3M Single Bond Research Articles

Influence of Age and Etching Technique on the Microleakage in Class-V Composite Restorations: An In-vitro Study

Aim: The objective of current research was to evaluate the impact of patient’s age on the microleakage in Class-V composite restorations. Study Design: Research article. Methodology: 30 permanent human molars from various age groups (n=10 each) were collected. The teeth were categorized based on age, Group I (less than 30 years), Group II (30-50 years), and Group III (more than 50 years), standardized Class-V tooth preparations were prepared. Subsequently, each group has further two subgroups: selective enamel etching (Sb A) and self-etching (Sb B), using universal adhesive (3M single bond). Following this, restoration of teeth were done using Z350 composite, and microleakage was analysed by dye penetration method via stereomicroscope and corresponding scoring were recorded. Mann- Whitney Test and Kruskal- Wallis Test was done for statistical analysis. Results: The group III subgroup A and B showed highest microleakage (2.40 and 2.80) followed by group II (1.20 and 1.60) and least in group I (0.40 and 0.80) respectively (P<.005). Therefore, more microleakage was seen with self-etch group as compare to selective etch. Conclusion: Influence of age of patient had significant impact on Class-V restorations. Also, more microleakage was observed in self-etch group as compared to that of selective etch technique.

Effect of Time and Temperature of Air Jet on the Mechanical and Biological Behavior of a Universal Adhesive System.

To evaluate the influence of heat application on the degree of conversion (DC) of the 3M Single Bond Universal Adhesive System, as well as its transdentinal cytotoxicity and microtensile bond strength to dentin. Experimental groups were established according to the time and temperature of the air jet: G1: 5 seconds-25°C; G2: 10 seconds-25°C; G3: 20 seconds-25°C; G4: 5 seconds-50°C; G5: 10 seconds-50°C; G6: 20 seconds-50°C. In control group (G7), no treatment was performed. The DC was assessed using the Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) technique. For the transdentinal cytotoxicity test, dentin discs fitted in artificial pulp chambers (APC) received the application of the adhesive system and the air jets. For the microtensile bond strength, healthy molars were restored and submitted to the microtensile test after 24 hours and 6 months, respectively. Significant reduction in viability of Mouse Dental Papilla Cell-23 (MDPC-23), which exhibited morphological changes, was observed in all experimental groups compared to control (p<0.05). Although all tested protocols resulted in transdentinal diffusion of 2-hydroxyethyl methacrylate (HEMA), the group G6 presented the highest degree of monomeric conversion and the lowest cytotoxic effect, with higher dentin bond strength values in comparison to group G1 (p<0.05). Applying an air blast at 50°C for 20 seconds increases the DC and microtensile bond strength of the 3M Single Bond Universal Adhesive System to dentin, as well as reduces the transdentinal cytotoxicity of the material to pulp cells.

Fabrication and Use of a Customized Provisional Composite Abutment in Dental Practice

Introduction Reducing the time of implant integration and the period of prosthetics is an important task of dentistry since this leads to improved quality of life and successful rehabilitation of the patient. Therefore, currently, there is an intensely increased interest in immediate or early loading of the implant, when certain parameters of primary implant stability in the bone tissue are achieved. Materials and Methods The materials used to perform the procedure for placement of a customized provisional composite abutment were a provisional prefabricated abutment with a retention grip for the composite; aluminum oxide powder with a particle size of 27 μm for better adhesion of the composite, with which the retention grip of the provisional abutment is coated; 3M Single Bond Universal light-curing adhesive applied to the provisional abutment; and Filtek Bulk Fill 3M composite including a low-viscosity radiopaque nanocomponent and ytterbium trifluoride filler with a particle size of 0.01–3.5 nm. Methods used in this study were as follows: fabrication technique using the Cervico system for a customized provisional composite abutment; sandblasting of the provisional abutment using the apparatus RONDOFLEX (KERR); light polymerization of low-viscosity composite using Demi Ultra Kerr lamp (luminous flux power not less than 1100 mW/cm2); and radiographic control of the abutment fit in the implant. Results The surgical and orthopedic treatment of 20 patients was performed using this technique. The control group consisted of 11 patients with similar pathology, in whose surgery the fabrication of a provisional prosthesis was used. As a result, it was possible to form a gingival profile, in comparison with the control group, to accelerate mucogingival and bone integration, as well as to quickly carry out orthopedic rehabilitation of the patient. The average value of the time required for the final formation of soft tissues for prosthetics in patients in the experimental group was significantly lower than those in the comparison group (p=0.007 and p=0.028, respectively). In most clinical cases, there is no need for surgery on soft tissues, which eliminates the possibility of additional traumas. Conclusions The use of a promising technology for the fabrication of a crown on the implant and a customized provisional composite abutment significantly reduced the period of orthopedic rehabilitation of the patient. Immediate implantation with a customized provisional composite abutment completely forms the gingival profile, reduces the risk of microbial contamination in the area of bone formation, minimizes soft tissue ischemia, and accelerates the processes of mucogingival and bone integration around the implant.

Effect of bioactive glass pretreatment on the durability of dentin bonding interface

To study the effect of bioactive glass (BG) on the dentin bond strength and the microleakage of hybrid layer. In the study, 30 dentin planes were prepared from the third molars with no caries and equally assigned to the control group, BG group, and sodium trimetaphosphate (STMP)-polyacrylic acid (PAA)-BG group (S-P-BG group), randomly. After etched with 35% phosphoric acid, the dentin planes of BG group were pretreated with 0.5 g/L BG, and the dentin planes of S-P-BG group were pretreated with 5% STMP, 5% PAA and 0.5 g/L BG. No additional pretreatment was done to the dentin planes of control group. Then the dentin planes were bonded using 3M Single Bond 2 adhesive to 3M Z350XT composite resin, and cut into 0.9 mm×0.9 mm column samples, which were stored at 37 ℃ artificial saliva (AS). After 24 hours, 1 month, and 3 months, the microtensile bond strength test was performed. The data were analyzed using one-way ANOVA and LSD method. The morphology of the bond fracture interface was observed with scanning electron microscope. Other 27 teeth were collected and the enamel layer and roots cut off, with the pulp chamber exposed. 0.1% rhodamine B was added to the 3M Single Bond 2 adhesive, and then the adhesive was applied to complete the bonding procedures as above. The teeth were stored in 37 ℃ AS for 24 hours, 1 month, 3 months, and then 0.1% sodium fluorescein solution was placed in the chambers and stained for 1 hour. Confocal laser scanning microscopy was used to observe the interface morphology and microleakage of the hybrid layer. At the end of 24 hours and 1 month, there was no significant difference in the microtensile bond strength among the three groups (P>0.05). After 3 months of soaking, the S-P-BG group [(36.91±7.07) MPa] had significantly higher microtensile bond strength than the control group [(32.73±8.06) MPa] (P=0.026); For the control group and the BG group, the microtensile bond strength significantly decreased at the end of 3 months compared with 24 hours (control group: P=0.017, BG group: P=0.01); The microtensile bond strength of S-P-BG group af the end of 3 months had no significant difference in compared with 24 hours [(37.99±7.98) MPa] (P>0.05). Observation of the fracture surface at the 24 hours showed no obvious mineralization in all the three groups. After 1 and 3 months, mineral formation was observed in BG group and S-P-BG group, and no obvious collagen exposure was observed in S-P-BG group. Confocal laser scanning microscopy revealed no obvious differences in the morphology and quantity of the resin tag in the control group, BG group and S-P-BG group. At the end of 24 hours, leakage was found in all the three groups. The microleakage of the control group increased at the end of 3 months, while the microleakage of the BG and S-P-BG groups decreased. BG pretreatment of dentin bonding interface can induce mineralization at the bonding interface and reduce the microleakage of the hybrid layer; pretreating the dentin bonding interface with STMP, PAA and BG may enhance the maintaining of the dentin bonding durability.

Effect of Different Surface Treatments on Bond Strength of Resin Cement to a CAD/CAM Restorative Material.

To investigate the effects of various surface treatment methods on the shear bond strength of self-adhesive resin cement to a novel CAD/CAM hybrid ceramic material. A novel hybrid ceramic restorative material (Vita Enamic) was used in this study. Sixty resin block specimens were prepared and separated into six groups for each surface treatment method (n = 10); group 1: control group, no treatment applied; group 2: sandblasted by 30 μm silicate-coated alumina particles (CoJet Sandblasting); group 3: 50 μm Al2 O3 sandblasting; group 4: 10% hydrofluoric acid; group 5: no surface treatment + universal adhesive (3M Single Bond Universal); group 6: 200 mJ, 10 Hz 2W Er,Cr:YSGG laser treatment. For each specimen, surface roughness measurements in noncontact mode were taken after the surface treatments using a portable surface texture-measuring machine. A self-adhesive resin cement (3M U200) was applied on every surface treated with the help of a cylindrical mold (2 × 4 mm) and was filled gradually. Shear bond strength was measured using a universal test machine, and one-way ANOVA and a Duncan test (p = 0.05) were used to analyze the data. Mean values of the shear bond strength varied between 7.75 and 10.73 MPa. Bond strength values were enhanced by all surface treatment methods compared to the control group. The difference between group 5 and the control group (p < 0.05) was statistically significant, whereas there were no considerable differences between other treatment methods. Surface treatments of hybrid ceramic resin blocks could enhance the bond strength to resin cement; however, using Single Bond Universal without surface treatment showed a higher bond strength value.

Üç farklı universal adeziv sistemin dentine makaslama bağlanma dayanımlarının karşılaştırılması

Background: The aim of this study is to compare shear bond strengths of three universal adhesives (3M ESPE Single Bond Universal, G-aenial Bond, (GC, Japan), Clearfil Universal Bond, (Kuraray, Japan) to dentin. Methods: 36 freshly extracted noncarious molar were selected for this study. Occlusal flat dentin surfaces were exposed by cuttuing occlusal enamel and by 600, 800, 1000, 1200 grid paper, standard smear layer was obtained. The teeth were randomly divided into three groups (n=12). Group 1: 3M Single Bond Universal, Group 2: G-aenial Bond (GC, Japan) Group 3: Clearfil Universal Bond (Kuraray, Japan). Adhesives were applied to dentine according to the manufacturers' instructions. The resin composite (Tetric EvoCeram, Ivoclar, Vivadent, Sweeden) of each adhesive system was applied on the bonded dentin surface using an application apparatus (Ultradent Products Inc.). The materials were light-cured according to the manufacturers' instructions by a LED. After 24 hour storage in distilled water at room temperature, the shear bond test was carried out using a universal testing machine with a cross head speed 0.5mm/min. The data were analyzed with One Way ANOVA and post-hoc Tukey tests. Fracture analyzes of all samples were done using a light microscope. Results: Statistical analysis showed no significant differences in shear bond strengths between three groups (p>0.05). 3M Single Bond Universal (14,44 ± 3,38 mPa), G-aenial Bond (12,32 ± 3,75 mPa), Clearfil Universal Bond (11,30 ± 2,92 mPa). Clearfil Universal Bond showed the lowest shear bond strength to dentin. Conclusion: The three tested universal adhesive systems showed similar shear bond strength to dentin. These results should be supported by clinical practice.

English

INTRODUCTION: The concept of adhesive dentistry has taken leaps forward and has resulted in a concept of more conservation of tooth structure which in turn enhance the life of teeth. The bonding agent forms a hybrid layer with dentin and its other side co-polymerize with the matrix phase of dental composite, producing strong micro-mechanical bonding. AIMS AND OBJECTIVE: To evaluate the bond strength of adhesive agent to normal dentin and caries affected dentin and also to compare the bond strength between different bonding agents. METHOD: 20 mandibular molar were collected, washed and stored in normal saline. Each tooth was cut longitudinally. Healthy tooth structure of each half of the tooth represents the control group and the carious portion of the same tooth represents as experimental group. Thus, 80 samples were prepared. The groups were then further subdivided into 4 sub-groups of 4 different bonding agents. The dentin surface of all the sub groups were etched by 37% of phosphoric acid gel for 10-15 secs and respective bonding agent were used and cured for 20 secs. Cylindrical composite resin was prepared using a plastic module of internal diameter of 3mm and length 5mm. Statistical analysis was done using mean standard deviation (S.D), student 't' test and level of significance 'P'. RESULTS: For both the control and experimental group, 3M single bond has showed the strongest bond strength followed by Prime and Bond NT, Excite and PQ1.

Effect of 10% Sodium Ascorbate on Shear Bond Strength of Bleached Teeth - An in-vitro Study.

Patient often requires some additional interventions such as replacement of old restorations, laminates and veneers after bleaching, for aesthetic purposes. The residual oxygen inhibits polymerization of resin based materials which results in reduced bond strength of the restorations. Some techniques are available to solve the clinical problems related to the post bleach compromised bond strength. The purpose of this study is to evaluate, the role of 10% sodium ascorbate on reversing the compromised bond strength and compare enamel shear bond strength of 5th and 6th generation dentine bonding agents on bleached and unbleached teeth. Eighty freshly extracted human anterior teeth were assigned in to Group A and Group B of 40 teeth each. Samples in both groups were subdivided in to 4 subgroups of 10 teeth each. In Group A composite resins was bonded using 5th generation dentine bonding agent (3M Single Bond) and Group B was bonded using 6th generation (3M ESPE Adper SE Plus). Subgroups were subjected to the procedure as, A1;B1 etching and bonding (control), A2; B2 bleaching, etching and immediate bonding, A3; B3 bleaching,10% ascorbic acid treatment for 10 minutes after that etching and bonding immediately, A4; B4 bleaching, storage in artificial saliva for 4 days and then etching and bonding. Pola office, in office bleach (SDI (082216) was used for bleaching. The specimens were subjected to shear load in a Universal testing machine to evaluate bond strength. A decrease in bond strength was seen with 6th generation adhesive system compared to 5th generation bonding system, which is statistically significant, p<0.001. Treating the bleached enamel surfaces when treated with 10% sodium ascorbate, which reverses the compromised bond strength and is a good alternative to delayed bonding.

Evaluation of cytotoxicity of resin bonding materials toward human oral epithelial cells using three assay systems

Background/purpose Gingival tissue around teeth can be contacted by flowable photocured resin agents during operative procedures. The cytotoxicity of resin bonding agents toward human oral epithelial cells cannot be neglected. This study evaluates the cytotoxicity of resin bonding agents toward human oral epithelial cells using three assay systems. Materials and methods Nine commercial resin bonding agents (Clearfil Protect Bond, Clearfil SE Bond, Prime & Bond NT, Prisma Universal Bond 3, UniFil Bond, 3M Single Bond, CharmBond, Compobond, and ExciTE) and two resin monomers (methyl methacrylate and triethylene glycol dimethacrylate) were used. The detection methods for the cell survival rate included: (1) the CellTiter 96 AQueous One Solution Cell Proliferation Assay System, (2) PreMix WST-1 Cell Proliferation Assay System, and (3) CellTiter-Glo Luminescent Cell Viability Assay System. One-way analysis of variance and Scheffe test were used for the statistical analyses. Results Most of the components of the uncured bonding agents had cytotoxicity at 0.1 vol% (survival rates, 21.4% ± 1.4% to 113.1% ± 19.1%), except for UniFil Bond Primer (survival rates, 101.8% ± 3.5% to 113.1% ± 19.1%). More severe cytotoxicity was found at the 1.0 vol% concentration (survival rates, 0.2% ± 0.02% to 147.3% ± 10.8%), except for the methyl methacrylate monomer (survival rates, 96.5% ± 1.3% to 147.3% ± 10.8%). In the post-cured group, most bonding agents had little or no cytotoxicity, except for 3M Single Bond (survival rates, 52.4% ± 7.9% to 97.4% ± 17.8%) and Compobond (survival rates, 29.1% ± 7.1% to 79.5% ± 6.7%). Conclusion The same material detected by different assay systems may give different cytotoxic effects, and examination by three methods may provide more-objective results. Furthermore, since most of the bonding agent components detected by the three assay systems showed cytotoxicity before curing (and some components even showed cytotoxicity after curing), the application of bonding materials in the oral cavity should be very carefully performed.

A Comparative Evaluation of Tensile Bond Strength and Hybrid Layer of Three Generation Bonding Agents by Scanning Electron Microscope (An In-vitro Study)

ABSTRACT This study was done to compare the tensile bond strength of three different generation bonding agents to dentin using one composite resin and scanning electron microscopic study (SEM) of hybrid layer. In this study 36 non carious human molar teeth were selected. 30 teeth were used for evaluating tensile bond strength and were divided in to three groups. Six teeth were used for hybrid layer evaluation also divided into three groups. Group 1 specimens 10 teeth were etched with 37% phosphoric acid and Scotch bond multipurpose adhesive was applied. Group 2 specimens 10 teeth were etched with 37% phosphoric acid and 3M Single bond was applied. Group 3 specimens 10 teeth were treated with Prompt-L-Pop. Composite material (3M- Hybrid-Z100) was applied incrementally and cured for 40 seconds each. Specimens were then stored in distilled water before testing. Two teeth from each group were cross-sectioned to obtain 1mm thick dentin disks for SEM evaluation. Adhesives were applied as mentioned above. Composite was applied over these discs and light cured for 40 seconds. Samples were stored in distilled water at 37°c for two weeks; these disks were fractured with chisel for cross-sectional viewing Dentin conditioning with single bond (5th Generation) revealed better bond strengths as compared to scotch bond multipurpose (4th generation) and Prompt-L-Pop (6th generation). SEM evaluation of hybrid layer reveals that Single bond has shown a thicker hybrid layer comparing to other adhesives.

Vasorelaxant Effect of Resin-Based, Single-Bottle Dentin Bonding Systems

Single-bottle dentin bonding systems are currently in wide use. Because these materials are sometimes inadvertently placed on microscopic pulp exposures while at other times deliberately on frank exposures, their effects on pulpal soft tissues need to be evaluated. The present study assessed the vascular effects of 3M Single Bond (3MSB) and Prime & Bond NT (PBNT), using rat aortic ring preparations. It is hypothesized that these bonding agents induce relaxation of these preparations. Both 3MSB and PBNT caused endothelium-dependent and -independent relaxations in a concentration-dependent manner. The endothelium-dependent relaxation was associated with the release of nitric oxide. However, the responses to both agents did not involve the generation of prostanoids or K ATP channel activation. At relatively low concentrations, the responses of endothelium-denuded tissues to 3MSB were greater than those to PBNT, indicating certain differences in the vascular action between these products. The data suggest that 3MSB and PBNT interfere with vascular function by causing vasorelaxation via mechanisms occurring in the smooth muscle and endothelium, including the release of nitric oxide. Among others, this effect may promote bleeding if these adhesives are placed on pulp exposures.

A comparative evaluation of tensile bond strength and scanning electron microscopic study of three generation bonding agents. An in-vitro study

This study was done to compare the tensile bond strength of three different generation bonding agents to dentin using one composite resin and scanning electron microscopic study (SEM) of hybrid laver.<br>In this study 36 non carious human molar teeth were selected. 30 teeth were used for evaluating tensile bond strength and were divided in to three groups. Six teeth were used for hybrid layer evaluation also divided into three groups. Group 1 specimens 10 teeth were etched with 37% phosphoric acid and Scotch bond multipurpose adhesive was applied. Group 2 specimens 10 teeth were etched with 37% phosphoric acid and 3M Single bond was applied. Group 3 specimens 10 teeth were treated with Prompt-L-Pop. Composite material (3M-Hybrid­Z100) was applied incrementally and cured for 40 seconds each. Specimens were then stored in distilled water before testing. Two teeth from each group were cross-sectioned to obtain 1mm thick dentin disks for SEM evaluation. Adhesives were applied as mentioned above. Composite was applied over these discs and light cured for 40 seconds. Samples were stored in distilled water at 37⁰ c for two weeks; these disks were fractured with chisel for cross-sectional viewing<br>Dentin conditioning with single bond (5^th Generation) revealed better bond strengths as compared to scotch bond multipurpose (4^th generation) and Prompt­L-Pop (6^th generation). SEM evaluation of hybrid liner reveals that Single bond has shown a thicker hybrid layer comparing to other adhesives.

Overestimating hybrid layer quality in polished adhesive/dentin interfaces.

The most popular techniques for determining the quality of the hybrid layer (HL) have relied on morphologic characterization of the polished adhesive/dentin (a/d) interfaces before and after acid-bleach chemical treatment. Using these techniques, the existence of smooth, acid-resistant layers has been consistently reported for most adhesive systems. The purpose of this study was to determine whether popular specimen preparation techniques that include polishing and acid-bleach treatment modify the a/d interface, mask the complexity of the HL, and lead to inaccurate assessment of the quality of the HL. To understand the impact of specimen preparation techniques on the morphology of the resin-dentin interface, polished and unpolished specimens from the same tooth were closely compared after different acid-bleach chemical treatment procedures. Two one-bottle adhesives, that is, 3M Single Bond and Pulpdent UNO, exhibiting distinct differences in hydrophilic/hydrophobic composition, were used in this investigation. Using specimens from the same tooth, the effect of chemical treatments on the morphology of the resin-dentin interdiffusion zone and the differences in the morphology of polished and unpolished specimens after these same treatments were studied with scanning electron microscopy. It was shown that conventional specimen preparation techniques that include polishing and acid-bleach treatment can adversely affect and even obscure the structural detail of the a/d interface in specimens that possess a porous HL. The results indicated that the Pulpdent UNO/dentin interface had better quality than the 3M Single Bond/dentin interface. The difference in the quality of HL can be attributed to factors such as compositional differences that impact the adhesive interaction with water, that is present within the substrate during wet bonding. The inability of the conventional acid-bleach procedure to reveal the differences in the scanning electron microscopy interfacial morphology was overcome in this investigation by using a multistep technique.

The effect of two configuration factors, time, and thermal cycling on resin to dentin bond strengths

Most in vitro testing of bonding systems is performed using specimens made in a mold with a low configuration ( C) factor (ratio of bonded/unbonded surfaces) whereas clinically the C-factor is usually much greater. This study compared the effect of thermal cycling on the measured shear bond strength of 3M Single Bond dental adhesive bonded to dentin using molds with two different C-factors. The hypothesis was that neither C-factor nor thermal cycling would affect measured bond strengths. Resin composite was bonded to human dentin in cylindrical molds with an internal diameter of 3.2 mm and either 1 mm or 2.5 mm deep. The 1 mm deep molds had a C-factor of 2.2 and the 2.5 mm deep molds had a C-factor of 4.1. Specimens were debonded either 10 min after they had been bonded to dentin, or after they had been stored for 7 days in water at 37±1°C, or after thermal cycling 5000 times for 7 days. Two-way ANOVA showed that overall both the C-factor and the storage condition had a significant effect on bond strength ( p<0.001). There was a significant interaction ( p<0.001) between the C-factor and how the specimens had been stored. The GLM/LSMEANS procedure with Sidak's adjustment for multiple comparisons showed that overall the specimens made in the mold with a high C-factor (4.1) had a lower bond strength than those that had been made in the mold with a lower (2.2) C-factor ( p<0.001). Thermal cycling had a negative effect on the bond strength only for specimens made in molds with a C-factor of 4.1 ( p<0.001).

Comparison of shear bond strength relative to two testing devices

Statement of Problem. Dentin adhesives are characterized on the basis of their bond strength to dentin; however, great variation exists within the same material depending on the testing apparatus. To realistically compare bond strengths, the testing mechanisms must be the same. Purpose. The purpose of this investigation was to use 2 testing devices to evaluate the shear bond strength of 3 single-bottle adhesives with their multistep counterparts. Material and Methods. The occlusal surfaces of 120 freshly extracted third molars were ground to expose the dentin and polished with 600-grit silicon carbide paper. Three single-bottle, (Optibond Solo Plus, 3M Single Bond, and Excite) and 3 multistep adhesives (Optibond FL, 3M MultiPurpose Plus, and Syntac) were each used to bond a composite cylinder (made from a 2.379 ±.001-mm diameter by 4-mm-high mold) of Tetric Ceram to 20 teeth. The specimens were stored in 100% humidity for 24 hours. The shear bond strength at failure was measured in kilograms and converted to megapascals for each material, using a knife (conventional method) and an Ultradent testing device on a universal testing machine (Instron) at a loading rate of 0.5 mm/min. A 2-way analysis of variance (ANOVA) test was performed comparing the 2 testing devices and the materials at P<.05. Where significant, a 1-way ANOVA test was conducted among the materials for each test group, and a Tukey multiple comparison test was used to determine significant differences among the materials tested (P<.05). An independent Student t test at P<.05 was used to determine significance between testing devices. Results. The results showed that Optibond Solo Plus (26.85 ± 8.76 MPa), Optibond FL (25.40 ± 4.44 MPa), 3M Single Bond (28.12 ± 5.01 MPa), and 3M MultiPurpose Plus (34.40 ± 7.90 MPa) had significantly higher bond strengths when tested with the Ultradent testing device. The mean values for Excite (19.47 ± 6.17 MPa) and Syntac (20.20 ± 7.07 MPa) were also higher with the Ultradent testing device, but the difference was not significant. Conclusion. Within the limitations of this study, all bonding agents tested resulted in higher mean shear bond strengths when tested with the Ultradent testing device compared with the unrestricted knife. The single-step bonding agents exhibited mean bond strengths comparable to their multistep counterparts. (J Prosthet Dent 2002;88:511-5.)

Strengths of composite bonded to base metal alloy using dentin bonding systems

Statement of Problem: Many different bonding systems are currently available that may be used to bond composite to base metal alloy. Purpose: This study measured and compared bond strengths of composite with a base metal alloy using 8 modern dentin bonding systems. Material and Methods: Base metal alloy buttons were imbedded in acrylic and ground with 120, 400, and 600 grit sandpaper, respectively. Metal surfaces were air abraded for 5 seconds with 50 μm aluminum oxide, washed for 5 seconds under running tap water, then dried with compressed air. Specimens were arbitrarily divided into 8 groups of 10 specimens. Each group was treated with 1 of 8 dentin bonding regimens. A hybrid composite (Herculite) was placed onto the treated metal surface and light polymerized. Specimens were incubated at 37°C in distilled water for 2 hours. Shear bond strengths were measured and the collected data subjected to an ANOVA, followed by multiple t -tests. Results: All-Bond 2 exhibited the highest mean shear bond strength and Panavia 21 with primer had the lowest in the tests conducted. Conclusion: All-Bond 2 demonstrated significantly higher shear bond strengths over all materials tested, except 3M Single Bond and Optibond FL. No significant difference was noted between the single component and the multicomponent bonding systems. (J Prosthet Dent 2000;84:149-53.)

Effect of removal of surface collagen fibrils on resin–dentin bonding

Objectives: The aim of this study was to evaluate the effects of NaOCl at removing the demineralized layer by examining the morphology of the hybrid layer and measuring shear bond strengths after different dentin treatments. Methods: Dentin disks were treated with: (1) 35% phosphoric acid (PA) 20 s; (2) PA treatment followed by 1.5% NaOCl, 2 min; (3) PA treatment, followed by a 10% NaOCl immersion for 120 h. SEM was used to analyze the morphology of dentin and its interface with dentin bonding agents (DBAs), while shear bond strength tests were used to measure adhesion. All specimens were then fractured into two halves: One half was inspected under SEM; the other half was sequentially placed in 10% PA followed by 12.5% NaOCl for 70 h, to remove all dentin from the resin replica of the original bonded interface. Results: SEM observations showed that collagen fibrils were completely removed from the acid-etched surface by NaOCl treatment. The diameter and the size of dentinal tubules and the number of lateral branches of the tubules were increased following NaOCl treatment. NaOCl applied on dentin smear layers did not significantly modify their SEM morphology. Resin tags were larger in diameter after phosphoric acid/NaOCl treatment than after only phosphoric acid treatment. Resin-infiltrated dentin-layers were only observed after the single phosphoric acid (i.e. conventional etching) procedure, and were not observed after combined phosphoric acid/NaOCl treatment. Etched/NaOCl samples showed a lower bond strength using Scotchbond MP and 3M Single Bond, but were higher in Optibond FL and unmodified in Prime & Bond 2.0 groups when compared with acid-etched controls. Treatment of etched dentin with NaOCl for 120 h produced an unusual type of resin infiltration of mineralized dentin that could be called a “reverse hybrid layer” which may explain the mechanism of resin bonding to NaOCl treated dentin. Significance: The use of acidic conditioners for exposure of the collagen matrix exposes a soft delicate mesh that can collapse, thereby interfering with resin infiltration. If acid-etching is followed by NaOCl treatment, high bond strengths can be achieved via “reverse hybrid layer” formation, a proposed new mechanism of micromechanical resin retention. This mechanism is not yet recommended for clinical use but demonstrates a new type of resin retention.