Self-adhesive Cement Research Articles

Hardness development of self-adhesive resin cement in simulated root canal

To compare the hardness development of dual-cured self-adhesive and universal resin cement in simulated root canal. The light-proof half-cylinder steel slot with one end open were syringed and filled respectively by self-adhesive A (RelyX Unicem), B (BisCem) and universal C (DUOLINK) resin cements, then the open end of slot was irradiated directly by a light unit for 20 s. Specimens were stored in a light-proof box for 0.5 h, Knoop microhardness was measured along the vertical surfaces of specimens from 1 mm to 10mm depth at 1 mm intervals. The same measurements were taken at 24 h and 120 h after irradiation. Data were analyzed by One-way ANOVA. Hardness of each group decreased with the increase of simulated canal depth (P<0.001), however hardness showed no significant change between 5 mm and more depth of group A, between 4 mm and more depth of group B and C. The increase of hardness for each group was more rapid within 0.5 h after irradiation, thereafter the hardness increased gradually to maximum at 24 h. At 120 h after irradiation, hardness of group C was greater than that of other two groups at more than 1 mm depth (P<0.001). Under dual-cured condition, hardness has significant difference between self-adhesive and universal resin cements, however their hardness development is similar.

Inorganic composition and filler particles morphology of conventional and self‐adhesive resin cements by SEM/EDX

The purpose of this study was to characterize the inorganic components and morphology of filler particles of conventional and self-adhesive, dual-curing, resin luting cements. The main components were identified by energy dispersive X-ray spectroscopy microanalysis (EDX), and filler particles were morphologically analyzed by scanning electron microscopy (SEM). Four resin cements were used in this study: two conventional resin cements (RelyX ARC/3M ESPE and Clearfil Esthetic Cement/Kuraray Medical) and two self-adhesive resin cements (RelyX Unicem/3M ESPE and Clearfil SA Luting/Kuraray Medical). The materials (n = 5) were manipulated according to manufacturers' instructions, immersed in organic solvents to eliminate the organic phase and observed under SEM/EDX. Although EDX measurements showed high amount of silicon for all cements, differences in elemental composition of materials tested were identified. RelyX ARC showed spherical and irregular particles, whereas other cements presented only irregular filler shape. In general, self-adhesive cements contained higher filler size than conventional resin luting cements. The differences in inorganic components and filler particles were observed between categories of luting material and among them. All resin cements contain silicon, however, other components varied among them.

Sorption and solubility characteristics of self-adhesive resin cements

ObjectiveThe aim of this in vitro study was to evaluate some sorption characteristics [sorption (S), solubility (SL) and the percentages of mass change (Mg%), solubility (SL%) as well as sorbed liquid (S%)] of self-adhesive resin cements when immersed in distilled water and lactic acid. MethodsA disc-shaped specimen of each self-adhesive resin cements [G-Cem (GC), SmartCem™ 2 (SC2), RelyX™ U100 (R1), RelyX™ Unicem 2 (RU2)] were prepared in a split-Teflon mold and irradiated by an Optilux 501 light cure at 580mW/cm2 for 40s in eight overlapping sections each side. The volume of each specimen was calculated and placed inside a desiccator containing anhydrous calcium chloride, then weighed on an analytical electronic balance. Two independent groups were established according to the immersion media or liquids (distilled water and 0.01M lactic acid) maintained at 37°C for the time intervals: 1, 6, 12, 24, 48 and 168h, where the sorption (S) property (μg/mm3) was calculated. However, the SL, Mg%, SL% and S% were measured after 168h of immersion. The data were statistically analyzed by repeated measures ANOVA, one-way ANOVA and post hoc Tukey's test (p<0.05). ResultsAnalysis of variance revealed highly significant differences between the materials for the sorption and solubility values examined with some exceptions (p<0.05). However, independent samples T-test expressed significant differences of all the sorption values between both water and lactic acid media for the resin cements with some border significances (p>0.05). The highest liquid's sorption was exhibited by GC material after immersion in lactic acid for 168h period followed by SC2 (37.83 and 34.15μg/mm3, respectively), while the lowest sorption was presented by RU2 cement after 1h immersion period in water (3.89μg/mm3). Stereomicroscope showed homogenous surface topography in RU2 and R1 samples, while some striated cracks and microvoids were observed in GC and SC2 materials, respectively. The SL values followed this order: RU2<R1<SC2<GC. SignificanceKnowing the best self-adhesive cement that can provide less sorption and solubility values will help the dentist to choose the most suitable luting material for indirect restorations.

Self-adhesive cements

Self-adhesive cements

1-Year clinical study of indirect resin composite restorations luted with a self-adhesive resin cement: effect of enamel etching

In vitro studies have recommended enamel-etching before luting indirect restorations with self-adhesive resin cement. However, there is no scientific proof that this procedure has any clinical relevance. Thus, the aim of this study was to evaluate the effect of enamel-etching on the marginal quality of indirect composite resin restorations (inlay/onlay) using the self-adhesive cement RelyX Unicem clicker. Forty-two posterior teeth were selected from 25 patients that presented one or two teeth with large restorations in need of replacement. All teeth were prepared by the same operator and impressed with polyvinylsiloxane material. The composite resin restorations were built over plaster casts using the incremental technique with a LED device for light-curing the increments. The inlays/onlays were cemented according to one of the following protocols: 1. Etched group (ETR) - selective enamel phosphoric-acid etching + RelyX Unicem clicker; 2. Non-etched group (NER) - RelyX Unicem clicker alone. Each surface was light-cured for 60 s. Recalls occurred after 1 week (baseline), 6 and 12 months when the teeth were evaluated according to previously established scores (modified USPHS criteria). The clinical analysis showed little or no visible changes in the marginal quality after 1 year, even though a probe could detect all the restorations margins. Statistical analysis (Fisher's exact test, p<0.05) detected no differences between the groups after 12 months. No restorations failed and no secondary caries were found. Enamel acid etching had no clinical relevance on the marginal quality of indirect composite resin restorations luted with RelyX Unicem clicker after 1 year of follow up.

Effect of Er,Cr:YSGG pretreatment on bond strength of fiber posts to root canal dentin using a self-adhesive resin cement

The weak link in the adhesive luting of fiber posts to root canal dentin is at the cement-dentin interface. The aim of the present study was to evaluate the effect of Er,Cr:YSGG laser irradiation on push-out bond strength of fiber posts cemented to root canal dentin using a self-adhesive cement. A total of 30 sound human maxillary central incisors were equally divided into two groups after root canal treatment, decoronation and preparation of the post space. Teeth of group 1 were treated with the Er,Cr:YSGG laser, and teeth of group 2 (control) received no laser treatment. After cementation of fiber posts with Maxcem self-adhesive cement, 3-mm cervical, middle and apical sections were prepared from the roots. Then a push-out test was performed using a universal testing machine at a strain rate of 0.5 mm/min. Data were analyzed using two-way ANOVA and the Bonferroni test. Statistical significance was defined as P < 0.05. There was a significant difference in the mean bond strength values between groups 1 and 2 (P = 0.001), but there were no significant differences between the various root parts (P = 0.14). In addition, the cumulative effects of dentin treatment type and various root parts were not statistically significant (P = 0.41). The mean bond strength in the laser group was significantly higher than in the control group (P = 0.001, post hoc Bonferroni test).The failure mode was evaluated under a stereomicroscope at × 20 magnification.

Adhesion of Indirect MOD Resin Composite Inlays Luted With Self-adhesive and Self-etching Resin Cements

This study investigated the effect of loading on the bond strength to dentin and microleakage of MOD indirect composite restorations bonded with self-adhesive and self-etching resin cements with or without acid etching of the proximal enamel margins. Class II MOD cavities were prepared in 48 molar teeth into dentin and divided into three groups of 16 teeth. Impressions were taken and indirect composite inlays fabricated (Estenia C & B). The enamel margins of the proximal boxes of half the specimens were phosphoric acid etched, and the inlays were cemented with one of three cements (Panavia F 2.0, SA Cement, or Rely X Unicem). After luting, eight teeth in each cement group were mechanically loaded at 2.5 cycles/s for 250,000 cycles. Unloaded teeth acted as controls. Teeth were stored in Rhodamine B solution for 24 hours, sectioned buccolingually at the proximal boxes to examine microleakage using confocal microscopy, and further sectioned for μTBS testing of the resin-dentin interface. Analysis of variance was performed to assess the effect of loading and acid etching on microleakage and bond strength. Acid etching had no effect on microleakage. No significant difference in the dentin bond strengths between the three cements existed after loading. Panavia F 2.0 exhibited a significant reduction in bond strength. With regard to microleakage at the proximal boxes, loading had no effect on dye penetration at the cavity floor. However, at the axial walls, loading had a significant deleterious effect on Panavia F 2.0. No difference in microleakage existed between the three cements at both sites before and after loading. In conclusion, the two tested self-adhesive cements exhibited similar bond strengths before and after loading to the self-etching resin cement. Loading reduced dentin bond strengths and increased microleakage at the resin-dentin interface. However, acid etching of the enamel margins had no significant effect on microleakage in the approximal regions of the bonded inlays.

Leucite-reinforced glass ceramic inlays luted with self-adhesive resin cement: A 2-year in vivo study

ObjectivesAim of the present prospective controlled clinical study was to compare the clinical performances of two different cementation procedures to lute IPS Empress inlays and onlays. MethodsEighty-three IPS Empress restorations (70 class-II inlays, 13 onlays/47 premolars, 36 molars) were placed in 30 patients (19 females/11 males, mean age=39 years). Two cementation procedures were tested: group 1: forty-three restorations were luted with a self-adhesive resin cement (RelyX Unicem, RX, 3M ESPE); group 2: forty restorations were luted with an etch-and-rinse multistep adhesive (Syntac Classic, Ivoclar-Vivadent) and Variolink II low (SV, Ivoclar-Vivadent). All restorations were evaluated after 2 weeks (baseline=1st recall=R1, n=83), 6 months (R2, n=83), 1 year (R3, n=82), and 2 years (R4, n=82) by two independent blinded calibrated examiners using modified USPHS criteria. ResultsFrom R1 to R4, one failure occurred in the SV group (at R2) due to marginal enamel chipping. After 2 years of clinical service (R4), better marginal and tooth integrity (p<0.05) was found in group 2 (SV) compared to the use of the self-adhesive cement (RX, group 1), while no differences were found for all remaining investigated criteria (p>0.05). The absence of enamel in proximal boxes (10% with no enamel and 51% of the restorations with less than 0.5mm enamel width at the bottom of the proximal box) did not affect marginal performance (p>0.05). SignificanceThe self-adhesive resin cement RelyX Unicem showed clinical outcomes similar to a conventional multi-step cementation procedure after 2 years of clinical service for most of the tested criteria.

Effect of smear layer treatment on dentin bond of self-adhesive cements

The purpose of this study was to compare the dentin bond strength of three self-adhesive cements with smear layer pretreatments using a calcium-chelating agent (EDTA) and deproteinizing solution (NaOCl) and to evaluate their interfacial characteristics. Smear layer-covered dentin surfaces were pretreated with EDTA for 60 s, NaOCl for 5 and 15 s, or none. Three self-adhesive cements; Clearfil SA luting (Kuraray Medical), Rely X Unicem clicker (3M ESPE) and Breeze (Pentron) were applied to the dentin surfaces. After 24-h water storage, shear bond strengths to dentin were determined. In addition, nanoleakage evaluation at the interface was performed using FE-SEM and EDS. EDTA-pretreatment significantly improved the bond strength of BR (p<0.05) and NaOCl-pretreatment for 15 s significantly improved the bond strength of RX (p<0.05). On the other hand, for SA, both pretreatments significantly decreased bond strength to dentin (p<0.05). Nanoleakage formation was observed in various amounts at the cement-dentin interfaces.

Clinical and Technical Considerations of Luting Agents for Fixed Prosthodontics

Clinical and Technical Considerations of Luting Agents for Fixed Prosthodontics

Critical Surface Energy of Composite Cement Containing MDP (10-Methacryloyloxydecyl Dihydrogen Phosphate) and Chemical Bonding to Hydroxyapatite

Self-adhesive composite cements are increasingly used for cementing inlays/onlays, intraradicular posts, crowns and laminate veneers. Wider clinical acceptance is driven by simpler and faster handling procedures, much like observed for self-etching adhesives. 10-Methacryloyloxydecyl dihydrogen phosphate (MDP) is a bi-functional monomer incorporated as the reactive ingredient in a contemporary self-adhesive cement. We have examined the surface free energy parameters of this cement and studied the mode of action of the cement on dentine substrate by contact angle measurements to determine the critical surface energy of the cement. Retention of the infrared absorption bands characteristic of the acrylate moieties on the surface of hydroxyapatite particles suggests that MDP contributes to the overall bonding to dentine by forming ionic chemical bonds with surface calcium ions in dentine crystalites.

Microtensile bond strength of self-adhesive luting cements to ceramics.

The purpose of this paper was to compare the bond strengths of the self-adhesive luting cements between ceramics and resin cores and examine their relation to the cement thickness. Three self-adhesive luting cements (Smartcem, Maxcem, and G-CEM) and a resin cement (Panavia F 2.0) for control were used in the paper. The thickness of the cements was controlled in approximately 25, 50, 100, or 200 μm. Each 10 specimens were made according to the manufacturers' instructions and stored in water at 37°C. After 24 hours, microtensile bond strength (μTBS) was measured. There were significant differences in cements. Three self-adhesive cements showed significantly lower μTBSs than control that required both etching and priming before cementation (Tukey, P < 0.05). The cement thickness of 50 or 100 μm tended to induce the highest μTBSs for each self-adhesive luting cements though no difference was found.

Factors affecting the cement–post interface

ObjectivesTo evaluate the effect of different factors on the push-out bond strength of glass fiber posts luted in simulated (standard) root canals using different composite cements. MethodsThree types of glass-fiber root-canal posts with a different matrix, namely an epoxy resin (RelyX post, 3M ESPE), a proprietary composite resin (FRC-Plus post, Ivoclar-Vivadent), and a methacrylate resin (GC post, GC), and three types of composite cements, namely an etch-and-rinse Bis-GMA-based (Variolink II, Ivoclar-Vivadent), a self-etch 10-MDP-based (Clearfil Esthetic Cement, Kuraray) and a self-adhesive (RelyX Unicem, 3M ESPE) cement, were tested. Posts were either left untreated (control), were treated with silane, or coated with silicated alumina particles (Cojet system, 3M ESPE). Posts were inserted up to 9-mm depth into composite CAD-CAM blocks (Paradigm, 3M ESPE) in order to solely test the strength of the cement–post interface, while excluding interference of the cement–dentin interface. After 1-week storage at 37°C, three sections (coronal, middle, apical) of 2-mm thickness were subjected to a push-out bond-strength test. ResultsAll three variables, namely the type of post, the composite cement and the post-surface pre-treatment, were found to significantly affect the push-out bond strength (p<0.001). Regarding the type of post, a significantly lower push-out bond strength was recorded for the FRC-Plus post (Ivoclar-Vivadent); regarding the composite cement, a significantly higher push-out bond strength was recorded for the self-adhesive cement Unicem (3M ESPE); and regarding the post-surface treatment, a significantly higher push-out bond strength was recorded when the post-surface was beforehand subjected to a Cojet (3M ESPE) combined sandblasting/silicatization surface pre-treatment. Many interactions between these three variables were found to be significant as well (p<0.001). Finally, the push-out bond strength was found to significantly reduce with depth from coronal to apical. SignificanceLaboratory testing revealed that different variables like the type of post, the composite cement and the post-surface pre-treatment may influence the cement–post interface, making clear guidelines for routine clinical practice hard to define. Further long-term durability testing may help to clarify, and should therefore be encouraged.

Push-out bond strength of quartz fiber posts to root canal dentin using total-etch and self-adhesive resin cements

Objectives: Several adhesive systems are available for cementation of fibre posts into the root canal. The aim of the present study was to investigate the push-out bond strengths of quartz fibre posts to root dentin with the use of different total-etch and self-adhesive resin cements. Study Design: Ninety single-rooted human premolars were endodontically treated and standardized post-spaces were prepared. Fibre posts were cemented with different luting agents: total-etch (Nexus NX3, Duo-Link, and RelyX ARC) and self-adhesive resin cements (Maxcem Elite, BisCem, and RelyX Unicem). Three post/dentin sections (coronal, middle and apical) were obtained from each specimen, and push-out bond strength test was performed in each section at a cross-head speed of 0.5 mm/min. Data was analyzed with two-factor and one-way analysis of variance and a post-hoc Tukey test at a significance level of p < 0.05. Results: Cement type, canal region, and their interaction significantly influenced bond strength. Significantly higher bond strength values were observed in the apical region of self-adhesive cements. Only Duo-Link and RelyX ARC cements resulted in homogeneous bond strengths. Conclusions: Cementation of quartz fibre posts using self-adhesive cements provided higher push-out bond strengths especially in the apical region, while total-etch cements resulted in more uniform bond strengths in different regions of the root canal. Key words: Push-out bond strength; quartz fibre post; total-etch resin cement; self-adhesive resin cement.

Bonding effectiveness of a self-adhesive resin-based luting cement to dentin after provisional cement contamination.

To evaluate the influence of provisional luting cements on the bonding performance of a resin-based self-adhesive luting cement to dentin vs that of currently used resin-based luting agents with different adhesion strategies. Forty-five prepared human molars were randomly and equally divided into three main groups according to the type of provisional luting cement applied: eugenol-containing provisional cement (Temp Bond, Kerr), eugenol-free provisional cement (Temp Bond NE, Kerr), and control where the provisionalization step was omitted. Each group was further subdivided into 3 groups based on the category of adhesive systems/ luting materials used: a two-step etch-and-rinse system (Single Bond/RelyX ARC; 3M ESPE) (RX), a two-step self-etching system (Clearfil Liner Bond 2V/ Panavia F; Kuraray) (PF), and a self-adhesive luting cement (Rely X Unicem; 3M ESPE) (RU). Finally, 9 groups of 5 teeth each were prepared for the microtensile test. Two-way analysis of variance (ANOVA) and post-hoc Bonferroni tests revealed that definitive luting cement, provisional luting cement, and the interactions of these two factors had significant influences on dentin bond strength. The highest bond strength was obtained for PF (32.05 MPa), followed by RX (26.57 MPa) and RU (16.56 MPa) for the controls. Contamination with either eugenol-containing or eugenol-free provisional cement significantly decreased the bonding effectiveness of RX (19.08 and 19.69 MPa, respectively) and PF (14.21 and 16.67 MPa respectively) to dentin (p < 0.05). RU showed comparable bond strength values before and after provisional cement (13.93 and 14.49 MPa, respectively) application (p > 0.05). Eugenol in provisional luting cement did not produce material-related alterations in the bonding performance of the resin luting cements tested (p > 0.05). Based on these results, the self-adhesive cement which was not influenced by the provisional cement application may be promising. However, long-term laboratory and clinical performance of this cement needs to be assessed before recommending it as an alternative to the technically more demanding approaches. Moreover, an effective surface cleansing procedure is critical to achieve a successful bond between the contaminated dentin and luting cement.

Influence of temporary cement contamination on the surface free energy and dentine bond strength of self-adhesive cements

Objectives The surface free energy and dentine bond strength of self-adhesive cements were examined after the removal of temporary cements. Methods The labial dentine surfaces of bovine mandibular incisors were wet ground with #600-grit SiC paper. Acrylic resin blocks were luted to the prepared dentine surfaces using HY Bond Temporary Cement Hard (HY), IP Temp Cement (IP), Fuji TEMP (FT) or Freegenol Temporary Cement (TC), and stored for 1 week. After removal of the temporary cements with an ultrasonic tip, the contact angle values of five specimens per test group were determined for the three test liquids, and the surface-energy parameters of the dentine surfaces were calculated. The dentine bond strengths of the self-adhesive cements were measured after removal of the temporary cements in a shear mode at a crosshead speed of 1.0 mm/min. The data were subjected to one-way analysis of variance (ANOVA) followed by Tukey's HSD test. Results For all surfaces, the value of the estimated surface tension component γ S d (dispersion) was relatively constant at 41.7–43.3 mJ m −2. After removal of the temporary cements, the value of the γ S h (hydrogen-bonding) component decreased, particularly with FT and TC. The dentine bond strength of the self-adhesive cements was significantly higher for those without temporary cement contamination (8.2–10.6 MPa) than for those with temporary cement contamination (4.3–7.1 MPa). Conclusions The γ S values decreased due to the decrease of γ S h values for the temporary cement-contaminated dentine. Contamination with temporary cements led to lower dentine bond strength. Clinical significance The presence of temporary cement interferes with the bonding performance of self-adhesive cements to dentine. Care should be taken in the methods of removal of temporary cement when using self-adhesive cements.

Bond Strength and Interfacial Micromorphology of Etch‐and‐Rinse and Self‐Adhesive Resin Cements to Dentin

To evaluate the microtensile bond strength and interfacial micromorphology of indirect composite restorations to dentin using three commercial resin cements after 24 hours and 30 days of water storage. The medium dentin of third human molars was exposed (N = 30, n = 10 per group). Three commercial resin cements were used to cement indirect resin composite restorations to dentin: the auto-cured C&B Cement/All Bond 2, the dual-cured RelyX ARC/Adper Single Bond 2, and the self-adhesive dual-cured RelyX Unicem. Teeth were sectioned after water storage at 37°C (24 hours and 30 days) to obtain beams with a bonded area of 0.8 mm(2) . The specimens were tested in a universal testing machine at a 0.5 mm/min crosshead speed. Scanning electron microscopic fractographic and interfacial micromorphology analyses were performed. Data were analyzed using two-way ANOVA and Tukey's test (α= 0.05). Mean bond strength (MPa) after 24 hours: C&B Cement 19.5 ± 3.8, RelyX ARC 40.8 ± 9.4, RelyX Unicem 31.3 ± 7.4; after 30 days: C&B Cement 24.5 ± 5.1, RelyX ARC 44.2 ± 8.5, RelyX Unicem 28.3 ± 7.1. The mean bond strengths of both dual-cure cements were significantly higher than that obtained with C&B Cement after 24 hours. A significant increase in the bond strength of C&B Cement was verified after 30 days, reaching values statistically equivalent to those produced by RelyX Unicem and RelyX ARC. The self-adhesive cement preserved the same level of bond strength after 30 days. Fractographic analysis revealed a prevalence of cohesive fractures in the hybrid layer for C&B Cement, mixed (cohesive in the cement, hybrid layer, and adhesive) for RelyX ARC, and cohesive in the cement for RelyX Unicem. No distinguishable hybrid layer or resin tags were observed in the interaction of RelyX Unicem with dentin. The particular interaction of each cement with dentin results in specific bond strength and failure patterns that varied among groups in both evaluation times. Even though the self-adhesive cement tested exhibited no authentic hybrid layer, it was able to promote reliable adhesion with the underlying dentin.

Influence of resin cement and post configuration on bond strength to root dentine

To evaluate the effect of luting agent and fibreglass post design on bond strength to root dentine at different depths within the canal. Ninety single-rooted teeth were root filled and prepared to receive either a parallel-sided and serrated fibreglass post (Reforpost no. 2) or a tapered and smooth fibreglass post (Exato Cônico). The posts were cemented with the following resin cements: dual-cured resin cement (Rely X ARC), two self-adhesive resin cements (Rely X Unicem and MaxCem) and a self-cured resin cement (Cement-Post). The roots were cross-sectioned to obtain two 1-mm-thick discs for each cervical, middle and apical third of the prepared root portion. The posts were submitted to a micropush-out test at a speed of 0.5 mm min(-1), and the bond strength values (MPa) were submitted to anova in a split-plot arrangement and Tukey's test (P < 0.05). The RelyX Unicem demonstrated significantly higher bond strength values (P < 0.001) along the root dentine. The RelyX ARC and Cement-Post had similar bond strength values in the cervical third; however, the bond strength decreased significantly (P < 0.001) in an apical direction for the RelyX ARC. Significantly lower bond strength values (P < 0.001), irrespective of canal region, were found for MaxCem cement. The bond strength was similar for both post configurations irrespective of the resin cement and canal region. The retention of glass fibre posts remained unaffected by surface roughness but was influenced by resin cement type. The self-adhesive cement RelyX Unicem yielded a significantly greater (P < 0.001) bond strength value when cementing the fibreglass posts.

Resin Bond Strength to Alumina Coated Ce-TZP/Al&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; Dental Ceramic

The aim of this study was to functionalize the surface of Ce-TZP/Al2O3 dental ceramic with a nano-structured alumina coating to improve resin bonding. A total of 40 densely sintered disc-shaped specimens (15.5 + 0.03 mm in diameter and 2.6 + 0.03 mm thick) were produced from commercially available NANOZIR blocks and randomly divided into 2 groups of 20. Half of the discs in each group received an alumina coating that was fabricated by exploiting the hydrolysis of aluminum nitride (AlN) powder. The coating was characterized using scanning electron microscopy (SEM). The shear bond strength of the self-adhesive luting cement G-cem was then studied for the coated and uncoated surfaces before and after thermocycling (TC). The SEM analysis revealed that the application of an alumina coating to Ce-TZP/Al2O3 ceramics created a highly retentive surface for resin penetration. The resin bond strength to the coated groups was significantly higher than to the uncoated groups, both before and after TC (p ≤ 0,05).

Influence of the Curing Mode on Fluoride Ion Release of Self-adhesive Resin Luting Cements in Water or During pH-Cycling Regimen

This study evaluated the effects of curing modes and storage conditions on fluoride release of resin cements. In phase 1, the cumulative fluoride release rate from samples of the resin cements (Panavia F 2.0, RelyX Unicem, MaxCem, and BisCem) was quantified after 15 days storage in water (n=4). In phase 2, the fluoride release profiles from the same materials were analyzed during pH cycling (n=4). In this second phase, fluoride was measured at specific times (one, two, three, five, eight, and 15 days). Disk-shaped specimens were prepared (10 mm × 0.5 mm), and the materials were either light activated or allowed to autopolymerize. For both phases, the fluoride release was measured using a fluoride ion-specific electrode. The fluoride release in water was not affected by the curing mode of RelyX Unicem and Maxcem resin cements. Panavia F. 2.0 and BisCem resin cements, either light cured or autopolymerized modes, released higher amounts of fluoride in water than the other self-adhesive cements. In phase 2, the concentration of fluoride released decreased from the first day of pH cycling until the 15th day for all resin cements, for both curing modes, regardless of the storage solution used (demineralizing/remineralizing). The fluoride release rate during pH cycling by Panavia F 2.0 and MaxCem was not affected by the curing mode. The effect of the curing mode on fluoride ion release in water or during pH cycling was product dependent.