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.     

A New Generation of Self-etching Adhesives: Comparison with Traditional Acid Etch Technique

OBJECTIVE: The aim of this study was to determine the shear bond strength (SBS), etching pattern and depth, and debonding performance of several market-leading, self-etching (SE) adhesives primarily used in restorative dentistry (iBond, Clearfil S(3) Bond, Clearfil Protect Bond, AdheSE, XenoIII), two experimental self-etching adhesives (exp. Bond 1, exp. Bond 2) and one experimental self-etching cement (SE Zement) used with and without prior phosphoric acid-etching, and to compare them to an orthodontic self-etching product (Transbond Plus SE Primer) and to traditional acid-etch technique (Transbond XT Primer, phosphoric acid) MATERIALS AND METHODS: All adhesives were applied on pumiced and embedded bovine incisors following the manufacturers' instructions. Then one bracket each (coated with Transbond XT composite) was bonded (n = 20). Transbond XT was polymerized for 20 s from the incisal and gingival sides using a halogen device positioned at a constant 5 mm from and a 45 degrees angle to the specimen. The specimens were stored in distilled water for 24 h at 37 degrees C before measuring SBS. The ARI (adhesive remnant index) for all specimens was determined from the sheared-off brackets of each. After conditioning, the surface texture was morphologically evaluated from scanning electron microscope (SEM) images, while the etching depth was determined using a confocal laser-scanning microscope (CLSM). All groups were tested for normal distribution and analyzed by applying ANOVA, Kruskal-Wallis or the t test. In addition, a Bonferroni correction was used. RESULTS: The median values of the SBS tests were: SE Zement 3.0 MPa, SE Zement preceded by phosphoric acid etching 11.2 MPa, experimental bond 1: 7.4 MPa, experimental bond 2: 5.6 MPa, iBond 8.1 MPa, Clearfil S(3) Bond 14.1 MPa, Clearfil Protect Bond 16.6 MPa, Clearfil SE Bond 15.9 MPa, AdheSE 16.0 MPa, XenoIII 16.1 MPa, Transbond SE Primer 20.7 MPa, acid-etching+Transbond XT Primer 21.0 MPa. With the exception of iBond, we observed no significant differences among the self-etching adhesives used in Restorative Dentistry or in comparison to the Transbond Plus SE Primer. No significant differences were apparent even when compared to the Transbond XT Primer after phosphoric acid-etching. Both experimental bonding agents and SE Zement without acid etching performed significantly worse than the products mentioned above, failing to demonstrate sufficient adhesive strength. SEM examination revealed less distinctive enamel-etching patterns for self-etching products than for phosphoric acid-etching. CLSM analysis revealed etching depths between 0.5 and 20 microm depending on the product. When self-etching products were used, less residual composite remained on the enamel surface than after phosphoric acid-etching. CONCLUSIONS: All the adhesives tested are suitable for bonding orthodontic brackets and to reduce the risk of enamel fracture while minimizing etching depth, which in turns means less conditioning-related enamel loss. More development is needed to improve the etching performance of both experimental bonding agents and SE Zement.     

Shear bond strength of self-etch adhesives to enamel with additional phosphoric acid etching

This study evaluated the shear bond strength of self-etch adhesives to enamel and the effect of additional phosphoric acid etching. Seventy sound human molars were randomly divided into three test groups and one control group. The enamel surfaces of the control group (n=10) were treated with Syntac Classic (SC). Each test group was subdivided into two groups (each n=10). In half of each test group, ground enamel surfaces were coated with the self-etch adhesives AdheSe (ADH), Xeno III (XE) or Futurabond NR (FNR). In the remaining half of each test group, an additional phosphoric acid etching of the enamel surface was performed prior to applying the adhesives. The shear bond strength was measured with a universal testing machine at a crosshead speed of 1 mm/minute after storing the samples in distilled water at 37 degrees C for 24 hours. Fracture modes were determined by SEM examination. For statistical analysis, one-way ANOVA and the two-sided Dunnett Test were used (p>0.05). Additional phosphoric etching significantly increased the shear bond strength of all the examined self-etch adhesives (p<0.001). The highest shear bond strength was found for FNR after phosphoric acid etching. Without phosphoric acid etching, only FNR showed no significant differences compared to the control (SC). SEM evaluations showed mostly adhesive fractures. For all the self-etch adhesives, a slight increase in mixed fractures occurred after conditioning with phosphoric acid. An additional phosphoric acid etching of enamel should be considered when using self-etch adhesives. More clinical studies are needed to evaluate the long-term success of the examined adhesives.     

The effect of thermocycling on the adhesion of self-etching adhesives on dental enamel and dentin

AIM: The aim of the present study was to investigate the effectiveness of one total-etch self-priming adhesive and two one-step self-etching adhesive systems on the adhesion of a resin composite to both dentin and enamel. The effect of thermocycling on the adhesion was also investigated. The null hypothesis tested was thermocycling would not affect bond strengths to enamel and dentin treated with self-etching adhesives or a total-etch adhesive. METHODS AND MATERIALS: Two single-step self-etching adhesives [Xeno III (XE3) and Prompt L-Pop (PP)] and one two-step total-etch adhesive system (Prime & Bond NT) (P&B NT) were used in this study. Thirty caries-free unrestored human third molars were used to make specimens of enamel and dentin. Different adhesives were applied on enamel and dentin surfaces according to the manufacturer's instructions then hybrid composite restorative material was condensed on the surface using a mold. The bonded specimens were stored in distilled water at 37 masculineC for 24 hours before being tested. Half of the bonded specimens were tested for shear bond strength without thermocycling. The other half of the test specimens were thermocycled using a thermocycling apparatus in water baths held at 5 masculineC and 55 masculineC with a dwell time of one minute each for 10,000 cycles prior to shear testing. The mean shear bond strength before and after thermocycling was calculated, and the results were subjected to two-way analysis of variance (ANOVA) and repeated measure design to show the interaction between different materials and different times. RESULTS: The results showed shear bond strength on both enamel and dentin of the total-etch adhesive and the self-etching adhesives decreased after the specimens were subjected to thermocycling. CONCLUSIONS: The null hypothesis tested "thermocycling would not affect bond strengths treated with self-etching adhesives" was rejected. Furthermore, the study revealed the following: 1. The shear bond strength to both enamel and dentin of the total-etch adhesive and the self-etching adhesives decreased after the specimens were subjected to thermocycling. 2. XE3 achieved the highest bond strength to both enamel and dentin (26.994+/-1.17 and 25.22+/-1.26, respectively). 3. XE3 showed even better bonding after thermocycling to enamel and dentin than the total-etching system or PP. 4. Although PP bonded to enamel showed lower shear bond strength value than XE3, it has durable bond strength even after thermocycling.     

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.     

Effect of using self-etching primer for bonding orthodontic brackets

Questions over the use of self-etching primers with composite resin adhesives in the bonding of orthodontic brackets remain unsolved. In addition, there are no previous reports on the efficacy of self-etching primers with resin-modified glass ionomer cements for bonding orthodontic brackets in orthodontic dentistry. The purpose of this study was to determine the shear bond strengths of orthodontic brackets bonded with one of four protocols: (1) a composite resin adhesive used with 40% phosphoric acid, (2) the same composite resin used with Megabond self-etching primer, (3) a resin-modified glass ionomer cement adhesive used with 10% polyacrylic acid enamel conditioner, and (4) the same resin-modified glass ionomer cement used with Megabond self-etching primer. The appearance of the tooth surfaces after acid etching or priming was observed with a field-emission scanning electron microscope (FE-SEM). When used with resin-modified glass ionomer cement, Megabond self-etching primer gave no significantly different shear bond strength compared with polyacrylic acid etching. But when used with composite resin adhesive, Megabond self-etching primer gave significantly lower shear bond strength than phosphoric acid etching. However, the shear bond strength of orthodontic brackets bonded with composite resin adhesive after Megabond priming was almost the same as that of brackets bonded with resin-modified glass ionomer cement after polyacrylic acid etching. FE-SEM observation revealed that Megabond self-etching primer produced less dissolution of enamel surface than did phosphoric acid and polyacrylic acid etching. Megabond self-etching primer may be a candidate for bonding orthodontic brackets using the resin-modified glass ionomer cement for minimizing the amount of enamel loss.     

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.     

Influence of environmental conditions on orthodontic bracket bonding of self-etching systems

The influence of temperature and relative humidity (RH) on the bond strength of orthodontic adhesives was investigated. Two self-etching/composite type, one acid-etching/composite type, and one acid-etching/PMMA type of adhesives were examined under different temperature and RH conditions. Orthodontic brackets were bonded to bovine enamel, and shear bond strength test was performed at a crosshead speed of 1.0 mm/min after 24-hour storage in 37 degrees C water. Data were analyzed by Tukey's HSD test. Each specimen was assigned an ARI score. All the materials tested exhibited their highest bond strength under room conditions at a range of 10.4-17.0 MPa. Conversely, when under a lower RH condition, bond strength for all the systems ranked the lowest within a range of 6.8-12.0 MPa, with bond failure at the bracket-adhesive interface. These results demonstrated that care should be exercised when using orthodontic adhesive systems in the oral environment.     

Bonding durability of using self-etching primer with 4-META/ MMA-TBB resin cement to bond orthodontic brackets

This study determines the bonding durability when a self-etching primer is used with Superbond C&B (a 4-methacryloxyethyl trimellitate anhydride/methyl methacrylate-tri-n-butyl borane resin) to bond orthodontic brackets to enamel. Thermocycling test was used to assess bonding durability. Metal brackets were bonded to the phosphoric acid-etched or Megabond self-etching primer-treated enamel surface of human premolars using Superbond C&B. The shear bond strengths were measured after immersion in water at 37 degrees C for 24 hours or after 2000 or 5000 cycles of thermocycling between 5 degrees C and 55 degrees C. Data were analyzed using 2-way analysis of variance and Fisher's protected least significant difference test for multiple comparisons. There was no significant difference in shear bond strength between phosphoric acid and Megabond self-etching primer treatment before the thermocycling test. After 2000 and 5000 thermal cycles, significant decreases in shear bond strength were observed with phosphoric acid etching. On the contrary, no significant differences in shear bond strength were observed after 2000 and 5000 thermal cycles with Megabond self-etching primer. The adhesive remnant indices were not significantly different between phosphoric acid etching and Megabond self-etching primer treatment either before or after thermal cycles. This study suggested that when used with Superbond C&B in bonding orthodontic brackets, Megabond self-etching primer is superior to phosphoric acid as an enamel preparation agent in providing durable bond strength.     

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.     

Assessing the performance of a methyl methacrylate-based resin cement with self-etching primer for bonding orthodontic brackets

Questions over the usefulness of a self-etching primer with resin adhesive in the bonding of orthodontic brackets remain unsolved. The purpose of this study was to determine the effects of using Multibond, a new methyl methacrylate (MMA)-based resin cement with self-etching primer, on the shear bond strength of orthodontic brackets compared with Superbond C&B, which is a well-known MMA-based resin cement containing phosphoric acid etching. Metal or plastic brackets were bonded to etched or self-etching primed bovine teeth using Superbond C&B or Multibond. The shear bond strengths were measured after immersion in water at 37 degrees C for 24 hours. Data were analyzed by two-way analysis of variance and Scheffe's test. The surface appearances of the teeth after phosphoric acid etching or self-etching priming were observed by field-emission scanning electron microscopy (FE-SEM). Metal brackets bonded with Multibond had a significantly lower shear bond strength than metal brackets bonded with Superbond C&B. No significant differences in shear bond strength were observed between Multibond and Superbond C&B when plastic brackets were bonded to the enamel. The shear bond strength of metal brackets bonded with Multibond was comparable with that of plastic brackets bonded with Superbond C&B. Adhesive remnant index score showed a tendency of more residual resin cement remaining on the teeth when metal brackets were bonded with Multibond. FE-SEM observation revealed less dissolution of the enamel surface resulting from treatment with Multibond self-etching primer as compared with phosphoric acid. Thus, the Multibond system may be a candidate for bonding orthodontic brackets with the advantage of minimizing enamel loss.     

Micro-shear bond strength and morphological analysis of a self-etching primer adhesive system to fluorosed enamel

PURPOSE: The aim of this study was to evaluate micro-shear bond strength and morphological analysis of a self-etching primer adhesive system to fluorosed enamel. MATERIALS AND METHODS: Extracted human molars were classified according to the severity of fluorosis using Thylstrup and Fejerskov index into four groups (TFI: 0, normal; 1-3, mild fluorosis; 3-6, moderate fluorosis; 6-7, severe fluorosis) and divided into following two sub-groups. For the first sub-group, a self-etching primer adhesive system was applied to the ground enamel surfaces and the other sub-group was conditioned with 37% phosphoric acid for 30s prior to application of the same adhesive system. Teeth were then restored with a resin composite, stored for 24h in water and micro-shear bond strengths were measured. After shear testing, the fracture modes were observed under a laser scanning microscope. Morphological study of etching patterns and adhesive interface was done under a scanning electron microscope (SEM). The data were analyzed using two-way ANOVA and Sheffe test (p=0.05). RESULTS: No statistically significant difference was there between the different degrees of fluorosis in each sub-group. However, significant difference in the bond strengths between phosphoric acid etching and self-etching was found in moderate and severe groups. The SEM observations showed at the resin-enamel interface, thick resin tag like extensions penetrated around 3.5 microm into the enamel etched with phosphoric acid, while self-etching primer created, 1 microm lamina like penetration. CONCLUSION: Severity of fluorosis affects the micro-shear bond strength of a self-etching bonding system to fluorosed enamel.     

Relationship between enamel bond fatigue durability and surface free‐energy characteristics with universal adhesives

The relationship between enamel bond fatigue durability and surface free‐energy characteristics with universal adhesives was investigated. The initial shear bond strengths and shear fatigue strengths of five universal adhesives to enamel were determined with and without phosphoric acid pre‐etching. The surface free‐energy characteristics of adhesive‐treated enamel with and without pre‐etching were also determined. The initial shear bond strength and shear fatigue strength of universal adhesive to pre‐etched enamel were higher than those to ground enamel. The initial shear bond strength and shear fatigue strength of universal adhesive to pre‐etched enamel were material dependent, unlike those to ground enamel. The surface free‐energy of the solid (γ_S) and the hydrogen‐bonding force () of universal adhesive‐treated enamel were different depending on the adhesive, regardless of the presence or absence of pre‐etching. The bond fatigue durability of universal adhesives was higher to pre‐etched enamel than to ground enamel. In addition, the bond fatigue durability to pre‐etched enamel was material dependent, unlike that to ground enamel. The surface free‐energy characteristics of universal adhesive‐treated enamel were influenced by the adhesive type, regardless of the presence or absence of pre‐etching. The surface free‐energy characteristics of universal adhesive‐treated enamel were related to the results of the bond fatigue durability.     

自酸蚀与全酸蚀粘接剂对牙釉质和牙本质的剪切粘接强度比较

目的 比较自酸蚀与伞酸蚀粘接剂对牙釉质和牙本质剪切粘接强度,以期为临床提供参考.方法 选择因牙周病拔除的上颌中切牙20颗,使用两种自酸蚀粘接剂[A(ClearfilTM Protect Bond)、B(AdporTM PromptTM)]和两种全酸蚀粘接剂[C(SwissTEC SL Bond)、D(Single Bond)]按照厂家推荐步骤对牙釉质和牙本质进行粘接,并测试牙釉质和牙本质粘接样本的剪切粘接强度.结果 4种粘接剂对牙釉质和牙本质粘接强度分别为:粘接剂A(25.33±2.84)、(26.07±5.56)MPa;粘接剂B(17.08±5.13)、(17.93±4.70)MPa;粘接剂C(33.14±6.05)、(41.92±6.25)MPa;粘接剂D(22.51±6.25)、(21.45±7.34)MPa.粘接剂C对牙釉质和牙本质剪切粘接强度显著高于其他3种粘接剂(P<0.05);粘接剂B的剪切粘接强度显著低于其他3种粘接剂(P<0.05).结论 本研究所选用的自酸蚀两步法粘接剂的剪切粘接强度与部分伞酸蚀粘接剂相当,高于自酸蚀一步法粘接剂.     

Effect of previous treatments on bond strength of two self-etching adhesive systems to dental substrate

PURPOSE: The aim of this study was to evaluate the effectiveness of previous dental substrate treatments on the bond strength of two self-etching adhesives. MATERIALS AND METHODS: One hundred bovine incisors were sectioned at the cementoenamel junction. The labial tooth surface was ground to obtain flat superficial dentin. Teeth were randomly divided into two groups (n = 50): Clearfil Protect Bond and One Up Bond F. The specimens of each group were subdivided into five groups, according the dental substrate treatment, and then the adhesive system was applied as follows (n = 10): C: control, without previous treatment; TA: 37% phosphoric acid etching on enamel and dentin for 15 s; PA: 37% phosphoric acid etching only on enamel for 15 s; SB: Al2O3 sandblasting on dental surface; EDTA: enamel and dentin conditioning with 24% EDTA gel, pH 7.0. Resin composite blocks were fixed to the dental surfaces with dual-polymerized resin cement. Samples were sectioned in the mesiodistal direction and were trimmed to reduce the cross-sectional area to approximately 1.2 mm2. They were tested at a crosshead speed of 0.5 mm/min on a testing machine. Microtensile bond strength values from enamel, superficial dentin, and deep dentin were compared. Mean microtensile bond strength values were expressed in MPa and were analyzed by two-way ANOVA (2 x 3 x 5) and Tukey's tests. RESULTS: A significant difference was observed for interaction (p = 0.00001) among the factors. The highest mean bond strength to enamel was found with previous phosphoric acid etching, and to dentin when EDTA was previously applied. CONCLUSION: The most indicated previous treatment for increasing the bond strength to enamel and dentin simultaneously is EDTA for both self-etching adhesive systems used.     

The microtensile bond strength of self-etching adhesives to ground enamel

It is uncertain whether single-phase self-etching adhesives form bonds to enamel as reliable as those of etch-and-rinse adhesives. This study compared the microtensile bond strengths to ground enamel of three self-etching adhesive systems, a self-etching primer system and an etchand-rinse adhesive system. Human enamel was ground flat with 320-grit silicone carbide paper. The self-etching adhesives iBond (Heraeus Kulzer), Prompt L-Pop (3M ESPE) and Xeno III (Caulk/Dentsply), the adhesive with a self-etching primer Clearfil SE Bond (Kuraray) and the etch-and-rinse adhesive Scotchbond Multipur-pose (3M/ESPE) were applied as directed, followed by a core of the same manufacturers' hybrid resin composite. A microtensile bond strength evaluation was performed after 48 hours of water storage, using untrimmed beams approximately 0.9 mm2 in cross-sectional area at a crosshead speed of 0.6 mm/minute. There were no pretest failures in any group, and failures were predominately adhesive or mixed. Adhesion to enamel of Clearfil SE was not significantly different from Scotchbond Multi-Purpose, while the three self-etching adhesive systems demonstrated significantly lower bond strengths (One-way ANOVA, Tukey-Kramer Multiple-Comparison Test, p < 0.00001).     

复合树脂联合两种酸蚀粘结剂与乳牙釉质及牙本质的剪切粘结强度比较

目的:比较复合树脂联合全酸蚀和自酸蚀粘结剂与乳牙釉质及牙本质的剪切粘结强度。方法:收集新鲜拔除的滞留乳磨牙48个,随机分为4组,分别制备全酸蚀和自酸蚀粘结剂的釉质和牙本质试件,电子万能试验机测定各组剪切强度;体视显微镜下观察试件断面的破坏模式;扫描电镜观察粘结界面情况。结果:全酸蚀粘结剂组的釉质剪切强度明显高于牙本质剪切强度(P<0.05);自酸蚀粘结剂组釉质与牙本质剪切粘结强度无统计学差异(P>0.05);全酸蚀粘结剂组的釉质、牙本质剪切粘结强度均明显高于自酸蚀粘结剂组(P<0.05);体视显微镜及扫描电镜观察均显示,全酸蚀粘结剂与釉质和牙本质的粘结界面结合程度好于自酸蚀粘结剂。结论:全酸蚀粘结剂处理对乳牙釉质及牙本质的剪切粘结强度高于自酸蚀粘结剂。     

Evaluation of nonrinse conditioning solution and a compomer as an alternative method of bonding orthodontic bracket.

Damage to the enamel surface during bonding and debonding of orthodontic brackets is a clinical concern. Alternative bonding methods that minimize enamel surface damage while maintaining a clinically useful bond strength are an aim of current research. The purpose of this study was to compare the effects of using two enamel conditioners and adhesives on the shear bond strength and bracket failure location. Forty freshly extracted human molars were pumiced and randomly divided into two groups of 20 teeth. Metal orthodontic brackets were bonded to the enamel surface by one of two protocols: 37% phosphoric acid with a composite adhesive (Transbond XT) or a nonrinse conditioner with a compomer adhesive (Dyract flow). The teeth were mounted in phenolic rings and stored in deionized water at 37 degrees C for 24 hours. A Zwick Universal Testing Machine was used to determine shear bond strengths in MegaPascals. The residual adhesive on the enamel surface was evaluated using the Adhesive Remnant Index. Student t-test and chi2-test were used to compare the two groups. Significance was predetermined at P < or = .05. The results of the t-tests indicated that there were significant differences between the two adhesive systems (t = 11.18 and P = .001) with the nonrinse conditioner/compomer system having lower shear bond strength (X = 1.7 +/- 0.9 MPa) than the phosphoric acid/composite adhesive (X = 10.4 +/- 2.8 MPa). The results of the Chi Square test evaluating the residual adhesives on the enamel surfaces also revealed significant differences between the two groups (chi2 = 7.62, P = .022). In conclusion, a nonrinse conditioner used with a compomer adhesive had significantly lower shear bond strength than a phosphoric acid/composite adhesive system.     

Bond strength of different adhesive systems to dental hard tissues

This study compared the shear bond strengths of different adhesive systems to enamel and dentin of different depths. The adhesive systems used were: Single Bond one-bottle total-etch; AQ Bond one-step self-etching, Clearfil SE Bond two-step self-etching and Tyrian SPE/One-step Plus two-step self-etching. Eighty extracted non-carious human mandibular molars were mounted in self-curing resin and the occlusal surfaces were ground with a mechanical grinder to obtain flat occlusal enamel surfaces. After applying the adhesive systems, a plastic tube was attached to the enamel surfaces. The tube was filled with a universal hybrid resin composite, which was then polymerized. The specimens were stored in water at 37 degrees C for 24 hours. Shear bond testing was carried out using an Instron Universal testing machine with a crosshead speed of 1 mm/minute. The occlusal enamel of the 80 teeth was removed to determine the bond strengths of the adhesives to superficial dentin. To obtain deep dentin, the same teeth were ground deep towards the pulp, with the remaining dentin thickness approximately 0.7 mm. The adhesives and restorative material were then applied to the prepared dentin surfaces following the methodology described above. For occlusal enamel surfaces, the bond strength of Single Bond was significantly higher than the other adhesives. Single Bond, Clearfil SE Bond and Tyrian SPE/One-step Plus performed equally when bonded to superficial dentin; the lowest bond strength was obtained with AQ Bond. On deep dentin, the highest bond strengths were obtained with Clearfil SE Bond. For each adhesive system, shear bond strength to enamel was statistically higher than it was to either superficial or deep dentin. There were no significant differences between shear bond strengths to superficial versus deep dentin, regardless of adhesive.