Bond strengths and SEM evaluation of Clearfil Liner Bond 2

PURPOSE: To evaluate a dental adhesive system that uses a single conditioning/primer agent. MATERIALS AND METHODS: Twenty-five flat enamel and dentin bonding sites were prepared to 600 grit on human molar teeth. The Clearfil Liner Bond 2 adhesive system was used to bond Clearfil AP-X composite to both enamel and dentin. After 24 hours of water storage, shear bond strengths were determined using an Instron testing machine. Fifty V-shaped cavity preparations were prepared in human molar teeth with an enamel and cementum margin. Composite restorations were placed using the new adhesive system. The teeth were stored for 24 hours, thermocycled, stained with AgNO3 , sectioned and examined for microleakage. SEM examinations were also completed to evaluate the effects of the treatment steps on enamel and dentin surfaces. RESULTS: Mean shear bond strengths for the experimental adhesive to enamel and dentin were 28.2 +/- 4.9 and 19.4 +/- 3.1 MPa. A t-test revealed that the enamel bond strength was significantly greater (P<0.05) than the dentin strength. No marginal leakage was observed from the enamel margins of the restorations. Three restorations showed minimal leakage from the cementum margins. SEM examinations showed resin penetration into both the conditioned enamel and dentin surfaces. The adhesive system produced high bond strengths to both enamel and dentin, exhibited very minimal microleakage and was easy to use.     

Cysteine and glutathione deficiency in AIDS patients: a rationale for the treatment with N-acetyl-cysteine

The purpose of this study was to determine the effect of accidental dentin primer contact with etched enamel on shear bond strength of composite resin to enamel. Four dentin bonding systems were included in this study: GLUMA Dentin Bond, Scotchbond, and Prisma Universal Bond 2 and 3. Eighty extracted human permanent anterior teeth were used and divided in eight test groups. The vestibular surfaces were ground and acid etched. For each dentin bonding system 10 samples were treated with dentin primer prior to placement of resin. Shear bond testing showed that enamel contact with dentin primer in the above two systems decreased the shear bond strength between composite and enamel by 31 to 44%.     

Starch utilization by Bacteroides ovatus isolated from the human large intestine

OBJECTIVE: It was hypothesized that there is an inverse relationship between resin-enamel bond strength and bonded cross-sectional area, and that there are regional differences in resin-enamel bond strength. METHODS: The facial and lingual surfaces of extracted human third molars were ground down 0.3 mm using 240 grit abrasive paper and were then bonded with either Clearfil Liner Bond 2 or Scotchbond Multi-Purpose Plus adhesive systems using the manufacturer's instructions. The bonded surfaces then received a resin composite build-up. After 24 h of storage in water, the bonded teeth were vertically serially sectioned into 1.0 mm thick slabs using a diamond saw, and the bonded surface area at the resin-enamel interface was varied from 0.5 to 3.0 mm2 using a diamond saw under microscopic observation. The trimmed region was varied from the occlusal third of the facial or lingual enamel to the middle third, to the cervical third. The trimmed specimens were then glued to a Bencor Multi-T device, placed in an Instron testing machine and stressed to failure at 1 mm/min. A three-factor ANOVA was used to compare bond strengths (buccal vs. lingual, occlusal vs. middle vs. cervical-third, vs. materials). Regression analysis was used to examine the relationship between bond strength and bonded cross-sectional area for each material on occlusal enamel. RESULTS: For both bonding systems, there was a highly significant (p < 0.001) inverse exponential relationship between tensile bond strength (y axis) and bonded cross-sectional area (x axis) with y intercepts of 51 and 59 MPa for Clearfill Liner Bond 2 and Multi-Purpose Plus, respectively. Using both materials, the highest bond strengths were measured in the occlusal third, which were significantly higher (p < 0.05) than those made to cervical enamel. SIGNIFICANCE: Like resin-dentin bonds, resin-enamel bonds exhibit an inverse relationship with cross-sectional area. This relationship becomes more apparent at bonded surface areas below 2 mm2 and is probably due to reductions in the number of interfacial stress-raisers as samples are made smaller.     

Enamel and dentine shear bond strength of two resin modified glass ionomers and two resin based adhesives

OBJECTIVES: The purpose of this in vitro study was to compare the shear bond strength to enamel and dentine of two resin modified glass ionomers (Fuji Bond L.C. and Vitrebond) and two resin based adhesives (Prime&Bond 2.1 and Scotchbond Multi-Purpose). METHODS: A total of 120 bond sites were prepared on either enamel (n = 60) or dentine (n = 60) on human molars by grinding the teeth flat with a 600 grit sandpaper. Each tooth substrate group was divided into four groups (n = 15) to match each material. Each of the four material systems was applied, according to the manufacturers instructions, to the bond sites. On top of the placed material, a microfilled composite was placed in a 2.5 mm diameter matrix and light-cured for 40 s. All specimens were thermocycled 500 times (5-55 degrees C). Shear bond strength values were determined 120 h after bonding using a Zwick testing machine. One-way ANOVA was used to determine whether significant differences (p < 0.05) existed among the material groups on enamel and dentine. Pairwise comparisons were used to determine significant differences (p < 0.05) among the four products. RESULTS: The ANOVA revealed strong significant differences on enamel (p = 0.0001) and dentine (p = 0.0172). The enamel bond strength values of the two resin based adhesives were significantly higher than one of the resin modified glass ionomers (Vitrebond), while the other resin modified glass ionomers did not differ from Scotchbond Multi-Purpose. On dentine, however, Vitrebond performed significantly better than the two resin based adhesives. CONCLUSIONS: The investigated resin modified glass ionomers bonded better to dentine surfaces than to enamel surfaces, while the investigated resin based adhesive systems bonded better to enamel than to dentine.     

Effect of acidic primers on bonding between stainless steel and auto-polymerizing methacrylic resins

OBJECTIVES: The purpose of this study was to evaluate the effect of acidic primers on bonding between methacrylic resins and SUS 316 stainless steel. METHODS: The primers were single liquid metal conditioners containing either a phosphate monomer (Cesead opaque primer, CO; Metal primer, MP) or a carboxylic monomer (Super-Bond liquid, SB; Acryl bond, AB; MR bond, MR). Disk metal specimens were air-abraded with alumina followed by priming. The disks were bonded with a methacrylic resin using a brush-dip technique (Super-Bond C & B, CB or Repairsin, RE). Specimens were thermocycled in water and bond strengths were determined. RESULTS: Shear bond strengths after the thermocycling were 11.9 MPa for CO-CB, 7.6 MPa for CO-RE, 4.9 MPa for SB-RE, 3.9 MPa for MP-RE, 3.3 MPa for AB-RE, 2.5 MPa for MR-RE, 1.9 MPa for None-CB, and 0 MPa for None-RE. The two systems primed with CO primer showed greater bond strengths than the other groups (P < 0.05). Of the two systems conditioned with CO primer, CB resin demonstrated higher value bond strength as compared with RE resin (P < 0.05). CONCLUSION: Among the systems examined, CO primer used together with CB resin exhibited greater bond strength to SUS 316 stainless steel than other systems after the ageing test. Reduction in bond strength by thermocycling, however, was remarkable for all groups.     

Post-war changes in the outcome of pregnancy in Maternity Hospital, Kuwait

To develop a non-polymerization shrinkage adhesive resin, the effects of the contents varying 0-20 wt% radical polymerizable spirocyclic monomers of 2-methylene-1, 4, 6-trioxyaspiro [4, 6] undecane (MTSU) and 2-methylene-8, 9-benzo-1, 4, 6 trioxyaspiro [4, 4] nonane (BTSN) together with three kinds of initiator systems in adhesive resin on bonding to both Ni-Cr alloy and unetched enamel were investigated. Tensile bond strength to either Ni-Cr alloy or unetched enamel was affected by the inclusion of MTSU or BTSN, and indicated that increased contents of MTSU or BTSN resulted in decreased bond strength to the metal in the negative correlations. Regarding the bond strength to Ni-Cr alloy, however, the effective concentration of BTSN was found to be 5 wt%, and the mean bond strength was 58.5 and 58.6 MPa, respectively. The data of differential scanning calorimeter measurement, on the other hand, showed that the copolymerization of MTSU with conventional methacrylate monomers was not completely achieved.     

Dual NF1-requiring effect of human neurotropic JC virus composite pentanucleotide repeat elements on early and late viral gene expression

OBJECTIVE: The purpose of this study was to prepare a light-cured adhesive applicable for orthodontics by mixing monomers and a polymerized reactive organic composite filler (prepolymerized trimethylolpropane trimethacrylate-filler, TMPT-filler). METHODS: The monomer component was a mixture of 3.0 wt% 2-hydroxy-3-(2-naphthoxy)propyl methacrylate (HNPM) in triethylene glycol dimethacrylate. This was applied to extracted bovine tooth enamel after acid etching with 65 wt% phosphoric acid for 30 s. After 24 h in 37 degrees C water, the tensile bond strength was measured, and the data were analyzed with Duncan's new multiple range test (p < 0.01 or 0.05). RESULTS: The tensile bonding strength to enamel etched with 65 wt% phosphoric acid was 13.1 +/- 0.5 MPa, and the thermal stability of the bond was excellent. SEM examination of the cross-sectioned specimens modified with HCl demineralization showed that when the diffusion time prior to light irradiation was only 1 min, a well-developed resin honeycomb-like structure was created in the enamel surface in the formulation containing HNPM. SIGNIFICANCE: Monomer impregnation beyond the etched enamel surface was important for resin-enamel bonding, increasing bonding strength and thermal stability. HNPM was effective in enhancing monomer diffusion and impregnation of the etched enamel surface.     

The effect of dentin primer on the tensile bond strength to human enamel

Four third-generation dentin bonding products (Scotchbond Multi-Purpose, Optibond, All-Bond 2, and Prisma Universal Bond 3) were tested to evaluate their tensile bond strength to enamel. Test enamel specimens were etched, primed, and polymerized according to each manufacturer's directions. Control specimens were treated identically except the primer application was eliminated. The results demonstrated that the dentin primer significantly increased the tensile bond strength of All-Bond 2, significantly decreased the tensile bond strength of Scotchbond Multi-Purpose and Optibond, and had no significant effect for Prisma Universal Bond 3. A one-way analysis of variance was run between the eight groups tested, and three significant subsets were found (P < .05). The subset with the highest mean tensile bond strengths consisted of Prisma Universal Bond 3 primed and nonprimed, All-Bond 2 primed, and Optibond nonprimed.     

Experimental Investigation of the Influence of Moisture on the Bond Behavior of FRP to Concrete Interfaces

The effects of moisture on the initial and long-term bonding behavior of fiber reinforced polymer (FRP) sheets to concrete interfaces have been investigated by means of a two-year experimental exposure program. The research is focused on the effects of (1) moisture at the time of FRP installation, in this paper termed “construction moisture,” consisting of concrete substratum surface moisture and external air moisture; and (2) moisture, in this paper termed “service moisture,” which normally varies throughout the service life of concrete. Concrete beams with FRP bonded to their soffits were prepared. Before bonding, concrete substrates were preconditioned with different moisture contents and treated with different primers. The FRP bonded concrete beams were then cured under different humidity conditions before being subjected to combined wet/dry (WD) and thermal cycling regimes to accelerate the exposure effects. Adhesives with different elastic moduli were used to investigate the long-term durability of each adhesive when subjected to accelerated WD cycling. Pull-off tests and bending tests were conducted at the beginning of the cycling and then again after 8 months, 14 months, and 2 years of exposure so as to evaluate the tensile and shear performance of the FRP-to-concrete interfaces. It was found that the effect of the concrete substrate moisture content on short-term interfacial bond performance could be eliminated if an appropriate primer was used. All FRP-to-concrete bonded joints failed at the interface between the primer and concrete after exposure while those not exposed usually failed within the concrete substrate. After exposure to an environment of accelerated WD cycles, it was also found that the interfacial tensile bond strength degraded asymptotically with the exposure time while the flexural capacity of the FRP sheet bonded plain concrete beams even increased. The mechanism behind the above, which is an apparently contradictory phenomenon, is discussed.     

Bond strength of permanent soft denture liners bonded to the denture base

The purpose of this study was to characterize denture and soft liner adhesion and to determine the adhesive and/or cohesive strength of different soft tissue liners bonded to the denture base by use of a new technique. Two groups of five permanent soft liners (dry or exposed to water for 6 months) were tested by use of a tensile mode to characterize the failure characteristics of soft liners bonded to denture base resin. The method differed from previous test methods because of the specimen's ability to align axially during the test. The results indicated significant differences in the bonding of liners to the denture base, and light-cure systems exhibited the greatest amount of stress needed for failure. Low bond strength was observed when the adhesion was poor or when the cohesive strength of the soft liner was low and lead to pure adhesive or cohesive failure. When both adhesive and cohesive bonds were strong, failure occurred at high stresses. Combinations of adhesive and cohesive failures (mixed mode) were also observed in intermediate cases.     

Dentastic bond strength to dentin

PURPOSE: To evaluate the shear bond strength to the dentin of permanent teeth and failure site of Dentastic hydrophilic dentin bonding agent. MATERIALS AND METHODS: Forty permanent noncarious molar teeth stored in distilled water were obtained. The teeth were cleaned with pumice and a rubber cup. The mesio-buccal surface of the teeth was ground flat with hand pressure with a series of SiC paper ending with the 600 grit to provide a uniform surface on dentin to which the resin composite could be applied. After preparing the tooth surface, the teeth were stored in distilled water for 48 hours. They were then divided at random into four groups of 10 specimens each: Group 1: Dentastic, five coats of primer; Group 2: Dentastic, three coats of primer; Group 3: Dentastic, five coats of primer, light-cured adhesive before resin bonding; Group 4: Dentastic, three coats of primer, light-cured adhesive before resin bonding. All specimens were thermocycled (500x) and sheared in a testing machine. After shear testing, the debonded sites of all samples were examined with a stereomicroscope and a scanning electron microscope. RESULTS: The results in MPa were: Group 1: 22.63 +/- 6.24; Group 2: 23.35 +/- 5.14; Group 3: 23.58 +/- 5.66; Group 4: 27.26 +/- 8.22. ANOVA and Student-Newman-Keuls showed no statistically significant difference between the groups. In all groups, all specimens failed at the dentin (dentin cohesive failure = dentin fracture) or at the resin (resin cohesive failure = resin fracture). This means that the bond strength of the product is stronger than the cohesive strengths of the dentin and the resin.     

Bonding of amalgam to composite: tensile strength and morphology study

OBJECTIVES: The present study was based on the premise that it may be possible to produce useful dental restorations by bonding freshly triturated amalgam to a cured composite restoration (Group 1 specimens), or by bonding uncured composite to hardened amalgam (Group 2 specimens). METHODS: To determine the validity of this premise, a phosphonate adhesive resin cement was used to produce simulated, layered dental restorations for each test group. RESULTS: The mean tensile bond strength of 24 hour-old Group 1 specimens (6.74 MPa +/- 1.63 MPa) was almost twice that of 24 hour-old Group 2 specimens. Cohesive failure of the amalgam-substrate layer was a prominent feature of the fracture pattern of Group 1 specimens. On the other hand, rupture of all Group 2 specimens occurred mainly along the adhesive-amalgam interface. Findings from SEM examination of the layers of amalgam, adhesive cement, and resin composite of intact Group 1 specimens suggested that inclusions of adhesive resin cement may be the cause of the persistent cohesive failure of the amalgam layer. SIGNIFICANCE: It may be possible to improve the strength of bonded couples made from freshly triturated amalgam and cured resin composite by minimizing the thickness of the adhesive layer.     

Effects of N-methacryloyl amino acid applications on hybrid layer formation at the interface of intertubular dentin

To understand the role of NMAA in the bonding of composite resin to a dentin surface, we investigated the effects of N-methacryloyl amino acid (NMAA) application on the expansion of aggregated collagen fibers, formation of a hybrid layer, and the tensile bond strength between composite resin and dentin. Four NMAA derivatives--N-methacryloyl-alpha-glycine (NMGly), N-methacryloyl-gamma-amino n-butyric acid (NMBu), N-methacryloyl-alpha-hydroxyproline (NMHPro), and N-methacryloyl-alpha-glutamic acid (NMGlu)--were prepared and applied to dentin surfaces which had been etched with 40% by mass H3PO4 and air-blown. The shrunken collagenous layer expanded by approximately 50% to 70% by volume of the original collagenous layer thickness after application of the NMAA primers. Application of the bonding agent and composite resin after NMAA treatment resulted in the formation of a hybrid layer. The thickness of the hybrid layer was somewhat smaller than the collagenous layer formed by the NMAA treatment only, regardless of the type of NMAA used. The thickness of the hybrid layer was approximately ten times larger than that formed without NMAA treatment. Although all NMAA primers formed hybrid layers of similar thickness, higher tensile bond strengths, from 13 to 15 MPa, were obtained when etched and air-blown dentin was treated with NMBu, NMGly, or NMGlu. NMHPro gave only 6.6 MPa, a value similar to that obtained when no NMAA was used. We concluded, therefore, that formation of the hybrid layer is a necessary but insufficient condition for high bond strength.     

Adhesion of a compomer to dental structures

The objective of this study was to evaluate the bond strength of a compomer to dental enamel, dentin, and cementum. Flat surfaces of these tissues were obtained from recently extracted human teeth. The different substrates were either treated with PSA (a primer and adhesive) or acid etched (35% phosphoric acid gel) and treated with PSA. Cylindrical specimens of compomer were then bonded to the substrates. Shear bond strength was determined after a 24-hour immersion in 37 degrees C water. Significant differences were found between both treatments on enamel, while none were found on dentin or cementum. The use of acid etchant on enamel as a surface-conditioning step previous to priming with PSA allowed a better bond between Dyract compomer and that substrate; acid etching was not particularly needed on dentin and cementum.     

The effect of microetching on the bond strength of metal brackets when bonded to previously bonded teeth: an in vitro study

The purpose of this in vitro study was to answer the following questions for three different metal brackets: (1) when rebonding a previously bonded tooth, how do shear bond strengths compare for new brackets, new microetched brackets, and debonded microetcher cleaned brackets? and (2) how do the different bracket types compare with respect to the time required to remove composite resin from their bonding pads with a microetcher? Ninety human premolars and canines previously debonded of metal brackets were randomly assigned to 9 groups of 10 teeth each. New, new etched, and debonded etched cleaned brackets of each type were bonded with composite resin onto teeth, and the bonds tested to failure for shear bond strength. An analysis of variance and Duncan's multiple range test were used to compare bracket/enamel bond strength. Within each bracket type no significant differences were found between mean bond strengths for new, new etched, and debonded etched conditions, a finding that supports the use of microetching to clean accidentally debonded brackets. Mean times for removal of resin from bonding pads with a microetcher varied from 9.3 seconds to 11.9 seconds, with bracket (M) requiring significantly less time for removal of resin.     

Accelerated evolution and molecular surface of venom phospholipase A2 enzymes

The objective of this study was to determine the in vitro shear bond strength (in megapascals) and location of bond failure with two light-cured glass ionomer resin systems. One system was a hybrid glass ionomer cement with resin (GC Orthodontics, Aslip, Ill), and the other system a glass-filled resin system (Reliance Orthodontic Products, Inc, Itasca, Ill). These systems, Fuji Ortho LC (GC Orthodontics) and Ultra Band Lok (Reliance), respectively, were compared to a light-cured composite resin. Maxillary premolar brackets (n = 200) were bonded to the facial surface of human premolar teeth. The two glass ionomer resin systems were each evaluated by two protocols, one according to the manufacturers' direction plus a variation of their respective technique. The five distinct groups (n = 40) were stored in 37 degreesC distilled water for 30 days and subjected to thermocycling before shear bond strength testing. The findings indicated that large variations existed between the bond strengths of the materials tested. The laboratory shear bond strength of the glass-filled resin glass ionomer cement (Reliance), whether tested in a dry or moist field, was similar to the composite control with all of the previous materials being significantly (P <.01) higher than both the hybrid glass ionomer cement groups (Fuji Ortho LC). However, the hybrid glass ionomer cement with enamel conditioner demonstrated a clinically acceptable mean megapascal value. The Adhesive Remnant Index values ranged from 0.53 to 1.62. The hybrid glass ionomer cement without enamel conditioning recorded the lowest mean adhesive remnant index score and the lowest mean megapascal score. Although both products are glass ionomer resin systems, their individual chemistries vary; this affects their clinical performance. Clinically, it may be suggested that glass ionomers used in a dry field may be beneficial for orthodontic bonding, and that glass ionomer resin systems used in a moist environment need an enamel conditioner.     

In vitro bonding of adhesive resin to dental alloys and dentine

The purpose of this in vitro investigation was to compare the shear bond strength of sandblasted, tin-plated and metal primed Type II gold alloy bonded to Ni-Cr alloy, as well as sandblasted Type II gold bonded to dentine, using two different adhesive resin cements. All bonding surfaces were treated with C&B-Metabond (Parkell, CB) or Imperva Dual (Shofu, ID), according to the manufacturers' instructions. In all, 20 sandblasted, 20 tin-plated and 20 metal-primed gold cylinders were bonded to Ni-Cr, and 20 sandblasted gold cylinders bonded to dentine. Bonds were stressed to failure using a shear load in an Instron testing machine. Data were calculated, statistically analysed (ANOVA and Student-t-test), and the fracture sites examined in a SEM. The CB and ID systems demonstrated significantly higher bond strengths (p < 0.01) when the gold was tin-plated, but CB demonstrated significantly lower bond strengths (p < 0.01) when the gold was pre-treated with metal primer. CB always demonstrated significantly higher metal (p < 0.01) and dentine (p < 0.05) bond strengths than ID.     

Body composition in systemic lupus erythematosus

Bovine enamel is commonly used in enamel bonding studies, therefore, a familiarity with some aspects of bovine enamel bonding are important in order to evaluate the studies. Bovine enamel has the advantages of easy attainability and similar microstructure to human enamel. In this study the strength of the enamel bond using an orthodontic adhesive was compared between deciduous bovine, permanent bovine, and human enamel, as well as, the effect on bond strength of multiple rebonding to bovine enamel. This study found that the bond strength to bovine enamel was 21% to 44% weaker than to human enamel, and the bond strength to deciduous bovine enamel was significantly greater than to permanent bovine enamel. Either all deciduous or all permanent bovine incisors should be used, or permanent and deciduous bovine incisors evenly distributed in sample groups. Bovine enamel was rebonded five times without significantly affecting bond strength, thus, bovine enamel can be reused in bonding studies without significantly affecting the results.     

Comparing the tensile strength of brackets adhered to laser-etched enamel vs. acid-etched enamel

This study compared the tensile bond strength of brackets adhered to laser-etched enamel with that of brackets adhered to acid-etched enamel. Forty extracted, intact bovine teeth were treated with either 37 percent phosphoric acid for 15 seconds or neodymium:yttrium-aluminumgarnet laser on black-ink-coated enamel. After thermocycling, tensile stress was applied to the bonded specimens at a 0.1 millimeter/minute orosshead speed. A t-test comparison of means showed a significant difference between the laser-etched and acid-etched teeth, with the acid-etched teeth demonstrating significantly more tensile bond strength at a 95 percent level of significance.     

The effect of eugenol containing and non-eugenol temporary cements on the resin-enamel bond

This study was undertaken to compare the effect of eugenol containing and non-eugenol temporary cements on the bond strength of three brands of luting cements to enamel. Flat enamel surfaces were prepared on 90 surgically removed, unerupted, human third molar teeth. The teeth were randomly divided into three groups of thirty. The flat enamel surfaces in two of the groups were treated with either a eugenol containing or non-eugenol temporary cement and the third group was left untreated. The teeth were stored in water for 7 days and the cements then removed and all surfaces etched. The teeth were divided into 9 sub-groups of 10 each and one of the three resin cements was then bonded to each sub-group. The relevant shear bond strengths were determined after 7 days. The results indicated that prior use of a eugenol containing temporary cement reduced the resin cement-enamel bond strengths. No differences were found between the bonds achieved by the three brands. It was concluded that eugenol containing temporary cements should not be used prior to bonding with resin luting cements.