Abstract: Objectives: The aim of this in vitro study was to assess micro-shearbond strength (µSBS) of tertiary- butanol-based adhesive under moist and dry conditions and correlate the results to resin-tags surface-area. Methods:
Thirty-extracted human molars were used. Flat dentin surfaces were prepared on buccal and occlusal surfaces ready for bonding. Specimens were randomly divided into three-groups; G1: Prime&BondNT, applied to moist dentin (control), G2: XPBond, applied to moist dentin, and G3: XPBond, applied to dry dentin. Etch&Rinse technique was used for both adhesives as per manufacturer's instructions. For G3, dentin was air-dried for 10s before XPBond application. Three-microcylinders of composite-resin (TPH A2 shade, Dentsply) were bonded to buccal dentin of each specimen for µSBS testing, while 2mm composite-resin was bonded to occlusal dentin for tags surface-area analysis. Curing was performed for 40s (LED, Bluephase, Ivoclar/Vivadent). All specimens were stored in distilled water at 37°C for 24h. µSBS testing was performed using testing machine (Model LRX-plus; Lloyd-Instruments Ltd., Fareham, UK) and data were recorded using software (Nexygen-MT Lloyd Instruments). Each specimen was then sectioned mesio-distally to expose resin–dentin interface, examined at 1500X using Environmental-Scanning- microscope, and tags surface-area were calculated. Data were analyzed by Pair-wise Newman-Keuls multiple comparison and regression-analysis (P<0.05). Results: G2 (29.06MPa) showed insignificantly higher µSBS than G1 (25.45MPa), while G3 (17.3MPa) showed significantly the lowest µSBS. G3 produced significantly highest tags surface-area (200.4µm²) compared to G1 (149.4 µm²) and G2 (94.54 µm²). Conclusion: - Butanol-based adhesive bonded to moist dentin, produced high µSBS and hybrid layer with short resin-tags that showed a perfectly infiltrated and sealed dentin-resin interface, - bonding to dry dentin showed lower µSBS, - there was significant correlation between tags surface-area and µSBS for G1&G2, - no correlation was found for G3. Acknowledgement:
All the data obtained for the shearbond strength of different indirect prosthodontic composites was sub- jected to Weibull analysis. The use of Weibull distribu- tions has proved to be a good method for the evaluation of the fracture behavior of materials . This distribu- tion is used where bond strength measurements and predictions are important. In addition, this distribution predicts the probability of bond failure under a specific stress value. However, it have to be highlighted that the sample size of this study limits the reliability of the Weibull analysis and therefore results can only be con- sidered as indicative only. BG resin composite compared with the other prosthodontic resin composites provided a more durable bond to alumina. This composite was also observed to have a high likelihood of resisting frac- ture at low and high stress levels. The SF veneering ma- terial applied to alumina resulted in a weaker bond compared with the other veneering composites. The SF composite was polymerized at the lowest polymerization temperature of the tested prosthodontic composites, which may explain the lower bond strength values.
in bond strength was only significant in the group in which the repair composite resin was methacrylate-based similar to the hydrophobic resin compared to the group in which the hydrophobic resin was not used. In the group in which an extra layer of hydrophobic resin was used but the repair composite resin was silorane-based, the mean bond strength was higher compared to the group without the hydrophobic resin; however, this increase was not statistically significant. It has been shown that with an increase in the hydrophobicity of the intermediate resin, its water sorption and consequently its hydrolytic degradation decrease . This finding is of high clinical significance because dentists often do not know whether the composite to be repaired is a silorane- or a methacrylate-based composite and may routinely use a methacrylate-based composite for this purpose. In the current study, higher repair bond strength in group 3 might be attributed to the use of silorane bonding agent and Scotchbond multi-purpose, both of which
In the present study, the shearbond strength between denture base resin and acrylic teeth with surface modifications of the ridge lap area was evaluated and compared with that of unmodified teeth.
Surface modifications such as, placement of vertical and horizontal retentive grooves, treating the ridge lap area with a combination of methyl methacrylate monomer and dichloromethane, sandblasting of the ridge lap area with 250µ aluminium oxide have been employed in this study to know their effect on the bond strength between acrylic resin teeth and denture base resin. The sample size in each test group was limited to ten samples based on that followed in similar studies [2,5,7,18]
from the same manufacturer as follows: Bistite II/Tokuso Ceramic Primer, Linkmax/GC Ceramic Primer, RelyX ARC/RelyX Ceramic Primer, Panavia F 2.0/Clearfil Ceramic Primer, and Resicem/Shofu Porcelain Primer and Resicem/AZ Primer. Stainless steel rods were bonded to the ceramic surfaces using one of the five resin cements. After 24-h water storage, the tensile bond strengths were tested using a universal testing machine. Result shows Conditioning with primers containing a silane coupling agent (all the primers except AZ Primer) significantly enhanced bond strengths of resin cements to silica-based ceramic. For zirconia ceramic, Resicem/AZ Primer exhibited significantly higher bond strength than the other groups except Panavia F 2.0/Clearfil Ceramic Primer. Thus the use of primers containing a silane coupling agent improved resin bonding to silica-based ceramic. On the other hand, the use of primers containing a phosphoric acid monomer or a phosphate ester monomer improved resin bonding to zirconia ceramic.
Usually after the tooth bleaching procedures, pa- tients ask for other esthetic treatments, namely re-
placement of old composite restorations and ex- change of amalgam fillings with tooth-colored res- torations. After the bleaching procedure, residual oxygen and remnants of hydrogen peroxide are still present in tooth structures and prevent the po- lymerization of the adhesive resin and formation of resin tags in the etched enamel. Clearly, this issue influences the bond strength and compromises the long-term service of restorations [3,4].
sandblasted surfaces of BegoStar and gold coin alloys did not significantly change the bond strength and the lowest bond strength was reported in alloy specimens treated with sandblasting + alloy primer; while sandblasting alone yielded the highest bond strength in the mentioned two groups. This finding is in contrast to the claims of the alloy primer manufacturer since according to the manufacturer’s instruct- tions the alloy surface has to be sandblasted before the application of alloy primer. Different testing techniques or phases of the test may be responsible for this difference. Based on the study results, Nano Met Etch is recommended for use in alloys with a higher content of gold and lower content of Pd and Ag. In conclusion, since the minimum bond strength for optimal durability of bonded restorations is suggested to be 20 MPa, this study revealed that surface treatment of the three understudy alloys with Nano Met Etch was clinically efficacious. In order to generalize the results, these surface treatments have to be tested on high noble alloys with different compositions. The effects of storage in water and pH changes simulating the oral environment should also be evaluated. The impact of dynamic loading and the resultant fatigue on the durability of resinbond and also the effect of thermocycling on the bond strength have to be studied as well.
The aim of this study was to evaluate the micro-shearbond strength and mode of failure of two resin based cements, dual or self-adhesive, photoactivated through different ceramic thicknesses. Sixty discs with a diameter of 12mm were constructed with IPS Empress Esthetic ceramic, and divided into three groups according to their thickness (0.7; 1.4 and 2.0mm). The surface was treated with 10% hydrofluoric acid for 60 seconds, air-jet rinsed and dried for 60 seconds, and cleaned in an ultrasonic bath with distilled water for 10 minutes. The insertion of the Variolink II and RelyX U200 resin cements on the ceramic was carried out using elastomer matrix with four holes of 1.5mm in diameter, positioned on the etched surface of the disc. A device equipped with a LED lamp was used to make the photoactivation was carried out through the ceramic disc for 60 seconds. The samples were water stored at 37°C for 24h in a closed container kept away from light. After storage, a micro-shearbond strength test was performed with a crosshead-speed of 1 mm/min with load of 50Kg until fracture and bond strength values were calculated in MPa. To analyze the mode of fracture, the samples were evaluated with a stereomicroscope at 10 times magnification. The results were analyzed using two-way ANOVA and the means compared with Tukey’s post-hoc test (p< 0.05). The results showed that for each resin based cement, the thickness factor was not statistically significant (p=0.541 and p=0.643, respectively). Variolink II cement showed significantly higher bond strength than RelyX U200 (p = 0.009) for all ceramic thickness levels.
Abstract: OBJECTIVES: The aim of this study is to evaluate the adhesion between PEEK and two self- adhesive resin cements after plasma treatment. METHODS: Eight hundred sixty-four polyetheretherke- tone (PEEK) disks were cut and polished to silicon carbide (SIC) P4000. One half of the specimens were randomly selected and pretreated with plasma, whereas the remaining 432 specimens remained untreated. Subsequently, specimens were randomly allocated to four groups (n = 108/group): Visio.link (Bredent), Signum PEEK Bond (Heraeus Kulzer), Ambarino P60 (Creamed), and a control group without additional treatment. Half of the specimens of each group (n = 54) were then cemented with either RelyX Unicem Automix 2 (3 M ESPE) or with Clearfil SA (Kuraray). All specimens were stored in water for 24 h (37 °C). Afterwards, specimens were divided into three groups (n = 18) for different aging levels: (1) no aging (baseline measurement), (2) thermal aging for 5,000 cycles (5/55 °C), and (3) thermal aging for 10,000 cycles (5/55 °C). Thereafter, shearbond strengths (SBS) were measured, and failure types (adhesive, mixed, and cohesive) were assessed. Data were analyzed using descriptive statistics, four- and one-way ANOVA followed by a post hoc Scheffé test (p < 0.05). RESULTS: No adhesion could be established without adhesive pretreatment, irrespectively, whether plasma was applied or not. Also, no bond strength was measured when Ambarino P60 was applied. In contrast, adhesive pretreatment resulted in SBS rang- ing between 8 and 15 MPa. No significant differences were found between the resin cements used. In general, no cohesive failures were observed. Groups without plasma treatment combined with Visio.link or Signum PEEK Bond showed predominantly mixed failure types. Control groups, plasma treated, or treated using Ambarino P60 groups fractured predominantly adhesively. CONCLUSION: The use of methyl methacrylate (MMA)-based adhesives allows bonding between PEEK and self-adhesive resin cements. Plasma treatment has no impact on bond to resin cements. CLINICAL SIGNIFICANCE: PEEK reconstructions can be cemented using self-adhesive resin cements combined with pretreatment with MMA-based adhesives.
This adhesion mechanism is similar to the mechanism of adhesion of self-etch resin bonding agents with mild acidity. The only difference is that the molecular weight of the carboxyl-based monomer present in GI is much greater than the molecular weight of acidic monomers present in self-etch resin bonding agents. Thus, the GI monomers have less penetration and subsequently, shorter resin tags are formed resulting in a weaker bond and greater microleakage . On the other hand, the commonly used self-etch adhesives (both 6 th and 7 th generations) are divided into three groups in terms of acidity: mild, moderate and strong. Strong self-etch adhesives have a pH of N1 and as stated earlier, they can cause extensive demineralization as in total etch technique while
oxygen free radicals. The findings of our study showed equal antioxidant efficacy of grape seed and sodium ascorbate, which is in accord with the results of Vidhya et al,  and Sharafeddin et al, . Two in-vitro studies demonstrated that grape seed extract inhibited the demineralization and enhanced the remineralization of carious root lesions [4,33]. The results of microscopic analysis confirmed the findings of shearbond strength testing in our study, since group 2 with the lowest bond strength value had the highest frequency of adhesive failure. In the current study, antioxidants were applied in the form of solution. Use of antioxidants in the form of hydrogel is recommended in future studies. In the current study, antioxidants were used for 10 minutes. Other studies are required to assess the effect of higher concentrations of antioxidants with shorter application times. Since antioxidants have a short shelf life, future studies are recommended to focus on the storage methods of antioxidants. The current study had an in-vitro design and clinical studies are needed to further elucidate this issue.
Mode of failure during bond strength determination was also not determined, which was another drawback of the study.
Therefore, based on the results of the study, it can be said that nanocomposites are ideal for both anterior and posterior restorations as they possess excellent esthetic and mechanical properties. This is analogous to the investigations done by previous researchers who demonstrated that microfilled composite resin exhibited the lowest mechanical properties and nanofilled resin composites showed mechanical properties as good as those of universal hybrids and therefore can be used in similar clinical situations .
performance with very low post operative sensitivity. Ethanol/
water based adhesive maintains its shearbond strength overtime to yield an outstanding shelf life 74 .
The composite resin used in this study is Filtek Z-250 universal restorative (3M ESPE). It is indicated in direct anterior and posterior restorations in primary and permanent molars, sandwich technique with glass ionomer restorative material , cusp build up etc. it offers less polymerization shrinkage, remarkable wear resistance , excellent fracture toughness and overall strength. Also an increment of 2.5mm of Filtek Z250 needs to be light cured only for 20 seconds 74 .
Yip. HK, Smales RJ. et al (2000) 133 Conducted a study to compare the fluoride ion release from a freshly mixed polyacid modified resin composite, or compomer (Dyract) and three resin modified glass ionomer cements (Fuji II LC, Photac-Fil, and Vitremer) and to compare the use of 3 units for measuring fluoride release.Fluoride measurements were carried out using a fluoride ion-selective electrode connected to a pH ion-selective electrode meter. Fluoride ion release was measured in parts per million, micrograms per square centimeter, and micrograms per cubic millimeter. Showed Fuji II LC, Photac-Fil, and Vitremer showed high initial release values which decreased exponentially and then showed a slow decline during the ensuing time. Dyract released significantly less fluoride ions during the first 84 days than did the three resin – modified glass ionomer cements and maintained this low level of release throughout the study period. The amounts of fluoride ion release measured at any time interval varied with the units of measurements chosen but the pattern of release remained the same. They concluded that there was a wide variation in the amounts of fluoride ions released from related products, but the patterns of release were similar and unaffected by the units of measurements used.
However, according to a study by Inokoshi et al., 
pre-treatment of zirconia with Clearfil Ceramic Primer or Monobond Plus yielded the best results; they ex- plained that these primers contained silane monomer and low bonding values were registered for Z-Prime Plus, in contrast to the results of the present study. The bond strength values that they recorded for Z-Prime Plus were somewhat unexpected and were inconsistent with the more acceptable bond strength by other re- searchers, which they had also mentioned. They pre- pared micro-specimens for tensile test and assigned random values of 0 and 10 MPa for pretesting failure of samples. This might have affected the bond strength values in their study.  Kim et al.  reported that the silane could not contribute to chemical bonding to zirconia ceramic because there is no silica in the zirco- nia structure. In addition, they found that the All-Bond Universal and Single-Bond Universal adhesive exhibit significantly higher bond strength than the primers con- taining conventional MDP.  That is in contrast to the results of the present study; however, they used the Alloy Primer as a conventional MDP-containing primer, in contract to Alloy Primer that contains 6-(4-vinyl ben- zyl-n-propyl amino)-1, 3, 5-trazoine-2, 4-dithione ( VBATDT ) and acetone solvent. This monomer contains sulfur and, it was selected to promote the adhesion to noble and base metal alloys greatly. [15, 32] In the cur- rent study, the Z-Prim Plus containing ethanol and two adhesive monomers (carboxylate and MDP) were used as a conventional MPD-containing primer. It was in contrast with the present study.
We also showed that the differences in frequen- cies of the failure mode were not significant within control and test groups except for the groups that were irradiated with 2W (100 mJ/20 Hz) and 5W (250 mJ/20 Hz) power output. Based on an analysis of the failure sites, the major failure pattern was the adhesive failure. According to these findings, no cohesive fail- ure was observed in the porcelain and only a few sam- ples had a cohesive failure in the resin composite. It may be inferred that in spite of improvement of the bond strength between the resin composite and the feldspathic porcelain surface through various surface treatments, this bond was still not strong enough and was lower than the cohesive resistance of resin compo- site and the porcelain.
HF-etching is known to leave residual salts of silica fluoride that precipitate [18–
20] and can be identified as a white deposit on the etched ceramic surface. Leaving this debris could negatively influence the resinbond strength [21, 22]. Several clean- ing methods have been suggested to remove those debris, including ultrasonic clean- ing in distilled water, 95% alcohol or acetone [19, 21, 22]. Some authors have described the association between brushing the surface with phosphoric acid and immersion in an ultrasonic bath to remove the crystalline debris from the etched surface . It is agreed that the resistance of the resin-ceramic adhesion zone is controlled primarily by the microstructure and surface treatment of the ceramic [6, 22, 23]. Each new material or product must therefore be studied individually to define the optimal bonding proto- col. Lithium-disilicate ceramics are among those new materials that have been marketed with great success and deserve special attention for increasing the limited knowledge database regarding optimal resin bonding techniques.
Kulkarni et al 33 (2007) studied the effect of denture base surface pre- treatments on the bond strength of two long term resilient liners. They found out that chemical agents such as monomer application increased the bond strength whereas sandblasting resulted in a decrease of bond strength. The effect of roughening the surface of the denture base on the bond strength of the soft liner is not well established. Craig et al 13 advocated a roughened surface to improve the adhesive bond strength whereas Amin et al 6 reported that roughening the acrylic resin base by sandblasting before applying liner material had a weakening effect on the bond. Minami 41 also found that liners bonded to smooth surface had better bond when compared to those bonded to air abraded surface. He proposed that air abraded resin surfaces may have pits, cracks, crevices, discontinuities with sharp corners and projections. These surface irregularities may not allow complete flow of the soft denture liner and may result in the formation of small voids by air entrapment. Therefore, stress concentrations may be developed in the vicinity of the bonding interface and initiate failure during bond strength testing.
The SBS of group 2 was not different from the control group.
Group 2: Silane Primer is a resin-containing silane coupling agent which was developed to reduce clinical surface pretreat- ment steps and expected to bond with resin in the resin luting cement. Chen et al study on Silane Primer application on etched lithium disilicate surface contact angle was not signiﬁ- cantly different from untreated etched lithium disilicate sur- face angle. The similar contact angle of unetched and etched lithium disilicate glass-ceramic suggested that the chemical bond between LDGC surface and silane did not occur or only slightly occurred. There are many factors affecting bond quality. Surface wettability and surface energy are some of the factors. The additive-like resin may impede condensation reaction of the silane coupling agent, causing low-bond strength, low-contact angle, 19 and does not enhance bond strength between RC and LDGC. 20 The condensation reaction formed stabilized siloxane and released water. The addition of resin in the silane coupling agent may delay water vaporiza- tion. 19 Adding resin in silane coupling agent causes instability of the chemical substrate and might interfere with the con- densation reaction of the hydroxyl group on the lithium disilicate surface and silanol. 19 The pH value of Silane Primer is at 7.3 which has lower acidity than an appropriate hydrolysis pH which occurs at 4. 21 Furthermore, Dimitriadi et al 22 stated that Silane Primer showed slight silanol activity, Table 3 Means and SD of SBS obtained from each respective silane surface treatment groups in MPa and mode of failure
In the first experimental group, Assure Universal Bonding Resin (Reliance orthodontic products, Itasca, IL) was used. All etching, rinsing and dry- ing procedures were done according to Transbond XT protocol. Assure sealant was appliedin two- coats tothe buccal crown surface, left for 10 seconds, and dried slowly. Assure adhesive and Transbond XT composite wereapplied to the bracket base, and the bracket was positioned exact- ly on the tooth and compressed to expel the excess adhesive. The specimens were cured for onesecond to obtain adequate appearance. Then, excess adhe- sives were removed from around the brackets’ base followed by another round of light curing for 10 seconds.