Fracture resistance and microtensile bond strength of maxillary premolars restored with two resin composite inlay systems

PURPOSE: To compare the in vitro fracture resistance and the microtensile bond strength (muTBS) of premolar teeth restored with two light-cured resin composite inlay systems. METHODS: 50 sound human maxillary premolars were divided randomly into five equal groups. Four groups received mesial-occlusal-distal (MOD) inlay preparations. Restorative treatments comprised: Group 1 (Renew direct resin composite), Group 2 (Renew direct resin composite inlay), Group 3 (Tescera indirect resin composite inlay), Group 4 (non-restored), Group 5 (intact). All teeth were loaded axially until fracture. The same resin-based materials as used in Groups 1-3 were bonded to the superficial coronal dentin of 15 teeth. Beams approximately 1.0 mm x 1.0 mm were prepared and tested in microtensile mode. Results were compared using one-way ANOVA and Tukey's multiple comparison tests. RESULTS: Mean fracture strengths (KN): Group 1, 2.06 (0.76); Group 2, 2.30 (0.49); Group 3, 2.62 (0.68); Group 4, 1.24 (0.44); Group 5, 2.40 (0.71). Group 4 was significantly weaker that the other four groups, P < 0.01. Mean muTBSs (MPa): Group 1, 33.38 (6.24); Group 2, 20.38 (6.24); Group 3, 20.87 (4.62). Group 1 was significantly stronger than the other two groups, P < 0.01.     

Push-out strength and SEM evaluation of resin composite bonded to internal cervical dentin

Abstract The bond strength of a resin composite used with a dual-cured dentin bonding system to internal cervical bovine dentin was evaluated using a direct or indirect placement technique. Teeth were sectioned transversely to produce 4 mm-thick specimens. The root canals were enlarged to a standardized taper, treated with a dentin bonding system, and filled with a lightcured resin composite using either direct, incremental composite placement or indirect composite placement of a pre-polymerized composite inlay. The debond stress of indirectly placed restorations using a composite inlay was 8.5 (SD±2.7) MPa which was significantly greater (p<0.0001) than the value of 5.0 (SD±1.9) MPa for composite placed in a conventional, incremental manner. SEM evaluation revealed the indirect placement technique demonstrated increased resin tag density and length as compared to the direct technique. Enhanced retention of resin composite to endodoutically prepared dentin treated with a dentin bonding system was obtained by using a composite inlay technique as opposed to direct, incremental buildup of the material.     

Effect of resin coating on dentin bond durability of a resin cement over 1 year

PURPOSE: To evaluate the effect of resin coating of bonded dentin on the micro-tensile bond strengths of a resin cement to dentin over 1 year. METHODS: Human molars were ground to obtain flat dentin surfaces and divided into three groups. The dentin surfaces were left as a control, or resin-coated with a combination of a dentin bonding system, Clearfil SE Bond (SE), and one of two lining materials: Protect Liner F (PLF) (SE/PLF) or Ionosit Micro Spand (IMS). The dentin surfaces with or without resin coating were covered with a temporary filling material (Cavit-G) and stored in water for 1 day. After removal of Cavit-G, an indirect composite block (Estenia) was bonded with Panavia F following the manufacturer's instructions. The specimens were stored in water for 1 day, 6 months or 1 year in 37 degrees C water. Micro-tensile bond strength was measured at a crosshead speed of 1 mm/minute. There were 10 slices each group. Data were analyzed with two-way ANOVA and Fisher's PLSD test (P < 0.05). RESULTS: ANOVA indicated that resin coating and storage period significantly influenced the micro-tensile bond strengths (P < 0.0001). The bond strengths of SE/PLF, SE/IMS and the control after 1 day were 27.5 +/- 5.1, 15.7 +/- 3.2 and 10.6 +/- 4.9 MPa, respectively. The bond strengths of SE/PLF significantly decreased over 1 year (P < 0.05), while there were no significant differences in bond strengths for SE/IMS (P > 0.05). The bond strengths of SE/PLF were significantly higher than those of the control over 1 year (P < 0.05).     

Efficacy of water-soluble photoinitiator on the adhesion of composite resin to bovine teeth in all-in-one bonding system

The self-etching primer adhesives examined in the present study were aqueous mixtures of 30 wt% 2-methacryloyloxyethyl phenyl hydrogen phosphate, 35 wt% 2-hydroxyethyl methacrylate, and photoinitiator. For the photoinitiator, camphorquinone (CQ) or 2-hydroxyl-3-(3,4-dimethyl-9-oxo-9H-thioxanthen-2-yloxy)-N,N,N-trimethyl-1-propanaminium chloride (QTX) was used--where QTX is a unique water-soluble photoinitiator. The self-etching primer adhesive was applied directly to polished bovine dentin or enamel. Tensile bond strength of flowable composite resin to bovine teeth was measured after one-day immersion in water at 37 degrees C. The addition of QTX tended to increase tensile bond strength to dentin, whereby addition of 3 wt% of QTX produced the highest mean bond strength of approximately 10 MPa. CQ, on the other hand, did not show any efficacy in improving bond strength. For enamel bonding, there were no significant differences in bond strength between CQ and QTX. In conclusion, QTX was effective in improving the bond strength of composite resin to dentin in an all-in-one bonding system.     

Bond strength of a resin cement to dentin using the resin coating technique

The aim of this study was to evaluate the bond strength of a resin cement to dentin using different adhesive systems (AS) in the presence or absence of a low-viscosity composite liner (Protect Liner F - PLF) applied over the bonded dentin. The adhesive systems selected were: AdheSE/Vivadent (AD); Clearfil Protect Bond/Kuraray (CP); One-Up Bond F/Tokuyama (OU); Single Bond/3M ESPE (SB); Tyrian SPE/One-Step Plus/Bisco (TY); Xeno III/Dentsply (XE) and Unifil Bond/GC (UN). After removing the labial and lingual enamel surfaces of bovine incisors, dentin fragments were prepared and randomly divided into 15 groups (n = 8). The dentin substrates were bonded with the AS and the PLF was applied or not before application of the resin cement (Panavia F, Kuraray). In the control group, the ED Primer (ED) and the resin cement without PLF were used. The AS, PLF and resin cement tested were used according to the manufacturers' instructions, and all treated dentin surfaces were temporized. After water storage for one week, three cylinders of resin cement were applied to each bonded dentin surface, using tygon tubing molds. The specimens were subjected to micro-shear testing and the data were statistically analyzed (two-way ANOVA, Tukey and Dunnett tests, p < 0.05). The observed mean shear bond strengths in MPa were: ED: 20.2 +/- 2.3; AD: 30.3 +/- 6.5; CP: 25.3 +/- 4.4; OU: 28.3 +/- 6.6; SB: 25.6 +/- 6.9; TY: 24.5 +/- 2.5; XE: 17.3 +/- 3.4; UN: 28.4 +/- 6.2; AD+PLF: 32.8 +/- 4.1; CP+PLF: 29.9 +/- 3.9; OU+PLF: 34.1 +/- 4.1; SB+PLF: 29.5 +/- 8.2; TY+PLF: 29.2 +/- 3.9; XE+PLF: 32.8 +/- 6.7; UN+PLF: 32.2 +/- 4.5. The bond strength of the resin cement to dentin using the tested AS was increased when the low-viscosity composite liner was applied.     

Bond strength of dual-cured resin cements to human teeth

PURPOSE: This study evaluated the bond strength of four commercial resin luting cements to enamel and superficial dentin, using a second-generation laboratory composite. MATERIALS AND METHODS: Forty teeth were embedded in acrylic: 20 had superficial dentin exposed; 20 had enamel exposed. Each group was divided into four subgroups (n = 5) to be bonded with Variolink II, Dual Cement, 2-bond-2, and Permalute System, using an inverted, truncated cone of pre-cured Artglass that was placed over the resin cement with a load of 2 N for 2 seconds. Specimens were stored at 37 degrees C in 100% relative humidity for 24 hours before being tested for tensile bond strength (MPa). Data were analyzed using a two-way analysis of variance. Tukey-Kramer intervals for comparisons among resin cements and bonding substrates were calculated at a .05 significance level. RESULTS: Significant differences were found among resin cements. Variolink II had statistically higher bond strength values for both substrates than the rest of the cements evaluated. When bonding was to enamel, all failures were cohesive in the composite, and when bonding was to dentin, some adhesive failures occurred at the resin cement-dentin interface. Permalute System had higher bond strengths than 2-bond-2 and Dual Cement when bonded to enamel. CONCLUSIONS: Variolink II and Permalute had statistically different bond strengths to enamel and dentin. Variolink II showed statistically higher values for dentin bonding than the other cements. Use of Variolink II and Permalute resulted in statistically higher bond strengths than the other two cements.     

Regional measurement of resin-dentin bonding as an array

During the development of the microtensile bond-testing method, large variations in bond strengths were noted among serial sections. The reason for these variations is unknown. The purpose of this work was to determine the consistency of resin-dentin bond strengths across the occlusal surface of coronal dentin by dividing composite resin buildups into an array of 1x1 mm beams, the top half consisting of composite resin, and the bottom half consisting of dentin. Extracted human third molars had the occlusal enamel removed as a single section by means of a diamond saw. Resin composite buildups were made after the dentin was bonded with either One-Step or MacBond. After being stored in 37 degrees C water for 1 day, the teeth were vertically sectioned at 1-mm increments into slabs of bonded teeth. Each slab was further subdivided by vertical sections into 1x1x8 mm beams. Each beam was assigned an x-y coordinate and tested for tensile bond strength. Two different clinicians (A and B) performed the same procedures using One-Step in a parallel study. Using One-Step, clinician A obtained a large number of zero bonds in superficial dentin but fewer in deep dentin. This resulted in a very large standard deviation in bond strengths (mean +/- SD of 22+/-20 MPa in superficial dentin and 27+/-14 MPa in deep dentin). Clinician B obtained much higher (p<0.001) and more uniform bond strengths with One-Step (56+/-13 MPa in superficial dentin and 57+/-12 MPa in deep dentin). With MacBond, there were no zero bonds and hence less variation, with a mean of 41+/-13 MPa in superficial dentin and 27+/-12 MPa (x +/- SD) in deep dentin. When pairs of Z100 resin composite cylinders were bonded together with One-Step and then sectioned into an array, there was little variation in regional bond strength (37 +/-1 MPa). Dividing bonded resin composite buildups into an array of 20 to 30 1x1x8 mm beams allows for the evaluation of uniformity of resin-dentin bonds. The method used in this study detected local regional differences in resin-dentin bond strengths. The largest differences were shown to be related to technique rather than to material. The results indicate that resin-dentin bonds may not be as homogenous as was previously thought.     

三种树脂粘接剂对可切削复合树脂与牙本质粘接强度的比较研究

目的 通过比较3种树脂粘接剂对聚甲基丙烯酸甲酯-纳米二氧化硅-二氧化锆(polymethylmecrylate/nano SiO2-ZrO2,PNSZ)可切削复合树脂与牙本质的粘接强度的差异,寻找适合PNSZ可切削复合树脂的树脂粘接剂,为临床应用提供参考.方法 使用树脂粘接剂A(RelyX ARC)、B(Panavia-F)和c(Variolink II)粘接PNSZ可切削复合树脂与牙本质,测试剪切粘接强度和微拉伸粘接强度(各分为A、B、C 3组,每组10个试件),并采用50倍立体显微镜观察断裂模式.结果 剪切测试中A、B、C组试件的粘接强度分别为(14.07±4.67)、(13.17±4.63)、(12.10±2.18)MPa,差异无统计学意义(P＞0.05);微拉伸测试中A、B、C组试件的粘接强度分别为(11.49±4.90)、(9.66±4.15)、(10.11±4.20)MPa,差异无统计学意义(P＞0.05).立体显微镜观察显示,3种粘接剂的断裂模式均以牙本质-粘接剂界面的断裂为主.结论 3种树脂粘接剂对PNSZ可切削复合树脂与牙本质的粘接效果相近.PNSZ可切削复合树脂一粘接剂界面的粘接优于牙本质-粘接剂界面.     

The effects of luting resin bond to dentin on the strength of dentin supported by indirect resin composite.

OBJECTIVES: The purpose of this study was to evaluate the effects of thickness and adhesion of three resin cements on the fracture resistance of indirect resin composite bonded to dentin. METHODS: A disk of resin composite used for indirect restorations was bonded to a disk of bovine dentin using three kinds of resin cements with various bonding procedures. The bonding procedures were planned into five groups according to the materials and methods, and subsequently subdivided into three groups according to the cement thickness (50, 150 and 500 microm) in each bonding procedure. The thickness of the resin cement and that of the resin composite disk was changed simultaneously while maintaining a total specimen thickness of 2 mm. The prepared specimens were then stored in water at 37 degrees C for 24h at which time they were trimmed to a size of 2 x 2 x 8 mm. The trimmed specimens were subjected to a three point bending test and the fracture load determined. The tensile bond strength of each bonding procedure was measured and the correlation to the fracture load evaluated. RESULTS: The fracture load was affected by the dentin bond strength. The effect of cement film thickness on the fracture load was negligible. SIGNIFICANCE: When an indirect restoration is adhered to the tooth substrate, the adhesion of the luting cement to the tooth substrate is very important for the fracture resistance of indirect resin composite.     

Adhesion of resin composite core materials to dentin

PURPOSE: This study determined (1) the effect of polymerization mode of resin composite core materials and dental adhesives on the bond strength to dentin, and (2) if dental adhesives perform as well to dentin etched with phosphoric acid as to dentin etched with self-etching primer. MATERIALS AND METHODS: Human third molars were sectioned 2 mm from the highest pulp horn and polished. Three core materials (Fluorocore [dual cured], Core Paste [self-cured], and Clearfil Photo Core [light cured]) and two adhesives (Prime & Bond NT Dual Cure and Clearfil SE Bond [light cured]) were bonded to dentin using two dentin etching conditions. After storage, specimens were debonded in microtension and bond strengths were calculated. Scanning electron micrographs of representative bonding interfaces were analyzed. RESULTS: Analysis showed differences among core materials, adhesives, and etching conditions. Among core materials, dual-cured Fluorocore had the highest bond strengths. There were incompatibilities between self-cured Core Paste and Prime & Bond NT in both etched (0 MPa) and nonetched (3.0 MPa) dentin. Among adhesives, in most cases Clearfil SE Bond had higher bond strengths than Prime & Bond NT and bond strengths were higher to self-etched than to phosphoric acid-etched dentin. Scanning electron micrographs did not show a relationship between resin tags and bond strengths. CONCLUSION: There were incompatibilities between a self-cured core material and a dual-cured adhesive. All other combinations of core materials and adhesives produced strong in vitro bond strengths both in the self-etched and phosphoric acid-etched conditions.     

Influence of mechanical properties of two resin cements on durability of bond strength to dentin after cyclic loading

The purpose of this study was to evaluate how the different mechanical properties of two luting agents (acrylic resin cement and resin composite cement) influenced their bond strength to dentin, after cyclic loading that simulated chewing. Stainless steel rods were bonded to the flattened dentin surfaces with each luting agent. After immersion in water for 24 hours, half the specimens of each group were tested for tensile bond strength and the remaining half were subjected to a vertical load (75.6 N, 1.2 Hz) using an acrylic stylus--which upon contact with the specimen would rotate counterclockwise and then counter-rotate. Bond strength of the resin composite cement with self-etching was found to be significantly lower than the other adhesive systems. After 100,000 cycles, the bond strength of resin composite cement was significantly decreased while acrylic resin cement showed no decrease in bond strength.     

Influence of endodontic materials on the bonding of composite resin to dentin.

We assessed the bond strength of a composite resin to dentin that had been in contact with different materials. Flat dentin surfaces in freshly extracted human teeth were covered for 15 min or 48 h with a 1-mm layer of a variety of materials. The products were mechanically removed and a composite resin cylindrical specimen bonded to the dentin surface using the Prisma universal bond system. After 7 days immersion at 37 degrees C in water, the tensile bond strength was tested. The results were compared with those on dentin surfaces not in contact with any endodontic material. Statistical analysis showed that some materials (Grossmans Cement, IRM, Maisto's slowly resorbable paste) reduced the strength of the bond or even precluded bonding. It is necessary to develop techniques that will eliminate this when restoring endodontically treated teeth.     

In vitro shear bond strength of resin-based luting cements to dentin

The aim of this study was to determine how resin cement, self-adhesive resin cement, and resin-modified glass ionomer cement affected shear bond strength to dentin. Sixty composite resin disks (3 mm in diameter x 3 mm in length) were prepared and divided into four groups (n = 15): Group 1, composite disk bonded to dentin with composite resin and a bonding agent; Group 2, composite disk bonded to dentin with a self-adhesive resin cement; Group 3, composite disk bonded to dentin with a different self-adhesive resin cement; and Group 4, composite disk bonded to dentin with a resin-modified glass ionomer cement. The composite resin was loaded into a syringe (internal diameter 3 mm), photocured in an oven, and cut into 3 mm slices with a low-speed saw. The samples were bonded to dentin per the manufacturer's instructions. All specimens were stored in distilled water (at 37 degrees C) for 24 hours. The shear bond strength test was conducted using a universal testing machine at a crosshead speed of 0.5 mm/min until failure. Conventional resin cement and a bonding agent exhibited significantly higher shear bond strength values than all other materials tested.     

Enhancement of adhesion between resin coating materials and resin cements

Resin coating technique is a unique method that improves the dentin bond strength of resin cements in indirect restorations. However, the weak link of a specimen bonded using the resin coating technique was reported to be the bonded interface between the resin coating material and resin cement. The purpose of this study, therefore, was to enhance the bonding performance between a resin coating material and a resin cement. Two light-cured flowable composites, Protect Liner F and Clearfil Flow FX, were used as coating materials, and two dual-cure composite materials, Panavia F 2.0 and Clearfil DC Core Automix, were used as resin cements. The ultimate tensile strength of each material and the microtensile bond strengths of the bonded specimens of resin coating material and resin cement were measured using a crosshead speed of 1.0 mm/min. Three-way ANOVA (p=0.05) revealed that the highest microtensile bond strength was obtained using a combination of Clearfil Flow FX and Clearfil DC Core Automix, and when the surface of the coating material was treated with ED Primer II. It was strongly suggested that materials with a higher ultimate tensile strength, when used in both resin coating and cementation, could enhance the bond strength between the two.     

Influence of endodontic materials on the bonding of composite resin to dentin

Abstract We assessed the bond strength of a composite resin to dentin that had been in contact with different materials. Flat dentin surfaces in freshly extracted human teeth were covered for 15 min or 48 h with a 1-mm layer of a variety of materials. The products were mechanically removed and a composite resin cylindrical specimen bonded to the dentin surface using the Prisma universal bond system. After 7 days immersion at 37°C in water, the tensile bond strength was tested. The results were compared with those on dentin surfaces not in contact with any endodontic material. Statistical analysis showed that some materials (Grossmans Cement, IRM, Maisto's slowly resorbable paste) reduced the strength of the bond or even precluded bonding. It is necessary to develop techniques that will eliminate this when restoring endodontically treated teeth.     

两种不同固化处理的复合树脂黏接微拉伸强度测试研究

目的　对不同固化处理的复合树脂黏接微拉伸强度进行测试。方法　新鲜拔除的完好无龋、人下颌第三磨牙15颗,随机分成3组,用Isomet低速切割机流水冲洗下磨去咬合面釉质,暴露牙本质,用Renew树脂直接充填、Renew树脂间接修复、Tescera树脂间接修复制作树脂“冠”并黏接在牙本质面上,贮存于室温水中2 4h ,测试微拉伸强度。结果　Renew树脂直接充填组(33.38±6 .2 4 )MPa的微拉伸强度高于Renew间接修复组(2 0 .0 6±4 .96 )MPa和Tescera间接修复组(2 0 .87±4 .6 2 )MPa ,差异有显著性(P <0 .0 5 ) ,后两者之间差异无显著性。结论　树脂直接充填的微拉伸强度要高于树脂间接修复。     

Influence of water flow rate on shear bond strength of resin composite to Er:YAG cavity preparation

PURPOSE: To evaluate in vitro the influence of water flow rate on shear bond strength of a resin composite to enamel and dentin after Er:YAG cavity preparation. METHODS: Ten bovine incisors were selected and roots removed. Crowns were sectioned in four pieces, resulting in 40 samples that were individually embedded in polyester resin (n = 10), and ground to plane the enamel and expose the dentin. The bonding site was delimited and samples were randomly assigned according to cavity preparation: (1) Er:YAG/1.0 mL/minute; (2) Er:YAG/1.5 mL/minute; (3) Er:YAG/2.0 mL/minute and (4) High speed handpiece/bur (control group). Samples were fixed to a metallic device, where composite resin cylinders were prepared. Subsequently, they were stored for 24 hours and subjected to a shear bond strength test (500N at 0.5 mm/minute). RESULTS: Means (MPa) were: enamel: 1: 12.8; 2: 16.8; 3: 17.5; 4: 36.0 and Dentin: 1: 13.6; 2: 18.7; 3: 12.1; 4: 21.3. Data were submitted to ANOVA and Tukey's test. Adhesion to enamel was more efficient than for dentin. The cavities prepared with conventional bur (control) presented higher statistically significant bond strength values (P < 0.05) than for Er:YAG laser for both enamel and dentin. No significant differences were observed between water flow rates employed during enamel ablation. For dentin, the shear bond strength of 2.0 mL/minute water flow rate was lower than for 1.5 mL/minute and 1.0 mL/minute rates. The Er:YAG laser adversely affected shear bond strength of resin composite to both enamel and dentin, regardless of the water flow rate used.     

The bond of resin to different dentin surface characteristics

This study investigated the effects of dentin surface characteristics on bond strengths between resin and dentin. The shear bond strengths mediated by two dentin adhesive systems (Clearfil SE Bond and OptiBond Solo Plus) were evaluated. For each material, flat dentin surfaces prepared from human upper premolars were allocated to eight groups according to three characterizations; dentin location (occlusal or cervical), dentin depth (superficial or deep) and dentinal tubule orientation (perpendicular or parallel). A 0.75-mm diameter area of dentin was bonded according to each manufacturer's instructions before placing 0.5-mm high resin composite. The bonds were stressed in shear at a crosshead speed of 1 mm/minute. The mean bond strengths were compared using ANOVA and independent t-test. No statistically significant differences were found in shear bond strengths based on dentin location. Clearfil SE Bond presented higher bond strengths to deep dentin specimens bonded perpendicular to the tubules compared to those that were bonded parallel to the tubules. Whereas, the opposite results were found for deep dentin specimens bonded with OptiBond Solo Plus. In the case of superficial dentin, there were no differences between the two materials when bond strengths were compared among the different orientations of tubule. The results indicated that shear bond strengths may be affected by dentin depth, orientation of the tubule and the bonding material used, but not by location of the dentin.     

Tensile bond strength of four resin luting agents bonded to bovine enamel and dentin

STATEMENT OF PROBLEM: The resistance to fracture of ceramic restorations depends on adequate bonding to tooth structure. The dental substrate and the types of resin luting agents used are believed to produce variability in adhesive properties. PURPOSE: The purpose of this study was to evaluate the tensile bond strength of 4 resin luting agents to bovine enamel and dentin. MATERIAL AND METHODS: Forty bovine incisors were embedded in acrylic resin and ground horizontally with water-cooled silicon carbide paper to expose enamel (20 teeth) and dentin at the enamel/dentin junction (20 teeth). Ten standard cone-shaped specimens with a 3-mm diameter base were prepared for each of the following resin cements: Resin Cement, Rely X ARC, Nexus, and Enforce. Five specimens of each material were bonded to enamel and the other 5 to dentin with these resin luting agents and their respective adhesive systems, according to the manufacturers' directions. After 7 days of storage in distilled water at 37 degrees C, specimens were subjected to tensile forces in a universal testing machine at a crosshead speed of 0.5 mm/min until fracture. Bond strength data were analyzed with analysis of variance for substrate and material. Means were compared with Tukey's test at the 0.05 level of significance. RESULTS: Analysis of variance disclosed that both substrate (P<.001) and material (P<.05) demonstrated statistically significant differences, but their interaction was not significant. The bond strengths (MPa) obtained for Resin Cement (11.5 +/- 3.0), Rely X ARC (11.4 +/- 3.1), Nexus (10.0 +/- 1.4), and Enforce (11.8 +/- 2.8) were statistically the same for enamel. For dentin, bond strengths (MPa) for Rely X ARC (9.6 +/- 1.8), Resin Cement (9.3 +/- 0.9), and Enforce (7.8 +/- 2.9) were significantly higher than for Nexus (3.5 +/- 0.8). Significantly higher bond strengths (MPa) were also observed for enamel (11.2 +/- 2.5) than dentin (7.5 +/- 1.6). CONCLUSION: Within the limitations of this study, tensile bond strengths of resin luting agents to enamel were higher than those to dentin, and the bond strength values of Nexus to dentin were significantly lower (P<.05) than the other cements tested.     

Shear bond strength of resin cements to both ceramic and dentin

STATEMENT OF PROBLEM: All ceramic restorations benefit from resin cement bonding to the tooth. However, the literature is unclear on which cement, ceramic conditioning treatment, and dentin bonding agent produce the highest and longest-lasting bond strength. PURPOSE: This in vitro study evaluated immediate and 6-month shear bond strengths between a feldspathic ceramic and 4 different resin cements with the use of 6 different surface-conditioning treatments. Shear bond strengths between the 4 resin cements and dentin also were measured. MATERIAL AND METHODS: Four hundred eighty discs (10 mm in diameter and 4 mm thick) of Ceramco II porcelain were randomly divided into 6 main groups (n = 80). The ceramic specimens received 6 different surface conditioning treatments before the application of resin cement. These surface treatments were sanding with 600-grit silicon carbide paper, microetching with aluminum oxide, sanding followed by silane application, microetching followed by silane application, hydrofluoric acid-etching, and hydrofluoric acid-etching followed by silane application. Each group then was subdivided into 4 subgroups (n = 20) for the application of 1 of 4 cements: Nexus, Panavia 21, RelyX ARC, and Calibra. All cemented specimens were tested under shear loading until fracture on a universal testing machine; the load at fracture was reported in MPa as the bond strength. Bond strengths were determined at 24 hours and after 6 months of specimen storage in a saline solution. For dentin-resin cement shear bond strength testing, dentin specimens were treated with dentin bonding agents, and a thin layer of resin cement was applied according to the manufacturer's directions. Prodigy composite was bonded to the cement. Shear bond strengths were determined as above and reported in MPa at fracture. Data were analyzed with 3-way analysis of variance (P<.01). RESULTS: Hydrofluoric acid-etching followed by silane application produced bond strengths (15.0 +/- 7.4 to 21.8 +/- 5.8 MPa) in the highest statistical group with all 4 cements at both 24 hours and 6 months (P<.01). Sanding with 600-grit silicon carbide paper and microetching with aluminum oxide produced the lowest bond strengths (0.0 to 4.0 +/- 3.5 MPa). At 24 hours and 6 months, there were no significant differences among the 4 cements when hydrofluoric acid-etching was followed by silane application. Both auto- and light-polymerized dentin bonding agents bonded better to dentin than dual-polymerized bonding agents. CONCLUSION: Within the limitations of this study, hydrofluoric acid-etching followed by silane application produced the best bonds at 24 hours and 6 months with all 4 cements. Auto- and light-polymerized adhesives were associated with higher bond strengths to dentin than dual-polymerized adhesives.