Effect of water on the physical properties of resin-modified glass ionomer cements.

OBJECTIVES: Resin-modified glass ionomer cements (GIC) are available for clinical use as restorative materials or as liners and bases. This work was conducted to study the effect of water sorption on the physical properties of several resin-modified GIC, by changing the samples' storage conditions. METHODS: The water sorption, the flexural strength, the flexural elastic modulus, the Vickers hardness and the dimensional changes of five resin-modified GICs were measured using specimens aged for 24 h to 3 mon. The specimens were stored at 37 degrees C, either in a dry environment (A), immersed in water (B), stored in a humid environment (C), stored in a humid environment for 1 h and then immersed in water (D), or immersed in water and subsequently dried (B + A). An analysis of variance was used to compare the results. RESULTS: The resin-modified GIC absorb during the first 24 h large amounts of water (114-172 mg/cm3) compared to the conventional GIC (30-63 mg/cm3). Water alters the physical properties of resin-modified GICs: With regard to dry specimens, a decrease in the flexural strength of 20 to 80% was observed for samples immersed in water. Decreases in their flexural elastic modulus (50 to 80%) and in their hardness (approximately 50%) were also observed. Water sorption also provoked an expansion in volume of the immersed specimens, ranging from 3.4 to 11.3% after 24 h. SIGNIFICANCE: The flexural strength and Vickers hardness of the resin-modified GICs are sensitive to the water contained in the tested specimens. A correlation was established between the decrease in their physical properties and the water uptake. However, it should not be concluded that these materials are not adequate for use in applications in direct contact with oral fluids. Probably, resin-modified GIC placed in oral cavities would not be affected to the same extent as in in vitro tests. In an oral environment, the constituents of saliva will certainly decrease the rate of water sorption and will hence delay its effects.     

Effect of adhesive systems associated with resin-modified glass ionomer cements

The bonding of resin-modified glass ionomer cements to dentin remains a challenge in clinical routine. In an attempt to improve this property, different materials and techniques have been proposed. This study investigated the shear bond strength of resin-modified glass ionomer cements (Vitremer, 3M/ESPE and Fuji II LC Improved, GC) to human dentin using two one-bottle adhesive systems (Prime & Bond 2.1, Dentsply and Single Bond, 3M/ESPE). The restored specimens were stored in deionized water for 24 h at 37 +/- 1 degrees C, and then the bonded surfaces were tested in shear strength using a Universal testing machine at a crosshead speed of 0.5 mm min(-1). Bond strength means were recorded and failure modes were assessed with a stereomicroscope at 40x magnification. Data were submitted to two-way anova and multiple comparisons were performed using a Tukey statistical test (P < 0.05). Fuji II LC Improved yielded higher bond strength (P < 0.05) than Vitremer in all experimental conditions. No statistically significant differences (P > 0.05) were observed among the proposed dentin surface treatments, although a slight decrease in bond strength was observed when phosphoric acid was used alone. Bond strengths of the resin-modified glass ionomer cements to dentin seemed to be more material-dependent than surface treatment-dependent. It may be concluded that the one-bottle adhesive systems tested in this study did not improve the bond strength of the resin-modified glass ionomer cements to dentin.     

Porosity in manually and machine mixed resin-modified glass ionomer cements.

The powder and liquid components of resin-modified glass ionomer cements are available in manual and machine mixed forms. This study quantified the effect mixing methods have on the porosity and shear strength of a resin-modified glass ionomer cement (RMGIC). A RMGIC (Fuji II LC) was manually or machined mixed according to manufacturer's instructions. Thin, disc-shaped specimens (n = 5) were made by compressing the cement between glass platens to a thickness of approximately 76 microns. The specimens were light cured for 120 seconds. Digital images of the specimens were recorded using a measuring microscope and slide film scanner. Digital imaging software was used to determine the number and volume of the cement's pores. Shear test specimens of manual and machine mixed cements (n = 10) of each group (approximately 800 microns thickness) were made as previously described. Shear punch tests were conducted using a 3.75 mm diameter punch mounted on a universal testing machine. The mean number and total volume of pores in the manually mixed specimens was considerably greater than that of the machine mixed group (p < 0.05). The shear punch test results of the machine mixed group was significantly higher than the manual mixed group, (p < 0.05).     

Effects of instrumentation time on microleakage of resin-modified glass ionomer cements

This study investigated the effect of instrumentation time on the microleakage of resin-modified glass ionomer cements (RMGICs). Class V cavities were prepared on buccal and lingual/ palatal surfaces of 64 freshly extracted non-carious premolars. The cavities on each tooth were restored with Fuji II LC (FT [GC]) and Photac-Fil Quick (PF [3M-ESPE]). The restored teeth were randomly divided into two groups of 32 teeth. Finishing/polishing was done immediately after light-polymerization in one group and was delayed for one week in the other group. The following finishing/polishing systems were evaluated: (a) Robot Carbides (RC); (b) SuperSnap (SS); (c) OneGloss (OG) and (d) CompoSite Polishers (CS). The sample size for each instrumentation time, material and finishing/polishing system combination was 8. Storage medium for both immediate and delayed instrumentation groups was distilled water at 37 degrees C during the hiatus period. The teeth were subsequently subjected to dye penetration testing (0.5% basic fushcin), sectioned and scored. Data were analyzed using Kruskal-Wallis and Mann-Whitney U tests at significance level 0.05. For PF, significant difference in enamel leakage was observed between immediate and delayed instrumentation with SS and CS. Significant differences in dentin leakage were also observed between the two instrumentation times for SS. For FT, significant differences in leakage between instrumentation times were observed only in dentin and with RC. Where significant differences in dye penetration scores existed, delayed finishing/polishing resulted in less microleakage.     

Effect of region and dentin perfusion on bond strengths of resin-modified glass ionomer cements

OBJECTIVES: The purpose of this study was to evaluate the hypothesis that regional differences and pulpal pressure would significantly affect bond strengths of resin-modified glass ionomer cements to dentin. METHODS: Twenty-six extracted caries-free human third molars were ground to expose middle dentin and were randomly divided into two groups for bonding: no pulpal pressure and pulpal pressure of 15cm H(2)O. Fuji II LC, Vitremer, or Photac-Fil Quick were applied to the previously pre-treated surfaces and light-cured as recommended by the manufacturers. After immersion in water at 37 degrees C for 24h, the teeth were sectioned to 0.7mm thick slabs, divided into pulp horn, center, and peripheral regions according to visual criteria, and trimmed along the bonded interface for microtensile bond test to a cross-sectional area of 1mm(2). The slabs were subjected to tensile forces and the data analyzed using ANOVA and Fisher's PLSD at the 95% level of confidence. RESULTS: For Fuji II LC, bond strengths to the pulp horn regions were significantly lower than those to the other regions independent of pulpal pressure (p<0.05). On the other hand, regional bond strengths were not observed for Vitremer and Photac-fil Quick 0.05). CONCLUSIONS: Pulpal pressure had a stronger influence on bond strengths and failure modes of resin-modified glass ionomers than regional differences of the substrate.     

Effect of various surface protections on the margin microleakage of resin-modified glass ionomer cements

STATEMENT OF PROBLEM: Because conventional glass ionomer cements are moisture sensitive, a surface coating is recommended during the initial setting stage. It is unknown whether resin-modified glass ionomer cements also need surface protection. PURPOSE: This study investigated the effect of various surface protections on microleakage with Class V resin-modified glass ionomer restorations. MATERIAL AND METHODS: Forty extracted molars with buccal and lingual Class V cavity preparations were restored with a resin-modified glass ionomer (Fuji II LC). The occlusal margin of each restoration was on enamel and the cervical margin on dentin. After immediate finishing and polishing, the teeth were divided into 4 groups according to the following surface protection treatments: group I, unprotected; group II, Fuji varnish; group III, resin adhesive; and group IV, acid etching and resin adhesive. After these procedures, all teeth were stored in isotonic saline for 24 hours, thermocycled 1500 times at 5 degrees C to 60 degrees C, and soaked in dye solution for 24 hours. The teeth then were longitudinally sectioned and observed under a stereomicroscope. The degree of dye penetration was recorded and analyzed with the Kruskal-Wallis and Mann-Whitney tests (P<.05) RESULTS: None of the 4 groups demonstrated complete margin sealing at either the occlusal or cervical margins. Groups II and III displayed the least microleakage at cervical margins; a significant difference existed between groups I and III (P=.034). Compared with the other 3 groups, group IV showed significantly greater microleakage at the cervical margins. CONCLUSION: Although resin-modified glass ionomers can be finished immediately, they remain moisture sensitive. Within the limitations of this study, the results suggest that resin adhesive should be used as a surface protection to reduce margin microleakage of resin-modified glass ionomer restorations.     

Shear bond strengths of two resin-modified glass ionomer cements to porcelain.

Shear bond strength of a composite resin adhesive (Concise) and two resin-modified glass ionomer cements (Fuji Ortho LC and Geristore) bonded to porcelain surface was tested. Orthodontic brackets were bonded to 120 porcelain disks (Finesse) etched with 9% HF. Samples were divided into six groups: (1) Concise, (2) Concise/silane, (3) Geristore, (4) Geristore/silane, (5) Fuji, (6) Fuji/silane. No statistical difference in mean shear bond strength was found between silanated Concise (15.8 MPa), Geristore (19.4 MPa), and Fuji (18.5 MPa) groups, which were significantly higher than nonsilanated groups. Porcelain fracture was observed in all silanated groups and nonsilanated Geristore group. We conclude that (1) silane increases bond strength to porcelain significantly for composite resin and resin-modified glass ionomer cement, (2) Concise, Geristore, and Fuji Ortho LC provide comparable shear bond strength to porcelain.     

Selected physical properties of new resin-modified glass ionomer luting cements

Statement of problem

Two resin-modified glass ionomer (RMGI)-based luting agents have been recently marketed without independent reports of their physical properties.

Surface pH of resin-modified glass polyalkenoate (ionomer) cements

The recently developed group of materials known as light-activated, or resin-modified, glass polyalkenoate (ionomer) cements have been produced in response to clinical demands for a command set cavity base material. This study monitored the surface pH of three commercially available resin-modified glass ionomer cements over a 60-min period following either mixing alone or mixing followed by a 30-s exposure to a curing lamp. The results indicate that each material behaves in a unique manner. For all materials and conditions the pH reached after a 60-min period was significantly (P < 0.001) higher than the initial value. Light curing the materials significantly increased (P < 0.01) the surface pH of two of the materials (Baseline VLC and Vitrebond) as compared to the same materials in the uncured state. In the case of XR-Ionomer, however, no significant (P > 0.05) effect of light curing upon the surface pH was apparent. The precise clinical consequences of a low surface pH are unclear but may be an aetiological factor in postoperative pulpal sensitivity. It is therefore recommended that a sublining of a proprietary calcium hydroxide lining material should be placed routinely beneath these materials and every effort made to ensure effective light curing.     

Effect of time on the diametral tensile strength of resin-modified restorative glass ionomer cements and compomer.

The aim of this study was to analyze the diametral tensile strengths of three resin-modified restorative glass ionomer cements--Vitremer, Fuji II LC and Photac Fil and one compomer--Dyract. They were tested at 1 hour, 1 day and 1 week. Kratos testing machine was used to load the specimens at a cross-head speed of 0.5 mm/min. The data were analyzed by two-way ANOVA and Tukey's test that showed statistically significant differences among the materials. The tested materials presented an increase in strength from 1 hour to 1 week and were as follows for each material respectively: Vitremer (19.22-27.29), Fuji II LC (23.91-28.67), Photac Fil (19.35-22.86), Dyract (28.83-46.95). Dyract presented the highest strengths.     

Surface hardness properties of resin-modified glass ionomer cements and polyacid-modified composite resins

In this study the top and bottom surface hardness of two polyacid-modified composite resins (PMCRs), one resin-modified glass ionomer cement (RMGIC), and one composite resin were evaluated. The affect of water storage on their hardness was also investigated. The study was conducted using four different groups, each having five specimens obtained from fiberglass die molds with a diameter of 5 mm and a height of 2 mm. Measurements were made on the top and bottom surface of each specimen and recorded after 24 hours and again at 60 days. All tested materials showed different hardness values, and the values of top surfaces of the specimens were found to be higher than the bottom surface in all test groups. There was no statistical difference in the Vickers hardness (HV) values when the test specimens were kept in water storage. In conclusion Hytac displayed microhardness values higher than Vitremer and Dyract. We found the order of HV values to be Surfil > Hytac > Dyract > Vitremer, respectively. Vitremer presented the lowest microhardness level and Surfil the highest.     

In vitro study of resin-modified glass ionomer cements for cementation of orthodontic bands

The aim of this in vitro study was to investigate different light-cured and chemically cured resin-modified glass ionomer cements used for the cementation of orthodontic bands and to analyze various factors influencing the adhesive strength between enamel, cement and stainless steel.Four resin-modified glass ionomers (Fuji Ortho LC/GC, Fuji Duet/GC, Unitek Multi-Cure Glass lonomer Orthodontic Band Cement/3M Unitek, Vitremer/3M) and 1 compomer (Band-Lok/Reliance) were examined. Flattened and polished bovine teeth embedded in polyurethane resin were used as enamel specimens. Before cementation, 50% of the specimens were moistened with the aerosol of an inhalation device, while the rest were dried with compressed air. Stainless steel cylinders (CrNi 18 10) were perpendicularly bonded onto the polished enamel using a custom-made cementation device and immediately topped with a pressure of 0.25 MPa. The cement was isolated with either Ketac Glaze/ESPE, Fuji Coat/GC, Cacao Butter/GC, Dryfoil/Jalenko or Final Varnish/VOCO, or was left uncoated. Eight minutes after the beginning of mixing, either the surplus cement was removed with a scalpel or surplus removal was simulated with ultrasound. After 24 hours storage in a water bath at 37°C and 1,000 thermocycles the shear bond strength was determined.Significant differences with respect to the shear bond strength were found among the following cements, ranking from highest to lowest: Fuji Duet, Unitek cement>Fuji Ortho LC>Vitremer>Band-Lok. The application of a barrier coating significantly increased the shear bond strength of all cements except Fuji Ortho LC. The light-cured resin Ketac Glaze proved to be the most effective barrier coating. A dry enamel surface increased the bond strength of all investigated cements except Unitek cement. The use of ultrasound led to no significant reduction in shear bond strength in comparison with surplus removal with a scalpel.

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In-vitro-Untersuchung zum Zementleren orthodontischer Bänder mit kunststoffverstärkten GlasionomerzementenIsolierung, Überschußentfernung und Feuchtigkeit als Einflußgrößen auf das Verbundsystem Schmelz-Zement-Metall

Zusammenfassung Ziel dieser In-vitro-Studie was es, verschiedene licht- und chemisch härtende kunststoffverstärkte Glasionomerzemente zum Zementieren von Bändern zu prüfen und verschiedene Einflußgrößen auf das Verbundsystem Schmelz-Zement-Metall zu untersuchen.Vier kunststoffverstärkte Glasionomerzemente (Fuji Ortho LC/GC, Fuji Duet/GC, Unitek Multi-Cure Glass lonomer Orthodontic Band Cement/3M Unitek, Vitremer/3M) und ein Kompomer (Band-Lok/Reliance) wurden untersucht. Als Schmelzproben dienten in Polyurethan eingebettete, planpolierte Rinderzähne. 50% der Proben wurden vor dem Zementieren mit einem Inhalationsgerät befeuchtet, die andere Hälfte der Proben wurde mit Druckluft getrocknet. Stahlzylinder (CrNi 18 10) wurden mittels einer Zementierungshilfe senkrecht auf den polierten Zahnschmelz zementiert und mit einem Druck von 0,25 MPa belastet. Die Zementfuge wurde alternativ mit Ketac Glaze/ESPE, Fuji Coat/GC, Kakaobutter/GC, Dryfoil/Jalenko, Final Varnish/VOCO oder gar nicht isoliert. Acht Minuten nach Anmischbeginn wurden Zementfahnen mittels Skalpell abgeplatzt oder eine Überschußentfernung mit Ultraschall simuliert. Nach 24stündiger Lagerung in 37°C warmem Wasser und 1.000 Temperaturwechseln wurde die Scherfestigkeit ermittelt.Signifikante Unterschiede bezüglich der Scherfestigkeit wurden zwischen folgenden Zementgruppen gefunden: Fuji Duet, Unitek-Zement>Fuji Ortho LC>Vitremer>Band-Lok. Das Verwenden einer Isolierung führte bei allen untersuchten Zementen außer bei Fuji Ortho LC zu einer signifikanten Steigerung der Scherfestigkeit. Der lichthärtende Versiegler Ketac Glaze erwies sich als effektivstes Isoliermittel. Eine trockene Schmelz-oberfläche erhöhte die Verbundfestigkeit der untersuchten Zemente mit Ausnahme des Unitek-Zementes. Die Ultraschallbehandlung führte im Vergleich zur Überschußentfernung mit einem Skalpell zu keiner signifikanten Scherfestigkeitsreduktion.

     

Effect of four silane coupling agents on bonding of two resin-modified glass ionomer cements to a machinable ceramic

The purpose of the present study was to evaluate the effect of four silane coupling agents on the bond strength between two resin-modified glass ionomer cements and a machinable leucite glass ceramic. Ceramic specimens were ground with silicon carbide paper and cleaned with phosphoric acid. They were then conditioned and bonded with combinations of four silane coupling agents (GC Ceramic Primer, Clapearl Bonding Agent, Clearfil Mega Bond Porcelain Bonding Kit, and RelyX Ceramic Primer) and two resin-modified glass ionomer cements (Fuji Luting S and Fuji Lute). Shear bond strength was determined after 24-hour immersion in water or after thermocycling of 50,000 cycles. The results showed that every silane coupling agent significantly improved the bond strength. It was thus recommended that resin-modified glass ionomer cement be applied in conjunction with silane coupling agent when luting ceramic restorations.     

Surface texture of resin-modified glass ionomer cements: effects of finishing/polishing systems

This study investigated the surface texture of two resin-modified glass ionomer cements (RMGICs) in the vertical and horizontal axis after treatment with different finishing/polishing systems. Class V preparations were made on the buccal and lingual/palatal surfaces of freshly extracted teeth. The cavities on each tooth were restored with Fuji II LC (GC) and Photac-Fil Quick (ESPE) according to manufacturers' instructions. Immediately after light-polymerization, gross finishing was done with 8-flute tungsten carbide burs. The teeth were then randomly divided into four groups and finished/polished with (a) Robot Carbides (RC); (b) Super-Snap system (SS); (c) OneGloss (OG) and (d) CompoSite Points (CS). The sample size for each material-finishing/polishing system combination was eight. The mean surface roughness (microm) in vertical (RaV) and horizontal (RaH) axis was measured using a profilometer. Data was subjected to ANOVA/Scheffe's tests and Independent Samples t-test at significance level 0.05. Mean RaV ranged from 0.59-1.31 and 0.83-1.52, while mean RaH ranged from 0.80-1.43 and 0.85-1.58 for Fuji II LC and Photac-Fil, respectively. Results of statistical analysis were as follows: Fuji II LC: RaV-RC, SS相似文献   

Surface finishing of resin-modified glass ionomer

This study utilized spectrophotometry to evaluate in vitro superficial dye deposition on resin-modified glass ionomer, following different surface finishing and polishing treatments. Materials that were photocured adjacent to the mylar strip produced the surfaces with the lowest mean after superficial staining. A restorative technique without excesses resulted in a smoother surface and prolonged the life of the restoration. The resin-modified glass ionomers tested offer adequate clinical performance.     

Microhardness of in vitro caries inhibition zone adjacent to conventional and resin-modified glass ionomer cements.

OBJECTIVE: This study was conducted to correlate Knoop and triangular hardness numbers by measuring the microhardness of in vitro caries-inhibited and -demineralized dentin adjacent to a conventional and two resin-modified glass ionomer cements. METHODS: Box-shaped cavities were prepared on bovine root dentin and restored with either Fuji II, Fuji II LC, or Vitremer. The teeth were then decalcified in an acid buffered solution of 50 mmol l-1 acetic acid adjusted to pH = 4.5 for 3 days. Knoop and triangular microhardness indentations were performed perpendicular to the surface and parallel to the cavity wall, in the demineralized lesion and inhibition zone. Calcium and phosphorous contents of the outer lesions and inhibition zones were compared using energy-dispersive X-ray spectrometry (EDS). The correlation between Knoop and triangular hardness was analyzed by correlation coefficient. The statistical significance of hardness data was analyzed by one-way ANOVA and Fisher's PLSD test (p < 0.05). RESULTS: Triangular hardness (HT) correlated well with Knoop hardness number (KHN) (r2 = 0.81, p < 0.05). The microhardness of the inhibition zone created by Fuji II was of 59.2 +/- 3.8 HT and was statistically significantly higher than the zone produced by Fuji II LC and Vitremer. Fuji II LC and Vitremer produced inhibition zones with similar microhardness [48.3 +/- 3.5 HT and 44.0 +/- 7.6 HT, respectively (p > 0.05)]. Calcium and Phosphorous were present in the inhibition zone, but did not exist in the demineralized lesion. SIGNIFICANCE: Knoop and triangular hardness numbers correlated significantly (p < 0.05), and the latter seems to be a promising alternative method for measuring very narrow surfaces. Despite the fact that all glass ionomer materials used in this study were effective in producing an acid-resistant layer, microhardness and intensity of these layers were material dependent.     

Surface texture of resin-modified glass ionomer cements: effects of finishing/polishing time

This study compared the surface texture of resin-modified glass ionomer cements after immediate and delayed finishing with different finishing/polishing systems. Class V preparations were made on the buccal and lingual/palatal surfaces of 64 freshly extracted teeth. The cavities on each tooth were restored with Fuji II LC (GC) and Photac-Fil Quick (3M-ESPE) according to manufacturers' instructions. Immediately after light-polymerization, gross finishing was done with 8-fluted tungsten carbide burs. The teeth were then randomly divided into four groups of 16 teeth. Half of the teeth in each group were finished immediately, while the remaining half were finished after one-week storage in distilled water at 37 degrees C. The following finishing/polishing systems were employed: (a) Robot Carbides; (b) Super-Snap system; (c) OneGloss and (d) CompoSite Polishers. The mean surface roughness (microm; n=8) in vertical (RaV) and horizontal (RaH) axis was measured using a profilometer. Data was subjected to ANOVA/Scheffe's tests and Independent Samples t-test at significance level 0.05. Ra values were generally lower in both vertical and horizontal axis with delayed finishing/polishing. Although significant differences in RaV and RaH values were observed among several systems with immediate finishing/polishing, only one (Fuji II LC: RaH - Super-Snap < Robot Carbides) was observed with delayed finishing.     

Comparison of pulpal sensitivity between a conventional and two resin-modified glass ionomer luting cements

This clinical study compared handling and any short-term tooth sensitivity associated with using one conventional and two resin-modified glass ionomer cements marketed for luting gold and ceramometal crowns. The patient's response to a 10-second blast of air applied to the vital tooth was scored pre-operatively and again within a one-to-four week post-cementation recall period. A score was also recorded for any sensitivity present at the time of cementation of the crown on the unanesthetized tooth. All three cements were easy to mix and place. Most of the teeth had no response to pulpal stimulation pre-operatively, associated with the cementation procedure or post-cementation, and there were no instances of severe sensitivity recorded. For all cements, the level of post-cementation tooth sensitivity was similar, and less than that found pre-operatively.     

Bond strength for orthodontic brackets contaminated by blood: composite versus resin-modified glass ionomer cements.

PURPOSE: The purpose of this study was to evaluate and compare the shear bond strengths of a self-cured glass ionomer versus composite cement for bonding of stainless steel buttons with various enamel surface and setting conditions. MATERIALS AND METHODS: Stainless steel orthodontic buttons were bonded using composite material under 3 different enamel and setting conditions: 1) conditioned and dry enamel surface, 2) conditioned and precontamination of the enamel surface with blood before bonding, 3) conditioned and immediate blood contamination postbonding and were compared with 3 different enamel conditions and setting for bonding with the glass ionomer cement: 1) nonconditioned and wet enamel surfaces, 2) nonconditioned and blood contamination of enamel before bonding, and 3) nonconditioned and immediate blood contamination postbonding. The brackets were bonded to 109 recently extracted teeth and allowed to set in a moist plastic container for 24 hours. They were subsequently tested in shear mode with a universal testing machine. The maximum bond strength and the site of bond failure were recorded. In addition, the location of the bond failure was studied. RESULTS: Composite was capable of sustaining greater forces than the resin-modified glass ionomer materials. Hence, it took more force to debond a bracket cemented with composite than with resin-modified glass ionomer. The effect of contamination was similar in both of the materials, and the magnitude of the decrease in bond strength was nearly of the same proportion. The postcontamination values were not significantly different from the uncontaminated bond strength for either material. The type of bond failure was significantly different for the different materials, and there were significant differences among the treatment conditions. CONCLUSION: Composite resin had significantly greater shear strength than resin-reinforced glass ionomer cement. Both materials showed a significant decrease in bond strength when precontaminated with blood. The postcontamination values were not significantly different from the uncontaminated bond strength for either material.