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Biomedical subjects

J Rendell

Publications and source records attributed to J Rendell.

10 recordsLinked to original sources
PubMed1996

The effect of a computer-generated patient-held medical record summary and/or a written personal health record on patients' attitudes, knowledge and behaviour concerning health promotion.

OBJECTIVE: The aim of the study was to examine the effect of a computer-generated patient-held medical record summary (CHR) and/or a written personal health record (PHR) on patients' attitudes, knowledge and behaviour concerning health promotion. METHOD: It was conducted in five general practices in Oxfordshire. Patients aged 25-65 years in each practice were randomly assigned to receive either a CHR plus PHR, CHR only, PHR only, or no personal record. Patients were recruited by mail (one practice) or opportunistically by nurses (four practices). Health checks were carried out using the randomly assigned record, which the patient retained. Attitudes to patient-held records, and pre- and post-intervention knowledge and behaviour concerning health promotion, were assessed using questionnaires. Only those who responded to 'before' and 'after' questionnaires were included in the analysis. RESULTS: A sample of 261 patients was obtained from mail recruitment and 103 from opportunistic nurse recruitment. Patients receiving a CHR as part of mail recruitment were significantly more likely to attend for a health check (P = 0.016). Those receiving both PHR and CHR were more likely to keep (P = 0.014) and use (P = 0.029) the record. Those receiving PHR as part of the package improved their knowledge of health promotion and became more aware of and more likely to change their life-style (P = 0.022). CONCLUSIONS: The effectiveness of a computer-generated patient-held health summary and an explanatory booklet together is greater than either separately in changing patients' knowledge attitudes and behaviour concerning health promotion.

Adult↗
PubMed1995

Retention and stability of the maxillary denture during function.

The objectives of this study were to provide a quantitative account of the extent to which the maxillary complete denture moves during function (chewing, swallowing, and speech production) and to determine whether differences in movement occur as a function of denture fit. A total of 24 patients were studied, 12 with poorly fitting dentures and 12 with well-fitting dentures. Denture movements were measured with a Myotronics kinesiograph that tracked the movements of a small magnet attached to the inferior surface of the denture. Results indicated that denture movement was greatest for the two chewing activities; varied extensively from individual to individual; and that there were no statistically significant overall movement effects as a function of fit. It was concluded that all maxillary dentures are subject to movements in all directions, but that the degree of movement is related more to the individual denture wearer than it is to the fit of the denture.

Aged↗
PubMed1994

Characteristics of muscle fatigue in patients with myofascial pain-dysfunction syndrome.

The purpose of this study was to compare the properties of muscle fatigue in the masseter and temporalis muscles of normal individuals and those with myofascial pain-dysfunction syndrome (MPD). The MPD muscle is presumed to have different characteristics of fatigue than its healthy counterpart; these characteristics can be quantitated using standard electromyogram (EMG) signal-processing techniques. A total of 18 patients diagnosed as having MPD comprised the experimental group and 15 adults with no history or present symptoms of temporomandibular joint pain and dysfunction served as controls. Surface EMG recordings were made for both the masseter and anterior temporalis muscles while the subject held an incisal bite force level of 10 N for as long as possible. The EMG data were transferred to a microcomputer where the power-density spectrum of the signals were calculated for 2-s samples at 10-s intervals. The mean power frequency (MPF) and power (root mean square, r.m.s.) of the signals were calculated from the power-density spectra. Results showed: (1) the endurance times were significantly shorter for the MPD patients; (2) the masseter was not active in three of 17 MPD patients; (3) decreases in MPF over time were significantly greater for the MPD patients than normal subjects; (4) increases in r.m.s. power were significantly greater over time for the MPD patients; (5) bandwidths of the power-density spectra were similar for the two groups. The implication of these results is the MPD muscle is not in a state of constant fatigue, as is currently believed, but rather demonstrates accelerated fatigue.

Adolescent↗
PubMed1994

Estimating human incisal bite forces from the electromyogram/bite-force function.

This study used the electromyogram (EMG)/force-function curve as a means of estimating functional bite forces. Surface EMG recordings were made for the masseter and anterior temporalis muscles bilaterally in ten adults while incisal bite forces were measured using a force transducer embedded in custom-made hydroplastic bite blocks. Measurements were made for mouth openings of 15 and 30 mm. Each subject was first instructed to develop a maximum level of bite force, and then to develop bite-force levels that corresponded to decreasing percentages of his or her maximum, from 90 to 10%, in 10% decrements. After the force measurements had been made, each subject was instructed to incise various food substances. The power-density spectrum and r.m.s. power level were calculated for each sample. Maximum bite-force levels varied considerably among the 10 subjects, ranging from a minimum of 2.5 kg to a maximum of 40 kg. For the subjects as a whole, estimated bite forces for the different types of food ranged from 3.0 to 5.5 kg. This range was independent of the subjects' maximum bite-force levels. Thus, bite forces exerted to incise different foods probably depend more on the food than on the individual's bite capabilities. There was variability within this range, although, as expected, bite forces were least for chocolate and greatest for apple and toffee.

Adult↗
PubMed1994

Effect of denture adhesive on the retention and stability of maxillary dentures.

This study used quantitative methods to measure the effects of a denture adhesive on the retention and stability of the maxillary denture. Denture movements were measured on 20 patients during standardized chewing, swallowing, and speaking activities, first with no adhesive, and then at 0, 2, 4, 6, and 8 hours after application of an over-the-counter cream adhesive. The major findings were that the denture adhesive produced a statistically significant improvement in the retention and stability of the maxillary denture during the various chewing, swallowing, and speaking activities, for up to 8 hours; there were no statistically significant differences in improvement between a poorly fitting and well-fitting denture; and patients were able to produce significantly greater levels of incisal bite force with the use of the adhesive.

Adhesives↗
PubMed1993

Use of sodium hyaluronate in treating temporomandibular joint disorders: a randomized, double-blind, placebo-controlled clinical trial.

This study assessed the efficacy of high-molecular-weight sodium hyaluronate as a treatment for certain intracapsular temporomandibular joint (TMJ) disorders. One hundred twenty-one patients were studied at three test sites using a randomized, double-blind, placebo-controlled experimental design. Patients were selected on the basis of 1) confirmed diagnosis of either degenerative joint disease (DJD), reducing displaced disc (DDR), or nonreducing displaced disc (DDN); 2) nonresponsiveness to nonsurgical therapies; and 3) severe dysfunction as established by the Helkimo indices (HI), visual analog scales (VASs), and physical measurements of joint movement and joint noise (arthrophonometry [APM]). Subjects received a unilateral upper joint space injection of either 1) 1% sodium hyaluronate in physiologic saline (MedChem Products, Woburn, MA) or 2) USP physiologic saline. Clinical evaluations were performed using HI, VAS, and APM at weekly intervals for the first month and then at monthly intervals up to 6 months postinjection. Statistical analyses for both categorical and continuous variables were performed for each diagnostic category at each examination interval. For DJD, no difference in outcome was seen between treatment groups. For DDN, significant between-group differences were seen through 1 month; however, beyond this time point, the number of DDN patients was insufficient to draw meaningful conclusions concerning efficacy. For DDR, statistically significant within-group and between-group improvement in all three measures (HI, VAS, APM) was seen for the hyaluronate group compared to the saline group throughout the 6-month test period. At the month-2 and month-3 examination intervals, twice as many patients treated with hyaluronate (90%) showed improvement compared to patients given placebo. Further, only 3% of patients with DDR who were treated with hyaluronate relapsed compared with 31% of patients with DDR given placebo.

Adult↗
PubMed1993

Effect of jaw opening on masticatory muscle EMG-force characteristics.

This study was designed to evaluate the way in which changes in vertical jaw opening affected the relative contributions of various masticatory muscles to bite force production. EMG activity was recorded simultaneously from the masseter, and anterior, middle, and posterior temporalis muscles, during controlled isometric biting at different force levels and vertical jaw openings. EMG-force characteristics were compared between muscles and bite openings. All but the posterior temporalis muscle displayed significant increases in muscle activity with increased bite force production; the masseter muscle demonstrated the largest activity increments. Statistically significant changes in muscle function due to jaw opening were demonstrated only for the masseter muscle, though similar trends were observed for the anterior and middle temporalis muscles. Minimum increases in muscle activity associated with increases in bite force occurred between 9 and 11 mm of opening, measured at the first molar, for all three muscle groups. The results of this study suggest that changes in masticatory muscle length resulting from vertical jaw opening cause alterations in muscle contractile properties, but the relative contributions of various masticatory muscles toward bite force production may also be affected by biomechanical factors and neural control adaptations.

Biomechanical Phenomena↗
PubMed1992

Masticatory muscle fatigue: endurance times and spectral changes in the electromyogram during the production of sustained bite forces.

The purpose of this experiment was to determine if the characteristics of fatigue observed in the limb muscle system are also evident in the muscles of mastication, specifically, the masseter and temporalis. Surface electrodes were placed bilaterally over the masseter and temporalis muscles of 10 adults. Each subject was instructed to maintain maximal and six levels of submaximal incisal bite forces for as long as possible. The power density spectrum of the electromyographic signals for each muscle was calculated at the onset and failure of the task. The decrease in endurance time with an increase in bite force followed a pattern similar to that in limb muscles, and each muscle was characterized by a consistent reduction in the mean power frequency of the power density spectrum and a variable change in r.m.s. power. The variability of changes in r.m.s. power (which is inconsistent with changes found in the limb muscles) was explained in terms of either changes in motor-unit firing rate or the muscle's relative contribution to the generation of bite force. The analyses also demonstrated a curvilinear relationship between bite force and r.m.s. power, but no relationship between bite force and the mean power frequency of the power density spectrum.

Adult↗
PubMed1991

Electromyographic-force characteristics in the assessment of oral function.

The purpose of this investigation was to examine the utility of EMG-force characteristics as reliable and valid parameters by which to assess oral function. Masseter-muscle activity was recorded during controlled isometric biting exercises performed at various bite openings and force levels on two separate occasions. Measured muscle-activity levels, as well as the EMG-force characteristics of slope and y-intercept, were compared between bite openings and experimental trials. Sensitivity, assessed as the ability to detect statistically significant differences in muscle function due to changes in muscle length, was found to be acceptable for all measurements, except the y-intercept parameter, and during production of minimal forces. Reproducibility, evaluated as the correspondence between values recorded at different experimental sessions, was best for the EMG-force parameter of slope and during production of higher forces. The results from this study support the following conclusions: (1) Substantial variations in muscle function exist between individuals; (2) acceptable reliability and sensitivity of quantitative EMG values can be achieved, especially at higher muscle-activity levels, by rigidly controlling and quantifying functional activities during experimental trials; (3) the slope of an EMG-force curve is a reproducible, quantitative, and functionally sensitive measurement for assessment of muscle function; and (4) the EMG-force y-intercept is not a reliable quantity by which muscle-function characteristics may be studied.

Adult↗