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Biomedical subjects

A Petrie

Publications and source records attributed to A Petrie.

At least 19 recordsLinked to original sources
PubMed2006

Risk factors contributing to symptomatic plate removal following sagittal split osteotomy.

The records of 80 consecutive patients (160 plates) undergoing orthognathic surgery over a 2-year period were analysed to assess the percentage of plate removal from the mandible following sagittal split osteotomy. Factors considered in the study included age, sex, duration of operation, antibiotic prophylaxis regimen, general medical condition, smoking habits, mandibular moves, extraction of 3rd molars at time of surgery and the favourability of the mandibular splits. Infection was the sole reason for plate removal in this study. A removal rate of 15.6% was noted. Age and duration of operation were the only 2 statistically significant factors to affect plate removal whilst some of the other factors showed increased odds ratios but were not statistically significant.

Adolescent↗
PubMed2006

Duration, prevalence and intensity of bacteraemia after dental extractions in children.

OBJECTIVE: To investigate the duration, prevalence and intensity of bacteraemia after dental extractions in children by comparing within-patient bacteraemia before and after dental extraction. METHODS: Children were randomly allocated to one of 10 postprocedure time groups from 10 s to 60 min. The differences between intensity and prevalence of the bacteraemia at each time after extractions were used to estimate the duration of the bacteraemia. After attainment of general anaesthesia, pre-extraction and postextraction blood samples were processed by broth culture and lysis filtration to isolate and quantify bacteria present in the patients' blood. RESULTS: 500 subjects between 3 and 16 years old were recruited. The estimated duration of bacteraemia was about 11 min. CONCLUSIONS: The duration of bacteraemia after dental extractions is less than previously thought. This has implications for the interpretation of odontogenic bacteraemia studies.

Adolescent↗
PubMed2006

Statistics in orthopaedic papers.

Although the importance of sound statistical principles in the design and analysis of data has gained prominence in recent years, biostatistics, the application of statistics to the analysis of biological and medical data, is still a subject which is poorly understood and often mishandled. This review introduces, in the context of orthopaedic research, the terminology and the principles involved in simple data analysis, and outlines areas of medical statistics that have gained prominence in recent years. It also lists and provides an insight into some of the more common errors that occur in published orthopaedic journals and which are frequently encountered at the review stage in papers submitted to the Journal of Bone and Joint Surgery.

Biometry↗
PubMed2005

Effectiveness of alendronate and etidronate in the treatment of osteoporosis in men: a prospective observational study.

The prevalence of osteoporosis in men is higher than previously assumed; consequently, numerous therapies are being investigated to treat these patients. The Canadian Database of Osteoporosis and Osteopenia patients (CANDOO) was analyzed to examine changes in bone mineral density (BMD) in consecutively seen osteoporotic men administered alendronate, etidronate or no bone-active drugs (control) over 1 year. A total of 244 men attending six Canadian osteoporosis clinics were included in the study (42 alendronate, 102 etidronate and 100 control). Multiple imputation was used to model missing data to provide a more robust statistical model. The imputed datasets (five) were analyzed using multivariable linear regression to determine differences between groups in the percent change of lumbar spine (LS) and femoral neck (FN) BMD from baseline to 1 year. Differences in the percent change in BMD from baseline were most notable at the LS in favor of alendronate (4.3%; 95% CI: 2.1, 6.6 ) and etidronate (2.1%; 95% CI: 0.3, 4.0) therapy when compared with controls. At the LS, alendronate therapy led to significantly greater (2.2%; 95% CI: 0.2, 4.2) gains in BMD as compared to etidronate therapy. Compared to controls, there were no significant differences in FN BMD with alendronate (2.1%; 95% CI: -0.4, 4.7) or etidronate therapy (0.9%; 95% CI: -1.1, 2.8), nor were there significant differences between bisphosphonate groups (1.3%; 95% CI: -1.1, 3.6, in favor of alendronate). While both alendronate and etidronate significantly increased LS BMD in osteoporotic men after 1 year in real-world settings, alendronate therapy resulted in significantly superior gains in LS BMD. The effect of these two bisphosphonates on fractures and FN BMD in osteoporotic men is likely positive, but requires further study.

Alendronate↗
PubMed2005

The influence of self-deception and impression management upon self-assessment in oral surgery.

OBJECTIVE: To see if poor self-assessment of surgical performance during removal of mandibular third molars is influenced by self-deception (lack of insight) and impression management (trying to convey a favourable impression). DESIGN: A prospective study of 50 surgeons, surgically removing a lower third molar tooth. SETTING: One UK dental school over a two year period. METHODS: The surgeons' surgical skills were assessed (by two assessors) and self-assessed using check-list and global rating scales. Post-operatively, surgeons completed validated deception questionnaires which measured both self-deception enhancement (lack of insight), and impression management (the tendency to deliberately convey a favourable impression). MAIN OUTCOME MEASURES: Reliability between assessors, and between assessors' and surgeons' self-assessments were calculated. Discrepancies between assessors' and surgeons' scores were correlated with surgeons' deception scores. RESULTS: Reliability between assessors was excellent for checklist (0.96) and global rating scales (0.89) and better than the reliability between assessors and surgeons (0.51 and 0.49). There was a statistically significant correlation (r=0.45 p=0.001 checklist, r= 0.48 p<0.001 global) between over/ under-rating of their surgical performance by surgeons and their impression management scores. No statistically significant correlation was found between this inaccuracy in self-assessment and surgeons' individual self-deception scores. CONCLUSION: The majority of surgeons scored themselves higher than their assessors did for surgical skill in removing a single mandibular third molar tooth. Impression management (the tendency to deliberately convey a favourable impression) may contribute to a surgeon's inaccurate self-reporting of performance. Lack of insight appears to be much less important as a contributing factor. The authors speculate that pressure to provide evidence of good performance may be encouraging surgeons to manage their image and over-score themselves.

Attitude of Health Personnel↗
PubMed2005

Correlation between a patient-centred outcome score and surgical skill in oral surgery.

Our aim was to find out whether scores derived from a patient-centred outcome questionnaire correlated with the skill of the surgeon as assessed by a trainer. We found a relatively poor correlation after removal of a third mandibular molar, probably because outcome scores incorporate other measures, including patients' perceptions, anaesthesia, clarity of explanations and instructions, apart from surgical skill. The experience of the surgeon and the length of operation also influenced the results. The correlation was closest (i.e. higher levels of skill produced milder symptoms) when the operation was under local anaesthesia, probably because the surgeon's skill, behaviour, and attitude were visible to the patient throughout, and other team members had a less prominent role. In future, it may be more appropriate to assess the performance of the whole surgical team, rather than the surgeon alone.

Anesthesia, Dental↗
PubMed2005

Kinetics of Mx expression in rainbow trout (Oncorhynchus mykiss) and Atlantic salmon (Salmo salar L.) parr in response to VHS-DNA vaccination.

The duration of the Mx mRNA response to an intramuscular injection of the viral haemorrhagic septicaemia virus (VHSV) glycoprotein (G) gene DNA vaccine as well as to the control plasmid was determined in rainbow trout at 14 degrees C over a period of 11 weeks. The Mx response was detectable on day 7, peaked on day 14 and returned to pretreatment levels on day 21 and thereafter. No increase in Mx expression was detectable to the control plasmid. In further experiments, the kinetics of the Mx response were compared in rainbow trout and Atlantic salmon parr kept at 10 degrees C and injected with the DNA vaccine or the synthetic double-stranded RNA, poly I:C. In both species there was a rapid response to poly I:C detectable from day 1, reaching maximum from days 3 to 9 and decreasing to background level by day 12. The peak level and return to background was reached slightly later in salmon. In both species the response to the VHS/DNA vaccine was slower to begin, not being detectable on days 1 and 3, but elevated levels were found on day 6. However, in the salmon parr, the peak level was on day 6 and the signal disappeared by day 12, while in the rainbow trout, the response peaked at day 12 and lasted until day 21. The kinetics of the Mx response to the VHS/DNA vaccine in rainbow trout correlate with the early non-specific protection against VHS in this species following vaccination. It is speculated that the more transient Mx response in Atlantic salmon parr to the DNA vaccine may be related to the innate resistance of salmon to VHS.

Analysis of Variance↗
PubMed2005

Efficacy of removal of sucrose-supplemented interproximal plaque by electric toothbrushes in an in vitro model.

Electric toothbrushes were evaluated using a model of plaque removal by fluid shear forces. Sucrose supplementation during plaque development did not affect the removal of bacteria from biofilm exposed to low-energy shear but did increase their resistance to high-energy shear. The toothbrush supplying high-energy shear forces removed significantly more viable bacteria.

Bacteria↗
PubMed2004

Changes in transforming growth factor-beta1 in gingival crevicular fluid following periodontal surgery.

OBJECTIVES: Growth factors play a major part in wound healing, including in the periodontium. However, the presence of growth factors in gingival crevicular fluid (GCF) in humans during periodontal wound healing has not yet been determined. Our hypothesis is that such factors are present in GCF and that changes in their levels might be of value as a prognostic marker of wound-healing activity and therapeutic progress following periodontal surgery. The aim of this study was therefore to measure transforming growth factor-beta1 (TGF-beta1) in GCF collected from sites that have undergone guided tissue regeneration (GTR) and conventional flap (CF) surgery and to compare these with GCF collected from unaffected healthy sites. MATERIALS AND METHODS: GCF samples were collected, using filter paper strips, at baseline (pre-surgical) and then at intervals up to 26 weeks from 16 patients undergoing GTR and from 11 patients undergoing CF surgery. After elution and acid treatment, TGF-beta1 levels were measured by ELISA. RESULTS: Treatment of periodontal defect sites significantly reduced the mean probing pocket depth (PPD) and improved the mean lifetime cumulative attachment loss (LCAL). Average GCF volumes also significantly increased at all sites at 2 weeks post-surgery and thereafter declined to baseline levels, except at the GTR test sites that were still elevated at 7 weeks. TGF-beta1 could be detected in almost all GCF samples, and 2 weeks after surgery, the average levels increased two-fold at the surgically treated but not at the control sites, which remained unchanged. CONCLUSION: TGF-beta1 is readily detectable in GCF and increases transiently following periodontal surgery. This suggests that changes in the levels of this growth factor in GCF might be useful for monitoring the progress of periodontal repair and regeneration.

Adult↗
PubMed2003

Further statistics in dentistry. Part 9: Bayesian statistics.

Statistics can be defined as the methods used to assimilate data, so that guidance can be given, and conclusions drawn, in situations which involve uncertainty. In particular, statistical inference is concerned with drawing conclusions about particular aspects of a population when that population cannot be studied in full. Uncertainty arises here because the totality of the information is not available. Instead, to make inferences about the population, it is necessary to rely on a sample of data which is selected from the population; this sample data may be augmented, in certain circumstances, by auxiliary information which is obtained independently of the sample data. Clearly, uncertainty lies at the heart of statistics and statistical inference. This uncertainty is measured by a probability which therefore forms the crux of statistics and must be properly understood in order to interpret a statistical analysis.

Algorithms↗
PubMed2003

Further statistics in dentistry Part 8: Systematic reviews and meta-analyses.

A systematic review of research evidence is an efficient approach to integrating existing information, invariably a multiplicity of published articles, with a view to establishing whether the scientific findings are consistent. If so, it may be possible to draw conclusions and make recommendations about treatment regimens or observed effects which have greater credence than those obtained from individual studies. The systematic review relies on a specified checklist which determines which articles should be included in the review, and how each should be critically appraised to provide relevant information relating to the focus of the review.

Algorithms↗
PubMed2003

Further statistics in dentistry. Part 7: repeated measures.

Consider the situation in which there is a single quantitative variable of interest that is measured on each individual on several different occasions. Typically, these occasions are defined time points (usually including pre-treatment as well as various post-treatment times), so that each individual contributes a series of readings. The main objective of the study may be to compare the responses on this variable when each individual has been assigned to one of two or more treatments groups.

Analysis of Variance↗
PubMed2002

Further statistics in dentistry, Part 5: Diagnostic tests for oral conditions.

A diagnostic test is a simple test, sometimes based on a clinical measurement, which is used when the gold-standard test providing a definitive diagnosis of a given condition is too expensive, invasive or time-consuming to perform. The diagnostic test can be used to diagnose a dental condition in an individual patient or as a screening device in a population of apparently healthy individuals.

Costs and Cost Analysis↗
PubMed2002

Further statistics in dentistry. Part 4: Clinical trials 2.

The principles which underlie a well-designed clinical trial were introduced in a previous paper. The trial should be controlled (to ensure that the appropriate comparisons are made), randomised (to avoid allocation bias) and, preferably, blinded (to obviate assessment bias). However, taken in isolation, these concepts will not necessarily ensure that meaningful conclusions can be drawn from the study. It is essential that the sample size is large enough to enable the effects of interest to be estimated precisely, and to detect any real treatment differences.

Clinical Trials as Topic↗