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At least 127 records · Page 7Linked to original sources
PubMed2006

The polymethyl methacrylate cervical cage for treatment of cervical disk disease Part III. Biomechanical properties.

BACKGROUND: In a previous article, we used the PMMA cervical cage in the treatment of single-level cervical disk disease and the preliminary clinical results were satisfactory. However, the mechanical properties of the PMMA cage were not clear. Therefore, we designed a comparative in vitro biomechanical study to determine the mechanical properties of the PMMA cage. METHODS: The PMMA cervical cage and the Solis PEEK cervical cage were compressed in a materials testing machine to determine the mechanical properties. RESULTS: The compressive yield strength of the PMMA cage (7030 +/- 637 N) was less than that of the Solis polymer cervical cage (8100 +/- 572 N). The ultimate compressive strength of the PMMA cage (8160 +/- 724 N) was less than that of the Solis cage (9100 +/- 634 N). The stiffness of the PMMA cervical cage (8106 +/- 817 N/mm) was greater than that of the Solis cage (6486 +/- 530 N/mm). The elastic modulus of the PMMA cage (623 +/- 57 MPa) was greater than that of the Solis cage (510 +/- 42 MPa). The elongation of PMMA cage (43.5 +/- 5.7%) was larger than that of the Solis cage (36.1 +/- 4.3%). CONCLUSIONS: Although the compressive yield strength and ultimate compressive strength of the PMMA cervical cage were less than those of the Solis polymer cage, the mechanical properties are better than those of the cervical vertebral body. The PMMA cage is strong and safe for use as a spacer for cervical interbody fusion. Compared with other cage materials, the PMMA cage has many advantages and no obvious failings at present. However, the PMMA cervical cage warrants further long-term clinical study.

Biomechanical Phenomena↗
PubMed2001

Effect of polyaramid fiber reinforcement on the strength of 3 denture base polymethyl methacrylate resins.

PURPOSE: The interactive effects of synthetic polyaramid reinforcement fibers on the transverse strength of intact and repaired heat-polymerized denture base acrylic resins were investigated. MATERIALS AND METHODS: Three polymethylmethacrylate (PMMA) polymers were tested: Acron MC (GC International Corp, Scottsdale, AZ), Lucitone 199 (Dentsply International Inc, York, PA), and Microlon (The Hygienic Corp, Akron, OH). With each polymer, there were 2 controls and 4 experimental groups (n = 9 per group). The treatment groups were intact heat-polymerized PMMA control, PMMA with unreinforced repair, PMMA with polyaramid reinforced repair, intact polyaramid reinforced heat-polymerized PMMA control, polyaramid reinforced PMMA with unreinforced repair, and polyaramid reinforced PMMA with polyaramid reinforced repair. The transverse fracture strengths of the samples were measured with a 3-point bending test on a Zwick Universal Testing Machine (Zwick of America, Inc, East Windsor, CT). RESULTS: The highest mean strength at fracture was recorded with intact polyaramid reinforced heat-polymerized PMMA controls for all resins. Analysis of variance showed significant differences in transverse strength (p < .05) by experimental group, by material, and by interaction of group and material. Tukey HSD (honestly significant difference) Multiple Comparisons Test (alpha = 0.05) showed that intact polyaramid reinforced heat-polymerized PMMA controls were significantly stronger than intact heat-polymerized PMMA controls and all the other treatment groups. Use of polyaramid reinforcement in repair of unreinforced PMMA or polyaramid reinforced PMMA did not result in significantly increased transverse strength. CONCLUSIONS: Polyaramid reinforcement significantly increased the transverse strength of intact heat-polymerized PMMA. Polyaramid fibers did not significantly increase strength to reinforce PMMA repairs.

Acrylic Resins↗
PubMed2000

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.

Analysis of Variance↗
PubMed1982

Comparison of bond strengths of polymethyl methacrylate and alpha cyanoacrylate.

A method of fabricating similar methyl methacrylate cylinders was used to produce specimens to test the bond strength of alpha cyanoacrylate and autopolymerizing methyl methacrylate. Each group was tested immediately and after storage in 37 degrees C water bath for 90 days. Statistical analysis supported the finding that the autopolymerizing methyl methacrylate produced a better bond even without undercuts or mechanical retention.

Chemical Phenomena↗
PubMed1993

Complement activation by polymethyl methacrylate minimized by end-point heparin attachment.

After intraocular lens implantation, despite good clinical results, many cataract patients develop a chronic uveitis, caused by an inflammatory response to the implant. One way to improve the biocompatibility of the intraocular lens is to modify the surface by end-point heparin attachment. This study shows that complement activation caused by poly(methyl methacrylate) can be diminished by end-point heparin attachment, as demonstrated by a significant reduction in the generation of C3a and fluid phase terminal complement complexes. It suggests that assessment of complement activation is a good indicator of the biocompatibility of intraocular lenses.

Biocompatible Materials↗
PubMed1998

The influence of substratum topography on bacterial adhesion to polymethyl methacrylate.

The effect of substratum roughness on the adhesion of Pseudomonas aeruginosa and Staphylococcus epidermidis was investigated using PMMA. A small increase in Ra values (0.04-1.24 microm) resulted in a significant increase (P<0.05) in bacterial attachment. Subsequent increases in surface roughness (Ra=1.86-7.89 microm) resulted in a decrease in adhesion, although adhesion was still higher than to the smooth surface. When the PMMA surfaces were coated with protein (bovine serum albumin), no difference (P<0.05) could be determined in the amount of protein adsorbed, irrespective of surface topography. However, the influence of the underlying topography on adhesion was still evident. Substratum topography is an important parameter affecting bacterial adhesion to surfaces.

Journal Article↗
PubMed1992

Increased resistance of bacteria after adherence to polymethyl methacrylate. An in vitro study.

The pathobiology of total joint prosthesis infection was investigated in vitro. Discs of polymethylmethacrylate (PMMA) were exposed to a suspension containing cells of 10(8) per mL Staphylococcus epidermidis E-46. After 12 hours, exposed discs were rinsed with phosphate-buffered saline and placed in brain heart infusion broth containing antibiotics (2.5 mg per mL of Cephaloridine). After gentle shaking for 24 hours at 37 degrees C, the bacteria on the PMMA surface were detached and washed with phosphate-buffered saline to remove the antibiotics. Compared with the free bacteria which were detached from the PMMA by sonication immediately after exposure to the antibiotic solution, those allowed to remain adhered to the PMMA surface were more resistant to antibiotics. Scanning electron microscopy showed accumulation of bacteria surrounded by slime on PMMA discs exposed for 12 hours. Our results indicate that resistance of bacteria to antibiotics is increased after adherence to the biomaterial and formation of a slime layer.

Bacterial Adhesion↗