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Biomedical subjects

N B Pitts

Publications and source records attributed to N B Pitts.

At least 145 records · Page 8Linked to original sources
PubMed1986

An image analysis system for the determination of tooth dimensions from study casts: comparison with manual measurements of mesio-distal diameter.

A first comparison of an image analysis method with classical hand measurement was made using the mesio-distal diameter data derived by the simplest image analysis method, the jawview mode. Fifty casts of male Hong Kong Chinese dental students, mean age 20.4 years, were examined by both methods. The two techniques gave comparable overall results, the correlation coefficients generally being greater than 0.9. A combination of the buccal and occlusal image analysis views gave the best correlation with hand measurement with a comparable variability for different tooth types. For certain teeth, particularly posteriors, reproducibility was better using hand measurement. Optimal weighting of the data from these two different image analysis views can give an "estimated hand measurement" value. Further development of the method to deal with differing orientations of teeth is possible.

Adult↗
PubMed1985

Score system for behaviour of radiologically diagnosed approximal carious lesions.

The evolution of systems which monitor changes in the severity of approximal carious lesions diagnosed from serial bitewing radiographs is reviewed. These systems derive a 'score' for each individual lesion based upon the extent of its progression. A new lesion behaviour score system is described which, unlike its predecessors, allows both lesion regression and data from partially overlapped but readable surfaces to contribute to scores. It employs scoring codes from a previously proposed standardized grading system which is compatible with WHO recommendations for grading clinical caries. The score system is designed to be used as a computer program capable of running on a variety of readily available microcomputers; this allows the incorporation of a flexible range of additional options which use the standard data files to calculate scores according to differing conventions. These accommodate variations in: the threshold at which restorative intervention is practiced, the treatment of reversals of caries diagnosis, the threshold of caries diagnosis and the way in which partially overlapped surfaces are scored. These options allow the system to be configured to suit the local needs of different investigations and workers, and also permit the study of the effects of these various methodologies.

Dental Caries↗
PubMed1985

Reproducibility of computer-aided image-analysis-derived estimates of the depth and area of radiolucencies in approximal enamel.

In vivo studies of caries progression from serial bite-wing radiographs require the reproducible detection and measurement of approximal radiolucencies in enamel; the aim of this study was to evaluate the reproducibility of a new computer-aided image analysis method. Three series of radiographs depicting natural caries lesions were employed: films of 11-12-year-old (Hounslow) schoolchildren, dental students from Hong Kong (HKDS), and extracted Hong Kong teeth (EXT). Each surface was "searched" three times, resulting in data from 450, 600, and 180 searches, respectively. Lesion detection was consistent for all but two of the 1230 searches. Average values for the standard error of the mean (SEM) of triple determinations of depth % were between 2.0 and 3.5%, while the mean SEM for area was from 0.03 to 0.04 mm2. Average test/re-test correlations ranged from 0.963 to 0.871 for depth and from 0.963 to 0.884 for area, while average reliability coefficients ranged from 0.937 to 0.821 for depth and 0.963 to 0.886 for area. There was a significant difference (P less than 0.001) between the reproducibility of the two clinical series, with measurements of the Hounslow lesions being more consistent. When compared with the reproducibility of attempts to grade radiolucency size visually, the image analysis method appears to offer considerable advantages, in that consistent estimates of radiolucency size are now possible. This method may facilitate more sensitive assessments of the behavior of lesions over time than has hitherto been possible.

Adult↗
PubMed1984

Detection and measurement of approximal radiolucencies by computer-aided image analysis.

Serial standardized bitewing radiography permits monitoring of the development of approximal carious lesions. A quantitative method using image-analysis techniques was developed. Only certain types of hardware proved capable of processing this complex image adequately. A computer-aided, software-driven, TV-based system incorporating an image memory, recursive filtration, and 256 gray-level resolution, which can both detect and measure approximal enamel radiolucencies produced by natural carious lesions, has been developed. The radiolucent boundary is delineated, displayed, and plotted to scale. For the first time, objective values for depth, area, width, perimeter, and "degree of radiolucency" can be automatically derived. Currently the system is seen as a tool in caries research; in the future such systems may have wider applications.

Computers↗
PubMed1984

Systems for grading approximal carious lesions and overlaps diagnosed from bitewing radiographs. Proposals for future standardization.

The diagnosis of dental caries from bitewing radiographs has become an important and integral part of many clinical caries trials, particularly in longitudinal studies. Although many seemingly similar systems for grading the degrees of approximal lesions have been used, the diagnostic criteria employed often differ in a number of significant areas. A variety of different conventions have evolved for the treatment of: 1) overlapping surfaces, 2) lesions in the region of the ADJ, 3) subdivision of the radiographic enamel cap and 4) score transitions and caries progression systems. Direct intertrial comparisons may be invalidated by the use of incompatible grading systems. Whilst one rigid grading system will not be suitable for all clinical trials, the use of the appropriate scoring codes and criteria from a standard system may greatly facilitate the comparison and interpretation of results. A comprehensive standard system for the grading and scoring of radiographic diagnoses (compatible with the existing WHO recommendations for the grading of clinically diagnosed lesions) is proposed.

DMF Index↗
PubMed1983

Monitoring of caries progression in permanent and primary posterior approximal enamel by bitewing radiography.

The work which has monitored caries progression in posterior approximal enamel surfaces by reference to the size of radiolucency seen on bitewing radiographs is reviewed. There are wide variations in the degree of standardisation achieved, in the composition of the study groups and in the duration of the studies. There is a paucity of information relating to adults, the elderly, groups with low caries prevalence, and fluoridated communities. The results indicate that for the majority approximal caries progresses slowly, and large numbers of lesions remain unchanged for long periods. The available results are compared using the mathematical model of a negative exponential. The 'mean' time during which a lesion remains radiographically confined to the enamel is of the order of 3-4 yr, although in caries active individuals much shorter times are reported. Some clinical implications are suggested and the need for further research using comparable methods is stressed.

Adolescent↗
PubMed1983

Terminology.

Explore the source record for details and available documents.

Dental Caries↗
PubMedDate not supplied

Temporary elective tooth separation as a diagnostic aid in general dental practice.

This study examined the feasibility, acceptability and potential diagnostic value of using a 'blanket' technique for placing elastomeric separators as a diagnostic aid in a general practice situation. Five practices were visited and 211 children between 5 and 15 years were examined. All 211 children accepted the 'clinical without separators' examination, 37 children were unwilling to have the radiographic examination and 12 of the 146 children who required separators refused or removed them. The use of the technique as a routine aid was acceptable to the host practitioners, the parents, most of the patients and to the clinician conducting the study. The method was shown to be valuable in revealing additional approximal lesions. A total of 703 lesions were disclosed by the 'clinical with separators' method, compared with 479 diagnosed by routine clinical examination alone. As many of the additional lesions were at the precavitation stage, this information could be used to target those patients with special needs for preventive care. While the larger dentinal lesions revealed by temporary elective tooth separation were confirmed by bitewing radiographs, many of the small precavitation lesions were not. The results showed, however, that bitewing radiographs were still an important diagnostic aid, especially in the deciduous dentition. Elastomeric separators may have a role as a diagnostic aid in conjunction with bitewings, rather than as a replacement for them.

Adolescent↗
PubMedDate not supplied

A randomised controlled trial of the caries-preventive efficacy of a chlorhexidine-containing varnish in high-caries-risk adolescents.

A professionally applied two-stage chlorhexidine varnish, Chlorzoin((R)), was developed to achieve sustained release and minimise the problems of staining and bad taste associated with chlorhexidine mouthrinses. The primary aim of this randomised controlled clinical trial was to assess the efficacy of Chlorzoin in reducing the caries increment in high-caries-risk adolescents. Secondary aims included investigating the effect of compliance upon caries increment, the effect of Chlorzoin upon salivary mutans streptococci levels and assessing the benefit of individual dental health advice by dental auxiliaries in a community setting. 1,240 children, initially aged 11-13 years, assessed to be at high caries risk were recruited into the trial. The trial design involved four arms: an observational group, a control group, an active (Chlorzoin) varnish group and a placebo varnish group. All subjects were examined annually by a calibrated examiner who was blind to the group allocation. Three-year caries increments were calculated using clinical, clinical and fibre-optic transillumination, and clinical and bitewing data sets. The results indicated that the use of Chlorzoin had an initial effect on mutans streptococci levels but that no long-term reduction in caries increment or mutans streptococci infection could be detected. One reason for this lack of efficacy may have been the regimen of reduced frequency of varnish applications after the initial period. Children who followed the protocol and, therefore, were seen regularly by dental auxiliaries had a lower caries increment than those who did not. This finding was independent of varnish allocation. In summary, under this regimen, Chlorzoin has been found to be effective in decreasing salivary mutans streptococci but ineffective as a caries-preventive agent in high-risk Scottish children when applied pragmatically in a community setting.

Adolescent↗