Significant Differences In Bond Strength Research Articles

In vitro effect of nanoleakage expression on resin-dentin bond strengths analyzed by microtensile bond test, SEM/EDX and TEM

This study evaluated the effect of multiple consecutive adhesive resin coatings of adhesive bonded to human dentin on nanoleakage and resin–dentin bond strength. Resin bonded dentin specimens were prepared using a total-etch adhesive (One-Step Plus) applied as multiple consecutive coating, or using two self-etch adhesive systems (iBond or Fluoro Bond). For the total-etch adhesive, resin application and air evaporation were performed 1, 2, 3, or 4 times. The self-etch adhesives were applied according to manufacturers’ instructions. Resin–dentin bonded beams were prepared and immersed in water (control) or ammoniacal silver nitrate. After storage, microtensile bond strengths were measured. The fractured surfaces were examined by scanning and transmission electron microscopy (SEM and TEM), and energy-dispersive X-ray spectrometry (EDX). No significant differences in bond strength were found between water and silver nitrate storage groups. Several types of silver depositions (spotted, reticular, or water trees) were found in adhesive joints. The bond strengths of the single coated specimens of the total-etch adhesive were significantly lower than those receiving 2–4 coatings. Single coats produced more nanoleakage than multiple coats. However, no correlation was found between the bond strengths and nanoleakage between the different adhesives (total-etch adhesive with different conditions or self-etch adhesives).

Effect of drying time of 3-methacryloxypropyltrimethoxysilane on the shear bond strength of a composite resin to silica-coated base/noble alloys

Objectives. In this in vitro study, the effect of various drying (surface reaction) times of a commercial silane, other than that recommended by the manufacturer (at least 5 min), on the bond strength between the resin composite and silica coated base and noble alloys was evaluated. Methods. A total of 112 disc specimens (9 mm diameter and 0.5 mm thickness) were cast out of two types of alloy designed for ceramic firing, one of which was a noble (Degunorm) (gold–silver–platinum) and the other a base alloy (Wiron 99) (nickel–chromium–molybdenum). The specimens were assigned to two main groups according to each alloy type. These two main groups were further divided into seven subgroups, having eight specimens each. The specimens of both alloy types were air-abraded with 30 μm silica (SiO 2) coated alumina (Al 2O 3) (CoJet ®-Sand, ESPE, Seefeld, Germany). The conditioned surfaces were coated with 3-methacryloxypropyltrimethoxysilane (MPS) and were allowed to react and dry for 1, 2, 3, 4, 5, 6, and 7 min, respectively, before the opaquer was applied. Immediately after the waiting periods for the silane to dry, first opaquer and then resin composite were applied. After storage in water for 30 days at 37 °C and thermocycling (5000 cycles, 5–55 °C), shear tests were performed using the universal testing machine at a crosshead speed of 0.5 mm/min. Results. Analysis of data showed no significant difference in bond strength for any silane drying and reaction period for both base and noble alloys between 1 and 7 min (ANOVA, P=0.05) (Degunorm: 5.8–7.4 MPa and Wiron 99: 7.2–10.2 MPa, respectively). Bond strengths of resin composite to base alloys were significantly higher than those to noble alloys at 2, 3 and 5 min ( P=0.0045, P=0.05, P=0.002, respectively). Significance. In order to optimize the flow of laboratory work, the silane solution drying time might be reduced to 1 min for both base and noble alloys.

The effect of thermal cycling on the bond strength of low-fusing porcelain to commercially pure titanium and titanium–aluminium–vanadium alloy

Objectives. Titanium-ceramic restorations are currently used in spite of the pending problem of titanium-ceramic bonding, which has only been partially solved. In addition, some titanium-ceramic systems appear to be susceptible to thermal cycling, which can cause weaker bond strength. The objective of this study was to evaluate the bonding characteristics of titanium porcelain bonded to commercially pure titanium (Ti-Cp) or titanium–aluminum–vanadium (Ti–6Al–4V) alloy as well as the effect of thermal cycling on bond strength. Methods. A three-point-flexure-test was used to evaluate the bond strength of titanium porcelain bonded to commercially pure titanium and Ti–6Al–4V alloy according to DIN 13.927. To evaluate the effect of thermal cycling on the samples, half were thermal cycled in temperatures ranging from 4 °C (±2 °C) to 55 °C (±2 °C). Results were compared with palladium-silver (Pd–Ag) alloy bonded to conventional porcelain (control). Scanning electron microscope (SEM) photomicrographs were taken to characterize the failed surfaces in the metal–ceramic interface. Anova and Tukey's multiple comparison tests were used to analyze the data at a 5% probability level. Results. Thermal cycling did not significantly weaken the bond strength of porcelain to titanium interfaces. There was no significant difference in bond strength between commercially pure titanium (23.60 MPa for thermal cycled group and 24.99 MPa for non-thermal cycled group) and Ti–6Al–4V groups (24.98 and 25.60 MPa for thermal cycled and non-thermal cycled groups, respectively). Bond strength values for the control group (47.98 and 45.30 MPa, respectively) were significantly greater than those for commercially pure titanium and Ti–6Al–4V combinations. Significance. The bond strength of low fusing porcelain bonded to cast pure titanium or Ti–6Al–4V alloy was significantly lower than the conventional combination of porcelain–Pd–Ag alloy. Thermal cycling did not affect the bond strength of any group.

Effect of irrigation solutions on dentin bonding agents and restorative shear bond strength

Statement of Problem. The presence of irrigation solution prior to the application of dentin bonding agents may be one source of contamination and may adversely affect bond strength. Purpose. The purpose of this in vitro investigation was to evaluate the effect of irrigation solutions of different purity levels on the shear bond strength of a hybrid composite to dentin. Material and Methods. Forty extracted, intact human molars were hand-scaled. All soft tissue was removed, and the teeth were stored in room-temperature tap water for 1 week. Subsequently, each tooth was embedded in autopolymerizing acrylic resin with the coronal portion exposed. After complete polymerization of the resin, the dentin surfaces were exposed, and the crown was cut longitudinally on all 4 sides to produce flat dentin surfaces for bonding. The prepared specimens were assigned to 4 groups of irrigation solutions: tap water (control), sterile water, 0.9% NaCl irrigation solution, and filtered water. Within each irrigation group were 4 dentin bonding agent subgroups: Prime & Bond NT, One-Step, Single Bond Adhesive, and OptiBond Solo. The dentin surfaces (n = 10 per irrigation/bonding agent pair) were etched with 37% phosphoric acid, rinsed with the assigned irrigation solution for 15 seconds, and then dried. Plastic cylinders (3 mm long × 3 mm inner diameter) were filled with a hybrid composite (Herculite XRV) and bonded to the dentin. Specimens were loaded in a universal testing machine, and shear force was applied to the base of the composite cylinders, parallel to the dentin surfaces, at a crosshead speed of 0.05 in/min until fracture. Failure loads were recorded. Bond strength data were compared with analysis of variance (P<.05). Post-hoc comparisons of means were performed with t tests and P values adjusted for multiple comparisons (Bonferroni method). Results. Tap water irrigation (control) produced no significant difference in bond strengths for all dentin bonding agents tested. When other irrigation solutions were used, One-Step consistently produced significantly lower bond strengths than other dentin bonding agents (P<.05). No preferential choice of irrigation solution could be made for Prime & Bond or Single Bond Adhesive. However, when One-Step or Solo was used, irrigation with normal saline significantly reduced bond strengths (P<.05). Conclusion. Within the limitations of this study, the bond strength to dentin of a hybrid composite irrigated with different solutions was dependent on the dentin bonding agent used. (J Prosthet Dent 2002;87:628-32.)

Effect of enamel pretreatments on bond strength of compomer

Objectives: The objective of this study was to evaluate the effect of various enamel surface treatments on the bond strength of a compomer to enamel. Methods: Ground bovine enamel specimens were divided into four groups. A compomer (F2000, 3M) was bonded to the specimens using different enamel surface treatments. Two groups examined the effect of application of the F2000 self-etching primer/adhesive (3M) with respect to static or dynamic priming. A third examined use of the primer/adhesive after phosphoric acid etching, and the fourth (control) group provided bond strength of the compomer to phosphoric acid etched enamel with a resin bonding system (Single Bond, 3M). Shear bond strengths for the specimens were measured after 24 h storage in water at 37°C. Effects of the various surface treatments on enamel were examined by SEM. Results: Significant differences in bond strength of compomer to enamel were found that were related to the various surface pretreatments. Dynamic priming resulted in higher enamel bond strengths than static priming, and the best bond strengths were obtained when the enamel was etched with phosphoric acid. SEM analysis showed that depth of etch and resin penetration was also directly related to the bond strengths measured. Significance: Bond strength of compomer to enamel is significantly affected by the method of pretreatment of the enamel.

Bond strength of binary titanium alloys to porcelain

The purpose of this study was to investigate the bond strength between porcelain and experimental cast titanium alloys. Eleven binary titanium alloys were examined: Ti–Cr (15, 20, 25 wt%), Ti–Pd (15, 20, 25 wt%), Ti–Ag (10, 15, 20 wt%), and Ti–Cu (5, 10 wt%). As controls, the bond strengths for commercially pure titanium (KS-50, Kobelco, Japan) and a high noble gold alloy (KIK, Ishifuku, Japan) were also examined. Castings were made using a centrifugal casting unit (Ticast Super R, Selec Co., Japan). Commercial porcelain for titanium (TITAN, Noritake, Japan) was applied to cast specimens. The bond strengths were evaluated using a three-point bend test according to ISO 9693 . Since the elastic modulus value is needed to evaluate the bond strength, the modulus was measured for each alloy using a three-point bend test. Results were analyzed using one-way ANOVA/S-N–K test ( α=0.05). Although the elastic moduli of the Ti–Pd alloys were significantly lower than those of other alloys ( p=0.0001), there was a significant difference in bond strength only between the Ti–25Pd and Ti–15Ag alloys ( p=0.009). The strengths determined for all the experimental alloys ranged from 29.4 to 37.2 MPa, which are above the minimum value required by the ISO specification (25 MPa).

Effects of two silane coupling agents, a bonding agent, and thermal cycling on the bond strength of a CAD/CAM composite material cemented with two resin luting agents

Statement of problem. Surface treatment of CAD/CAM-generated composite material is important for a strong bond of resin luting agents to composite material. Purpose. This study evaluated the shear bond strengths of 2 dual-cured resin luting agents to a CAD/CAM composite material and the effect of silane coupling agent and bonding resin on the bond strength. Material and methods. Rectangular- and disk-shaped CAD/CAM composite materials were untreated or treated with 1 of the 2 silane coupling agents or bonding resin and then cemented together with 1 of the 2 dual-cured resin luting agents. Half of the specimens were stored in water at 37°C for 24 hours, the other half thermocycled 50,000 times before shear bond strength testing. Shear bond strengths were measured with a servohydraulic mechanical testing machine, and results were analyzed with 2-way analysis of variance. Results. Surface treatment by silane coupling agent improved the shear bond strength when compared with nontreatment. Specimens treated with bonding resin showed significantly greater shear bond strength than the untreated groups. However, all specimens had the same adhesive failures at the composite-luting agent interface as untreated groups. When the CAD/CAM composite material was treated with 1 of the 2 silane coupling agents, no significant differences in bond strength were noted between water storage alone and after 50,000 thermocycles. For the 2 groups treated with bonding resin or silane coupling agent and cemented with 1 of the 2 dual-cured resin luting agents, there were significant increases in bond strength after 50,000 thermocycles, compared with specimens that were not subjected to thermal cycling. On the other hand, for the 2 untreated groups, there were significant decreases in bond strength after thermocycling. After 50,000 thermocycles, all specimens treated with silane coupling agent and then cemented with 1 of the 2 resin luting agents showed cohesive failures within the composite material. Conclusion. The application of a silane coupling agent to the CAD/CAM composite surface provided the highest bond strength between the resin luting agent and composite after long-term thermal cycling. (J Prosthet Dent 2001;85:184-9.)

Effects of aging on repair of resin‐modified glass–ionomer cements

The effects of aging on the repair bond strengths of resin-modified glass-ionomer cements after different methods of surface conditioning were studied. Surface conditioning methods included the following: maleic acid; maleic acid with resin application; polyacrylic acid; polyacrylic acid with resin application. Shear bond testing between the aged and new material was carried out with an Instron Universal testing machine. Surface conditioning with maleic acid and resin application gave the highest repair bond strengths at 3 and 6 months. There was, however, no statistically significant difference in bond strengths between the different treatment groups after both 3 and 6 months storage. Intergroup comparisons revealed no significant difference in failure modes after both storage periods. For all treatment groups, no significant difference in repair bond strengths was noted between storage after 1 week, 3 and 6 months. There appears to be a general decrease in repair bond strengths for all treatment groups after 3 months storage. The clinical repair of resin-modified glass-ionomer cements after this period of time is therefore not recommended.

Monkey pulpal response and microtensile bond strength beneath a one-application resin bonding system in vivo

Objectives: The aim of this in vivo study was to investigate the biocompatibility and microtensile bond strength of a one-application resin bonding system. Methods: Class V cavities were prepared on the facial surfaces of 36 intact monkey teeth, and the cavities were restored with an experimental one-application resin bonding system (TOF-1; Tokuyama Corp., Tokuyama, Japan) and a hybrid resin composite (PALFIQUE ESTELITE; Tokuyama Corp., Tokuyama, Japan). Histopathological changes of the restored teeth were evaluated at 3, 30 and 90 days after operation ( N=10). Microtensile bond tests were performed at 3 and 90 days after operation ( N=10). Results: Only two of 30 pulps showed a slight inflammatory cell infiltration. There were no statistically significant differences in the incidence of slight inflammatory cell infiltration among time periods. Bacterial penetration along the cavity walls could not be detected in any specimen. The mean microtensile bond strength at 3 days after operation was 20.6 MPa, and that at 90 days was 14.9 MPa. Differences in bond strengths between the 3 day specimen and the 90 day specimen were statistically significant ( p<0.05). Conclusions: The one-application resin bonding system exhibited acceptable biologic compatibility to the monkey pulp. Although there were statistically significant differences in bond strengths between the 3 day specimen and the 90 day specimen, this material provided a hermetic seal, eliminating bacterial microleakage.

Morphology and immersion behavior of plasma-sprayed hydroxyapatite/bioactive glass coatings.

A series of hydroxyapatite/bioactive glass (HA/BG) coatings have been plasma-sprayed on Ti6Al-4V substrate using HA/BG powders that were prepared by both sinter-granulation and direct mixing methods. The morphology and immersion behavior of these coatings in a simulated body fluid (SBF) were investigated. The results showed that in-house fabricated BG and sinter-granulated HA powders were irregularly shaped and dense. When 5 wt % or more BG was added in HA, the powder became rough and porous. X-ray diffraction (XRD) patterns showed that the presence of BG enhanced the decomposition of HA structure during fabrication of the powders. Reasonably high bond strengths were obtained from all coatings. The granulated type HA/BG coatings showed no significant differences in bond strength from the mixed type HA/BG coatings. The plasma spray process itself and the presence of BG enhanced the decomposition of apatite. Surface morphology of all sinter-granulated type coatings was similar to that of monolithic HA coating, that was comprised of patches of smooth and shiny glassy film and irregularly-shaped particles on its surface. The dissolution depth of plasma-sprayed coatings immersed in SBF was largely dependent on the type and composition of the coating. Granulated type HA/BG coatings were much less dissolvable than monolithic HA or mixed type HA/BG coatings. It seems that the presently used granulation method for the preparation of HA/BG powders plays a predominant role in determining the dissolution behavior of the plasma-sprayed coatings.

Sealant bond strengths of CO2 laser‐etched versus acid‐etched bovine enamel

Background and Objective The purpose of this study was to evaluate sealant shear bond strength on bovine enamel with standard acid etching compared with CO2 laser etching. Study Design/Materials and Methods Bovine enamel was prepared either by acid or laser etching and divided into four experimental groups, either acid or laser-etched teeth with or without a primer. A gelatin capsule was used to place the sealant on the prepared enamel surface and the bond tested in shear. Also surface roughness was evaluated by using a surface analyzer and an atomic force microscope. Results Shear bond strength results were the following: acid etch = 8.8 ± 3.8 MPa, acid etch with primer = 10.3 ± 5.5 MPa, laser etch = 4.0 ± 1.1 MPa, and laser etch with primer = 6.2 ± 2.3 MPa. Analysis of variance statistical analysis found no significant difference in bond strength between the acid-etched groups. However, the laser-etched groups had significantly lower bond strengths from the acid-etched teeth. In addition, a significant difference was observed between the laser-etched groups, where the use of the primer helped to increase the bond strength of the sealants. The surface roughness was significantly greater on the laser-etched teeth at the μm level (by using a surface analyzer) from the acid-etched and the control specimens. No difference in roughness (by using an atomic force microscope) was observed at the nanometer level between the laser and acid-etched teeth. Conclusion For these particular settings, the laser-etched teeth resulted in lower bond strengths to enamel and the use of a primer increased the bond strength for laser-etched teeth only. Lasers Surg. Med. 27:111–118, 2000. © 2000 Wiley-Liss, Inc.

Tensile bond strength to and SEM evaluation of ground and intact enamel surfaces

Objectives: The aim of this study was to evaluate the bonding of four commercially available adhesive systems to ground and intact enamel surfaces. Methods: Extracted human teeth were used to measure the microtensile bond strength to enamel and a field-emission scanning electron microscopy (FE-SEM) was used to observe the bonded interface and the effect of the surface conditioning of each material. Intact buccal enamel surfaces were cleansed with tooth paste using a rotary dental brush, and the ground enamel surfaces were prepared by reducing approximately 0.5 mm from the buccal enamel surfaces using a high-speed diamond bur. One-Step (OS, Bisco), Single Bond (SB, 3M), Clearfil Liner Bond II (LBII, Kuraray), and Tokuso Mac Bond II (MBII, Tokuso) were evaluated for their ability to bond to enamel. Results: There was no significant difference in bond strengths between the materials when they were applied to ground enamel surfaces ( p>0.05). However, the bond strengths of the self-etching systems, LBII and MBII, had significantly lower bond strengths to intact enamel than the bonding systems OS and SB using phosphoric acid etching ( p<0.05). FE-SEM revealed that the etching pattern of self-etching primers was not deep enough to obtain good penetration of bonding resin when applied to intact enamel surfaces. Conclusions: Phosphoric acid etching produced good resin adhesion to ground and intact enamel. The self-etching/self-priming systems also produced good adhesion to ground enamel, but had lower bond strengths to intact enamel.

Bond strength between cements and metals used for endodontic posts

Objectives. Adhesive cements used with metal endodontic posts may decrease fracture in non-vital teeth. Results from studies that evaluate cements for post retention by pulling posts out of extracted teeth are difficult to interpret owing to the number of interfaces where fracture might occur. The objective of this study was to isolate the metal/cement interface for tensile bond strength testing and microscopic observation. Methods. Three metals and seven cement treatments were examined for bond strength by using a truncated cone tensile test. The bond strength data were analyzed by a two-way ANOVA and Scheffé's multiple comparison test at p=0.05. Specimens were examined at 50× magnification to determine the failure mode and with scanning electron microscopy (500×) to observe the surfaces after debonding. Results. Significant differences in tensile bond strengths were found among cements compared within two of the metal groups. One of the metal groups had no significant differences among cement bonds. When comparing within cement treatment groups, two groups had significant differences in bond strength among the metals. Microscopic observations revealed adhesive, cohesive and mixed failure modes that varied with cement treatment and metal combination. The interaction between metal and cement was a critical determinant of the strength and characteristic fracture mode of the bond achieved. Significance. Some of the cement treatments performed better (i.e., higher bond strength) with some metals than with others. Other cements had similar bond strengths with all three metals. Because of this interaction, careful consideration of the materials combination should help to maximize the bond at the metal/cement interface.

Comparison of bond strengths of three denture base resins to treated nickel-chromium-beryllium alloy

Purpose. In-vitro bond strengths of 3 denture base resins (Trutone, Lucitone 199, and Triad) to a nickel-chromium-beryllium removable partial denture alloy (Ticonium) were tested with 3 surface pretreatments: sandblast, acid etch, and Rocatec (silica blasting), with or without primers (Dentsply, CR inlay cement, and Super Bond). Material and methods. Lucitone 199 denture base resin bonded to the nonprimed sandblasted alloy specimen served as the control group. Alloy specimens were prepared, surface treated, and primed or not primed with primer. The treated specimens were then packed and processed with the denture base resin. Bonded specimens were stored in the distilled water at 37°C for 24 hours, and then debonded in tension. The force at which the bond failed was noted, and bond strength was calculated in megapascals (MPa). Five replications for each condition (180 specimens total) were tested. Results. Significant differences in bond strength were observed with primer, the most important factor, followed by pretreatment and denture base resin. Without primer for all 3 denture base resins, the Met-Etch and Rocatec treated groups showed significantly higher bond strengths than the sandblasted groups. For Trutone denture base resin, nonprimed treated groups produced significantly higher bond strength than those for the other 2 denture base resins. The control group had zero bond strength. For Dentsply primer, the Rocatec treated group bonded to Lucitone 199 resin produced the highest bond strength value (14.8 ± 1.8 MPa). For CR inlay cement, the Met-Etch and Rocatec treated groups for Lucitone denture base resin demonstrated the highest bond strength (19.3 ± 4.8 MPa, and 19.3 ± 1.8 MPa, respectively). For Super Bond primer, the Met-Etch treated group for Trutone resin demonstrated the highest bond strength (19.8 ± 6.2 MPa). Conclusions. Without primer, the control had the lowest bond strength (0 MPa), and the Trutone groups showed the highest bond strength (11.7 ± 4.1 MPa). Met-Etch and Rocatec treated groups produced higher bond strengths than the sand blasted groups. The primed specimens demonstrated significantly higher bond strengths than nonprimed specimens, except for Trutone resin, for which primed specimens produced lower bond strengths than the nonprimed specimens. (J Prosthet Dent 1998;80:354-61.)

Effect of ceramic surface treatments on the bond of four resin luting agents to a ceramic material

Purpose. This study evaluated the effect of various ceramic surface treatments on the shear bond strengths of four resin luting agents to Cerec 2 ceramic material. Material and methods. Four ceramic surface treatments were performed. All groups were subjected to the control treatment, which was abrasion with No. 600 silicon carbide paper. The other three group treatments were etching with phosphoric acid gel, application of bonding agent containing silane coupler, and application of silane coupling agent after etching with phosphoric acid gel. Cerec 2 ceramic specimens were treated with one of the four methods and then cemented together with each of the four resin luting agents (Super-Bond C&B, Panavia 21, Clapearl, and Vita Cerec Duo Cement). Half of the specimens were stored in water and the other half were thermal cycled before shear bond strength testing. Results. Treatment with the silane coupler improved the shear bond strength compared only with the abrasion with carbide paper (control). When the ceramic material was treated with the silane coupler or the silane coupling agent after etching with phosphoric acid gel, no significant differences in bond strength were noted between water storage and 20,000 thermal cycles for any of the four resin luting agents. After 20,000 thermal cycles, all specimens treated with the silane coupling agent with phosphoric acid gel except those cemented with Super-Bond C&B resin luting agent after etching showed cohesive failures within the ceramic. Conclusion. Combined surface treatment of etching with phosphoric acid and application of silane coupling agent provides the highest bond strengths of resin luting agents to Cerec 2 ceramic material after thermal cycling. (J Prosthet Dent 1998;79:508-13.)

Bonding strengths of porcelain repair systems with various surface treatments

Statement of problem. Metal porcelain combined surfaces are often involved in the repairing of fractured porcelain fused to metal restoration. Purpose. This study investigated the effect of surface treatments on the bonding strength of porcelain fused to metal prosthesis repair. Material and methods. Specimens (8 × 4 mm) were fabricated with Biobond II casting alloy and randomly divided into three surface groups: metal, porcelain, and metal-porcelain combined surface. Biobond porcelain system and commercially available porcelain repair systems were tested. The metal surface group was further divided into two subgroups: control and sandblasting treatment (Al 2 O 3 , 50 μm, 20 seconds). In the porcelain surface group, there were three subgroups: (1) control, (2) sandblasting, and (3) 9.5% hydrofluoric acid etching for 4 minutes. The metal-porcelain surface combined group was divided into three subgroups: (1) control, (2) sandblasting, and (3) sandblasting and etching. The manufacturer's instructions for repair systems were followed for specimen preparation. Shear bond strengths of 10 specimens for each subgroup were determined with a universal testing machine after storing in distilled water at 37° C for 7 days. The data were analyzed with analysis of variance and Scheffé F-test at the 95% significance level. Results. The Liner-M repair system showed significantly greater strength than the other tested systems on the metal surface with or without sandblasting treatment ( p < 0.05). On the porcelain surface, the strengths of sandblasting and etching subgroups ranged from 7.2 to 16.8 MPa, and 6.8 to 16.8 MPa, respectively. There were no significant differences in bond strengths between sandblasting and combined treatment of the metal-porcelain combined surface group ( p > 0.05). Conclusion. The results of this study suggest that metal substrates treated with sandblasting and porcelain treated with either hydrofluoric acid or sandblasting can increase repair strength. (J Prosthet Dent 1997;78:267-74.)

Evaluation of Scotchbond multipurpose and maleic acid as alternative methods of bonding orthodontic brackets

Damage to the enamel surface during bonding and debonding of orthodontic brackets is a clinical concern. Alternative bonding methods that minimize enamel surface damage while maintaining a clinically useful bond strength is an aim of current research. The purpose of this study was to compare the effects on bond strength and bracket failure location of two adhesives (System 1+ and Scotchbond Multipurpose, 3M Dental Products Division) and two enamel conditioners (37% phosphoric acid and 10% maleic acid). Forty-eight freshly extracted human premolars were pumiced and divided into four groups of 12 teeth, and metal orthodontic brackets were attached to the enamel surface by one of four protocols: (1) System 1+ and phosphoric acid, (2) Scotchbond and phosphoric acid, (3) System 1+ and maleic acid, and (4) Scotchbond and maleic acid. After bracket attachment, the teeth were mounted in phenolic rings and stored in deionized water at 37° C for 72 hours. A Zwick universal testing machine (Zwick GmbH & Co.) was used to determine shear bond strengths. The residual adhesive on the enamel surface was evaluated with the Adhesive Remnant Index. The analysis of variance was used to compare the four groups. Significance was predetermined at p ≤ 0.05. The results indicated that there were no significant differences in bond strength among the four groups ( p = 0.386). The results of the Chi square test, evaluating the residual adhesives on the enamel surfaces, revealed significant differences among the four groups (χ 2 = 0.005). A Duncan multiple range test revealed the difference occurred between the phosphoric acid and maleic acid groups, with maleic acid having bond failures at the enamel-adhesive interface. In conclusion, the use of Scotchbond Multipurpose and/or maleic acid does not significantly effect bond strength, however, the use of maleic acid resulted in an unfavorable bond failure location. (Am J Orthod Dentofac Orthop 1997;111:498-501.)

In vitro peel/shear bond strength of orthodontic adhesives

Objectives: The purpose of this study was to evaluate the in vitro peel/shear bond strength of a selection of orthodontic bracket adhesives to human premolar teeth. Methods: Twenty-two commercially available bracket adhesives were used to bond the same bracket type (Miniature Twin, 3M Unitek, Monrovia, CA, USA) on 264 intact human premolar teeth and then adhesively tested to failure. Peel/shear bond strength values were calculated in newtons and megapascals. The site of bond failure was scored according to the Adhesive Remnant Index. Statistics included one-way analysis of variance and Tukey's Studentized Range test together with Weibull analysis. The latter is a survival analysis able to describe the performance of a material. Results: The mean bond strengths varied from 9.9 MPa for Concise to 4.1 MPa for Heliosit Orthodontic. The overall F-test showed a significant difference ( P < 0.0001). No significant differences in bond strength were found between Concise, AccuBond, Imperva Dual, Transbond XT, Kurasper and Spectrum. Conclusion: Concise and AccuBond are among the materials of choice for bonding fixed orthodontic appliances to teeth. These materials combine high bond strength with a reliable bond that is easily and quickly debonded.

In vitro peel/shear bond strength evaluation of orthodontic bracket base design

Objectives: The adhesive capacity of 17 different bracket types was evaluated in an in vitro peel/shear test. Methods: Silane-treated metal bars were used as substrates with all bonding being performed using the orthodontic adhesive Concise. The effect of aluminium oxide air abrasion on the bonding performance of recycled metal bracket bases was evaluated. Morphological examination of the bracket bases was carried out under scanning electron microscopy. Statistics analysis included one-way ANOVA with Tukey's Studentized Range Test, two-way ANOVA and Weibull analysis. Results: Mean peel/shear bond strength values range from 13.9 MPa for Allure Accu Arch, a ceramic bracket type, to 1.6 MPa for the plastic bracket CeramaFlex Advant Edge. Allure Accu Arch performed the best of all the ceramic brackets. However, bracket wing fracture was observed. The metal brackets Mini masters and Omni Arch showed no significant difference in bond strength compared with the ceramic bracket Allure Accu Arch ( P < 0.01). Conclusion: The type of the bracket base determines its adhesive capacity. Sandblasting the base of recycled metal brackets had no uniform effect.

Enamel preparation for orthodontic bonding: A comparison between the use of a sandblaster and current techniques

Four methods of enamel preparation before orthodontic bonding that are currently in use or proposed for use were investigated. The study consisted of two parts. Part one evaluated the roughness of the prepared enamel surfaces by using optical profilometry and scanning electron microscopy (SEM). Part two compared the debonding force for the prepared enamel surfaces by using a mechanical testing machine. The teeth were divided into four groups as follows: In group A, the surfaces were only sandblasted. In group B, the surfaces were sandblasted and acid etched. In group C, the surfaces were buffed with an 1172 fluted bur and acid etched. In group D, the surfaces were pumiced and acid etched. There was no statistical difference in surface roughness among the four groups at p < 0.05, nor was there any statistical difference in bond strength among the three groups that were acid etched. However, there was a significant difference in bond strength between these groups and the group that received only sandblasting (no acid etching). Thus, in this preliminary study, sandblasting does not appear to damage the enamel surface and can therefore be used as a substitute for polishing with pumice. It should be followed by acid etching to produce enamel surfaces with comparable bond strengths.