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Biomedical subjects

W J Kerr

Publications and source records attributed to W J Kerr.

At least 19 recordsLinked to original sources
PubMed1998

The laryngeal mask as an antipollution device.

Anaesthetic pollution is still a problem and recent UK Control of Substances Hazardous to Health (COSHH) recommendations require employers to attempt to control the risk. Fifteen day-case urology operating lists were studied to compare the level of nitrous oxide exposure using face mask or laryngeal mask anaesthesia. Nitrous oxide was avoided in one group until the laryngeal mask was inserted. The use of the laryngeal mask airway showed a significant reduction in the level of pollution, such that recent COSHH recommendations were attained. However, (US) NIOSH levels were only reliably attained by avoiding nitrous oxide until the laryngeal mask was inserted. The laryngeal mask was therefore shown to be a reliable antipollution device.

Air Pollutants, Occupational↗
PubMed1997

CASES--clinical audit; scenarios for evaluation and study.

CASES, an audit and continuing education programme, evaluated aspects of current orthodontic practice and allowed orthodontists to identify areas where their practice differed from regional and national results. Evaluation of the CASES programme verified its value in audit and continuing education and the authors hope it will encourage similar projects in other disciplines too.

Adolescent↗
PubMed1997

Appliance wear: the patient's point of view.

Fifty-two patients (35 female, 17 male) completed questionnaires related to their experiences during the first 7 days of appliance wear (31 fixed, 21 removable) and then after 14 and 90 days. Most problems relating to discomfort and pain resolved within 4-7 days. The problems encountered with fixed appliances were generally more severe than with removable appliances. Swallowing and speech were more difficult with removable appliances and these problems persisted to some degree. Surprisingly, the embarrassment caused by wearing the appliance in public was similar whether it was fixed or removable.

Adaptation, Physiological↗
PubMed1996

The use of removable orthodontic appliances in the General Dental Service.

One hundred and fifty removable appliance cases consecutively sampled by the Scottish Dental Practice Board were analysed using the PAR index. The cases were assessed as being suited or unsuited to the removable appliance approach based on the presenting features previously shown to be effectively treated by removable appliances. Using chi-squared tests of association, suitable cases were characterised as being in the mixed dentition, had one feature treated and one appliance used. Suitable cases on average showed 3-4 PAR points more improvement as a result of treatment than equivalent unsuitable cases; regression equations are given. Because of the wide variability within the sample it proved impossible to predict accurately the expected duration of treatment in the General Dental Service.

Child↗
PubMed1996

A method of measuring the apical base.

The maxillary and mandibular apical base areas were measured, using a gnathograph, on the study casts of 156 adults and children representing Class II division 1, Class II division 2 and Class III malocclusions. There were significant differences between the groups at each age. The maxillary apical base areas tended to be smaller for the adults than for the children in all three occlusal classes. By contrast, the mandibular apical base areas tended to be larger for the adults than for the children, except in Class II division 1 malocclusion. Following a logarithmic transformation to stabilize the variance, regression lines were fitted to relate the size of the maxillary and mandibular apical bases to one another, for the malocclusion groups within each age group. The method gives additional information regarding the degree of apical base discrepancy in a given case, but more work is required before it can be used as a diagnostic tool.

Adolescent↗
PubMed1996

Factors associated with the standard and duration of orthodontic treatment.

The pretreatment and post-treatment study casts and records of 156 completed fixed appliance and removable appliance cases were analysed, and the influence of various factors on the standard of result, as measured by the change in PAR score produced by treatment and the duration of treatment, was assessed. For the purpose of analysis the sample was divided into two groups; a two-arch fixed appliance group (n = 81) and a removable/mini fixed appliance group (n = 75). Multiple regression procedures were carried out separately for both groups, first, with all gathered data and, secondly, with only information which would be known at the start of treatment. For fixed appliances the initial PAR score was consistently an influential variable on change in PAR score and duration of treatment. Patient compliance, the need to extract a permanent first molar and the presence of an anterior crossbite were also important. The initial PAR score also explained much of the variation in change in PAR for removable/mini fixed appliances, but generally, regression models for this group were less well fitting.

Adolescent↗
PubMed1995

An evaluation of two concentrations of hyaluronidase for supplementation of peribulbar anaesthesia.

We studied the effect of the addition of hyaluronidase to a mixture of lignocaine 2% and bupivacaine 0.75% for peribulbar anaesthesia in 60 patients presenting for elective intra-ocular surgery. Using a randomised, double-blind design, patients were allocated to one of three groups: no hyaluronidase (group A) (n = 20); hyaluronidase 50 iu.ml-1 (group B) (n = 20); hyaluronidase 150 iu.ml-1 (group C) (n = 20). The speed of onset of the block, the presence of akinesia, analgesia and the need for supplementary injections were assessed. The addition of 150 iu.ml-1 of hyaluronidase resulted in a mean (SEM) time to akinesia of 9.2 (0.9) min compared to 10.9 (0.9) min in the control group and 10.7 (1.1) min in those receiving the lower dose. Fewer patients in group C required a further injection (20%) than those in groups A (40%) or B (45%). None of the findings were statistically significant. Hyaluronidase was not associated with any complications.

Aged↗
PubMed1994

Mandibular form and position in 10-year-old boys.

It is unclear whether malocclusion characterized by jaw discrepancy is caused by variations in mandibular position, mandibular size, or a combination of the two. To clarify the situation, the mandibular outlines of 124 10-year-old boys, equally divided among the Angle classes, were generated from cephalograms with a computer plotting technique. The mean plots for each of the groups were superimposed on S-N and Go-Gn. These showed mandibular form and size to be similar in the Class I and Class III groups and in both divisions of Class II. The position of Class III mandibles was more anterior and rotated forward in relation to the cranial base compared with the other groups. Statistical analysis confirmed these findings. There was evidence to support the idea that Class II, Division 2 malocclusion is largely a dentoalveolar rather than a skeletal entity.

Cephalometry↗
PubMed1994

The effect of hyaluronidase on peribulbar block.

The effect of supplementing a standardised local anaesthetic mixture with hyaluronidase was studied in 60 patients undergoing peribulbar block for intra-ocular surgery. All the patients had the block performed with a 2:1 mixture of lignocaine 2% and bupivacaine 0.75%, but in half of the cases hyaluronidase 50 u.ml-1 was added to the solution by random allocation. The mean volumes of solution injected were 8.9 and 9.0 ml in the control and hyaluronidase groups respectively. Five minutes after injection the block was deemed unsuccessful in one third of the patients in each group and these patients required supplementary injections. At 15 min all but one patient in each group had satisfactory block and these two patients subsequently required retrobulbar block. There were no statistically significant differences between the two solutions in rate of onset of block, requirement for supplementation, block failure, or surgical conditions. There were no significant complications. We conclude that the addition of hyaluronidase 50 u.ml-1 to the local anaesthetic mixture described confers no advantage at the volumes of local anaesthetic used.

Aged↗
PubMed1993

Specialist postgraduate orthodontic training: a comparison of two European universities.

The background to current specialist training programmes in orthodontics in the United Kingdom and France is discussed, and the examination structure in the two countries compared with reference to those pertaining in Glasgow and Strasbourg. A sample of 40 of the most recently treated cases submitted by students in each of these two Universities for their final examinations is compared revealing marked differences in case type and treatment philosophy. The differences are explained, to some extent, by the circumstances pertaining to the delivery of orthodontic care in the two countries.

Adolescent↗
PubMed1993

Quantification of function regulator therapy using elliptical Fourier functions.

The application of various functional appliances to correct antero-posterior skeletal discrepancies in the treatment of Class III malocclusion has received increased attention. In this context, elliptical Fourier functions (EFF) are particularly useful for eliciting boundary-outline information. This longitudinal study was undertaken to visually and numerically describe the shape alterations arising as a response to treatment with the FR-3 appliance of Fränkel. The subjects chosen were Caucasians (n = 14) from the Glasgow Dental Hospital and School who presented with Class III incisor relationships. Lateral cephalometric head-films were available prior to the initiation of treatment, at the end of active treatment, and at least one year out of retention. Maxillary and mandibular boundary outlines were carefully traced. A set of points, 42 on the maxilla, and 78 on the mandible, were precisely located. These points were then digitized and used to compute EFF's with 20 harmonics. These equations were then standardized for size. Subsequently, 102 maxillary and 150 mandibular closely spaced points on the outline were calculated from the EFF's. After superimposition on the centroid, expected vectors were then computed to these points from the centroid. Statistically significant dento-alveolar shape changes could be discerned with treatment. These involved a localized anterior repositioning of the maxillary incisal aspect with a concomitant posterior displacement of the mandibular incisal aspect. There was no evidence of shape changes in the basal areas of either the maxilla or mandible. This method of fitting Fourier descriptors, specifically EFF's, provides a precise numerical and visual description of the changes arising from functional regulator therapy.

Adolescent↗
PubMed1993

Use of the PAR index in assessing the effectiveness of removable orthodontic appliances.

The dental study casts of 150 consecutively completed removable appliance cases were examined before and after orthodontic treatment using the PAR index. Eighty-nine per cent were classified either as 'improved' or 'greatly improved'. Of the 16 cases classified as 'worse, no different', six were mixed dentition cases with limited treatment objectives (which were successfully achieved) and three were permanent dentition cases where only one tooth was being aligned. Using predefined criteria removable appliances were shown to be most effective in treating cross-bites, ectopic tooth position, anterior spacing, and overjet, and less effective in treating crowding, rotations, and molar relationships.

Adolescent↗
PubMed1993

The general dental status of patients referred to the orthodontic department of the Glasgow Dental Hospital.

A survey of 280 orthodontic referrals to the Glasgow Dental Hospital, consecutively screened for orthodontic needs, revealed that 1 in 5 had untreated caries and more than half had a level of oral hygiene incompatible with wearing an orthodontic appliance. The suitability and motivation of such patients, therefore, must be questioned before prescribing orthodontic treatment.

Adolescent↗
PubMed1992

A new look at mandibular growth--a preliminary report.

Cephalometric radiographs of 42 growth study subjects (21 males, 21 females) were the basis of an investigation into the longitudinal growth of the mandible from 5 to 20 years using a digitizer program capable of generating curved outlines through groups of four points. In this presentation mean plots for all subjects at 5, 10, 15, and 20 years of age, variously superimposed, confirmed the previous theories of Björk and Skieller (1983) with regard to mandibular rotation and provide a visual representation of the processes of mandibular growth.

Adolescent↗
PubMed1992

A comparison of laryngeal mask airway with tracheal tube for intra-ocular ophthalmic surgery.

The use of the laryngeal mask was compared with tracheal intubation in 30 patients who underwent intra-ocular ophthalmic surgery and who received intravenous anaesthesia with propofol. Changes in intra-ocular pressure, heart rate and mean arterial pressure after the insertion of the laryngeal mask airway or the tracheal tube were not significantly different. However, at the end of the procedure, a significantly higher percentage of patients with a tracheal tube coughed, reacted to head movement and suffered breath-holding. In addition, significantly more patients in this group complained of a sore throat (p less than 0.05). During intravenous propofol anaesthesia, the laryngeal mask airway does not offer any advantage over tracheal intubation in the control of intra-ocular pressure for intra-ocular ophthalmic surgery. However, there were fewer complications immediately following surgery in the laryngeal mask group.

Anesthesia, Intravenous↗
PubMed1992

Class III malocclusion: surgery or orthodontics?

The pre-treatment lateral cephalograms of two groups of 20 subjects with severe Class III malocclusions were compared. One group had been considered suitable for orthodontic correction by the diagnosing clinician and the other offered orthognathic surgery. The most significant differences between the groups were in angle ANB, M/M ratio (P less than 0.001), lower incisor inclination and Holdaway angle (P less than 0.01). Threshold values for angle ANB and lower incisor angulation below which surgery was almost always carried out were--4 and 83 degrees, respectively.

Adolescent↗