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Biomedical subjects

N J McDonald

Publications and source records attributed to N J McDonald.

At least 19 recordsLinked to original sources
PubMed1997

Development of a direct weighting procedure for quality of life domains.

The Schedule for the Evaluation of Individual Quality of Life allows individuals to nominate the domains they consider most important to their quality of life and to use their own value system when describing the functional status and relative importance of those domains. The weights for domain importance are derived through a procedure called judgement analysis. As judgement analysis is impractical for individuals with cognitive impairment and in many clinical situations, a shorter, direct weighting procedure has been developed. To test the new procedure, 40 healthy individuals completed both direct and judgement analysis weightings, at t1 and 7-10 days later (t2). After a further 7-10 days (t3), they were asked to identify the weight profiles they had previously produced using each method. The weights produced by the two methods differed on average by 7.8 points at t1 and 7.2 points at t2. The direct weights changed on average by 4.5 points from t1 to t2, while the judgement analysis weights changed by 8.4 points. At t2, 55% of individuals were able to identify the direct weights they had previously produced. The new procedure demonstrates stability and validity but is not interchangeable with judgement analysis. The most appropriate ways of using and interpreting both procedures are discussed.

Activities of Daily Living↗
PubMed1996

Comparison of radiographic and electronic working lengths.

The purpose of this study was to compare the ability of radiographic and electronic methods to determine reliably the location of the apical constriction. The working length of root canals in human cadaver teeth was determined by positioning an endodontic file at the apical termination point as indicated by an apex locator. These same teeth were radiographed at various angles with the file in place. The radiographs were evaluated by five examiners to determine a radiographic termination point for each canal. Teeth were extracted and examined histologically to determine the ideal termination point. The deviations of the two experimental termination points from the ideal termination point were compared. The mean of the absolute value of the deviations from the apical constriction for the apex locator was significantly less (p < 0.05) than that for the radiographic method. Thus, the method using the apex locator was slightly more reliable.

Dental Pulp Cavity↗
PubMed1995

The treatment of postanaesthetic shivering: a double blind comparison between alfentanil and pethidine.

It has been postulated that pethidine may mediate its effects on postanaesthetic shivering (PAS) via kappa-opioid receptors. However, clinical evidence indicates that alfentanil, a pure mu-agonist, may also have beneficial effects on PAS. In order to assess whether opioid effects on PAS are effected via kappa receptors, fifty-one patients were randomised to receive alfentanil 250 micrograms (n = 18), pethidine 25 mg (n = 18) or placebo (n = 15) on a double-blind basis for the treatment of established postanaesthesia shivering (PAS). Both drugs proved significantly better in treating PAS than placebo (P < 0.005). Following treatment, blood pressure fell and oxygen saturation increased in patients in the two treatment groups when compared with the control group (P < 0.05). There was a highly significant incidence of reshivering in the alfentanil treated group (P < 0.005). In conclusion, the high incidence of reshivering indicates that alfentanil is unlikely to supercede pethidine in the treatment of PAS, but its initial success rate implies that pethidine's anti-shivering effect is unlikely to be mediated via kappa-opioid receptors.

Adolescent↗
PubMed1994

Individual quality of life in the healthy elderly.

Quality of life research with the elderly has usually focused on the impact of decline in function, and used a pre-determined model of quality of life in old age. The Schedule for the Evaluation of Individual Quality of Life (SEIQoL) allows individuals to nominate, weigh and assess those domains of greatest relevance to their quality of life. The SEIQoL was administered to 56 healthy elderly community residents at baseline and 12 months later. Quality of life levels were significantly higher at baseline (t = -2.04; p = 0.04) than that of a previously studied sample of healthy adults below 65 years of age, and did not change significantly over the study period. The domains nominated by both samples as relevant to their quality of life differed notably. Health status was not correlated with the perceived importance of health at baseline, and showed only a low correlation (r = 0.27) at 12 months. The weight placed on health did not increase over the study period despite a significant decline in health status. The value of allowing the individual to define personal quality of life values in a research context is explored.

Adult↗
PubMed1993

Cytotoxicity of retrofill materials.

Dentin bonding agents reduce microleakage and enhance marginal adaption of composite resin restorations. These characteristics are advantages for their use as an endodontic retrofilling material. Because these materials will be in direct contact with vital tissues, their cytotoxic potential must be evaluated before clinical use. It was the purpose of this study to evaluate the cell cytotoxicity of amalgam, Caulk Universal Bond, Gluma, 35% HEMA, Morita Clearfil, Scotchbond 2, Super EBA, Tenure, and Tenure 5-4. VERO cells were grown in RPMI-1640 medium and cell monolayers were prepared by incubating 15 ml of the cell suspension in 60-mm culture dishes at 37 degrees C in 5% CO2. Twelve milliliters of a medium-agarose mixture containing 1% neutral red vital stain were overlayed onto the cell layer and allowed to solidify. The materials were directly exposed to the agarose overlays by inverting 6.0-mm diameter polypropylene capsules containing the cured and liquid sample materials either immediately (0 time) or after placement in phosphate-buffered saline with 1% gentamicin for 7, 15, or 30 days. Cytotoxicity was determined by measuring the zone of killed cells around the sample 24 h after placement on the agarose. Cytotoxicity was determined by measuring the zones of cell inhibition at 24 h and at 7, 15, and 30 days. Initially, all of the materials were found to be cytotoxic, except amalgam and the Tenure components. The dentin bonding primers showed a mean zone of inhibition of 13.2 mm and the cleansers a 40.0-mm zone. Amalgam demonstrated increasing cytotoxicity: 0.0 mm at 24 h to 12.0 mm at 30 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid Etching, Dental↗
PubMed1993

Effect of sterilization on contaminated sponges.

Sponges are routinely used as a storage medium for endodontic files during clinical practice; however, very little research has been done to determine the effectiveness of sterilization procedures for these contaminated sponges. The purpose of this in vitro study was to determine the efficacy of chemical vapor sterilizers (chemiclaves), steam pressure sterilizers (autoclaves), and dry heat sterilizers on laboratory contaminated sponges. Four different types of sponges were used in this study: a black, relatively nonporous sponge; a red, semiporous stationary sponge; a blue, endodontic sponge, and a yellow, common household sponge. Natural sponges were eliminated from the study, because their large pore size made them unsuitable as a storage medium for endodontic instruments. The sponges were divided into three groups: chemiclave, autoclave, and dry heat. Five samples of each sponge type were impregnated with biological indicating strips containing spores of Bacillus stearothermophilus. Each sponge was subjected to 25 cycles of sterilization. The spore strip indicator was inserted into the sponges at 1, 5, 10, 15, 20, and 25 cycles. The spore strip was cultivated in trypticase soy broth medium solution at 55 +/- 1 degree C for 7 days. At 7 days the culture vials were read for turbidity; its presence indicating a positive culture. The samples that were subjected to chemiclaving demonstrated positive cultures of 0.00%, 0.00%, and 30.00% and those to autoclaving 3.33%, 0.00%, and 0.00% positive cultures for the black, red, and blue sponge types, respectively. None of the sponges survived dry heat sterilization. The O-Cell-O sponges become unusable when subjected to all of the sterilization methods used in this study.

Equipment Contamination↗
PubMed1992

The electronic determination of working length.

Electronic digital imaging systems provide the clinician with the ability to manipulate, enhance, and store radiographic images for immediate recall. Apex locators are a useful adjunct to endodontic therapy. It is important to understand that they do not replace radiographs completely in treatment. Radiographs still provide the only means by which the clinician can gain an overall visual image of the tooth being treated. It is important to visualize the crown and root anatomy; the relationship of the crown to the root; the size, shape, curvature, and location of the roots; and to estimate the tooth length. These data give the clinician a good guide and provide a baseline from which to use an apex locator. Failure to do this will result in errors of measurement due to a lack of basic treatment information. The current types of apex locators available are accurate for determining working length, providing some basic steps are followed carefully for their use. Current generation units have degrees of accuracy that range from 83.0% to 93.4%. They need to have well-charged batteries and to be calibrated correctly before use. Resistance-type apex locators require a reasonably dry canal--a guideline that must be strictly followed. Files must be matched to fit the canal snugly, contact against metallic restorations must be avoided, and good lip contact for the return electrode must be obtained. The impedance-type units require careful calibration before use, careful matching of the coated probe to the canal diameter, and good patient contact with the hand-held return electrode. Care must be taken to ensure that the insulating layer does not wear off the coated probes during use. The frequency-based units are easy to use. They operate in an electroconductive environment and have the advantage of using conventional K-type files. However, the rechargeable battery must be kept fully charged, and their calibration steps must be followed. Fluid filling the tooth to the level of the pulp chamber will cause the units to become overloaded, and careful matching of the file to the size of the canal is necessary. Strict adherence to these simple set-up and calibration procedures and the use of the apex locator in conjunction with high-quality, standardized diagnostic radiographs provide the clinician with an accurate and useful adjunct to endodontic therapy.

Dental Pulp Cavity↗
PubMed1991

Radiographic and electronic diagnostic systems.

Radiography forms the basis for determining the length of tooth in endodontic therapy. Radiographs can be manipulated by digital image processing, which can improve their diagnostic quality as well as enable the images to be stored electronically. Electronic apex locators, when used in conjunction with radiographs and electronic imaging systems, become useful adjuncts in endodontic treatment. They provide the clinician with the ability to accurately determine the length of tooth, thus making apex locators an important component in endodontic therapy.

Dental Pulp Cavity↗
PubMed1990

An evaluation of the Apex Locator Endocater.

The purpose of this study was to relate the relationship of the apical constriction to the anatomical apex and to determine the ability of the Endocater (Hygenic Corp., Akron, OH), using commercially bonded coated probes to locate the position of the apical constriction, in permanent teeth that were intact and had not been subjected to previous endodontic manipulation. Using local anesthesia and rubber dam isolation, conventional access cavities were prepared at ultra high speed with water coolant in teeth treatment planned for extraction. The Endocater was used to determine the working length. The probes were sealed in place with autopolymerizing composite resin and the teeth extracted. The teeth were sectioned buccolingually, and the position of the probe in relation to the anatomical apex and apical constriction was measured with the use of an ocular microscope. In 17.1% of the canals, the probes bound in the coronal portion of the canals and would not reach the apical portion of the root. In those teeth in which the probes reached the apical portion of the root, the Endocater was able to locate the apical constriction within 0.5 mm in 93.4% of the canals.

Dental Pulp Cavity↗
PubMed1990

Comparative in vitro coronal microleakage study of new endodontic restorative materials.

Complete sealing of endodontic access openings between appointments and after completion of therapy is an essential element in achieving endodontic success. Recently, two new products for use as temporary restorative materials, TERM and Dentemp, have become available. The purpose of this study was to compare in vitro the sealing ability of Cavit, Cavit-G, Cavit-W, and IRM-Caps, with TERM, Hard-TERM, and Dentemp. Standard access cavities were prepared in 144 intact extracted human teeth. They were equally and randomly distributed into seven groups, and their access openings were temporized. Specimens were submitted to thermocycling (5 to 55 degrees C) for 7 days and stained with silver nitrate. The teeth were split in half, and the greatest depth of dye penetration at the tooth surface was recorded. TERM exhibited the least leakage, while Hard-TERM demonstrated the greatest leakage, at the tooth-restoration interface.

Dental Cements↗
PubMed1989

Cognitive impairment after neuroleptanalgesia in cataract surgery.

This study was undertaken to evaluate the mental recovery of patients following cataract operations under neuroleptanalgesia. Mental function was assessed by Mini-Mental State (MMS) preoperatively and at 6 and 24 hours postoperatively. Preoperatively, 18.7% of the elderly had cognitive impairment of mental function while none in the younger group had any impairment (P less than 0.02). At six hours postoperatively, 29.7% of the elderly had cognitive impairment compared with 4% of the younger group (P less than 0.01). At 24 hours postoperatively, the percentage of elderly and younger patients with cognitive impairment had returned to preoperative levels. Baseline score and age were found to be significant predictors (P less than 0.004) of the 6-hour score and 24-hour score. In conclusion, cognitive impairment of mental function occurred in patients undergoing cataract operation with retrobulbar block and intravenous sedation at 6 hours postoperatively; MMS has the potential for use as a screening preoperative test for outpatients to identify those at risk for developing cognitive impairment.

Adult↗
PubMed1988

Use of the oxygen cost of breathing as an index of weaning ability from mechanical ventilation.

The oxygen cost of breathing (which is the difference in oxygen consumption measured during controlled ventilation and again during spontaneous ventilation) was measured in 30 patients between the ages of 17 and 96 years at the time of commencement of weaning from mechanical ventilation. There was a significant exponential correlation between the oxygen cost of breathing in ml/m2/min and the oxygen cost of breathing as a percentage of total oxygen consumption during spontaneous ventilation (OCB/VO2SV%) and the duration of weaning in days.

Adolescent↗
PubMed1988

Mood evaluation and outpatient anaesthesia. A comparison between propofol and thiopentone.

Mood state was evaluated in 40 unpremedicated patients who underwent minor gynaecological surgery, before and up to 4 hours after, anaesthesia induced with either propofol 2.5 mg/kg or thiopentone 5 mg/kg. Assessments were made by a self-report technique, the profile of mood states method. The results indicate that mood state was less affected postoperatively in patients induced with propofol than with thiopentone. The overall impression of the investigators was that propofol patients had a definite sense of well-being after anaesthesia.

Adult↗