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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
PubMed1999

Canalis sinuosus mimicking a periapical inflammatory lesion.

A case is presented in which an anatomical feature, canalis sinuosus, manifested as a periapical radiolucency on an upper canine. This may have been interpreted as an inflammatory lesion and led to the patient receiving inappropriate treatment had a further radiograph not been taken. The incisive foramen and mental foramen are well known anatomical features which may mimic periapical inflammatory lesions but it is less common for a neurovascular canal to manifest as a periapical radiolucency on an upper canine.

Adult↗
PubMed1999

Aspects of panoramic radiography in general dental practice.

OBJECTIVES: To gather information on the types of panoramic x-ray equipment used in NHS dental practice and whether dentists satisfy the legal requirements for safety, to determine which practice personnel take panoramic radiographs and to assess the prevalence of the practice of 'routine' panoramic radiography among NHS dentists. DESIGN: Postal questionnaire survey of general dental practitioners carried out during 1997 in selected FHSAs in England and Wales. RESULTS: 542 dentists returned the questionnaire, a 73.3% response. Panoramic x-ray equipment ranged in age from 27 years old to new, with 42.2% exceeding 10 years in age. The overwhelming majority of GDPs satisfied the requirement for regular maintenance and surveying of equipment. Almost all dentists (95.9%) performed a history and clinical examination prior to panoramic radiography but 42% practised 'routine screening' of new adult patients. A substantial proportion (36.7%) of dentists used unqualified personnel to take panoramic radiographs. CONCLUSIONS: While some aspects of this study give reassurance about the prevalence of good practice, widespread panoramic screening and using unqualified staff to take radiographs causes concern. These findings have implications for educators and for those involved in maintaining clinical standards.

Adult↗
PubMed1999

Factors influencing the selection of panoramic radiography in general dental practice.

OBJECTIVES: To identify factors influencing dentists' decisions to take panoramic radiographs and to determine dentists' perceptions of the value of panoramic radiographs in the diagnosis of common dental pathologies. METHODS: Questionnaire of dentists with access to panoramic radiography equipment in 22 randomly selected Family Health Service Authorities in England and Wales. Dentists were asked to score 17 factors for their influence upon panoramic use, compare the relative diagnostic value of panoramic and intraoral radiographs for diagnosis of common dental pathologies and state their principal reasons for taking panoramic radiographs. RESULTS: The response rate to the questionnaire was 73.3%. The factors most likely to influence dentists to take a panoramic radiograph were 'planning oral surgery', 'facial trauma', 'periodontal disease', 'heavily restored dentition' and 'patient first attendance'. Dentists' opinions on the diagnostic usefulness of panoramic radiographs were in broad agreement with those in the scientific literature. The main reasons for taking panoramic radiographs were as a 'general screen' and as a 'view for unerupted or impacted teeth'. CONCLUSIONS: There are areas where dentists' prescription of panoramic radiographs is in disagreement with recent guidelines. Successful implementation of these guidelines would be likely to lead to a substantial reduction in the numbers of panoramic radiographs taken by GDPs.

Adult↗
PubMed1999

The reproducibility of the mandibular cortical index.

OBJECTIVES: To assess the reproducibility and diagnostic validity of Mandibular Cortical Index (MCI) when used by minimally trained observers. METHODS: Four 'experts' and 45 final-year dental students classified the appearance of the lower border of the mandibular cortex in 30 panoramic radiographs using the MCI. Experts viewed the original radiographs. The students received instruction in the MCI and viewed slides of the radiographs in a lecture theatre. RESULTS: For intra-observer agreement, the experts had significantly higher overall values of weighted kappa, indicating substantial agreement in MCI assessment, whereas the students showed moderate agreement. For inter-observer agreement, there was fair agreement between the experts and poor agreement between the students. Using the experts' MCI assessment as the 'gold standard', the mean sensitivity of the students in diagnosis of C3 was 0.71 (maximum 0.95, minimum 0.25) and mean specificity was 0.56 (maximum 0.9, minimum 0.20). CONCLUSIONS: The MCI has important limitations in terms of intra- and inter-observer agreement. Minimal training in its use, such as might be given in a lecture format to dentists, was ineffective and associated with poor inter-observer agreement and limited diagnostic validity in identifying signs of osteoporosis. More lengthy training and experience in using the MCI would be needed for it to be effective as a diagnostic tool in general dental practice.

Clinical Competence↗
PubMed1999

Radiomorphometric indices of the mandible in a British female population.

OBJECTIVES: To examine the radiomorphometric indices of the mandible on panoramic radiographs in a population of British female patients, to identify their normal ranges and to investigate their relationships with age, detentition and social class. METHODS: Five indices, cortical width at the gonion (GI) and below the mental foramen (MI), the panoramic mandibular index (PMI), the mandibular cortical index (MCI) and one new index (measurement of cortical width at the antegonion; AI), were measured bilaterally on 500 panoramic radiographs of females by one trained observer. The measurements were analysed for ease of application, repeatability, relationships with age, dentition and social class and interrelationships between the variables. RESULTS: All quantitative indices (GI, MI, PMI, AI), showed a significant, negative correlation with age. MCI showed an age-related distribution. Mandibular dentition exerted a significant influence on some indices, but social class had no influence. Intra-observer repeatability of MI, PMI and AI was fair (precision < 20%) but that for GI was poor. Intra-observer agreement in MCI assessments was excellent. CONCLUSIONS: The age-related changes in mandibular radiomorphometric indices and their variation within each age band lend support to their potential use in identification of skeletal osteopenia. However, problems with repeatability and measurement precision identified in the pilot study, notably with GI, may be a considerable obstacle to their use in general practice.

Adult↗
PubMed1998

A comparison of maxillary and mandibular bone mineral densities.

STATEMENT OF PROBLEM: The success rate of implant osseointegration is dependent on many factors such as bone mineral density, volume and vascularity of bone, implant design, ridge shape, and patient selection criteria among others. PURPOSE: This study examined whether a technique to measure differences in bone mineral density in the maxilla and mandible might be useful to predict the likelihood of successful osseointegration. MATERIAL AND METHODS: Bone densitometry of the jaws was performed with a densitometer, and bone mineral density was calculated at three regions of the maxilla and one site in the mandibular body in 39 edentulous subjects. RESULTS: Significant differences were found between the mean bone mineral density of each site when compared with the three other locations. The mean bone mineral density for the mandible (mean = 1.11 g.cm-2), was twice that of the anterior maxilla (mean = 0.55 g.cm-2). Both were significantly greater than the bone mineral density of the posterior maxilla (mean = 0.31 g.cm-2; including the hard palate, mean = 0.45 g.cm-2). The bone mineral densities at the three maxillary sites were all highly correlated (r > or = 0.78, p < 0.001). CONCLUSION: The dissimilarity in bone mineral density at different mandibular and maxillary sites may partly explain some variation in previously reported osseointegration rates. The posterior maxilla had the lowest bone mineral density and in certain circumstances before implant insertion, bone augmentation, or guided tissue regeneration may be advisable to improve the rate of osseointegration. Because the radiation dose is low, dual energy x-ray absorptiometry may be a useful noninvasive technique for determining the bone mineral density before implant insertion.

Absorptiometry, Photon↗
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↗