Shear Bond Strength Of Resin Research Articles

The effect of bacterial cellulose nanocrystals on the shear bond strength of resin modified glass ionomer cement to dentin.

BackgroundThe present study aimed to investigate the effect of bacterial cellulose nanocrystals (BCNC) on the shear bond strength (SBS) of resin modified glass ionomer cement (RMGIC) to dentin. Material and MethodsA total of 48 freshly extracted intact third molars were randomly divided into four main groups with three different concentrations (0.3%, 0.5% and 1% wt) of BCNC with RMGIC and control group without BCNC. These specimens were kept in distilled water at 37° C for 24h. Shear bond strength was examined, using the universal testing machine. Kruskal-Wallis test and Dunn`s post-hoc test were applied for analysis of data. P<0.05 was considered as the level of significance. ResultsThe addition of a 1%wt of BCNC to the RMGIC led to a significant increase in the shear bond strength (7.17 ± 2.14) compared to the control group (2.09 ± 1.80) (P=0.007). The shear bond strength was improved up to 343%. ConclusionsIt was found that the incorporation of 1% wt BCNC to the RMGICs enhanced the SBS properties of the RMGIC significantly. Modifying RMGIC with BCNC might be advantageous in terms of improving the restorative material. Key words:Bacterial cellulose nanocrystals, RMGIC, Shear bond strength.

Challenging the Resin-Zirconia Interface by Thermal Cycling or Mechanical Load Cycling or Their Combinations

The purpose of this in vitro study was to evaluate the influence of mechanical load cycling (MLC), which simulated mastication, alone or combined with thermal cycling (TC), on the resin shear bond strength (SBS) to zirconia. Two resin cements (Panavia F2.0 and RelyX U200) were bonded (bonding area: 2.38 mm) to air-abraded zirconia (Everest ZS-Ronde). The specimens were subjected to SBS test before and after TC (5000 cycles), MLC (5000 cycles in 37 °C water), TC/MLC, or MLC/TC aging (n = 15). Before SBS test, the mechanical and physical properties of the two resin cements were studied (n = 5). For both resins, unlike TC (p &gt; 0.05), the three MLC-containing aging conditions significantly decreased the SBS values when compared to the non-aged condition (p &lt; 0.05). In the case of MLC-only aging, RelyX U200, with significantly higher hydrophobicity (p = 0.004), showed a significantly higher SBS value than Panavia F2.0 (p = 0.035). The MLC aging-containing groups showed increased occurrence of mixed failure. The application of MLC combined with TC may more closely simulate intraoral conditions.

The effect of bleaching on shear bond strength of resin bonded bridges

Sixty intact upper central and lateral incisors were used in this study the teeth were divided into four groups, the first group was the control group the other groups were bleached with (10%)carbamide peroxide (Opalescence 10%) for two weeks the bleaching material was changed every (8) hours. Sixty discs shaped samples were cast from nickle chromium CB Blando 72 alloy the diameter of each sample was (5) mm and the thickness was (1) mm, the bonding surfaces were sandblasted. The discs were bonded to the teeth in the first and second groups one day after bleaching, the third group was bonded one week after bleaching while the fourth group was bonded two weeks after bleaching. The bonding material used for all groups was Super Bond Crown and Bridge Material. The shear bond strength of the samples was tested. The statistical analysis showed that the second group has the lowest bond strength while the fourth group showed the highest bond strength. This indicates that bleaching affects the bond strength of resin bonded bridges fabricated from CB Blando 72 nickel chromium alloy so that bridges must be fabricated at least two weeks after bleaching

Comparison between Shear Bond Strength of Er:YAG and Er,Cr:YSGG Lasers-Assisted Dentinal Adhesion of Self-Adhering Resin Composite: An Ex Vivo Study.

(1) Background: Bonding composite to tooth structure is still evolving with a substitute for phosphoric acid being the main challenge. Lately, a self-adhering composite (SAC) was developed, promising to simplify bonding to tooth structure. Unfortunately, retention especially to dentin, was not as good as the gold standard three steps bonding system. During the last 2 decades, lasers were used to enhance shear bond strength of composite to tooth structure. However, the literature provided limited information regarding laser efficiency in the immediate, as well as the long term, adhesion success of SACs to dentin. The purpose of our study was to define the optimal irradiation conditions to improve the adhesion of self-adhering flowable resin composite to dentin exposed to Er:YAG and Er,Cr:YSGG laser irradiation. (2) Methods: Seventy-two freshly extracted human third molars, prepared to have flat dentinal surfaces, were randomly divided into three groups (n = 24) including a control group (Group 1) in which dentin was left without laser irradiation. The other two groups (Group 2 and 3) received standardized irradiation at a speed of 1 mm/second with Er:YAG (60 mJ; SSP mode = 50 μs; 10 Hz; fluency of 9.4 J/cm2; beam diameter: 0.9 mm; air 6 mL/min; and water 4 mL/min), and Er,Cr:YSGG: 1.5 W; fluency of 17.8 J/cm2; turbo handpiece with MX5 short insert; 20 Hz under air/water spray (65% air, 55% water). Self-adhering flowable resin was applied to dentin in all groups. Half of the specimens were stored in water for 24 h while the other half underwent 3000 thermal cycles. Later, all specimens received a shear bond strength test. Fracture observation was done first under a stereomicroscope then by using a scanning electron microscope. (3) Results: The mean values of shear bond strength for both laser-treated dentin groups (Er:YAG laser: 13.10 ± 1.291, and Er,Cr:YSGG: 14.04 ± 5.233) were higher than in the control group 1 (8.355 ± 2.297) before thermocycling. After thermocycling, shear bond strength decreased in all groups as follows: 10.03 ± 1.503, 10.53 ± 2.631, and 02.75 ± 1.583 for Er:YAG, Er,Cr:YSGG, and nonirradiated dentin, respectively. Shear bond strength values showed a significant difference between the control group (Group 1) and both lasers groups (Group 2 and 3). Statistical analysis of stereomicroscope observation revealed no significant difference between laser irradiation and failure mode (p < 0.136). SEM observation of the dentin surface in both laser-irradiated groups showed opened tubules, absence of smear layer as well as an increase of resin infiltration into dentinal tubules. (4) Conclusion: Er:YAG and Er,Cr:YSGG lasers enhance self-adhering flowable resin shear bond strength values and improve its longevity by eliminating the smear layer, opening dentinal tubules and increasing resin infiltration into the microstructure.

Assessing the Effects of Air Abrasion with Aluminum Oxide or Glass Beads to Zirconia on the Bond Strength of Cement

The purpose of this study was to evaluate the effects of air abrasion with aluminum oxide or glass beads to three types of zirconia containing various levels of cubic crystalline phases (3Y-TZP, Katana ML; 4Y-PSZ, Katana STML; and 5Y-PSZ, Katana UTML, Noritake) on the shear bond strength of resin cement. Thirty block specimens (8 × 8 × 3.5 mm) were milled out of each zirconia material and mounted in plastic pipe. Ten specimens of each of the zirconia materials were air-abraded using 50 μm aluminum oxide particles, ten specimens were abraded using 80 μm glass beads, and ten specimens served as a control and received no surface treatment. A zirconia primer was applied to the surface of the zirconia specimens. Composite disks were bonded using a resin cement and light-cured. The specimens were stored in 37°C distilled water for 24 hours and thermocycled for 2,500 cycles. The specimens were loaded in shear on a universal testing machine. Data were analyzed with one-way and two-way ANOVAs and Tukey's post hoc tests (α = 0.05). A significant difference in shear bond strength was found based on the surface treatment (p < 0.001), but not on the type of zirconia (p = 0.132). Air abrasion with glass beads or no surface treatment resulted in significantly lower bond strength of the resin cement to all three zirconia types compared to air abrasion with aluminum oxide. Although air abrasion with aluminum oxide may reportedly be more likely to weaken cubic-containing zirconia compared to air abrasion with glass beads, the use of aluminum oxide results in greater bond strength of the resin cement.

An in-vitro analysis of shear bond strength of resin based luting cements to lithium disilicate glass ceramic

Lithium-disilicate glass-ceramic (LDGC) material was introduced in the year 2000; it improved the strength of single and multiple-unit restorations. The inherent brittleness and limited flexural strength of the available glass-ceramic material were the major drawbacks of these restorations. Adequate adhesion between ceramic and tooth substructure was vital for the successful functioning of ceramic restoration. Limited information is available about the currently available luting systems. Aims and objectives: The present in-vitro study was designed to compare and evaluate the shear bond strength of three different resin based luting cements to lithium disilicate glass ceramic. The study was conducted to evaluate the shear bond strength of different resin based luting cements to lithium disilicate glass ceramic. Methods and Methodology: Thirty lithium disilicate glass ceramic disks were fabricated and were surface treated. The ceramic specimen were divided into three groups that received three different luting cements (Group 1: RelyX Ultimate Clicker, Group 2: Fusion Self Lute and Group 3: ParaCore). The shear bond strength of adhesive resin cement to the ceramic substrate was then measured with a Universal testing machine (Multitest 10-I, Mecmesin). Following de-bonding, all fractured interfaces were visually analysed from the Scanning electron microscope photomicrographs to determine the mode of fracture. Results: The study results demonstrated that there was no statistical significant difference between RelyX and Fusion Self Lute while there was statistically significant difference between RelyX and ParaCore (p=0.019, p Conclusion: the study concluded that the resin cements containing filler particles show higher bond strength values when compared to resin cements with no filler particles and bonds which fail by cohesion exhibit high-strength performance. Keywords: luting, Ceramic, High- strength.

Evaluation of Zirconia Surfaces after Strong-Acid Etching and Its Effects on the Shear Bond Strength of Dental Resin Cement.

The present study was intended to investigate changes in the microstructure and phase transformation of zirconia surfaces using etching and airborne-particle abrasion (AB) and the effects of these processes on the shear bond strength of dental resin cements to zirconia. Four groups were classified according to the surface treatment as follows: etching for 15 min (ET15), etching for 30 min (ET30), AB, and etching for 15 min following AB (ABET). These groups were then classified into two subgroups (a total of 8 groups with 11 specimens/group) according to the resin cement used for bonding, namely, Rely-X U200 (3M ESPE, St. Paul, MN, USA) or Panavia F 2.0 (Kuraray, Kurashiki, Okayama, Japan). Shear bond strength testing was performed using a universal testing device. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were also performed. When using Rely-X U200, ET15 exhibited the highest mean shear bond strength; the strengths of ET15, ABET, and ET30 were significantly higher than that of AB. When using Panavia F 2.0, ABET demonstrated the highest mean shear bond strength; the strengths of ABET and ET15 were significantly higher than those of ET30 and AB. The etched surface of zirconia could be observed using SEM, and the phase transformations resulting from each surface treatment were detected by XRD. Strong-acid etching of zirconia induced significant surface changes that increased the shear bond strength of resin cement, and the resin adhesive strength was higher when zirconia was etched with strong acid vs. AB alone.

The difference between porcelain and composite resin shear bond strength in the administration of 4% and 19.81% silane

Background: Damage to porcelain restorations such as fractures requires a repair that can be performed either directly or indirectly. Direct repair involves directly performing restoration of fractured porcelain with a composite resin application. This technique has more advantages than indirect repair because it requires no laboratory work and can be completed during a single visit. Silane, on the other hand, has been widely used and is reported to increase porcelain and composite resin attachments during the direct repair process. Purpose: This study aimed to determine the differences in shear bond strength between porcelain and composite resin during the administering of 4% and 19.81% silane. Methods: 27 porcelain samples were divided into three groups, namely: Group A - 4% silane, Group B - 19.81% silane and Group C - no silane, prior to the application of composite resin. Each sample was tested for shear bond strength by means of Autograph and fracture analysis performed through stereomicroscope and scanning electron microscope tests. Data analysis was subsequently performed using an ANOVA test. Results: There was a significant difference between the three groups with p=0.000 (p&lt;0.005). The lowest bond strength was found in the group without silane, while the highest was in the group with 4% silane (p&lt;0.005). Conclusion: The use of 4% silane can produce the highest shear bond strength of porcelain and resin composite.

In vitro evaluation of shear bond strength of resin cements to computer-aided design/computer-aided manufacturing (CAD/CAM) framework materials

The aim of this in vitro study was to compare the shear bond strength (SBS) of three different resin cements to different computer-aided design/computer-aided manufacturing (CAD/CAM) framework materials (cobalt-chromium, titanium, and zirconia). Specimens (12 x 2 mm) were divided into three different main groups according to materials (n=10); Cr-Co discs (Hard metal; HM), titanium discs (T), and zirconia discs (Z) and embedded in acrylic resin, and smoothed with silicon carbide papers and sandblasting with 50 μm aluminum oxide. Specimens of each framework materials were divided into three subgroups; (1) Universal resin cement, (2) Syringeable resin ionomer cement, and (3) Self-adeziv resin cement. The shear bond strength test was conducted using a universal testing machine. Data (MPa) was analyzed using one way ANOVA, Kruskal Wallis tests, and post-hoc tests. There was no statistically significant difference between SBS value of universal resin cement and self-adhesive cement for each material (P > 0.05). Resin ionomer cement showed the lowest SBS value (P < 0.05). No significant differences in SBS were found between framework materials. The SBS values of self-adhesive cements are as high as universal resin cements for hard metal, titanium and zirconium supported restorations. Keywords : Shear bond strength, hard metal milling, titanium, zirconia. DOI : 10.7176/JSTR/5-2-11

Effect of selective infiltration etching on the bond strength between zirconia and resin luting agents.

To evaluate the shear bond strength of resin cements to zirconia treated with the selective infiltration etching technique (SIE). Forty-seven zirconia specimens were prepared with a sequence of silicon carbide abrasives, cleaned in an ultrasonic bath. Three samples were separated for atomic force microscope (AFM) analyses (one nontreated for control, one sandblasted, and one selective infiltration etched) and the remaining were randomly distributed in four groups, according to the combination of surface treatment and resin cement: group 1a (sandblasting + Variolink II), group 1b (sandblasting + Panavia SA Plus), group 2a (SIE + Variolink II), group 2b (SIE + Panavia SA Plus). A composite resin cylinder (3 mm × 3 mm) was cemented to the zirconia surface, as per each group's specific protocol. After storing 24 hours in distilled water at 37°C, the specimens were tested for shear bond strength and the results were subjected to statistical analysis. At 24 hours, the highest SBS values were observed in group 2b, where the SIE technique was used in conjunction with Panavia SA Plus. Lowest values were found in group 1a. Increased surface roughness was observed with SIE. SIE significantly enhanced the resin bond strength to zirconia. However, cement selection was also an important factor, for both surface treatments tested. Use of SIE method combined with MDP monomer containing resin cement can provide clinically acceptable bond strength between zirconia and resin cement.

Evaluation of the effect of saliva contamination and cleaning methods on the surface free energy and shear bond strength of resin cements to zirconia ceramics

Objective: This study was designated to evaluate the effect of saliva contamination and cleaning methods on the surface free energy and the shear bond strength of resin cement to zirconia ceramics. Materials and Methods: A total of 80 samples were copy milled (CAD/CAM) from Zirconia blank. The samples were randomly divided into (4) groups (n=20) according to method of cleaning. Group 1 (control): No saliva contamination,Group 2: The samples cleaned with distilled water,Group 3: The samples cleaned with ivoclean, Group4:The samples cleaned with re-sandblasting. Each group was subdivided into 2 subgroups according to the type of adhesive resin cement (Multilink Speed and RelyX Ultimate) used (n=10). Each subgroup was further subdivided into two divisions according to the type of test (surface free energy and bond strength) performed (n=5). One-way analysis of variance ANOVA test and Tukey’ post hoc test were done for comparing variables. Results: The control groups record the lowest mean contact angle value (25.81°±1.76°) and the highest mean surface free energy value (107.57mN/m). While the group washed with water revealed the highest mean contact angle value (39.04°±0.68°) and the lowest mean surface free energy value (98.58 mN/m). Regarding shear bond strength the results showed that the highest shear bond strength value was recorded for the control group (14.33±1.98& 13.73±1.33 MPa), for Multi-link speed and Rely-X ultimate cement respectively , followed by re-sandblasting group, followed by ivoclean group, while the lowest shear bond strength value was recorded for the group washed with water (10.9±0.53& 8.22±0.85 MPa). However, regardless of the cleaning protocol groups, Multi-link speed cement recorded a higher mean shear bond strength value than RelyX Ultimate cement. However these difference was statistically non-significant except for the group washed with water (p=0.0003) as indicated by unpaired t test. Failure modes for all groups were evaluated, failure modes was either adhesive, cohesive or mixed, with frequency ranging from 20 to 40% for each type of failure. The group washed with water showed that allof cases of failure were of the adhesive type in both cement (100%). Conclusion: Cleaning of the contaminated ceramic surface before adhesive cementation is an indispensable step in order to achieve a strong bond. Moreover, the removal of surface contaminants by sandblasting and Ivoclean paste can be considered efficient cleaning methods for zirconia surfaces

Effect of phototherapy on shear bond strength of resin cements to zirconia ceramics: A systematic review and meta-analysis of in-vitro studies.

The present study systematically reviewed the literature to investigate the effect of phototherapy on the shear bond strength (SBS) of resin cement to zirconia ceramic. Electronic databases including MEDLINE (PubMed), ISI Web of Science, Scopus, ScIELO, LILACS and EMBASE until April 2018. The addressed focused question was: Does phototherapy increase the SBS of resin cement to zirconia ceramics?" A total of 8 in-vitro studies were included in the qualitative and quantitative analysis. The mean SBS for phototherapy ranged from 4.1 to 18.95 MPa while mean SBS for sandblasted zirconia-composite specimens ranged from 3.98 to 23.35 MPa in the included studies. Qualitative analysis showed 3 studies favoured application of phototherapy in significantly increasing SBS, while 4 studies indicated sandblasting showed significantly greater SBS of resin cement to zirconia ceramics. Considering the effects of phototherapy, significant heterogeneity for SBS (Q value = 136.37, p<0.0001, I2 = 94.87%) was noticed among both the groups. The overall mean difference for SBS (SMD = -0.59, 95% CI = -1.99 to -0.80, p = 0.402) was not significant between phototherapy and sandblast (control) groups. Whether the effect of phototherapy on increasing the SBS of resin cement to zirconia ceramic is debatable. Further in-vitro studies should be performed in order to obtain strong conclusions.

Influence of light activation of simplified adhesives on the shear bond strength of resin cements to a leucite-reinforced ceramic.

Objective:This study aims to evaluate the influence of the light activation of simplified adhesives on the shear bond strength of resin cements to a glass-ceramic. Three factors were evaluated: (1) cement in two levels (light cured and dual cured); (2) adhesive in two levels (Single Bond 2 and Single Bond Universal), and (3) light activation in two levels (yes or no).Materials and Methods:Thirty-two 1-mm thick slices of a leucite-reinforced glass-ceramic (IPS Empress CAD) were divided into eight groups according to adhesive (Single Bond 2 or Single Bond Universal), cement (AllCem Veneer or AllCem), and light activation of the adhesive before application of the cement (yes or no). Ceramic surfaces were etched for 60 s with 5% hydrofluoric acid, and adhesives were applied. Four cement cylinders were made over each ceramic slice (n = 16) and then submitted to shear bond strength tests.Statistical Analysis:Data were analyzed with three-way ANOVA and Tukey (α = 0.05).Results:There were significant differences between adhesives (P < 0.0001) and no differences between cements (P = 0.0763) and light activation (P = 0.4385). No interaction effect occurred (P = 0.05). Single Bond 2 showed higher bond strength than Single Bond Universal.Conclusions:The light activation of the adhesive before the application of the resin cement did not influence the bond strength.

Effect of non-thermal plasma on the shear bond strength of resin cements to Polyetherketoneketone (PEKK).

PURPOSEThis study aimed to assess the effect of non-thermal plasma on the shear bond strength of resin cements to polyetherketoneketone (PEKK) in comparison to other surface treatment methods.MATERIALS AND METHODSEighty PEKK discs were subjected to different surface treatments: (1) Untreated (UT); (2) Non-thermal plasma (NTP); (3) Sandblasting with 50 µm Al2O3 particles (SB); and (4) Sandblasting + Non-thermal plasma (SB+NTP). After each surface treatment, the contact angle was measured. Surface conditioning with Visio.Link was applied in all groups after pre-treatment. RelyX Unicem resin cement was bonded onto the PEKK specimens. After fabrication of the specimens, half of each group (n=10) was initially tested, while the other half was subjected to thermocycling (5℃ to 55℃ at 10,000 cycles). Shear bond strength (SBS) testing was performed using a universal testing machine, and failure modes were assessed using stereomicroscopy. The SBS results were analyzed statistically using one-way ANOVA followed by Tukey's post hoc test. Independent t-test was used to examine the effect of thermocycling (P<.05).RESULTSThe highest SBS values with or without thermocycling were observed with PEKK specimens that were treated with SB+NTP followed by the SB group. The lowest SBS results were observed in the UT groups.CONCLUSIONThe shear bond strength between PEKK and resin cements was improved using non-thermal plasma treatment in combination with sandblasting.

An ex vivo evaluation of effect of dentin pretreatment with various agents for varying time intervals on the shear bond strength of resin.

Background:This article highlights the contribution of collagen structure/stability to the bond strength. We hypothesize that induction of cross-linking in dentin collagen fibrils improves dentin collagen stability and thus bond strength with composite also improves.Aims:The aim of the study was to evaluate the effect of collagen cross-linking agents on the shear bond strength of composite resins.Subjects and Methods:One hundred human permanent teeth were randomly divided into three groups: Group I (n = 20) – no dentin pretreatment done, Group II – dentin pretreatment with 10% sodium ascorbate for 5 min (IIa) and 10 min (IIb), and Group III – dentin pretreatment with 6.5% proanthocyanidin (PA) for 5 min (IIIa) and 10 min (IIIb). A composite resin was bonded on prepared surfaces and cured. Thermocycling was done, and shear bond strength of the prepared samples was tested using a universal testing machine.Results:Values of Group I (control) were lowest whereas that of Group II (sodium ascorbate) were highest. The following order of shear bond strength was observed: IIb > IIa > IIIb ~ IIIa > I. Results for sodium ascorbate were found to be time dependent, whereas for PA, differences were nonsignificant.Conclusions:Treatment of dentinal surfaces with collagen cross-linking agent increases the shear bond strengths.

Composite resin shear bond strength on bleached dentin increased by 35% sodium ascorbate application

Background: Restoration of the teeth immediately after bleaching with 35% hydrogen peroxide (H2O2) is contraindicated due to the remnant of free radicals that will stay inside enamel and dentin for 1-3 weeks and reduce the adhesion of composite resin. Sodium ascorbate is an antioxidant substance known to bind free radical residues, thereby shortening the delay in restoration. Purpose: The purpose of this study was to examine the resin bond strength of bleached dentin influenced by the application of 35% sodium ascorbate. Methods: Nine premolars were divided into their crown and root sections, with the crown subsequently being cut into four equal parts to obtain 36 samples. These were then divided into four groups, each containing nine samples. Group A (control): samples were bleached using35% hydrogen peroxide, immersed in an artificial saliva, stored in an incubator at 37°C for seven days and then filled with a composite resin. Group B:samples were also bleached by means of 35% H2O2 followed by one application of 0.025 ml 35% sodium ascorbate for 5 minutes and restored with composite resin. Group C: samples were bleached with 35% H2O2, followed by two applications of 0.025 ml 35% sodium ascorbate for 5 minutes, and restored with a composite resin. Group D: dentin was bleached with 35% H2O2 followed by three applications of 0.025 ml sodium ascorbate 35% for 5 minutes and restored with a composite resin. The shear bond strength of the composite resin was measured by a universal testing instrument (Zwick, USA). Data was analyzed by means of one-way Anova and LSD. Results: The highest mean shear bond strength of composite resin was in group C, while the lowest was in group B. The result of one-way Anova indicated a difference in the shear bond strength of composite resin in the four treatment groups (p &lt; 0.05). An LSD test showed there to be a difference in shear bond strength of composite resin between group A and groups C and D or between group B and groups C and D. There was no difference in shear bond strength of composite resin between group A and group B or between group C and group D. Conclusion: Application frequency of 35% sodium ascorbate affect on shear bond strength of composite resin restoration in bleached dentin by 35% H2O2.

Post-etching cleaning influences the resin shear bond strength to CAD/CAM lithium-disilicate ceramics

Statement of problemThe hydrofluoric acid (HF) is able to promote selective dissolution of the glassy phase in silica-based ceramic. However, the etching leaves insoluble silica-fluoride salts in the surface that affects negatively the bond, affirming the need of a post-etching cleaning.PurposeEvaluate the shear bond strength (SBS) of composite resin to CAD/CAM lithium-disilicate ceramics after different post-etching cleaning and silane treatments.MethodsTwenty-four 2 mm-thick slices of IPS e.max CAD (Ivoclar Vivadent, AG, Schann, Liechtenstein) were crystallized, embedded in acrylic resin, polished and cleaned in an ultrasonic bath. Each specimen was etched with 5% HF for 20 s, rinsed for 60 s, and treatment was completed using surface cleaning and silanization. The cleaning methods were: AW—air/water spray; UB—ultrasonic bath; PA—37% phosphoric acid; and ST—steam cleaning. The cleaned surface received: E—no silane treatment; E/S—silane application for 20 s, air drying for 20 s and hot drying (60 °C) for 20 s; E/S+—silane application for 60 s, air drying for 20 s, hot air drying (60 °C) for 20 s, rinsing with boiling water for 15 s and hot air drying for 20 s. Cylinders of composite resin (n = 12) (Z100, 3M-ESPE, Saint Paul, MN, USA) were bonded using an adhesive resin (Optibond FL adhesive, Kerr Corp, Orange, CA, USA). SBS testing was carried out after 24 h of storage in water. Samples for each post-etching cleaning regimen were analyzed by SEM.ResultsAccording to two-way ANOVA (Bonferroni-corrected post hoc tests, p < 0.05), the SBS was significantly influenced by the post-etching cleaning, with UB yielding the highest SBS (21 MPa for E/S); other post-etching cleaning regimens showed lower SBS values (12–17 MPa). The type of silane application was not significantly different. The SEM analysis showed a cleaner ceramic surface for UB when compared to the other groups.ConclusionsEtching lithium disilicate ceramics following by ultrasonic bath cleaning and regular application of a silane is recommended.

The effect of subpressure on the bond strength of resin to zirconia ceramic.

ObjectiveThis study was conducted to investigate the effect of subpressure on the bond strength of resin to zirconia ceramic. The subpressure would create a pressure gradient which could clean out the bubbles in the adhesives or bonding interface.MethodsTwenty-eight pre-sintered zirconia discs were fabricated. Half of them were polished (group P, n = 14), and the rest were sandblasted (group S, n = 14). After sintered,the surface roughness of the zirconia discs was measured. Then, they were randomly divided into two subgroups (n = 7). The groups were named as follows: PC: P + no additional treatments; PP: P + 0.04 MPa after application of adhesives; SC: S + no additional treatments; and SP: S + 0.04 MPa after application of adhesives. Resin columns were bonded to the zirconia specimens to determine shear bond strength (SBS). The bonding interfaces were observed and the fracture modes were evaluated. Statistical analysis was performed on all data.ResultsThe surface roughness of group S was significantly higher than that of group P (P<0.05). The SBS values were PC = 13.48 ± 0.7 MPa, PP = 15.22 ± 0.8 MPa, SC = 17.23 ± 0.7 MPa and SP = 21.68 ± 1.4 MPa. There were significant differences among the groups (P<0.05). Scanning electron microscopy (SEM) results showed that the adhesives of group SP and PP were closer and denser to the zirconia ceramic than that of group PC and SC. The proportion of the mixed fracture mode significantly increased after adding subpressure (P< 0.05).ConclusionSubpressure can improve the shear bond strength of resin to zirconia ceramics and increase micro-infiltration between the adhesives and the zirconia ceramics, especially on the rough surfaces.

The effect of repeated bonding on the shear bond strength of different resin cements to enamel and dentin.

PURPOSECementation failures of restorations are frequently observed in clinical practice. The purpose of this study is to compare the effect of initial and repeated bonding on the bond strengths of different resin cements to enamel and dentin.MATERIALS AND METHODSNinety human maxillary central incisors were bisected longitudinally. The 180 tooth halves were divided into 2 groups (n = 90) for enamel and dentin bonding. The enamel and dentin groups were further divided into 3 groups (n = 30) for different resin cement types. Composite resin (Filtek Ultimate) cylinders (3 × 3 mm) were prepared and luted to enamel and dentin using Variolink II (Group V), RelyX ARC (Group R), or Panavia F 2.0 (Group P) resin cement. After 24 hours, initial shear bond strengths of the resin cements to enamel and dentin were measured. Using new cylinders, the specimens were de-bonded and re-bonded twice to measure the first and the second bond strengths to enamel and dentin. Failure modes and bonding interfaces were examined. Data were statistically analyzed.RESULTSInitial and repeated bond strengths to enamel were similar for all the groups. The first (15.3 ± 2.2 MPa) and second (10.4 ± 2.2 MPa) bond strengths to dentin were significantly higher in Group V (P<.0001). Second bond strengths of dentin groups were significantly lower than initial and first bond strengths to dentin (P<.0001).CONCLUSIONAll resin cements have similar initial and repeated bond strengths to enamel. Variolink II has the highest first and second bond strength to dentin. Bond strength to dentin decreases after the first re-bonding for all resin cements.

The effect of resin cement type and cleaning method on the shear bond strength of resin cements for recementing restorations.

PURPOSEThis laboratory study assessed the effect of different dentin cleaning procedures on shear bond strength of resin cements for recementing prosthesis.MATERIALS AND METHODS4 × 4 flat surface was prepared on the labial surface of 52 maxillary central incisors. Metal frames (4 × 4 × 1.5 mm) were cast with nickel-chromium alloy. All specimens were randomly divided into 2 groups to be cemented with either Panavia F2.0 (P) or RelyX Ultimate (U) cement. The initial shear bond strength was recorded by Universal Testing Machine at a crosshead speed of 0.5 mm/min. Debonded specimens were randomly allocated into 2 subgroups (n = 13) according to the dentin cleaning procedures for recementation. The residual cement on bonded dentin surfaces was eliminated with either pumice slurry (p) or tungsten carbide bur (c). The restorations were rebonded with the same cement and were subjected to shear test. Data failed the normality test (P < .05), thus were analyzed with Mann Whitney U-test, Wilcoxon signed rank test, and two-way ANOVA after logarithmic transformation (α = .05).RESULTSThe initial shear bond strength of group P was significantly higher than group U (P = .001). Pc and Uc groups presented higher bond strength after recementation compared to the initial bond strength. However, it was significant only in Pc group (P = .034).CONCLUSIONThe specimens recemented with Panavia F2.0 provided higher bond strength than RelyX Ultimate cement. Moreover, a tungsten carbide bur was a more efficient method in removing the residual resin cement and increased the bond strength of Panavia F2.0 cement after recementation.