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Biomedical subjects

K Horner

Publications and source records attributed to K Horner.

At least 37 records · Page 2Linked to original sources
PubMed1998

The relationship between mandibular bone mineral density and panoramic radiographic measurements.

OBJECTIVES: To compare densitometric and linear measurements (mandibular cortical thickness, MCT; panoramic mandibular index, PMI) made from dental panoramic tomograms (DPTs) with bone mineral density (BMD) values obtained using dual energy X-ray absorptiometry (DXA) of the mandible and to determine whether measurements from DPTs have validity in predicting BMD. METHODS: Forty edentulous female patients were examined by a DPT incorporating a nickel step wedge and by DXA of the mandible. In each case the equivalent nickel thickness of sites in the mandibular body, MCT and PMI values were calculated and their relationship with DXA measurements assessed. RESULTS: Densitometric measurements of DPTs did not correlate with mandibular BMD. MCT significantly correlated with mandibular BMD (r = 0.50, P = 0.001 and r = 0.36, P = 0.021 for repeated measurements) as did PMI (r = 0.37, P = 0.019 and r = 0.38, P = 0.016 for repeated measurements). All three measurements from DPTs had limited repeatability. MCT and PMI had moderate sensitivity and specificity for diagnosis of low mandibular BMD. Using ROC analysis, MCT and PMI measurements of one observer were significantly more valid than densitometry for diagnosis of low mandibular BMD. CONCLUSIONS: It may be feasible to use MCT and PMI as diagnostic indicators of mandibular BMD, but further work is required to overcome problems with repeatability and to provide a larger patient sample.

Absorptiometry, Photon↗
PubMed1998

The relationships between two indices of mandibular bone quality and bone mineral density measured by dual energy X-ray absorptiometry.

OBJECTIVES: To establish whether a relationship exists between the bone quality index (BQI), the mandibular cortical index (MCI) and bone mineral density (BMD) of the body of the mandible as measured by dual energy X-ray absorptiometry (DXA). METHODS: Mandibular DXA and panoramic radiography were performed on 40 edentulous female patients. Mandibular body BMD was calculated by manual analysis of DXA scans. Panoramic radiographic appearances of the mandibles were assessed according to the BQI and MCI. All assessments were performed by two observers. RESULTS: There were significant correlations between BQI and BMD (P < 0.01 for both observers) and between MCI and BMD (P < 0.005), but MCI was the more dominant of the two variables. Inter-observer agreement between BQI assessments was superior to that between MCI assessments. There were marked differences between intra-observer agreement for the two observers for both indices. CONCLUSIONS: Both BQI and MCI are significantly related to BMD. However, particularly in the case of MCI, there were problems in repeatability of assessments which might limit their use in clinical practice.

Absorptiometry, Photon↗
PubMed1998

A digital subtraction radiography investigation of upper first molar proximal bone density changes in adolescents.

The aim of this in vivo study was to investigate the ability of digital subtraction radiography to monitor changes in proximal bone density, adjacent to the upper first molars, in a group of adolescents using the Digora direct digital radiographic system to acquire images. For 57 adolescents, assessments of changes in probing attachment level at the mesio- and disto-buccal surfaces of both upper first molars and proximal crestal bone density using digital subtraction radiography were made. At the conclusion of this 21-month study attachment loss was identified in 34 (17%) of the 204 sites analysed. For sites with attachment loss a mean decrease in bone density equivalent to 5.51 mm3 aluminium (Al) was found compared to 2.96 mm3 Al for those without (p < 0.001). For the 17 subjects with attachment loss a mean equivalent to 4.66 mm3 Al was lost from the crestal bone compared with 2.56 mm3 Al for the 40 subjects without attachment loss (p < 0.01). The correlation between attachment loss and bone density changes was poor for both sites (r = 0.13), p = 0.067) and mean scores for subjects (r = 0.24, p = 0.069). A visual qualitative assessment of bone density change found that 70.6% of sites with attachment loss compared to 62.4% of those without had a decrease in crestal bone density. This study suggests that it is possible to monitor bone density changes in adolescents, with a developing dentition, using digital subtraction radiography. Further, it is suggested that conventional probing assessments of attachment level may underestimate the level of destructive periodontal disease in this age group.

Adolescent↗
PubMed1997

Panoramic mandibular index as a radiomorphometric tool: an assessment of precision.

OBJECTIVES: To evaluate the intra-observer repeatability and inter-observer reproducibility of the measurements used in deriving the Panoramic Mandibular Index (PMI). METHODS: Two observers measured 21 dental panoramic radiographs independently of each other, both repeating the measurements after a period of 1 week. The measurements were then evaluated using a number of statistical methods. RESULTS: All sets of compared measurements, both within and between observers, demonstrated significant positive correlations, with no significant difference between measurements Precision, however, was poor and variable. CONCLUSION: The main difficulties in obtaining consistency in repeated measurements were related to individual morphology and radiodensity. In order to improve the validity of the PMI as a measure of local bone loss, repeatability of the measurements should be improved. Suggestions as to how this, might be achieved are discussed.

Absorptiometry, Photon↗
PubMed1996

The potential medico-legal implications of computed radiography.

Computed radiographic (CR) systems are available which allow dentists to obtain direct digital intra-oral images. These CR images, however, can be readily altered using image processing software. This paper demonstrates the potential medico-legal problems of image manipulation and calls for manufacturers of CR equipment to be pressed to explore methods of preventing such abuse.

Computer Security↗
PubMed1996

The use of panoramic radiology in dental practice.

OBJECTIVES: Approximately 1.5 million panoramic radiographs are taken annually in the general dental service in England and Wales. The aim of this review was to assess the clinical role of panoramic radiology in the diagnosis of diseases associated with the teeth and to consider its value in routine screening of patients. METHOD: This was carried out by critical review of the literature. RESULTS: In addition to common problems with radiographic technique and processing, there are limitations in image quality inherent to panoramic radiology. These factors contribute to a reduced diagnostic accuracy for caries diagnosis, demonstration of periodontal bone support and periapical pathology when compared with intraoral radiography. Routine screening is unproductive for large proportions of dentate and edentulous populations, while in those cases where pathology is detected the diagnostic accuracy can be questioned. Furthermore, the "detection' of asymptomatic anomalies may have no effect on patient management. Attempts to develop and test panoramic radiographic selection criteria are reviewed. CONCLUSIONS: New, high-yield selection criteria for panoramic radiography are proposed as a means of reducing unnecessary examinations, limiting radiation doses and reducing financial costs to patients and health service providers. However, research is indicated to develop further and to test such selection criteria.

Alveolar Bone Loss↗
PubMed1996

A two-centre study to determine dentists' agreement with current guidelines on the frequency of bitewing radiography.

The main aim of this study was to compare the intervals between initial and recall bitewing radiography recommended by general dental practitioners (GDPs) with those advocated in published guidelines. A questionnaire containing eight clinical scenarios was distributed to GDPs in two areas of England, Birmingham (fluoridated) and Manchester (non-fluoridated). The response rate was 70.8%. There was considerable agreement (> 66.0%) with recommended guidelines for all low caries risk scenarios, but in three out of the four high caries risk scenarios a minority of dentists were in agreement (< 49.5%). In high caries risk scenarios there was a tendency to over prescription with adult patients and under-prescription for patients in the mixed dentition. For all low risk scenarios except the youngest patient, there was a significantly greater agreement with the guidelines amongst Birmingham dentists, with the Manchester group having a greater tendency to over-prescription. This difference may be related to the effects of fluoridation of the water supply in the Birmingham area. There was generally greater agreement with the guidelines amongst younger dentists, with their older colleagues tending to under-prescription. The results suggest that greater emphasis on selection criteria in continuing education of dentists is required.

Adolescent↗
PubMed1996

Factors influencing the frequency of bitewing radiography in general dental practice.

The aim of this study was to determine the influence of a range of patient and dentist factors on the prescription of bitewing radiography. A postal questionnaire of general dental practitioners working in the Birmingham and Manchester areas of England was used. Dentists were requested to score the influence of 15 factors upon their decision whether or not to take bitewing radiographs. Some of these factors were chosen to represent accepted "high caries risk" factors, some "low risk" factors, while others were chosen as they should be irrelevant to prescription of bitewing radiographs. There was a questionnaire response of 70.8%. Dentists recognized accepted high caries risk factors as being an indicator for bitewing radiography but the influence of low caries risk factors was less clear. Only "good oral hygiene" and the presence of "few restorations" were perceived as relevant to bitewing prescription, while fissure sealants were seen as an influence in favour of radiography by almost one third of dentists. Dentists tended to be influenced in their radiographic practice by the opinions of patients and fears of medico-legal consequences. Pregnancy was seen as contra-indicatory for bitewings by almost all dentists. These results suggest that greater emphasis should be placed upon radiographic selection criteria in dental education.

Adult↗
PubMed1996

Florid oral manifestations in an atypical familial adenomatous polyposis family with late presentation of colorectal polyps.

Early identification and prophylactic surgery are essential in preventing development of malignancy in colorectal polyps in familial adenomatous polyposis (FAP). Previous studies indicate a 100% cumulative risk of developing colonic polyps in individuals with FAP by the age of 34 yr. However, we have previously reported late-onset and non-penetrance of polyposis in four families. We describe here in detail one of these families with florid oral manifestations detectable on panoramic radiography of the jaws, which were instrumental in the diagnosis of FAP in the index patient and for ascertainment of her family for screening. The pathological adenomatous polyposis coli (APC) gene mutation in this family was shown to segregate with dento-osseous changes. Panoramic jaw radiography is a common examination carried out prior to dental or oral surgical procedures. This case illustrates the importance of appropriate investigations, including family history and colonoscopy, even in relatively older patients with radiological findings such as those described here and in members of their families at risk of FAP.

Adenomatous Polyposis Coli↗
PubMed1996

Sensitometric and image quality performance of "rapid" intraoral film processing techniques.

A number of products are available to dentists for the rapid production of intraoral radiographic films but there is little information on their relative merits. This study evaluated the performance of five "rapid" film processing products commonly used by British dentists in comparison with standard Kodak manual processing. Two Perspex contrast-detail test objects were made in order to investigate threshold contrast. Film speed, film gradient, limiting resolution and threshold contrast results are presented. Rapid processing systems possessed lower film speed when compared with Kodak Ektaspeed film and standard Kodak processing. The speed of E-speed film was found to be lower than that of D-speed film when used with Westone "Rapid X-ray" processing. Overall image quality was generally similar for all film/processing combinations evaluated, with the exception of Nix QP which gave markedly poorer image quality.

Humans↗
PubMed1996

The imaging performance of a storage phosphor system for dental radiography.

Direct digital imaging systems are becoming increasingly common in dental radiography. The majority of these systems are based on charge coupled device (CCD) technology. A relatively new system, based on photo-stimulable phosphor luminescence (PSPL), is now commercially available. This system appears to overcome some of the restrictions of CCD systems including those associated with the bulky detector, connecting wire, limited image size and limited exposure latitude. A physical evaluation of the PSPL system was conducted including measurements of sensitometric response, modulation transfer function (MTF), noise power spectrum (NPS), noise equivalent quanta (NEQ) and detective quantum efficiency (DQE). These measurements were compared with results obtained previously for Kodak Ektaspeed (E-speed) film. The results of the evaluation indicate that the PSPL system may be capable of operating at exposures up to 80% lower than for film with comparable image quality.

Humans↗
PubMed1996

Mandibular bone mineral density as a predictor of skeletal osteoporosis.

A considerable amount of work has been performed on methods of detecting individuals with low bone mass at an early stage. Some researchers have considered if dental radiographs could have a role in the detection of individuals with osteoporosis. A basic requirement for this would be that bone mass in the jaw relates significantly to that of other skeletal sites in which osteoporosis is a significant problem. The first aim of this study was to investigate the relationship between mandibular bone mineral density (BMD) and that of other skeletal sites commonly used for bone densitometry in the detection of osteoporosis. The second aim was to assess the validity of mandibular BMD as a predictor of BMD in these other sites. 40 edentulous females underwent dual energy X-ray absorptiometry (DXA) of the lumbar spine (L2-L4), DXA of the right femoral neck, single photon absorptiometry (SPA) of the proximal and distal forearm and DXA of the mandible. Significant correlations were observed between BMD in the mandibular body, ramus and symphysis and all other skeletal sites (p < 0.02). Five patients (12.5%) had age matched Z-scores of -1.0 or lower in all three non-mandibular sites (lumbar spine, femoral neck and forearm). Using these patients as the proportion of the population with a positive finding of "low bone mass", the sensitivity and specificity of mandibular BMD in predicting low bone mass for these patients was determined. Where a diagnostic threshold for low mandibular BMD was set at one standard deviation below the mean, the mandibular body BMD measurement gave high sensitivity (0.8) and specificity (0.97), the symphysis BMD low sensitivity (0.4) but a high specificity (0.77), while the ramus BMD had a moderate level of sensitivity (0.6) and high specificity (0.91). It is concluded that mandibular BMD assessed by DXA correlates significantly with BMD measurements of other important skeletal sites. The higher correlation coefficients and the greater sensitivity and specificity for the body of mandible suggest that this site should be used for any potential clinical application of dental radiographs in detection of osteoporosis.

Absorptiometry, Photon↗
PubMed1995

The impact of quality control on radiography in general dental practice.

The aim of this study was to assess the impact of two quality control measures upon the quality of periapical radiographs in general dental practices. Five general dental practitioners took part in the study. Periapical radiographic quality was assessed before and after the introduction of film holders and quality control measures for processing. Prior to the introduction of the quality control measures, 49% of radiographs were assessed as being 'unacceptable', 49% exhibited faults but were 'acceptable' for diagnostic purposes, while only 2% of radiographs were 'excellent' being entirely free of faults. After the introduction of film holders and processing quality control procedures 39% were 'unacceptable' (P < 0.05), 56% were 'acceptable' and 5% of radiographs were classified as 'excellent'. It is concluded that current recommendations to dentists to use film holders and to carry out processing quality control are justified in terms of an improvement in the diagnostic quality of radiographs. However, improvements in undergraduate and continuing education for all members of the dental team, with emphasis on practical 'hands-on' instruction, may improve the effectiveness of these recommendations.

Chi-Square Distribution↗
PubMed1995

Some factors affecting the standards of radiography in general dental practice.

This study had three aims. The first was to examine the influence of legislative and educational factors on facilities and equipment in dental practices, the second to find out if these and practice size affected standards and the third to assess the degree to which technique and other faults not connected with processing accounted for inadequate diagnostic quality in intra-oral radiography. Dentists from 62 practices returned questionnaires about the sizes of their practices, facilities and equipment for radiography and relevant updating, training and education of their staff. The quality of 305 radiographs taken in a sample of 11 practices was assessed. Ten examples of good radiographic practice were used to evaluate standards in the general practices. The 'good practice score' ranged from 2 (two practices) to 10 (one practice) with a mean of 6.2. Practices whose principals had engaged in the recommended educational activities scored more highly than those that had not (P < 0.05), and the mean scores in practices of two or more dentists were higher than in single-handed (P < 0.05). Of the 305 radiographs, the dentists, without the use of criteria to assess them, rejected 13.8%; with criteria they rejected 39.3% (P < 0.05). The researcher rejected 63.9% (P < 0.05). All films were processed under controlled conditions and it is likely that reject rates would have been higher under normal processing conditions. It is concluded that the use of criteria to assess radiographs and acceptance of postgraduate opportunities, particularly by single-handed practitioners, would improve the conduct of radiography. Further improvements might be gained by orienting updating courses and materials towards behavioural change.

Education, Dental, Continuing↗
PubMed1995

A laboratory evaluation of Ektaspeed Plus dental X-ray film.

OBJECTIVES: The aim of this study was to make a laboratory evaluation of the image quality of a new dental X-ray film, Ektaspeed Plus, compared with Ektaspeed and Ultraspeed films. METHODS: Films of each emulsion type underwent a range of exposures at both 50 kVp and 70 kVp, and characteristic curves were constructed to give a comparison of fog, speed and contrast. Line pair and contrast detail test objects were used to assess the resolution of radiographs and the ability of the two film types to reproduce minor differences in subject contrast. The sensitivity of the emulsions to safelighting for a range of times was also tested. RESULTS: Ektaspeed Plus had the same speed, a slightly higher base plus fog density but a higher contrast (50 and 70 kVp) than Ektaspeed. The speed of Ektaspeed Plus was higher and the contrast similar to that of Ultraspeed film. Limiting resolutions of the three films were the same. There was a slightly better imaging of one contrast detail phantom with Ektaspeed Plus compared to Ektaspeed at 70 kVp only. All three emulsions were insensitive to recommended safelighting conditions. CONCLUSION: The improved image contrast of Ektaspeed Plus may be more acceptable to dentists than Ektaspeed and lead to a greater acceptance of E-speed film, contributing to dose reduction.

Emulsions↗
PubMed1995

An in vitro comparison of 10 radiographic methods for working length estimation.

The aim of this in vitro study was to assess the efficacy of 10 currently available methods of producing radiographic images, two conventional and eight rapid, in working length estimation. Thirty extracted teeth comprising 42 root canals were mounted in blocks of poly(methylmethacrylate) and access cavities prepared. A size 15 Hedstrom file was inserted into each root canal and sealed into position. Each tooth was imaged by 10 methods: combinations of conventional (D- and E- speed) film processed with conventional manual chemistry of two proprietary brands of rapid processing chemistry (Westone Rapid Dental and Kodak 'Rapid Access'), Super X30 packet processed film, Hanshin Hi-Fi and Nix NF45-100 films processed using their respective manufacturers' monobath solutions, and the Sens-A-Ray digital X-ray system. Comparisons of length of file visible were made between the D-speed films (conventionally processed using Kodak chemistry) and the nine other radiographic methods. No significant differences in percentage length of file seen were found between D-speed film processed with conventional chemistry and E-speed film processed with the same chemistry or between D-speed film processed with with conventional chemistry and six of the rapid imaging systems studied. The percentage length of the file visible was significantly less for Sens-A-Ray (P=0.02) and for Nix NF45-100 film (P<0.005) when compared with D-speed film processed with conventional chemistry. This difference in file length is probably not of clinical importance for the Sens-A-Ray images but may be so for the Nix images.

Dental Pulp Cavity↗