Comparative strength of metal-ceramic and metal-composite bonds after extended thermocycling

The relative strengths of ceramic-to-metal and composite-to-metal bonds were compared after prolonged thermocycling. A total of 104 cast discs were produced from a gold alloy (Pontor LFC). A ceramic material (Duceragold) was fused to 24 discs to assess the strength of the metal-ceramic bond. An indirect composite material (New Metacolor Infis) was bonded to the remaining discs after surface preparation by Rocatec tribochemical coating, tin plating and priming with a phosphate conditioner [10-methacryloyloxydecyl dihydrogen phosphate (MDP), Cesead II], priming with a thione conditioner (V-Primer) or no treatment (unprimed control). Shear bond strengths were determined before and after thermocycling at 20,000 and 100,000 cycles. Pre-thermocycling bond strengths were ranked in the order: metal-ceramic (40.5 MPa); Rocatec treatment (33.1 MPa) and tin plating-MDP (31.0 MPa); V-Primer (20.9 MPa); and control (11.9 MPa). The bond strengths of the first three groups were not significantly different after 20,000 thermocycles, whereas those of the V-Primer and control groups were significantly reduced. After extended thermocycling (100,000 cycles) the metal-ceramic group had the highest mean shear bond strength (28.5 MPa; P < 0.05), followed by the Rocatec (23.9 MPa) and tin plating-MDP (22.1 MPa) groups. The metal-ceramic bond was the most durable, although its strength was reduced by 29.6% after extended thermocycling. On the basis of these results, we recommend the Rocatec and tin plating-MDP systems for composite-to-metal bonding. Metal-ceramic bonding, however, is superior to metal-composite bonding within the limitation of the current experiment.

Adhesive bonding of composite material to cast titanium with varying surface preparations

The purpose of the present study was to evaluate the surface preparation effects of eight metal conditioners and an adhesive system on bonding between a prosthodontic composite material and cast titanium. Eight primers designed for conditioning base metal alloys (Acryl Bond, All-Bond 2 Primer B, Alloy Primer, Cesead II Opaque Primer, Eye Sight Opaque Primer, Metafast Bonding Liner, Metal Primer II, and MR Bond) as well as a surface modification technique (Siloc) were assessed. Disk specimens cast from titanium (T-Alloy H) were either primed with one of the eight primers or treated with the Siloc system, and then bonded with a light-activated composite material (Artglass). Bond durability was evaluated by thermocycling (4 and 60 degrees C, 1 min each, 20, 000 cycles). After thermocycling, two groups either primed with the Cesead II Opaque Primer material or treated with the Siloc system exhibited significantly greater bond strength (20.0 and 19.0 MPa) than the other groups (0.2-12.6 MPa, P < 0.05). These two systems are considered to be useful for improving bonding between the titanium and the composite material tested.

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.

Effect of noble metal conditioners on bonding between prosthetic composite material and silver-palladium-copper-gold alloy

STATEMENT OF PROBLEM

Mechanical retentive devices and the application of complicated surface preparation have been indispensable for bonding composite material to the metal substructure of restorations.

PURPOSE

This study evaluated the priming effects of 4 metal conditioners on bonding between a prosthetic veneering material and a silver-palladium-based casting alloy.

MATERIAL AND METHODS

Four primers designed for conditioning noble metal alloys (Alloy Primer, Metaltite, Metal Primer II, and V-Primer) were assessed (all materials contain organic sulfur compounds). Cast disk specimens made of silver-palladium-copper-gold alloy (Castwell M.C.12) were primed with 1 of the 4 primers, and bonded with a light-activated prosthetic composite material (Axis). Shear testing was performed before and after thermocycling for evaluation of bond durability.

RESULTS

All primed groups showed improved 24-hour bond strengths compared with the unprimed group. After thermocycling, 3 groups primed with the Metal Primer II, Alloy Primer, and Metaltite agents exhibited the highest bond strength.

CONCLUSION

Use of 1-liquid metal conditioners containing sulfur compounds was a simple and useful method for improving bonding between the alloy and the composite material tested.

Primary malignant melanoma of the male urethra

We report a case of primary malignant melanoma of the male urethra, increasing the total number of reported cases to 31. The experience with our case suggests that urinary cytology is a diagnostic method for malignant melanoma and essential in the preoperative diagnosis of this disease.

[A case of bilateral testicular germ cell tumors of different cell types with maturation in the metastatic region]

A case of bilateral testicular germ cell tumors of different cell types and maturation in the metastatic region is described. A 42-year-old man with bilateral testicular swelling visited our clinic. Bilateral high orchiectomy was performed. Subsequent histological examination revealed seminoma and embryonal carcinoma in the right testis and seminoma and mature teratoma in the left. Then bilateral retroperitoneal lymphadenectomy was performed and 7 metastatic regions were found in the para-aortic lymph nodes. One of these revealed histopathologically a mature teratoma containing cartilage constituents. After the operation, multiple drug treatment with Cis-DDP, vinblastine and pepleomycin was started. The patient has been in complete remission for about 1.5 year. In addition, we reviewed the literature about bilateral testicular germ cell tumors and maturation in the metastatic region.

Spontaneous maturation in the metastatic region of a bilateral testicular germ cell tumor

A case of bilateral testicular germ cell tumor of different cell types was found to have a mature teratoma in the metastatic region. Histology of the right testis revealed seminoma and embryonal carcinoma while the left testis revealed seminoma and mature teratoma. A mature teratoma, containing cartilage components, was also found in the right para-aortic lymph node. The findings of the case are described and the literature on cases with maturation in the metastatic region are reviewed.

[Compared studies of antimicrobial agents against E. coli, Klebsiella, Citrobacter and Proteus isolated from urinary tract infections]

In vitro activities of antibacterial agents against E. coli, Klebsiella, Citrobacter and Proteus which were isolated from patients urinary tract infections at 8 hospitals in Japan, were investigated by agar dilution method from July to October in 1979. The summarized results are as follows. 1. Among oral antibacterial agents, MPC and PPA have showed potent antibacterial activities against E. coli and Klebsiella. Among parenteral antibiotics, CTM was the most active against E. coli and Klebsiella. However, ABPC-resistant E. coli and Klebsiella have appeared to occupy about 40% and 96% of bacteria isolated from urinary tract infections, respectively. 2. In vitro activities of antibacterial agents against Proteus and Citrobacter showed not so potent. 3. Causative organisms in female patients with simple urinary tract infections were mainly E. coli and Klebsiella. 4. Among oral antibacterial agents, PPA have shown similar antimicrobial activities against E. coli isolated from simple and complicated urinary tract infections. ABPC and MPC have been influenced in some degree by these factors. However, parenteral antibiotics are not influenced by these factors. On the other hand, in vitro activities of antibacterial agents against Klebsiella isolated from simple and complicated urinary tract infections were similar.