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Biomedical subjects

I R Matthew

Publications and source records attributed to I R Matthew.

13 recordsLinked to original sources
PubMed2000

Release of metal in vivo from stressed and nonstressed maxillofacial fracture plates and screws.

OBJECTIVES: To analyze the release of metal into the adjacent tissues from stressed and nonstressed titanium and stainless steel miniplates and screws. STUDY DESIGN: Two miniplates were inserted into the cranial vaults of 12 beagle dogs while they were under general endotracheal anesthesia. One miniplate was shaped to fit the curvature of the skull (control). Another miniplate, made of the same material, was bent in a curve until the midpoint was raised 3 mm above the ends. Screws were inserted and tightened until the plate conformed to the skull curvature, creating stresses in the system. Four animals (2 each, having titanium or stainless steel plates and screws) were killed after 4, 12, and 24 weeks. Metallosis of adjacent soft tissues was assessed qualitatively. Miniplates and screws were removed, and adjacent soft tissue and bone was excised. Titanium, iron, chromium, nickel, and aluminum levels were assayed by ultraviolet/visible light and atomic absorption spectrophotometry. Nonparametric statistical methods were used for data analysis. RESULTS: There was no clear relationship between pigmentation of soft tissue adjacent to the miniplates and screws and the concentrations of metal present. The data did not demonstrate any consistent differences in the concentrations of metallic elements next to stressed and nonstressed (control) miniplates and screws of either material. CONCLUSION: Stresses arising through poor contouring of miniplates do not appear to influence the extent of release of metal into the adjacent tissues.

Aluminum↗
PubMed2000

Dose response and safety of cizolirtine citrate (E-4018) in patients with pain following extraction of third molars.

The objectives of this study were to determine the dose response and safety of the oral analgesic cizolirtine citrate (E-4018) in patients with postoperative pain after third molar extraction. This was a placebo-controlled, double-blind, randomised, parallel-group study. Doses of E-4018 were 50 mg, 100 mg, or 150 mg. The primary outcome measure of efficacy was patient assessment of pain severity, determined from serial visual analogue scales (VAS) over a four-hour investigation period. Other efficacy measures included the number of patients taking escape analgesic and the time before it was taken, and an overall assessment of pain relief on a four-point categorical scale. There was no significant difference between any of the E-4018 treatment groups and placebo in terms of the AUC for VAS pain scores over time. The percentages of patients who took paracetamol within five hours of their dose were 100%, 95%, 78% and 82% for the placebo, 50 mg, 100 mg and 150 mg E-4018 groups, respectively. The time to first use of paracetamol was significantly different for the 100 mg and 150 mg E-4018 groups compared to placebo. There were 17 adverse events, of which five were possibly related to the study medication (one in the placebo group and four in the 150 mg E-4018 group). We conclude that there was a dose-related trend in the percentage of patients requiring paracetamol within five hours of their study medication, and in the percentage of patients that recorded the treatment as providing good or excellent treatment of pain. There was, however, no firm evidence of a dose-related analgesic effect over the dose range of Cizolirtine chosen for this study. E-4018 was well tolerated in all patients.

Adult↗
PubMed1999

Policy of consultant oral and maxillofacial surgeons towards removal of miniplate components after jaw fracture fixation: pilot study.

A pilot study was undertaken to find out the policy of the 23 consultant oral and maxillofacial surgeons in the West Midlands towards removal of miniplates after jaw fractures had healed. All 23 replied. Two consultants did not use miniplates; the other 21 respondents used titanium systems, and two also used a stainless steel system. None of the 21 respondents routinely removed all miniplates. The estimated total of miniplates removed after the fracture had healed ranged between 5% and 40% (mode 5%). The main indications for removal were wound infection or dehiscence, before construction of a prosthesis, patients' concern about permanent retention of an implant, and thermal conductivity. We conclude that miniplates and screws are removed mainly to treat symptoms caused by the implants.

Attitude of Health Personnel↗
PubMed1999

Metallic fragments on the surface of miniplates and screws before insertion.

Particulate metal fragments have been identified histologically within the tissues adjacent to miniplates and screws after they have been removed. These were thought to have been caused by corrosion and degradation of the metal. However, the particles may have originated from rough edges or from protuberances left on the metal surface after cutting and machining during manufacture, and subsequently become detached. This study was undertaken to analyse the incidence and distribution of metal fragments on the surface of miniplates and screws before use. Fifteen miniplates and 60 screws were examined by stereomicroscopy and scanning electron microscopy. Rough metal edges or protuberances were identified on over half the samples, mostly in the countersink area of screw holes on the mini-plates. Fragments were detected within some of the cruciform screw heads and on some screw threads. We conclude that metal protuberances are present on the surface of mini-plate components when they are received from the manufacturer. There is a risk that the fragments might be detached and deposited into the tissues during insertion.

Alloys↗
PubMed1998

The comparative efficacy of aceclofenac and ibuprofen in postoperative pain after third molar surgery.

The aim of the present placebo-controlled, double-blind study was to evaluate the comparative efficacy of single doses of aceclofenac 150 mg and ibuprofen 400 mg in 217 patients with postoperative pain after third molar surgery. Outcome of primary efficacy was judged by overall assessment of the area under the curve (AUC) of graphs for pain intensity (AUC pain) pain relief (AUC relief), both measured from serial visual analogue scales over a 6 h investigation period. Other measures of efficacy included the rate of pain reduction in the first hour, the number of patients who took 'escape' analgesics and the time before they did, and an overall assessment of pain relief score on a five-point categorical scale. Ibuprofen 400 mg was significantly superior to placebo for pain relief (P < 0.01), degree of pain reduction in the first hour (P = 0.005), and the number of patients who required escape analgesia (P < 0.001), and the time before they did (P < 0.001). The outcome for patients treated with aceclofenac 150 mg was not significantly different from that of patients treated with placebo (P > 0.05). A single dose of ibuprofen 400 mg provided significant pain relief in the early postoperative period after third molar surgery, whereas a single dose of aceclofenac 150 mg was not effective in the management of postoperative pain after this operation.

Adult↗
PubMed1998

Ultrastructural analysis of metal particles released from stainless steel and titanium miniplate components in an animal model.

PURPOSE: Low-vacuum scanning electron microscopy (Ivac SEM) was used to characterize the appearance of metal particles released from stressed and unstressed Champy miniplates placed in dogs and to study the relationship of the debris to the surrounding tissues. MATERIALS AND METHODS: Under general endotracheal anesthesia, two Champy miniplates (titanium or stainless steel) were placed on the frontal bone in an animal model. One miniplate was bent to fit the curvature of the frontal bone (unstressed) and another miniplate of the same material was bent in a curve until the midpoint was raised 3 mm above the ends. The latter miniplate adapted to the skull curvature under tension during screw insertion (stressed). The miniplates and surrounding tissues were retrieved after intervals of 4, 12, and 24 weeks. Decalcified sections were prepared and examined by light microscopy and Ivac SEM. RESULTS: Under Ivac SEM examination, the titanium particles had a smooth, polygonal outline. Stainless steel particles were typically spherical, with numerous small projections on the surface. Most particles were 1 to 10 microns in diameter. The tissue response to the particles was variable; some particles were covered by fibrous connective tissue or enclosed by bone, and others were intracellular. CONCLUSIONS: The metal particles released from stressed or unstressed Champy miniplates were similar, and this was related to their source of origin and duration within the tissues. The tissue response to the particles appeared to depend on their location.

Anesthesia, Endotracheal↗
PubMed1998

Development and evaluation of a computer-aided learning package for minor oral surgery teaching.

'Aspects of Minor Oral Surgery' is a highly interactive software program that was commissioned by the Department of Health, England, as part of the continuing education opportunities of general dental practitioners. The content of the program is also suited to the education of senior clinical dental students. The beta (pre-release) version was evaluated by 67 general dental practitioners, who completed a questionnaire on aspects of the program's functionality. Responses on its usefulness as an educational tool were 78% positive and 4% negative. In comparing the program to other educational media on the same subject, 77% felt it was better than video, 69% said it was better than textbooks, and 80% preferred it to journals. Its main strengths were judged to be the high level of interactivity, the ease of navigation and use, and the quiz section. The quality of the images of surgical procedures displayed in the slide shows was judged to be a weakness, and this problem was addressed in preparing the final version. Ten UK academic and four health service senior oral surgeons were also asked to give feedback on the program's content, and these points were also incorporated in the final text. More than 1,600 copies of the program have been taken up by general dental practitioners so far. The program may be downloaded for evaluation via the internet.

Adult↗
PubMed1998

Forces transmitted through a laminated mouthguard material with a Sorbothane insert.

Sorbothane is a visco-elastic polyurethane that has been used in sports and orthopaedic applications because of its shock-absorbing properties. The aim of this laboratory study was to evaluate the effect of an intermediate layer of Sorbothane on the peak force transmitted through two thermoplastic ethylene vinyl acetate (EVA) sheets as used in the construction of a custom-made sports mouthguard. The EVA sheets were tested at room temperature after thermal lamination under pressure, either without (control) or with a Sorbothane intermediate layer of 1.1 or 2.65 mm thickness. A piezo-electric transducer was used to measure the peak force transmitted through each sample from a free-falling steel ram. The peak force recorded was significantly less for laminated EVA samples with a Sorbothane intermediate layer than for controls of comparable thickness. We conclude that a Sorbothane intermediate layer between heat-cured laminated EVA sheets, as used in the fabrication of a custom-made sports mouthguard, may dissipate significantly the force of impact resulting from a blow to the teeth and jaws.

Analysis of Variance↗
PubMed1996

In vivo surface analysis of titanium and stainless steel miniplates and screws.

This study was undertaken to characterize the surfaces of Champy titanium and stainless steel miniplates and screws that had been used to stabilize fractures of the mandible in an animal model. Miniplates and screws were retrieved at 4, 12, and 24 weeks after surgery. Low-vacuum scanning electron microscopy (SEM) of autoclaved unused (control) and test miniplates from the same production batches was undertaken. Energy-dispersive X-ray (EDX) analysis was used to identify compositional variations of the miniplate surface, and Vickers hardness testing was performed. At autopsy, clinical healing of all fractures was noted. SEM analysis indicated no perceptible difference in the surface characteristics of the miniplates at all time intervals. Aluminium and silicon deposits were identified by EDX analysis over the flat surfaces. There was extensive damage to some screw heads. It is concluded that there were no significant changes in the surface characteristics of miniplates retrieved up to 24 weeks after implantation in comparison with controls. Damage to the screws during insertion due to softness of the materials may render their removal difficult. There was no evidence to support the routine removal of titanium or stainless steel miniplates because of surface corrosion up to 6 months after implantation.

Analysis of Variance↗
PubMed1995

Subperiosteal behaviour of alginate and cellulose wound dressing materials.

A histological comparison was undertaken of the tissue response to a new sodium calcium alginate material (Kaltostat) and an oxidized regenerated cellulose wound dressing (Surgicel) when implanted between bone and periosteum in the jaws at intervals of up to 24 wk. Both biomaterials caused a foreign body reaction, persisting up to 12 wk after surgery. New bone formation occurred along the surface of the mandible in some specimens, but was not apparently related to the implants. It was concluded that the implantation of Kaltostat or Surgicel between bone and periosteum in the jaws caused a delay in wound healing, and had no effect on bone induction.

Alginates↗
PubMed1994

Alginate fiber dressing for oral mucosal wounds.

The aim of this study was to evaluate the effect on hemostasis and wound healing of a proprietary alginate fiber dressing when applied to a wound of the buccal mucosa of approximately 2 mm depth. The study showed a significant reduction in the number of residual bleeding points in shallow wounds when the alginate fiber dressing was applied for 5 minutes as compared with the use of non-alginate-impregnated surgical gauze. There was no significant difference in the rate of epithelial repair of the test and control sites nor in the area of the resulting mucosal scar. In addition, there was no significant difference in the numbers of tissue components in the submucosa. It is concluded that the alginate fiber dressing material evaluated in this study may be effective as a hemostatic mucosal dressing in shallow wounds, but it does not accelerate mucosal wound healing.

Alginates↗
PubMed1993

Tissue response to a haemostatic alginate wound dressing in tooth extraction sockets.

Kaltostat is a new haemostatic wound dressing composed of non-woven sodium calcium alginate fibres, and was originally developed to cover exposed wounds of the skin. A histopathological study was undertaken to determine the tissue response to Kaltostat in healing tooth sockets, to obtain a comparison with oxidised regenerated cellulose (Surgicel). Tooth sockets filled with blood clot acted as controls. The results showed that both biomaterials delayed wound healing in the early phase (1-4 weeks), giving rise to foreign body reactions. At 12 weeks there was little difference between the control sockets and the sockets containing the test materials, although remnants of retained dressing materials were identified. Healing of the tooth sockets was complete at 24 weeks.

Alginates↗