Relationship between sandblasting and composite resin-alloy bond strength by a silica coating

Which metal surface treatment improves the bond strength between metal alloys and acrylic resin in removable partial dentures? A systematic review

STATEMENT OF PROBLEM

The union of the metal removable partial denture framework to the heat polymerized acrylic resin is related to prosthesis longevity. However, methods to enhance this bond are not clear to clinicians and dental laboratory technicians.

PURPOSE

The purpose of this systematic review was to identify which metal surface treatments best increase the bond strength between heat polymerized acrylic resin and removable partial denture alloys.

MATERIAL AND METHODS

This review was carried out following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and registered in the International Prospective Registry of Systematic Reviews (PROSPERO) database (CRD42022384926). Electronic searches were carried out independently, by 3 examiners in Medline/PubMed, Scopus, and Web of Science databases, and in the nonpeer-reviewed literature via ProQuest.

RESULTS

The electronic searches resulted in 4143 articles, with 4055 after removing duplicates. After reading the titles and abstracts, 37 articles were selected for reading in full-text version, from which 6 articles were included. All studies evaluated materials for conventional acrylic resin denture base (heat polymerized), processed by water bath, bonded to metal. For the metal framework alloys, cobalt chromium (Co-Cr) alloys were used in 2 studies, titanium (Ti) in 2 studies, and Co-Cr and Ti in the other 2 studies. Different metal surface treatments were used as airborne-particle abrasion with aluminum oxide (particle sizes of 50 µm, 110 µm, and 250 µm) followed by the primer application and the isolated use of the primer, compared to the absence of isolated intervention or airborne-particle abrasion of the metal surface. Among the different primers used, those based on 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) showed the highest acrylic resin-to-metal bond strength values.

CONCLUSIONS

Airborne-particle abrading the metal with Al2O3 followed by applying a 10-MDP-based primer, increased the bond strength between metal framework alloys and heat polymerized acrylic resin denture base material.

Oxygen Plasma Improved Shear Strength of Bonding between Zirconia and Composite Resin

Improving the strength of the bonding of zirconia to composite resins remains a challenge in dental restorations. The purpose of this study was to evaluate the shear strength of the bonding of zirconia to composite resins, thereby verifying the hypothesis that as the power of the non-thermal oxygen plasma increases, the bonding strength of the plasma-treated zirconia is increased. The effects of the oxygen plasma power (100, 200, and 400 W) on the surface structure, chemical composition, and hydrophilicity of the zirconia and the strength of the bonding between zirconia and composite resin were investigated. As a result, after different plasma power treatments, the surface structure and phase composition of zirconia were not different from those of zirconia without treatment. However, the oxygen plasma treatment not only reduced carbon adsorption but also greatly increased the hydrophilicity of the zirconia surface. More importantly, the strength of the bonding between the plasma-treated zirconia and composite resin was significantly higher than that in the corresponding control group without plasma treatment. Regardless of whether the zirconia was pristine or sandblasted, the higher the plasma power, the greater the bond strength obtained. The conclusion is that the oxygen plasma treatment of zirconia can effectively improve the strength of the bonding between the zirconia and composite resin without damaging the microstructure and phase composition of the zirconia.

Effect of Laser Etching and Spark Erosion on Retention and Resistance of Partial Veneer Crown Copings Luted with Adhesive Resin Cement

Purpose:

There has been less focus on methods to improve the clinical performance of partial veneer crowns. In this study, we wanted to explore the potential of two new surface treatment modalities (laser etching and spark erosion) for improving the longevity of partial veneer crowns.

Material and Methods:

Conventional partial veneer crown preparation was done on 90 extracted premolars by a single operator. All the samples used in the study were divided into three groups. Group A were samples to be treated by sandblasting alone, Group B were samples to be treated by sandblasting followed by laser etching, and Group C were samples to be treated by sandblasting followed by spark erosion. Each group consisted of two Sub Groups: Sub Group I-Retention test group, Sub Group: II-Resistance test group. The prepared teeth were randomly allotted to the three groups and subgroups using lot method. Partial veneer crown copings were fabricated for testing retention and resistance. Castings in each subgroup were luted with resin cement to their respective tooth preparations. Retention and resistance testing of samples were done with the use of an Instron Universal testing machine.

Results:

The two surface treatments, laser etching and spark erosion (Groups B and C) of metal copings significantly improved the retention and resistance compared to sandblasted surfaces alone (P ≤ 0.05). Retention and resistance of copings which were sandblasted and spark eroded (Group C) were found to be highest among the three groups (P ≤ 0.05).

Conclusion:

Within the limitation of this study, it can be concluded that the combination of spark erosion and sandblasting significantly improves the retention and resistance values of partial veneer crown. This study helps to provide better knowledge about the surface treatment required for success of partial veneer crowns.

Effect of different surface treatments and retainer designs on the retention of posterior Pd-Ag porcelain-fused-to-metal resin-bonded fixed partial dentures

The aim of this study was to investigate the adhesive property of palladium-silver alloy (Pd-Ag) and the simulated clinical performance of Pd-Ag porcelain-fused-to-metal (PFM), resin-bonded, fixed partial dentures (RBFPDs). A total of 40 Pd-Ag discs (diameter=5 mm) were prepared and divided into the following four groups (n=10): a) No sandblasting, used as a control; and b, 50 µm; c, 110 µm; and d, 250 µm aluminum oxide (Al₂O₃) particles, respectively. Another 50 discs were pre-sandblasted and divided into five groups (n=10) subjected to different treatments: e) Sandblasting, used as a control; f) silane; g) alloy primer; h) silica coating + silane and i) silica coating + alloy primer. All 90 discs were bonded to enamel with Panavia F 2.0 and then subjected to shear bond strength (SBS) testing. The fracture surfaces were examined by scanning electron microscopy. Next, 40 missing maxillary second premolar models were restored with one of the four following RBFPD designs (n=10): I) A premolar occlusal bar combined with molar double rests (MDR); II) both occlusal bars with a wing (OBB); III) a premolar occlusal bar combined with a molar dental band (MDB); and IV) two single rests adjacent to the edentulous space with a wing (SRB) used as a control. All specimens were aged with thermal cycling and mechanical loading. Subsequently, they were loaded until broken. The data were analyzed by one-way analysis of variance. Al₂O₃ (250 µm) abrasion provided the highest SBS (P<0.05). The alloy primer and silica + silane exhibited increased SBS. Furthermore, fracture analysis revealed that the failure mode varied among the different treatments. Whereas MDB exhibited the highest retention (P<0.05), that of OBB was greater than that of MDR (P<0.05), and the control exhibited the lowest retention. Abrasion with Al₂O₃ (250 µm) effectively increased the adhesive property of Pd-Ag. Additionally, treatment with the alloy primer and silica coating + silane was able to increase the adhesive property of abraded Pd-Ag. Under the present conditions, all three modified retainer types provided improved outcomes for Pd-Ag PFM RBFPDs compared with the control.

Evaluation and comparison of the effect of different surface treatment modifications on the shear bond strength of a resin cement to titanium: An in vitro study

The purpose of this study was to evaluate and compare the effect of grit blasting, chemical treatment, and application of alloy primer combinations on the shear bond strength (SBS) of a self-cure resin cement to titanium surface.

Evaluation of shear bond strength of composite resin bonded to alloy treated with sandblasting and electrolytic etching

Conservation of natural tooth structure precipitated the emergence of resin-retained fixed partial dentures. The weakest link in this modality is the bond between resin cement and alloy of the retainer. Various alloy surface treatment have been recommended to improve alloy-resin bond. This in vitro study was carried out to observe changes in the Nickel-Chromium alloy (Wiron 99, Bego) surface following sandblasting or electrolytic etching treatment by scanning electron microscope (SEM) and to evaluate the shear bond strength of a resin luting cement bonded to the surface treated alloy. 80 alloy blocks were cast and divided into four groups of 20 each. In groups-A & B, the test surfaces were treated by sandblasting with 50 and 250 μm sized aluminium oxide particles respectively. In groups-C & D, the test surfaces were first treated by sandblasting with 50 and 250 μm sized aluminium oxide particles respectively followed by electrolytic etching. Test surfaces were observed under SEM at 1,000× magnification. Two alloy blocks of each group were luted together by a resin luting cement (Rely X, 3M) and their shear bond strength was tested. The mean shear bond strength in MPa of groups-A to D were 6.44 (±0.74), 8.18 (±0.51), 14.45 (±0.59) and 17.43 (±1.20) respectively. Group-D showed bond strength that is more than clinically acceptable bond strength. It is recommended that before luting resin-retained fixed partial dentures, the fitting surface of the retainer should be electrolytically etched to achieve adequate micromechanical retention.

An In vitro Evaluation of Flexural Bond Strength of Indirect Composites Fused to Metal

With the advent of newer indirect composite resin materials for crown and bridge prosthesis, it has become imperative to evaluate their strength to serve as long term replacements as a substitute to metal ceramic restorations. This study aimed to evaluate and compare the flexural bond strength of three composite resin veneering material to metal, cured by different methods. Specimen were fabricated with pattern resin by duplicating it with machined metal die and divided into three groups. Three composite resin materials were used in this study. Group (A) received Adoro, Group (B) received Targis and Group (C) received Tescera. The bond strength of all specimens was tested with Lloyd's universal testing machine under three point loading. The highest values for fracture resistance were displayed by light, heat and pressure cured composites followed by composites cured using a temperature of 104 °C and composites with curing temperature of 95 °C. The results indicate that there is a significant difference between the three groups, with the Tescera group specimens exhibiting the highest flexural bond strength. Of the other two groups, Adoro group exhibited higher flexural bond strength than Targis group. The results of this study suggest that Tescera group with curing temperature of 130 °C and pressure of 80 Psi, cured with metal halide unit exhibited the highest flexural bond strength when compared to Adoro and Targis groups.

Effect of different airborne-particle abrasion/bonding agent combinations on the bond strength of a resin cement to a base metal alloy

STATEMENT OF PROBLEM

Investigation of surface treatments to improve the bond of resin cements to metals may contribute to the longevity of metal ceramic restorations.

PURPOSE

The purpose of this study was to evaluate the efficacy of surface treatments on the shear bond strength (SBS) of a resin cement to nickel-chromium (NiCr) alloy.

MATERIAL AND METHODS

Eighty cast NiCr alloy disks (9 × 3 mm) were divided into 8 groups (n=10), which received 1 of the following surface treatments: 1) 50 µm Al(2)O(3) particles + silane; 2) 120 µm Al(2)O(3) + silane; 3) 30 µm silica-modified Al(2)O(3) (Cojet Sand) + silane; 4) 120 µm Al(2)O(3) followed by 110 µm silica-modified Al(2)O(3) (Rocatec) + silane; 5) 50 µm Al(2)O(3) + metal primer; 6) 120 µm Al(2)O(3) + metal primer; 7) 30 µm silica-modified Al(2)O(3) (Cojet Sand) + metal primer; and 8) 120 µm Al(2)O(3) followed by 110 µm silica-modified Al(2)O(3) (Rocatec) + metal primer. The silane was RelyX Ceramic Primer and the metal primer Alloy Primer. RelyX ARC resin cement was bonded to NiCr alloy surfaces. Specimens were thermally cycled before shear mode testing. Data (MPa) were analyzed by 1-way ANOVA and the Tukey test (α=.05). Failure mode was determined with a stereomicroscope (×20).

RESULTS

The results revealed that surface treatment was significant (P<.001). There was no significant difference between 50 µm and 120 µm Al(2)O(3) particles, regardless of the bonding agent used (silane or metal primer). Cojet Sand provided lower SBS than Rocatec, both in the groups treated with silane (P<.001) and metal primer (P<.01). No significant difference was observed between silane and metal primer in the groups abraded with 50 µm and 120 µm Al(2)O(3) particles. Metal primer decreased the SBS of both Cojet Sand and Rocatec groups (P<.001). Rocatec + silane had the highest SBS and Cojet Sand + metal primer the lowest. All groups presented 100% adhesive failure.

CONCLUSIONS

Particle size influenced SBS only in the groups abraded with silica-modified Al(2)O(3). The bonding agent did not affect SBS in the groups abraded with Al(2)O(3). Alloy Primer was not chemically compatible with silica-modified Al(2)O(3). Both mechanical (particle size) and chemical (silica/silane interaction) factors contributed to the high SBS of Rocatec + silane.

Shear bond strength between autopolymerizing acrylic resin and Co-Cr alloy using different primers

This study aimed to examine the shear bond strength between cobalt chromium alloy and autopolymerizing acrylic resin using experimental primers containing 5, 10, and 15 wt% of 4-methacryloxyethyl trimellitic anhydride or 1, 2, and 3 wt% of 3-methacryloxypropyl-trimethoxysilane comparison to 5 commercial primers (ML primers, Alloy primer, Metal/Zirconia primer, Monobond S, and Monobond plus). Sixty alloy specimens were sandblasted and treated with each primer before bonded with an acrylic resin. The control group was not primed. The shear bond strengths were tested and statistically compared. Specimens treated with commercial primers significantly increased the shear bond strength of acrylic resin to cobalt chromium alloy (p<0.05). The highest shear bond strength was found in the Alloy primer group. Among experimental group, using 10 wt% of 4-methacryloxyethyl trimellitic anhydride -or 2 wt% of 3-methacryloxypropyltrimethoxysilane enhanced highest shear bond strength. The experimental and commercial primers in this study all improved bonding of acrylic resin to cobalt chromium alloy.

Effect of laser welding on the titanium composite tensile bond strength

The aim of this study was to analyze the shear bond strength between commercially pure titanium, with and without laser welding, after airbone-particle abrasion (Al(2)O(3)) and 2 indirect composites. Sixty-four specimens were cast and divided into 2 groups with and without laser welding. Each group was divided in 4 subgroups, related to Al(2)O(3) grain size: A - 250 microm; B - 180 microm; C- 110 microm; and D - 50 microm. Composite rings were formed around the rods and light polymerized using UniXS unit. Specimens were invested and their shear bond strength at failure was measured with a universal testing machine at a crosshead speed of 2.0 mm/min. Statistical analysis was carried out with ANOVA and Tukey's test (alpha=0.05). The highest bond strength means were recorded in 250 microm group without laser welding. The lowest shear bond strength means were recorded in 50 microm group with laser welding. Statistically significant differences (p<0.05) were found between all groups. In conclusion, airborne particle abrasion yielded significantly lower bond strength as the Al(2)O(3) particle size decreased. Shear bond strength decreased in the laser welded specimens.

Effect of surface treatments on the bond strength of a resin cement to commercially pure titanium

Investigation of the effectiveness of surface treatments that promote a strong bond strength of resin cements to metals can contribute significantly to the longevity of metal-ceramic restorations. This study evaluated the effect of surface treatments on the shear bond strength (SBS) of a resin cement to commercially pure titanium (CP Ti). Ninety cast CP Ti discs were divided into 3 groups (n=30), which received one of the following airborne-particle abrasion conditions: (1) 50 ?m Al2O3 particles; (2) 30 ?m silica-modified Al2O3 particles (Cojet Sand); (3) 110 ?m silica-modified Al2O3 particles (Rocatec). For each airborne-particle abrasion condition, the following post-airborne-particle abrasion treatments were used (n=10): (1) none; (2) adhesive Adper Single Bond 2; (3) silane RelyX Ceramic Primer. RelyX ARC resin cement was bonded to CP Ti surfaces. All specimens were thermally cycled before being tested in shear mode. Failure mode was determined. The best association was Rocatec plus silane. All groups showed 100% adhesive failure. There were combinations that promote higher SBS than the protocol recommended by the manufacturer of RelyX ARC.

Durability of the bond between resin composite cores and prefabricated posts

OBJECTIVES

This study evaluated the effect of post surface treatment and of storage condition on the bond between resin composite cores (Clearfil Core) and posts of titanium alloy (Fysika), silica-zircon fiber reinforced epoxy resin (SiliciumPost), and zirconia (CosmoPost).

MATERIAL AND METHODS

In the experimental groups, the coronal part of each post received sandblasting or tribochemical silicate-coating (CoJet) treatment. The coronal part of each post was embedded in a cylinder of resin composite core material with the aid of a fixation apparatus. After 15 min, the specimen was freed from the mold and stored in de-ionized water. The axial tensile strength (ATS) of posts was determined in a Universal Testing Machine when extracting the posts from the resin composite cores after: 1) 14 d water storage at 37°C, 2) 14 d water storage at 37°C followed by thermal cycling (6,000 cycles between 5°C and 55°C), or 3) 1 year water storage at 37°C. The results were statistically analyzed by three-way factorial ANOVA and Newman-Keuls' multiple range test.

RESULTS

The ATS values were generally higher for Fysika posts and SiliciumPost posts than for CosmoPost posts. Surface treatment effectively improved the ATS values of Fysika posts and SiliciumPost posts, but not those of CosmoPost posts. Thermal cycling or long-term water storage had only minimal effect on the ATS values of the posts.

CONCLUSION

Bonding of resin composite cores to the posts depended more on the material of the post and the surface treatment of posts than on the storage condition.

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 mum 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 degrees C and 60 degrees 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.

Shear bond strength of composite resin to titanium according to various surface treatments

STATEMENT OF PROBLEM

When veneering composite resin-metal restoration is prepared, the fact that bond strength between Ti and composite resin is relatively weak should be considered.

PURPOSE

The purpose of this study is to evaluate the shear bond strength between the veneering composite resin and commercial pure (CP) Ti / Ti-6Al-4V alloy according to the method of surface treatment.

MATERIAL AND METHODS

The disks were cast by two types of metal. Their surfaces were treated by sandblasting, metal conditioner, TiN coating and silicoating respectively. After surface treatment, the disks were veneered by composite resin (Tescera™, Bisco, USA) which is 5 mm in diameter and 3 mm in thickness. The specimens were stored in water at 25℃ for 24 hours, and then evaluated for their shear bond strength by universal testing machine (STM-5®, United Calibration, USA). These values were statistically analyzed.

RESULTS

1. All methods of surface treatment were used in this study satisfied the requirements of ISO 10477 which is the standard of polymer-based crown and bridge materials. 2. The metal conditioner treated group showed the highest value in shear bond strength of CP Ti, silicoated group, TiN coated group, sandblasted group, in following order. 3. The silicoated group showed the highest value in shear bond strength of Ti-6Al-4V alloy, metal conditioner treated group, sandblasted group, TiN coated group, in following order.

CONCLUSION

Within the limitations of this study, all methods of surface treatment used in this study are clinically available.

Adhesive bonding of resin composite to various Ni-Cr alloy surfaces using different metal conditioners and a surface modification system

PURPOSE

This study evaluated the effect of three metal conditioners [Metal Photo Primer (MPP), Cesead II Opaque Primer (OP), Targis Link (TL)], and one surface modification system [Siloc (S)] on the shear bond strength (SBS) of a prosthetic composite material to Ni-Cr alloy.

MATERIALS AND METHODS

Rivet-shaped specimens were cast, and three surface treatments were evaluated: Polishing (P); sandblasting with either 50 microm (50SB) or 250 microm (250SB) Al(2)O(3). All products were applied to half of the specimens, while the other half remained without the materials. Veneering resin composite (8-mm diameter, 2-mm thick) was applied and light-exposed for 90 seconds in a laboratory light-curing unit. The specimens were stored in water at 37 degrees C for 24 hours, and half were subjected to 500 thermal cycles consisting of water baths at 4 degrees C and 60 degrees C. All specimens were submitted to SBS test (0.5 mm/min) until failure. Failure patterns were determined using optical and scanning electron microscope (SEM) analysis. Data were analyzed by ANOVA and post hoc Tukey's test (preset alpha of 5%).

RESULTS

The SBS values of OP and TL groups were higher than those of MPP and S within the 50SB treatment (p < 0.05). No significant difference in SBS was noted between OP and TL as well as between MPP and S. On the other hand, no significant differences were found among conditioners within the 250SB group (p > 0.05). The SBS values of MPP, OP, and S from the 250SB group were higher than those from 50SB (p < 0.05). No significant difference in SBS was noted among most groups with conditioners after thermocycling. The only exception was observed for MPP, which showed an increase in SBS after thermocycling (p < 0.05). Differences in SBS were noted among the groups with conditioners (p < 0.05), and no significant difference in SBS was noted between TL and OP groups, which showed the highest values among all within the P group. No significant difference was noted between MPP and S. Debonded surfaces showed adhesive failures predominantly located between metal surface and opaque resin.

CONCLUSIONS

The OP and TL conditioners and surface sandblasting with 250 microm Al(2)O(3) promoted the highest SBS between resin and the Ni-Cr metal surface.

Effects of alumina-blasting and adhesive primers on bonding between resin luting agent and zirconia ceramics

This study evaluated the effect of alumina-blasting and three commercial adhesive primers on the shear bond strength of a dual-cured resin luting agent to zirconia ceramics. Two different-sized zirconia ceramic specimens were treated with or without alumina-blasting and then treated with one of three adhesive primers. Subsequently, specimens were cemented together with Linkmax HV (GC). Half of the specimens were stored in water at 37 degrees C for 24 hours and the other half thermocycled 10,000 times before shear bond strength testing. For groups treated with either alumina-blasting or primer, shear bond strength significantly decreased after thermal cycling. For groups treated with both alumina-blasting and one of the three primers, there were no significant differences in shear bond strength before and after thermal cycling (p<0.05). It was thus concluded that the application of each of the three adhesive primers following alumina-blasting was effective for strong bonding of resin luting agent to zirconia ceramics.

Influence of metal cleaning methods on the resin bond strength to NiCr alloy

OBJECTIVES

The purpose of this laboratory study was to evaluate the influence of different metal cleaning methods on the bond strength of various resin bonding systems and its durability to a NiCr alloy. The hypothesis was that the resin bond strength and its durability is related to the cleaning method and to the bonding system used.

METHODS

Plexiglas tubes filled with composite resin were bonded to NiCr disks using three different bonding systems: tribochemical silica-coating and silanization of the alloy, acrylization of the alloy, or bonding with a phosphate monomer containing composite resin. For each bonding system, three cleaning methods were used after the last air abrasion step: cleaning with a stiff brush, ultrasonic cleaning in alcohol or in a neutral detergent. For each combination 20 samples were bonded. Subgroups of 10 bonded samples were tested for tensile strength following storage for either 3 or 150 days. In addition, the 150-day samples were thermal cycled 37,500 times. The statistical analyses were made by ANOVA, followed by multiple pair-wise comparison of the groups using Scheffe and t-tests with Bonferroni-Holm correction.

RESULTS

The mean tensile bond strengths ranged from 34.8 to 49.2 MPa after 3 days and from 2.1 to 43.1 MPa after 150 days. Acrylization of the alloy did not provide durable bond strength to NiCr alloy over storage time. Cleaning the alloy surface with alcohol provided statistically significant higher bond strength than the other cleaning methods after 3 days.

SIGNIFICANCE

Alloy cleaning methods after air abrasion have a significant influence on the resin bond strength.

Shear bond strength of aesthetic materials bonded to Ni-Cr alloy

OBJECTIVES

This study was undertaken to evaluate the shear bond strength of four materials used as aesthetic material bonded to Ni-Cr alloy.

METHODS

Sixty-eight alloy discs were prepared and divided equally into four groups, and received four treatments for veneering: conventional feldspathic porcelain (Noritake EX-3) and three light-cured prosthodontic composite resins (Artglass, Solidex and Targis). The aesthetic materials were applied after metal structure conditioning in accordance with the manufacturers' recommendations. The specimens were stored in distilled water at 37 degrees C for 7 days. A universal testing machine was used to measure the shear bond strength of the specimens at a cross head speed of 0.5 mm/min. Fractured specimens were examined by using both optical and scanning electron microscope.

RESULTS

The analysis of variance and Tukey's test showed that the strongest mean shear bond was obtained with Noritake EX-3 (mean shear bond strength 42.90+/-7.82 MPa). For composites, the highest mean shear bond strength was observed for Targis (12.30+/-1.57 MPa); followed by Solidex (11.94+/-1.04 MPa) and Artglass (10.04+/-0.75 MPa). Optical analysis of the fractured surfaces indicated that for Targis and Noritake EX-3 all failures were a mixture of both cohesive and adhesive patterns. As for Artglass and Solidex, the fractures were mainly adhesive in nature.

CONCLUSIONS

The Solidex system was equivalent to the Targis system in bond strength and exhibited greater strength than the Artglass system. The porcelain fused-to-metal showed considerably higher shear bond strength than the three metal-resin bonding techniques.

Resistance of core materials against torsional forces on differently conditioned titanium posts

STATEMENT OF THE PROBLEM

The separation of core materials from titanium posts, which have a low modulus of elasticity, has been identified as a problem in restorative dentistry.

PURPOSE

This study evaluated the resistance to torsional forces of various core materials adapted to differently conditioned titanium posts.

MATERIAL AND METHODS

Seven hundred and twenty specimens were tested consisting of: 6 core materials and 5 surface conditioning techniques for 2 kinds of opaquers with 10 specimens in each group (6 x 5 x 2 x 10=600) plus 6 core materials and 2 opaquers were tested and considered as control groups on nonconditioned titanium posts, each group containing 10 specimens (6 x 2 x 10=120). The custom-made pure titanium posts were conditioned with the following products: Silicoater Classical, Silicoater MD, Rocatec, Kevloc, and Siloc surface-conditioning systems. Subsequently, 6 core materials with different compositions (Durafill, Adaptic, Coradent, Ti-Core, Hytac Aplitip, and Photac-Fil Aplitip) were applied to titanium posts that were previously coated with 2 types of light-polymerized opaquers, either Artglass or Dentacolor. Sixty air-abraded titanium posts (250 microm, 30 seconds) were used as controls for each core material. Following thermocycling (5 degrees -55 degrees C, 30 seconds, 5,000 cycles), maximum torsional forces were determined with an electronic torque movement key. Data were statistically analyzed by 1-way analysis of variance followed by 2-way analysis of variance (P<.05).

RESULTS

Significantly higher mean torsional forces were observed with respect to Siloc (20.4 Newton decimeter [dNm]), Silicoater Classical (18.6 dNm), Silicoater MD (18.2 dNm), and Rocatec (17.0 dNm) systems compared with the mean for the untreated control group (14.6 dNm) (P<.001). The Kevloc system (10.4 dNm) demonstrated no significant difference compared with the control group (P>.001). The Kevloc system in combination with the Artglass opaquer and Photac-Fil Aplitip (0.00 dNm) core material showed no resistance against torsional forces. Significant differences were observed between hybrid core materials and microfilled composite, compomer, or resin-modified glass ionomer core materials (P<.001).

CONCLUSION

Within the limitations of this study, the resistance to torsional forces for the core materials on titanium posts increased with the use of chemical surface-conditioning techniques and varied in accordance with the opaquer type. Type of core material also significantly influenced the resistance after thermocycling.

Shear bond strength of resin composite veneering material to gold alloy with varying metal surface preparations

STATEMENT OF PROBLEM

Although adequate surface preparation is indispensable to achieve a consistent and durable bond between resin composite materials and the metal substructures of veneered restorations, information on the bonding performance of current metal adhesive systems is limited.

PURPOSE

The purpose of this study was to evaluate the surface preparation effects of 4 metal conditioners and 1 adhesive system on bonding between a prosthetic resin composite veneering material and a gold casting alloy.

MATERIAL AND METHODS

Four primers containing sulfur derivative monomer and designed for conditioning noble metal alloys (Alloy Primer, Infis Opaque Primer, Metal Primer II, and Metaltite) and a surface modification technique (Siloc) were assessed. Cast disk specimens made of gold alloy (Pontor LFC) were either primed with 1 of the 4 primers or treated with the Siloc system and bonded with a light-activated prosthetic resin composite material (New Metacolor Infis). Control specimens were also prepared without the use of a bonding agent. Shear bond strengths were determined before and after thermocycling (20,000 cycles) for evaluation of bond durability.

RESULTS

All of the primed and Siloc-treated groups showed improved 24-hour shear bond strengths compared with the control group. After thermocycling, the groups either primed with the Metaltite conditioner or treated with the Siloc system exhibited the highest mean shear bond strengths.

CONCLUSION

The Metaltite conditioner and Siloc system each represent a useful method for improving the bond between the gold alloy and resin composite material tested.

Effectiveness of metal surface treatments in controlling microleakage of the acrylic resin-metal framework interface

STATEMENT OF PROBLEM

Microleakage at the junction between the metal alloy and acrylic resin in a removable partial denture may result in discoloration, fluid percolation, and acrylic resin deterioration. The junction between a metal alloy and acrylic resin is an area of clinical concern. Failure of a removable partial denture may be linked to this interface. Enhancing resistance to microleakage at this interface may improve the long-term union between the 2 materials.

PURPOSE

This investigation was designed to determine the effects of various metal surface treatment protocols on microleakage and bond strength between the metal alloy and acrylic resin used in the fabrication of a removable partial denture.

MATERIAL AND METHODS

Ninety-six nickel-chromium-beryllium alloy specimens were randomly divided into 8 groups. After adaptation of baseplate wax, each specimen was invested. Subsequent to wax removal, each specimen was divided into a control half and an experimental half. Air abrasion, tinplating/oxidation, and silanation were evaluated individually and in all combinations. Heat-polymerized acrylic resin was processed against all specimens before storage in distilled water at 37 degrees C for 72 hours. Each specimen then was thermocycled in distilled water (3000 cycles) before immersion in sodium fluorescein dye for 24 hours. Counting grids that exhibited dye penetration under ultraviolet light exposure allowed assessment of microleakage.

RESULTS

Air abrasion resulted in a significant decrease in microleakage when used individually and in all combinations (P<0.05). All experimental combinations that did not involve air abrasion demonstrated no significant reduction in measured microleakage between the experimental and control sides. Tukey's pair-wise comparison of the difference in the mean number of squares exhibiting microleakage between the control and treated sites for each experimental group revealed a significant difference, based on the involvement of air abrasion. Groups involving air abrasion did not differ significantly from each other (P<0.05). In addition, no significant difference was detected between groups not involving air abrasion (P<0.05).

CONCLUSION

Air abrasion, alone and in combination with tinplating/oxidation and with silanation, resulted in a significant reduction in microleakage between the metal alloy and acrylic resin.

Dental materials: 1995 literature review

This critical review of the published literature on dental materials for the year 1995 has been compiled by the Dental Materials Panel of the United Kingdom. It continues the series of annual reviews started in 1973 and published in the Journal of Dentistry. Emphasis has been placed upon publications which report upon the materials science or clinical performance of the materials. The review has been divided by accepted materials classifications (fissure sealants, glass polyalkenoate cements, resin composites, dentine bonding, dental amalgam, endodontic materials, casting alloys, investment materials, resin-bonded bridges and ceramo-metallic restorations, all ceramic restorations, denture base and soft lining materials, impression materials, dental implants, orthodontic materials and biomechanics). Three hundred and thirty articles published in 68 titles have been reviewed.

Review of dental materials citations: Part B, July to December 1995

OBJECTIVE

A lag of many months occurs between journal issue publication and updates to electronic databases. The objective of this literature analysis was to identify and categorize all of the dental materials citations in biomedical journals that were published from July 1995 through December 1995.

METHODS

Seventeen primary and 51 secondary journals were searched using their tables of contents to detect and record dental materials publications from July to December of 1995. Those journals that were typically rich in dental materials articles were classified as primary ones. Citations were categorized into 17 topics and divided into subsections. The review excluded case reports, most literature related primarily to dental implants, and most articles on biomedical materials used outside of the field of general dentistry.

RESULTS

The greatest number of citations was related to topics of dentin bonding and resin-based restorative filling materials (composites and glass ionomers). There was no major change in the number of dental materials publications per year reported from 1993 (n = 786) to 1995 (n = 751).

SIGNIFICANCE

This citation list provides a comprehensive resource for use by academicians and researchers to bridge the gap between initial publication and access to electronic searching methods for major databases.