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Biomedical subjects

M R Heath

Publications and source records attributed to M R Heath.

At least 19 recordsLinked to original sources
PubMed1995

Automated optical scanning for rapid sizing of chewed food particles in masticatory tests.

Analysis of the reduction in sizes of particles after chewing has been a standard method for assessing masticatory efficiency for over 40 years, but the sizing of particles with sieves is very time consuming. A rapid simple method of measuring chewed almond particle sizes by an optical scanning method has been developed and is described. The aim of this study is to validate the accuracy, repeatability and speed of the application of an optical scanning system in measuring chewed particles. To determine the accuracy, paper circles were measured and compared with the travelling microscope measurements. The effect of orientation of the images were assessed by measuring three irregular shaped pieces of paper and three different sized pieces of chewed almonds. Measurements were taken singly at 18 degrees increments from 0-180 degrees orientations with each piece of paper. To assess the repeatability of measuring chewed particles, the particles from a single masticated almond washed with water and absolute alcohol were spread, separated and measured by the optical scanning system. The samples were then remeasured 10 times. The reproducibility of the method was investigated using three repeated masticatory tests for each subject in a group of 13 young dentate subjects. The speed of spreading the particles and of measurement was assessed. The absolute error range for a mean area of 31 mm2 was 2.85% to 7.32% with a mean of 3.86%. The relative accuracy of measurement was higher for larger particles but in no case was the standard deviation > 0.4 mm2.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1994

The effect of age on the recognition thresholds of three sweeteners: sucrose, saccharin and aspartame.

It is believed that people's sensitivity to taste declines with age but the evidence is inconclusive. This study was designed to test the hypothesis that taste recognition thresholds (TRTs) for sweetness are higher in older than in younger individuals, using groups of 16 younger subjects (18-30) and 16 older subjects (60-85). Three test substances were used: sucrose, aspartame and saccharin. A questionnaire recorded variables which might have affected TRTs, but data failed to show any trend that might have biased the principle variate-age. There was a significant alteration with age of recognition thresholds, at least for sucrose and saccharin. The differences between the groups for the three sweeteners were due to the fact that all the very sensitive subjects were young. None of the older subjects had particularly poor discrimination: all but one had TRTs within the range of younger subjects. Although there are age-related taste changes, they are much less dramatic than commonly occurs with other senses, such as sight and hearing. The findings of this study have implications for institutional catering and the dietary management of older people using non-sugar sweeteners.

Adolescent↗
PubMed1992

A multicenter study of overdentures supported by Brånemark implants.

Nine clinical centers participated in a prospective study of overdentures supported by Brånemark implants in the maxilla or mandible. The study initially comprised 133 patients provided with 117 implants placed in the maxilla and 393 implants placed in the mandible. The preliminary results indicate a success rate in the mandible comparable with the reports on fixed prostheses. Conversely, overdenture treatment in the maxilla seems to be less favorable than previous reports of fixed restorations. The differences between the fixed and the present overdentures in the maxilla were mainly based on differences in patient selection and bone quality. A total of 32 implants was mobile and removed and another 29 implants were lost to follow-up because of patient dropout up to the first annual checkup after denture placement. A higher implant failure rate occurred in the maxilla. Mucosal reactions were also more unfavorable around implants placed in the maxilla.

Adult↗
PubMed1991

Swallow thresholds using dentures made on different types of articulator.

The purpose of this study was to determine whether edentate subjects achieved different performance when using dentures constructed on different articulators. A cross-over experimental design was employed to evaluate these swallow thresholds using complete dentures constructed on the hinge and free plane articulators. Seven subjects completed the study. Swallow threshold tests were performed 3 months after the insertion of dentures. The overall particle size distribution achieved with the dentures constructed on free plane articulators was significantly better at the end of the 3-month period (P less than 0.01 to P less than 0.0001), but significantly more strokes were used to achieve this success rate (P less than 0.04). A questionnaire revealed that the subjects had a preference for the denture constructed on the free plane articulator. It is concluded that patients performed better with dentures constructed on the free plane articulator.

Adult↗
PubMed1991

Salivary levels of mutans streptococci, lactobacilli, yeasts, and root caries prevalence in non-institutionalized elderly dental patients.

Root caries prevalence was recorded for a consecutive sample of dental patients (n = 146), aged over 55 yr and with at least 12 natural teeth. The mean root DFS score of the males (n = 49) was 6.34 +/- 4.55 and for the females (n = 97) 3.76 +/- 3.31 (P less than 0.001). The salivary levels of mutans streptococci, lactobacilli, and yeasts were determined in addition to salivary flow rate and buffering capacity. Subjects with greater than 1 root DFS had significantly higher salivary levels of mutans streptococci, lactobacilli, and yeasts. They also had fewer teeth and more exposed root surfaces. In step-wise multivariate analyses the factors significantly related to the root DFS score were the number of exposed root surfaces, number of teeth, sex and salivary yeast levels (R2 = 0.41). In the multivariate analyses salivary levels of mutans streptococci were not significantly related to any clinical measurement of root caries experience due to the greater strength of association between the root DFS score and salivary levels of yeasts. Subjects prescribed medicines with a reported xerostomic effect had significantly fewer active root lesions than those not prescribed such medicines and salivary levels of all microorganisms studied were significantly elevated in subjects prescribed medications containing sucrose.

Aged↗
PubMed1991

Case report: the management of severe tooth wear with palatal resin bonded cast restorations combined with removable partial dentures.

The restoration of advanced tooth wear can present considerable problems. Conventional fixed prosthodontic treatment can be destructive to the already compromised dental tissues, time consuming and therefore costly. With recent advances in resin bonded technology, this may now be considered an option for definitive treatment in such cases. This case illustrates the use of palatal resin retained cast metal veneers. These veneers restored the worn palatal surfaces of the anterior maxillary teeth, protected them from further wear and controlled thermal sensitivity. They also provided support for a conventional maxillary partial denture.

Aged↗
PubMed1990

Root caries in older people attending a general dental practice in East Sussex.

With increasing numbers of older people retaining their natural dentitions, dentists are becoming increasingly aware of the problem of dental caries occurring on exposed root surfaces--root caries. This study reports the prevalence of root caries in a selected older population, living in the community and attending a general dental practice in Bexhill, East Sussex. A total of 146 non-institutionalised people, aged at least 55 years with at least 12 teeth, were examined. Most of the subjects (88.4%) had evidence of root caries, males and denture wearers having more lesions than females and non-denture wearers, respectively. Active coronal caries was present in only 11.6% of the subjects, whereas active (soft or leathery) root caries lesions were present in 31.5% of the subjects. The teeth and surfaces most commonly affected by root caries were found to be similar to those seen in previous epidemiological surveys. The majority of active root caries lesions were within 1 mm of the gingival margin, while inactive lesions tended to be greater than or equal to 1 mm from the gingival margin. Colour of root caries lesions was not diagnostic of caries activity. A more detailed method of recording root caries lesions is also described.

Aged↗
PubMed1990

Associations between salivary levels of mutans streptococci, lactobacilli, yeasts and black-pigmented Bacteroides spp. and dental variables in elderly dental patients.

Multivariate step-wise regression analyses demonstrated that in a population of 146 elderly dental patients (mean age 69.8 yr) the salivary level of mutans streptococci was unrelated to the root DFS score, unlike the levels of lactobacilli and yeasts. Mutans streptococci were related to the wearing of partial dentures and the number of snacks eaten per day, while salivary lactobacillus levels were also related to the number of snacks eaten per day and to denture wearing, and negatively related to saliva buffering. Salivary yeast levels were also related to the wearing of partial dentures and the number of snacks eaten per day, and negatively related to salivary neuraminidase activity. The R2 values ranged from 0.21 to 0.28. Salivary level of black-pigmented Bacteroides spp. were related to maximum CPITN score, mean bleeding index and salivary trypsin-like activity (R2 was 0.08).

Aged↗
PubMed1982

The effect of maximum biting force and bone loss upon masticatory function and dietary selection of the elderly.

Simple methods are described for measuring masticatory effectiveness--the percentage of sugar chewed out of chewing gum in 20 strokes--and the height of residual mandibular bone using callipers. Both are objective methods, they are acceptable to the elderly, appropriate for denture wearers and practicable for use in domiciliary surveys. Using these and other methods, the masticatory effectiveness of housebound pensioners is shown to relate to maximum biting force, denture quality, remaining mandibular bone and dietary selection. However, opinions on the difficulty of mastication are completely unrelated to any of these measures. The level of compensation for inadequate mastication is indicated by the percentage of difficult foods eaten by geriatric hospital inpatients: there was complete overlap of percentages in those endentulous patients using dentures and those without dentures. Presumably many of these patients had adapted to swallowing very poorly chewed food. The contrasts shown between hospital inpatients and old people still at home indicate the progressive consequences of physical and neurological deterioration.

Adult↗
PubMed1980

Measurement of cephalometric radiographs: methods of analyzing data on a regional basis and improving reading efficiency.

Because of the complexity of craniofacial structures, it is valuable to analyze morphology and posture of one structure relative to more than one origin or region. Coordinate geometry can provide analysis of data from radiographs on a regional basis very efficiently because th data need not be remeasured relative to second or subsequent regions. This application is illustrated by analysis of lingual posture relative to the maxilla and relative to the mandible. The method, which provides efficient comparative measurement of two or more films of one patient, involves neither tracing nor marking on films. The measurements are recorded independently from each film; they can thus be free from bias and replicated for improved accuracy. The technical repeatability is analyzed.

Cephalometry↗
PubMed1980

Electropalatography: thermo-formed pseudopalates and the use of three-dimensional display.

Electropalatography provides a method of recording contact of the tongue against the palate; this has valuable potential in linguistics, phonetics, speech therapy, oral physiology and dentistry. The application of the technique has been limited by the time required to produce a plate (pseudopalate) carrying electrodes for each person studied. The bulk of an acrylic plate also imposes some interference with speech. A simple, relatively fast, method of producing very thin plates is described. The use of models to provide three-dimensional display is illustrated and the value of slow speed play-back of data is discussed.

Data Display↗
PubMed1980

Photo-electric recording of orofacial posture and movement providing linear, digital output.

A method for kinematic recording is evaluated. Its application for measuring both cranial and mandibular movement is described. the method provides accurate, linear, digital, co-ordinate measurement of up to four points with minimal interference with movement of the structures being examined. The field of measurement can be controlled optically; resolution being +/- 0.1% of the field width.

Humans↗