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PubMed1991

Microleakage at the resin-alloy interface of chemically retained composite resins for cast restorations.

New retentive mechanisms between veneering resins and casting alloys are claimed to have a chemical bond that results in a high bond strength combined with low microleakage between the veneering resin and cast restoration. This study compared the microleakage of four chemical bonding mechanisms when three veneering resins were bonded to two dental casting alloys. Resin-veneered alloy disks were immersed in red India ink and kept at 37 degrees C for 72 hours. The disks were then bench dried for 24 hours. The resin veneer was sectioned into eight sectors in an engineering milling machine and these resin sectors were removed to display the microleakage pattern. It was concluded that (1) no microleakage was found in two combinations, and (2) the highest microleakage was with Sr-Isosit-N/Panavia EX/Firmilay combinations.

Acrylic Resins↗
PubMed1998

Marginal adaptation and retention of a glass-ionomer, resin-modified glass-ionomers and a polyacid-modified resin composite in cervical Class-V lesions.

OBJECTIVES: An 18-month follow-up clinical trial of one conventional glass-ionomer (HIFI Master Palette), three resin-modified glass-ionomers (Fuji II LC, Vitremer, 3M Exp. 155) and one polyacid-modified resin composite (Dyract) was conducted to evaluate their clinical effectiveness in Class-V cervical lesions. In addition, the interface between dentin and two resin-modified glass-ionomers and one polyacid-modified resin composite was examined by scanning electron microscopy (SEM). METHODS: After evaluation of the restorations immediately following placement (baseline), all patients were subjected to a strict recall schedule with controls at 6, 12 and 18 months. The clinical effectiveness was recorded in terms of retention and marginal integrity, clinical microleakage, caries recurrence, and tooth vitality. A chi 2-test (p < 0.05) was used to test for significant differences between materials. In case of restoration loss or special defects, a replica was made to examine the surface texture and restoration margins by SEM. In vitro, the interface was examined by SEM after an argon-ion-beam etching technique was used to enhance surface relief and disclose interfacial substructures. RESULTS: Retention appeared to be good for all the materials tested. Marginal discrepancies were localized at the incisal enamel and/or the cervical dentin margin, except for the polyacid-modified resin composite that showed most of the defects at the incisal enamel margin. None of the systems could guarantee margins free of microleakage for a long time. In vitro, the type of dentin pre-treatment defines to a great extent the morphology of the resultant interface between dentin and the restorative material tested. SIGNIFICANCE: In this clinical study, the retention rate of the tested materials was good and even excellent for some products. Perfect marginal adaptation deteriorated too fast. The marginal adaptation of the polyacid-modified resin composite at the enamel site would probably have been better by the use of selective enamel or total acid etching. Marginal sealing remains a problem. Future research should concentrate on improving the marginal adaptation and sealing capacities before a broader clinical use can be advocated.

Acrylic Resins↗
PubMed2003

Effect of simulated resin-bonded fixed partial denture clinical conditions on resin cement mechanical properties.

The purpose of this study was to determine changes in flexural properties of resin cement under simulated resin-bonded fixed partial denture (RBFPD) clinical conditions using aqueous ageing and cyclic loading. Panavia F flexural modulus and strength were measured by static loading to failure after 48-h and 60-day aqueous ageing at 37 degrees C with and without simulated cyclic occlusal loading. Panavia F sorption and solubility were also measured. Scanning electron microscopy (SEM) was used to characterize the morphology of the fractured surfaces. A two-factor anova (P </= 0.05) indicated that cyclic loading produced a significant increase in the flexural modulus with no significant effect on the flexural strength. Conversely, aqueous ageing time produced a significant decrease in flexural strength with no effect on the flexural modulus. The SEM fracture analysis indicated that resin matrix fracture occurred in static-aqueous specimens; while in the aqueous-cycled specimens, resin matrix fracture occurred in addition to an increasing proportion of filler/resin interface fracture. Collectively, these outcomes suggest that initial degradation under simulated resin cement clinical function may be related to breakdown of the filler/resin interface bond, which could contribute to in vivo RBFPD resin cement cohesive failure.

Analysis of Variance↗
PubMed2001

Effects of conventional and high-intensity light-curing on enamel shear bond strength of composite resin and resin-modified glass-ionomer.

The purpose of this study was to evaluate the shear bond strengths of a composite resin (Transbond XT; 3M/Unitek, Monrovia, Calif) and a resin-modified glass ionomer (Fuji Ortho LC; GC America Inc, Alsip, Ill) cured with 2 different light-curing units: a conventional visible light unit (Ortholux XT; 3M Dental Products, St Paul, Minn) and a xenon arc light unit (Plasma Arc Curing [PAC] System; American Dental Technologies, Corpus Christi, Texas). One hundred twenty freshly extracted bovine permanent mandibular incisors were randomly divided into 1 of 8 groups; each group consisted of 15 specimens. Two groups (1 group for each type of adhesive) were exposed to the visible light for 20 seconds (Transbond XT) and 40 seconds (Fuji Ortho LC), respectively, and used as control groups. The remaining 6 groups (3 for each adhesive) were cured with the xenon arc light for 2, 5, and 10 seconds. After bonding, all samples were stored in distilled water at room temperature for 24 hours and subsequently tested in a shear mode on an Instron universal testing machine (Instron Corp, Canton, Mass). For the groups bonded with Transbond XT, no statistically significant differences (P =.868) were found between the shear bond strength of the control group cured with Ortholux XT and those of the groups cured with the PAC System for 2, 5, or 10 seconds. When the shear bond strengths of the groups bonded with Fuji Ortho LC were evaluated, no statistically significant differences (P =.087) were found between the control group that was cured with Ortholux XT and those cured with the PAC System. The bond strength of the composite resin was significantly higher than that of the resin-modified glass ionomer in all the groups tested (P <.0001). The present findings indicate that, compared with visible light-curing, the xenon arc light enables the clinician to significantly reduce the curing time of both bonding agents, without affecting their shear bond strengths. Therefore, xenon arc light sources can be recommended as an advantageous alternative for curing both composite resins and resin-modified glass ionomers.

Acid Etching, Dental↗
PubMed1996

Effect of resinous temporary material on tensile bond strength of resin luting cement to tooth substrate.

We investigated the effect of resinous temporary material on the tensile bond strength of resin luting cement to enamel and to dentin. Four hundred bovine incisor teeth were randomly divided into groups. Four resinous temporary materials and four resin luting cements were used. On enamel, none of the resinous temporary materials decreased the tensile bond strength of the cements. On dentin, all the resinous temporary materials decreased the tensile bond strength of the cements except one containing 4-META/MMA-TBB.

Animals↗
PubMed1999

Evaluation of esthetic parameters of resin-modified glass-ionomer materials and a polyacid-modified resin composite in Class V cervical lesions.

OBJECTIVE: The purpose of this study was to compare the esthetics of 3 resin-modified glass-ionomer materials and 1 polyacid-modified resin composite to the esthetics of a conventional glass-ionomer control material. METHOD AND MATERIALS: One hundred eighty-seven Class V cervical restorations were observed clinically over 18 months. The esthetic index system that was used evaluated color match, translucency or opacity, and surface roughness. RESULTS: The tested materials behaved very dissimilarly and inconsistently. In general, the esthetic results of the resin-modified glass-ionomer materials and the polyacid-modified resin composite were far from optimal. The esthetic appearance of restorations seriously deteriorated during clinical service, mainly because of discoloration of margins, changes in translucency and opacity, and rapidly appearing roughness or dullness on the surface. Both the resin-modified glass-ionomer materials and the polyacid-modified resin composite evaluated in this study performed better esthetically than did the conventional glass-ionomer material. CONCLUSION: Indications for these combination materials are limited to areas where esthetics is not a primary concern but where their ease of application may guarantee a more durable functional result.

Acrylic Resins↗
PubMedDate not supplied

Two-year clinical performance of Class V resin-modified glass-lonomer and resin composite restorations.

While a one-year report had been previously published, this study was undertaken to evaluate the clinical performance and appearance of a resin-modified glass ionomer and a resin composite over two years. Thirty-seven pairs of restorations of FujI II LC and Z 250/Single Bond were placed in caries-free cervical erosion/abfraction lesions without tooth preparation. Restorations were clinically evaluated at baseline, 6, 12, 18 and 24 months using modified Ryge/USPHS criteria. No statistically significant difference (p = 0.13) was observed in the overall performance of the materials. Retention was 96% for the resin-modified glass ionomer and 81% for the resin composite, with no additional restorations of either material lost after one year. As previously reported, retention of the Z 250 restorations at six months was below the minimum specified in the ADA Acceptance Program for Dentin and Enamel Adhesives. The resin composite restorations generally had a better appearance, with a 100% alpha rating in color match, versus 85% for the resin-modified glass ionomer.

Adult↗
PubMed1990

[Durability of commercial composite resin. Chronological change in transverse strength and transverse elastic modulus of composite resin immersed in MeOH].

The durability of visible light-cured composite resin was examined. Five kinds of commercial redox type composite resin and 7 kinds of visible light-cured composite resin were used and their base monomers were analyzed by HPLC. After the set products were immersed in MeOH, transverse strength and transverse elastic modulus were measured. Furthermore, the MeOH sorption, solubility in MeOH and main soluble component were examined. The main component of the base monomer in all 5 kinds of redox type was Bis-GMA. Seven kinds of visible light-cured composite resin consisted of 4 kinds of Bis-GMA (including BMPEPP) and 3 kinds of UDMA. Both cases of redox type and visible light-cured type of composite resin, when they were immersed in MeOH, transverse strength and transverse elastic modulus decreased. In the case of redox type (Clearfil posterior new bond), the decrease of transverse strength and transverse elastic modulus was small, that is, its base monomer was Bis-GMA, and large quantities of hybrid type filler were mixed. In the case of redox type, transverse strength and transverse elastic modulus showed a tendency to decrease with the increase of MeOH sorption. Solubility of 12 kinds of these composite resins was 0.25-4.78% and its main component in Pyrofil light bond A was BMPEPP, the residual were coincident with the main component of base monomer.

Absorption↗
PubMed1997

Post-irradiation hardness of resin-modified glass ionomer cements and a polyacid-modified composite resin.

This study examined the post-irradiation hardness of resin-modified glass ionomer cements and a polyacid-modified composite resin using a digital microhardness tester. Change in hardness of these materials over a period of 6 months was compared to that of conventional glass ionomer cements and a composite resin. With the exception of the composite resin, all materials showed a significant increase in hardness over 24 h after their initial set. Dual-cure resin-modified glass ionomer cements showed decreased hardness with increased storage time in saline at 37 degrees C. Results suggest that the addition of resins to glass ionomer cements does not improve initial hardness and does not negate the acid-base reaction of conventional cements. Resin addition may, however, lead to increased water sorption and decreased hardness.

Journal Article↗
PubMed2002

Studies on MMA-tBB resin. I. Comparison of TBB and other initiators in the polymerization of PMMA/MMA resin.

Polymerization characteristics of poly (methyl methacrylate)(PMMA)/(methyl methacrylate) (MMA) resin initiated by tributylborane (TBB) were compared with those by benzoyl peroxide (BPO)/N,N-dimethyl-p-toluidine and camphorquinone (CQ)/N,N-dimethylaminoethyl methacrylate from the aspects of temporal changes of residual MMA and molecular weight up to 4 weeks at 37 degrees C. Residual MMA 30 min after polymerization decreased from 8.15% for TBB resin, 8.39% for the BPO resin, and 9.19% for the CQ resin to 0.48%, 3.54%, and 6.79%, respectively, after 4 weeks. The molecular weights at 30 min and 4 weeks after polymerization were 409 x 10(3) and 247 x 10(3) for TBB resin, 297 x 10(3) and 282 x 10(3) for the BPO resin, and 267 x 10(3) and 231 x 10(3) for the CQ resin, respectively. The present results revealed that the TBB-initiated polymerization had unique and different characteristics compared with those initiated by the other common initiators: (1) The decrease in residual MMA was fast, sustained for a long time and resulted in very low value; (2) high molecular weight PMMA was formed first and then decreased with time.

Analysis of Variance↗
PubMed1997

Effect of convergence angle on retention of resin-bonded retainers cemented with resinous cements.

STATEMENT OF PROBLEM: Poor retention is a common cause of failure for resin-bonded restorations. PURPOSE: This study evaluated the effect of the convergence angle of tooth preparations on retention of resin-bonded restorations, luted with adhesive and conventional resinous cements. MATERIAL AND METHODS: A total of 80 posterior retainers with four different tooth preparation angles were cemented with two different resinous cements, and retentive strength was measured. RESULTS: The results indicated that (1) increased tapering of tooth preparations resulted in loss of retention and this variable was statistically significant for both cements used when convergence angles exceeded 10 degrees and (2) sandblasted nickel-chromium retainers, combined with adhesive resins, should provide sufficient retention for posterior resin-bonded fixed partial dentures.

Adhesives↗
PubMed2001

Mode of failure in the dentin-adhesive resin-resin composite bonded joint as determined by strength-based (muTBS) and fracture-based (CNSB) mechanical testing.

OBJECTIVE: To determine the failure mode between dentin-adhesive resin-resin composite bonded joint produced with a chevron-notch short-bar (CNSB) and microtensile test methods. METHODS: Forty teeth were randomly selected for microtensile and forty for CNSB specimen fabrication and stored in 0.5% chloramine T at 37 degrees C until respective static load to failure testing at 30 and 180days. Failure modes were categorized by SEM and tested with Fisher's exact test. Within respective mechanical testing methods the probability of failure curve distributions being significantly different were analyzed by the Wald chi-square statistic. RESULTS: The characteristic fracture toughness at 30- and 180-day storage was 0.82 and 0.87MPam(1/2), while the Weibull Modulus (m) for the failure distributions, was 4.60 and 4.56, respectively. No significant difference was demonstrated in the failure distributions between these groups (p=0.45). The characteristic tensile strength (muTBS(o)) at 30- and 180-day storage was 52.53 and 14.71MPa with an m of 3.04 and 1.56, respectively. Failure distributions for muTBS groups were significantly different (p<0.001). K(IvM) failure modes, regardless of storage time, were within the adhesive joint with 30-day debonds primarily through the top region of the hybrid layer (THL) and after 180-days involving the bottom of the hybrid layer (BHL). The 30-day muTBS group demonstrated a propensity to debond in dentin or resin composite substrates but after 180-days storage debonds again involved the BHL. SIGNIFICANCE: The weak links in the dentin-adhesive resin-resin composite bonded joint may be the interphase regions between the THL and the adhesive resin and the BHL and dentin.

Adhesiveness↗
PubMed2002

Micro-tensile bond testing of resin cements to dentin and an indirect resin composite.

OBJECTIVES: Micro-tensile bond strength (microTBS) evaluation and fractographic analysis were used to compare four resin cement systems (AC: All-Bond 2/Choice; RX: Single Bond/RelyX ARC; SB: Super-Bond C & B; and PF: Panavia F) in indirect composite/dentin adhesive joints. METHODS: Flat dentin surfaces were created on extracted human third molars. The resin cements were used according to the manufacturers' instructions for bonding silanized composite overlays to deep coronal dentin. 0.9x0.9 composite-dentin beams prepared from the luted specimens were stressed to failure in tension. Dentin sides of all fractured specimens were examined by scanning electron microscopy (SEM) to examine the failure modes. In group PF, morphologic features that could not be resolved at the SEM level were further validated by transmission electron microscopy (TEM) examination of the SEM specimens. RESULTS: Statistical analyses revealed significant difference (p<0.05) among microTBS and failure modes in the resin cement groups. The two groups (AC and RX) with highest microTBS failed predominantly along the composite overlay/cement interface. Cohesive failure in resin cement was primarily observed in group SB that exhibited intermediate microTBS values. In group PF with the lowest microTBS, failure occurred mostly along the dentin surface. Globular resin agglomerates seen by SEM on PF-treated dentin were distinguished from silica fillers by TEM. SIGNIFICANCE: The bond between the processed composite and the luting resin cement was the weak link in indirect composite restorations cemented with AC or RX. Super-Bond C&B exhibited intermediate tensile strength and Panavia F is less reliable when used in conjunction with a self-etching primer for bonding indirect restorations to dentin.

Analysis of Variance↗
PubMed2002

The effects of eugenol and epoxy-resin on the strength of a hybrid composite resin.

The compatibility of different dental materials (root canal sealer and composite core build-up restoratives) is an important factor for a successful restoration. The aim of this in vitro study was to determine the effects on compressive and diametral tensile strength of a classical chemical cure composite resin (Henry Schein Composite Anterior-Posterior dental restorative) when in contact with either eugenol or an epoxy-resin (EZ-Fill) in a variety of situations: (a) eugenol or epoxy-resin added during mixing of a composite resin before curing; (b) vapor exposure to cured samples; and (c) specimens placed directly in eugenol or epoxy-resin (after curing). Compressive strengths and diametral tensile strengths were tested for each group. Only the addition of eugenol during mixing with the composite resin (directly before curing) resulted in specimens that were unable to be tested, because they did not achieve a full cure or hardness. For all other groups, there were no significant differences with respect to either compressive strength (p = 0.17) or diametral tensile strength (p = 0.39). Group 1 (mixed directly with eugenol) was found to be statistically different from groups 2 through 7.

Analysis of Variance↗
PubMed2005

Flexural strengths of denture base resin repaired with autopolymerizing resin and reinforcements after thermocycle stressing.

PURPOSE: Fracture of an acrylic denture base is a common problem in prosthodontic practice. Although various reinforcement methods have been used, when a fractured denture base is repaired with autopolymerizing resin recurrent fractures frequently occur at the repairing interface or adjacent areas. The purpose of this study was to evaluate the maximum flexural load of denture base resin repaired with autopolymerizing resin and several reinforcement systems after thermocycle stressing. MATERIALS AND METHODS: Rectangular (10 x 70 x 3 mm) flexural specimens were fabricated by repairing a pair of heat-cured denture base resin specimens using autopolymerizing resin and a series of reinforcement materials. The materials included 4 metal wires and a woven glass fiber. Each reinforcement was embedded in the center of the specimens. Flexural specimens repaired without reinforcement were prepared as controls. Specimens were subjected to 50,000 thermocycles (4 approximately 60 degrees C, 1-minute dwell time). A 3-point flexural test was carried out by loading the center of the repaired site at 5 mm/minute crosshead speed with 50 mm span jig supports. The load necessary to cause fracture was recorded for each specimen. All data were statistically analyzed using ANOVA and the Bonferroni/Dunn test (alpha < 0.05). RESULTS: The average load to fracture of specimens repaired with nonreinforced autopolymerizing resin was 68.4 N after 50,000 thermocycles. Specimens reinforced with 1.2 mm diameter stainless steel wire exhibited the highest value (89.8 N). The value for specimens reinforced with 1.2 mm diameter Co-Cr-Ni wire was 86.6 N. These fracture loads were significantly higher than those for specimens without reinforcement (p < 0.05). Low elasticity reinforcement, such as pure titanium wires, woven metal wire, and woven glass fiber were not effective in increasing the load to fracture values of flexural specimens. CONCLUSIONS: Specimens reinforced with 1.2 mm diameter stainless steel wires or Co-Cr-Ni wires resulted in significantly higher loads to fracture as compared to specimens without reinforcement. The use of pure titanium wire, woven metal wire, and woven glass fiber did not improve the fracture loads.

Acrylic Resins↗
PubMedDate not supplied

Clinical performance of Class II restorations in which resin composite is laminated over resin-modified glass-ionomer.

This study evaluated the one-year functioning of resin-composite/resin-modified glass-ionomer open-laminate restorations when used for restoring Class II cavities. It also investigated the effect of the thickness of the resin composite layer on the performance of such restorations. The test restorations were made of Vitremer glass ionomer, Scotchbond Multipurpose Plus and Z100 resin composite, and the control restorations were made of Z100 with Scotchbond Multipurpose Plus. Forty pairs of restorations were placed in 40 patients aged 16 years and over. The thickness of the resin composite layer was measured both clinically and in the laboratory using a reflex microscope. The completed restorations were assessed in vivo and in vitro at baseline, six-month and one-year recalls using a modified Ryge system. The reflex microscope measurements showed that the majority of restorations had a resin composite layer of more than 1.5 mm in thickness, as intended. At one year, 37 pairs of restorations were examined. Apart from a few minor problems, all performed satisfactorily. Thus, it appears that the resin composite/resin modified glass ionomer open laminate is a suitable technique for restoring Class II cavities.

Adolescent↗
PubMed2004

Effects of light intensity through resin inlays on the bond strength of dual-cured resin cement.

PURPOSE: To evaluate the influence of the light intensity, irradiation time, and thickness of the indirect restoration composite on the bond strength of dual-cured resin cement immediately after cementation, applying the resin coating technique. MATERIALS AND METHODS: Three hundred forty composite blocks as an adhesive surface and four thicknesses of indirect restoration composite disks were prepared. The surface of the composite blocks was coated with low-viscosity resin composite and immersed in water for 24 h. After immersion, dual-cured resin cement was applied to the resin-coated surface and the indirect restoration composite disks were placed on it. Light irradiation was performed through four thicknesses of indirect restoration composite disks with conventional halogen (40 s) and high intensity (10, 20, 40 s) light units. The specimens were stored in water at 37 degrees C for 10 min or 24 h, and the tensile bond test was performed. RESULTS: For the 1-mm composite thickness, there were no significant differences in the bond strengths between 10 min and 24 h after cementation with the four light curing methods. For the composite thicknesses of 3 or 4 mm, the bond strength 24 h after cementation was significantly higher than that at 10 min after cementation with conventional halogen (40 s) and high-intensity light units at 10 s and 20 s, but there was no significant difference with the high-intensity light unit applied for 40 s. CONCLUSION: The bond strength of dual-cured resin cement immediately after cementation could be greatly influenced by the irradiation time and the light intensity penetrating the indirect restoration composite.

Analysis of Variance↗
PubMedDate not supplied

Curing depth of a resin-modified glass ionomer and two resin-based luting agents.

The degree of conversion of resin-based luting agents used for retention of prefabricated posts has been questioned due to the difficulty of light penetration into the resin-filled root canal. This study evaluated the depth of cure of a resin-modified glass ionomer cement (Rely X--3M ESPE) and two resin-based luting agents (Rely X ARC--3M ESPE and Enforce-Dentsply). Twenty-four 14x2x2mm3 specimens were prepared in a Teflon split mold with the three luting agents (n=8). After preparation, the specimens were stored at 37 degrees C in a dark box for 24 hours prior to microhardness testing. Measurements of Knoop hardness were performed at three different depths: superficial, medium and deep thirds. The results (KHN) were statistically analyzed by repeated measures ANOVA and Tukey test (0.05), which showed that resin-based luting agents presented the highest Knoop hardness values within the superficial third. Within the medium third, there were no significant differences among luting materials. However, within the deep third, Rely X presented the highest values. KHN values of resin-based luting agents decreased remarkably as depth increased.

Bisphenol A-Glycidyl Methacrylate↗