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At least 91 records · Page 5Linked to original sources
PubMed1995

A review of methods used to reinforce polymethyl methacrylate resin.

Various methods to reinforce acrylic denture base material have been used to repair fractures in complete dentures. Metal wires and plates have been tested as reinforcement of polymethyl methacrylate (PMMA) resin. The contributions of the studies conducted on this biphase composite system are discussed in this review article. The literature has reported that even thin metal wires incorporated into the PMMA matrix increased the transverse strength of the PMMA construction. Metal mesh inserted into PMMA resin had negligible effects on the transverse strength of the restoration. macroscopic retention of the metal strengtheners to the PMMA had only a minor effect on the strength in contrast to microscopic retention, which showed a more marked effect. Chemical bonding between the PMMA and metal reinforcer enhanced the strength of the prosthesis with some exceptions.

Chromium Alloys↗
PubMed1993

Holding power of metallic plates in cancellous bone. An experimental study on rabbits with polymethyl methacrylate as supporting material.

The holding power of a metallic device in cancellous bone was tested in sixteen rabbits (n = 16). The device was fixed with the support of polymethyl methacrylate. The fixation firmness was studied radiologically and by measuring the bonding strength. The mean value of the bonding strength was 485 N (n = 6) at 6 weeks, and 557 N (n = 8) at 12 weeks.

Animals↗
PubMed1995

Use of antibiotic-impregnated polymethyl methacrylate for treatment of an open radial fracture in a horse.

An open, contaminated, comminuted fracture of the radius of a 500-kg adult horse was diagnosed. Antibiotic-impregnated polymethyl methacrylate implants were placed into the fracture site to help eliminate infection from the limb. Later in the course of treatment, lag screws were placed across the fracture to generate compression and healing. The fracture healed, and the horse was released to its owners. The implants were not removed, and only a mild lameness existed 90 days later.

Amikacin↗
PubMed2005

The wettability of polytetrafluoroethylene and polymethyl methacrylate by aqueous solution of two cationic surfactants mixture.

Advancing contact angle (theta) measurements were carried out for aqueous solutions of cetyltrimethylammonium bromide (CTAB) and cetylpyridinium bromide (CPyB) mixtures on polytetrafluoroethylene (PTFE) and polymethyl methacrylate (PMMA). The obtained results indicate that the wettability of PTFE and PMMA by aqueous solutions of CTAB and CPyB mixtures depends on the composition and concentration of the mixture; however, synergism in the wettability does not exist. In the range of low concentrations of aqueous solution mixtures there is a linear dependence between the contact angle and composition of the mixtures, but at a concentration close to CMC a deviation from linear dependence is observed. In contrast to Zisman, there is no linear dependence between costheta and the surface tension of aqueous solution of CTAB and CPyB mixtures, but a linear dependence exists between the adhesional and surface tension, and these lines have a slope -1 and -0.34 for PTFE and PMMA, respectively, which suggests that adsorption of CTAB and CPyB mixtures at water-air and PTFE-water is the same, and the orientation of the CTAB and CPyB molecules at both interfaces in the saturated monolayer should also be the same. Adsorption of these mixtures at water-air interface is considerably higher than at PMMA-water interface, and CTAB and CPyB molecules should be parallelly oriented to PMMA surface in the saturated monolayer. Extrapolation of the straight lines to the points corresponding to the surface tension of aqueous solution, which completely spreads over the PTFE and PMMA surface, gives a critical surface tension of wetting equal to 23.44 and 33.13 mN/m, respectively. The value of 23.44 mN/m is higher than that of the surface tension of PTFE, but the value of 33.13 is lower than that of Lifshitz-van der Waals components of PMMA surface tension. On the basis of the critical surface tension, the surface tension of PTFE and PMMA, the Young equation, and thermodynamic analysis of the adhesion work of aqueous solution of surfactant to polymer surface, it was found that for PTFE and PMMA the changes of the contact angle of aqueous solution of two cationic surfactants mixtures on their surfaces as a function of the solution concentration resulted only from the decrease of the polar component of the solution surface tension.

Journal Article↗
PubMed1991

Effect of Staphylococcus epidermidis on adherence of Pseudomonas aeruginosa and Proteus mirabilis to polymethyl methacrylate (PMMA) and gentamicin-containing PMMA.

The goals of this study were to determine 1) effect of Staphylococcus epidermidis adherence and biofilm production on adherence of the opportunistic pathogens Proteus mirabilis and Pseudomonas aeruginosa to polymethyl methacrylate (PMMA); 2) if the biofilm killed by autoclaving altered adherence of other organisms; 3) if adherence of S. epidermidis to gentamicin-containing PMMA altered adherence of the opportunistic pathogens P. mirabilis and P. aeruginosa to gentamicin-containing PMMA. Results show that biofilms formed by S. epidermidis, whether alive or dead, significantly increased adherence of Pseudomonas. Adherence of Proteus was significantly increased on dead biofilms and increased, but not significantly (p = less than 0.1), on live ones. Greatest adherence seen in the study was to autoclaved biofilms. Significant adherence of Proteus and Pseudomonas was found on gentamicin-containing PMMA specimens, which were preincubated with S. epidermidis for formation on the biofilm. These results indicate that a biofilm is formed on PMMA-gentamicin specimens and this may impair the ability of gentamicin to kill other organisms.

Bacterial Adhesion↗
PubMed1993

Variables affecting silicone-polymethyl methacrylate interfacial bond strengths.

PURPOSE: This study investigated the effects of various polymerization methods and of various types of silane coupling agents on the interfacial bond strengths of Molloplast-B and of two types of heat-processed polymethyl methacrylate (PMMA). MATERIALS AND METHODS: Standardized blocks of PMMA were processed and stored in 100% humidity for 14 days. Silicone of equal dimensions was flasked and processed with premixed and fresh-mixed silane coupling agents interposed. Processing utilized both a typical heated-water system and a dry-heat oven. Following recovery, the specimens were peel-tested at an angle of 180 degrees in an Instron machine. RESULTS: There was no significant difference between the test variables of Lucitone (Dentsply/York Division, York, PA) versus Lucitone 199 (Dentsply/York Division), nor with wet versus dry heat polymerization methods. However, the mean bond strengths for premixed silane improved slightly in a wet polymerization environment. Conversely, fresh-mixed silane's mean bond strength increased slightly with dry-heat polymerization. CONCLUSIONS: The bond strength between a methyl methacrylate denture base and a silicone soft liner varies only slightly when either Lucitone, Lucitone 199, or polymerization in a wet or dry environment is used. Under the conditions of this study, a fresh-mixed silane coupling agent produced a distinctly superior bond strength.

Acrylic Resins↗
PubMed1997

Decentration and tilt of polymethyl methacrylate, silicone, and acrylic soft intraocular lenses.

PURPOSE: The purpose of the study is to investigate the periodic changes regarding the decentration and tilt of the intraocular lens (IOL) and to compare any differences in the decentration and tilt among polymethyl methacrylate (PMMA), silicone, and acrylic soft IOLs. METHODS: A total of 225 cataractous eyes undergoing IOL implant surgery were randomized into 3 groups based on the type of IOL: group A, one-piece PMMA IOL; group B, three-piece silicone IOL; and group C, three-piece acrylic soft IOL. Both the length of the decentration and the degree of the tilt of the IOL were quantitated using the Anterior Eye Segment Analysis System (EAS-1000). All eyes underwent EAS-1000 examinations at 1 week as well as 1, 3, 6, 9, and 12 months after surgery. RESULTS: All IOLs were confirmed to be implanted accurately in the capsular bag after continuous curvilinear capsulorhexis was accomplished. No statistically significant differences were observed regarding the IOL decentration or tilt between the various postoperative periods in any of the three IOL groups. Furthermore, the differences regarding both the IOL decentration and the tilt between the three IOLs were not determined to be statistically significant throughout the observation period. CONCLUSIONS: As long as the IOL was placed properly in the capsular bag after the continuous capsulorhexis, neither the decentration nor the tilt of the IOL showed a significant progression up to 12 months after surgery. Furthermore, both the extent of the decentration and tilt almost were the same among the PMMA, silicone, and acrylic soft IOLs.

Acrylic Resins↗
PubMedDate not supplied

Outcomes and complications associated with ventral screws, pins, and polymethyl methacrylate for atlantoaxial instability in 12 dogs.

Clinical outcomes and complications of a technique used for atlantoaxial stabilization were evaluated in a group of 12 dogs. At surgery, the atlantoaxial joint was realigned and rigidly fixated using cortical bone screws, K-wire, and polymethyl methacrylate. Results in nine dogs were graded as excellent. Results in two dogs were judged as good. One dog was euthanized 17 months after surgery for recurrent cervical pain. Eight dogs had no postoperative complications. The surgical technique described provided an adaptable method for the correction of atlantoaxial instability.

Animals↗
PubMed1995

In vivo effect of pressurization of polymethyl methacrylate bone-cement. Biomechanical and histologic analysis.

Sixteen goats underwent total hip arthroplasty, half with pressurized and half with unpressurized bone-cement. The animals underwent hemiarthroplasty of the contralateral hip immediately prior to sacrifice 6 weeks later. Samples were tested for interface strength and evaluated histologically. Pressurization of polymethyl methylacrylate improves the strength of the bone-cement interface in vivo, as well as in vitro. There is a regional variation in the strength of the bone-cement interface both in vivo and in vitro. The regional variation in the in vivo model is at least in part due to a biologic effect. Membranes forming at the bone-cement interface are usually fibrous and incomplete, allowing direct cement-to-bone contact. Membranes appear to be involved in the remodeling of bone. Polymethyl methacrylate causes significant necrosis of the cortex, with ensuing resorption of the cortical bone. There is a small, statistically insignificant trend toward increased resorption and decreased bone formation with pressurized cement. The amount of necrosis appears to be similar with pressurized and nonpressurized cement. Bone remodels to fill defects in the cement mantle.

Animals↗
PubMed1984

Distribution and elimination of polymethyl methacrylate nanoparticles after peroral administration to rats.

Polymethyl [1-14C]methacrylate nanoparticles were administered orally to bile cannulated rats. Ten to fifteen percent of the administered radioactivity was absorbed and found in the bile and urine. Within 48 h, 94-97% of the absorbed radioactivity had been eliminated from the body. After 8 d, the highest residual radioactivity was found in the bone marrow, fatty renal tissue, stomach, liver, and lymph nodes.

Administration, Oral↗
PubMed1992

Use of an antibiotic impregnated polymethyl methacrylate intramedullary spacer for complicated revision total hip arthroplasty.

Revision total hip arthroplasty is frequently necessary in the presence of significant proximal femoral bone loss, periprosthetic fracture, or infection. In these situations, optimal reconstruction may sometimes warrant the use of special implants, including bone grafts. The emergent presentation of these cases or unexpected findings at the time of surgery can preclude the use of these treatment options. In cases of periprosthetic sepsis, delayed reimplantation may be the most successful approach to eradicate infection. In seven of these complicated revision total hip arthroplasties, the authors used an antibiotic-impregnated intramedullary polymethyl methacrylate spacer with delayed prosthetic reimplantation to allow for the use of these methods. Benefits of this technique include uncompromised radiographic evaluation of the proximal femur for design of a custom implant, if needed, stabilization of the proximal femur facilitating early mobilization of the patient in the case of periprosthetic fracture, and local delivery of antibiotics to the wound in the case of infection. The author's ability to reconstruct these total hip arthroplasties complicated by bone deficiency, fracture, and sepsis, was significantly improved with this use of this technique.

Adult↗
PubMed1996

Use of antimicrobial-impregnated polymethyl methacrylate beads for treatment of chronic, refractory septic arthritis and osteomyelitis of the digit in a bull.

A 6-year-old 895-kg Angus bull was evaluated for a 6-month history of left hind limb lameness that was refractory to antimicrobial treatment. On physical examination, there was soft-tissue swelling associated with the lateral digit. Radiography revealed septic arthritis of the distal interphalangeal joint and osteomyelitis of the distal and middle phalanges. Treatment included debridement and lavage. Bacteriologic culture of debrided tissues yielded aerobic and anaerobic organisms. Antimicrobials were administered parenterally and locally in the form of antimicrobial-impregnated polymethyl methacrylate beads. The limb also was placed in a cast to promote ankylosis. The bull recovered, and the digit was salvaged.

Actinomyces↗