Type Of Resin Cement Research Articles

Two-step vs. one-step conditioning systems and adhesive interface of glass ceramic surface and resin systems

The effect of two-step and one-step ceramic surface conditioning/priming, and subjecting to exposure with boiling water on adhesion strength of resin cements was evaluated. Rectangular shaped specimens were cut from CAD blocks of E-max (Ivoclar Vivadent) and Mark II (VITA Zahnfabrik) and randomly assigned to two main study groups. Group one specimens’ surfaces were conditioned using the two-step conditioning/priming procedure and group two specimens were treated using the one-step conditioning/priming system. After treating, 3 mm thick resin cement layer was applied onto the surface using a split stainless steel mold. Each group was further divided into four subgroups (n = 10) depending on type of resin cement applied and subjecting to exposure in boiling water. Adhesion strength of all the specimens was measured using the universal material testing machine, results were tabulated and subjected to statistical analysis at a significance level of p < 0.05. Adhesive resin showed higher values of 22.05 and 18.65 MPa with E-max and Mark II respectively, and resin composites showed 18.13 and 15.13 MPa with E-max and Mark II respectively, when two-step conditioning system was employed. Majority of the adhesive resin specimens showed cohesive failure in cement. Subjecting the specimens to exposure in boiling water for 24 h not only showed adhesive failure but also significantly reduced adhesion strength of adhesive resin and resin composite. The significance of the study is that, the traditional two-step ceramic surface conditioning is more effective than the one-step conditioning and unfilled adhesive resin provides better adhesion strength.

Effect of different surface treatments on shear bond strength of zirconia bonded to dentin with two resin luting cements

All-ceramic materials, especially silica-based lithium di-silicate and non-silicatebasedZirconia have become a topic of interest in the field of dentistry. It is stilldifficult to achieve a strong and durable resin-ceramic adhesion, especially resin-Zirconia bonding, focusing on the latest resin bonding techniques including surfacetreatment, priming and cementation.The purposes of this study was to evaluate the effect of different surfacetreatments on shear bond strength of zirconia bonded to dentin with two resin lutingcements.A total 60 zirconia discs 3mm thickness and 6 mm diameter subjected tothree types of surface treatments,irradiated with CO2 laser,etched with hydrofluoricacid, sandblasted+ceramic primer application,then bonded to dentin with two types ofresin cement (variolinkII and Dentocem). Shear bond strength was measured and thetype of failures were determined. The data were statistically analyzed by one-wayanalysis of variance and Independent T-test. The results of this study showed that thegroups which were sandblasted treated with ceramic primer produced highest shearbond strength followed by hydrofluoric etched groups and CO2 laser irradiated groupsshowed the lowest bond strength. Dentocem resin cement showed better bonding thanvariolink II.The failures were either adhesive (between discs and cement)orcohesive(cements on both disc and dentin).As a conclusion the bonding of Zirconiacan be improved by the different surface treatments especially by sandblastingceramic primer . Dentocem resin cement showed higher shear bond strength thanvariolinkII so promoted better adhesion between dentin and zirconia..

The effect of Z-primer on the shear bond strength of zirconia ceramic to dentin: in vitro.

BackgroundOne of the major limitations of zirconia ceramic is the difficulty to adhere to dental. Said adhesion improves the marginal sealing of the restoration, minimizing microleakage. According to the limitation of zirconia ceramic bonding, zirconia primer enhances bond strengths to Zirconia, Alumina and Metal substrates. Purpose: the aim of the current study was to determine effect of Z-primer on the shear bond strength of zirconia ceramic to dentin.Material and Methods28 newly extracted intact premolars and divided into 4 groups (n=7). In group 1, resin-based (Duo-link; Bisco, Schaumburg, IL) cement was used without applying Z-primer. In group 2, resin-based (Duo-link; Bisco, Schaumburg, IL) cement was used with applying Z-primer. In group 3, resin-based cement (Panavia F2; Kurary, Japan) was used without Z-primer. In group 4, resin- based cement (Panavia F2) with Z-primer was used. Zirconia ceramic blocks (4×4×2mm) without sandblasting were applied onto the surface of dentin then cured from 3 dimensions for 20S. Shear bond strength test was carried out after 24h. Stereo microscope was used to evaluate the zirconia ceramic and dentin topography and failure mode.ResultsAccording to the data, significant difference detected on after application of the Z-primer compared to the other groups (p<0.001). No significant difference detected between 2 types of resin cements (p>0.05). However, the highest SBS observed in second group (Duo-link(+)Zprimer) while lowest detected in first group (Duo-link(-)Zprimer).ConclusionsThese results suggested application of the Z-primer increased shear bond strength between zirconia ceramic and dentin. Key words:Flexural strength, monolithic zirconia, sintering temperature, sintered-holding time.

Effect of adhesive resin cements on bond strength of ceramic core materials to dentin.

The aim of the present study was to evaluate the effects of self-etch and self-adhesive resin cements on the shear bond strength of ceramic core materials bonded to dentin. Extracted, caries-free, human central maxillary incisor teeth were selected, and the vestibule surfaces were cut flat to obtain dentin surfaces. Ceramic core materials (IPS e.max Press and Prettau Zirconia) were luted to the dentin surfaces using three self-etch adhesive systems (Duo-Link, Panavia F 2.0, and RelyX Ultimate Clicker) and two self-adhesive resin systems (RelyX U200 Automix and Maxcem Elite). A shear bond strength test was performed using a universal testing machine. Failure modes were observed under a stereomicroscope, and bonding interfaces between the adhesive resin cements and the teeth were evaluated with a scanning electron microscope. Data were analyzed with Student's t-test and one-way analysis of variance followed by Tukey's test (α = 0.05). The type of adhesive resin cement significantly affected the shear bond strengths of ceramic core materials bonded to dentin (P < 0.05). Significant differences were noted between the ceramic core materials when the specimens were luted with self-adhesive resin cements (P < 0.05). The specimens luted with RelyX Ultimate Clicker had the highest shear bond strengths. The self-etch adhesive resin cements exhibited better shear bond strength than the self-adhesive resin cements, except for Panavia cement in the IPS e.max Press group. However, shear bond strengths of the self-adhesive resin cements were dependent on the nature of the ceramic core materials.

Effect of Fiber Post Cementation Timing on the Bond Strength of Resin Cements in Epoxy Resin-Obturated Canals.

This study evaluated the influence of timing after endodontic treatment and type of resin cement used on the bond strength of fiber posts to epoxy resin-obturated canals. A total of 80 bovine incisor roots were divided into four groups (n = 20). Glass fiber posts were cemented at two different times, immediately or 7 days after endodontic treatment, using either a dual-curing resin cement (RelyX ARC, 3M ESPE) or a self-adhesive resin cement (RelyX U200, 3M ESPE). Following post cementation, the samples were cross-sectioned into slices containing root dentin, cement, and fiber post at the cervical, mid, and apical root thirds. The push-out test was performed on a universal testing machine. Three-way analysis of variance for randomized blocks showed no significant effect within the triple interaction (P = .394) or between the double interactions cement-timing (P = .395), cement-root thirds (P = .996), and timing-root thirds (P = .331). The main factor cement revealed a significant effect, showing that regardless of the timing and root third, RelyX ARC provided significantly higher bond strength values than U200. Regardless of root third and timing, the dual-curing resin cement showed higher bond strength to root dentin when the canals were filled with epoxy resin-based cement.

The Effect of Resin Cement Type and Thermomechanical Aging on the Retentive Strength of Custom Zirconia Abutments Bonded to Titanium Inserts.

The purpose of this study was to investigate the effect of resin cement type on the retentive strength of custom zirconia abutments bonded to titanium inserts. Sixty implant (4.3 mm diameter and 11.5 mm length) and custom zirconia abutment (15 mm height and 2 mm wall thickness) pairs were used to form six groups (n = 10 each). Three different resin cements were used to bond the zirconia abutments and titanium inserts: Panavia F 2.0, Zirconite, and Multilink Hybrid Abutment. Control groups and thermomechanically aged groups were formed. Specimens were subjected to tensile test to failure, and the retention values were analyzed by two-way analysis of variance (ANOVA). Two-way ANOVA showed a significant effect of the cement type and thermomechanical aging (P < .05). Regardless of the cement, control groups showed significantly (P < .05) higher retentive strength than the thermomechanically aged groups. Comparing the resin cements, the retentive strength of Zirconite, aged or not, was higher than that of Panavia F 2.0 and Multilink Hybrid Abutment; no significant differences between the latter two cements were found. In the Zirconite group, adhesive failure occurred mostly between the titanium and the resin cement. In the Panavia F 2.0 and Multilink Hybrid Abutment groups, adhesive failure between the zirconia and the resin cement was observed. Resin cement type had an effect on the retentive strength of custom zirconia abutments bonded to titanium inserts. Thermomechanical aging had a negative effect on the retentive strength. Zirconite adhesively bonded to the zirconia surface of the custom abutment. Differences were noted in adhesive failure types among the cements.

Microtensile bond strength and scanning electron microscopic evaluation of zirconia bonded to dentin using two self-adhesive resin cements; effect of airborne abrasion and aging

Aim of the studyThis in vitro study was conducted to evaluate the microtensile bond strength (μTBS) of surface treated zirconia bonded to dentin specimens using two aged contemporary dual cured self-adhesive resin cements. Materials and methodsSixty cuboidal-shaped zirconia ceramic specimens were obtained using CAD/CAM system. Specimens were divided into two equal main groups; 30 specimens each, gp A in which specimens did not receive any further surface treatment & gp B in which only one surface of each specimen was airborne abraded. Each group was then divided into two equal groups; 15 each, according to the type of adhesive resin cement used for bonding zirconia specimens to ground flat dentine surfaces; RelyX™ U200 (cement I) and Multilink® Speed (cement II). The assemblies were further subdivided into 3 equal subgroups; 5 assemblies each, according to aging protocol. The aging protocols were storage in distilled water for 1 day, for 7 days without thermocycling and for 7dayes followed by thermocycling; subgroups 1, 2 and 3 respectively. After aging, the assemblies were sectioned into beams approximately 1 mm2 in cross section resulting in 25 beams for each subgroup; 20 of them were selected for μTBS (n = 20) and 5 were kept for SEM examination. ResultsGroup B showed statistically significantly higher mean micro tensile bond strength value than group A. The type of cement had statistically insignificant effect on mean micro tensile bond strength. Thermocycling significantly reduced μTBS of both cements bonded to untreated zirconia ceramic; IA3 and IIA3 subgroups.For SEM, cement I showed gaps at its interface with zirconia groups A and B regardless of aging protocol. Cement II showed only gaps at its interface with zirconia ceramic group A only but good adaptation appeared at its interface with zirconia ceramic group B for aged for 1 day (subgroup IIB1) and 7 days without thermocycling (subgroup IIB2). However, cement II bonding air abraded zirconia ceramic followed by thermocycling (subgroup IIB3) showed both gap free as well as gap containing areas at high magnification only. ConclusionsAirborne abrasion-surface treatment of zirconia significantly enhanced the μTBS of both cements adhered to dentin while aging had an adverse effect. MS showed higher insignificant μTBS.

Investigation the Effect of Restorations Fabricated with CAD/CAM Technology, the Heat-Press Technique, and Type of Resin Cement on Marginal and Internal Adaptation of All Ceramic Crowns

Statement of the problem; the use of pressable and CAD/CAM ceramics have been lately frequently used in fixed prosthodontics. However, information about their marginal fit and internal adaptation are is little.Purpose: Marginal adaptation and internal adaptation are an important factor affecting the longevity of all ceramic restorations, so the purpose of the study was to evaluate the effect of restorations fabricated with CAD/CAM technology, the heat-press technique ceramic and luting agent on the Marginal Fit and Internal Adaptation of all Ceramic crowns.Materials & methods: A total of 20 mandibular Second premolars teeth were used in this study and divided into two groups according to technique of fabrication of ceramic crowns as follow: Machinable ceramics (M). IPS E-max CAD blocks have used for fabrication of ceramic crowns. (n=10), Pressable ceramics (P). IPS E-max press ingots have used for fabrication of ceramic crowns. (n=10).Each group is divided into two subgroups according to the type of resin cement used as follow: Group T: Ceramic crowns are cemented with total etch Cement-it resin cement (n=5). Group S: Ceramic crowns are cemented with Rely-x self-adhesive resin cement (n=5). A silicone replica was obtained to measure marginal and internal adaptation of each all-ceramic crown before luting, and they were sectioned vertically in mesiodistal direction. Marginal and internal adaptations were measured using computerized light microscope at 100 × magnification. Data were presented as mean and standard deviation (SD) values. Regression model with repeated measures Analysis of Variance two ways (ANOVA) was used in testing significance for the effect of ceramic type and cement type.Results: related to marginal gap, it was found that press group recorded statistically significant (P 0.05) higher (54.77± 0.8 μm) than total etch cement (50.3± 5.88 μm).while related to internal adaptation, totally it was found that CAD group recorded statistically significant (P<0.05) higher internal gap mean value (87.45 ± 15.4 μm) than press group (36.64± 5.15 μm) and it was found that internal gap mean value of total etch cement was statistically significant (P<0.05) higher (67.24± 11.14 μm) than self-adhesive cement (56.85± 9.4 μm).Conclusion: Within the limitation of this study, The CAD group recorded statistically significant high vertical marginal fit than press group. The cement type has no effect on the marginal fit. The press group recorded statistically significant high internal fit than CAD group.

INVESTIGATION THE EFFECT OF RESTORATIONS FABRICATED WITH CAD/CAM TECHNOLOGY, THE HEAT-PRESS TECHNIQUE, AND TYPE OF RESIN CEMENT ON MARGINAL AND INTERNAL ADAPTATION OF ALL CERAMIC CROWNS

Statement of the problem; the use of pressable and CAD/CAM ceramics have been lately frequently used in fixed prosthodontics. However, information about their marginal fit and internal adaptation are is little.Purpose: Marginal adaptation and internal adaptation are an important factor affecting the longevity of all ceramic restorations, so the purpose of the study was to evaluate the effect of restorations fabricated with CAD/CAM technology, the heat-press technique ceramic and luting agent on the Marginal Fit and Internal Adaptation of all Ceramic crowns.Materials & methods: A total of 20 mandibular Second premolars teeth were used in this study and divided into two groups according to technique of fabrication of ceramic crowns as follow: Machinable ceramics (M). IPS E-max CAD blocks have used for fabrication of ceramic crowns. (n=10), Pressable ceramics (P). IPS E-max press ingots have used for fabrication of ceramic crowns. (n=10).Each group is divided into two subgroups according to the type of resin cement used as follow: Group T: Ceramic crowns are cemented with total etch Cement-it resin cement (n=5). Group S: Ceramic crowns are cemented with Rely-x self-adhesive resin cement (n=5). A silicone replica was obtained to measure marginal and internal adaptation of each all-ceramic crown before luting, and they were sectioned vertically in mesiodistal direction. Marginal and internal adaptations were measured using computerized light microscope at 100 × magnification. Data were presented as mean and standard deviation (SD) values. Regression model with repeated measures Analysis of Variance two ways (ANOVA) was used in testing significance for the effect of ceramic type and cement type.Results: related to marginal gap, it was found that press group recorded statistically significant (P 0.05) higher (54.77± 0.8 μm) than total etch cement (50.3± 5.88 μm).while related to internal adaptation, totally it was found that CAD group recorded statistically significant (P<0.05) higher internal gap mean value (87.45 ± 15.4 μm) than press group (36.64± 5.15 μm) and it was found that internal gap mean value of total etch cement was statistically significant (P<0.05) higher (67.24± 11.14 μm) than self-adhesive cement (56.85± 9.4 μm).Conclusion: Within the limitation of this study, The CAD group recorded statistically significant high vertical marginal fit than press group. The cement type has no effect on the marginal fit. The press group recorded statistically significant high internal fit than CAD group.

The effect of curing conditions on the dentin bond strength of two dual-cure resin cements

PurposeThe purpose of this study was to determine the effect of the curing condition (i.e., the curing mode and restoration thickness) on the tensile bond strength of a dual-cure resin cement applied to dentin. MethodsIndirect composite resin disks (1, 2, and 3mm in thickness) were prepared. The irradiance of a halogen light curing unit through each disk was measured by a curing radiometer. A measurement was also taken for the condition with no disk. Following this, two dual-cure resin cements, Panavia F2.0 and Panavia V5, were polymerized in either dual-cure mode or self-cure mode to bond the composite resin disk to the flat dentin surface. The specimens were sectioned and subjected to a microtensile bond strength (μTBS) test after 24h of water storage. The data were statistically analyzed by two-way ANOVA followed with multiple comparisons by post-hoc Tukey’s test (α=0.05). ResultsThe irradiance values [mW/cm2] measured through indirect composite resin disks were 600 (0mm), 200 (1mm), 90 (2mm), and not detected (3mm). Two-way ANOVA indicated that both the curing condition and the type of resin cement affected the μTBS (p<0.001). The μTBS results for Panavia V5 bonded to dentin were significantly higher than those of Panavia F2.0 bonded to dentin (p<0.05). ConclusionsThe curing condition affected the tensile bond strength of the dual-cure resin cements to dentin. A newly developed resin cement, Panavia V5, showed higher dentin bonding than Panavia F2.0 in both dual- and self-cure modes.

EFFECT OF DIFFERENT SURFACE TREATMENTS AND RESIN TYPES ON BONDING TO TRANSLUCENT ZIRCONIA

Purpose: This in vitro study measured the adhesive properties of 10-MDP and MPE containing resin cements, using two types of zirconia surface treatments; selective infiltration etching(SIE) and airborne particle abrasion (APA) to translucent zirconia (3M, ESPE) .Statement of Problem: Due to translucent zirconia modified composition (alumina content reduced to tenth of its weight) bonding strength to different resin cements after different surface treatments should be investigated adequately . Materials and Methods:Sixty sintered Lava plus high translucency disks(3M,ESPE)were randomly divided into three study groups according to their surface treatment: (a) polished surface (control group); (b) air borne particle abraded (grit blasted) with 50 µm aluminum trioxide (APA); and (c) selective infiltration etching (SIE). Zirconia disks (15x2mm) were then bonded to 60 composite resin disks (8x4mm) using two different resin composite cements (Clearfil SA and Rely X). Resin-zirconia adhesion strength was evaluated using the microshear bond strength test (MSBS) after 24 hour of storage in deionized water at 37˚C. One way ANOVA and Scheffe s post-hoc tests were used to analyze the data (p<0.001). Then fractured samples were studied under SEM and classified according to failure pattern.Results: Different types of resin cement and surface treatment significantly influenced the MSBS (P<0.001). The highest mean MSBS values were recorded with MDP containing resin cement (Clearfil SA) in both SIE (26.18 ±1.12 MPa) and APA (21.67±1.34) groups. Bond strength values were reduced significantly in control group when using the two types of cements. Regarding failure pattern, MDP groups showed cohesive and MPE and control groups showed adhesive type.Conclusion: SIE and APA in combination with 10-MDP containing resin cement established a strong durable bond to zirconia substrates than MPE groups. SIE and APA showed significant higher bond strength values than control groups.

Evaluation of Effect of Zirconia Surface Treatment, Using Plasma of Argon and Silane, on the Shear Bond Strength of Two Composite Resin Cements.

Yttria stabilised tetragonal zirconia opens new vistas for all ceramic restoration by the mechanism of transformation toughening, making it much stronger compared to all other ceramic materials. Currently, it is the most recent core material for all ceramic fixed partial dentures due to its ability to withstand high simulated masticatory loads. Problems which have been reported with zirconia restorations involve the core cement interface leading to loss of retention of the prosthesis. Different reasons which have been reported for the same include the lack of adhesion between zirconia and commonly used cements due to absence of silica phase which makes zirconia not etchable. In addition, the hydrophobic nature of zirconia causes low wettability of zirconia surface by the adhesive cements which are commonly used. The purpose of this in vitro study was to compare and evaluate the effect of two pre-treatments of zirconia, using plasma of argon and silane, on the shear bond strength values of two composite resin cements to zirconia and to evaluate the failure pattern of the debonded areas using stereomicroscopic analysis. Sixty zirconia discs (10 mm×2 mm) were randomly divided into three groups (n=20), following surface treatment, with airborne particle abrasion, using 110 µm Al2O3: Group I (control), Group II (plasma of argon cleaning), and Group III (application of silane primer). Each group had two subgroups based on the type of resin cement used for bonding: subgroup A; Rely X Ultimate (3M ESPE) and subgroup B; Panavia F (Kuraray). In subgroup A, Rely X universal silane primer and in subgroup B Clearfil ceramic primer was used. Shear bond strengths were determined after water storage for one day and thermocycling for 5000 cycles. Data (megapascal) were analyzed using ANOVA and Bonferroni test. Specimens were subjected to stereomicroscopic analysis, for evaluation of failure pattern. Group III produced the highest shear bond strength followed by Group II and Group I. Subgroup A showed higher shear bond strength than Subgroup B. Stereomicroscopic analysis showed cohesive failure in Group III, while in Group I adhesive failure was seen. Silane primer application caused maximum increase in shear bond strength due to increased wettability. Argon plasma treatment was less effective in comparison to silane treatment. Air abrasion when used alone resulted in lower bond strength values, thereby making it necessary to use a combination of surface treatments. Rely X Ultimate cement was superior to Panavia F in terms of adhesive bonding to zirconia.

Fracture Strength and Retention of All-Ceramic Endocrowns Luted Using Two Different Resin Cements

Purpose: The purpose of this in vitro study was to evaluate and compare the fracture resistance and retention of CAD/CAM endocrowns and conventional glass fiber post supported crowns. Materials and Methods: Sixty-four (N=64) sound mandibular molars were endodontically treated and randomly assigned into 2 groups (n=32 each) according to the type of restoration constructed; Group (E): Endodontically treated teeth restored with IPS e.max CAD, lithium disilicate based, endocrowns and Group (P): Endodontically treated teeth restored with glass-fiber posts, composite cores and IPS e. max CAD crowns. Samples of each group were further subdivided into 2 subgroups (n=16 each) according to the type of adhesive resin cement used. the samples were thermocycled (2000 cycle, between 5oC-55oC). Samples were mountedin a universal testing machine and loaded to failure at a crosshead speed of 1.0 mm / min. The failure loads were recorded. Data were analyzed using one-way analysis of variance (ANOVA) and Tukey’s post hoc significance difference tests. Differences were considered significant at P<0.05. The pull-out test was performed on a universal testing machine and the values obtained were statistically analyzed by analysis of variance using one-way analysis of variance (ANOVA)) and multiple comparison test of Tukey, with level of significance at P<0.05. Results: Statistical analysis using twowayanalysis of variance (ANOVA) test revealed no statistically significant difference in failure load among the four tested subgroups (at P< 0.05). Endocrowns recorded statistically significant mean higher fracture load values (1729.91N±407.9) compared to post retained crowns, (1435.84±405.2). Statistical analysis using two ways analysis of variance (ANOVA) test revealed a statistically significant difference in debonding load among the four tested subgroups (at P<0.05). Tukey’s post hoc test revealed a significant difference between each two subgroups. The highest mean debonding loadwas recorded in the subgroup (PR) (96.98N±4.47), whereas the least value was recorded in the subgroup (EM) (49.48N±3.81). Conclusions: lithium disilicate based endocrown restorations increase the fracture resistance of endodontically treated molars compared to conventional crowns associated with glass fiber posts and resin composite filling cores.

Influence of nano-structured alumina coating on shear bond strength between Y-TZP ceramic and various dual-cured resin cements.

PURPOSEThe purpose of this study was to evaluate the effect of nano-structured alumina surface coating on shear bond strength between Y-TZP ceramic and various dual-cured resin cements.MATERIALS AND METHODSA total of 90 disk-shaped zirconia specimens (HASS CO., Gangneung, Korea) were divided into three groups by surface treatment method: (1) airborne particle abrasion, (2) tribochemicalsilica coating, and (3) nano-structured alumina coating. Each group was categorized into three subgroups of ten specimens and bonded with three different types of dual-cured resin cements. After thermocycling, shear bond strength was measured and failure modes were observed through FE-SEM. Two-way ANOVA and the Tukey's HSD test were performed to determine the effects of surface treatment method and type of cement on bond strength (P<.05). To confirm the correlation of surface treatment and failure mode, the Chi-square test was used.RESULTSGroups treated with the nanostructured alumina coating showed significantly higher shear bond strength compared to other groups treated with airborne particle abrasion or tribochemical silica coating. Clearfil SA Luting showed a significantly higher shear bond strength compared to RelyX ARC and RelyX Unicem. The cohesive failure mode was observed to be dominant in the groups treated with nano-structured alumina coating, while the adhesive failure mode was prevalent in the groups treated with either airborne particle abrasion or tribochemical silica coating.CONCLUSIONNano-structured alumina coating is an effective zirconia surface treatment method for enhancing the bond strength between Y-TZP ceramic and various dual-cured 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.

Effect of Steam Autoclaving on the Tensile Strength of Resin Cements Used for Bonding Two-Piece Zirconia Abutments.

The purpose of this study was to evaluate the effects of steam autoclave sterilization on the tensile strength of two types of resin cements used to bond customized CAD/CAM zirconia abutments onto titanium bases. Forty sets of zirconia abutments cemented to screwed titanium bases of implants analogs were divided into 4 groups (n = 10). Two groups were treated with a conventional chemically activated resin cement (ML, Multilink Ivoclar Vivadent) and the other two groups with a self-adhesive dual resin cement (RelyX U200, 3M ESPE). One group from each cement was submitted to steam autoclaving. The autoclave sterilization cycle was performed after 72 hours of cementation for 15 minutes at 121°C and 2.1 Kgf/cm2. The samples were subjected to tensile strength testing in a universal testing machine (200 Kgf, 0.5 mm/min), from which the means and standard deviations were obtained in Newtons. Results showed (via ANOVA and Tukey's test; α = 0.05) that in the absence of steam autoclaving, no difference was observed in tensile strength between the cements tested: ML: 344.87 (93.79) and U200: 280 (92.42) (P = .314). Steam autoclaving, however, significantly increased tensile strength for the ML: 465.42 (87.87) compared to U200: 289.10 (49.02) (P < .001). Despite the significant increase in the ML samples (P = .013), autoclaving did not affect the tensile strength of the U200 samples (P > 0.05). The authors concluded that steam autoclaving increases the mean tensile strength of the chemically activated cement compared to the dual-cure self-adhesive cement. The performance of both cements evaluated was similar if the sterilization step was disconsidered.

EFFECT OF TIME ELAPSED BETWEEN MIXING AND PHOTOACTIVATION ON DEGREE OF CONVERSION, WATER SORPTION AND WATER SOLUBILITY OF SELF-ADHESIVE RESIN CEMENTS

INTRODUCTION: Self-adhesive resin cements are designed to adhere to tooth structures without separate adhesive or etchant. The major benefit of these materials would appear to be simplicity of applications with the goal of optimizing adhesive cementation procedures, selfadhesive resin cements were developed to simplify the technique and reduce the possibility of failure on the part of the operator. Low degree of conversion (DC), water sorption and solubility can compromise the mechanical properties and longevity of restorations (1-6). OBJECTIVES: Is to determine the influence of the photoactivation protocol on the degree of conversion, sorption and solubility in water of two different types of self-adhesive resin cements. MATERIALS AND METHODS: Two different types of self-adhesive, dual cure resin cements were tested: TEGDMA (Tri-ethylene glycol di-methacrylate) based resin cement [RelyXU200 (RU), 3M ESPE] and UDMA (Urethane di- methacrylate) based resin cement [SmartCem™2 (SC2), Dentsply Caulk]. A total of one hundred and twenty cured disc shaped resin cement specimens were prepared for this study using a split teflon mold to be tested for degree of conversion, water sorption and solubility. The specimens were divided into two groups (n=60) according to the type of the cement used, group A was prepared from RU and group B was prepared from SC2. Each group was divided according to the time elapsed between handling of the resin cement and photo-activation into three subgroups (1, 2 and 3) where n=20. Half of each subgroup specimens (n=10) were used for degree of conversion test while the other half was used for water sorption and solubility test [subgroups A1 & B1 were immediately photo-activated, subgroups A2 & B2 were photo-activated 1 minute after handling the cement and subgroups A3 & B3 were photo-activated 2 minutes after handling the cement]. Ceramic disc (1.5 mm thickness and 10 mm diameter) was fabricated using copper split mold to simulate clinical condition. The specimens were irradiated for 40 seconds using LED light applied perpendicular to the specimens at zero distance between the tip of the light cure unit and the ceramic disc. Fourier transformer infrared spectroscopy (FTIR) was used to determine the degree of conversion. For the water sorption and solubility tests specimens were stored in water bath containing distilled water at 37◦C for 90 days. Data were analyzed using IBM SPSS software package version 20.0 RESULTS: UDMA based cements showed statistically lower degree of conversion for all subgroups compared to TEGDMA based cements which showed significantly higher water sorption than the UDMA based that photo activated after 2 minutes. CONCLUSIONS: The time interval between mixing and photo activation can significantly influence the properties of the cements and modify their behavior

Long-term bond strength of fiber posts cement to dentin with self-adhesive or conventional resin cements

The aim of this study was to evaluate the immediate and the long-term push-out bond strength of glass fiber posts (GFP) cemented with conventional or self-adhesive dual-curing resin cements, at different root depths. Prior to cementation, the GFP (Reforpost #3, Angelus) were etched with 37% phosphoric acid for 30 s followed by silane for 1 min. Thirty canine roots were divided into two groups (n = 15) according to resin cement type: ARC – dual resin cement (RelyX ARC/3M ESPE) combined with an three-step etch-and-rinse adhesive (Adper Scotch Bond Multi-Purpose Plus 3M/ESPE) or U200 – self-adhesive resin cement (RelyX U200/3M ESPE). The manufacturer’s instructions were followed. After 48 h, the roots were cross-sectioned at three different depths, resulting in serial slices corresponding to the cervical, middle, and apical root thirds. Slices were randomly divided into two groups, according to the period of water storage prior to push-out bond strength analysis: 48 h or 180 days. The data (MPa) were analyzed using three-way ANOVA for randomized blocks (p < 0.05), which showed no significant interaction between the three factors (p = 0.716). The main study factors were also proven not significant (cement: p = 0.711; time: 0.288; root third: p = 0.646). In conclusion, root depth, cement type (self-adhesive or conventional), and storage in water for 180 days did not influence the bond strength of GFP to intracanal dentin.

Effect of cyclic loading and resin cement type used for luting fiber posts on bond strength at different root levels of crown-restored human teeth

Objective: This study aimed to evaluate the bond strength (BS) of glass fiber posts (GFP) at different root levels when luted with conventional or self-adhesive cements in crown-restored human premolars subjected, or not, to cyclic mechanical loading.Materials and Methods: Sixty lower premolar roots were endodontically treated and prepared for a GFP system. Half of the roots (n = 30) had their posts cemented with a self-adhesive resin cement, while the remaining roots followed a three-step conditioning method: acid etch, bonding agent, and a conventional resin cement. Metal crowns were luted onto the post-core preparations and the specimens were embedded to simulate the periodontium. Half of the specimens from each group (n = 15) were submitted to cyclic loading simulations (130 N; 2.0 Hz) and then sections were obtained from each root for the pushout BS test.Results: Independently of the cyclic loading and the root level tested, the conventional resin cement provided significantly higher values of BS (p = 0.002). For either cement or either root level, cyclic loading caused a significant decrease in BS values (p = 0.023). The Tukey test indicated that, regardless of the resin cement used or the cyclic loading, BS was highest at the middle and cervical thirds of the root (p = 0.026), and their values did not differ between themselves.Conclusions: When used for luting GFP, self-adhesive resin cement resulted in lower pushout BS than the conventional counterpart, with cyclic loading causing a decrease in BS of the GFP to dentin for both resin cements.

Effects of surface treatments on the shear bond strength of luting cements to zirconia

Objective: The aim of this in vitro study was to evaluate the effect of surface treatments on the shear bond strength of resin cements to zirconia. Material and methods: Sintered zirconia specimens (n = 192) were divided into four different surface treatment groups: control (no treatment); airborne-particle abrasion; glaze layer and hydrofluoric acid (HF) application, and hot etching solution application. Then, each group was divided into four subgroups (n = 12), and three different resin cements were applied to the zirconia surfaces. The shear bond strength value of each specimen was measured after 5000 thermo cycles. The failure types were examined with a stereomicroscope and the effects of the surface treatments were evaluated with a scanning electron microscope. Results were analyzed using analysis of variance and Tukey’s post hoc tests (α = 0.05). Results: The surface treatment and resin cement type significantly affected the bond strength results (p < 0.05). For all resin cements, the airborne-particle abrasion treatment increased the shear bond strength values (p < 0.05). The glaze layer & HF application increased shear bond strength values for all groups, except the Single Bond Universal-RelyX Unicem Aplicap group (p < 0.05). The surface roughness values of airborne-particle abraded specimens were similar to comparable values for specimens from the control group and the hot etching solution group (p > 0.05). The glaze layer & HF application group produced the highest surface roughness values (p < 0.05). Conclusion: The results of this study recommend using the appropriate combination of surface treatment and adhesive/silane coupling agent to achieve durable zirconia-resin bonding.