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At least 271 records · Page 15Linked to original sources
PubMed2004

An ex vivo evaluation of resin-modified glass polyalkenoates and polyacid-modified composite resins as orthodontic band cements.

OBJECTIVES: The objective of this ex vivo study was to assess the use of resin-modified glass polyalkenoates and polyacid-modified composite resins, as orthodontic band cements. MATERIALS AND METHOD: Plain stainless steel bands were cemented to 350 human extracted third molar teeth using 1 of 7 different cements. Following complete cement cure, half of each sample group was exposed to mechanical stress in a ball mill. Stressed and unstressed samples were tested in tension and the stress at which initial cement failure recorded. The mode of failure was recorded using an adhesive remnant evaluation. RESULTS: The mean band retention stresses offered by the cements studied ranged from 0.96 to 1.56 MPa. Fuji Ortho provided the highest mean band retention stress in "stressed" (1.56 MPa) and "unstressed" (1.45 MPa) states. Exposure to mechanical stress did not appear to significantly influence band retention or mode of cement failure for most cements. Fuji Ortho cement recorded the highest Weibull modulus for all cements tested. Virtually all samples failed at either the cement/enamel or cement band interface. CONCLUSIONS: Significant differences in band displacement stress values and mode of failure were demonstrated between the cements studied. However, generic comparisons were difficult to make.

Acrylic Resins↗
PubMed2006

Effect of resin liners and photoactivation methods on the shrinkage stress of a resin composite.

PURPOSE: This study was undertaken to evaluate the effect of three different photoactivation methods on the polymerization shrinkage stress of a resin composite using different resin liners. MATERIALS AND METHODS: Three photoactivation methods using a quartz-tungsten-halogen light were evaluated: continuous light, soft start, and intermittent light. Three lining groups were tested: one or three coats of adhesive, and flowable composite. The stress was measured using a universal testing machine. After the stress measurement, Knoop hardness numbers (KHNs) were evaluated to verify indirectly the degree of conversion of the composite using the three photoactivation methods. The data were submitted to analysis of variance and Tukey's test (p < .05). RESULTS: Intermittent light was always associated with statistically lower stress values when compared with continuous light. Statistical differences were not observed when continuous light and soft start were compared. The use of a flowable composite liner significantly reduced the stress generation when compared with the use of one adhesive coat. The three adhesive coats groups showed intermediate stress values. The hardness test showed no statistical difference between that achieved with continuous light and soft start. These two methods showed statistically higher KHNs when compared with results with intermittent light. CLINICAL SIGNIFICANCE: Photoactivation using intermittent light may lead to a significant reduction in shrinkage stress levels. This effect could be attributed to a significant reduction of the polymerization rate and/or a decrease in the degree of conversion. The use of a flowable composite liner reduced the stress levels when compared with levels when one coat of adhesive was used. This is possibly related to the higher thickness of the flowable composite layer.

Analysis of Variance↗
PubMed1998

Adhesion of adhesive resin to dental precious metal alloys. Part I. New precious metal alloys with base metals for resin bonding.

New dental precious metal alloys for resin bonding without alloy surface modification were developed by adding base metals (In, Zn, or Sn). Before this, binary alloys of Au, Ag, Cu, or Pd containing In, Zn, or Sn were studied for water durability and bonding strength with 4-META resin. The adhesion ability of the binary alloys was improved by adding In equivalent to 15% of Au content, Zn equivalent to 20% of Ag content, and In, Zn, or Sn equivalent to 5% of Cu content. There was no addition effect of the base metals on Pd, however 15% of In addition improved adhesion with Pd-based alloys containing equi-atomic % of Cu and Pd. The alloy surfaces were analyzed by XPS and showed that oxides such as In2O3, ZnO, or SnO play an important role in improving the adhesive ability of the alloys.

Acrylic Resins↗
PubMedDate not supplied

The effect of collagen removal and the use of a low-viscosity resin liner on marginal adaptation of resin composite restorations with margins in dentin.

This study evaluated the influence of collagen removal and the use of a low-viscosity liner on the marginal quality of composite restorations for the total-etch system, Prime & Bond 2.1 (PB) and the self-etching primer system, Clearfil SE Bond (CSEB), in high C-factor cavities with margins in dentin. High C-factor cavities were made on dentin exposed from ground labial surfaces of 100 bovine lower incisors, randomly assigned to 10 treatment groups and restored with composite Z 250, placed in bulk. In Group 1 (PB), control group, PB was applied according to the manufacturer's directions; in Group 2 (PB/PLF), an intermediate layer of low-viscosity composite Protect Liner F (PLF) was applied on the bonding resin surface; in Group 3 (PB/SH) following acid-etching, the surfaces were treated with 10% sodium hypochlorite (SH) for one minute and in Group 4 (PB/SH/PLF), the same procedure was conducted as for Group 3, plus an intermediate layer of PLF was applied as for Group 2. In Group 5 (CSEB), the control group, CSEB was applied according to the manufacturer's directions; in Group 6 (CSEB/PLF), an intermediate layer of PLF was applied; in Group 7 (SH/CSEB), the cavity surface was pre-treated with SH; in Group 8 (SH/CSEB/PLF), SH pre-treatment was conducted as for Group 7, then an intermediate layer of PLF was applied; in Group 9 (CSEB/SH), after CSEB-primer application, the surface was treated with SH, followed by CSEB-adhesive application and in Group 10 (CSEB/SH/PLF), the same was conducted as for Group 9, then an intermediate layer of PLF was applied. The specimens were stored at 37 degrees C for 24 hours, polished, molded and replicas were obtained in epoxy resin. The replicas were gold-sputter coated and observed by SEM (300x) for marginal quality classification. The Kruskal-Wallis non-parametrical multi-comparison Test (p<0.05) was used to obtain statistical analysis of the data. Results demonstrated that both adhesive systems in the control groups presented low marginal quality and a high variability. The use of an intermediate layer of PLF significantly improved the marginal quality with the CSEB system but had no effect with the PB system. Collagen depletion with SH enhanced marginal quality for the PB system and did not influence the CSEB system results.

Acetone↗
PubMed2003

Bond strengths of polyacid-modified resin composites and a resin-modified glass-ionomer cement to primary dentin.

PURPOSE: To evaluate the bond strengths of three polyacid-modified resin composites and one resin-modified glass-ionomer cement to caries-simulated primary dentin after 18-months' water immersion. METHODS: Dyract AP, Compoglass F, F2000 and Vitremer were used as test materials. Standardized preparations cavities with a C-factor of 5 were prepared in primary molars. Half of the cavities were stored in a demineralizing media for 7 days to simulate caries-affected dentin. Thereafter, all preparations were restored with the test materials, after which the specimens were stored in water for 18 months, changing the water every week. The specimens were subjected to a microtensile test and all bond strength data (in MPa) were statistically analyzed using one-way analysis of variance (ANOVA) and Tukey HSD tests at P < 0.01. RESULTS: The mean microtensile bond strength to normal primary dentin specimens were 11.2 +/- 1.5 (Dyract AP), 10.6 +/- 2.1 (Compoglass F), 10.8 +/- 1.1 (F2000) and 7.3 +/- 1.6 (Vitremer), while those to the caries-simulated dentin were 4.1 +/- 0.7 (Dyract AP), 3.0 +/- 0.6 (Compoglass F), 2.3 +/- 0.9 (F2000) and 1.9 +/- 0.5 (Vitremer). SEM evaluation of the unfractured specimens revealed evidence of gap formation in the adhesive interface in all samples.

Analysis of Variance↗
PubMed2003

Five-year double-blind randomized clinical evaluation of a resin-modified glass ionomer and a polyacid-modified resin in noncarious cervical lesions.

PURPOSE: The aim of this double-blind randomized study was to compare the clinical performance of a resin-modified glass ionomer (Vitremer, 3M) and a polyacid-modified resin (Dyract, Dentsply DeTrey) in noncarious Class V restorations after 5 years. MATERIALS AND METHODS: Twelve patients, having at least one pair of equal-sized noncarious cervical lesions under occlusion and a mean age of 40 years (range 19 to 63 years; median 41), were enrolled in this study. A total of 32 restorations (16 with each material) were placed according to the manufacturers' instructions by two calibrated operators. Two other independent examiners evaluated the restorations at baseline and after 5 years according to the USPHS criteria. The assessment criteria were: retention, anatomical form, marginal adaptation and marginal discoloration, color match, surface texture, and secondary caries. Statistical analysis was conducted using Fisher's exact test (alpha = 0.05). RESULTS: No secondary caries was detected with either material. The retention rate for Vitremer (93%) and for Dyract (78.5%) did not differ significantly (p > 0.05). Regarding anatomical form, only two restorations of each material were recorded as bravo. In terms of marginal adaptation, 38.5% of Dyract restorations were rated alpha and 61.5% bravo, while 84.6% of Vitremer restorations were rated alpha and only 15.4% bravo (p < 0.05). For marginal discoloration, 18.2% of Dyract restorations and 84.6% of Vitremer restorations were rated alpha, with the remaining rated bravo. 86% of Vitremer restorations were rated as bravo and 23% alpha for both surface texture and color match. All Dyract restorations were classified as alpha regarding surface texture, and only two Dyract restorations (18.2%) were classified as bravo in the color match item. CONCLUSION: The marginal adaptation of the RMGIC (Vitremer) was significantly better, the marginal discoloration lower, and the retention rate higher (though not significantly) than that of the PMRC (Dyract) after 5 years in situ. Dyract performed better in terms of surface texture and color match in noncarious Class V restorations after 5 years.

Adult↗
PubMed2006

One-year clinical evaluation of two resin composites, two polymerization methods, and a resin-modified glass ionomer in non-carious cervical lesions.

AIM: The aim of this study was to examine clinically relevant data on four restorative procedures for non-carious cervical lesions using United States Public Health Service (USPHS)-compatible clinical and photographic criteria and to compare different methods of analyzing clinical data. METHODS AND MATERIALS: Fourteen patients with at least one or two pairs of non-carious lesions under occlusion and a mean age of 50 were enrolled in this study. A total of 56 restorations (14 with each material) were placed by three experienced, calibrated dental practitioners. Two other experienced and calibrated practitioners, under single-blind conditions, followed up on all restorations for a period of one year. Three materials were randomly placed: a micro-hybrid composite with two polymerization methods (G1 and G2), a flowable micro-hydrid composite (G3), and a resin-modified glass ionomer (G4). Statistical analysis was performed using the Kruskall-Wallis test (p<0.05) and a Mann-Whitney U modified test with a corrected significance level. RESULTS: At the one year evaluation time, there were no restorations with secondary caries and the retention rates in G1 (IntenS with a hard polymerization), G2 (IntenS with a soft polymerization), G3 (Filtek flow), and G4 (Fuji II LC) were 85.7% (two losses), 92.8% (one loss), 100%, and 100%, respectively. The total visual comparison of the results at baseline (15 days later) showed significant differences only with the clinical acceptance criterion: G1 was different from G2, with a soft polymerization device (p<0.05). In terms of surface quality at one year, G1, G2, and G3 exhibited a statistically significant difference from G4, p<0.05. The digital analysis at baseline showed significant differences only with the clinical acceptance criterion: G1=G2 was different from G3=G4, p<0.05. At one year, only the microporosity criterion showed any statistical differences: G1=G2=G3 was different from G4, p<0.05. CONCLUSIONS: The resin-modified glass ionomer was easier to use and had a high retention rate, but it failed in terms of surface quality (visual mode) and porosity (digital mode) criteria compared to the others groups. Overall results showed no difference between groups G1 (hard-polymerized) and G2 (soft-polymerized), and only G1 was affected by the marginal edge (p<0.03) and integrity criteria (p<0.02) at one year.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1979

[Studies on the thinning of the upper acrylic resin complete denture with the reinforced palate. (Part 1). Thinning of the resin denture base with the standard shape (author's transl)].

The acrylic denture bases are most commonly used as compared with metallic denture bases at present. For this reason, it is due to many excellent properties, for example, simple processing, easy repair, cheapness and so on. But an inherent disadvantage is liability of an acrylic denture base to make thick so as to maintain stiffness and strength and it makes patients uncomfortable. Therefore, the purpose of this paper is to make the palatal region of the upper complete denture thin with about 0.7 mm in thickness, and to keep the same mechanical properties as the normal resin dentures using the composites materials with carbon cloth. Tensils test of the plate test-piece and uniform bending test of the upper complete denture with steel wings were respectively performed. The results obtained in this investigation are as follows: 1) The acrylic composites reinforced with carbon cloth have shown the superior mechanical properties to be compared with the acrylic resin to be generally used. 2) The thickness of the reinforced thin denture is decreased to 0.7 mm (its thickness is 60% of the normal thickness of the one), nevertheless, the stiffness and strength are increased with the using of the composite materials. 3) The region of highest surface tensile stress in the denture was on the polished surface of the palatal aspect of the denture in the area immediately behind the anteriors, but at this region, the strain of the reinforced thin denture base decreased its strain 10% in comparison with the non-reinforced normal thick one.

Acrylic Resins↗
PubMed1982

[Studies on dental self-curing resins (19) - adhesion of 4-META/MMA-TBB resin to pretreated dentine (author's transl)].

A new 4-META/MMA-TBB adhesive resin has been studied and the effectiveness on adhesion to tooth substrates and dental alloys was reported previously. Here we are showing affection of cleaner or etchants on the adhesion between dentines and the 4-META/MMA-TBB resin. The adhesive strength becomes superior, 18 MPa, when dentines have been cleaned with a 10% citric acid-3% ferric chloride solution. On the other hand an etchant, phosphoric acid or citric acid alone, is not so effective as the mixed solution and the strength decreases to 6 MPa. Scanning electron microscopic study on pretreated dentine with several solutions is also carried out and it is found that debris on dentine should be removed but that in tubules is not necessary to be cleaned up to get good adhesion.

Acrylic Resins↗
PubMed1982

[Studies on dental self-curing resins (20) - adhesion mechanism of 4-META/MMA-TBB resin to dentine (author's transl)].

Scanning electron microscopic studies on dentine surface cleaned with a mixture of citric acid and ferric chloride, fractured surfaces parallel to the tubules of dentine and dentine with the cured adhesive and the partially demineralized fractured surfaces, tensile fractured surface of the joint on the dentine and cured adhesive resin tags impregnated in tubules were carried out to clarify the adhesion mechanism. Infiltration of monomers into dentine is more important to get good adhesion with dentine than the interlocking at dentinal tubules due to impregnated resin. Monomers with both hydrophobic and hydrophilic groups like 4-META promote the monomer infiltration. The infiltrated and cured adhesive layer in dentine is observed at the subsurface dentine zone. This zone has excellent resistance against acid demineralization.

Acrylic Resins↗
PubMed1997

Bond strengths of resin-modified glass ionomers and polyacid-modified resin composites to dentin.

PURPOSE: To measure the shear bond strength of two resin-modified glass ionomers (Vitremer and Fuji II LC) and two polyacid-modified resin composites (Compoglass and Dyract) when applied to dry dentin, dentin supplied with water pressure from the pulp, and after thermocycling. MATERIALS AND METHODS: Ninety six extracted third molars were used. The root portion was removed just below the cemento-enamel junction and the occlusal enamel was removed from the crown segment. An artificial root portion was made in Plexiglas, cemented to the crown segment and connected to a 36 cm. height water column. The tested materials were applied to the surface of dry dentin, dentin supplied with water pressure from the pulp, and after thermocycling. Shear bond strength was measured for the bonded specimens using an Instron at a crosshead speed of 0.5 mm/minute. RESULTS: There were no significant differences in bond strengths between Fuji II LC, Compoglass, and Dyract, which were significantly greater than that of Vitremer. The bond strengths of all materials were slightly increased or not affected by the presence of water pressure from the pulp. After thermocycling, the bond strengths of Fuji II LC, Compoglass, and Dyract were not significantly affected whereas those of Vitremer were significantly decreased.

Analysis of Variance↗
PubMed2002

Resin dynamics contributes to the NMR line broadening of organic molecules grafted onto a polystyrene resin.

Despite the use of high resolution magic angle spinning NMR, the NMR linewidth of anchored molecules on the commonly used Merrifield solid phase resins remains larger than that of the corresponding molecules in solution. We investigate the different mechanisms that might be at the origin of this line broadening. Experimentally, we use the CPMG method to determine the (15)N relaxation times of a tethered tripeptide and show that the slow resin dynamics significantly contributes to the transverse relaxation.

Anisotropy↗
PubMed1983

Polyamide resin: a novel immunoadsorbent. I. Preparation of polyamide resin-antigen conjugates for use in a solid phase assay for radiolabeled antibody synthesized in vitro.

A solid phase assay for radiolabeled antibody synthesized de novo in vitro has been described (1). The solid phase consists of antigen covalently bound to bromacetyl cellulose, a useful but difficult to prepare immunoadsorbent. Herein, we describe the preparation of polyamide resin immunoadsorbent and the procedure for coupling antigen to the polymer. Data are presented that show that polyamide resin-Ag conjugates can replace bromacetyl cellulose-Ag conjugates. The usefulness of this easily prepared and inexpensive immunoadsorbent is discussed.

Animals↗
PubMed2000

Highly versatile solid phase synthesis of biofunctional 4-aryl-3,4-dihydropyrimidines using resin-bound isothiourea building blocks and multidirectional resin cleavage.

A series of pharmacologically active, functionalized 4-aryl-3,4-dihydropyrimidine-5-carboxylates (DHPMs) are prepared by a versatile novel solid phase approach. In the key step, a polymer-bound thiouronium salt is condensed with unsaturated 1-ketoesters. The resulting polymer bound 1,4-dihydropyrimidines are cleaved from the resin employing multidirectional resin cleavage strategies.

Nuclear Magnetic Resonance, Biomolecular↗
PubMed2001

In vitro bond strengths of resin modified glass ionomer cements and composite resin self-cure adhesives: introduction of an adhesive system with increased bond strength and inhibition of decalcification.

This study evaluated the shear bond strength and adhesive remnant index of 5 self-cure adhesives to comparatively evaluate a new adhesive system. Extracted human incisors were randomly divided into 7 test groups of 20 each. Incisor mesh-backed brackets were bonded to the tooth specimens in each group with their respective adhesive according to the manufacturer's instructions. The specimens were thermocycled for 2 weeks at temperatures from 5 degrees to 55 degrees C to simulate oral conditions and debonded using an Instron machine. Acceptable bond strength parameters were present with the Contacto No-Mix (composite resin containing glass ionomer 8.75 MPa) and Fuji Ortho SC with acid conditioning (6.98 MPa). Contacto No-Mix had a higher bond strength (11.2 MPa) when microetching and Megabond were employed than when these adjuncts were not employed. When FUJI Ortho SC specimens were conditioned with polyacrylic acid, they showed a higher bond strength (6.98 MPa) than when bonded to unetched teeth (5.41 MPa). In test 3, EXPT-fluoride adhesive (AF) demonstrated a higher bond strength (13.44 MPa) than both resin composite Contacto No-Mix (8.8 MPa, GAC 7.4 MPa) and FUJI Ortho SC (5.41 MPa). Expt AF (Test 3) and Concise had equal bond strengths, however, the former can potentially release fluoride from the glass ionomer. Although the Ex

Adhesiveness↗
PubMed2004

Clinical performance of a resin-modified glass-ionomer and two polyacid-modified resin composites in cervical lesions restorations: 1-year follow-up.

The aim of this study was to assess the clinical performance of a resin-modified glass-ionomer cement (Vitremer) and two polyacid-modified resin composites (F2000 and Freedom) over 1 year. Nineteen patients with at least three cervical lesions were selected, providing an initial sample size of 87 restorations (29 per material), being 78 to non-carious and nine to carious lesions. Restorations were evaluated at baseline, 6 months and 1 year after placement, using modified US Public Health Service criteria: colour match, marginal discoloration, caries, anatomical form, marginal integrity and surface texture. At baseline, restorations were considered as acceptable for all criteria. At 1-year recall, 21 restorations per material were re-examined. Freedom was rated Bravo or Charlie for all the examined criteria and Vitremer earned an Alfa rating solely for the criterion caries. On the contrary, F2000 showed the best overall results, although presenting significant alteration in colour match. Statistical analysis of data was performed using chi-square and Mc Nemar tests. As to the evaluated periods, significant difference was observed solely between baseline and 1-year recall. Freedom and Vitremer were statistically different (P < 0.01) as to anatomical form and surface texture. For F2000, significant difference (P < 0.05) was noticed as to colour match and anatomical form. After 1-year follow-up, F2000 showed the most acceptable results as to the analysed criteria.

Adult↗
PubMed2005

An investigation into the use of two polyacid-modified composite resins (compomers) and a resin-modified glass poly(alkenoate) cement used to retain orthodontic bands.

The aim of this investigation was to determine the effectiveness of a conventional glass poly(alkenoate) cement (Intact) and newer polyacid-modified composite resin cements (Transbond Plus and Ultra Band-Lok) to retain orthodontic bands. In the in vitro part of this study, stainless steel bands were cemented to 240 extracted third molar teeth in three test groups comprising Intact, Transbond Plus and Ultra Band-Lok. The force to deband (N) for all three cements was recorded using an Instron universal testing machine after the following observation periods: 20 minutes and 3, 6 and 12 months. The results indicated that all three cements increased their median force to deband after 12 months. Of the two compomers, Transbondtrade mark Plus demonstrated the highest median force to deband at all four time intervals. In the in vivo part of the study, 30 patients participated in a randomized cross-mouth clinical trial where the molar bands were cemented in place using either Intact or Transbond Plus. Ultra Band-Lok was not used in the clinical part of the study. The results showed there to be no clinically significant difference in band failure rates between the two cements. When patients were asked to score each for taste, there was a significant difference, with the glass poly(alkenoate) cement (Intact) being more acceptable than the polyacid-modified composite Transbond Plus (P < 0.001). No significant differences were observed in the in vitro median force to deband or in vivo band failure rates between the glass poly(alkenoate) cement and the polyacid-modified composite resins. The choice of cementing agent can therefore be made on patient factors, e.g. taste, or operator factors, e.g. ease of handling, cost and shelf life.

Cementation↗
PubMed1993

Disulfide linkage to polyacrylic resin for automated Fmoc peptide synthesis. Immunochemical applications of peptide resins and mercaptoamide peptides.

The use of disulfide bonds for peptide-resin linkage in solid-phase peptide synthesis was investigated using polyacrylic polymers (Expansin) and automated Fmoc methodology. The disulfide moiety was bound to the support either by coupling a protected bifunctional handle or by an original stepwise procedure. Among the three different disulfide handles that were investigated, only the aminoethyldithio-2-isobutyric acid (AEDI) handle was stable enough to achieve peptide synthesis. A series of peptides of up to 10-20 amino acids were prepared in this manner, in good yield and purity. Rapid and quantitative peptide release was obtained by reduction with equimolecular amounts of dithiothreitol at pH 9 or tris(2-carboxymethyl) phosphine at pH 4.5. This allowed direct and rapid coupling of the released cysteamide peptides to an activated protein carrier and the use of free or resin-bound forms of the antigen in immunoassays.

Acrylic Resins↗