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PubMed1991

[Bond strength of newer dentine adhesive systems].

Introduction of new dentine bonding agents in a practice of dentistry, variety of results on their crucial characteristics in foreign literature and lack of information in our literature led to a necessity to conduct own scientific research on dentine adhesives in order to facilitate the choice of available products. The purpose of this study was to estimate the adhesive strength of different dentine bonding agents to a treated human dentine immediately after light curing of a compatible composite material. Shear and tensile bond strength of Tripton, Gluma, Scotchbond-2 and Dentin Protector was measured. Control material was glass-ionomer base-cement Vitrabond. Human extracted premolars from both jaws were prepared to a flat surface from either occlusal or buccal aspect, and materials were applied, respectively. The results showed: a) values of shear bond strength ranged from 2.01-3.92 MPa with no statistical differences between tested systems; b) tensile bond strength varied from 13.7-26-84 MPa; the highest value showed Scotchbond-2, following by Gluma, but significantly lower values showed Tripton and Dentin Protector; c) the aspect of prepared tooth crown had no significant effect on bond strength with the exception of shear bond strength for Gluma-system, when applied on buccal surface showed significantly higher values than applied occlusally; d) dentine-bonding agents which dissolve smear layer with acid components and remove it from prepared dentine surface showed stronger adhesion than agents which leave this debris on a dentin surface.

Adhesiveness↗
PubMed1995

Long-term survival of fragment bonding in the treatment of fractured crowns: a multicenter clinical study.

In three Scandinavian dental facilities, a series of 334 permanent incisors with fractures of the crown or crown and root was treated by reattachment of the fragment with a resin composite. Two centers (Oslo and Stockholm) employed acid etching of enamel alone for fragment bonding (n = 146), while the third center (Copenhagen) used a combination of enamel etching and dentinal bonding (n = 188). Although the final retention rate of fragment bonding was similar in the two groups, it took the dentinal bonding group almost three times as long to drop to 50% fragment retention. This difference could be attributed to greater bonding strength in the dentinal bonding group, greater risk of second injury in the younger acid-etching group, or difficulty in maintaining a dry operative field in the younger age group. The good fragment retention, acceptable esthetics, and pulpal vitality observed in the present series indicate that reattachment of the coronal fragment is a realistic alternative to placement of conventional resin-composite restorations.

Acid Etching, Dental↗
PubMed2006

Microcapsules made of weak polyelectrolytes: templating and stimuli-responsive properties.

Hollow microcapsules composed of the weak polyelectrolytes poly(allylamine hydrochloride) (PAH) and poly(methacrylic acid) (PMA) are templated on silicon oxide particles using the layer-by-layer adsorption. The colloidal template is removed with a buffer system of hydrofluoric acid and ammonium fluoride. With this buffer system, the template can be dissolved in mild pH conditions, where the polymeric layers are still stable. The morphology and the thickness of the resulting capsules are investigated with atomic force microscopy. The resulting hollow capsules show pH-dependent properties. The shells are stable over a broad pH range and swell and immediately dissolve for pH values below 2.3 and above 11. If the molecular weight of the poly(methacrylic acid) is increased, the enhanced entanglement of the polymers results in a reversible swelling of the capsules at low and at high pH. The swelling degree is probed with confocal laser scanning microscopy. In addition to the pH-dependent size variations, the different ionization degree of poly(methacrylic acid) as a function of pH is used for the selective binding of calcium ions.

Binding Sites↗
PubMed1992

Adhesive properties of modified glass-ionomer cements.

The incorporation of water-soluble polymers and/or vinyl monomers into glass-ionomer cements can yield toughened "hybrid cement-composites". This study compared a commercial water-hardening glass-ionomer cement and seven experimental hybrids in their bonding to both dentin and Silar composite. The cements were sanded and phosphoric-acid-etched or left with an unaltered matrix-formed surface when adhesion to composite was tested. The seven hybrids included: 15% 2-hydroxyethyl methacrylate (HEMA) with appropriate initiators/activators, 29% HEMA, 27% HEMA + 0.5% polyacrylic acid (PAA), 0.5% PAA, 1.5% PAA, 2.5% polyvinyl alcohol, and 2.5% gelatin. Acceptable bond strengths to applied composite and to dentin were observed for most of the modified hybrid cements. There were higher bond strengths with composite when the hybrids were left unetched. Bonding of some unetched, HEMA-containing cements achieved bond strengths (29% HEMA, 10.09 MPa) significantly higher than those of the unmodified cement (4.92 MPa). Resin-modified cements may promote better bonding by improved interaction and compatibility with the resin component of the composite.

Acid Etching, Dental↗
PubMed2005

Formulation and characterization of a novel fluoride-releasing dental composite.

OBJECTIVES: The aims of this study were to formulate a novel fluoride-releasing dental composite and to evaluate its mechanical properties, fluoride release and recharge capabilities, water sorption and solubility. METHODS: A fluoride-releasing dimethacrylate monomer containing a ternary zirconium fluoride chelate was synthesized. Three experimental fluoride-releasing composites were fabricated with different monomer formulas (wt.%)-(1) Control A: 40 BisGMA/40 TEDMA/20 UEDMA; (2) EXPERIMENTAL: 20 F-releasing monomer/20 BisGMA/40 TEDMA/20 UEDMA; (3) Control B: the same formula as Control A except that it contained 10 wt.% (of total monomer) tetrabutylammonium fluoride (TBAF), which had a fluoride content equivalent to EXPERIMENTAL. All three materials had the same filler content: 55 wt.% silanized fluoroaluminosilicate particles (0.8 microm) and 10 wt.% silanized fumed silica (14 nm). All materials contained 0.17 wt.% camphorquinone (CQ) as a photoinitiator and 0.69 wt.% ethyl-4-dimethylaminobenzoate (4EDMAB) as an accelerator. The materials were tested for fluoride release (for 184 days), fluoride recharge, compressive and flexure strength, water sorption and solubility. The data were analyzed using ANOVA and Tukey-HSD tests, and Kruskal-Wallis test. RESULTS: The experimental composite had significantly higher fluoride release and fluoride recharge capabilities than both Control composites. It had significantly better physical and mechanical properties than Control B. SIGNIFICANCE: The combined use of the fluoride-releasing dimethacrylate monomer and fluoride-releasing filler can provide sustained high fluoride release and recharge as well as acceptable mechanical and physical properties. Simply adding organic fluoride salt in the monomer yields composites with poor mechanical and physical properties.

4-Aminobenzoic Acid↗
PubMed1991

N-(2-hydroxypropyl)methacrylamide copolymers targeted to the hepatocyte galactose-receptor: pharmacokinetics in DBA2 mice.

N-(2-Hydroxypropyl)methacrylamide (HPMA) copolymers containing doxorubicin (DOX) and galactosamine can be targeted to the hepatocyte galactose receptor for organ-specific chemotherapy of primary and metastatic liver cancer. Here we report the dose-dependent pharmacokinetics of this macromolecular conjugate. Following intravenous administration to mice most efficient liver targeting was seen at low dose (0.05 mg DOX kg-1), with receptor saturation observed using higher bolus doses. Repeated low dose bolus injections did not cause down-regulation of the galactose receptor and targeted drug delivery rates of greater than or equal to 2 micrograms DOX g-1 liver h-1 were achieved. DOX is released from such conjugates intracellularly via action of lysosomal proteinases. It was shown that isolated rat liver lysosomal enzymes (Tritosomes) can release unmodified DOX from the peptidyl side chain Gly-Phe-Leu-Gly at a rate greater than or equal to 3 micrograms DOX g-1 liver h-1 i.e. the hydrolytic capacity is greater than the observed rate of drug delivery to the liver lysosomes in vivo. Although most conjugate would be captured by normal hepatocytes following intravenous administration, it was shown that the human hepatoma cell line HepG2 retains the galactose receptor, accumulating and processing the conjugate efficiently. Potential dose limiting toxicities of such drug conjugates could include cardio- or hepatotoxicity. Administration of conjugate reduced the 15 min heart level of DOX approximately 100-fold compared with that observed for an equivalent dose of free drug. Preliminary experiments showed that plasma levels of alkaline phosphatase, alanine transaminase and asparate transaminase did not change following administration of HPMA copolymer-daunorubicin (DNR) (10 mg DNR kg-1) indicating no significant heptatoxicity.

Amino Acid Sequence↗
PubMed2005

Does hybridization of intraradicular dentin really improve fiber post retention in endodontically treated teeth?

This study tested the hypothesis that hybridization of intraradicular dentin eliminates interfacial gaps, thereby improving the coronal seal and retention of teeth restored with fiber posts. Post spaces were bonded with two types of fiber posts, using the corresponding etch-and-rinse adhesives and dual-cured resin cements. Longitudinal sections of the interfaces were examined for dentin hybridization in the coronal- and middle-thirds of the root canals. Resin replicas of these sections were evaluated for interfacial gap formation. Although intraradicular dentin hybridization was not compromised irrespective of whether the adhesives were light-cured before cementation, the universal occurrence of interfacial gaps along the hybrid layer surface or the post-cement interface reflects the challenge in bonding to post spaces with low compliance and high C-factors. The clinical success associated with bonded fiber posts is probably due predominantly to frictional retention.

Acid Etching, Dental↗
PubMed2002

In vivo influence of residual moisture on microtensile bond strengths of one-bottle adhesives.

PURPOSE: This study evaluated the microtensile bond strengths of three dentin adhesives applied on clinically moist dentin or on dentin that was dried with air for 5 seconds. The null hypothesis to test was that the level of residual moisture does not influence bond strengths when restorations are placed in vivo. MATERIALS AND METHODS: Twenty-four premolars scheduled to be extracted for orthodontic reasons from patients between the ages of 15 and 23 years were restored with one of the following adhesive systems followed by a mini hybrid composite resin: Excite (Ivoclar/Vivadent), an ethanol-based dentin adhesive; Prime & Bond NT (Dentsply/Caulk), an acetone-based dentin adhesive; and Single Bond (3M ESPE), an ethanol and water-based dentin adhesive. After extraction, the specimens were sectioned with a slow-speed diamond saw in two perpendicular directions to obtain sticks with a cross-section of 0.7 +/- 0.2 mm2. The specimens were attached to a Geraldeli device and fractured using a universal testing machine at a crosshead speed of 1 mm per minute. RESULTS: For each dentin adhesive, there were no statistical differences between means for dry dentin versus moist dentin. Single Bond and Prime & Bond NT ranked in the same statistical subset regardless of the moisture condition of the substrate. Both Excite, dry, and Excite, moist, resulted in statistically lower bond strengths than Single Bond, moist, but similar to those of Single Bond, dry, Prime & Bond NT, moist, and Prime & Bond NT, dry. CLINICAL SIGNIFICANCE: In this study, the level of residual moisture did not influence microtensile bond strengths. Clinically, the degree of moisture left on the dentin surface upon rinsing off the etching gel may not be as relevant as previously reported in laboratory studies.

Acetone↗
PubMed2002

Reversal of compromised bonding in bleached enamel.

Oxygen inhibits polymerization of resin-based materials. We hypothesized that compromised bonding to bleached enamel can be reversed with sodium ascorbate, an anti-oxidant. Sandblasted human enamel specimens were treated with distilled water (control) and 10% carbamide peroxide gel with or without further treatment with 10% sodium ascorbate. They were bonded with Single Bond (3M-ESPE) or Prime&Bond NT (Dentsply DeTrey) and restored with a composite. Specimens were prepared for microtensile bond testing and transmission electron microscopy after immersion in ammoniacal silver nitrate for nanoleakage evaluation. Bond strengths of both adhesives were reduced after bleaching but were reversed following sodium ascorbate treatment (P < 0.001). Resin-enamel interfaces in bleached enamel exhibited more extensive nanoleakage in the form of isolated silver grains and bubble-like silver deposits. Reduction of resin-enamel bond strength in bleached etched enamel is likely to be caused by a delayed release of oxygen that affects the polymerization of resin components.

Acid Etching, Dental↗
PubMed1989

Human pulp reactions to resin restorations performed with different acid-etch restorative procedures.

Fifty-eight experimental resin restorations were performed in intact, human premolars, using different leakage-reducing restorative procedures. These were conventional acid-etching and acid-etching followed by cavity treatment with an intermediary layer of low-viscous resin or the dentin adhesive NPG-GMA/ethanol. The teeth were extracted after 4 months and examined for pulpal inflammation/necrosis (I), reduction of odontoblasts (OR), and formation of tertiary dentin (TD). By the general linear model procedure, 91%, 34%, and 56% of the variations in I, OR, and TD, respectively, could be explained by variations in the experimental conditions. The significant independent variables were jaw, stage of root formation, width of pulp, width of cavity, marginal leakage, bacteria in the cavity, bacteria in the exposed dentinal tubules, and the restorative procedure. With regard to the restorative procedure the analyses showed that application of low-viscous resin increased the pulpal reactions OR and I, whereas cavity treatment with NPG-GMA/ethanol had no adverse biologic effect.

Acid Etching, Dental↗
PubMedDate not supplied

Technique sensitivity of dentin bonding: effect of application mistakes on bond strength and marginal adaptation.

This in vitro study evaluated dentin bond strength and marginal adaptation of direct resin composites according to the manufacturers' instructions and with simulated application errors. One hundred and forty cavities were prepared into disks of freshly extracted human third molars and filled with one resin composite. Dentin adhesives of the third (with self-etching primer: Syntac Classic), fourth (with total etching: Scotchbond Multi-Purpose Plus) and fifth generation (one-bottle adhesive: Prime&Bond 2.1) were used for bonding. Simulated application mistakes were as follows: 1) prolonged etching; 2) excessive drying after conditioning; 3) drying primers immediately after application and 4) drying primers excessively. After 21 days of storage and 24 hours thermocycling (1150 cycles), replicas were made and push-out testing was performed. Replicas were examined for marginal adaptation using SEM (X200 magnification). Compared with values of the control groups, application errors resulted in dramatically decreased bond strengths and reduced percentages of gap-free margins for all products tested (p < 0.05). Excessive drying after conditioning exhibited significantly less effect for the third generation adhesive than for products requiring total etching/wet bonding.

Acid Etching, Dental↗
PubMed2001

Constancy of bond strength in 5 single-bottle dentin bonding systems.

OBJECTIVE: Historically, wide variations in the shear bond strength of resin composite bonded to dentin have been reported. The purpose of this study was to compare 5 commercially available single-bottle dentin bonding systems while controlling several sources of variation in shear bond strengths. METHOD AND MATERIALS: Extracted molars were stored for 2 weeks in 0.5% Chloramine T. The teeth were mounted, the occlusal enamel was removed to expose middle dentin, and the exposed dentin was etched and treated according to 1 of 6 protocols. Finally, a cylinder of resin-based composite was bonded to the dentin. After 24 hours, specimens were fractured under shear force, and the results were recorded in megapascals. RESULTS: The type of product used was significantly associated with the mean shear bond strength observed. All products exhibited some degree of variation from specimen to specimen. One product, PQ1, exhibited less variation than the other 4 products. CONCLUSION: PQ1 was found to have a significantly higher mean shear bond strength than the other 4 products tested. There was no significant difference between specimens bonded to dry dentin and specimens bonded to wet dentin when using PQ1.

Acetone↗
PubMedDate not supplied

Effect of different application and polymerization techniques on the microleakage of proximal resin composite restorations in vitro.

This in vitro study investigated cervical microleakage of proximal resin composite restorations placed with three application and polymerization techniques. Uniform mesio-occlusal-distal (MOD) preparations featuring cervical margins above (mesial) and below (distal) the CEJ suitable for restoration with resin composite were copy milled into 33 recently extracted permanent molars. The teeth were divided randomly into three groups of 11 teeth and restored using a conventional incremental technique (Group A) and two novel curing devices (Groups B and C). After 24 hours, a dye penetration test was used to assess microleakage. Conventional placement in preparations with cervical margins in enamel had significantly lower interfacial leakage scores than those recorded for placement in preparations with margins in cementum regardless of the technique used to place the restorative material. Use of the two novel curing devices conferred no advantage in reducing microleakage irrespective of where preparation margins were placed.

Acid Etching, Dental↗
PubMed2003

In vitro evaluation of different techniques of enamel preparation for pit and fissure sealing.

PURPOSE: To compare the penetration and the imperviousness of two pit and fissure sealants according to surface treatments involving different cleaning procedures with or without subsequent acid etching. MATERIALS AND METHODS: Two sealants were used: a resin-based sealant (Concise White Sealant) and a compomer-based material (Dyract Seal) coupled with an enamel-dentin bonding agent (Dyract Seal and Prime&Bond NT). Extracted molars (n = 120) were randomly divided into 12 groups: 4 control and 8 experimental groups that received different surface treatments. Pumice, alumina, or bicarbonate was used to clean the surfaces. Phosphoric acid or non-rinse conditioner was used as acid etching agents. After sealing, the Concise White Sealant groups were directly thermocycled for 1800 cycles, while the Dyract Seal groups were stored in water for one month before thermocycling. After apex sealing and varnish coating, the fillings were stained with silver nitrate and embedded. Three to 6 cross sections of 200 microm each were made per sample to assess both sealant penetration (% of the length of the fissure) and the imperviousness of the seal (scores method). RESULTS: Concise White Sealant achieves a better enamel sealing than Dyract Seal when the teeth are treated with air abrasion or air polishing followed by etching. Acid etching is essential for good sealing, whatever the material and cleaning technique tested. Only the combination of air abrasion and phosphoric acid etching yielded a leak-free joint. CONCLUSION: This study clearly shows that penetration and sealing are two different phenomena. Ideally, an efficient sealant must have a good sealing ability and a high rate of infiltration as well, but these two properties probably do not have the same clinical relevance. The imperviousness of the seal remains the most important requirement.

Acid Etching, Dental↗
PubMedDate not supplied

Microscopic evaluation of dentin interface obtained with 10 contemporary self-etching systems: correlation with their pH.

This study investigated micromorphological differences in the hybridized complex formed using 10 commercially available self-etch bonding systems. In addition, the influence of the pH of the primer of these adhesives was evaluated. The self-etching systems tested were AdheSE, Adper Prompt L-Pop, Clearfil SE Bond, Etch&Prime 3.0 (Degussa, Germany), Prime & Bond NT Non Rinse Conditioner (Dentsply, Konstanz, Germany), One-Up Bond F, OptiBond Solo Plus Self Etch, Prompt L-Pop and Xeno III. One hundred non-carious human third molars were used. The teeth were divided into two groups of 50 and prepared for evaluation by optical microscopy or scanning electron microscopy. The specimens in each group were further divided into 10 subgroups of five specimens each to evaluate the 10 bonding systems. The pH of the primers of the bonding systems was measured. The results demonstrated morphological differences at the interface, depending on adhesive composition. The differences mainly concerned thickness of the hybrid layer, the absence or presence of microscopic voids at the adhesive-composite interface and whether the dentinal tubuli were completely sealed. The pH was not the determining factor conditioning the action of the self-etching adhesives.

Acid Etching, Dental↗
PubMed1990

Marginal bacterial leakage and pulp reactions in Class II composite resin restorations in vivo.

The presence of stainable bacteria under restorations and pulp reactions in 36 teeth restored in vivo with a modified Class II composite resin restoration with two different dentine treatment techniques were studied on three separate follow-up occasions (1-3, 7-10 and 28-32 days). Half of the cavities showed stainable bacteria at the cavity margins and bottoms. Teeth restored with method A (Gluma/Occlusin) showed significantly fewer restorations with stainable bacteria then teeth restored with method B (Life/Occlusin) (p less than 0.05). Significantly more restorations with detectable bacteria were found after 28-32 days and restorative method B (p less than 0.05). There were no differences in occurrence and grade of pulp inflammation for the different dentine treatment techniques and time periods.

Acid Etching, Dental↗
PubMedDate not supplied

Evaluation of the interface between one-bottle bonding agents and dentin by cryopreparation and low-temperature scanning electron microscopy (LTSEM). A pilot study on perfused dentinal samples.

OBJECTIVES: Dentin bonding samples are generally observed in the high vacuum chamber of an electron microscope only after completion of the bonding procedure fixation, dehydration and drying of the specimens. The purpose of this study was to observe the effect of each step in the application of various one-bottle dentin bonding agents (DBA) using cryopreparation followed by low-temperature scanning electron microscopy (LTSEM). METHODS: Prime&Bond 2.1 (P&B 2.1), Coltène Experimental (Exp.) and Syntac Single Component (Syntac SC) were applied onto perfused dentin of extracted, human third permanent molar teeth. After acid-etching, rinsing and drying, and following the application of the respective resins, the teeth were fractured at random and plunge-frozen in liquid nitrogen before examination under LTSEM. As this method preserves the state of the treated surface at the moment when it is frozen, each step of the application of the DBA can be observed as if it were a 'real-time' procedure. RESULTS: Acid-etching the dentin resulted in the removal of the smear layer for all materials tested. Those one-bottle DBAs which recommend the application of two consecutive resin layers (P&B 2.1 and Syntac SC) showed incomplete saturation of the dentinal surface after application of the first layer. With Syntac SC the incomplete saturation was more pronounced than with P&B 2.1. The use of Exp. resulted in a much more homogeneous coverage of the dentin despite only one layer of resin having been applied. CONCLUSION: It is concluded that cryo-preparation followed by LTSEM appears to be a method which allows each stage of the application of DBA to be evaluated.

Acid Etching, Dental↗
PubMed1998

Effect of a re-wetting agent on the performance of acetone-based dentin adhesives.

PURPOSE: To compare the in vitro bond strengths of two acetone-based one-bottle dentin adhesives applied to four surface moisture conditions. The tested hypothesis was that wetting a dried dentin surface with an aqueous HEMA solution would result in bond strengths similar or higher than those obtained by leaving the surface moist as per manufacturers' instructions. MATERIALS AND METHODS: Eighty flat dentin bonding sites were polished to 600-grit on middle dentin of the labial surface of bovine incisors mounted in acrylic resin. The specimens were equally and randomly divided between two acetone-based dentin adhesives (One-Step and Prime & Bond 2.1) and four different levels of surface moisture (moist dentin, dentin dried for 1 s, dentin dried for 5 s, and dentin dried for 5 s followed by re-wetting with Aqua-Prep, an aqueous HEMA solution). A composite post was then adapted to the treated area and light-cured. After thermocycling, the bond strengths were determined by testing the specimens in shear. Field Emission SEM examinations were carried out to evaluate the effects of different treatments on the dentin-resin interface. RESULTS: Statistical analysis revealed that the application of One-Step resulted in similar mean shear bond strengths for the groups in which moisture was present on the dentin surface (12.0-14.2 MPa). The mean shear bond strengths for the group in which One-Step was applied to a dried dentin surface was significantly lower (6.0 MPa). For Prime & Bond 2.1, the application of a re-wetting solution significantly increased mean shear bond strengths (13.9 MPa). The remaining three Prime & Bond 2.1 groups yielded statistically similar mean bond strengths, regardless of the surface condition (6.6-8.1 MPa).

Acetone↗