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PubMed2004

Effects of blood contamination on the shear bond strengths of conventional and hydrophilic primers.

The purpose of this study was to assess the effect of blood contamination on the shear bond strength and failure site of 2 orthodontic primers (Transbond XT and Transbond MIP; 3M/Unitek, Monrovia, Calif) when used with adhesive-precoated brackets (APC II brackets; 3M/Unitek). One hundred twenty bovine permanent mandibular incisors were randomly divided into 8 groups; each group contained 15 specimens. Each primer-adhesive combination was tested under a different enamel surface condition: dry, blood contamination before priming, blood contamination after priming, or blood contamination before and after priming. Stainless steel APC II brackets were bonded to the teeth. After bonding, all samples were stored in distilled water at room temperature for 24 hours and subsequently tested for shear bond strength. Noncontaminated enamel surfaces had the highest bond strengths for both conventional and hydrophilic primers; their values were almost the same. Under blood-contaminated conditions, both primers showed significantly lower shear bond strengths. For each type of primer, no significant differences were reported among the blood-contaminated groups. Significant differences in debond locations were found among the groups bonded with the 2 primers under the various enamel surface conditions. Blood contamination of enamel during the bonding procedure of conventional and hydrophilic primers significantly lowers their bond strength values and might produce a bond strength that is not clinically adequate.

Adhesives↗
PubMed2005

Effect of argon laser curing on the shear bond strength of metal brackets bonded with light-cured glass ionomer cement.

INTRODUCTION: The purpose of this study was to evaluate the shear bond strength and debonding characteristics of glass ionomer cement cured with an argon laser. METHODS: Thirty extracted first premolars were divided into 2 groups of 15. The teeth were cleaned and mounted in resin, and metal brackets were bonded with glass ionomer cement. In the control group, the bond was cured with a halogen light for 40 seconds (20 seconds mesial and 20 seconds distal). In the test group, the specimens were cured with an argon laser for 5 seconds. Brackets were debonded in shear; bond strength was measured, and the adhesive remnant index was scored. RESULTS: The difference in mean shear bond strength was not statistically significant between groups when compared with a t test. More adhesive remained on the enamel surface in the laser group than in the control group. CONCLUSIONS: Argon laser curing produces bond strengths equivalent to those obtained with traditional light curing in much less time, but it leaves more adhesive on the tooth surface.

Adhesiveness↗
PubMed1996

The effect of etch time and debond interval upon the shear bond strength of metallic orthodontic brackets.

Groups of orthodontic brackets were attached to enamel after etching for 15, 30 or 60 seconds. They were debonded by shear forces after 5 or 15 minutes, or 24 hours. The 15 seconds etch/5 minutes debond time specimens had much lower shear strengths than other groups. Sixty-second specimens showed evidence of tooth surface damage after debonding. Fifteen seconds of etching is therefore recommended routinely for bonding brackets. If a bracket is to be ligated within 5 minutes of placement, 30 seconds etching is recommended. A 60-second etch is considered too severe and should not be used.

Acid Etching, Dental↗
PubMed1993

Effect of the tooth microstructure on the shear bond strength of a dental composite.

Plane human enamel and dentin surfaces were used for microstructural investigation and shear bond testing. The dental tissue microstructure was characterized through the surface topology, the concentration in mineral elements (determined by electron microprobe analysis), and the Vickers microhardness for the same dental tissue. The etched prismatic enamel presents a surface roughness of about 200% of the apparent area, while the intertubular surface fraction of the dentin is, on the average, equal to 75%. The calcium concentration lies between 23.2 and 37.8% of the enamel total mineral content, and 18.5 and 28.2% of the dentin. The microhardness varies from 205 to 378 Hv for the enamel and from 37 to 98 Hv for the dentin. Also, the shear bond strength to a chemosetting adhesive/composite system varies from 10.4 to 23.9 MPa for the enamel and from 0.0 to 5.0 MPa for the dentin. It is shown that the shear bond strength is strongly correlated to the microhardness through a simple linear equation valid for both enamel and dentin surfaces. In turn, the microhardness is correlated to the calcium concentration through two distinct linear relations. These correlations lead to the intrinsic dependence of the shear bond strength on the calcium concentration of the dental tissue, providing that corrections are applied to the bond strength data in order to take into consideration the effective solid area of the adherend and the polymerization retraction stress. Consequently, it is proposed that the adhesion mechanisms for the both enamel and the dentin are controlled, to a major extent, by the mineral content and the surface topology of the tooth.

Calcium↗
PubMed1997

Effects of adhesive primers for noble metals on shear bond strengths of resin cements.

OBJECTIVES: The purpose of this study was to evaluate the durability and shear bond strengths of the different combinations of two adhesive primers and three resin cements to two types of noble metal alloys, silver-palladium copper-gold and type IV gold alloys. METHODS: The adhesive luting agents Imperva Dual, Panavia 21 and Super-Bond C&B, and the adhesive primers Metal Primer and V-Primer were used. Two sizes of casting alloy disks were nonprimed or primed and cemented with each adhesive luting agent. The specimens were stored in 37 degrees C water for one day and then immersed alternately in 4 degrees C and 60 degrees C water baths for 1 min each for up to 100,000 thermal cycles before shear mode testing at a cross-head speed of 0.5 mm/min. RESULTS: The application of Metal Primer was effective for improving the shear bond strengths between each of the three resin cements and both noble metal alloys compared with nonprimed specimens. When each noble metal alloy was cemented with Super-Bond C&B, there were no significant differences between the bond strengths with the use of Metal Primer and those with the use of V-Primer at 100,000 thermal cycles. However, V-Primer was ineffective for enhancing the shear bond strengths of Imperva Dual and Panavia 21 to noble metals. CONCLUSION: Metal Primer and V-Primer are clinically useful for strongly bonding adhesive resin cements to noble metal alloys.

Analysis of Variance↗
PubMed2001

Effect of three adhesive primers for a noble metal on the shear bond strengths of three resin cements.

The purpose of this study was to evaluate the durability and shear bond strengths of the different combinations of three adhesive primers and three resin cements to a silver-palladium-copper-gold (Ag-Pd-Cu-Au) alloy. The adhesive primers Alloy Primer (AP), Metal PrimerII (MPII) and Metaltite (MT), and the resin cements BistiteII (BRII), Panavia Fluoro Cement (PFC) and Super-Bond C&B (SB) were used. Two sizes of casting alloy disks were either non-primed or primed and cemented with each of the three resin cements. The specimens were stored in a 37 degrees C water bath for 24 h and then immersed alternately in 4 and 60 degrees C water baths for 1 min each for up to 100,000 thermal cycles. Shear mode testing at a crosshead speed of 0.5 mm/min was then performed. The application of MPII or MT was effective for improving the shear bond strength between each of the three resin cements and the Ag-Pd-Cu-Au alloy compared with non-primed specimens. However, when primed with MPII or MT and cemented with SB, the bond strength at 100,000 thermal cycles was significantly lower than that at thermal cycle 0. When primed with AP, the specimens cemented with BRII or PFC showed lower bond strength than non-primed specimens and failed at the metal-resin cement interface at 100,000 thermal cycles. On the other hand, AP was effective in enhancing the shear bond strength of SB to the Ag-Pd-Cu-Au alloy. The five combined uses of an adhesive metal primer and resin cement (combinations of MPII or MT and BRII or PFC and AP and SB) are applicable to the cementation of prosthodontic restorations without complicated surface modification of the noble alloy.

Adhesives↗
PubMed1998

Mechanical properties and strength retention of carbon fibre-reinforced liquid crystalline polymer (LCP/CF) composite: an experimental study on rabbits.

A novel composite material with ultra-high flexural strength and cortical-bone-matched elastic modulus made of liquid crystalline polymer reinforced with carbon fibres (LCP/CF) is described. Cylindrical rods of 3.2 mm diameter and 50 mm length were fabricated by a preimpregnation/pultrusion method. The initial mechanical properties of the LCP/CF rods were as follows: flexural strength 448 MPa, flexural modulus 43 GPa, shear strength 164 MPa, and interlaminar shear strength 15.3 MPa. In the in vitro study the LCP/CF rods were immersed in phosphate-buffered saline of 37 degrees C for 12, 24, and 52 weeks. In the in vivo study the LCP/CF rods were implanted into the medullary cavity of both femora and subcutaneous tissue of the New Zealand White rabbits for 12, 24, and 52 weeks. The flexural strength of the LCP/CF rods at 52 weeks was 463 MPa in saline, 467 MPa in the subcutaneous tissue and 466 MPa in the medullary cavity of the femur. The flexural modulus was 44.6, 48.9 and 46.2 GPa, respectively. The corresponding shear strength values were 160, 178 and 181 MPa. We conclude that the LCP/CF is a promising material for high-load applications and the LCP/CF rods retain their initial mechanical properties in one-year follow-up in vivo and in vitro.

Animals↗
PubMed2006

Effect of an antioxidizing agent on the shear bond strength of brackets bonded to bleached human enamel.

INTRODUCTION: The purpose of this study was to investigate the effect of antioxidant treatment and delayed bonding on the shear bond strength of metal brackets bonded with composite resin to human enamel after bleaching with carbamide peroxide (CP). METHODS: Eighty recently extracted premolars were divided into an experimental group (n = 60), which was bleached with 10% CP, and a control group (n = 20), which was not bleached. The experimental group was further divided into 3 groups. Specimens in group 1 (n = 20) were bonded immediately after bleaching; specimens in group 2 (n = 20) were bleached, then treated with 10% sodium ascorbate, an antioxidant agent, and then bonded; group 3 specimens (n = 20) were bleached, then immersed in artificial saliva and held for 1 week before bonding. The specimens were debonded, and the enamel surfaces and bracket bases were examined with a stereomicroscope. The adhesive remnant index was used to assess the amount of resin left on the enamel surfaces after debonding. The shear bond strength data were subjected to 1-way analysis of variance. Multiple comparisons were performed with the Bonferroni test. The level of significance was established at P < .05 for all statistical tests. RESULTS: Shear bond strength of brackets bonded immediately after bleaching with 10% CP was significantly lower than that of brackets bonded to unbleached enamel (P < .05). No statistically significant differences in shear bond strength were noted when the antioxidant-treated and delayed bonding groups were compared with the control group (P > .05). CONCLUSIONS: Bleaching with 10% CP immediately before bonding reduces the bond strength of composite resin to enamel. Treating the bleached enamel surface with 10% sodium ascorbate or waiting 1 week reverses the reduction.

Adhesives↗
PubMed2004

[Effect of fluorided etching fluid on the shear bond strength and the deposition on the surface of enamel.].

PURPOSE: The aim of this study was to find the best concentration of fluorided etching acid in the dental clinic which had both the best shear bond strength and the maximal anti-caries effect. METHODS: 84 extracted human premolars were divided into four groups of 21 teeth each. The enamel of each group was conditioned with 35% phosphoric acid containing 0%, 1.23%, 2%, 3% NaF. The shear bond strength was tested by bond strength machine and the enamel morphology was observed by scanning electron microscopy at once, 1 week, 4 weeks, 12 weeks, 24 weeks after etching. The shear bond strength was statistically analyzed by SPSS10.0 software. RESULTS: The shear bond strength of the group whose acid containing 3% NaF was less than the others significantly (P<0.05); and there was no significant difference among the other groups (P>0.05). The amount of the deposition on the surface of enamel after etching was increased with the time after etching and the concentration of NaF increasing. CONCLUSIONS: 2% NaF added to 35% phosphoric acid has both the best bond strength and the best effect of preventing enamel from caries.

Acid Etching, Dental↗
PubMed1993

Shear bond strength and microleakage of All-Bond.

The shear bond strengths (SBS) were determined to enamel etched with Uni-Etch (Procedure A) or treated with the mixed Primer A and B (Procedure B), to dentin treated with the Dentin Conditioner (Procedure C) or etched with All-Etch (Procedure D), to amalgam treated with the mixed Dual Opaquer Base and Catalyst which was allowed to self cure (Procedure E) or light cured (Procedure F), of amalgam to dentin (Procedure G), to cast metal alloy (Procedure H), and to porcelain (Procedure I). The test specimens were stored in physiological saline at 37 degrees C for 24 hours, and the SBS determined by the application of a shear load directed at the base of the bonded composite cylinders at a crosshead speed of 0.5 mm/minute. The SBS were calculated and expressed in MPa. Standardized Class V preparations were made at the facial aspects of the roots of the teeth, treated with the Dentin Conditioner (Procedure J) or etched with All-Etch (Procedure K). Quantitative microleakage (QM) was determined by means of a spectrophotometric dye-recovery method and expressed in microgram dye/restoration. The mean +/- SD of the SBS in MPa were: A: 18.3 +/- 2.1; B: 22.0 +/- 2.9; C: 17.2 +/- 3.6; D: 15.6 +/- 3.7; E: 12.9 +/- 1.9; F: 13.6 +/- 2.0; G: 13.0 +/- 3.5; H: 21.8 +/- 2.6; I: 8.2 +/- 2.8. The mean +/- SD of the QM in microgram dye/restoration were: J: 2.61 +/- 1.22 and K: 1.95 +/- 0.59. The analysis of the SBS data showed that the application of the Primer to enamel resulted in a significant increase in SBS.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1991

Effect of a fluoridated etching gel on enamel morphology and shear bond strength of orthodontic brackets.

The purpose of this study was to compare the enamel morphology and shear bond strengths of orthodontic brackets bonded to enamel etched with a fluoridated or a nonfluoridated phosphoric acid gel. Ten extracted third molars were used for the enamel morphology evaluation. The buccal surfaces were divided in two sections separated by an occlusogingival groove. One side was etched for 60 seconds with a 38% phosphoric acid gel, and the other side was etched with a 60% phosphoric acid gel containing 0.5% sodium fluoride. The specimens were then examined with a scanning electron microscope. For the shear bond strength tests, 30 extracted third molars were used. The buccal enamel surfaces of the mesial cusp were used, and the teeth were randomly divided into two groups of 15 teeth each--group 1, 38% phosphoric acid gel for 60 seconds; group 2, 60% phosphoric acid gel with 0.5% sodium fluoride for 60 seconds. Orthodontic lingual buttons were bonded to the etched surfaces with a composite resin. The results showed that the overall morphologic etching effect was similar in both groups. The mean shear bond strength for group 1 was 11.8 MPa +/- 4.2, and for group 2 it was 16.5 MPa +/- 5.1. This difference was statistically significant (p less than 0.01).

Acid Etching, Dental↗
PubMed2002

Polymerization with a micro-xenon light of a resin-modified glass ionomer: a shear bond strength study 15 minutes after bonding.

The purpose of this study was to evaluate the initial shear bond strength (15 minutes after bonding) of a resin-modified glass ionomer (RMGIC, Fuji Ortho LC) cured with two different light-curing units: a conventional visible light (Ortholux XT) and a microxenon light (Aurys). Seventy-five freshly extracted bovine permanent mandibular incisors were randomly assigned to one of five groups; each group consisted of 15 specimens. Group A (Transbond XT) and group B (Fuji Ortho LC) were exposed to the visible light for 20 and 40 seconds, respectively, and used as controls. The remaining three groups (C, D, and E) were bonded with Fuji Ortho LC and cured with Aurys for 10, 5, and 2 seconds, respectively. All samples were tested in a shear mode on an Instron universal testing machine 15 minutes after bonding. The shear bond strength of the control group bonded with Transbond XT was significantly higher (P = 0.000) than those of all the other groups tested. Regarding Fuji Ortho LC, no statistically significant differences were found between the bond strength of the control group cured with Ortholux XT, and those of the groups cured with Aurys for 2, 5, and 10 seconds. The present findings indicate that, compared with visible light-curing, the micro-xenon light enables the clinician to significantly reduce the curing time of RMGICs, without affecting their initial shear bond strengths.

Acid Etching, Dental↗
PubMed1997

Effects of a self-etching primer on enamel shear bond strengths and SEM morphology.

PURPOSE: To study a dental adhesive system containing a self-etching primer, by evaluating the enamel shear bond strengths and comparing the SEM interfacial morphology. MATERIALS AND METHODS: 100 flat enamel bonding sites were prepared to 600-grit on proximal surfaces of caries-free human molars. The bonding surfaces were treated with Clearfil Liner Bond 2 as recommended by the manufacturer, or combined with various acidic etchants. A composite rod (Clearfil Photo Anterior) was applied to the bonding area in two increments in a Teflon mold and polymerized for 100 s. After 24 h of water storage, the specimens were thermocycled and the shear bond strengths measured using an Instron testing machine. Forty extra molar crowns were roughened and treated with Clearfil Liner Bond 2 and alternative etchants, as described. A low-viscosity resin was bonded to the occlusal surfaces of these crowns, which were further demineralized and deproteinized. Field-Emission SEM examinations were carried out to evaluate the effects of different treatments on enamel surfaces. RESULTS: The mean shear bond strengths were in the range of 18.1 MPa to 25.9 MPa, without significant differences between pairs of means. The failures were predominantly of the adhesive type. The use of alternative etchants resulted in the deepest etching patterns. The use of Clearfil Liner Bond 2, according to manufacturer's directions, resulted in a poorly-defined etching pattern. Regardless of the alternative etchant used, the use of the self-etching primer did not affect the mean enamel shear bond strength.

Acid Etching, Dental↗
PubMed1994

Shear bond strengths of a glass ionomer for direct bonding in orthodontics.

This study was undertaken to compare the shear bond strengths of mesh-backed orthodontic buttons bonded to human enamel using a glass ionomer marketed for direct bonding in orthodontics, both in conjunction with, as well as without, enamel etching and to compare the results with a no-mix composite bonding resin. Freshly extracted noncarious human premolar crowns were used, to which mesh-backed metal orthodontic buttons were bonded to the lingual surfaces with one of three methods: group 1, glass ionomer without enamel etching; group 2, glass ionomer with enamel etching; and group 3, with a no-mix orthodontic bonding resin with enamel etching. After being stored in water for 48 hours at 37 degrees C, the samples were tested to failure in an Instron with the Bencor testing system. The data were statistically analyzed with the Mann-Whitney U test. The debonded specimens were visually inspected in respect of failure mode. The no-mix bonding resin had a significantly higher shear bond strength than the glass ionomer cement. Enamel etching with 37% orthophosphoric acid increased the mean shear bond strength of the glass ionomer, however, not significantly. Less cement remained on enamel after debonding when the glass ionomer was used when compared with residual resin when the no-mix bonding resin was used. Clinical research by several investigators is advised to determine the bond failure rate of glass ionomers when used in conjunction with orthodontic bracket bonding.

Acid Etching, Dental↗
PubMed1994

Effect of surface treatments of porcelain on the shear bond strength of applied dual-cured cement.

The effect of different surface treatments of porcelain on the shear bond strength of the applied dual-cured cement was examined. Acid etching with hydrofluoric acid, roughening the porcelain surface by means of grinding with a diamond bur, and the use of silane coupling agent alone and with combinations of these surface treatments were used. Silane treatment resulted in a shear bond strength on roughened porcelain surfaces that was statistically significantly greater than all other treatment groups (p < 0.05). However the use of two mechanical bond systems together with a chemical bond did not improve the shear bond strength.

Analysis of Variance↗
PubMedDate not supplied

Shear bond strength of direct composite repairs in indirect composite systems.

Indirect composite restorations may require repair during clinical service. This study evaluated the shear bond strength of direct composite repairs in indirect composites after four surface treatment procedures. Cylinders of three indirect composites (n = 10 per group) received the following surface treatment: sandpaper finishing (control group), 50 microm aluminum oxide sandblasting, 50 microm aluminum oxide sandblasting (plus 10% fluoridric acid etching), and 30 microm silaned silicon sandblasting. Repair procedure was simulated with the application of an adhesive agent and packing of a direct composite. After storage for one hour in relative humidity and 23 hours in distilled water at 37 degrees C, the specimens were tested for shear bond strength using a universal testing machine at a crosshead speed of 0.5 mm/min. Groups treated with aluminum oxide sandblasting or CoJet Sand had the highest mean values of shear bond strength with no statistically significant difference between the two techniques.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1989

Effects of phosphoric acid concentration and etch duration on the shear bond strength of an orthodontic bonding resin to enamel. An in vitro study.

The purpose of this in vitro study was to determine the effects of phosphoric acid (H3PO4) concentration and duration of etching on the shear bond strength of an orthodontic bonding resin to enamel. Nine bonding procedures, each involving 18 extracted human maxillary permanent canines, were used. Ground enamel surfaces were etched with a 37% H3PO4 solution, a 15% H3PO4 gel, or a 5% H3PO4 solution for 60, 30, and 15 seconds, respectively. Cylinders of an orthodontic bonding resin, Concise, were prepared in a special device. The test specimens were disassembled 15 minutes after preparation and stored in distilled water at 37 degrees C for 24 hours. A shear load was applied to the bonded cylinders at a crosshead speed of 0.02 in.min-1 in an Instron testing machine, and the shear bond strengths were calculated and expressed in MN.m-2. A two-factor analysis of the data showed that the H3PO4 concentration had no significant effect on the shear bond strength, but the duration of etching affected shear bond strength significantly. The enamel aspects of the fractured test specimens were examined microscopically and the percent failure within the bonding resin at the bonding sites estimated. The correlation between shear bond strength and percentage failure within the bonding resin was not significant. The effects of the nine etching procedures on ground and unground enamel surfaces were studied by scanning electron microscopy. The etching procedures produced well-defined etching patterns on both ground and unground enamel surfaces.

Acid Etching, Dental↗
PubMed2003

Effect of fluorosis on dentine shear bond strength of a self-etching bonding system.

The purpose of this study was to investigate the effect of dental fluorosis on shear bond strength of a composite material to dentine. Forty human premolar teeth were classified according to the severity of fluorosis using the Thylstrup and Fejerskov index and were divided into four groups (TFI scores of 0, 3, 4 and 5) of 10 teeth. Non-fluorosed teeth (TFI score of 0) served as the control group. A self-etching light-cured bonding system, Clearfil SE Bond, and a micro-hybrid light-cured composite, Clearfil AP-X were selected for the study. Buccal surfaces of mounted teeth were ground flat to expose the dentine. Composite cylinders, 4 mm diameter and 4 mm length, were bonded to the treated dentine surfaces. Shear bond strength was measured with an universal testing machine at a cross-head speed of 0.5 mm min-1. After failure, the fracture surfaces were examined under a stereo microscope. The mean bond strength was 24.37 +/- 3.54 MPa for non-fluorosed teeth and varied between 22.72 +/- 3.52 and 27.02 +/- 5.91 MPa for fluorosed teeth. The difference between the mean values for bond strength was not statistically significant (P > 0.05). Adhesive mode of failure was most prevalent in non-fluorosed teeth. It can be concluded that fluorosis does not affect the shear bond strength of composite material to human dentine.

Adhesiveness↗