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PubMed1992

Shear strength of laboratory-processed composite resins bonded to a silane-coated nickel-chromium-beryllium alloy.

The shear bond strengths of three commercial laboratory curing composite resin veneers bonded to a nickel-chromium-beryllium alloy treated with the Silicoater system were evaluated. Two light-cured resins and one heat- and pressure-cured resin were evaluated. No statistically significant difference in bond strengths among the three resins was found. Microscopic analysis of the fracture surfaces indicated that all failures were complex and cohesive in nature within the resin and composite. On the basis of the shear bond strengths measured, any of the composite resin veneers tested appear to be clinically acceptable.

Acrylic Resins↗
PubMed2001

Interfacial shear strengths of dental resin-glass fibers by the microbond test.

OBJECTIVES: The aim of this study was to investigate the feasibility of using the microbond test (MBT) to probe the durability of the bond between a polymerized dental resin with differently silanized E-glass fibers. METHODS: The E-glass fibers were silanized with equivalent amounts of two types of acrylic-silane coupling agents: 3-methacryloxypropyltrimethoxysilane (MPTMS) and 10-methacryloxydecyltrimethoxysilane (MDTMS), a more hydrophobic silane coupling agent than MPTMS. Unsilanized E-glass fibers were used as the control. Microdroplets of a photo-activated dental resin were applied on the fiber and photocured with visible light irradiation (470 nm). Subsequently, the specimens were tested in shear after 24h storage in air at 23 degrees C or water at 60 degrees C. RESULTS: The mean interfacial shear strength (tau) and the standard deviation in MPa for the three systems in 23 degrees C in air (n>7) were: 33.8(10.1), 33.7(8.9) and 15.3(4.2) for the MPTMS silanized, MDTMS silanized, and unsilanized fibers, respectively. When the three types of fibers were first exposed to 60 degrees C water for 24h prior to having the microdroplets of the resin bonded to them, the strength values of the MDTMS silanized fibers and the control fibers remained essentially unchanged at (n> or =7) 31.8(7.7) and 17.5(4.9)MPa respectively; the MPTMS specimens showed a significant decrease to 15.8(4.8)MPa. Similar trends were observed when the fibers had microdroplets of the resin bonded to them prior to aqueous exposure. SIGNIFICANCE: These results indicate that the microbond test has the sensitivity to measure changes at the interface between polymerized dental resins and variously silanized E-glass fibers. It appears that surface modification of the fibers with the more hydrophobic silane coupling agent MDTMS promotes enhanced resistance to degradation from exposure to water. The microbond test has the potential for studying dental adhesion involving small bonded areas under a variety of conditions with different adhesive systems and substrates.

Composite Resins↗
PubMed2001

Deep soil compaction as a method of ground improvement and to stabilization of wastes and slopes with danger of liquefaction, determining the modulus of deformation and shear strength parameters of loose rock.

For the stabilization of dumps with the construction of hidden dams and for building ground improvement, for instance for traffic lines over dumps, nearly all applied compaction methods have the aim to reduce the pore volume in the loose rock. With these methods, a homogenization of the compacted loose rock will be obtained too. The compaction methods of weight compaction by falling weight, compaction by vibration and compaction by blasting have been introduced, and their applications and efficiencies have been shown. For the estimation of the effective depth of the compaction and for a safe planning of the bearing layer, respectively, the necessary material parameters have to be determined for each deep compaction method. Proposals for the determination of these parameters have been made within this paper. In connection with the stabilization of flow-slide-prone dump slopes, as well as for the improvement of dump areas for the use as building ground, it is necessary to assess the deformation behavior and the bearing capacity. To assess the resulting building ground improvement, deformation indexes (assessment of the flow-prone layer) and strength indexes (assessment of the bearing capacity) have to be determined with soil mechanical tests. Förster and Lersow, [Patentschrift DE 197 17 988. Verfahren, auf der Grundlage last- und/oder weggesteuerter Plattendruckversuche auf der Bohrlochsohle, zur Ermittlung des Spannungs-Verformungs-Verhaltens und/oder von Deformationsmoduln und/oder von Festigkeitseigenschaften in verschiedenen Tiefen insbesondere von Lockergesteinen und von Deponiekörpern in situ; Förster W, Lersow M. Plattendruckversuch auf der Bohrlochsohle, Ermittlung des Spannungs-Verformungs-Verhaltens von Lockergestein und Deponiematerial Braunkohle--Surface Mining, 1998;50(4): 369-77; Lersow M. Verfahren zur Ermittlung von Scherfestigkeitsparametern von Lockergestein und Deponiematerial aus Plattendruckversuchen auf der Bohrlochsohle. Braunkohle--Surface Mining, 1995;51(1):39-47] improved a direct procedure, the so-called plate-loading test. With this improved procedure, it is possible to produce profiles of deformation parameters and shear-strength parameters of the loose rock. On this basis the settlement behavior and the bearing behavior of the ground can be described. The PDV-BS cone-penetration test and the pressiometer test are compared and the reliability of the soil mechanical indexes are assessed critically. The PDV-BS can be used as a calibration test for cone penetration tests as well as for the calibration of pressiometer tests. With the application of a PDV-BS and a pressiometer test in combination in a testing field, the anisotropy properties of the loose rock can be proved.

Anisotropy↗
PubMed1990

[The shearing strength with the silicoater procedure of conditioned bonded retaining elements].

The shear-bond strength of 120 sandblasted and silicoated metal elements (Wiron 88, Ni-Cr alloy) bonded with three different composites (ABC-cement, Superbond, Comspan opaque) to the plane of the prepared enamel surface of extracted teeth was measured. The effect of the interval between silicoating and bonding and that of 30 days' water storage was evaluated. The silicoating technique resulted in significantly higher bond strength than pure sandblasting, regardless of the composites used. After a one-day water storage the lowest bond strength was obtained with ABC-Cement and the highest with Superbond and Comspan opaque, independent of the interval between silicoating and bonding. After 30 days water storage elements bonded 30 min or 4 to 5 h after the silicoating procedure showed a loss of bond strength of an average of 25% regardless of the composites used. This decrease could not be measured with silicoated metal elements which were preserved by application of a bonding agent and bonded 24 h later.

Dental Alloys↗
PubMed1993

[The shear strength of dentin-bonding agents under intrapulpal pressure and temperature change. An in-vitro study].

This in-vitro study reports on a modified method for testing shear bond strength of dentin bonding agents (DBA's). For a better imitation of the surface of vital human dentin, all DBA's used in this investigation (12 commercially available and one experimental) were tested with dentin under intrapulpal pressure (19.6 cm/36 cm H2O) and exposed to thermal cycling (x1500, 5 degrees C/55 degrees C). In group A the bonding agent was light cured before the application of the composite resin. In group B the bonding agent and the composite resin were light cured at the same time. The difference between the modified testing method and a commonly used method (application of the DBA onto a dry dentinal surface, water storage at 37 degrees C for 24 h) was significant (p < 0.001, ANOVA two way). The shear bond strengths recorded with our method were generally lower than formerly published results. A.R.T. Bond and Experimental had the best average results in both testing groups. Superbond C&B bond strength had to be interpreted separately.

Analysis of Variance↗
PubMedDate not supplied

Dentin bond shear strength and microleakage for Syntac/Heliomolar: a comparison between the manufacturer's and total etch technique.

Recent improvements in formulation have led to significant improvements in the bond strength and clinical performance of dentin bonding agents. The growing interest in the concept of total etch prompted a comparison between manufacturer-recommended procedure and that of total etch for the product Syntac. An in vitro study to examine shear bond strength to dentin and microleakage and an in vivo component to investigate the micromorphologic relationship between restoration and tissue was conducted. No statistical significance was observed in bond strength values for the nonetched versus the etched group. Significantly, however, a larger number of specimens in the nonetched group exhibited microleakage. In vivo, only the etched group exhibited a zone of hybridization although both nonetched and etched restorations showed no interfacial gaps. It was concluded that total etch does not compromise the shear bond strength of Syntac but it appears to significantly reduce microleakage possibly due to the formation of a hybrid zone and may have merit clinically.

Acid Etching, Dental↗
PubMed1989

The effect of various surface treatments on the shear strength between composite resin and glass-ionomer cement.

The effect of various surface treatments on the shear bond strength of composite resin to a glass-ionomer cement has been studied. Acid etching with phosphoric acid and polyacrylic acid, roughening by way of grinding or air drying, the use of a dentine bonding system and a silane coupling agent were the variables. Acid etching, grinding or air drying the surface of the cement had a significant effect on the bond strength. The use of a dentine bonding system led to a significant improvement in the resulting bonding. Silane coupling agent did not improve the bonding. Composite resin did not adhere to a smooth cement surface, but the application of the dentine bonding system on such a surface produced a moderate bond.

Acid Etching, Dental↗
PubMed1983

Strength testing of dental stone: a comparison of compressive, tensile, transverse, and shear strength tests.

The strength of two dental stones under three standard test regimens and two novel testing modes is reported. It was found under all test regimens that the water/powder ratio significantly affected the strength of the two gypsum products in a similar manner. It was established that the new central fulcrum loading mode gave strength data directly related to that determined in the conventional transverse strength test which requires larger test specimens.

Calcium Sulfate↗
PubMed2001

[Shear strength of bond of the dentin to GI-II glass-infiltrated alumia ceramic agter varying modes of surface conditioning].

OBJECTIVE: The adequate surface conditioning method for GI-II glass infiltrated alumia ceramic was investigated. METHODS: The test specimens were divided into 3 groups (A. HF + silicon, B. sandblasting + silicone and C. thermal silicoating + silicone). Shear bonding strengths of porcelain bonded to dentin were tested. RESULTS: The bond strength of group A and B slightly increased after one day but decreased sharply after 30 days. However, no statistical significance was observed. The group C showed a pronounced enlargement of bond strength after one day and had a durable bond after 30 days' thermal cycling. It is statistically significant when group C was compared with group A and B. CONCLUSION: It can be inferred that silicoating method be a better way for glass infiltrated alumia ceramic bonding.

Aluminum Oxide↗
PubMed1995

Shear strength of ceramic brackets bonded to etched or unetched enamel.

The purpose of this study was to compare the shear bond strengths and enamel surface morphology after debonding a polycrystalline ceramic bracket (Transcend 2000) bonded with a light-cured resin cement (Transbond) without enamel etching or by etching for 15 seconds with 10% or 37% phosphoric acid and 10% maleic acid. Forty extracted noncarious human premolars were used. The buccal enamel surfaces were used and the teeth randomly divided in to four groups of 10 teeth each: Group 1: No enamel etching; Group 2: Enamel etching for 15 seconds with 10% phosphoric acid; Group 3: Enamel etching for 15 seconds with 37% phosphoric acid; and Group 4: Enamel etching for 15 seconds with 10% maleic acid. The brackets were bonded to the etched enamel surfaces according to manufacturers' instructions except the etching time variations. All specimens were stored in distilled water for 24 hours and then thermocycled for 300 cycles between 5 degrees C and 55 degrees C. The specimens were mounted in dental stone and placed in the Instron at a crosshead speed of 0.5 mm/min using a knife-edged blade. Immediately after debonding, the enamel surface and bracket-enamel interface were evaluated visually and with a stereomicroscope. Representative samples were then examined with the SEM. ANOVA and Student-Newman-Keuls tests were performed. The results (in MPa) were: Group 1:11.83 (+3.9); Group 2: 28.80 (+12.6); Group 3: 26.25 (+5.3); Group 4: 18.06 (+6.9). Groups 2 and 3 were statistically significantly different (p<0.0001) from Groups 1 and 4. Groups 2 vs. 3 or 1 vs. 4 were not statistically different. Debonding occurred mainly at the bracket-resin interface in all groups, except Group 2 which displayed two samples with enamel cohesive failures and two fracturing the bracket. The SEM evaluation revealed that after debonding, the group etched with the 37% phosphoric acid gel had the roughest enamel surface and was the only group to present enamel fractures. Bracket bonding with unetched enamel and enamel etched with 10% phosphoric acid gel should be clinically investigated using the products tested.

Acid Etching, Dental↗
PubMed1993

Shear strength and microleakage of light-cured glass ionomers.

Bond to dentin and marginal integrity of three light activated glass ionomer cements were evaluated, and compared to a traditional chemical-cured glass ionomer cement. Results indicated no significant difference in shear bond strength among the glass ionomer cements tested. However, there was a significant difference among glass ionomer cements in bond strength variability, with coefficients of variation ranging from 55 to 102%. A discrepancy between manufacturers' instructions and optimum curing times is one possible explanation for these results. There were also no significant differences in microleakage among glass ionomer cements. Most samples exhibited minimal or no microleakage.

Analysis of Variance↗
PubMed1992

Shear strength of resin developed by four bonding agents used with cast metal restorations.

The evolution of the acid etch technique has made possible a more conservative approach to the fabrication of cast metal restorations. The resin bonding technique, however, places a greater burden for success on the selection of a bonding agent. This study examined the shear bond strength durability of cast metal restorations bonded to tooth structure with one of four metal adhesive bonding agents. Results indicated stronger bonds for restorations cemented with Panavia EX bonding agent than with any of the other bonding agents tested, both with and without exposure to thermal stress. Although it was one of the easier materials with which to work, Panavia EX bonding agent requires the additional step of applying an agent to prevent oxygen contact in the setting process.

Acid Etching, Dental↗
PubMed1994

Shear strength of composite bonded porcelain-to-porcelain in a new repair system.

This study assesses the repair procedure for porcelain fracture and involves fitting and bonding a porcelain material over the original damaged crown. To simulate the situation, a test sample was designed to simulate composite bonded porcelain-to-porcelain. A total of 120 samples was prepared and the shear bond strengths were tested. Three composite resins, two porcelain combinations, and two storage-time intervals were used. Significant differences were found among the three types of composite resins. Porcelain combinations did not affect the results. Furthermore, the mean bond strength was higher at 45-day storage than at 90 days.

Analysis of Variance↗
PubMed1995

[The shearing strength of titanium brackets depending on the coating procedure].

It has long been recognized that corrosion of the metal alloys used in the different fields of dentistry can cause intra-oral problems such as allergic reactions. Titanium, a metal all but impervious to corrosion, presents an alternative to the metal alloys used in the fabrication of orthodontic brackets. The purpose of this study was to test the bonding strength between titanium brackets treated with 5 different opaque and non-opaque coatings and a 2-phase adhesive. Five coating methods were tested: N1 (Dentaurum), N2 (Dentaurum), Rocatec (Espe), Sebond (Schütze), Silicoater Standard (Kulzer). After bonding the brackets with a mix adhesive, they were thermocycled and then the shear bonding strength established. Silicoated titanium bracket bases showed clinically acceptable bonding values with the exception of those coated with Sebond without opaquer layer. While the silicoating methods N1, N2, and Rocatec demonstrated minimum bonding strength using the opaquer Visio-Gem, the bonding strength of the bracket bases coated with Sebond MKV, Silicoater Standard and the opaquer appropriate to each was significant increased. Among all the coated surfaces, methods N1, N2, and Rocatec appear to establish the optimum bonding strength values. In addition, the thin opaquer layer (Visio-Gem) used together with these methods offers a good surface adaptation of the bracket to the tooth surface.

Dental Bonding↗
PubMedDate not supplied

The effects of barium sulfate on the polymerization temperature and shear strength of surgical simplex P.

Barium sulfate additive, in amounts ranging from 5% to 60%, causes a progressive reduction in polymerization temperature of the cement without appreciably altering the polymerization time. Concurrently, the mechanical strength of the cement, as determined in shear, decreases with increasing concentration of barium additive. Although inclusion of barium sulfate in acrylic bone cement is primarily used for radiographic contrast purposes, its possible effects on release of monomer and other local mechanisms seem not to have been measured.

Barium Sulfate↗
PubMed1994

Shear strength of ceramic brackets bonded to porcelain.

The purpose of this study was to compare the bond strengths of three different adhesive systems when used alone and combined with a porcelain priming agent to bond ceramic brackets to porcelain surfaces. Sixty porcelain specimens were randomly assigned to the six different treatment groups. Half were bonded with the porcelain priming agent and one of the adhesive systems and the other half with one of the adhesive systems alone. The shear bond strengths of all specimens were tested, with an Instron testing machine, 10 minutes after being bonded. The surface of the porcelain and the bracket base were examined, with scanning electron microscopy (SEM) and qualitative energy dispersive x-ray analysis (EDS), to determine the bond failure patterns and to check the porcelain surface for the presence of cracks and fractures. There was a statistically significant difference within each adhesive between those samples with the priming agent and those without the priming agent. Differences between the three adhesives were not statistically significant (p < or = 0.05).

Acid Etching, Dental↗
PubMed2001

Shear strengths of a gallium alloy bonded to human enamel following nine different surface treatments.

OBJECTIVE: Gallium and indium-containing alloys have demonstrated an ability to wet and bond to many types of materials including enamel. The purpose of this study was to evaluate and compare the bond strengths of a gallium-and-indium-containing alloy and a dental amalgam to human enamel surfaces. METHOD: A flat enamel bonding surface was created by slicing recently extracted human molars with a 180-grit diamond wheel. Cylinders of amalgam or a gallium-indium alloy were bonded to the as-cut surfaces or to as-cut surfaces that had been pumiced, air-abraded or acid-etched for various times. Before testing, samples were stored under different conditions (100% humidity, immersed in water, thermocycled). The shear-bond strength was determined using a crosshead speed of 0.1 mm x min(-1). Sample size was 10. Data was subjected to ANOVA and a post-hoc Tukey's test. RESULTS: The bond strength of amalgam to enamel was zero. The bond strength of the gallium-indium alloy ranged between 6.5 MPa (10s etch with 10% phosphoric acid) and 4.2 MPa (pumiced enamel). Acid-etching significantly increased the bond strength (P>0.0001) The bond strength was not significantly affected by the type of mechanical surface preparation, storage conditions, thermocycling, etching times or acid concentrations. SIGNIFICANCE: Bonding, particularly chemical bonding, suggests a greater potential for better wetting and therefore better sealing of a cavity. Since microleakage of restorations is one of the principal causes of restoration failure, materials that can bond may in turn posses enhanced resistance to microleakage and ultimately, resistance to restoration failure. The gallium-indium alloy evaluated in this study may be such an alloy.

Acid Etching, Dental↗