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Biomedical subjects

K Horner

Publications and source records attributed to K Horner.

At least 19 recordsLinked to original sources
PubMed2001

Screening panoramic radiology of adults in general dental practice: radiological findings.

AIM: To identify the radiological findings from routine screening panoramic radiographs taken of adult (> or = 18 years) patients in general dental practice. METHOD: Forty-one general dental practitioners (GDPs) who routinely took panoramic radiographs of all new adult patients were recruited. In total, they submitted 1,818 panoramic radiographs of consecutive patients along with basic patient information, radiological reports and treatment plans. The radiographs were also reported by 'experts' (consensus of two dental radiologists). Radiological findings were recorded from the GDP assessments (dentist RY), the experts (expert RY), after exclusion of findings that would have been seen on posterior bitewing radiographs (MRY) and after exclusion of findings of no relevance to treatment (MRYT). RESULTS: There was no significant difference in age profile between the study sample and Dental Practice Board population figures (P = 0.26). No radiographs other than the panoramic radiograph had been taken for 57.1% of patients. For the GDP assessments, only 4.6% of patients had radiographs with no radiological findings, while for the experts this proportion was 3.1%. With the exception of the assessment of periodontal bone loss, the experts diagnosed significantly greater proportions of cases as having positive radiological findings. Agreement between dentist and expert assessments varied greatly. When findings from bitewing radiographs were excluded, no radiological findings were recorded on the radiographs of 17.2% of patients. When proposed treatment plans were taken into account, the majority of patients' radiographs (56.3%) had no radiological findings of relevance to treatment. CONCLUSIONS: The choice of radiographic examination for the majority of patients in the study did not follow current guidelines. Dentists diagnosed fewer abnormalities than did experts. While many radiological findings are revealed by panoramic radiography, these may either duplicate information from bitewing radiographs or are often of no significance to treatment planning. This study did not provide evidence to support the practice of routine panoramic radiography of all new adult patients.

Adult↗
PubMed2001

Variability in measurement of radiomorphometric indices by general dental practitioners.

OBJECTIVES: To assess the variability of general dental practitioners (GDPs) in measurement of radiomorphometric indices on panoramic radiographs following basic instruction and to examine whether the variability could be reduced by more individualised instruction. METHODS: Nine GDPs measured Gonion Index (GI), Antegonion Index (AI), Mental Index (MI) and Mandibular Cortical Index (MCI) on copies of 10 panoramic radiographs following a lecture on osteoporosis and the use of radiomorphometric indices. Their measurements were related to expert-derived measurements of the same copy radiographs. Mean differences and limits of agreement (2x standard deviation of differences) were calculated for quantitative indices (GI, AI, MI) and agreement of GDPs with expert-derived MCI assessments was determined using weighted kappa. Following individualised feedback to GDPs, all measurements were repeated after 2 weeks and the statistical analysis repeated. RESULTS: There was extensive variation amongst GDPs in measurement of GI, AI and MI and in assessment of MCI. There was a general tendency of GDPs to record thicker mandibular cortices than did the experts. Limits of agreement were wide relative to the mean values of each quantitative index at both readings. Agreement of the GDPs with experts in assessment of MCI was moderate at both readings, but with a wide range in assessment. CONCLUSIONS: Variability in measuring radiomorphometric indices amongst the GDPs was high and was not predictably improved by individualised instruction. This study casts considerable doubt on the potential value of radiomorphometric indices given their lack of precision.

Clinical Competence↗
PubMed2001

Three phosphor plate systems and film compared for imaging root canals.

AIM: The aim of this study was to compare three phosphor plate intraoral imaging systems (Digora (DA), Digident (DT), Denoptix (DX)) and E-speed conventional film (CF) for the imaging of root canals. METHODOLOGY: Sixty extracted permanent teeth were exposed using CF, DA, DT and DX. The length of root canal visible from its most apical extent to a line drawn at the level of the cementoenamel junction was measured and this was expressed as a percentage of the distance between the radiographic apex and the cementoenamel line. All images were examined concurrently by two examiners. Films were viewed under standardized conditions and DA, DT and DX images were viewed directly from the monitor screen. The images on the monitor were enhanced to give the subjectively clearest image. RESULTS: The mean percentage of canal visible on CF was 90%, DA 78%, DT 81% and DX 83%. The difference was significant for CF-DA (P < 0.001) and CF-DT (P = 0.001). There was no statistically significant difference for CF-DX or between any of the three phosphor plate imaging systems. CONCLUSIONS: It is concluded that a greater length of root canal was visible on conventional film than on three phosphor plate imaging systems and that this may be of clinical significance.

Analysis of Variance↗
PubMed2000

The influence of viewing conditions on radiological diagnosis of periapical inflammation.

OBJECTIVES: To determine the effect of viewing conditions upon diagnosis of early periapical inflammatory pathosis on intra-oral radiographs, and to examine the effect of observer experience upon diagnostic performance in this task. METHODS: 50 observers examined 18 periapical radiographs using three different viewing conditions (room lighting; viewing box; viewing box with x2 magnification and masking). Their diagnoses were compared with an 'expert' diagnosis provided by repeated viewings of the films by two dental radiologists. Sensitivities and specificities were determined. RESULTS: When 'ideal' viewing conditions were used, optimal sensitivity (78%) and specificity (78%) were obtained. Use of a viewing box was associated with significantly higher specificity than the use of room lighting (P = 0.0016). Use of masking and x2 magnification was associated with significantly higher sensitivity than a viewing box alone (P = 0.004). There were few significant differences in diagnostic performance between observers, but qualified dental staff had significantly higher specificities than 4th year (P = 0.01) and 5th year (P = 0.01) students when a viewing box was used alone. CONCLUSIONS: This study on early periapical inflammatory pathosis gives support to guidelines which recommend the use of a viewing box, x2 magnification and masking for interpreting intra-oral radiographs. It also suggests that observer experience may influence interpretation of early periapical pathosis.

Clinical Competence↗
PubMed2000

Multiple Stafne bone cavities: a diagnostic dilemma.

Salivary gland inclusions in the mandible are relatively uncommon. If defects occur they are generally unilateral, although bilateral cases have been reported. This article describes an unusual case in which the dental panoramic tomogram revealed three radiolucent areas in the mandible. The diagnosis of the two posterior radiolucencies was confirmed as Stafne's bone cavities but a definite diagnosis for the parasymphyseal lesion remained elusive, even after surgery. However, Stafne's bone cavities are known to occur in this region and this diagnosis remains the most probable.

Diagnosis, Differential↗
PubMed1999

The quality of panoramic radiographs in a sample of general dental practices.

OBJECTIVE: To assess the quality of panoramic radiographs in a sample of general dental practices, to determine the relative frequency of errors and to identify those errors directly responsible for diagnostically inadequate images. MATERIALS AND METHODS: Examination of 1,813 panoramic radiographs obtained from 41 general dental practitioners and recording of faults. The study was carried out in 1998. Radiographs were judged as being 'excellent', 'diagnostically acceptable' or 'unacceptable'. RESULTS: Only 0.8% of films were 'excellent', 66.2% were 'diagnostically acceptable' and 33% were 'unacceptable'. The most common faults which directly contributed to failure of the radiographs were antero-posterior positioning errors, low density and low contrast. CONCLUSIONS: The quality of panoramic radiographs was considerably lower than standards recently set for primary dental care. The quality of panoramic radiography could be improved by careful attention to radiographic technique and processing.

Adolescent↗
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↗