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Biomedical subjects

M R Fenlon

Publications and source records attributed to M R Fenlon.

At least 19 recordsLinked to original sources
PubMed2001

Personality of dental students in two dental schools in the United Kingdom and in Ireland.

The personality characteristics of students from two dental schools, one in the United Kingdom which admitted students using interviews, and one in Ireland which accepted students solely on examination results, were assessed using the short form of the Eysenck Personality Questionnaire. Results were compared with norms for age and sex. Personality scores of students from the Irish dental school were not significantly different from normal scores. Female and male students from the United Kingdom school scored higher than would be expected on extraversion, and male students from the same school scored lower than would be expected on neuroticism. The differences in personality between the two schools may be explained by the different methods of admission.

Adult↗
PubMed2000

Locking acrylic resin dental stent for image-guided surgery.

This article presents a procedure for fabricating a locking acrylic resin dental stent for use in image-guided base-of-skull surgery and neurosurgery. The stent offers advantages over conventional bone screw-anchored systems to surgeons and patients. In view of the increasing use of image guidance in base-of-skull surgery and neurosurgery, prosthodontists will meet a growing demand for this type of device in the future.

Acrylic Resins↗
PubMed2000

An investigation of factors influencing patients' use of new complete dentures using structural equation modelling techniques.

UNLABELLED: A review of the literature demonstrated that research had not identified a set of prognostic indicators for prospective complete denture patients, with different authors publishing contradictory results. OBJECTIVE: To investigate possible relationships between patient and clinical factors and denture wear and use of dentures for eating. METHODS: Patients attending Guy's Dental Hospital, London, for provision of complete dentures were recruited. For each patient relevant history was recorded and an examination of the edentulous mouth and existing dentures, where present, was undertaken at the beginning of treatment. At the first post-insertion appointment the edentulous mouth, previous and new dentures were examined. Three months after the review appointment patients were sent a postal questionnaire to assess patient use of dentures and patient satisfaction. Data were analysed using structural equation modelling techniques. RESULTS: 723 patients were recruited. Significant relationships were found between quality of complete dentures and patients' use of complete dentures and between quality of residual edentulous ridges and patients' use of complete dentures. These results contrast with most previous research into prognostic indicators for success in complete denture treatments. CONCLUSIONS: Quality of residual edentulous ridges and quality of new complete dentures predict patients' use of new complete dentures.

Aged↗
PubMed2000

Design and evaluation of a system for microscope-assisted guided interventions (MAGI).

The problem of providing surgical navigation using image overlays on the operative scene can be split into four main tasks--calibration of the optical system; registration of preoperative images to the patient; system and patient tracking, and display using a suitable visualization scheme. To achieve a convincing result in the magnified microscope view a very high alignment accuracy is required. We have simulated an entire image overlay system to establish the most significant sources of error and improved each of the stages involved. The microscope calibration process has been automated. We have introduced bone-implanted markers for registration and incorporated a locking acrylic dental stent (LADS) for patient tracking. The LADS can also provide a less-invasive registration device with mean target error of 0.7 mm in volunteer experiments. These improvements have significantly increased the alignment accuracy of our overlays. Phantom accuracy is 0.3-0.5 mm and clinical overlay errors were 0.5-1.0 mm on the bone fiducials and 0.5-4 mm on target structures. We have improved the graphical representation of the stereo overlays. The resulting system provides three-dimensional surgical navigation for microscope-assisted guided interventions (MAGI).

Computer Simulation↗
PubMed1999

Association between the accuracy of intermaxillary relations and complete denture usage.

STATEMENT OF PROBLEM: Previous studies have investigated possible associations between the accuracy of intermaxillary relations and complete denture usage with variable results. PURPOSE: This study investigated the association between the intermaxillary relations in new complete dentures and the use of these dentures for daily wear and eating. METHODS: A prospective study of patients (n = 523) attending Guy's Dental Hospital for complete dentures was undertaken. Patients were examined at the beginning of treatment and at the first post insertion visit. Rest vertical dimension and vertical dimension of occlusion were measured with a Willis gauge. Quality of registration of centric relation position was assessed and, 3 months later, a postal questionnaire was sent to investigate patients' use of dentures. Data were analyzed with Pearson's chi-squared test with exact nonparametric inference. RESULTS: Adequate interocclusal rest space was associated with daily wear of dentures (chi2 = 7.97, P =. 018). Quality of registration of centric relation was associated with daily wear (chi2 = 32.43, P <.001) and use of dentures for eating (chi2 = 20.23, P =.003). CONCLUSION: Positive associations were found between the accuracy of intermaxillary relations and complete denture usage.

Aged↗
PubMed1999

A system for microscope-assisted guided interventions.

We present a system for surgical navigation using stereo overlays in the operating microscope aligned to the operative scene. This augmented reality system provides 3D information about nearby structures and offers a significant advancement over pointer-based guidance, which provides only the location of one point and requires the surgeon to look away from the operative scene. With a previous version of this system, we demonstrated feasibility, but it became clear that to achieve convincing guidance through the magnified microscope view, a very high alignment accuracy was required. We have made progress with several aspects of the system, including automated calibration, error simulation, bone-implanted fiducials and a dental attachment for tracking. We have performed experiments to establish the visual display parameters required to perceive overlaid structures beneath the operative surface. Easy perception of real and virtual structures with the correct transparency has been demonstrated in a laboratory and through the microscope. The result is a system with a predicted accuracy of 0.9 mm and phantom errors of 0.5 mm. In clinical practice errors are 0.5-1.5 mm, rising to 2-4 mm when brain deformation occurs.

Bone Cysts↗
PubMed1999

Operator agreement in the use of a descriptive index of edentulous alveolar ridge form.

CAWOOD & HOWELL have proposed a classification of the anatomical form of the residual alveolar processes of edentulous patients. The purpose of this study was to test observer agreement in the clinical assessment of edentulous alveolar ridge form using this classification. This was tested in a pilot study involving 57 edentulous patients, and subsequently in a study of 557 edentulous patients. High levels of observer agreement were found when using this classification for upper and lower edentulous alveolar ridges, suggesting that the classification may be useful as a research tool.

Alveolar Bone Loss↗
PubMed1999

Stereo augmented reality in the surgical microscope.

We present an augmented reality system that allows surgeons to view features from preoperative radiological images accurately overlaid in stereo in the optical path of a surgical microscope. The purpose of the system is to show the surgeon structures beneath the viewed surface in the correct 3-D position. The technical challenges are registration, tracking, calibration and visualisation. For patient registration, or alignment to preoperative images, we use bone-implanted markers and a dental splint is used for patient tracking. Both microscope and patient are tracked by an optical localiser. Calibration uses an accurately manufactured object with high contrast circular markers which are identified automatically. All ten camera parameters are modelled as a bivariate polynomial function of zoom and focus. The overall system has a theoretical overlay accuracy of better than 1 mm. Implementations of the system have been tested on seven patients. Recent measurements in the operating room conformed to our accuracy predictions. For visualisation the system has been implemented on a graphics workstation to enable high frame rates with a variety of rendering schemes. Several issues of 3-D depth perception remain unsolved, but early results suggest that perception of structures in the correct 3-D position beneath the viewed surface is possible.

Depth Perception↗
PubMed1999

Operator agreement in the use of a descriptive index of complete denture quality.

BACKGROUND AND DESIGN: No generally accepted method for classification of clinical quality of complete dentures exists. While various methods have been proposed, little effort has been made to test observer agreement. The purpose of this study was to test observer agreement in the clinical assessment of complete denture quality using a systematic classification. RESULTS: Fifty seven (57) complete denture-wearing patients were examined on two occasions separated by two weeks. Observer agreement was measured using Cohen's? (kappa). High levels of observer agreement were found for upper and lower retention and stability and for quality of retruded jaw relationship. CONCLUSION: High levels of operator agreement were found for a method for classification of clinical quality of complete dentures suggesting that the classification may be useful as a research tool.

Denture Retention↗
PubMed1999

Comparison of patients' appreciation of 500 complete dentures and clinical assessment of quality.

To compare patients' appreciation and clinical assessment of quality of complete dentures 500 patients attending a dental teaching hospital for provision of new complete dentures were recruited. In each case denture quality was assessed by an experienced prosthodontist using a validated classification of aspects of denture quality. Patients graded their appreciation of features of the dentures on a four point scale. Multiple correspondence analysis demonstrated close correspondence between dentist and patient appreciation of dentures when the dentures were rated as poor, but little or no correspondence when dentists or patients rated the dentures highly.

Attitude of Health Personnel↗
PubMed1998

Factors associated with the presence of denture related stomatitis in complete denture wearers: a preliminary investigation.

Various factors have been associated with the presence of denture related stomatitis. These include local factors such as continuous denture wear, trauma from dentures and poor denture hygiene Systemic factors, use of various pharmacological agents and smoking have also been implicated. This investigation involved history taking and examination of 250 patients attending Guy's Hospital for the construction of complete dentures. No association was found between systemic factors, use of pharmacological agents or smoking and the presence of denture related stomatitis. Night wear of complete dentures was found to be significantly associated with the prevalence of denture related stomatitis.

Chi-Square Distribution↗
PubMed1994

A controlled clinical, electromyographic, and kinesiographic assessment of craniomandibular disorders in women.

Clinical, electromyographic, and kinesiographic methods were used to evaluate 35 female patients presenting with craniomandibular disorders. Twenty-six similarly aged, symptom-free women served as controls. Clinical assessments showed that the patients demonstrated a higher prevalence of bruxism than did the controls. Electromyographic results suggested that the rest activity of patients' elevators was significantly greater than that of the controls. Kinesiographic measurements showed that the patient group demonstrated greater vertical and anterior posterior movements from rest to centric occlusion than did the control group, and both the average and maximum opening velocities were smaller in patients than in controls.

Adult↗
PubMed1993

Accuracy of fit of cobalt-chromium removable partial denture frameworks on master casts.

Fifty-six cobalt-chromium removable partial denture frameworks made to the same design were found to fit their master casts poorly. Spaces were significantly greater between palatal aspects of abutment teeth and palatal reciprocal arms, and between buccal aspects of occlusal rests and rest seats. Excessive contraction towards the centre of the palate was found. Expansion of the refractory investment may not have compensated adequately for solidification and cooling contraction of the cobalt-chromium alloy. Although dimensional changes in investment and casting are by volume, no evidence of anisotropic expansion of castings in a vertical direction was found.

Chromium Alloys↗
PubMed1992

Validity of a patient self-completed health questionnaire in a primary care dental practice.

1500 patient medical histories derived from self-completed health questionnaires alone and from a combination of questionnaire, structured interview by a dentist, and selective reference to family doctors were compared. In 4.25% of cases, the questionnaire medical history was significantly deficient. Such questionnaires yield an inadequate medical history when used on their own.

Age Factors↗
PubMed1991

Medical status of patients attending a primary care dental practice in Ireland.

Medical status of 1,500 patients attending a primary health care dental practice was examined by means of patient self-completed health questionnaire and by structured verbal interview by a dentist. Relevant medical histories and/or drug therapies affecting the practices of dentistry were found in 27.7% of patients. Problems identified included cardiovascular disease (10.4%), endocarditis risks (5.8%), hepatitis (7.9%), leukaemias (0.3%), bleeding tendencies (3%), drug allergies (7.0%), including penicillin allergy (3.6%) and intake of drugs affecting dentistry (6.0%). For most of these categories there was a marked increase in prevalence with increasing age and many categories contained many more women than could be expected from the male/female distribution of the total patient group.

Adolescent↗
PubMed1989

Medical screening of 1500 patients in a dental surgery: a prospective study.

Communication between medical and dental practitioners about patients they have in common enhances total patient care, but such communication rarely occurs. This may be due to lack of appreciation by doctors of the medical risks to certain patients undergoing dental treatment. To ascertain a relevant medical history, prospective medical screening was performed on 1500 new patients attending a general dental practice using a standard health questionnaire followed by an interview between the patient and dentist. There were 382 (25.5%) patients with a current or past medical history of relevance to dentistry, 90 (6.0%) were taking medication of potential importance and 105 (7.0%) considered they had an intolerance to certain drugs. The screening provided a patient data base for medical and medico-legal purposes. A total of 376 (25.1%) questionnaires were filled out incorrectly and 63 of these (16.8%) had major misinformation about medical history. A small but important group deliberately misled the dentist either from fear of refusal of treatment or embarrassment about their medical history. Therefore interviews are an essential adjunct to written health questionnaires in eliciting accurate information. Formal screening of new patients is essential in general dental practice. Furthermore, general medical practitioners need to become aware of the common risks to patients undergoing dentistry. Better formal and informal communication between general medical and dental practitioners is recommended for the benefit of their mutual patients.

Communication↗