Comparison of bond strengths of three denture base resins to treated nickel-chromium-beryllium alloy

Evaluation of the Effectiveness of Semolina in Improving the Bond Strength of Metal Alloys and Acrylic Resins for the Fabrication of Hybrid Prostheses for Implant Restoration: An In Vitro Study

Introduction Fixed prosthodontic solutions for restorations of multiple implants are often done using acrylic-metal hybrid prosthesis. These restorations have a high failure rate due to poor bond strength between metal and acrylic, despite using digital attachments and primers. This study has been done to demonstrate an economical yet effective method of increasing shear bond strength between acrylic and metal. Materials and methods Disc specimens of 10 mm diameter and 2 mm thickness were designed using the Meshmixer version 3.5 software (Autodesk Inc., San Rafael, USA). The standard tessellation (STL) file was imported and sent for direct metal laser sintering (DMLS) in cobalt-chromium (CoCr), titanium (Ti), and wax milling. The groups were defined. Ten samples were included in each group. Group 1: Conventional Casting in CoCr; Group 2: Conventional Casting with Opaquer (CoCr); Group 3: DMLS CoCr; Group 4: DMLS CoCr with Opaquer; Group 5: DMLS Ti; Group 6: DMLS Ti with Opaquer; Group 7: Casting with Semolina (CoCr); and Group 8: Casting with Semolina and Opaquer (CoCr). Wax-up was performed using double wax sheet thickness of modeling wax. Flasking and acrylization were done using the injection moulding technique. A universal testing machine was used for shear bond strength. Results were tabulated and statistical analysis was done using IBM SPSS Statistics for Windows (IBM Corp., Armonk, USA). The Shapiro-Wilk test was done to confirm the normality of the data, followed by the one-way analysis of variance (ANOVA) test to compare the shear bond strength between metal alloys and heat cure acrylic resin.  Results The one-way ANOVA results reveal significant differences in bond strengths among the various groups. Conventional Casting with Opaquer showed no significant difference (p=0.335), but there were notable improvements in bond strength when compared to DMLS CoCr, DMLS CoCr with Opaquer, DMLS Ti, DMLS Ti with Opaquer, Semolina, and Semolina with Opaquer, with DMLS Ti having the largest mean difference (3.368). Conventional Casting with Opaquer significantly outperformed all groups, especially Semolina, which showed the highest mean difference (7.558). Similar trends were seen with DMLS CoCr and DMLS Ti, where Semolina consistently demonstrated superior bond strength. Overall, Semolina produced the highest bond strengths across all conditions. These results underscore the importance of material selection and treatment in enhancing bond strength. Conclusion Semolina can be used as an economical and reliable method to increase the shear bond strength between acrylic and metal bonding. Its ability to burn out during dewaxing without any remains or remnants in mould deems it a useful material for increasing mechanical bonding.

Effect of ultraviolet irradiation treatment on shear bond strength between polymethyl methacrylate and cobalt-chromium-molybdenum alloy

We aimed to elucidate the effects of ultraviolet (UV) irradiation on the shear bond strength (SBS) between heat-cured polymethyl methacrylate (PMMA) and a Co-Cr-Mo alloy. Disk-shaped Co-Cr-Mo alloy prepared by casting were subjected to different UV treatment times (0, 15, and 30 min). To determine the effect of UV treatment on surface properties of the alloy, surface roughness, wettability, and chemical compositions were analyzed. To evaluate the SBS, cylindrical PMMA was bonded to the UV-treated alloy, and subsequently subjected to the SBS test after 24 h of storage at room temperature or following 10,000 thermal cycles (n=10/group). After the UV treatment, the surface roughness remained unchanged, but oxidation resulted in the surface exhibiting greater hydrophilic characteristics. The UV-treated group showed significantly higher SBS values than those of the non-treated group (p<0.001). These results suggested that UV treatment-mediated oxidation improved the bond strength between PMMA and Co-Cr-Mo alloy.

Effect of Surface Treatments on Shear Bond Strength of Polyetheretherketone to Autopolymerizing Resin

These days, new prosthodontic materials are appearing with the development of digitalization. Among these, the use of polyetheretherketone (PEEK) as the clasp of removable partial dentures has been proposed. The adhesive strength between the PEEK and acrylic resin influences the probability of denture fracture. To investigate the effect of PEEK surface treatments on the shear bond strength to acrylic resin, five surface treatment conditions of PEEK were analyzed: 1. no treatment; 2. ceramic primer application; 3. Al₂O₃ sandblasting; 4. Rocatec; and 5. Rocatec with ceramic primer application, comparing with a metal primer-treated Co-Cr alloy. Two kinds of autopolymerizing resin (Unifast II and Palapress Vario) were used as bonding materials. The specimens were evaluated to determine the bond strength. Rocatec treatment with ceramic primer application yielded the highest bond strengths (12.71 MPa and 15.32 MPa, respectively, for Unifast II and Palapress Vario). When compared to a metal primer-treated Co-Cr alloy, the bond strength of PEEK to Unifast II was similar, whereas it was about 60% of that to Palapress Vario. Rocatec treatment, combined with ceramic primer, showed the highest bond strength of PEEK to acrylic resin. Treatment of PEEK will enable its use as the clasp of removable dentures and the fixation of PEEK prostheses.

The Effect of Artificial Aging on The Bond Strength of Heat-activated Acrylic Resin to Surface-treated Nickel-chromium-beryllium Alloy

PURPOSE

The debonding load of heat-activated polymethylmethacrylate (PMMA) denture base resin material to a nickel-chromium-beryllium (Ni-Cr-Be) alloy conditioned by three different surface treatments and utilizing two different commercial bonding systems was investigated.

MATERIALS AND METHODS

Denture resin (Lucitone-199) was bonded to Ni-Cr-Be alloy specimens treated with Metal Primer II, the Rocatec system with opaquer and the Rocatec system without opaquer. Denture base resin specimens bonded to non-treated sandblasted Ni-Cr-Be alloy were used as controls. Twenty samples for each treatment condition (80 specimens) were tested. The 80 specimens were divided into two categories, thermocycled and non-thermocycled, containing four groups of ten specimens each. The non-thermocycled specimens were tested after 48 hours' storage in room temperature water. The thermocycled specimens were tested after 2,000 cycles in 4°C and 55°C water baths. The debonding load was calculated in Newtons (N), and collected data were subjected by non parametric test Kruskal-Wallis One Way Analysis of Variance on Ranks and Dunn's post hoc test at the α = 0.05.

RESULTS

The Metal Primer II and Rocatec system without opaquer groups produced significantly higher bond strengths (119.9 and 67.6 N), respectively, than did the sandblasted and Rocatec system with opaquer groups, where the bond strengths were 2.6 N and 0 N, respectively. The Metal Primer II was significantly different from all other groups (P<0.05). The bond strengths of all groups were significantly decreased (P<0.05) after thermocycling.

CONCLUSIONS

Although thermocycling had a detrimental effect on the debonding load of all surface treatments tested, the Metal Primer II system provided higher values among all bonding systems tested, before and after thermocycling.

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 degrees 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.

Effect of surface preparation on the failure load of a highly filled composite resin bonded to a denture base resin

PURPOSE

The purpose of this study was to evaluate the effect of the surface preparation on the maximum fracture load value of a highly filled gingival shade composite resin bonded to a denture base resin.

MATERIALS AND METHODS

Block specimens were prepared from a heat-processed denture base resin and divided into five groups. The flat surfaces of the specimens were abraded with 400-grit silicon carbide paper, then prepared in one of the following ways: (1) without preparation (group 1); (2) application of silane coupling agent (group 2); (3) application of dichloromethane (group 3); (4) application of dichloromethane following the silane coupling agent (group 4); or (5) tribochemical silica coating (group 5). A highly filled gingival shade composite resin was applied (area diameter= 5 mm) and polymerized with a light polymerizing unit. Specimens made entirely of heat-processed denture base resin were also fabricated as references (group 6). The halves of the specimens of groups 4, 5, and 6 were thermocycled up to 10,000 times in water between 5 degrees C and 55 degrees C with a 1-minute dwell time at each temperature. Shear testing was performed in a universal testing machine at a crosshead speed of 1 mm/min, and the maximum fracture load values were determined (n = 10).

RESULTS

The maximum fracture load values of the highly filled gingival shade composite resin bonded to the denture base resin for all preparation groups were significantly enhanced before thermocycling (p < 0.05). Group 5 exhibited the greatest fracture load value, followed by group 4, compared to the other groups (p < 0.05), however, the fracture load values significantly decreased for these groups after thermocycling (p < 0.05), whereas the fracture load value of group 6 did not decrease (p > 0.05).

CONCLUSIONS

Tribochemical silica coating and the application of dichloromethane after the silane coupling agent were effective surface preparations for the bonding of a highly filled gingival shade composite resin to a denture base resin, however, the bond durability of these treatments may be insufficient.

Spark erosion as a metal–resin bonding system

PURPOSE

Resin to metal bond strength of two commercial and one experimental metal-resin bonding system for crown and bridge veneer composites was evaluated.

MATERIALS AND METHODS

All specimens were prepared and tested according to ISO 10477 Amendment 1. A high precious alloy (HPA), a Co/Cr-alloy (Co/Cr) and pure titanium (Ti) were wet-ground to a final surface finish of 800 grit and air-dried. Twenty specimens of each metal were treated with Rocatec (RO), 20 with a Silano-Pen (SP), and 20 with the experimental spark-erosion (SE) bonding system. A light-curing opaque and a crown and bridge veneer composite were applied to each metal specimen. Ten specimens of each metal and bonding system were stored in water for 24h at 37 degrees C, 10 were thermocycled (TC) 5000 times in a water-bath between +5 and +55 degrees C prior to measuring shear bond strength (SBS). Scanning electron microscopy (SEM) was used to examine the treated metal surfaces.

RESULTS

After 24h SE generated significantly higher SBS values on Ti than RO (p<0.05). SP revealed the highest SBS for Co/Cr. After TC significant decreases occurred for RO on HPA, for SP on Co/Cr and Ti, and for SP on Ti. SE revealed the highest mean bond values for all metals. These results and SEM proved that no sandblasting is required for SE to obtain good bond strength.

SIGNIFICANCE

The experimental spark-erosion bonding system is an easy and very effective method for surface-treating alloys to obtain high SBS values for crown and bridge veneer composites.

Effects of a metal etchant and two primers on resin bonding durability to titanium

The purpose of this study was to investigate the efficacy of an etchant in titanium bonding. The aqueous etchant consisted of 0, 5, or 10 wt% ammonium hydrogen fluoride (AHF) in combination with 0, 0.03, 0.3, or 3 wt% cupric chloride (CC). The two primers used were a phosphate-methacrylate primer and a thiophosphate-methacrylate primer, and two self-curing resins (Super-Bond C&B and MT) were employed as luting agents. Disk specimens were cast with a commercially pure titanium. The surface was air-abraded with 50 microm alumina, etched for 10 s, rinsed with water, and then air-dried. The primer was applied to the bonding area (5 mm in diameter), and an acrylic rod was bonded to the specimen with the luting agent. Shear bond strengths were evaluated after 24 h of water storage and following 10,000 thermocycles (4 degrees C and 60 degrees C). The post-thermocycling bond strength was significantly increased with each of the two primers compared with the unprimed controls. The etchant containing 5 wt% AHF and 0.3 wt% CC further increased their durability, and microscopic observation revealed that innumerable submicron crystals were created on the etched specimen. The present results suggest that the chemical etching improved the resin bonding durability to titanium in combination with the primer used.

Tensile bond strengths of composites to a gold-palladium alloy after thermal cycling

STATEMENT OF PROBLEM

Many different materials and methods have been used to fabricate or repair veneer facings with composites, but only a few of these have been studied.

PURPOSE

This study compared the tensile bond strengths of composites to a gold-palladium alloy with the use of several surface treatment methods.

MATERIAL AND METHODS

Forty alloy specimens were cast in Eclipse (52% gold and 37.5% palladium) in the form of truncated cones. These specimens were divided equally into 4 groups. In group I, the bonding surfaces of the metal cones were treated with Silicoater MD. Truncated cones of Dentacolor composite were bonded to the metal surfaces and light-polymerized. In group II, the bonding surfaces of the metal cones were air-particle abraded with 50 microm aluminum oxide and coated with C&B Metabond. Truncated cones of Epic-TMPT composite were bonded to the metal surfaces and light-polymerized. In group III, the bonding surfaces of the metal cones were air-particle abraded with CoJet-Sand. Truncated cones of Pertac-Hybrid composite were bonded to the metal surfaces and light-polymerized. In group IV, the bonding surfaces of the metal cones were air-particle abraded with CoJet-Sand. Truncated cones of Visio-Gem were bonded to the metal surfaces and light-polymerized. After 24 hours of water immersion at 37 degrees C and 1000 thermal cycles in water at 5 degrees C and 55 degrees C, tensile forces were applied to all specimens with a universal testing machine. Analysis of variance was applied to the data (P<.05), and differences among means were determined with a Tukey-Kramer interval of 5.4 MPa.

RESULTS

Tensile bond strengths in MPa were as follows: Dentacolor, 14 +/- 5; Epic-TMPT, 12 +/- 4; Pertac-Hybrid, 13 +/- 5; and Visio-Gem, 18 +/- 4. The tensile bond strength of Visio-Gem was significantly higher than that of Epic-TMPT, but no differences were found among Dentacolor, Pertac-Hybrid, and Epic-TMPT (P<.05).

CONCLUSION

Within the limitations of this study, all 4 bonding systems tested produced high bond strengths between composites and a gold-palladium alloy after thermal cycling.

4-META use in dentistry: a literature review

4-META (4-methacryloyloxyethy trimellitate anhydride) was invented and patented in Japan in January 1979 and patented in the United States in April 1979. For the first 8 years, 4-META dental products (manufactured by Sun Medical Co, Kyoto, Japan) were not readily available in North America. Most of the early research therefore was done in Japan and reported in Japanese. A second wave of products (manufactured by Parkell, Farmingdale, N.Y.) became available in the United States in 1987, which precipitated research in English. This article is a chronological review of the literature published between 1978 and 1998 on 4-META dental adhesive materials. Thirteen commercial products are reviewed in terms of their physical strength; research on the mechanisms of 4-META action and the biocompatibility of 4 META was excluded.