Accuracy assessment of three‐dimensional surface reconstructions of teeth from Cone Beam Computed Tomography scans

Summary The use of three‐dimensional (3D) models of the dentition obtained from cone beam computed tomography (CBCT) is becoming increasingly more popular in dentistry. A recent trend is to replace the traditional dental casts with digital CBCT models for diagnosis, treatment planning and simulation. The accuracy of these models was previously assessed through comparing linear physical and radiographical measurements. However, this assessment technique is both observer and landmark dependent. The accuracy of 3D CBCT teeth reconstructions is yet to be reliably measured. To assess the accuracy of 3D CBCT reconstructions of the teeth using a semi‐automated and observer‐independent method and to assess the influence of field of view (FoV) selection on reconstruction accuracy. Fully dentate upper and lower dry human jaws, placed in a plastic box and immersed in water, were scanned using CBCT with small, medium and large FoV. The teeth were then scanned separately using MicroCT. Cone beam computed tomography and MicroCT 3D teeth models were compared, and mean surface difference was calculated per tooth for each FoV. Mean and (maximum) differences between MicroCT and CBCT were 120 ± 40 (max. 679) μm, 157 ± 39 (max. 824) μ and 207 ± 80 (max. 862) μm for the small, medium and large FoV, respectively. Cone beam computed tomography models were larger than MicroCT because of larger voxel size. Our results indicate that CBCT may provide accurate 3D reconstructions of the teeth that can be useful for some clinical applications.     

Midwives and Liability: Results from the 2009 Nationwide Survey of Certified Nurse‐Midwives and Certified Midwives in the United States

Introduction: In partnership with the American College of Nurse‐Midwives (ACNM), the authors conducted a survey of ACNM members to examine the incidence of lawsuit involvement, the outcomes of the litigation in which they were involved, and coping mechanisms among midwives who had been involved in a lawsuit. Methods: In the spring of 2009, a nationwide Web‐based survey was completed by ACNM members. In addition to using chi‐square tests and nonparametric testing in data analysis, a logistic regression model was used to evaluate predictors of lawsuit involvement. Results: Among 1340 midwives responding to the survey, 32% had been named in a lawsuit at least once. The median number of years in practice when the event leading to lawsuit occurred was 6. The majority of midwifery lawsuits involved hospital births and were settled prior to going to court. Three variables were statistically significant for involvement with litigation: the midwife's age, the number of births attended, and the ACNM region of practice in the United States. Discussion: Lawsuits among midwives were significantly related to exposure to births over time. Practice patterns and job security were not greatly affected by the experience of a lawsuit. Future cyclic surveys are needed to track the frequency of litigation and the outcomes that lead to lawsuits and to better define the relationships between midwifery practice and medical malpractice litigation.     

The link between major risk factors and important categories of admission in an ageing cohort

BACKGROUND: Record linkage of routine hospital data to population-based research findings presents an opportunity to explore the relationships between classical risk factors and hospital activity. METHODS: The objectives of this study were to examine, in Paisley and Renfrew, the effect of risk factor variables on the likelihood of experiencing an acute hospital admission with six major medical conditions. The subjects were 8,349 women and 7,057 men, aged 45-64 in the early to mid-1970s. The main outcome measures were acute hospital admission with principal diagnosis of: any malignant neoplasm; malignant neoplasm of trachea, bronchus and lung; ischaemic heart disease; respiratory disease; cerebrovascular disease; or diabetes mellitus. RESULTS: Smokers were almost eight times more likely to be admitted with lung cancer and, to a lesser extent, were more likely to be admitted for the other conditions investigated with the exception of diabetes mellitus. Forced expiratory volume was also an independent risk factor for admission with lung cancer and strokes. Higher levels of cholesterol were associated with increased risk of admission with ischaemic heart disease but less with cancer (including lung cancer). With the exception of admissions for cerebrovascular disease, deprivation category was found to have no independent effect on the likelihood of experiencing any of the morbidity outcomes examined. CONCLUSIONS: These data confirm that associations first established between risk factors and mortality outcomes (e.g. smoking and lung cancer) are also found between risk factors and hospital admissions for the same causes. This in itself is unremarkable, but the results are of interest for three reasons. First, they illustrate the potential of record linkage to map the effects of risk factors. Second, they demonstrate the size of the effect risk factors have on the risk of admission. Third, they provide a surprising finding that deprivation category does not act as an independent risk factor for the majority of the categories of admission investigated.     

Length polymorphism of heterochromatic segment of the Y chromosome in boys with acute leukemia

The extent of length polymorphisms of the heterochromatic and euchromatic segment of the human Y chromosome were investigated in 15 boys with acute leukemia and were compared with 15 normal controls. A greater value of the Yh/F index in relation to controls was established (P < 0.05). The length of the euchromatic segment was also shorter in the patients than the controls (P < 0.05).     

Effects on Plasma Glucose Concentration of Light-for-date Infants and Infants of Diabetic Mothers of Feeds Supplemented with a Glucose Polymer

ABSTRACT. Serial plasma glucose estimations were performed in 44 light-for-date infants and 17 infants of diabetic mothers fed 2, 3 or 4-hourly with feeds containing 10 % additional carbohydrate in the form of a glucose polymer (Caloreen). In the infants fed 2 and 3-hourly, plasma glucose was higher following the high carbohydrate feeds, particularly immediately before the next feed was due. Given 4-hourly, the high carbohydrate feed had little effect in most light-for-date infants, and in one light-for-date infant and two infants of diabetic mothers the plasma glucose was lower at the end of 4 hours than following normal formula. It is concluded that the addition of glucose polymer to feeds given 2 and 3 hourly has a potentially useful effect in neonates at risk of developing hypoglycaemia, but it cannot be used to increase the feed interval to 4 hours.     

Pharyngeal diverticula

A series of 73 hypopharyngeal (Zenker's) diverticula is reported and the choice of treatment and technique of excision are discussed. The problems of excision include operation on an infected site with limited access but few patients are unfit for the procedure. Preoperatively the sac should be packed and the oesophagus stented. The side of approach is unimportant as the condition is essentially midline. Cricopharyngeal myotomy appears to reduce the recurrence rate, possibly by improving coordination of pharyngeal contraction and upper oesophageal relaxation. The use of electrocoagulation is not recommended as 20% of patients require repeated general anaesthesia and the procedure fails in 13%. For all but the smallest pouches, excision is the treatment of choice.     

Protein kinase A hyperphosphorylation increases basal current but decreases beta-adrenergic responsiveness of the sarcolemmal Na+-Ca2+ exchanger in failing pig myocytes

The sodium-calcium exchanger (NCX) protein is the major cardiac calcium extrusion mechanism and is upregulated in heart failure (HF). NCX expression level and functional activity as regulated by beta-adrenergic receptor (beta-AR) stimulation in swine with and without tachycardia-induced heart failure were studied. The Ni2+-sensitive NCX current was measured in myocytes from HF and control animals in the basal state or in the presence of isoproterenol, forskolin, 8-Br-cAMP, okadaic acid, or protein phosphatase type 1. Western blot analysis revealed a significant increase in both the 120-kDa (29%) and 80-kDa (69%) fragments in HF (P<0.05 versus control). Despite this modest increase in protein, the basal peak outward NCX current was increased almost 5-fold in HF (P<0.05 versus control). Stimulation with isoproterenol, however, increased the control currents to a significantly greater extent than HF (500% increase in control versus 100% increase in HF, P<0.01); peak stimulated current was not different in HF and control. This reduction in responsiveness to beta-AR stimulation was refractory to forskolin, 8-Br-cAMP, or okadaic acid stimulation. In vitro protein kinase A back-phosphorylation revealed higher phosphorylation capacity of NCX protein in control versus HF, consistent with increased phosphorylation in vivo (hyperphosphorylation) in HF. Protein phosphatase type 1 exposure resulted in a significant reduction (73%) in peak basal current in HF (compared with no significant difference in controls), confirming that the increased basal NCX current in HF is predominantly attributable to hyperphosphorylation. NCX expression and activity are thus increased in HF, although beta-AR responsiveness is decreased because of NCX hyperphosphorylation.