Influence of preliminary etching on the stability of bonds created by one-step self-etch bonding systems

We evaluated the effects of preliminary etching of dentine on the stability of the bond created by one-step self-etch adhesives under different storage conditions. Adper Easy Bond (3M ESPE) and iBond Self-Etch (iBond SE; Heraeus Kulzer) were applied with an etch-and-rinse (i.e. after preliminary phosphoric acid etching for 15 s) or a self-etch approach. Resin-dentine bonded specimens were sectioned perpendicularly to the adhesive interface according to the 'non-trimming technique'. Beams were stored in artificial saliva for 24 h, 6 months, or 1 yr at 37°C, or in 10% NaOCl for 5 h at room temperature, and then stressed until failure; the microtensile bond strengths were calculated. Interfacial nanoleakage of additional teeth was evaluated using light microscopy or transmission electron microscopy. Adper Easy Bond showed higher bond strength than iBond SE, regardless of the dentine treatment. Similar microtensile bond strength results were obtained for teeth subjected to artificial ageing in 10% NaOCl for 5 h at room temperature and for teeth stored in artificial saliva for 6 months at 37°C. The additional etching step increased the microtensile bond strength for Adper Easy Bond and iBond SE. This study supports the use of one-step adhesives on etched dentine because of the increased bond strength compared with their application onto smear-layer-covered dentine, regardless of storage conditions.     

Influence of ageing on self‐etch adhesives: one‐step vs. two‐step systems

The aim of this study was to evaluate microtensile bond strength (μTBS) to dentine, interfacial nanoleakage expression, and stability after ageing, of two‐step vs. one‐step self‐etch adhesives. Human molars were cut to expose middle/deep dentine, assigned to groups (n = 15), and treated with the following bonding systems: (i) Optibond XTR (a two‐step self‐etch adhesive; Kerr), (ii) Clearfil SE Bond (a two‐step self‐etch adhesive; Kuraray), (iii) Adper Easy Bond (a one‐step self‐etch adhesive; 3M ESPE), and (iv) Bond Force (a one‐step self‐etch adhesive; Tokuyama). Specimens were processed for μTBS testing after 24 h, 6 months, or 1 yr of storage in artificial saliva at 37°C. Nanoleakage expression was examined in similarly processed additional specimens. At baseline the μTBS results ranked in the following order: Adper Easy Bond = Optibond XTR ≥Clearfil SE = Bond Force, and interfacial nanoleakage analysis showed Clearfil SE Bond = Adper Easy Bond = Optibond XTR> Bond Force. After 1 yr of storage, Optibond XTR, Clearfil SE Bond, and Adper Easy Bond showed higher μTBS and lower interfacial nanoleakage expression compared with Bond Force. In conclusion, immediate bond strength, nanoleakage expression, and stability over time were not related to the number of steps of the bonding systems, but to their chemical formulations.     

aggressiveness of contemporary self-etching adhesives part ii. etching effects on unground enamel

Objective : The purpose of this study was to investigate the etching efficacy of three self‐etching primers on unground enamel by (1) examining the etched surface using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) and (2) evaluating the microtensile bond strengths of these self‐etching primers to unground enamel using either their manufacturers' adhesive or a control resin. Materials and Methods : Three self‐etching systems were evaluated in this study: Clearfil® SE Bond (Kuraray Co. Ltd, Osaka, Japan), Non‐Rinse Conditioner® (NRC; Dentsply DeTrey, Konstanz, Germany), and Prompt L‐Pop® (ESPE, Seefeld, Germany). All‐Bond® 2 (Bisco Inc., Schaumburg, IL, USA), a total‐etch adhesive system, was used as a control. Buccal surfaces of human bicuspids were conditioned using either a self‐etching primer or 32% phosphoric acid for SEM examination of the conditioned enamel. The self‐etching materials were rinsed with an ascending series of ethanol. For TEM examination, each adhesive system was used according to its manufacturer's instructions. Unground enamel treated with NRC was bonded using Prime & Bond NT® (Dentsply DeTrey). Uninfiltrated enamel was then completely dissolved, and resininfiltrated replicas were assessed for the extent of penetration of the adhesives into the enamel. For microtensile bond strength evaluation, specimens were assigned to two groups. The first group was conditioned and bonded according to each manufacturer's instructions. In the second group the conditioned enamel surfaces were rinsed with ethanol to remove the self‐etch primer and then were primed and bonded using the control primer and resin adhesive. Resin composite (Z100®, 3M ESPE, St. Paul, MN, USA) was applied in 2 mm increments. The first resin composite increment was light‐cured using the pulse delay technique, followed by conventional light‐activation of subsequent increments. Specimens were sectioned into uniform 0.96 mm² beams and were subjected to tensile stress until failure. Results : The etching pattern and the subsurface hybrid layer morphology revealed by SEM and TEM varied by system. Clearfil SE Bond had the mildest etching pattern, whereas Prompt L‐Pop had an etching pattern similar to that of 32% phosphoric acid. When adhesive systems were used as directed, the mean microtensile bond strengths of the three self‐etching adhesive systems were not significantly different from one another, but they were significantly lower than that of the control group (10–14 MPa vs 27 MPa). When bonding specimens with the control adhesive resin, the mean microtensile bond strengths of NRC with Prime & Bond NT and Prompt L‐Pop were not significantly different from those of the control group, but all were significantly higher than that of Clearfil Mega SE Bond. Conclusions : The self‐etching primers evaluated in this study had significantly lower microtensile bond strengths to unground enamel than did a total‐etch system. There was no relationship between the etching efficacy of the adhesive systems and the microtensile bond strength.     

Effects of thermocycling and use of ElectroBond on microtensile strength and nanoleakage using commercial one‐step self‐etch adhesives

The aim of this study was to determine the effect of thermocycling and the use of an electronically assisted application technique on the microtensile bond strength and nanoleakage of bonded interfaces created using one‐step self‐etch adhesives. Composite build‐ups were bonded coronally to sectioned human molars using XENO III or Clearfil S³Bond. Adhesives were applied following the manufacturers’ instructions (control) or with the aid of an electrical application device (ElectroBond). Teeth were sectioned into non‐trimmed bonded beams for microtensile testing. Half of the specimens were subjected to 20,000 thermocycles, and the controls were not thermocycled. All specimens were tested to failure and peak stress was calculated. Additional specimens were prepared for nanoleakage analysis using transmission electron microscopy (TEM). The immediate bond strength of both adhesives increased as a result of using the ElectroBond device (XENO III 38.9 ± 8.1 MPa; Clearfil S³Bond 46.2 ± 9.9 MPa) compared with no use of the device (XENO III 26.7 ± 7.8 MPa; Clearfil S³Bond 38.9 ± 8.1 MPa). Thermocycling significantly decreased the bond strength of XENO III (27.1 ± 7.9 MPa with the use of ElectroBond; 20.7 ± 9.2 MPa without the use of ElectroBond); however, thermocycling did not affect the Clearfil S³Bond strength (47.2 ± 8.6 MPa with the use of ElectroBond; 33.6 ± 8.3 MPa without the use of ElectroBond). Reduced nanoleakage was found for both resins as a result of the use of the ElectroBond device, with or without thermocycling. Application of one‐step, self‐etch adhesives with the ElectroBond device significantly increased microtensile bond strength and reduced nanoleakage, but the effect of thermocycling was found to be brand‐dependent.     

Bonding characteristics of self-etching adhesives to intact versus prepared enamel

Purpose: This study tested the null hypothesis that the preparation of the enamel surface would not affect the enamel microtensile bond strengths of self‐etching adhesive materials. Materials and Methods: Ten bovine incisors were trimmed with a diamond saw to obtain a squared enamel surface with an area of 8 × 8 mm. The specimens were randomly assigned to five adhesives: (1) ABF (Kuraray), an experimental two‐bottle self‐etching adhesive; (2) Clearfil SE Bond (Kuraray), a two‐bottle self‐etching adhesive; (3) One‐Up Bond F (Tokuyama), an all‐in‐one adhesive; (4) Prompt L‐Pop (3M ESPE), an all‐in‐one adhesive; and (5) Single Bond (3M ESPE), a two‐bottle total‐etch adhesive used as positive control. For each specimen, one half was roughened with a diamond bur for 5 seconds under water spray, whereas the other half was left unprepared. The adhesives were applied as per manufacturers' directions. A universal hybrid composite resin (Filtek Z250, 3M ESPE) was inserted in three layers of 1.5 mm each and light‐cured. Specimens were sectioned in X and Y directions to obtain bonded sticks with a cross‐sectional area of 0.8 ± 0.2 mm². Sticks were tested in tension in an Instron at a cross‐speed of 1 mm per minute. Statistical analysis was carried out with two‐way analysis of variance and Duncan's test at p <. 05. Ten extra specimens were processed for observation under a field‐emission scanning electron microscope. Results: Single Bond, the total‐etch adhesive, resulted in statistically higher microtensile bond strength than any of the other adhesives regardless of the enamel preparation (unprepared = 31.5 MPa; prepared = 34.9 MPa, not statistically different at p < 05). All the self‐etching adhesives resulted in higher microtensile bond strength when enamel was roughened than when enamel was left unprepared. However, for ABF and for Clearfil SE Bond this difference was not statistically significant at p > 05. When applied to ground enamel, mean bond strengths of Prompt L‐Pop were not statistically different from those of Clearfil SE Bond and ABF. One‐Up Bond F did not bond to unprepared enamel. Commercial self‐etching adhesives performed better on prepared enamel than on unprepared enamel. The field‐emission scanning electron microscope revealed a deep interprismatic etching pattern for the total‐etch adhesive, whereas the self‐etching systems resulted in an etching pattern ranging from absent to moderate. CLINICAL SIGNIFICANCE For the recently introduced all‐in‐one self‐etching dental adhesives, instrumentation of enamel may be critical for their ability to optimally bond to enamel.     

Adhesion to Er:YAG laser and bur prepared root and crown dentine

Background: The purpose of this study was to evaluate the bond strengths between dentine and resin composite obtained after Er:YAG laser treatment of crown or root dentine used together with self‐etch and total‐etch adhesive systems. Methods: One etch‐and‐rinse adhesive (Single Bond, 3M, USA) and one self‐etch system (Clearfil SE Bond, Kuraray, Japan) were applied to root and crown dentine prepared with a regular bur in a turbine or with an Er:YAG laser. The shear bond strength was determined after thermocycling and statistically analysed using independent t‐tests. Results: Crown sites bonded using Clearfil SE Bond and Single Bond adhesives yielded bond strengths similar to that of root dentine sites (p > 0.05). Clearfil SE Bond was stronger in both the lased and non‐lased groups (p < 0.05). The lowest bond strength was obtained when Single Bond without acid etching was used on Er:YAG ablated dentine. When total‐etch adhesive was used, there were significant differences (p < 0.05) between the laser‐ablated and laser‐ablated/acid‐etched and bur‐cut/acid‐etched groups. Conclusions: Er:YAG laser irradiation of root and crown dentine conducted prior to the adhesive protocol adversely affected adhesion and decreased bond strength compared with traditional preparation.     

Shear Bond Strengths of One-Bottle Adhesives to Oil-Contaminated Enamel

Purpose: To evaluate resin bond strength to enamel contaminated with handpiece oil. Materials and Methods: Bovine teeth were randomly assigned to six groups of 20 teeth each for treatment with one of six different bonding systems (five one‐bottle and one multibottle). For each system, 10 enamel specimens were contaminated with handpiece oil before acid‐etching and 10 were contaminated after acid‐etching. The enamel was etched for 15 seconds using 35% phosphoric acid. Following adhesive application, composite resin was bonded using a gelatin capsule technique. Shear bond strengths from the two contaminated groups were compared to bond strengths to uncontaminated enamel obtained from a previous study that was performed by the same group of investigators, using the same facility, materials, and methods. Results: Two‐way analysis of variance (ANOVA) showed that the factor “surface contamination” did not have a significant effect on bond strength (p > .542). The type of adhesive and the interaction of adhesive and surface contamination were significant (p <.0001 and p <.003, respectively). When oil was applied before etching, mean bond strengths ranged from 18.0 ± 4.8 MPa for OptiBond SOLO (Kerr Corp., Orange, California) to 25.3 ± 5.6 MPa for Tenure Quik with Fluoride (Den‐Mat Corp., Santa Maria, California). With oil applied after etching, bond strengths ranged from 18.4 ± 8.0 MPa for Tenure Quik with Fluoride to 27.4 ± 5.4 MPa for Single Bond (3M Dental Products, St. Paul, Minnesota). For the same adhesive, comparing uncontaminated and “oil‐before‐etch” contaminated groups, the only statistically significant difference in bond strengths was for OptiBond SOLO: 21.8 ± 4.0 MPa (uncontaminated) versus 18.0 ± 4.8 MPa (oil before etch). Comparing uncontaminated and “oil‐after‐etch” groups, the only statistically significant difference was for Tenure: 24.5 ± 5.7 MPa (uncontaminated) and 18.4 ± 8.0 MPa (oil after etch). CLINICAL SIGNIFICANCE Surface contamination with handpiece lubricant oil does not impair appreciably the efficacy of the adhesives used in this study when bonding composite resin to enamel.     

One‐year clinical evaluation of a two‐step self‐etch adhesive with and without additional enamel etching technique in cervical lesions

Background: The aim of this study was to determine the clinical performance of a two‐step self‐etch adhesive with and without additional enamel etching technique to advanced non‐carious cervical sclerotic lesions. Methods: Twenty‐two patients (mean age = 51.5) having at least two pairs of non‐carious cervical erosion/attrition/abfraction lesions with incisal or occlusal margins in enamel and gingival margins in dentine/cementum were included in the study. The two‐step self‐etch adhesive (AdheSE; Ivoclar‐Vivadent) was either applied following the self‐etch approach on both enamel and dentine (AdheSE non‐etch), or a similar application including additional acid‐etching of the enamel cavity margins with 37% phosphoric acid (AdheSE etch). Resin composite Point 4 was used for all 104 restorations. Restorations were evaluated at baseline and at one year according to the modified United States Public Health Service (USPHS) criteria. Data were analysed by using McNemar’s test (p <0.05). Results: There were no significant differences in the marginal adaptation both at the cervical and enamel margins between AdheSE non‐etch and AdheSE etch groups (p >0.05). At one year, marginal discolouration was evident in the AdheSE non‐etch group but it was not statistically significant from the AdheSE etch group (p = 0.12). Postoperative sensitivity was 5% at baseline and reduced to 2% at one year. Conclusions: At one year, the two‐step self‐etch adhesive with and without additional enamel etching technique showed excellent clinical results to advanced non‐carious cervical sclerotic lesions.     

Enamel microhardness and bond strengths of self‐etching primer adhesives

Adebayo OA, Burrow MF, Tyas MJ, Adams GG, Collins ML. Enamel microhardness and bond strengths of self‐etching primer adhesives. Eur J Oral Sci 2010; 118: 191–196. © 2010 The Authors. Journal compilation © 2010 Eur J Oral Sci The aim of this study was to determine the relationship between enamel surface microhardness and microshear bond strength (μSBS). Buccal and lingual mid‐coronal enamel sections were prepared from 22 permanent human molars and divided into two groups, each comprising the buccal and lingual enamel from 11 teeth, to analyze two self‐etching primer adhesives (Clearfil SE Bond and Tokuyama Bond Force). One‐half of each enamel surface was tested using the Vickers hardness test with 10 indentations at 1 N and a 15‐s dwell time. A hybrid resin composite was bonded to the other half of the enamel surface with the adhesive system assigned to the group. After 24 h of water storage of specimens at 37º°C, the μSBS test was carried out on a universal testing machine at a crosshead speed of 1 mm min^?1 until bond failure occurred. The mean μSBS was regressed on the mean Vickers hardness number (VHN) using a weighted regression analysis in order to explore the relationship between enamel hardness and μSBS. The weights used were the inverse of the variance of the μSBS means. Neither separate correlation analyses for each adhesive nor combined regression analyses showed a significant correlation between the VHN and the μSBS. These results suggest that the μSBS of the self‐etch adhesive systems are not influenced by enamel surface microhardness.     

Microtensile adhesion of sealants to intact enamel

Contamination of etched enamel with saliva has been shown to result in sealant failure. Hydrophilic adhesives improve retention of sealants when enamel is contaminated. OBJECTIVE: The objective of the present study was to characterize the adhesion of two sealants to unprepared enamel etched with phosphoric acid or conditioned with the all-in-one, self-etch adhesive Adper Prompt L-Pop. METHODS: The two proximal enamel surfaces of 16 sound molars were assigned to four conditioning regimens: (1) 35% phosphoric acid for 15 s; (2) Adper Prompt L-Pop, one layer light-cured prior to sealant placement; (3) Adper Prompt L-Pop, two layers light-cured prior to sealant placement; and (4) Adper Prompt L-Pop, one layer co-cured with sealant. One of two sealants, i.e. Clinpro or Delton DDS, was applied, light-cured, followed by a composite build-up to provide support for microtensile bond testing. RESULTS: The highest mean bond strengths were obtained when Adper Prompt L-Pop was applied in two layers and light-cured prior to the insertion of Clinpro Sealant. Co-cure of Adper Prompt L-Pop with either sealant resulted in bond strengths which were not significantly different from those of the phosphoric acid control. The use of Adper Prompt L-Pop in one layer cured prior to sealant placement resulted in statistically lower bond strengths than any other application technique regardless of the sealant used. Clinpro Sealant resulted in statistically higher bond strengths than Delton DDS Sealant. CONCLUSIONS: Application of one layer of Adper Prompt L-Pop co-cured with the sealant resulted in bond strengths similar to those obtained with phosphoric acid etching.     

Influence of application method on surface free‐energy and bond strength of universal adhesive systems to enamel

The aim of the present study was to determine the influence of different adhesive application methods and etching modes on enamel bond effectiveness of universal adhesives using shear bond strength (SBS) testing and surface free‐energy (SFE) measurements. The adhesives Scotchbond Universal, All‐Bond Universal, Adhese Universal, and G‐Premio Bond were used. Prepared bovine enamel specimens were divided into four groups, based on type of adhesive, and subjected to the following surface treatments: (i) total‐etch mode with active application; (ii) total‐etch mode with inactive application; (iii) self‐etch mode with active application; and (iv) self‐etch mode with inactive application. Bonded specimens were subjected to SBS testing. The SFE of the enamel surfaces with adhesive was measured after rinsing with acetone and water. The SBS values in total‐etch mode were significantly higher than those in self‐etch mode. In total‐etch mode, significantly lower SBS values were observed with active application compared with inactive application; in contrast, in self‐etch mode there were no significant differences in SBS between active and inactive applications. A reduction in total SFE was observed for active application compared with inactive application. The interaction between etching mode and application method was statistically significant, and the application method significantly affected enamel bond strength in total‐etch mode.     

Bond strength and etching pattern of adhesive systems to enamel: effects of conditioning time and enamel preparation

ABSTRACT

Statement of the problem: The performance of self‐etch systems on enamel is controversial and seems to be dependent on the application technique and the enamel preparation. Purpose of the Study: To examine the effects of conditioning time and enamel surface preparation on bond strength and etching pattern of adhesive systems to enamel. Materials and Methods: Ninety‐six teeth were divided into 16 conditions (N = 6) in function of enamel preparation and conditioning time for bond strength test. The adhesive systems OptiBond FL (Kerr, Orange, CA, USA), OptiBond SOLO Plus (Kerr), Clearfil SE Bond (Kuraray, Osaka, Japan), and Adper Prompt L‐Pop (3M ESPE, St. Paul, MN, USA) were applied on unground or ground enamel following the manufacturers’ directions or doubling the conditioning time. Cylinders of Filtek Flow (0.5‐mm height) were applied to each bonded enamel surface using a Tygon tube (0.7 mm in diameter; Saint‐Gobain Corp., Aurora, OH, USA). After storage (24 h/37°C), the specimens were subjected to shear force (0.5 mm/min). The data were treated by a three‐way analysis of variance and Tukey's test (α = 0.05). The failure modes of the debonded interfaces and the etching pattern of adhesives were observed using scanning electron microscopy. Results: Only the main factor “adhesive” was statistically significant (p < 0.001). The lowest bond strength value was observed for OptiBond FL. The most defined etching pattern was observed for 35% phosphoric acid and for Adper Prompt L‐Pop. Mixed failures were observed for all adhesives, but OptiBond FL showed cohesive failures in resin predominantly. Conclusions: The increase in the conditioning time as well as the enamel pretreatment did not provide an increase in the resin–enamel bond strength values for the studied adhesives.

CLINICAL SIGNIFICANCE

The surface enamel preparation and the conditioning time do not affect the performance of self‐etch systems to enamel.     

Effect of a functional monomer (MDP) on the enamel bond durability of single‐step self‐etch adhesives

The present study aimed to determine the effect of the functional monomer, 10‐methacryloxydecyl dihydrogen phosphate (MDP), on the enamel bond durability of single‐step self‐etch adhesives through integrating fatigue testing and long‐term water storage. An MDP‐containing self‐etch adhesive, Clearfil Bond SE ONE (SE), and an experimental adhesive, MDP‐free (MF), which comprised the same ingredients as SE apart from MDP, were used. Shear bond strength (SBS) and shear fatigue strength (SFS) were measured with or without phosphoric acid pre‐etching. The specimens were stored in distilled water for 24 h, 6 months, or 1 yr. Although similar SBS and SFS values were obtained for SE with pre‐etching and for MF after 24 h of storage in distilled water, SE with pre‐etching showed higher SBS and SFS values than MF after storage in water for 6 months or 1 yr. Regardless of the pre‐etching procedure, SE showed higher SBS and SFS values after 6 months of storage in distilled water than after 24 h or 1 yr. To conclude, MDP might play an important role in enhancing not only bond strength but also bond durability with respect to repeated subcritical loading after long‐term water storage.     

Influence of duration of phosphoric acid pre‐etching on bond durability of universal adhesives and surface free‐energy characteristics of enamel

The purpose of this study was to evaluate the influence of duration of phosphoric acid pre‐etching on the bond durability of universal adhesives and the surface free‐energy characteristics of enamel. Three universal adhesives and extracted human molars were used. Two no‐pre‐etching groups were prepared: ground enamel; and enamel after ultrasonic cleaning with distilled water for 30 s to remove the smear layer. Four pre‐etching groups were prepared: enamel pre‐etched with phosphoric acid for 3, 5, 10, and 15 s. Shear bond strength (SBS) values of universal adhesive after no thermal cycling and after 30,000 or 60,000 thermal cycles, and surface free‐energy values of enamel surfaces, calculated from contact angle measurements, were determined. The specimens that had been pre‐etched showed significantly higher SBS and surface free‐energy values than the specimens that had not been pre‐etched, regardless of the aging condition and adhesive type. The SBS and surface free‐energy values did not increase for pre‐etching times of longer than 3 s. There were no significant differences in SBS values and surface free‐energy characteristics between the specimens with and without a smear layer. The results of this study suggest that phosphoric acid pre‐etching of enamel improves the bond durability of universal adhesives and the surface free‐energy characteristics of enamel, but these bonding properties do not increase for phosphoric acid pre‐etching times of longer than 3 s.     

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.     

Bond strengths of nonrinsing adhesives.

OBJECTIVE: The purpose of this study was to determine enamel and dentin bond strengths of a nonrinsing "all-in-one" adhesive and of a nonrinsing conditioner combined with a 1-bottle adhesive. METHOD AND MATERIALS: Specimens were obtained from 240 bovine teeth ground to expose enamel or dentin surfaces. Ten enamel and 10 dentin specimens were randomly assigned to each of 12 different combinations of adhesive system (Prompt L-Pop; no etch + Prime & Bond NT; NRC + Prime & Bond NT; 36% phosphoric acid + Prime & Bond NT; no etch + Prime & Bond 2.1; 36% phosphoric acid + Prime & Bond 2.1) and restorative material (resin composite; polyacid-modified resin composite ["compomer"]). After the application of the adhesive system, a No. 5 gelatin capsule filled with the restorative material was seated against the enamel or dentin surface. After 24 hours in distilled water at 37 degrees C, the specimens were thermocycled and the shear bond strengths were measured. RESULTS: For resin composite, etching with phosphoric acid resulted in the highest bond strengths to enamel. For compomer, the highest enamel bond strengths were achieved with both phosphoric acid and Prompt L-Pop. Treating dentin with Prime & Bond NT without etching provided the highest mean bond strength for composite. For compomer, treating dentin with Prime & Bond NT resulted in the highest mean bond strengths, regardless of the conditioner. CONCLUSION: Compomer and resin composite exhibited statistically similar bond strengths. Bond strengths to dentin were significantly lower than those to enamel.     

In vitro bonding performance of self-etch adhesives: II--ultramorphological evaluation

OBJECTIVE: To study the interfacial ultra-morphology formed by "all-in-one" self-etch adhesives. METHODS: Forty-nine extracted molars were assigned to one of five all-in-one adhesives: Adper Prompt L-Pop (AP, 3M ESPE); Clearfil S3 Bond (S3, Kuraray); G-Bond (GB, GC America); iBond (iB, Heraeus Kulzer) and Xeno IV (XE, Dentsply Caulk). Adper Single Bond Plus (SB, 3M ESPE), a two-step etch&rinse adhesive, and Clearfil SE Bond (SE, Kuraray), a two-step self-etch adhesive, were used as controls. Dentin, unground enamel and ground enamel were used as bonding substrates. Dentin specimens were processed for FESEM and TEM analyses. Enamel specimens were processed for FESEM. RESULTS: Dentin: GB, iB, S3, SE and XE resulted in a submicron-thick hybrid layer (0.2-0.7 microm), but only S3 and SE did not result in interfacial gaps. AP resulted in the thickest hybrid layer (1.7-2.9 microm) among the self-etch adhesives. SB resulted in a 3.4-5.2 pm thick hybrid layer. Unground enamel-GB, iB and SE resulted in a mostly featureless morphology resembling that of untreated enamel with areas in which the superficial enamel layer was removed without dissolving the subsurface enamel. XE resulted in areas of intra-prismatic etching and areas without any etching pattern. S3 resulted in frequent shallow intra-prismatic etching, while AP was able to unveil the enamel crystallites across the entire enamel surface. Phosphoric acid in SB resulted in the deepest intra- and inter-prismatic demineralization. Ground enamel--AP resulted in a well-defined inter-prismatic etching pattern. iB, GB, SE and S3 resulted in islands of superficially dissolved enamel within areas without evidence of enamel dissolution. XE resulted in etched enamel areas with mild intraprismatic exposure of crystallites. Phosphoric acid in SB resulted in deep enamel etching. CONCLUSIONS: Only AP, an aggressive self-etch adhesive, showed enamel morphological features that resemble those created by etch & rinse adhesives. S3 and SE were the only self-etch adhesives that did not result in dentin interfacial debonding.     

Influence of acid etching and enamel beveling on the 6-month clinical performance of a self-etch dentin adhesive

This study tested the hypothesis that beveling and/or etching enamel does not affect the 6-month clinical performance of the self-etch adhesive Clearfil SE Bond in class V noncarious lesions. With Institutional Review Board approval, 34 patients were enrolled in this study. A total of 120 noncarious cervical lesions were selected and assigned to 4 groups: (1) Clearfil SE Bond was applied without any cavity preparation; (2) After the enamel was beveled, Clearfil SE Bond was applied; (3) After the enamel was etched for 15 seconds with 35% phosphoric acid, Clearfil SE Bond was applied; (4) After the enamel was beveled and etched with 35% phosphoric acid for 15 seconds, Clearfil SE Bond was applied. A microfilled composite resin was used for all restorations. Six months after initial placement, 120 restorations (a 100% recall rate) were re-evaluated. Retention rates at 6 months were 100% for all groups. Sensitivity to air improved from baseline to 6 months, but the overall difference was not statistically significant. The 6-month retention rate of the self etch dentin adhesive system Clearfil SE Bond was not improved by enamel beveling or by enamel etching. For the self-etch material Clearfil SE Bond, instrumentation or etching of enamel may not be critical for its clinical performance at 6 months.     

Microshear bond strength of resin composite to teeth affected by molar hypomineralization using 2 adhesive systems

PURPOSE: When restoring hypomineralized first permanent molars, placement of cavo-surface margins can be difficult to ascertain due to uncertainty of the bonding capability of the tooth surface. The purpose of this study was to investigate the adhesion of resin composite bonded to control and hypomineralized enamel with an all-etch single-bottle adhesive or self-etching primer adhesive. METHODS: Specimens of control enamel (N=44) and hypomineralized enamel (N=45) had a 0.975-mm diameter composite rod (Filtek Supreme Universal Restorative) bonded with either 3M ESPE Single Bond or Clearfil SE Bond following manufacturers' instructions. Specimens were stressed in shear at 1 mm/min to failure (microshear bond strength). Etched enamel surfaces and enamel-adhesive interfaces were examined under scanning electron microscopy. RESULTS: The microshear bond strength (MPa) of resin composite bonded to hypomineralized enamel was significantly lower than for control enamel (3M ESPE Single Bond=7.08 +/- 4.90 vs 16.27 +/- 10.04; Clearfil SE Bond=10.39 +/- 7.56 vs 19.63 +/- 7.42; P=.001). Fractures were predominantly adhesive in control enamel and cohesive in hypomineralized enamel. Scotchbond etchant produced deep interprismatic and intercrystal porosity in control enamel and shallow etch patterns with minimal intercrystal porosity in hypomineralized enamel. Control enamel appeared almost unaffected by SE Primer; hypomineralized enamel showed shallow etching. The hypomineralized enamel-adhesive interface was porous with cracks in the enamel. The control enamel-adhesive interface displayed a hybrid layer of even thickness. CONCLUSIONS: The microshear bond strength of resin composite bonded to hypomineralized enamel was significantly lower than for control enamel. This was supported by differences seen in etch patterns and at the enamel-adhesive interface.     

Effects of a self-etching primer and 37% phosphoric Acid etching on enamel: a scanning electron microscopic study

Objective: The purpose of this study was to compare the etching effects of a self-etching primer with 37% phosphoric acid on enamel by using a scanning electron microscope. Bond strength and the site of bond failure were also determined for brackets bonded using SEP and 37% phosphoric acid. Materials and methods: A total of 60 maxillary premolar teeth were used for this study and they were divided into four groups. First two groups were used for studying the different types of etch patterns obtained and the next two groups were used to test the bond strength with the help of Universal testing machine. After debonding, the amount of residual adhesive was assessed according to adhesive remnant index using a stereomicroscope. Results: The majority of etch patterns obtained in the 37% phosphoric acid group were type II, whereas in the SEP group, type IV pattern was more common. There was no statistically significant difference between mean bond strengths obtained with the SEP group and the phosphoric acid group. Use of SEP results in less amount of residual adhesive on tooth surface after debonding. Conclusion: SEP produces more conservative etch pattern compared to 37% phosphoric acid. Use of SEP for bonding provides similar and clinically acceptable bond strength compared to use of 37% phosphoric acid etching technique and requires less clean-up procedures hence, reduces enamel loss. Clinical significance: Use of 37% phosphoric acid for orthodontic bonding yields high bond strength but, causes enamel loss during both etching and debonding. SEPs not only provide adequate bond strength with a more conservative etch pattern but also enable easy debonding, thereby reducing the enamel damage. Keywords: Etch pattern, Enamel, SEM, Self-etching primer. How to cite this article: Nanjannawar LG, Nanjannawar GS. Effects of A Self-Etching Primer and 37% Phosphoric Acid Etching on Enamel: A Scanning Electron Microscopic Study. J Contemp Dent Pract 2012;13(3):280-284. Source of support: Nil Conflict of interest: None declared.