Comparison of bond strengths of denture base resins to nickel-chromium-beryllium removable partial denture alloy

Purpose. In vitro bond strengths of a traditional denture base resin (Lucitone 199) and three adhesive denture base resins (Meta-Dent, Meta-Fast with liner, and Meta-Fast without liner) to treated nickel-chromium-beryllium (Ni-Cr-Be) partial denture alloy were tested with four alloy surface pretreatments (sandblast, Met-etch, Rocatec with silane, and Rocatec without silane), with or without primer (Dentsply). The Lucitone 199 resin bonded to the nonprimed sandblasted group was the control group. The hypothesis was the use of alloy pretreatments and/or primer does not improve the bond strength of denture base resins to sandblasted Ni-Cr-Be partial denture alloy.Material and methods. Primed and nonprimed bonded specimens were prepared and finished, stored in 37° C distilled water for 24 hours, then debonded in tension on a testing machine. The bond strength was calculated in megapascals (MPa). Five specimens were prepared and tested for each experimental condition, both with and without primer, for a total of 160 specimens.Results. For three-way analysis of variance, the main effects of resins and treatment were statistically significant (p < 0.05), but the main effect of primer was not statistically significantly (p > 0.05). Without primer, the control group had the lowest bond strength (0 MPa). The three adhesive resin groups produced significantly higher bond strengths than the Lucitone resin groups. For the treated groups, nearly all sandblasted groups produced significantly lower bond strength than the other three treated groups. Meta-Dent to Met-etch treated group had the highest bond strength (23.9 MPa). With primer, the bond strengths of the Lucitone resin groups were significantly higher than the nonprimed groups, and the Lucitone resin-primed Rocatec treated group had the highest bond strength (14.8 MPa). For the three adhesive denture base resins, nearly all primed treated groups had significantly lower bond strengths than nonprimed groups.Conclusions. Without primer, the Lucitone resin-sandblast treated group (control) had the lowest bond strength (0 MPa). The Meta-Dent denture base resin with the Met-etch treated group had the highest bond strength (23.9 MPa). With primer, the Lucitone resin-primed Rocatec-silane treated group had the highest bond strength (14.8 MPa). For the adhesive denture base resins, nearly all bond strengths of the primed treated groups were significantly lower than the values of the nonprimed groups. (J Prosthet Dent 1997;78:566-73.)     

不同金属处理剂对钴铬合金与基托树脂粘结强度的影响

目的:研究三种金属处理剂对钴铬合金与基托树脂粘接强度的影响。方法:制备40个钴铬合金试件随机分为4组,采用喷砂和激光对各个试件表面进行处理后,除对照组外,其它组试件分别采用Metal Primer II,Estenia Opaque Primer,Metal Base M三种金属处理剂对试件表面进行处理,后将基托树脂与金属试件进行粘接。经37℃恒温水浴24h后,测定金属试件与基托树脂间的剪切粘接强度,并进行统计分析。结果:三种金属处理剂组所获得的钴铬合金与基托树脂间的剪切粘接强度均显著高于对照组(P<0.05)。Metal Primer II组与Estenia Opaque Primer组所获得的钴铬合金与基托树脂间的剪切粘接强度显著高于Metal Base M组(P<0.05),Metal Primer II组与Estenia Opaque Primer组间差异无统计学意义(P>0.05)。结论:三种金属处理剂均能提高钴铬合金与基托树脂间的剪切粘接强度,Metal Primer II和Estenia OpaquePrimer提高钴铬合金与基托树脂间剪切强度的效果优于Metal BaseM。     

3种树脂粘接水门汀与铸造纯钛粘接强度研究

目的：研究3种复合树脂粘固剂与铸造纯钛的粘接强度。方法：用牙科铸钛的方法制作直径分别为4mm和5mm的钛棒,切割成长度为4mm的小钛片。2种规格的钛片配对粘接面用400～1200目碳化硅砂纸在流水下打磨抛光,使之呈均匀一致的平面。50μm氧化铝喷砂,另一组表面不喷砂作为对照,分别使用Super-BondC＆B、Panavia F、Rely X Unicem 3种复合树脂粘固剂粘接。扫描电镜观察喷砂前后铸造纯钛的表面形态。复合树脂粘接剂固化后经37℃恒温水浴24h以及5000次5～55℃冷热循环,测试剪切强度。用SAS的ANOVA过程对各组数据进行分析。结果：喷砂前后纯钛与Panavia F的剪切强度最高,分别为（26.62±3.40）MPa、（23.71±5.28）MPa;5000次冷热循环后,喷砂组的铸造纯钛与Panavia F的剪切强度最高（27.12±8.68）MPa;未喷砂的铸造纯钛与Super-Bond C＆B、Rely X Unicem的粘接强度最低,并且有12.5%的脱落率。结论：本实验结果表明喷砂可以提高Super-Bond C＆B、Panavia F、Rely X Unicem的粘结力和粘结耐久力。不喷砂时,Panavia F与铸造纯钛之间能获得较高的粘接强度和良好的粘接耐久性,喷砂以后优势不再明显。     

Use of metal conditioners to improve bond strengths of autopolymerizing denture base resin to cast Ti-6Al-7Nb and Co-Cr

OBJECTIVE: The shear bond strengths of an autopolymerizing denture base resin to cast Ti-6Al-7Nb and Co-Cr alloys using three metal conditioners were investigated. METHODS: Ti-6Al-7Nb alloy and Co-Cr alloy discs were cast. The disc surfaces were air-abraded with 50 microm alumina particles and treated with three metal conditioners (Alloy Primer; Cesead II Opaque Primer; Metal Primer II). An autopolymerizing denture base resin was applied on the discs within a hole punched in a piece of sticky tape and a Teflon ring to define the bonding area. All specimens were immersed in 37 degrees C water for 24 h. Half of the specimens were thermocycled up to 20,000 cycles. The shear bond strengths were determined at a crosshead speed of 1.0 mm/min. RESULTS: Specimens treated with the three metal conditioners had significantly (p<0.05) improved shear bond strengths of the autopolymerizing denture base resin to both Ti-6Al-7Nb and Co-Cr. Although the bond strengths of the bonded Ti-6Al-7Nb specimens were higher than those of the Co-Cr alloy before thermocycling, the decrease in the bond strength of Ti-6Al-7Nb was considerably greater than that of the Co-Cr after thermocycling. CONCLUSION: Significant improvements in bond strength of the autopolymerizing denture base resin to cast Ti-6Al-7Nb alloy and Co-Cr alloy were achieved through the application of Alloy Primer, Cesead II Opaque Primer and Metal Primer II. The bond durability to Ti-6Al-7Nb alloy was inferior to that to Co-Cr.     

Shear bond strengths of polymethyl methacrylate to cast titanium and cobalt-chromium frameworks using five metal primers

STATEMENT OF PROBLEM: Poor chemical bonding of a denture base resin to cast titanium frameworks often introduces adhesive failure and increases microleakage. PURPOSE: This study examined the shear bond strengths of a denture base resin to cast pure titanium, Ti-6Al-4V, and a cobalt-chromium alloy using various adhesive primers. MATERIAL AND METHODS: Disks (6.0 mm diameter, 2.5 mm thick) were cast of the 3 alloys. The disk surfaces were grit-blasted with 50 microm alumina and treated with 5 different metal primers (Metal Primer II ?MP]; Cesead Opaque primer ?OP]; Meta Base ?MB]; experimental primer ?EP]; Siloc bonding system ?SI]). A denture base resin (Palapress Vario) was then applied on the disks with hole-punched sticky tape (bonding area of 5.0 mm) and a Teflon (PTFE, New Age Industries Inc, Willow Grove, Pa.) ring (6.0 mm diameter x 2.0 mm thick). Specimens without primer were also prepared as controls. All specimens were immersed in 37 degrees C water and thermocycled up to 2,000 cycles. Shear bond strength values were determined at a crosshead speed of 0.5 mm/min. Data were statistically analyzed using 3-way ANOVA, followed by 1-way ANOVA and the Scheffé multiple range test. RESULTS: Primers significantly (P <.05) improved shear bond strengths of denture base resin to all metals, among which no significant differences were found. Specimens primed with OP, MP, and EP showed higher bond strengths than did those primed with MB. After thermocycling, the bond strengths of MB and SI decreased substantially; MB showed the least durability (22.8% to 35.5% decrease) among the primers. CONCLUSION: The application of 5 primers significantly improved the shear bond strengths of a denture base resin to cast CP titanium, Ti-6Al-4V, and Co-Cr alloy. OP and MP primers exhibited greater bond strength and durability than did MB and SI.     

Evaluation of the Bond Strength of Denture Base Resins to Acrylic Resin Teeth: Effect of Thermocycling

Purpose: The purpose of this study was to evaluate the thermocycling effects and shear bond strength of acrylic resin teeth to denture base resins.
Materials and Methods: Three acrylic teeth (Biotone, Trilux, Ivoclar) were chosen for bonding to four denture base resins: microwave-polymerized (Acron MC), heat-polymerized (Lucitone 550 and QC-20), and light-polymerized (Versyo.bond). Twenty specimens were produced for each denture base/acrylic tooth combination and were divided into two groups (n = 10): without thermocycling (control groups) and thermocycled groups submitted to 5000 cycles between 4 and 60°C. Shear strength tests (MPa) were performed with a universal testing machine at a crosshead speed of 1 mm/min. Statistical analysis of the results was carried out with three-way ANOVA and Bonferroni's multiple comparisons post hoc analysis for test groups (α= 0.05).
Results: The shear bond strengths of Lucitone/Biotone, Lucitone/Trilux, and Versyo/Ivoclar specimens were significantly decreased by thermocycling, compared with the corresponding control groups ( p < 0.05). The means of Acron/Ivoclar and Lucitone/Ivoclar specimens increased after thermocycling ( p < 0.05). The highest mean shear bond strength value was observed with Lucitone/Biotone in the control group (14.54 MPa) and the lowest with QC-20/Trilux in the thermocycled group (3.69 MPa).
Conclusion: Some acrylic tooth/denture base resin combinations can be more affected by thermocycling; effects vary based upon the materials used.     

Effect of sandblasting on the bond strength of the bondable molar tube bracket

This study examined the effect of surface treatment with sandblasting on bracket bonding strength. Extracted human tooth, base metal alloy and porcelain surfaces were treated with sandblasting. The bracket bonding strengths of sandblasted surfaces were evaluated and compared with the controls and etched enamel surfaces. Morphological observation of the treatment surfaces and the failure sites was conducted. Statistical analysis included one-way analysis of variance (ANOVA) and a Scheffe's F-test at the 95% confidence level was performed. The results indicated that mean bond strength values ranged from 3.6 MPa (the untreated control) to 20.4 MPa for the etched enamel surface. No statistically significant differences were determined among the etched enamel, sandblasted metal and sandblasted porcelain surfaces (P > 0.05). Most debonding specimens failed at either the resin-tooth interface or within the adhesive. In conclusion, sandblasting the metal and porcelain surfaces obtained a bracket bond strength comparable with that with the etched enamel surface.     

Effect of laboratory procedures and thermocycling on the shear bond strength of resin-metal bonding systems

STATEMENT OF PROBLEM: During fabrication or repair of removable partial dentures, resin-to-metal or resin-to-denture tooth bonds may be stressed by laboratory procedures. PURPOSE: The purpose of this in vitro study was to evaluate the effect of steam cleaning, boiling, ultrasonic cleaning (laboratory procedures), and thermocycling on shear bond strength of resin bonds to metal and denture teeth. MATERIAL AND METHODS: Resin-metal bonding systems and their specific veneer resins (Rocatec, Sinfony; Rocatec, Visio-Gem, HLC-BOND, Zeta LC and Ducera experimental veneer resin) were tested on a Co-Cr alloy (Wirobond C). The veneer resins were bonded to resin denture teeth. The experimental groups (n=7) were subjected to the following conditions: 24-hour storage of the specimens in air (group I, control group), storage in air and treated with simulated laboratory procedures (2 minutes steam cleaning, 15 minutes ultrasonic cleaning at room temperature, 1 hour boiling in water, group II), storage in air with thermocycling (5000 cycles, 5 degrees to 55 degrees C, group III), storage in air with laboratory procedures followed by thermocycling (group IV), and storage in air with thermocycling followed by laboratory procedures (group V). Shear strength tests (MPa) were performed with a universal testing machine until fracture. After shear bond testing, the failure mode of the resin-metal and resin-denture tooth bonds was assessed. Statistical analysis of the results was carried out with one-way analysis of variance and Bonferroni-Dunn's multiple comparisons post hoc analysis for test groups (alpha=0.05). RESULTS: Except for Ducera/denture tooth specimens (groups III to V: 8.7 +/- 3.4-9.1 +/- 1.7; 10.8 +/- 1.9 MPa control group), the Wirobond C and denture tooth specimens (groups III, IV and V: 1.4 +/- 0.9-11.9 +/- 2.3 MPa), showed significantly lower shear bond strengths than the corresponding control groups (7.5 +/- 2.9-21.0 +/- 3.4 MPa, P<.05). The shear bond strengths of group II of Sinfony/Wirobond C (11.6 +/- 3.3 MPa, P<.0001), Visio-Gem/Wirobond C (7.4 +/- 1.9 MPa, P<0.0001), Ducera/Wirobond C (11.8 +/- 2.9 MPa, P<.0001) and of Zeta/denture tooth (3.9 +/- 1.6 MPa, P=.0005) were significantly decreased by steam, boiling, and ultrasonic procedures compared with the corresponding control groups (21.0 +/- 3.4 MPa; 14.7 +/- 4.0 MPa; 19.1 +/- 2.3 MPa; 7.5 +/- 2.9 MPa, respectively). No significant differences were noted among groups III, IV, and V. Co-Cr specimens subjected to the Rocatec system and bonded with Sinfony and HLC BOND/Zeta specimens showed cohesive failure. Adhesive failure was observed for the experimental veneer resin on the Co-Cr specimens and for all veneer resins on the denture teeth. CONCLUSION: Simulation of laboratory procedures and thermocycling caused a significant drop in shear bond strength of metal-resin and denture tooth-resin bonds for most of the tested veneer resins. Thermocycling before shear testing had the same effect on veneer resin bond strength as the simulated laboratory procedures.     

Factors affecting the bond strength of denture base and reline acrylic resins to base metal materials

Objective

The shear bond strengths of two hard chairside reline resin materials and an auto-polymerizing denture base resin material to cast Ti and a Co-Cr alloy treated using four conditioning methods were investigated.

Material and Methods

Disk specimens (diameter 10 mm and thickness 2.5 mm) were cast from pure Ti and Co-Cr alloy. The specimens were wet-ground to a final surface finish of 600 grit, air-dried, and treated with the following bonding systems: 1) air-abraded with 50-70-µm grain alumina (CON); 2) 1) + conditioned with a primer, including an acidic phosphonoacetate monomer (MHPA); 3) 1) + conditioned with a primer including a diphosphate monomer (MDP); 4) treated with a tribochemical system. Three resin materials were applied to each metal specimen. Shear bond strengths were determined before and after 10,000 thermocycles.

Results

The strengths decreased after thermocycling for all combinations. Among the resin materials assessed, the denture base material showed significantly (p<0.05) greater shear bond strengths than the two reline materials, except for the CON condition. After 10,000 thermocycles, the bond strengths of two reline materials decreased to less than 10 MPa for both metals. The bond strengths of the denture base material with MDP were sufficient: 34.56 MPa for cast Ti and 38.30 for Co-Cr alloy.

Conclusion

Bonding of reline resin materials to metals assessed was clinically insufficient, regardless of metal type, surface treatment, and resin composition. For the relining of metal denture frameworks, a denture base material should be used.     

喷砂对不同树脂与纯钛粘结抗剪强度及粘结耐久力的影响

目的探讨喷砂处理对不同树脂与纯钛粘结抗剪强度及粘结耐久力的影响。方法用牙科铸钛的方法制作φ5 mm×5 mm及φ4 mm×2 mm的圆柱形钛段各96个,两种规格的钛段配对(共96对)。分成实验组和对照组。实验组钛粘接表面用50μm Al2O3喷砂,对照组钛表面不做处理。分别用Super-Bond C&B(SB)、Panavia F(PF)和Rely X Unicem(RU)按生产厂商提供的要求将大、小钛段成对粘接。分为SB未喷砂、SB喷砂、PF未喷砂、PF喷砂、RU未喷砂、RU喷砂6组(每组16对)。将以上每组中的一半样品(每组8对)置于37℃水浴箱内24 h,,另一半样品水储24 h后再进行5 000次冷热循环。将样品固定于MTS测试机上进行剪切强度的测试,计算粘结抗剪强度值。不同粘结剂组的粘结抗剪强度采用考虑交互作用的两因素方差分析进行统计学分析。结果冷热循环前,RU未喷砂组的粘接抗剪强度最低,SB喷砂组粘接抗剪强度最高,为(28.03±8.40)MPa,5 000次冷热循环后,PF喷砂组粘接抗剪强度最高,为(27.12±8.68)MPa,RU未喷砂组最低。冷热循环前,SB喷砂组和SB未喷砂组,RU喷砂组和RU未喷砂组的粘接抗剪强度值差异有统计学意义(P<0.05)。5 000次冷热循环后,RU喷砂组和RU未喷砂组的粘接抗剪强度值差异有统计学意义(P<0.05)。SB未喷砂组、SB喷砂组5 000次冷热循环前、后的粘接抗剪强度值差异有统计学意义(P<0.05)。其余各组5 000次冷热循环前、后的粘接抗剪强度值差异没有统计学意义(P>0.05)。结论喷砂能显著提高铸造纯钛与SB、RU的粘接抗剪强度及粘结耐久力,但不是和所有树脂与纯钛的粘接抗剪强度及粘结耐久力成正相关关系。     

Effect of surface preparation on the bond strength of heat-polymerized denture base resin to commercially pure titanium and cobalt-chromium alloy

The aim of this study was to investigate the bond durability of heat-polymerized denture base resin to cast CP Ti and Co-Cr alloy. The alloy specimens were divided into five groups: 1) airborne-particle abraded with 50 μm alumina (SAND), 2) Rocatec tribochemical silica coating system (RO), 3) air-abraded followed by application of Epricord Opaque Primer (EP), 4) air-abraded followed by application of Super Bond C&B liquid (SB), 5) air-abraded followed by application of Alloy Primer (AL). Heat-polymerized denture resin was applied to the bonding area and polymerized according to the manufacturer's instructions. The halves of all specimens were thermocycled up to 10,000 cycles. Before thermocycling SB and AL showed significantly higher shear bond strengths than SAND, RO, EP for both metals. The shear bond strength of AL group after thermocycling was significantly higher than that of the other groups.     

不同表面处理对义齿软衬树脂黏结强度的影响

目的:探讨4种不同表面处理对义齿软衬树脂与硬质树脂之间黏结强度影响。方法:制作热凝硬质基托树脂试件(直径8mm,长度15mm)和热凝义齿软衬树脂试件(厚4mm,直径10mm),然后将2个硬质树脂试件黏结在软衬树脂正反两面的中心。采用4种不同表面处理方式——第1组,对照组,不加任何处理;第2组,喷砂粗化处理;第3组,专用黏结剂涂布表层;第4组,表层涂布 喷砂粗化。每组各10个试件,分别测定黏结强度,采用SPSS10.0软件进行单因素方差分析。结果:第1、2、3、4组的平均黏结强度分别为3.518、2.834、4.077和3.852MPa。F=6.40,P<0.0014。表层涂布组的黏结强度最高,而喷砂组的黏结强度最低。结论:使用专用黏结剂表层涂布,可显著增强义齿软衬树脂的黏结强度;而进行喷砂处理,反而会使黏结强度下降。     

EFFECT OF THERMOCYCLING ON THE TENSILE AND SHEAR BOND STRENGTHS OF THREE SOFT LINERS TO A DENTURE BASE RESIN

Statement of problem

In clinical practice, loss of adhesion between the silicone-based denture liner and the denture base resin is always an undesirable event that might cause loss of material softness, water sorption, bacterial colonization and functional failure of the prosthesis.

Purpose

This study evaluated the effect of thermocycling on tensile and shear bond strengths of three soft liner materials to a denture base acrylic resin.

Material and methods

Three resilient liners (Mucopren-Soft, Mollosil-Plus and Dentusil) and a heat-polymerized acrylic resin (QC-20) were processed according to manufacturers’ directions. Sixty specimens (14 x 14 mm cross-sectional area) per bond strength test (20 for each liner) were fabricated and either stored in water at 37°C for 24 hours (control groups; n=10) or thermocycled 3,000 times in water between 5°C and 55°C (test groups; n=10). The specimens were tested in tensile and shear strength in a universal testing machine until fracture. Bond strength means were compared between water-stored and thermocycled groups for each material, as well as among materials for each treatment (water storage or thermocycling). Failure mode (adhesive, cohesive and mixed) after debonding was assessed. Data were analyzed statistically by paired Student’s t-test and ANOVA at 5% significance level.

Results

The water-stored groups had statistically significant higher bond strengths than the thermocycled groups (p<0.05). Without thermocycling, Mucopren-Soft (2.83 ± 0.48 MPa) had higher bond strength than Mollosil-Plus (1.04 ± 0.26 MPa) and Dentusil (1.14 ± 0.51 MPa). After thermocycling, Mucopren-Soft (1.63 ± 0.48 MPa) had the highest bond strength (p<0.05).

Conclusion

The bond strength of the three soft denture liners tested in this study changed with their chemical composition and all of them exhibited higher bond strengths than those usually reported as clinically acceptable.

Clinical Implications

All soft lining materials tested in this study showed a significant decrease in the bond strength to an acrylic denture base resin after thermocycling. In spite of thermocycling, though, the silicone-based liners had satisfactory bond strengths for clinical application.     

Evaluation of thiouracil-based adhesive systems for bonding cast silver-palladium-copper-gold alloy

This study aimed to evaluate the effect of adhesive systems based on a thiouracil monomer on bonding to silver-palladium-copper-gold (Ag-Pd-Cu-Au) alloy (Castwell M.C.12). Disk specimens were cast from the alloy and then air-abraded with alumina. The disks were bonded using six bonding systems selected from four primers and three luting materials. Shear bond strengths were determined both before and after thermocycling. Bond strength varied from 2.7 MPa to 32.0 MPa. Three systems based on a thiouracil monomer (MTU-6) showed durable bonding to the alloy, with post-thermocycling bond strengths of 22.4 MPa for the Metaltite (MTU-6) primer and Super-Bond, a tri-n-butylborane (TBB) initiated resin, 9.0 MPa for the Multi-Bond II resin, and 8.1 MPa for the Metaltite and Bistite II system. It can be concluded that a combination of thiouracil-based primer and TBB initiated resin is effective for bonding Ag-Pd-Cu-Au alloy.     

In Vitro Tensile Bond Strength of Denture Repair Acrylic Resins to Primed Base Metal Alloys Using Two Different Processing Techniques

Purpose: Approximately 38% of removable partial denture (RPD) failures involve fracture at the alloy/acrylic interface. Autopolymerizing resin is commonly used to repair RPDs. Poor chemical bonding of repair acrylic to base metal alloys can lead to microleakage and failure of the bond. Therefore, ideal repair techniques should provide a strong, adhesive bond. This investigation compared the tensile bond strength between cobalt‐chromium (Super Cast, Pentron Laboratory Technologies, Llc., Wallingford, CT) and nickel‐chromium (Rexalloy, Pentron Laboratory Technologies, Llc.) alloys and autopolymerized acrylic resin (Dentsply Repair Material, Dentsply Int, Inc, York, Pa) using three primers containing different functional monomers [UBar (UB), Sun Medical Co., Ltd., Shiga, Japan: Alloy Primer (AP) Kuraray Medical Inc., Okayama, Japan; and MR Bond (MRB) Tokyuyama Dental Corp., Tokyo, Japan] and two processing techniques (bench cure and pressure‐pot cure). Material and Methods: One hundred and twenty eight base metal alloy ingots were polished, air abraded, and ultrasonically cleaned. The control group was not primed. Specimens in the test groups were primed with one of the three metal primers. Autopolymerized acrylic resin material was bonded to the metal surfaces. Half the specimens were bench cured, and the other half were cured in a pressure pot. All specimens were stored in distilled water for 24 hours at 37°C. The specimens were debonded under tension at a crosshead speed of 0.05 cm/min. The forces at which the bond failed were noted. Data were analyzed using ANOVA. Fisher's PLSD post hoc test was used to determine significant differences (p < 0.05). Failure modes of each specimen were evaluated under a dissecting microscope. Results: Significant differences in bond strength were observed between combinations of primers, curing methods, and alloys. Primed sandblasted specimens that were pressure‐pot‐cured had significantly higher bond strengths than primed sandblasted bench‐cured specimens. The pressure‐pot‐curing method had a significant effect on bond strength of all specimens except Co‐Cr alloy primed with UB. The highest bond strength was observed for both Co‐Cr and Ni‐Cr alloys that were sandblasted, primed with MRB, and pressure‐pot cured. Co‐Cr alloys primed with UB had the lowest bond strength whether bench cured or pressure‐pot cured. Primed specimens generally experienced cohesive bond failures within the primer or acrylic resin. Nonprimed specimens generally experienced adhesive bond failures at the resin/metal interface. Conclusions: Within the limitations of this study, MRB provided the highest bond strength to both Ni‐Cr and Co‐Cr alloys. Generally, bond strength improved significantly when specimens were primed. Pressure‐pot curing, in most cases, resulted in higher bond strength than bench curing. The results of this in vitro study suggest that MRB metal primer can be used to increase bond strength of autopolymerized repair acrylic resin to base metal alloys. Curing autopolymerized acrylic under pressure potentially increases bond strength.     

Adhesion testing of a denture base resin with 5 casting alloys

PURPOSE: This study compared denture base resin shear bond strengths to silicoated Au-Pd, Au-Pd-Ag, Au-Ag-Pd-Cu, high-Pd, and Ni-Cr-Be alloys used to fabricate frameworks for hybrid implant prostheses. Microleakage between alloy and resin was also compared among groups after specimen fracture. MATERIALS AND METHODS: Twelve cylindrical specimens were cast for each alloy. Each specimen was made from a ring-shaped pattern (diameter [d] = 12 mm and height = 4 mm) and machined to achieve uniform hollow centers (d = 6.5 mm). Castings were abraded with 250-micron aluminum oxide and ultrasonically cleaned in distilled water before silicoating. Denture base resin was processed to the internal surfaces of the silicoated specimens. All specimens were thermocycled (1,000 cycles) between 4 degrees C and 50 degrees C, and placed in basic fuchsin dye for a week. A punch (d = 3.8 mm) driven at a cross-head speed of 0.5 mm/min was used to push out the resin specimens. The force required to cause failure was converted to the nominal shear bond strength for each specimen, and mean shear bond strengths for the 5 groups of specimens (N = 12) were compared using one-way analysis of variance and the Tukey-Kramer HSD multiple range test (alpha = 0.05). Six of the 12 debonded resin samples for each alloy were selected at random and evaluated for dye penetration. Using an 80-square grid, the percentage of dye penetration was evaluated with an optical microscope (x25) to determine the percentage of grid area penetrated by the dye. One-way analysis of variance was used to compare the degree of microleakage among groups. RESULTS: The mean resin-alloy shear bond strengths for the Au-Pd (9.6 +/- 3.7 MPa) and Au-Ag-Pd-Cu (9.2 +/- 1.5 MPa) alloys were significantly greater than mean resin-alloy shear bond strength for the Au-Pd-Ag alloy (5.6 +/- 1.9 MPa). No other significant differences in resin-alloy shear bond strengths were noted among the alloy groups. No significant differences were noted for dye penetration into the resin specimens bonded to any of the 5 alloys. The mean grid area penetrated by the dye was 25% when results for the alloys were pooled. CONCLUSIONS: Alloy type influences the shear bond strength of a denture base resin to silicoated alloys, but no difference in bond strength was found between Au-Pd, Au-Ag-Pd-Cu, high-Pd, and Ni-Cr-Be alloys. In addition, under the conditions of this study, all groups showed a similar degree of microleakage, which penetrated approximately 25% of the bonded specimen surface area.     

Effect of Surface Preparation Using Ethyl Acetate on the Shear Bond Strength of Repair Resin to Denture Base Resin

Purpose : This study evaluated the effect of using ethyl acetate as a surface preparation agent on the shear bond strength of repair resin to denture base resin.
Materials and Methods : The flat surfaces of a heat-processed denture base resin were prepared with one of the following: (1) without preparation, (2) 60-second application of ethyl acetate, (3) 120-second application of ethyl acetate, (4) 180-second application of ethyl acetate, and (5) 5-second application of dichloromethane. An autopolymerizing repair resin was applied. The specimens were then immersed in 37°C distilled water for 24 hours. The specimens in groups 1, 3, and 5 were thermocycled up to 10,000 times in water between 5 and 55°C with a 1-minute dwell time at each temperature. The shear bond strengths were determined at a crosshead speed of 1.0 mm/min (n = 10). The morphological changes in the repair surfaces after preparation were observed with a scanning electron microscope.
Results : The shear bond strengths of groups 3 and 5 were significantly higher than the other groups before thermocycling ( p < 0.05). The shear bond strengths of group 3 were significantly lower than those of group 5 after thermocycling ( p < 0.05). The scanning electron microscope (SEM) views showed that the dissolution progressed deeper with the preparation duration.
Conclusions : The 120-second surface application of ethyl acetate enhanced the shear bond strength between the repair resin and the denture base resin, although the bond durability was inferior to that of the conventional surface preparation.     

Evaluation of two dual-functional primers and a tribochemical surface modification system applied to the bonding of an indirect composite resin to metals

We evaluated the effects of two dual-functional primers and a tribochemical surface modification system on the bond strength between an indirect composite resin and gold alloy or titanium. Disk specimens (diameter, 10 mm; thickness, 2.5 mm) were cast from type 4 gold alloy and commercially pure titanium. The specimens were wetground to a final surface finish using 600-grit silicone carbide paper. The specimens were then air-dried and treated using the following four bonding systems: (1) air-abrasion with 50–70 μm alumina, (2) system 1 + alloy primer, (3) system 1 + metal link primer, and (4) tribochemical silica/silane coating (Rocatec). A light-polymerizing indirect composite resin (Ceramage) was applied to each metal specimen and polymerized according to the manufacturer’s specifications. Shear bond strengths (MPa) were determined both before and after thermocycling (4°C and 60°C for 1 min each for 20 000 cycles). The values were compared using analysis of variance, post hoc Scheffe tests, and Mann-Whitney U tests (alpha = 0.05). The strengths decreased after thermocycling for all combinations. For both gold alloy and titanium, the bond strength with air-abrasion only was statistically lower than that with the other three modification methods after thermocycling. Titanium exhibited a significantly higher value (13.4 MPa) than gold alloy (10.5 MPa) with the air. abrasion and alloy primer system. Treatment with the tribochemical system or air abrasion followed by treatment with dual-functional priming agents was found to be effective for enhancement of the bonding between the indirect composite and gold alloy or titanium.     

Evaluation of three silicoating methods for resin-bonded prostheses

Three different methods of increasing the bond strength of resin to metal were tested: the original Silicoater technique, the Silicoater MD technique, and the Rocatec system. Metals used for the resin-bonded prostheses were gold, a cobalt-chromium (Co-Cr) alloy, and titanium. Silicoating increased the bond strength to sandblasted specimens. The original Silicoater technique produced the highest bond strengths, especially when used with the Co-Cr alloy and titanium. The Silicoater MD technique showed the lowest bond strengths for all of the test metals. Storage for 7 days with protective film on the silicoated surface did not affect the bond strength, as compared with specimens bonded immediately. The retention of the resin to the gold specimens (Rocatec system) decreased after thermocycling, but retention to the Co-Cr alloy and titanium was not affected. Various resin cements were tested and showed the same retention with the exception of Microfill Pontic, which gave a weaker bond. Scanning electron microscope (SEM) and energy-dispersive X-ray analysis (EDAX) of the specimens before and after the measurements gave no clear explanation of the differences in bond strengths between the test metals. However, it was concluded that silicoating of the metal surfaces contributed to the retention of the resin by chemical action, as no differences in adaptation of the resin to the metal were seen between specimens pretreated by sandblasting and those which were also silicoated.     

Bonding and wear characteristics of a tri-n-butylborane initiated adhesive resin filled with pre-polymerized composite particles

This study evaluated the wear characteristics and bonding to silver-palladium-copper-gold (Ag-Pd-Cu-Au) alloy of an acrylic resin that was filled with pre-polymerized composite particles and initiated with tri-n-butylborane (TBB) derivative (Bondfill). Three methyl methacrylate (MMA)-based resins (Bondfill, Super-Bond, and Multi-Bond II) and a microfilled composite restorative material (Metafil C) were assessed. Disk specimens were cast from the alloy and were air-abraded with alumina. The disks were bonded with nine bonding systems selected from two priming and three luting agents. Shear bond strengths were measured before and after thermocycling. Bond strength varied from 2.2 MPa to 28.2 MPa. Three systems based on thione primers (Metaltite and V-Primer) and TBB-initiated resins (Bondfill and Super-Bond) had the highest bond strength after thermocycling (15.9-20.4 MPa). The toothbrush-dentifrice abrasion test showed that the Metafil C material was the most wear-resistant, followed by Bondfill and Super-Bond. In conclusion, Bondfill resin is an alternative to Super-Bond resin for luting metallic restorations and for restoring tooth defects. However, care is required in selecting appropriate clinical cases.