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PubMed2004

The effect of thermocycling and dentine pre-treatment on the durability of the bond between composite resin and dentine.

The high bond strength between restorative resin and dentine plays an important role in long-term performance of restorations in the oral environment. A variety of treatment techniques have been described to enhance the bond strength of composite resin to dentine. Unfortunately, few studies have reported available bond durability of adhesive resins to dentine. The purpose of this research was to study the shear bond strength of composite resin to dentine pre-treated with phosphoric acid, self-etching agent or Nd:YAP laser irradiation. The durability of bond strength between resin and dentine stored in the artificial saliva thermocycling between 5 and 55 degrees C was also evaluated. The scanning electron microscope was used to assess the treated-dentine surfaces. The mean value of the shear bond strength in the acid-etching group (18.2 +/- 4.9 MPa) was the highest among the three dentine treatments (self-etching system: 12.6 +/-3.0 MPa, Nd:YAP laser: 13.4 +/- 3.3 MPa) prior to thermocycling. After thermocycling, shear strength values of all treated dentines decreased with increasing number of the cycles. When subjected to 3000 thermocycles, the mean bond strengths of these pre-treated samples to composite resin became 9.1 +/- 1.4, 7.8 +/- 1.8, and 8.1 +/- 1.7 MPa for acid-etching, self-etching and laser-irradiation, respectively, with a significant reduction of 38-50%.

Acid Etching, Dental↗
PubMed2000

Influence of additional acid etch treatment on resin cement dentin infiltration.

PURPOSE: The purpose of this study was to compare the penetration of a resin cement into dentin surfaces pretreated with self-etching primer with or without conventional acid etch. MATERIALS AND METHODS: Dentin surfaces of 8 unerupted human third molars were treated with self-etch primer (Panavia 21; Kuraray Co, Ltd, Osaka, Japan) with or without conventional acid etch treatment. A resin cement (Panavia 21) was applied according to manufacturer's instructions. Dentin/resin cement interface sections from each tooth were examined with light microscopy and scanning electron microscopy. In the light microscopy sections, exposed protein at the dentin/cement interface was stained a distinct red with Goldner's trichrome. RESULTS: The resin cement did not penetrate the depth of the zone of demineralized dentin when the self-etch primer was used in combination with conventional acid etch treatment. Inadequate resin cement penetration leaves a substantial area of exposed protein at the dentin/cement interface. In contrast, there was complete resin cement diffusion throughout the demineralized dentin when the self-etch primer was used without acid etching. CONCLUSIONS: Combining conventional acid etch treatment with a self-etching primer/resin cement system resulted in incomplete resin cement penetration and exposed protein at the dentin/cement interface.

Acid Etching, Dental↗
PubMed1985

SEM study of surface characteristics and marginal adaptation of anterior resin restorations after 3-4 years.

SEM replica technique was used to study surface characteristics and marginal adaptation of 278 anterior resin fillings 3-4 yr old. The fillings showed degradation of surfaces and margins with eroded areas and exposed macro- and microfiller particles. Cohesive failures were seen as chip fractures and marginal fractures parallel to the cavity margins. Microfiller resin fillings showed less rough surface characteristics than the conventional and hybrid composite resins in spite of a higher frequency of fillings with surface degradation. The microfiller resin fillings activated by visible light, in particular, showed relatively smooth surface characteristics with less surface degradation and less porosity. About 50% of the conventional and hybrid composite fillings showed marginal defects. The two chemically cured microfiller resin fillings showed marginal defects in 66% or 88%, whereas for the visible light cured microfiller resin fillings defects were observed in 44%.

Composite Resins↗
PubMedDate not supplied

Shear bond strength of Dicor using resin adhesive systems and light activated cement.

A laboratory study was conducted to determine the shear bond strength to dentin of etched and silane-treated Dicor castable ceramic glass using a resin cement and newer generation adhesive systems. Scanning electron microscopy (SEM) examinations were also completed to evaluate the failure sites. The mean shear bond strength of the control (resin cement only, no adhesive system) was 2.1 +/- 1.2 MPa. The shear bond strength values determined for the adhesive systems and resin cement are as follows: Prisma Universal Bond 2, 18.7 +/- 2.9; XR Primer/XR Bond, 16.9 +/- 6.4; Scotchbond 2, 15.8 +/- 6.2; Tenure Solution, 15.4 +/- 4.5; and Gluma, 14.8 +/- 5.5 MPa. SEM examinations of the debonded specimens attached with Prisma Universal Bond 2 and Tenure Solution showed a complex failure pattern with cohesive failure in the glass ceramic material and adhesive failure between the resin cement and the etched and silane-treated glass surface. The debonding pattern of specimens attached with XR Primer/XR Bond, Scotchbond 2 and Gluma were primarily adhesive between the dentin and resin materials. The results of this study support the use of an adhesive system in conjunction with a resin cement for placement of Dicor castable ceramic restorations.

Ceramics↗
PubMed2002

A novel filling technique for packable composite resin in Class II restorations.

UNLABELLED: The use of composite resin restorations in posterior teeth has increased considerably in the past few years. Specific composite resins for posterior teeth, as well as new operative techniques, have been developed to overcome some clinical difficulties. The present article describes a new technique to reconstitute the interproximal contour and contact of Class II restorations using a packable composite resin. Two lower first molars from the same patient are reported in detail, illustrating the technique step by step. The technique indicates the use of a metallic matrix band and wood wedges to provide an interproximal contour and contact with the adjacent tooth as well as to provide an adequate cervical adaptation. The first increment of the packable composite resin is applied on the gingival wall of the proximal box, packed cervically near the axial wall and, automatically, the resin climbs up in contact with the inner surface of the matrix band. This increment is sculpted and light-cured and the metallic matrix band is removed. Thus, the Class II cavities are transformed into Class I, with free access for light-curing. Small incremental layers of composite fill the remaining cavities. This technique is faster than conventional techniques and permits appropriate embrasure, better contour, and contact points. CLINICAL SIGNIFICANCE: Packable composite resins present primarily new handling characteristics that permit the development of novel filling techniques. The technique proposed in this article allows easier Class II buildup, with proper proximal contact and proximal smooth surfaces, once there are no irregularities among the composite increments. Another advantage is that there is adequate light exposure for polymerization, because the metal matrix can be removed during the restorative procedure.

Bicuspid↗
PubMed2006

In vitro antiseptic properties of an ammonium compound combined with denture base acrylic resin.

BACKGROUND: Denture base acrylic resin is easily colonised by oral endogenous bacteria and Candida spp., and eventually by extra-oral species such as Staphylococcus spp., Pseudomonadaceae or members of Enterobacteriaceae. This microbial reservoir can be responsive for denture related stomatitis and aspiration pneumonia, a life-threatening infection especially in geriatric patients. However, the oral and denture hygiene of dependent elderly individuals is extremely poor. OBJECTIVE: This in vitro study aimed to determine the per cent of a quaternary ammonium compound heat-polymerised in acrylic resin necessary to obtain denture base displaying antiseptic properties. DESIGN: Acrylic resin discs containing 2-50% ammonium polymer (Poly 202063A; 0% control) were soaked in artificial saliva for 4 weeks. Resin discs were incubated for 24 hours with Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa [37 degrees C, brain-heart infusion (BHI) broth and phosphate-buffered saline (PBS) buffer] and Candida albicans (30 degrees C, Schaedler broth), in 15 ml (168 discs) and 600 microl (168 discs) of inoculum. Microbial growth was verified at t 0 hours and t 24 hours. Data were recorded as the mean of three colony forming unit (CFU) numerations. The borderline of antimicrobial effect was determined at 0.1% viable cells. RESULTS: In 600 microl of PBS inoculum, resin specimens had a bactericidal effect (E. coli and S. aureus: 2%; P. aeruginosa: 10%) and a fungicidal effect (C. albicans: 50%). Long-term stability and toxicity in vivo studies are now required. CONCLUSION: A 2% quaternary ammonium compound polymerised with a denture acrylic resin displayed antiseptic properties after a 4-week soaking period in artificial saliva. Such antiseptic denture base could help geriatric patients to improve their oral health.

Acrylic Resins↗
PubMed1989

Colour changes on curing light-activated anterior restorative resins.

With many composite resins operators may notice a change in colour after light curing the restoration. Three types of specimen--a disc, a simulated Class III and a veneer--were made using a series of composite resins. Generally, resins became lighter or more translucent on irradiation. This was not only true for a range of resins from a single company but also the extent of the change was brand dependent. For most resins the opacity decreased with curing and most of this change occurred with a 20 seconds cure. The reflectance was approximately 50 per cent greater for resins placed over a white background than on a dark background for the thin disc specimens.

Color↗
PubMed1997

Inhibitive effect of a resin-modified glass ionomer cement on remote enamel artificial caries.

Glass ionomer cements (GICs) demonstrate the inhibition of caries lesions formed immediately adjacent to the restoration. This in vitro study was conducted to evaluate the distance at which a resin-modified GIC is able to exert its cariostatic effect on artificial enamel lesions ('remote effect'). Resin-modified GIC or bis-GMA resin was applied on the cervical third of the labial surface of 10 paired halves of bovine incisors. Specimens were separately immersed for 3 weeks in lactic acid gel which was changed every other day to reduce fluoride accumulation. Artificial lesions were examined by the cross-sectional microhardness (MHN) method. Volume percent mineral, mineral loss (delta Z value) and change in mineral content (delta M) were computed for each MHN profile, performed at distances of 0.2, 0.5, 1.0, 2.0, 4.0 and 7.0 mm from the edge of the materials. delta Z values of the resin-modified GIC group were significantly lower than those of the bis-GMA control group at all remote sites (t test, p < 0.05). The delta M caused by resin-modified GIC was more pronounced within 1.0 mm from the material which suggested that the demineralization inhibition can be divided into the near effect (< 1.0 mm). In this in vitro study, resin-modified GIC provided caries resistance in bovine enamel located at a considerable distance from the margin of the material.

Animals↗
PubMed1982

The use of an intermediate resin in the acid-etch procedure: retentive strength, microleakage, and failure mode analysis.

Three composite resin systems, one conventional (Concise) and two microfilled (IsoPast and Silar), used with and without an intermediate resin (Concise Enamel Bond), were evaluated with and without thermal stress for in vitro retentive strength and sealing ability to acid-etched human enamel. All three materials yielded significantly different shear strength values. The use of an intermediate resin significantly improved both the shear strength and resistance to microleakage of Silar, while no differences were observed for Concise and IsoPast. The thermocycling procedure did not generally or consistently affect the results. The failure mode of the three acid-etched composite resins was studied by evaluation of the failure surface and by describing the percentage of enamel, composite, and interface which were present. The use of an intermediate resin did not significantly influence the failure mode, and the correlation between the failure mode and retentive strength, although significant was low. The study confirmed the importance of adequate wetting action of a resin on the etched enamel to ensure proper bonding.

Acid Etching, Dental↗
PubMed1989

Effect of etching glass-ionomer cements on bond strength to composite resin.

The use of glass-ionomer cement in restorative dentistry has seen a revival because of its capacity for being etched and bonded to composite resin. Past investigators compared an etched cement surface with an unetched surface that was set against a smooth surface. Clinically, however, a glassy smooth surface is not produced when the cement is used as a base. Using Scotchbond bonding resin, we developed this two-part study to evaluate the tensile bond strengths of P-30TM composite resin to several glass-ionomer cements that were (a) unetched but allowed to set in air and (b) etched for 30 s with orthophosphoric acid, and to compare them with the cohesive strength of the respective cement. Using a silver nitrate staining technique, we also evaluated the microleakage of class V cavities restored with SiluxTM composite resin under a base of etched or unetched Ketac Bond cement. Although there were significant differences among three cements between their cohesive strength and the resin bond strength after the two surface treatments (p less than 0.01), the bond to the unetched surface was generally similar to that of the etched surface of the cement. The remaining groups showed no statistical difference. The microleakage was similar in the two groups. SEM micrographs showed a rough topography of the unetched cement that resembled that of the etched surface. This in vitro study suggests that acid-etching a glass-ionomer base for resin-bonding may not be necessary for specific materials. Further clinical evaluation is recommended to validate this observation intra-orally.

Acid Etching, Dental↗
PubMed1991

Influence of the solubility parameter of intermediary resin on the effectiveness of the gluma bonding system.

The aim of the present study was to investigate the effect of the solubility parameter of the intermediary resin in the Gluma system on the bonding to dentin. The solubility parameter of the resins was varied between 18.8 x 10(3) and 21.1 x 10(3) J(1/2)/m3/2 by varying the composition of the resin. The efficacy of the bonding system was determined by measurements of marginal gaps formed by polymerization contraction of a restorative resin in dentin cavities treated with the bonding system. The bonding system had maximum efficacy at a solubility parameter of the intermediary resin of delta = 20.0 x 10(3) J(1/2)/m3/2. This finding corroborates a concept of bonding to dentin that involves a mechanical interlocking by interpenetrating resins.

Analysis of Variance↗
PubMed1992

The effect of carbamide-peroxide gel on the shear bond strength of a microfil resin to bovine enamel.

Cylinders of a visible-light-cured microfil resin were formed on, and bonded to, the flattened labial enamel surfaces of young bovine incisor teeth which had previously been subjected to four different treatments: (1) immersion in 10% carbamide-peroxide gel, pH 4.7, for three h; (2) immersion in 10% carbamide-peroxide gel, pH 4.7, for six h; (3) immersion in 10% carbamide-peroxide gel, pH 7.2, for three h; and (4) immersion in 10% carbamide-peroxide gel, pH 7.2, for six h. For each experimental group, a control group of resin-bonded to saline-immersed teeth was prepared. In addition, two groups, prepared according to treatment 4, were leached in distilled water for one and seven d, respectively, prior to resin application. Specimens were stored in distilled water at 37 degrees C for seven d prior to shear-bond-strength testing. A total of 90 teeth was tested. Statistical analysis of the results indicated that there was a highly significant reduction in the shear bond strength to carbamide-peroxide-treated enamel as compared with that to saline-treated enamel. The effects of duration of peroxide treatment and pH, as well as the interaction term, were not statistically significant. Leaching of the peroxide-treated enamel in water for either one or seven d prior to resin application restored the adhesiveness of the enamel. Scanning electron microscopic examination of randomly selected, fractured test specimens indicated that the peroxide-induced reduction in enamel adhesiveness was related to alterations in both attachment-surface area at the resin-enamel interface and resin quality.

Analysis of Variance↗
PubMed1995

Tensile strength of thin resin composite layers as a function of layer thickness.

As a rule, cast restorations do not allow for free curing contraction of the resin composite luting cement. In a rigid situation, the resulting contraction stress is inversely proportional to the resin layer thickness. Adhesive technology has demonstrated, however, that thin joints may be considerably stronger than thicker ones. To investigate the effects of layer thickness and contraction stress on the tensile strength of resin composite joints, we cured cylindrical samples of a chemically initiated resin composite (Clearfil F2) in restrained conditions and subsequently loaded them in tension. The samples had a diameter of 5.35 mm and thicknesses of 50, 100, 200, 300, 400, 500, 600, and 700 microns, 1.4 mm, or 2.7 mm. None of the samples fractured due to contraction stress prior to tensile loading. Tensile strength decreased gradually from 62 +/- 2 MPa for the 50-microns layer to 31 +/- 4 MPa for the 2.7-mm layer. The failures were exclusively cohesive in resin for layers between 50 and 400 microns thick. Between 500 and 700 microns, the failures were cohesive or mixed adhesive/cohesive, while the 1.4- and 2.7-mm layers always failed in a mixed adhesive/cohesive mode. For the resin composite tested, the contraction stress did not endanger the cohesive strength. It was concluded that if adhesion to tooth structure were improved, thinner adhesive joints might enhance the clinical success of luted restorations.

Composite Resins↗
PubMed1998

Distortion behavior of heat-activated acrylic denture-base resin in conventional and long, low-temperature processing methods.

There have been many reports on fatal distortion of heat-activated acrylic denture-base resin which is still widely used in the field of removable prosthodontics. However, these reports have failed to report quantitatively on polymerization and thermal shrinkage factors. In the present study, we attempted to verify that the shrinkage of heat-activated acrylic denture-base resin was caused mainly by thermal contraction after processing. Furthermore, we examined the degree of distortion resulting from long, low-temperature processing, and compared the results with that of the conventional method. The strain gauge and thermo-couple were embedded in a specimen at the time of resin packing. The measurement started from the beginning of processing and continued until the specimen was bench-cooled and immediately before and after it was de-flasked, as well as during seven-day immersion in water at 37 degrees C. The resin expanded when processed by the conventional method. Meanwhile, mild shrinkage, possibly polymerization shrinkage, was observed when the resin was processed by the low-temperature method. This suggested that polymerization shrinkage was compensated for by thermal expansion during processing by the conventional method. Moreover, the shrinkage strains in the period from the completion of processing to immediately after de-flasking, in both the conventional and low-temperature methods, were identical to the theoretical value of thermal shrinkage which we obtained by multiplying the linear coefficients of thermal expansion by temperature differences. The shrinkage strain in the specimen processed by the low-temperature method, measured from the end of processing to immediately after de-flasking, averaged 64% of that in the specimen processed by the conventional method. The results revealed quantitatively that the shrinkage of heat-activated acrylic denture-base resin was mainly thermal shrinkage, and demonstrated the advantage of the low-temperature method in reducing thermal shrinkage.

Acrylic Resins↗
PubMed1990

Effect of resin use in the post-embedding procedure on immunoelectron microscopy of membranous antigens, with special reference to sensitivity.

To investigate quantitatively the effect of resins on the sensitivity of immunoelectron microscopy of membranous antigen, ultra-thin sections of bovine epithelial tissue embedded in five different kinds of resins [JB-4 (JB4), LR Gold (LRG), Lowicryl K4M (K4M), Quetol 812 (Q812), and Spurr's (Spurr) resin] were labeled specifically with anti-desmosomal glycoprotein I(DGI) antibody followed by protein A-gold (PAG) conjugates. When we compared the labeling intensity expressed as the number of PAG particles per 500-nm length of the desmosomal region along the membrane, three hydrophilic resins (JB4, LRG, and K4M) showed much greater levels of labeling intensity than did epoxy resins (Q812 and Spurr), which had a negative value. The three hydrophilic resins showed only minor differences in their levels of labeling intensity. The intensity obtained with JB4, which was the highest of the three, was further increased by pretreatment of the ultra-thin sections with methyl methacrylate monomer (MM) for 5 min. On the basis of these results, wide applicability of this new technique for membranous antigens, which have been difficult to detect positively by any previously employed techniques, is suggested.

Animals↗
PubMed2004

Effects of dragon's blood resin and its component loureirin B on tetrodotoxin-sensitive voltage-gated sodium currents in rat dorsal root ganglion neurons.

Using whole-cell patch clamp technique on the membrane of freshly isolated dorsal root ganglion (DRG) neurons, the effects of dragon's blood resin and its important component loureirin B on tetrodotoxin-sensitive (TTX-S) voltage-gated sodium currents were observed. The results show that both blood resin and loureirin B could suppress TTX-S voltage-gated sodium currents in a dose-dependent way. The peak current amplitudes and the steady-state activation and inactivation curves are also made to shift by 0.05% blood resin and 0.2 mmol/L loureirin B. These results demonstrate that the effects of blood resin on TTX-S sodium current may contribute to loureirin B in blood resin. Perhaps the analgesic effect of blood resin is caused partly by loureirin B directly interfering with the nociceptive transmission of primary sensory neurons.

Animals↗
PubMed2005

Forensic analysis of architectural finishes using fourier transform infrared and Raman spectroscopy, part I: the resin bases.

The ability of Raman spectroscopy and Fourier transform infrared (FT-IR) microscopy to discriminate between resins used for the manufacture of architectural finishes was examined in a study of 39 samples taken from a commercial resin library. Both Raman and FT-IR were able to discriminate between different types of resin and both split the samples into several groups (six for FT-IR, six for Raman), each of which gave similar, but not identical, spectra. In addition, three resins gave unique Raman spectra (four in FT-IR). However, approximately half the library comprised samples that were sufficiently similar that they fell into a single large group, whether classified using FT-IR or Raman, although the remaining samples fell into much smaller groups. Further sub-division of the FT-IR groups was not possible because the experimental uncertainty was of similar magnitude to the within-group variation. In contrast, Raman spectroscopy was able to further discriminate between resins that fell within the same groups because the differences in the relative band intensities of the resins, although small, were larger than the experimental uncertainty.

Architecture↗
PubMed1981

Surface mechanical properties of stone, resin, and metal dies.

Two improved stone die materials (Duroc and Silky Rock) used with water and with a hardener, one resin die material with dispersed metal powder (Die-Met), and copper and silver electroplated metal die materials were evaluated for surface mechanical properties. The improved stone dies had the highest surface roughness, intermediate surface hardness and the highest loss of material in two-body abrasion. The use of a hardener decreased the surface roughness, but did not improve abrasion resistance. The improved stone dies, with or without hardener, showed brittle failure in single-pass sliding at low normal loads. The resin dies had the lowest hardness. The unfilled resin die had low surface roughness and was similar to metal dies. The resin-metal die had a surface roughness similar to the improved stone dies. The presence of dispersed metal powder in the resin did not increase the hardness. Both resin die materials had intermediate values of material loss in two-body abrasion and showing tensile cracking and loss had intermediate values of material loss in two-body abrasion and showed tensile cracking and loss of material on single-pass sliding at medium normal loads. The metal dies had the highest hardness and the least surface roughness. They also had the lowest material loss in two-body abrasion. The metal dies showed ductile behavior in single-pass sliding.

Calcium Sulfate↗