Bond strength of a mild self-etch adhesive with and without prior acid-etching

SUMMARY: The self-etch approach provides dentists with a generation of user-friendly and less technique-sensitive adhesives. Nevertheless, some concern has been raised regarding their bonding effectiveness to enamel, in particular when so-called 'mild' self-etch adhesives are employed. OBJECTIVES: The purpose of this study was to test the hypothesis that the two-step self-etch adhesive Clearfil SE Bond (C-SE; Kuraray, Osaka, Japan) bonds equally effective to enamel/dentin either with or without prior etching with phosphoric acid. METHODS: Bur-cut enamel/dentin surfaces prepared from human molars were partially split in two halves by cutting a shallow groove. One half was first etched with 40% phosphoric acid (K-etchant), while protecting the other half by holding a razor blade in the groove. Next, C-SE was applied strictly following the manufacturer's instructions, after which the surface was built up using Z100 (3M Espe). After 24-h water storage, micro-specimens were prepared with the interface circularly constricted using a Micro-Specimen Former, prior to micro-tensile bond strength (MPa) measurement. In addition, interfaces of C-SE with enamel/dentin prepared with and without beforehand acid etching were examined by Feg-SEM and TEM. RESULTS: Beforehand etching significantly increased the bonding effectiveness of C-SE to enamel. A clearly more micro-retentive surface was revealed by TEM and Feg-SEM when enamel was etched. Phosphoric-acid etching prior to C-SE application on dentin significantly decreased the muTBS to dentin. TEM provided indications of a low-quality hybrid layer after beforehand phosphoric-acid etching. CONCLUSION: Using C-SE, additional etching with phosphoric acid to improve bonding effectiveness should be limited to enamel.     

Treated enamel surface patterns associated with five orthodontic adhesive systems--surface morphology and shear bond strength

The chief aim of this study was to evaluate the influence of three different types of pretreatment solutions (phosphoric acid, self-etching primers, and polyacrylic acid) on enamel surfaced when used in association with one of the five orthodontic adhesive systems. In the same vein, the shear bond strength of orthodontic metal brackets was also measured to evaluate the influence of bonding procedure. After the enamel surfaces of extracted human maxillary incisors were pretreated with the five adhesive systems, scanning electron microscopy (SEM) was used to observe the effects of pretreatment on enamel. Additionally, the shear bond strength of metal brackets bonded with the five adhesives was measured (n=6). SEM observation revealed different etching patterns on the enamel surface after pretreatment. As for shear bond strength, no statistically significant differences were observed among the five different adhesives (p>0.05). It was found that self-etching primers and polyacrylic acid produced a less aggressive etching pattern than phosphoric acid. Nonetheless, all the five adhesive systems provided acceptable bond strength and attachment of orthodontic brackets.     

Effect of phosphoric acid etching on the shear bond strength of two self-etch adhesives

Objective:

To evaluate the effect of optional phosphoric acid etching on the shear bond strength (SBS) of two self-etch adhesives to enamel and dentin.

Material and Methods:

Ninety-six bovine mandibular incisors were ground flat to obtain enamel and dentin substrates. A two-step self-etch adhesive (FL-Bond II) and a one-step self-etch adhesive (BeautiBond) were applied with and without a preliminary acid etching to both the enamel and dentin. The specimens were equally and randomly assigned to 4 groups per substrate (n=12) as follows: FL-Bond II etched; FL-Bond II un-etched; BeautiBond etched; BeautiBond un-etched. Composite cylinders (Filtek Z100) were bonded onto the treated tooth structure. The shear bond strength was evaluated after 24 hours of storage (37ºC, 100% humidity) with a testing machine (Ultra-tester) at a speed of 1 mm/min. The data was analyzed using a two-way ANOVA and post-hoc Tukey''s test with a significance level of p<0.05. A field emission scanning electron microscope was used for the failure mode analysis.

Results:

Both adhesives evidenced a significant decrease in the dentin SBS with the use of an optional phosphoric acid-etching step (p<0.05). Preliminary phosphoric acid etching yielded significantly higher enamel SBS for FL-Bond II (p<0.05) only, but not for BeautiBond. FL-Bond II applied to un-etched dentin demonstrated the highest mean bond strength (37.7±3.2 MPa) and BeautiBond applied to etched dentin showed the lowest mean bond strength (18.3±6.7 MPa) among all tested groups (p<0.05).

Conclusion:

The use of a preliminary acid-etching step with 37.5% phosphoric acid had a significant adverse effect on the dentin bond strength of the self-etch adhesives evaluated while providing improvement on the enamel bond strength only for FL-Bond II. This suggests that the potential benefit that may be derived from an additional etching step with phosphoric acid does not justify the risk of adversely affecting the bond strength to dentin.     

In vitro testing of all-in-one adhesives as fissure sealants

PURPOSE: To evaluate the clinical efficacy of all-in-one adhesives as fissure sealants. METHODS: Resin-enamel bonded specimens were fabricated between polished and ground enamel surfaces using two all-in-one adhesives (One-Up Bond F and Xeno CF Bond) and two resin sealants (Teethmate F-1 and Helioseal F). Specimen beams were prepared and microtensile bond tests were performed at a crosshead speed of 1 mm/minute. The bond strengths obtained were subjected to one-way ANOVA and Scheffe's F test (P < 0.05: n=12 for each group). To evaluate the etching effect of phosphoric acid and the all-in-one adhesives, the treated enamel surfaces (37% phosphoric acid, 40% phosphoric acid, or all-in-one adhesives) were examined by FE-SEM. RESULTS: The bond strengths of the two all-in-one adhesives tested to the polished enamel surface were significantly lower (P < 0.05) than to ground enamel. However, no significant differences (P > 0.05) were found between the polished and ground enamel surfaces for resin sealants using phosphoric acid. Under SEM examination, 37% or 40% phosphoric acid etched the enamel surface more than all-in-one adhesives.     

Efficacy of using self-etching primer with a 4-META/MMA-TBB resin cement in bonding orthodontic brackets to human enamel and effect of saliva contamination on shear bond strength

The objective of this study was (1) to evaluate the effectiveness of Megabond when used with Superbond C&B, a 4-methacryloloxyethyl trimellitate anhydride (4-META)/methyl methacrylate (MMA)-tri-n-butyl borane (TBB) resin, to bond orthodontic metal brackets to human enamel and (2) to examine the influence of saliva contamination on shear bond strength. Metal brackets were bonded to phosphoric acid-etched or Megabond-treated human premolars using Superbond C&B resin cement. The effects of saliva contamination after acid etching or self-etch priming, and the effect of re-etching or self-etch priming after saliva contamination on shear bond strength were also assessed. The shear bond strengths were measured after immersion in water at 37 degrees C for 24 hours. Data were analyzed using two-way analysis of variance and Fisher's protected least significant difference test for multiple comparisons. There were no significant differences in shear bond strength between phosphoric acid etching and self-etch priming for no contamination, saliva contamination, and repeat treatment (etching or priming) after saliva contamination. With phosphoric acid etching, saliva contamination significantly decreased the shear bond strength. Repeat phosphoric acid etching after saliva contamination did not significantly improve the bond strengths. With self-etching primer treatment, however, saliva contamination did not cause any decrease of bond strength. Phosphoric acid etching produced more enamel fracture than self-etching primer treatment. Field-emission scanning microscopy revealed less dissolution of enamel surface resulted from self-etching primer compared with phosphoric acid. These results suggest that Megabond when used with Superbond C&B resin cement may be a good candidate for bonding orthodontic brackets to human enamel.     

Evaluation of the enamel etching capacity of six contemporary self-etching adhesives

OBJECTIVES: The purpose of this study was to evaluate the capacity of six contemporary self-etch primers/adhesives to demineralize ground enamel by means of ultrastructural analysis of the etching surface under SEM and by spectroscopic measurement of the percentage of calcium and phosphate ions dissolved. METHODS: Seventy non-carious extracted human third molars were sub-divided into 2 groups of 35 teeth each. The teeth of the first group were ground to expose flat, polished enamel surfaces 3-4mm thick. The samples thus obtained were treated with six self-etch bonding systems and a phosphoric acid gel (control group). The self-etch priming agent was then eliminated and the etched enamel surface observed by SEM. From the teeth of the second group, disc-shaped specimens were made from ground enamel and subjected to application of each of the six self-etchants. Once the etching product had been rinsed off, the rinse solution was analyzed by atomic flame spectroscopy to evaluate the percentage of calcium and phosphate ions dissolved. RESULTS: SEM images show that AdheSE, Adper Prompt L-Pop and Xeno III, despite having a less intensive etching efficacy than phosphoric acid, gave a regular pattern over a considerable surface area and depth. iBond and One-Up Bond F gave less regular demineralization. For Clearfil SE Bond, the demineralization was ineffective. Results of the percentage of mineral loss show that Adper Prompt L-Pop and Xeno III were the most efficient self-etch products. AdheSE, iBond and One-Up Bond F, respectively exhibited decreasing demineralizing capacity. Clearfil SE Bond, however, gave low proportions of calcium and phosphate ions loss and was considered unsatisfactory. CONCLUSION: The action on enamel was not the same for all self-etch systems tested. The etching potential of the self-etch adhesives was lower than that of phosphoric acid but some self-etch systems, particularly those with monomers containing phosphate derivatives, gave results close to those obtained with phosphoric acid.     

Effects of phosphoric acid pretreatment and substitution of bonding resin on bonding effectiveness of self-etching systems to enamel

PURPOSE: To examine the etching efficacy of three self-etching systems to unconditioned enamel and to phosphoric-acid conditioned enamel using scanning electron microscopy (SEM), and to investigate the microtensile bond strength (muTBS) of three self-etching adhesives to unconditioned enamel used according to the manufacturers' instructions, on phosphoric-acid conditioned enamel, and when their different adhesives were replaced with a control resin after etching. MATERIALS AND METHODS: Clearfil SE Bond (CSE), Tyrian SPE/One-Step Plus (TY), and Adper Prompt L-Pop (AD) were employed. Scotchbond Multi-Purpose Plus (SBMP), an etch-and-rinse adhesive, was used as control. For muTBS evaluation, the buccal or lingual mid-coronal enamel of 30 molars was used. In the first group, self-etching adhesives were applied conventionally, according to manufacturers' directions (group C). A second group of specimens was etched with 35% phosphoric acid before application of the self-etching adhesives (group PA), and the third group of specimens was etched with the self-etching adhesives, rinsed, but bonded using a control bonding resin (group CR). Following restoration with Z250, they were sectioned into beams (0.8 mm2), and stressed to failure. Data were subjected to two-way ANOVA and Tukey's test. The etching efficacy of the self-etching adhesives, phosphoric acid, and prior phosphoric acid + SE application was evaluated under SEM. RESULTS: All self-etching adhesives applied as recommended by the manufacturers showed lower muTBS values than those obtained in PA and CR groups, although this difference was only significant for TY and AD. The means of all self-etching adhesives under PA and CR groups were similar to SBMP. The enamel conditioned with self-etching adhesive showed a less distinct pattern. CSE exhibited the mildest etching pattern. All self-etching adhesives applied after phosphoric acid exhibited a more retentive etching pattern. CONCLUSION: The bond strength values of low-pH self-etching adhesives can be improved by the adjunctive use of phosphoric acid or replacement of the bonding resin.     

Pit and fissure sealing. Bonding of bulk-cured, low-filled, light-curing resins to bacteria-contaminated uncut enamel in high c-factor cavities

PURPOSE: To examine the ultrastructure of bonding to occlusal enamel fissures using phosphoric acid etching in combination with a pit and fissure sealant (Clinpro Sealant), a total-etch single-bottle adhesive (One-Step) followed by the fissure sealant, and two single-step self-etch adhesives (Adper Prompt and Xeno III) followed by the fissure sealant. METHODS: Sections of bonded enamel fissures retrieved from specimens bonded in vivo were polished, and rinsed with phosphoric acid to bring surfaces into relief. They were examined, first under non-dehydrated conditions with field emission-environmental SEM, to evaluate the marginal integrity of the bonds. The same specimens were then re-examined under dehydrated conditions with conventional SEM to capture more detailed ultrastructural features. Extent of resin penetration into etched enamel was further evaluated by TEM examination of sections taken from undemineralized unstained bonded specimens. These sections were further examined after HCl demineralization and staining. RESULTS: All occlusal fissure walls examined were lined with remnant aprismatic enamel. Full penetration of resins into the bottom of the fissures, and gap-free interfaces were not observed in any of the specimens, irrespective of whether total-etch or self-etch adhesives were used with the sealant. Phosphoric acid did not penetrate well into the fissures and although hybridization of the etched aprismatic enamel was observed with or without the use of the total-etch adhesive, etching was inconsistent and gaps were frequently observed. Entrapment of bacteria within the fissure walls was frequently seen. The more aggressive self-etch adhesive Adper Prompt created etching in aprismatic enamel that approached that of phosphoric acid etching. The moderately aggressive self-etch adhesive Xeno III produced 1 mm thick hybrid layers in the aprismatic enamel fissure wall.     

Ceramic bracket bonding: a comparison of bond strength with polyacrylic acid and phosphoric acid enamel conditioning

The purpose of this study was to compare in vitro shear bond strength with three different enamel surface preparations: (1) 37% phosphoric acid etch, (2) sulfated polyacrylic acid etch with removal of crystals by vigorous rinsing and (3) polyacrylic acid etch with crystal growth. Forty extracted human premolar teeth were divided into four groups of ten. Ceramic brackets were bonded to teeth in each of three groups. The fourth group used was bonded with metal brackets and a phosphoric acid enamel preparation. The same lightly filled resin cement was used for all groups. A shearing force was applied to the teeth. The results demonstrated that the shear force needed to debond with ceramic brackets was 21% greater than the shear force with metal brackets. The polyacrylic acid crystal growth group had shear bond strength values approximately one half as great as the phosphoric acid etch group when ceramic brackets were used. Bond failures in the phosphoric acid etch group were at the bracket/resin interface with the bulk of the resin remaining on the tooth compared with the polyacrylic acid crystal growth group in which the bond failure was at the enamel resin interface. Enamel fractures were not found when healthy nonrestored teeth were subjected to the shearing force. In a preliminary test using phosphoric acid etch and teeth with compromised enamel (large restorations involving three or more surfaces), half of the teeth fractured during debonding. The study demonstrated that a polyacrylic acid conditioning of the enamel surface produces different retentive surfaces, depending on the presence or absence of crystal growth.(ABSTRACT TRUNCATED AT 250 WORDS)     

瓷面处理对金属托槽与瓷面粘接性能的影响

目的　研究瓷表面不同处理方法对金属托槽与瓷修复体的粘接强度及去粘接后瓷面完整性的影响。方 法　根据使用粘接剂和表面处理方法的不同,将80个瓷面随机分为8组,每组10个瓷面。分别用京津釉质粘接剂 和光固化复合树脂粘接,表面处理分别行37%磷酸酸蚀、9·6%氢氟酸酸蚀、打磨去釉、瓷面涂硅烷偶联剂4种表面 处理法。试件粘接托槽后经37℃恒温水浴24 h后测定抗剪切强度,记录去粘接后的瓷面破裂情况。对磷酸酸蚀, 氢氟酸酸蚀、打磨去釉的瓷面进行扫描电镜观察。结果　采用氢氟酸酸蚀、打磨去釉、硅烷偶联剂组的粘接抗剪切 强度明显高于磷酸酸蚀组(P<0·01)。打磨去釉后用光固化复合树脂粘接及氢氟酸酸蚀或瓷表面涂硅烷处理后使 用任意一种粘接材料粘接均取得有效的粘接强度。各组去粘接后的瓷破裂率无显著性差异(P>0·05)。结论　氢 氟酸酸蚀、打磨去釉、瓷面涂硅烷偶联剂均可以明显增加金属托槽与瓷面之间的粘接抗剪切强度。瓷面涂硅烷偶 联剂是金属托槽与瓷面粘接时良好的表面处理剂。     

Tensile bond strength of one-step self-etch adhesives to Er:YAG laser-irradiated and non-irradiated enamel

This study determined the bond strengths to Er:YAG laser-irradiated and non-irradiated bovine enamel of three one-step self-etch adhesives (AQ Bond Plus (AQP), G-Bond (GB), and Clearfil Tri-S Bond (TS)) and one two-step self-etch adhesive (Clearfil Megabond (MB)). Eighty SiC paper-ground bovine enamel surfaces were used, of which half were laser-irradiated. The enamel surfaces were bonded to a resin composite with each adhesive, and tensile bond strengths were determined after 24 hours. For non-irradiated enamel groups, MB achieved greater bond strength to enamel than GB and TS (p < 0.05), but no significant difference was found between MB and AQP (p > 0.05). For laser-irradiated enamel groups, no significant differences were found among the four adhesives (p > 0.05). Additionally, for each adhesive, no significant differences were found between laser-irradiated and non-irradiated enamel. It was thus concluded that Er: YAG laser irradiation of enamel did not affect the tensile bond strength of one-step and two-step self-etch adhesives.     

In vitro shear bond strength of adhesive to normal and fluoridated enamel under various contaminated conditions.

OBJECTIVE: This study examined the shear bond strength of bonding agents to normal or fluoridated enamel following use of weak or strong acids to prepare enamel surfaces and after contamination with a measured amount of saliva at various stages of the bonding procedure. METHOD AND MATERIALS: One hundred extracted human third molar teeth were randomly separated into 2 basic groups (normal or fluoridated teeth), then divided into 5 subgroups. Group A specimens were not contaminated. After etching, enamel surfaces were dry and clean. Group B was left with wet surfaces after etching. Group C specimens were contaminated with artificial saliva and then dried. Group D specimens were contaminated with artificial saliva, rinsed, and then dried. In group E, all enamel surfaces were left contaminated with saliva after the etching procedures (with maleic acid or phosphoric acids). Adhesive resins were applied to all enamel surfaces according to the manufacturer's instructions. The specimens were then mounted and tested to determine shear bond strength. RESULTS: If normal enamel surfaces were rinsed and dried immediately after contamination, there was no significant reduction of shear bond strength of adhesive to enamel. Specimens in group E and group C had significantly lower bond strengths than did control specimens (group A). In the fluoridated groups etched with the phosphoric acid, statistically significant reductions in bond strengths were obtained in all contamination groups and in the control group. In the fluoridated specimens, there were no statistically significant differences between any of the contamination groups and the control group when maleic acid was used. CONCLUSION: Saliva contamination may not be a risk factor for successful bonding between bonding agent and dental tissues for normal or fluoridated enamel surfaces if they are rinsed and dried immediately after contamination. Etching of normal enamel surfaces with phosphoric acid in the presence of contamination may provide higher shear bond strength than etching with maleic acid.     

Self etching adhesive on intact enamel

Background and Objective: to analyze the poor performance of self-etch adhesives on intact enamel. Materials and Methods: labial surfaces of 20 caries free permanent upper central and lateral incisors were cleaned, sectioned of their roots. All specimens were mounted on acrylic block and divided randomly into two groups. In one group the application of self-etch adhesive was carried as per manufacturer's instructions, composite cylinders were built, whereas in the other group, 37% phosphoric acid was applied before the application of self-etching adhesives. Then the resin tags were analyzed using the scanning electron microscope. Results: showed that when phosphoric acid was used, there was significant increase in the depth of penetration of resin tags. Conclusion: the results indicate that out of both treatment groups, pre-etching the intact enamel with 37% phosphoric acid resulted in the formation of longer resin tags and higher depth of penetration of resin tags of the Clearfil SE bond, which might have resulted in attaining higher bond strength of the Clearfil SE bond to intact enamel.     

Fiber post adhesion to radicular dentin: The use of acid etching prior to a one-step self-etching adhesive

The aim of this study was to evaluate the bond strength of fiber posts luted with a one-step self-etching adhesive with the push-out test after phosphoric acid conditioning of the root dentin. Thirty-six single-rooted teeth were endodontically treated. Teeth were sectioned perpendicularly to the cementoenamel junction, and a 10-mm post space was prepared with a calibrated bur. Specimens were then divided into three groups according to the adhesive protocol: A, total-etch three steps; B, self-etch one step; and C, 32% phosphoric acid conditioning and self-etch one step. Fiber posts were luted with self-curing resin-based cement. Teeth were cut in 1-mm slices and pushed until failure with an Instron machine. Results were statistically analyzed with the ANOVA and Bonferroni tests (P < .05). Two additional specimens from each group were examined under the scanning electron microscope (SEM). The 32% phosphoric acid significantly influenced the push-out bond strength of fiber posts luted with self-etch adhesives (P < .05). SEM analysis showed a continuous hybrid layer with resin tags and lateral branches in groups A and C, while group B showed smear layer dissolution with poor infiltration of the tubules.     

The effect of additional etching and curing mechanism of composite resin on the dentin bond strength

PURPOSE

The aim of this study was to evaluate the effects of additional acid etching and curing mechanism (light-curing or self-curing) of a composite resin on the dentin bond strength and compatibility of one-step self-etching adhesives.

MATERIALS AND METHODS

Sixteen human permanent molars were randomly divided into eight groups according to the adhesives used (All-Bond Universal: ABU, Clearfil S3 Bond: CS3), additional acid etching (additional acid etching performed: EO, no additional acid etching performed: EX), and composite resins (Filtek Z-250: Z250, Clearfil FII New Bond: CFNB). Group 1: ABU-EO-Z250, Group 2: ABU-EO-CFNB, Group 3: ABU-EX-Z250, Group 4: ABU-EX-CFNB, Group 5: CS3-EO-Z250, Group 6: CS3-EO-CFNB, Group 7: CS3-EX-Z250, Group 8: CS3-EX-CFNB. After bonding procedures, composite resins were built up on dentin surfaces. After 24-hour water storage, the teeth were sectioned to make 10 specimens for each group. The microtensile bond strength test was performed using a microtensile testing machine. The failure mode of the fractured specimens was examined by means of an optical microscope at ×20 magnification. The data was analyzed using a one-way ANOVA and Scheffe''s post-hoc test (α=.05).

RESULTS

Additional etching groups showed significantly higher values than the no additional etching group when using All-Bond Universal. The light-cured composite resin groups showed significantly higher values than the self-cured composite resin groups in the Clearfil S3 Bond.

CONCLUSION

The additional acid etching is beneficial for the dentin bond strength when using low acidic one-step self-etch adhesives, and low acidic one-step self-etch adhesives are compatible with self-cured composite resin. The acidity of the one-step self-etch adhesives is an influencing factor in terms of the dentin bonding strength and incompatibility with a self-cured composite resin.     

Aggressiveness of self-etch adhesives on unground enamel

Manufacturers of mild self-etch adhesives advocate the adjunctive use of phosphoric acid etching when bonding to unground enamel. This study tested the null hypothesis that there is no difference between the recently introduced, more aggressive self-etch adhesives and a total-etch adhesive in bonding to unground enamel. The ultrastructure and microtensile bond strengths (microTBS) of Xeno III (Dentsply) and Simplicity (Apex Dental Materials), bonded to unground enamel, were examined after thermocycling. Clearfil SE Bond (Kuraray), a mild self-etch adhesive, was used as the negative control, and One-Step (BISCO), a total-etch adhesive bonded to phosphoric acid-etched unground enamel, was used as the positive control. Differences in the thickness of enamel hybrid layers were observed and the aggressiveness of apatite dissolution in the four adhesives.     

Shear bond strength of enamel surface treated with air-abrasive system

The aim of this study was to evaluate the shear bond strength of a composite resin to dental enamel, using three different surface treatments. Fifteen sound third molars were randomly assigned to three groups. The mesial and distal surfaces were flattened and covered using adhesive tape with a central orifice delimiting the adhesion area (7.07 mm2). Group I, the enamel surface was conditioned with 37% phosphoric acid for 15 s; group II, the surface was treated using air abrasion with aluminum oxide; group III, the enamel surface was treated using an association of air abrasion with aluminum oxide and 37% phosphoric acid. The Single Bond (3M) adhesive system was applied and a Teflon matrix was placed and filled with composite resin Z-100 (3M) and light-cured. The shear bond strength test was performed with a universal testing machine. The acid etching technique and air abrasion with aluminum oxide associated with acid etching had the highest shear bond strength values. Data were subjected to statistical analysis using ANOVA and the Turkey test, and no statistically significant difference in shear bond strength was observed between group I (12.49 +/- 2.85 MPa) and group III (12.59 +/- 2.68 MPa). In contrast, both groups had statistically better shear bond strengths compared to group II (0.29 +/- 0.56 MPa; p < 0.05). Air abrasion with aluminum oxide does not substitute acid etching. The association of these methods to obtain adequate adhesion to the substrate is necessary.     

The effect of Er,Cr:YSGG laser and air abrasion on shear bond strength of a fissure sealant to enamel

PurposeThe authors conducted an in vitro study to evaluate the shear bond strength of a fissure sealant to enamel pretreated with erbium, chromium: yttrium, scandium, gallium, garnet (Er, Cr: YSGG) laser or air abrasion followed by acid etching.MethodsThe authors sectioned extracted sound premolars mesiodistally and used the buccal and lingual surfaces for experimental analysis. They divided specimens randomly into three groups of 15 each according to the enamel surface pretreatment methods: group A, 37 percent phosphoric acid; group B, air abrasion followed by acid etching with 37 percent phosphoric acid; group C, irradiation with Er, Cr: YSGG laser followed by acid etching with 37 percent phosphoric acid. After applying a bonding system, the authors bonded cylinders of sealant to the enamel surfaces by using transparent gelatin tubes (0.7 millimeter in diameter and 1 mm in height) and then polymerized them. They stored all specimens in distilled water at 37°C for 24 hours. They tested shear bond strength by using a universal testing machine with a crosshead speed of 0.5 mm per second. The authors analyzed the data by means of one-way analysis of variance and Tukey-Kramer post hoc tests (α = .05).ResultsThe bond strength of group B specimens was statistically higher than those of group A and group C specimens (P < .05). The authors found no statistically significant differences in shear bond strength between surfaces treated with Er, Cr: YSGG laser and those treated with acid etching alone (P > .05).ConclusionPretreatment of enamel surfaces with air abrasion increased the bond strength of fissure sealant, but pretreatment with Er, Cr: YSGG laser did not increase the effectiveness of conventional acid etching of enamel in sealant bonds.     

Bond strength of self-etch adhesives to pre-etched enamel

ObjectiveBond strengths of composite resin to enamel using four self-etch adhesive (SEA) systems were compared with the bond strength of an etch-and-rinse adhesive (ERA) system, for both polished enamel and enamel pre-etched with phosphoric acid. The objective was to determine if the pre-etching would increase the bond strengths of the SEA systems to match the ERA system.MethodsTen specimens were used for each adhesive to determine 24-h resin composite to enamel shear bond strengths (SBS) to polished (4000 grit) human enamel and this was repeated for the SEA systems for enamel that was pre-etched with phosphoric acid for 15 s. SEM analysis was made to assess the degree of etching and resin penetration into enamel for each of the adhesive systems. Data were analyzed by a two factor ANOVA with a Tukey HSD post hoc test.ResultsThe SBS to polished enamel for all four SEA systems were statistically significantly lower (p < 0.05) than the ERA control, but with pre-etched enamel there were no statistically significant differences (p > 0.05) between any of the adhesive systems. All four of the SEA systems demonstrated statistically significant increases in bond strength between bonding to polished and pre-etched enamel, ranging from 27% to 86%. The results of SEM analysis showed no differences in the resin penetration patterns of any of the adhesives for enamel that was etched with phosphoric acid.SignificancePre-etching enamel may enhance the bond strength of SEA systems to values comparable with those found with ERA adhesive systems, which may improve their overall performance in clinical use.     

酸蚀液加氟对托槽抗剪切力和釉质表面氟化物沉积的影响

目的:寻找在酸蚀液中加氟的最佳浓度,在保证托槽最大抗剪切强度的条件下达到最大的防龋效果。方法:应用含不同氟浓度的酸蚀液酸蚀牙釉质后,在酸蚀粘结后的不同时期,检测托槽的抗剪切强度,并用扫描电镜观察釉质表面形态。采用SPSS10.0统计软件包对抗剪切强度结果进行统计学分析。结果:含3%氟化钠组的抗剪切强度显著低于其余各组(P<0.05),而其余各组之间无显著性差异(P>0.05)。酸蚀液处理后的牙釉质表面沉积物的数量与酸蚀后的时间和含氟化钠的浓度增加而增加,含3%氟化钠的酸蚀液组沉积物数量最多。结论:在35%磷酸液中加入2%的氟化钠既能有效防龋,又不影响托槽的粘结力。