNA are cloned, with subsequent sequence analysis. Region-specific DNA fragments prepared from a yeast artificial chromosome (YAC) clone, EG10D9, which maps to chromosome 5 of the small cruciferous plant Arabidopsis thaliana (At), were used to prepare a model system and were covalently bound to latex particles. cDNAs that hybridized to EG10D9 were concentrated by hybridization to the immobilized DNA. The hybridized cDNAs were recovered and amplified by PCR. The resultant sub-library of cDNAs of 0.5-2 kb in length was enriched about 1000-fold. The partial sequences of the cDNAs provided information about genes that are located on the EG10D9 region of the At genome. The cDNA scanning strategy provides an efficient method for the mapping of expressed genes which could be used as expressed sequence tags (EST) within a genome.

Arabidopsis↗

PubMed1993

Cytotoxicity of retrofill materials.

Dentin bonding agents reduce microleakage and enhance marginal adaption of composite resin restorations. These characteristics are advantages for their use as an endodontic retrofilling material. Because these materials will be in direct contact with vital tissues, their cytotoxic potential must be evaluated before clinical use. It was the purpose of this study to evaluate the cell cytotoxicity of amalgam, Caulk Universal Bond, Gluma, 35% HEMA, Morita Clearfil, Scotchbond 2, Super EBA, Tenure, and Tenure 5-4. VERO cells were grown in RPMI-1640 medium and cell monolayers were prepared by incubating 15 ml of the cell suspension in 60-mm culture dishes at 37 degrees C in 5% CO2. Twelve milliliters of a medium-agarose mixture containing 1% neutral red vital stain were overlayed onto the cell layer and allowed to solidify. The materials were directly exposed to the agarose overlays by inverting 6.0-mm diameter polypropylene capsules containing the cured and liquid sample materials either immediately (0 time) or after placement in phosphate-buffered saline with 1% gentamicin for 7, 15, or 30 days. Cytotoxicity was determined by measuring the zone of killed cells around the sample 24 h after placement on the agarose. Cytotoxicity was determined by measuring the zones of cell inhibition at 24 h and at 7, 15, and 30 days. Initially, all of the materials were found to be cytotoxic, except amalgam and the Tenure components. The dentin bonding primers showed a mean zone of inhibition of 13.2 mm and the cleansers a 40.0-mm zone. Amalgam demonstrated increasing cytotoxicity: 0.0 mm at 24 h to 12.0 mm at 30 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid Etching, Dental↗

PubMed1999

The influence of alloy copper content on the polymerisation of anaerobic adhesives.

OBJECTIVES: Anaerobic adhesives are capable of bonding copper-containing metal attachments to etched human enamel, where the latter surface has been rendered reactive by the use of a copper-containing surface activator. The aims of the present study were to determine whether copper attachments could also be successfully bonded to etched human enamel, using anaerobic adhesives, where no such surface activator was used. In addition, the effect of alteration in the copper content of the attachment alloy was also investigated. METHODS: Metal attachments suitable for use with anaerobic adhesives were made from one of three copper-containing alloys. Their copper contents were 8%, 19% and 99.9%. They were bonded to human enamel, which had been ground flat and etched with 37% o-phosphoric acid, using one of three anaerobic adhesives. After bench curing for one of four time periods, 10 min, 1 h, 24 h and 2 weeks, shear testing to failure was performed. The load at debond was recorded in each case. RESULTS: The results were analysed using mean force to debond (N) and 95% confidence intervals. Kaplan-Meier survival probabilities and log-rank tests were performed for the 10 min and 1 h test times. CONCLUSIONS: Each of the three anaerobic adhesives under test demonstrated a concentration effect for the copper in the metal attachments. The higher the copper content of the attachment the greater the measured force to debond and the more rapid its attainment. As determined by measured force to debond, only one adhesive. Loctite 326, underwent any significant degree of activation and, therefore, polymerisation by the lowest copper content alloy under test.

Acid Etching, Dental↗

PubMed2001

The effect of various surface treatments and bonding agents on the repaired strength of heat-treated composites.

STATEMENT OF PROBLEM: Some clinical situations may require the repair of a secondary polymerized or aged composite. The higher indirect resin conversion rate may prove to be a disadvantage if a repair procedure based on covalent bonding from unreacted methacrylate groups is attempted. PURPOSE: This study evaluated the effectiveness of different combinations of surface treatments and 2 bonding agents used to enhance heat-polymerized and aged composite repairs. MATERIAL AND METHODS: Ninety Herculite XRV and 90 Heliomolar Radiopaque specimens were prepared and then postpolymerized and stored for 4 weeks. All composites were subjected to 1 of 9 treatment regimens that involved adding fresh composite onto a corresponding postpolymerized composite (Herculite/Herculite or Heliomolar/Heliomolar). The surfaces were treated with different combinations of air abrasion, phosphoric acid, hydrofluoric acid, acetone, Special Bond II, Heliobond, and Prime & Bond 2.0. RESULTS: Surface treatment with air abrasion resulted in the strongest repairs; surface treatment with phosphoric acid resulted in the weakest repairs. CONCLUSION: The use of air abrasion and Prime & Bond 2.0 adhesive consistently improved the shear bond strength for both composites tested.

Acetone↗

PubMed2004

Tableting of Eudragit RS and propranolol hydrochloride solid dispersion: effect of particle size, compaction force, and plasticizer addition on drug release.

The application of a solid dispersion (SD) system of propranolol HCl and Eudragit RS was evaluated in the preparation of prolonged release tablets. The effects of SD size fraction, compaction force, and inclusion of plasticizers [namely diethylphtalate (DEP) and triethylcitrate (TEC)] on crushing strengths of matrices and release profile of drug were also investigated. The results showed that when compressed as a tablet, the SD system was more efficient in prolonging drug release than physical mixture. This effect was due to formation of much harder tablets of the SD system (crushing strength 8.5 kg) compared with those of physical mixtures (crushing strength 2.7 kg). All matrices of the SD system showed release rate patterns that were best described by the Higuchi equation. It was also shown that the rate of drug release decreased from 19.8% to 9.13% min(-1/2) as the SD size fraction decreased from 300-350 to 125-250 microm. However, further reduction of size fraction did not significantly affect tablet crushing strength and drug release rate. Increase in compaction force from 5 to 30 kN increased the crushing strength of matrices from 2.9 to 13.6 kg. However, the rate of drug release remained nearly unchanged beyond compaction pressure of 10 kN, indicating that crushing strength of matrices in the range of 8.5-13.6 kg did not affect drug release rate. The addition of 5% or 10% of either plasticizer (DEP or TEC) led to an increase in crushing strength of matrices and more retardation of drug release. This effect was more pronounced for higher concentrations of plasticizers. This effect was probably due to more plastic deformation of matrices under the compaction force, which helped matrices to retain their shape throughout the dissolution test.

Antihypertensive Agents↗

PubMed1991

Enamel-dentin crown fractures bonded with various bonding agents.

A method is described, by which the fracture strength of bonded, previously fractured incisors can be measured. The study employed incisors from sheep, which could be obtained in suitable numbers and with limited variation in size. The incisors were fractured parallel to the incisal edge. The mean fracture area +/- SD of central incisors was 8.45 +/- 0.89 mm2 and of lateral incisors 6.50 +/- 0.64 mm2. The enamel area constituted about 30% of the total fracture area. Acid etching of the enamel and bonding of the fractures with an unfilled resin yielded a fracture strength, which was approximately 38% of the fracture strength of fractured teeth restored with acid etching of enamel, Gluma treatment of dentin and bonding with the unfilled resin. Teeth restored in this way, but using the dentin bonding agent Tenure or Scotchbond2 instead of Gluma, exhibited mean fracture strengths which were not significantly different from that obtained when Gluma was employed as the bonding agent. The mean fracture strength by using one of the three bonding agents in combination with acid etching of enamel was about 8 MPa, which is approximately 50% of the fracture strength of intact teeth.

Acid Etching, Dental↗

PubMedDate not supplied

Microleakage of seven dentin bonding agents.

The purpose of this study was to evaluate the ability of seven dentin bonding agents to reduce dye penetration at the margins of microfill composite restorations in dentinal cavities. Forty extracted molars were selected and cleaned. Cavity preparations were made in dentin with #55 carbide burs. The preparations were restored with Silux after application of one of the following dentin bonding agents: Gluma, Scotchbond 2, Tenure, Prisma Universal Bond 2, Mirage-Bond, XR Bond, and All-Bond. Samples were thermocycled for 200 cycles between 3 degrees C and 60 degrees C, then immersed in a 0.05 percent crystal violet solution for 2 hours. The samples were embedded in clear casting resin, sectioned, and examined with a light microscope. Our results indicated that the dentin bonding systems reduced, but failed to totally eliminate, microleakage around the composite resin restorations.

Adhesives↗

PubMed2003

Reduction of polymerization shrinkage stress and marginal microleakage using soft-start polymerization.

PURPOSE: This study evaluated the influence of a soft-start light-curing exposure on polymerization shrinkage stress and marginal integrity of adhesive restorations. MATERIALS AND METHODS: Six resin-based composites (Pertac II, Tetric Ceram, Definite, Surefil, Solitaire, and Visio-Molar) were adhesively bonded to a cylindrical cavity (n = 9 per material/light) in a photoelastic material. Visible light-curing was applied using either the standard polymerization mode (800 mW/cm2 exposure duration 40 s) of the curing light (Elipar TriLight, 3M ESPE) or the exponential mode from the same device (ramp-curing: 150 mW/cm2 to 800 mW/cm2 within the first 15 s of a total curing time of 40 s). Polymerization stress was calculated at 5 minutes, 1 hour, and 24 hours postexposure from the second-order isochromatic curves obtained from photoelastic images (Matrox-Inspector). Two standardized Class V preparations were made each on the facial and lingual surfaces of 80 extracted human molars and premolars. Resin restorative systems (Pertac II/EBS Multi, Tetric Ceram/Syntac, Definite/Etch&Prime 3.0, and Surefil/Prime & Bond 2.1) were exposed using both light exposure modes (n = 20). Marginal dye penetration (2% methylene blue) was investigated separately for enamel and cementum margins after thermocycling. To obtain information on equivalent depth of cure, relative surface hardness measurements were performed on resin samples of the same material at the top surface and at 1.5 mm and 3.0 mm thickness (Zwick 3212, 10 N). RESULTS: A significant (p < .01) reduction in polymerization stress of 7.1% for Pertac II, 4.1% for Tetric Ceram, 3.6% for Definite, 3.7% for Surefil, and 6.2% for Solitaire was observed when using the exponential mode as opposed to the standard. A significant (p = .04) reduction of marginal dye penetration was found only for Pertac II/EBS Multi at the cementum margins when the soft-start polymerization was used. For the sample thickness of 3 mm, a significant higher relative bottom to top surface ratio in favor of the standard exposure mode was found (p = .001). CLINICAL SIGNIFICANCE: Depending on the restorative material, soft-start polymerization may lead to a significant reduction in marginal microleakage of adhesive Class V restorations. This effect might be attributable to a significantly lower polymerization stress, as seen from photoelastic analysis, and/or a decrease in the degree of conversion, as deducted from surface hardness ratios. However, the effect of soft-start curing mode depends on the material itself, with the most effective response from hybrid resin-based composites.

Acetone↗

PubMed2005

Inhibition of root caries progression by an antibacterial adhesive.

A dentin primer containing the antibacterial monomer 12-methacryloyloxydodecylpyridinium bromide (MDPB) has been shown to penetrate and kill the bacteria in artificially demineralized dentin. We hypothesized that an experimental adhesive system, which incorporates the MDPB-containing primer, would be effective in inhibiting the progression of root caries in vitro. Artificial caries lesions were prepared by either an acid-gel or a Streptococcus mutans culture technique on the roots of extracted human teeth. The progression of these lesions after the application of the experimental or proprietary adhesive system was examined. Further demineralization was completely prevented by the experimental adhesive system, while lesions managed with the proprietary materials showed limited ability to inhibit further demineralization. We conclude that the experimental adhesive system can inhibit the progression of root-surface caries in vitro, through a combination of its antimicrobial activity and sealing of the demineralized dentin.

Acetone↗

PubMed1990

Effect of dentin adhesives on contraction of restorative resins in cavities surrounded by acid-etched enamel.

Enamel-surrounded cavities prepared in extracted human teeth were treated with an enamel-bonding agent, one of two commercial dentin adhesives (Scotchbond 2 and Tenure), or one of two recent modifications of the Gluma system. In all cases the enamel margins were subjected to some form of acid etching. The cavities were filled with one of two different light-cured posterior resins, and the wall-to-wall polymerization contraction was assessed in the enamel surface level and, after grinding, measured and presented as linear shrinkage in the dentin surface level. The linear shrinkage varied from 0.66% in the control group, in which only composite resin was applied, to 0.28% in a group in which the cavities were pretreated with dentin adhesive. No difference could be demonstrated between the dentin adhesives or between the dentin adhesives and the enamel-bonding agent.

Acid Etching, Dental↗

PubMed2000

Effect of stepped vs. continuous light curing exposure on bond strengths to dentin.

PURPOSE: To compare the 10-min and 24-hr shear bond strengths of three dentin bonding systems, polymerized with either a standard (Optilux 401) light for 60 s, or a stepped curing light (Elipar Highlight) that delivered a low light intensity for 10 s followed by high intensity for 50 s. MATERIALS AND METHODS: Three bonding systems were used to bond two resin-based composites (RBC) to dentin at 34 degrees +/- 2C using the two curing lights. Single Bond (SB) and Prime & Bond 2.1 (P&B) were used with Z100 RBC, and EBS bonding system was used with Pertac II RBC. Ten specimens from each combination were debonded at 37 degrees +/- 1C 10 min after starting to light cure the bonding system. Ten other specimens were stored in water at 37 degrees +/- 1C for 24 hrs before debonding at 37 degrees +/- 1C (total 120 teeth). RESULTS: The 10-min mean shear bond strengths were: Standard Cure; EBS 11.9 +/- 2.9 MPa, SB 14.6 +/- 2.2 MPa, P&B 14.7 +/- 4.2 MPa: Stepped Curing; EBS 7.4 +/- 2.1 MPa, SB 13.0 +/- 3.6 MPa, P&B 15.6 +/- 4.8 MPa. The 24-hr mean shear bond strengths were: Standard Cure; EBS 14.8 +/- 5.1 MPa, SB 25.1 +/- 3.3 MPa, P&B 25.2 +/- 8.8 MPa: Stepped Curing; EBS 15.1 +/- 4.6 MPa, SB 21.9 +/- 5.9 MPa, P&B 17.3 +/- 9.2 MPa. Three way ANOVA showed significant main effects for light, bonding system and time and no 2- or 3-way interaction effects at P = 0.01. The Least-Squares Means test with Sidak's adjustment for Multiple Comparisons showed that the bond strengths obtained using the standard light were significantly greater than the bond strengths obtained using the stepped curing light (P < 0.01). The 24-hr bond strengths were significantly greater (P < 0.01) than the 10-min bond strengths. The bond strengths obtained with EBS were significantly less than SB and P&B (P < 0.01), but there were no significant differences between SB and PB (P = 0.9752).

Adhesiveness↗

PubMedDate not supplied

Adhesion of resin composite core materials to dentin.

PURPOSE: This study determined (1) the effect of polymerization mode of resin composite core materials and dental adhesives on the bond strength to dentin, and (2) if dental adhesives perform as well to dentin etched with phosphoric acid as to dentin etched with self-etching primer. MATERIALS AND METHODS: Human third molars were sectioned 2 mm from the highest pulp horn and polished. Three core materials (Fluorocore [dual cured], Core Paste [self-cured], and Clearfil Photo Core [light cured]) and two adhesives (Prime & Bond NT Dual Cure and Clearfil SE Bond [light cured]) were bonded to dentin using two dentin etching conditions. After storage, specimens were debonded in microtension and bond strengths were calculated. Scanning electron micrographs of representative bonding interfaces were analyzed. RESULTS: Analysis showed differences among core materials, adhesives, and etching conditions. Among core materials, dual-cured Fluorocore had the highest bond strengths. There were incompatibilities between self-cured Core Paste and Prime & Bond NT in both etched (0 MPa) and nonetched (3.0 MPa) dentin. Among adhesives, in most cases Clearfil SE Bond had higher bond strengths than Prime & Bond NT and bond strengths were higher to self-etched than to phosphoric acid-etched dentin. Scanning electron micrographs did not show a relationship between resin tags and bond strengths. CONCLUSION: There were incompatibilities between a self-cured core material and a dual-cured adhesive. All other combinations of core materials and adhesives produced strong in vitro bond strengths both in the self-etched and phosphoric acid-etched conditions.

Acid Etching, Dental↗

PubMedDate not supplied

Bonding to dentin: evaluation of three adhesive materials.

Dye penetration was observed in all specimens. SEM demonstrated isolated areas with no gap formation, suggesting a partial bond with dentin. A correlation is evident from the results of both techniques. Since dye-penetration was found to be similar in all the specimens, it was difficult to assess the effect of thermocycling on the amount of dye penetration. The use of posterior composites should be considered as a short-term tested procedure. It should be utilized carefully, following the manufacturer's instructions, and monitored routinely. Undoubtedly, the utilization of posterior composite materials is a very technique-sensitive procedure. Comparing the results of this in vitro study with those previously reported suggests that little improvement has been made in the bonding of the materials tested. Development of new materials and improved techniques are necessary.

Adhesives↗