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Biomedical subjects

Mike Stevenson

Publications and source records attributed to Mike Stevenson.

At least 19 recordsLinked to original sources
PubMed2007

A cephalometric study of Class II malocclusions treated with mandibular surgery.

INTRODUCTION: Class II malocclusion is often associated with retrognathic mandible. Some of these problems require surgical correction. The purposes of this study were to investigate treatment outcomes in patients with Class II malocclusions whose treatment included mandibular advancement surgery and to identify predictors of good outcomes. METHODS: Pretreatment and posttreatment cephalometric radiographs of 90 patients treated with mandibular advancement surgery by 57 consultant orthodontists in the United Kingdom before September 1998 were digitized, and cephalometric landmarks were identified. Paired samples t tests were used to compare the pretreatment and posttreatment cephalometric values for each patient. For each cephalometric variable, the proportion of patients falling within the ideal range was identified. Multiple logistic regression analysis was performed to identify predictors of achieving ideal range outcomes for the key skeletal (ANB and SNB angles), dental (overjet and overbite), and soft-tissue (Holdaway angle) measurements. RESULTS: An overjet within the ideal range of 1 to 4 mm was achieved in 72% of patients and was more likely with larger initial ANB angles. Horizontal correction of the incisor relationship was achieved by a combination of 75% skeletal movement and 25% dentoalveolar change. An ideal posttreatment ANB angle was achieved in 42% of patients and was more likely in females and those with larger pretreatment ANB angles. Ideal soft-tissue Holdaway angles (7 degrees to 14 degrees ) were achieved in 49% of patients and were more likely in females and those with smaller initial SNA angles. Mandibular incisor decompensation was incomplete in 28% of patients and was more likely in females and patients with greater pretreatment mandibular incisor proclination. Correction of increased overbite was generally successful, although anterior open bites were found in 16% of patients at the end of treatment. These patients were more likely to have had initial open bites. CONCLUSIONS: Mandibular surgery had a good success rate in normalizing the main dental and skeletal relationships. Less ideal soft-tissue profile outcomes were associated with larger pretreatment SNA-angle values, larger final mandibular incisor inclinations, and smaller final maxillary incisor inclinations. The use of mandibular surgery to correct anterior open bite was associated with poor outcomes.

Adolescent↗
PubMed2006

Class III surgical-orthodontic treatment: a cephalometric study.

INTRODUCTION: In this retrospective study, we investigated treatment outcomes in Class III surgical-orthodontic patients. METHODS: Records of 151 consecutively completed Class III surgical-orthodontic patients (overjet, 0 mm or less) were obtained from 87 consultant orthodontists in the United Kingdom. Pretreatment and posttreatment cephalometric radiographs were analyzed. RESULTS: Bimaxillary surgical patients (75%) had more negative initial ANB-angle values and smaller initial SNA-angle values than those treated with single-jaw mandibular surgery. Mandibular surgery patients (15%) had greater pretreatment mandibular prominence (SNB angle) than maxillary patients. Maxilla-only patients (10%) had lower negative initial overjet values than bimaxillary patients. An overjet within the ideal range of 1 to 4 mm was achieved in 83% of the patients. Logistic regression identified no predictors of ideal overjet outcome. SNB angle was corrected to within the ideal range of 75 degrees to 81 degrees in 44% of the patients. This was less likely in those treated with maxillary surgery only and larger initial SNB-angle values. An ideal posttreatment ANB angle (1 degrees to 5 degrees) was achieved in 40% of the patients and was more likely in those with bimaxillary surgery, lower negative pretreatment ANB angles, and presurgical orthodontic extractions in the maxillary arch. Ideal posttreatment unadjusted Holdaway angles (7 degrees to 14 degrees) were achieved in 59% of the patients and were more likely when single-jaw mandibular surgery was used. Incisor decompensation was incomplete in 46% of the patients and was associated with mandibular arch extractions. CONCLUSIONS: Surgical-orthodontic treatment had a high success rate in normalizing the overjet and soft-tissue profile to within ideal ranges in Class III patients. Bimaxillary surgery was the most frequently used procedure and was associated with an increased likelihood of an ideal correction of the anteroposterior skeletal discrepancy.

Adolescent↗
PubMed2006

Combined antioxidant therapy reduces pain and improves quality of life in chronic pancreatitis.

Patients with chronic pancreatitis (CP) typically suffer intractable abdominal pain that is resistant to most analgesic strategies. Recent research indicates that the pain of CP may be in part due to oxygen free radical induced pancreatic damage. Using a randomized, double-blind, placebo-controlled crossover trial, we evaluated the efficacy of a combined antioxidant preparation in the management of CP. Patients with confirmed chronic pancreatitis (N = 36) were randomized to receive treatment with either Antox, which contains the antioxidants selenium, betacarotene, L-methionine, and vitamins C and E, or placebo for 10 weeks. Each group of patients then switched to receive the alternative treatment for a further 10 weeks. Markers of antioxidant status were measured by blood sampling, whereas quality of life and pain were assessed using the SF-36 questionnaire. Nineteen patients completed the full 20 weeks of treatment. Treatment with Antox was associated with significant improvements in quality of life in terms of pain (+17 antioxidant vs. -7 placebo), physical (+9 vs. -3) and social functioning (+8 vs. -7), and general health perception (+10 vs. -3). We conclude that treatment with antioxidants may improve quality of life and reduce pain in patients suffering from chronic pancreatitis.

Abdominal Pain↗
PubMed2006

An investigation of weak syllable processing in deaf children with cochlear implants.

In this study the influence of prosodic foot structure on the processing of weak syllables in children with cochlear implants (CI) was investigated. A battery of tests investigating processing of weak syllables in single and multi-word utterances was carried out on four groups of children: 15 children with CI developing spoken language as expected (Main CI); five children with CI reported to have additional speech and language problems; 15 age matched; and 15 language matched (LM) children with normal hearing (NH). Children in the main CI and, to a lesser extent, the LM groups processed footed weak syllables preferably over unfooted weak syllables (particularly as memory load increased). Thus, these children with CI appear to possess a similar Prosodic Hierarchy (PH) to their LM peers with NH, and possibly due to the impact of delayed and constrained exposure to audition on the development of linguistic processing and short-term memory, are influenced by its foot structure in the processing of weak syllables.

Analysis of Variance↗
PubMed2006

Novel rectangular biphasic and monophasic waveforms delivered by a radiofrequency-powered defibrillator compared with conventional capacitor-based waveforms in transvenous cardioversion of atrial fibrillation.

AIMS: To investigate the feasibility and efficacy of novel low-tilt biphasic waveforms in transvenous cardioversion of atrial fibrillation (AF), delivered by a radiofrequency-powered defibrillator. METHODS AND RESULTS: The investigation was performed in three phases in an animal model of AF: a feasibility and efficacy study (in 10 adult Large White Landrace swine), comparison with low-tilt monophasic and standard capacitor-based waveforms, and an assessment of sequential shocks delivered over several pathways (in 15 adult Suffolk sheep). Defibrillation electrodes were positioned transvenously under fluoroscopic control in the high lateral right atrium and distal coronary sinus. When multiple defibrillation pathways were tested, a third electrode was also attached to the lower interatrial septum. The electrodes were then connected to a radiofrequency (RF)-powered defibrillator or a standard defibrillator. After confirmation of successful induction of sustained AF, defibrillation was attempted. Percentage success was calculated from the effects of all shocks delivered to all the animals within each set of experiments. Of the low-tilt (RF) biphasic waveforms delivered during internal atrial cardioversion, 100% success was achieved with a 6/6 ms 100/-50 V waveform (1.45+/-0.01 J). This waveform was similar in efficacy to low-tilt (RF) monophasic waveforms (88 vs. 92% success, 1.58+/-0.01 vs. 2.67+/-0.03 J; P=NS; delivered energy 41% lower) and superior to equivalent voltage standard monophasic (50% success, 0.67+/-0.00 J; P<0.001) and biphasic waveforms (72% success, 0.69+/-0.00 J; P=0.03). Sequential shocks delivered over dual pathways did not improve the efficacy of low-tilt biphasic waveforms. CONCLUSION: A low-tilt biphasic waveform from a RF-powered defibrillator (6/6 ms 100/-50 V) is more efficacious than standard monophasic or biphasic waveforms (equivalent voltage) and is similar in efficacy to low-tilt monophasic waveforms.

Animals↗
PubMed2006

Self-reports of psychosocial functioning among children and young adults with cleft lip and palate.

OBJECTIVE: A cross-sectional study was employed to determine the psychosocial effects of cleft lip and/or palate among children and young adults, compared with a control group of children and young adults without cleft lip and palate. PARTICIPANTS: The study comprised 160 children and young adults with cleft lip and/or palate and 113 children and young adults without cleft lip and/or palate. All participants were between 8 and 21 years of age. OUTCOME MEASURES: Psychological functioning (anxiety, self-esteem, depression, and behavioral problems) was assessed using validated psychological questionnaires. Happiness with facial appearance was rated using a visual analog scale. Social functioning, including experience of teasing/bullying and satisfaction with speech, was assessed using a semistructured interview. RESULTS: Participants with cleft lip and/or palate reported greater behavioral problems (p < .001) and more symptoms of depression (p < .01); they were teased more often (p < .001) and were less happy with their facial appearance (p < .01) and speech (p < .001), compared with controls. There were no significant difference between subjects with cleft lip and/or palate and subjects without cleft lip and/or palate in terms of anxiety (p > .05) or self-esteem (p > .05). Having been teased was a significant predictor of poor psychological functioning, more so than having a cleft lip and/or palate per se (p < .001). CONCLUSIONS: Teasing was greater among participants who had cleft lip and/ or palate and it was a significant predictor of poorer psychosocial functioning. Children and young adults with cleft lip and/or palate require psychological assessment, specifically focusing on their experience of teasing, as part of their routine cleft care.

Adolescent↗
PubMed2005

Impedance compensated biphasic waveforms for transthoracic cardioversion of atrial fibrillation: a multi-centre comparison of antero-apical and antero-posterior pad positions.

AIMS: To compare the success rate for transthoracic direct current cardioversion (DCC) of atrial fibrillation (AF) with antero-posterior (AP) and antero-apical (AA) electrode positions using an impedance compensated biphasic (ICB) waveform. METHODS AND RESULTS: Three-hundred and seven patients [mean age 66 (SD+/-13), 195 male] with AF were recruited in three centres. Patients were randomized to an AA (n=150) or AP (n=144) pad position. Thirteen patients with implanted pacemakers were defaulted to the AP pad position. Cardioversion was performed using an ICB waveform with a 70, 100, 150, and 200 J energy selection protocol. If the fourth shock was unsuccessful, the pads were crossed over to the alternative position for a final 200 J shock. Shock 1 was successful in 54/150 (36%) AA and 45/144 (31%) AP patients, whereas success was achieved by shock 2 in 99/150 (66%) AA and 74/144 (51%) AP, by shock 3 in 123/150 (82%) AA and 109/144 (76%) AP, and by shock 4 in 143/150 (95%) AA and 127/144 (88%) AP and after cross-over in 144/150 (96%) AA and 135/144 (94%) AP. Overall success rate was higher than expected at 95%. Pad position was not associated significantly with success. There was a trend towards an improved outcome with the AA configuration (P=0.05). CONCLUSION: The influence of pad position for DCC of AF may be less pertinent with ICB waveforms than with monophasic waveforms.

Aged↗
PubMed2005

Percutaneous coronary intervention and 1 year survival in patients treated with fibrinolytic therapy for acute ST-elevation myocardial infarction.

AIMS: To assess the predictors of 1 year mortality in patients treated with fibrinolytic therapy for ST-segment elevation myocardial infarction (STEMI) and to determine whether a strategy of early percutaneous coronary intervention (PCI) improves outcome. METHODS AND RESULTS: Consecutive patients (n = 474) admitted to our unit (1998-2001) with STEMI were treated with fibrinolytic therapy. For each patient, age, gender, admission via mobile coronary care unit (MCCU), infarct location, initial systolic blood pressure and Killip class, prior history of ischaemic heart disease, hypertension, diabetes mellitus, smoking status, family history, hyperlipidaemia, and in-hospital PCI (n = 154) were recorded. Mortality at 1 year was obtained from medical records (n = 473). Binary logistic regression analysis was performed to determine independent predictors of 1 year mortality. Mortality in the non-PCI group was 21 vs. 7% in the PCI group. Independent predictors of 1 year mortality were age (risk ratio 1.12, 95% CI 1.08-1.15, P < 0.0001), initial SBP < or = 80 mmHg (risk ratio 4.34, 95% CI 1.68-11.2, P = 0.002), initial Killip class > or = 3 (risk ratio 2.97, 95% CI 1.42-6.2, P = 0.004), and lack of in-hospital PCI (risk ratio 0.39, 95% CI 0.19-0.81, P = 0.012). Although the PCI group were younger (P = 0.007), more likely to be admitted via the MCCU (P = 0.008), with a shorter pain to needle time (P = 0.04), multivariable analysis adjusted for these differences. CONCLUSION: In-hospital PCI in patients treated with fibrinolytic therapy for STEMI is associated with a substantial reduction in 1 year mortality.

Aged↗
PubMed2005

The influence of mandibular prominence on facial attractiveness.

This study examined the attractiveness of facial profiles. One hundred and two social science students (28 males and 74 females) rated the attractiveness of a series of silhouettes with normal, Class II or Class III profiles. A random sequence of 10 images included an image with the Eastman normal SNB value of 78 degrees, and images with SNB values of 2.5, 5, 7.5 and 10 degrees above and below normal. A duplicate image in each sequence was used to assess reproducibility. The participants scored the attractiveness of each image and also indicated whether they would seek treatment if each image was their own profile. The profile with the normal SNB angle of 78 degrees was rated as the most attractive. Attractiveness scores reduced as the mandibular profile diverged from the normal SNB value. The +5 degree profile (SNB = 83 degrees) was rated as significantly more attractive than the -5 degree profile (SNB = 73 degrees; P = 0.004). No other significant differences between the scores for Class II and Class III profile pairs of equal severity were found. At 10 degrees below the normal SNB (Class II), 74 per cent of the sample would elect to have treatment, while 78 per cent would elect to have treatment at 10 degrees above the normal SNB (Class III).

Adolescent↗
PubMed2004

The prevalence of bacteraemia on removal of fixed orthodontic appliances.

This study investigated the prevalence of bacteraemia on removal of fixed appliances. Venous blood samples were taken before and after debonding and debanding for 30 patients (mean age 17 years 8 months) who had worn fixed appliances for an average of 19 months. Before removal of the fixed appliances, bacteraemia was detected in one of the 30 subjects (3%) and in four subjects (13%) following removal of their fixed appliances. The 95 per cent confidence intervals for the prevalence of post-debanding bacteraemia were 3.8 and 30.7 per cent. No significant relationship was detected between the mean plaque scores (t = -0.65, P = 0.52) or the mean gingival scores (t = 0.75, P = 0.46) and the occurrence of bacteraemia. The prevalence of bacteraemia detected following debanding in this study is considerably lower than reported for dental procedures traditionally covered by antibiotic prophylaxis guidelines.

Actinomyces↗
PubMed2004

Are data on the uptake of disability benefits a useful addition to census data in describing population health care needs?

OBJECTIVE: To determine if administrative data relating to the uptake of disability benefits held by government departments in Northern Ireland are fair and unbiased indicators of relative need for health care and therefore a useful addition to census data. METHOD: This is an ecological study of the 566 electoral wards in Northern Ireland. The variation in uptake of a health-related benefit (Disability Living Allowance) was regressed against three other indicators of health (limiting long-term illness, mortality and the numbers of patients admitted to hospital). All the indicators had been indirectly standardised by age and sex. The unstandardised residuals from this model were regressed against the social and geographical factors, namely area deprivation score, religious denominational composition and urban/rural dwelling to see if they influenced benefit uptake above and beyond any association with ill health. RESULTS: The health factors alone explained 77.2% of the variation in benefit uptake, with limiting long-term illness being the major determinant; however, even after controlling for differences in health status, benefit uptake was shown to be higher in more urban areas and in areas that had a greater proportion of Catholics. Area deprivation was not associated with benefit uptake once health differences had been controlled for. CONCLUSION: Administrative data on disability benefits can undoubtedly provide useful additional information for describing the levels of relative disadvantage or ill health of areas. However, because they also reflect variations in uptake, which appears to be confounded by social and geographical factors, we would urge caution when they are used to identify priority areas or to allocate resources.

Adult↗
PubMed2004

Equity of use of inpatient services by the two communities in Northern Ireland.

OBJECTIVE: There is concern about whether public services in Northern Ireland are equitably targeted across the religious divide. This study investigates whether use of acute hospital inpatient services differs by religious denomination, after adjusting for supply and for identified demographic, morbidity and socio-economic determinants of need for such services. METHODS: Hospital utilisation at small area level was modelled against a wide range of potential health and socioeconomic factors. Spatial interactive modelling was used to estimate the effect of supply of hospital beds and other facilities on hospital utilisation. Two-stage weighted least-squares regression was used to model utilisation against need and supply. RESULTS: There was a clear positive relationship between the proportion of Roman Catholics in a ward and both need for and utilisation of inpatient services. The higher levels of relative utilisation in wards with a greater proportion of Catholics persisted after controlling for needs but not when supply variables were also entered in the regression equation. The surviving needs drivers were: uptake levels of 'income maintenance' benefits, all-ages standardised mortality ratio, low birth weight and elderly people living alone. Most of these indicators of need are positively correlated with proportion of Catholics. CONCLUSIONS: When both need and supply factors are taken into account, there appears to be no significant effect of religion on inpatient hospital use in Northern Ireland. Efforts to ensure socio-economic equity between the two communities should focus on ensuring that hospital rationalisation does not lead to disadvantage and on reducing socio-economic differentials between the Catholic and Protestant communities.

Catchment Area, Health↗
PubMed2003

Antidepressant prescribing and suicide rate in Northern Ireland.

PURPOSE: Although antidepressants are the most commonly used treatment for depressive illness, there is uncertainty if their use is associated with a reduction in suicide rate. Antidepressant prescribing in Northern Ireland has increased over fivefold in the decade 1989-1999. The authors sought to explore whether this increase was associated with a reduction in suicide rate taking into account social and political factors thought also to have an influence on suicide. MATERIALS AND METHODS: Factors that have been suggested to influence suicide were entered into a linear regression with frequency of suicide and undetermined deaths (referred to as suicide rate) as the dependent variable. The above factors were antidepressant prescribing, unemployment rate, household alcohol expenditure and persons charged with terrorist offences. The rise in younger suicides, in recent decades, suggests this analysis should be carried out separately for younger (less than 30 years) and older (30 years and above) suicides separately. The predictors in the two models are based on aggregate data for the total group. RESULT: In the younger group there was no association between antidepressant prescribing and suicide. For the older group increased antidepressant prescribing was associated with a reduction in suicide rate over the 10 years of the study. CONCLUSION: Increasing antidepressant prescribing appears to be an effective strategy for reducing suicide. This has been demonstrated in older individuals.

Adult↗
PubMed2003

Photo-elastic stress analysis of initial alignment archwires.

Photo-elastic models replicating a lower arch with a moderate degree of lower incisor crowding and a palatally displaced maxillary canine were used to evaluate the stresses transmitted to the roots of the teeth by initial alignment archwires. Six initial alignment archwires were compared, two multi-strand stainless steel wires, two non-super-elastic (stabilized martensitic form) nickel titanium wires, and two stress-induced super-elastic (austenitic active) nickel titanium wires. Three specimens of each archwire type were tested. Analysis of the photo-elastic fringe patterns, in the medium supporting the teeth, revealed that the non-super-elastic nickel titanium archwires produced the highest shear stresses (P = 0.001). However, the shear stresses generated by the super-elastic alignment archwires and the multi-strand stainless steel archwires were very similar (P = 1.00). These results show that even in situations where large deflections of initial alignment archwires are required, super-elastic archwires do not appear to have any marked advantage over multi-strand stainless steel alignment archwires in terms of the stresses transferred to the roots of the teeth.

Analysis of Variance↗
PubMed2003

Localizing ectopic maxillary canines--horizontal or vertical parallax?

This study compared the use of horizontal parallax (HP) and vertical parallax (VP) radiography for localizing ectopic maxillary canines (EMCs). The true positions of 43 EMCs were determined using the operative notes and subsequent study models following exposure and eruption. Thirty-four palatal and nine buccal EMCs were included in the study. Six experienced orthodontists examined the radiographs of the EMCs and were asked to localize each EMC using VP and HP on separate occasions. The examiners recorded a diagnosis of 'unsure' in 12 per cent of cases using VP and in 5 per cent of cases using HP. The level of agreement of the diagnoses with the true position of the EMCs was significantly greater for HP. Eighty-three per cent of EMCs were correctly located with HP while only 68 per cent were correctly located with VP (P < 0.05). The diagnostic sensitivity for palatally placed canines was significantly greater for HP (88 per cent) than for VP (69 per cent). Both techniques performed poorly when used to localize buccal EMCs, with HP and VP each having a sensitivity of only 63 per cent. It is concluded that HP is superior to VP in diagnostic accuracy, and that two peri-apical radiographs or one peri-apical and one anterior occlusal radiograph are the radiographs of choice for localizing EMCs.

Adolescent↗
PubMed2002

The Aesthetic Component of the Index of Orthodontic Treatment Need validated against lay opinion.

This study aimed to determine the threshold of aesthetic impairment where orthodontic treatment would be sought by a sample of lay people. Using the 10-grade Aesthetic Component (AC) scale of the Index of Orthodontic Treatment Need (IOTN), 215 university students selected the level of aesthetic impairment that represented the point at which they would seek orthodontic treatment. Only nine (4.3 per cent) of the respondents recorded a threshold grade beyond grade 5 in the AC. The AC photograph grade 4 was found to be the most commonly selected threshold photograph. Subjects who visited the dentist every 6 months were more likely to choose a threshold photograph closer to the attractive end of the scale than those who visited their dentist less frequently (P < 0.01). This study, using lay people rather than dental health professionals, suggests that as currently used the AC does not reflect society's aesthetic expectations. The results indicate that when using the AC of the IOTN the 'no need for treatment' category should be grades 1-3 of the AC, rather than grades 1-4.

Adolescent↗
PubMed2002

The influence of maxillary gingival exposure on dental attractiveness ratings.

This study examined the influence of maxillary gingival display on the attractiveness ratings awarded by lay people. One hundred and twenty university students (94 females, 26 males) were shown seven photographs of a male and seven photographs of a female subject, each with varying levels of gingival display ranging from -2 to +4 mm. Attractiveness ratings were recorded on a 10-point numerical scale for each of the photographs. The photographs where the full height of the incisors were revealed and no gingival tissue was visible (0 mm of gingiva) were rated as the most attractive. Gingival display of more than 2 mm was rated as progressively less attractive. Linear regression analysis revealed that those students who had received orthodontic treatment rated the photographs representing the female student as more attractive than those representing the male (P < 0.05).

Adult↗