A Pragmatic Bayesian Perspective on Correlation Analysis : The exoplanetary gravity - stellar activity case.

We apply the Bayesian framework to assess the presence of a correlation between two quantities. To do so, we estimate the probability distribution of the parameter of interest, ρ, characterizing the strength of the correlation. We provide an implementation of these ideas and concepts using python programming language and the pyMC module in a very short (∼ 130 lines of code, heavily commented) and user-friendly program. We used this tool to assess the presence and properties of the correlation between planetary surface gravity and stellar activity level as measured by the log([Formula: see text]) indicator. The results of the Bayesian analysis are qualitatively similar to those obtained via p-value analysis, and support the presence of a correlation in the data. The results are more robust in their derivation and more informative, revealing interesting features such as asymmetric posterior distributions or markedly different credible intervals, and allowing for a deeper exploration. We encourage the reader interested in this kind of problem to apply our code to his/her own scientific problems. The full understanding of what the Bayesian framework is can only be gained through the insight that comes by handling priors, assessing the convergence of Monte Carlo runs, and a multitude of other practical problems. We hope to contribute so that Bayesian analysis becomes a tool in the toolkit of researchers, and they understand by experience its advantages and limitations.

Assessment of the changes in quality of life of patients with class II and III deformities during and after orthodontic-surgical treatment.

The aim of this longitudinal study was to assess and compare the oral health-related quality of life (OHRQoL) of patients with class II and III deformities during and after orthodontic-surgical treatment. Thirty class III and 28 class II patients were evaluated at baseline (T0), just prior to surgery (T1), at 6 months after surgery (T2), and at 12 months after debonding (T3). OHRQoL was assessed using the Oral Health Impact Profile (OHIP-14). Friedman two-way analysis of variance and the Wilcoxon signed-rank test were performed to compare the relative changes in OHRQoL during treatment. Significant changes in the overall OHIP-14 scores were observed during and after orthodontic-surgical treatment in both groups. During the pre-surgical stage, psychological discomfort and psychological disability decreased in class III patients, and class II patients experienced a significant deterioration in psychological discomfort during the same period. Six months after surgery, patients in both groups showed improvements in psychological discomfort, social disability, and handicap. Physical disability and functional limitation showed further improvement at 12 months after debonding in class II patients. This study reaffirms that orthodontic-surgical treatment has a significant effect on the OHRQoL of class III and class II patients.

Effects of image enhancement on reliability of landmark identification in digital cephalometry.

INTRODUCTION: Although digital cephalometric radiography is gaining popularity in orthodontic practice, the most important source of error in its tracing is uncertainty in landmark identification. Therefore, efforts to improve accuracy in landmark identification were directed primarily toward the improvement in image quality. One of the more useful techniques of this process involves digital image enhancement which can increase overall visual quality of image, but this does not necessarily mean a better identification of landmarks. The purpose of this study was to evaluate the effectiveness of digital image enhancements on reliability of landmark identification. MATERIALS AND METHODS: Fifteen common landmarks including 10 skeletal and 5 soft tissues were selected on the cephalograms of 20 randomly selected patients, prepared in Natural Head Position (NHP). Two observers (orthodontists) identified landmarks on the 20 original photostimulable phosphor (PSP) digital cephalogram images and 20 enhanced digital images twice with an intervening time interval of at least 4 weeks. The x and y coordinates were further analyzed to evaluate the pattern of recording differences in horizontal and vertical directions. Reliability of landmarks identification was analyzed by paired t test. RESULTS: There was a significant difference between original and enhanced digital images in terms of reliability of points Ar and N in vertical and horizontal dimensions, and enhanced images were significantly more reliable than original images. Identification of A point, Pogonion and Pronasal points, in vertical dimension of enhanced images was significantly more reliable than original ones. Reliability of Menton point identification in horizontal dimension was significantly more in enhanced images than original ones. CONCLUSION: Direct digital image enhancement by altering brightness and contrast can increase reliability of some landmark identification and this may lead to more accurate cephalometric analysis.

Accuracy of computerized automatic identification of cephalometric landmarks by a designed software.

OBJECTIVES: The purpose of this study was to design software for localization of cephalometric landmarks and to evaluate its accuracy in finding landmarks. METHODS: 40 digital cephalometric radiographs were randomly selected. 16 landmarks which were important in most cephalometric analyses were chosen to be identified. Three expert orthodontists manually identified landmarks twice. The mean of two measurements of each landmark was defined as the baseline landmark. The computer was then able to compare the automatic system's estimate of a landmark with the baseline landmark. The software was designed using Delphi and Matlab programming languages. The techniques were template matching, edge enhancement and some accessory techniques. RESULTS: The total mean error between manually identified and automatically identified landmarks was 2.59 mm. 12.5% of landmarks had mean errors less than 1 mm. 43.75% of landmarks had mean errors less than 2 mm. The mean errors of all landmarks except the anterior nasal spine were less than 4 mm. CONCLUSIONS: This software had significant accuracy for localization of cephalometric landmarks and could be used in future applications. It seems that the accuracy obtained with the software which was developed in this study is better than previous automated systems that have used model-based and knowledge-based approaches.

Awareness of Iranian's General Dentists Regarding the Latest Prophylaxis Guideline for Prevention of Infective Endocarditis.

UNLABELLED: Statement of Problem : Dental procedures leading to oral tissue injuries may provoke bacterial release to the blood stream causing infective endocarditis (IE) in vulnerable patients. The guideline which was proposed by AHA has been updated 9 times having the last update published in 2007. This study was endeavored to uncover the level of knowledge of general dental practitioners in Shiraz, concerning the 2007 AHA guidelines for endocarditis prophylaxis in patients with cardiac problems receiving dental treatments. MATERIALS AND METHOD: This cross- sectional and descriptive analytical study included 150 dentists as participants. All practitioners were given a self -report questionnaire which consisted of three sections. Questions were designed to assess their knowledge of antibiotic prophylaxis in patients with cardiac disease. RESULTS: Almost all participants (93%) were aware of antibiotic prophylaxis to be essential for tooth extraction. Most participants did not believe in prophylaxis for noninvasive procedures (such as shedding of primary teeth, impression, intraoral radiography). From all of the respondents, 75% considered Amoxicillin to be the antibiotic of choice and 57% were acquainted with the correct dose of Amoxicillin for high risk patients. CONCLUSION: The study identified a potential for under/over prescription of antibiotic prophylaxis under the current guideline. Burden of IE necessitates more accurate knowledge of antibiotic prophylaxis in the undergraduate curriculum and continuing education programs of dentistry.

A Comparison of pical Root Resorption in Incisors after Fixed Orthodontic Treatment with Standard Edgewise and Straight Wire (MBT) Method.

STATEMENT OF PROBLEM: One of the major outcomes of orthodontic treatment is the apical root resorption of teeth moved during the treatment. Identifying the possible risk factors, are necessary for every orthodontist. PURPOSE: The aim of this study was to compare the rate of apical root resorption after fixed orthodontic treatment with standard edgewise and straight wire (MBT) method, and also to evaluate other factors effecting the rate of root resorption in orthodontic treatments. MATERIALS AND METHOD: In this study, parallel periapical radiographs of 127 patients imaging a total of 737 individual teeth, were collected. A total of 76 patients were treated by standard edgewise and 51 patients by straight wire method. The periapical radiographs were scanned and then the percentage of root resorption was calculated by Photoshop software. The data were analyzed by Paired-Samples t-test and the Generalized Linear Model adopting the SPSS 15.0. RESULTS: In patients treated with straight wire method (MBT), mean root resorption was 18.26% compared to 14.82% in patients treated with standard edgewise technique (p< .05). Male patients had higher rate of root resorption,statistically significant (p< .05). Age at onset of treatment, duration of treatment, type of dental occlusion, premolar extractions and the use of intermaxillary elastics had no significant effect on the root resorption in this study. CONCLUSION: Having more root resorption in the straight wire method and less in the standard edgewise technique can be attributed to more root movement in pre-adjusted MBT technique due to the brackets employed in this method.

Effect of Recycling and Autoclave Sterilization on the Unloading Forces of NiTi Closed-Coil Springs: An In Vitro Study.

STATEMENT OF PROBLEM: Clinicians use the NiTi coil springs frequently for its appropriate mechanical properties. PURPOSE: The aim of this study was to determine the effect of recycling and autoclave sterilization on the unloading forces of NiTi closed coil springs. MATERIALS AND METHOD: Fourteen NiTi closed coil spring with the length of 9mm were selected. Each coil was stretched to a peak extension of 12 mm. A universal testing machine was used to acquire load/deflection curve of the coil springs at 25±2°C. The influence of thermocycling (1000 cycles,5-55°C), autoclaving (134°C, 32PSI, 3min) and mechanical strain (9mm extension) which simulated the oral condition, were considered. Data were statistically analyzed by adopting Repeated Measures MANOVA Paired t-Test. RESULTS: Autoclaving in the 1, 4, 6 steps increased the force levels of coil springs about 2-5gf (p< 0.01). Thermocycling reduced their force levels about 4-6gf. Prolonged strain at 3, 5 steps decreased the magnitude of forces levels about 3-4gf. CONCLUSION: Concerning all the limitations; according to the results of this study; it is possible to recycle Ni-Ti closed-coil springs without significant reduction in their force levels.

Autoclaving and clinical recycling: effects on mechanical properties of orthodontic wires.

BACKGROUND: About half of the orthodontists recycle and reuse orthodontic wires because of their costs. So when talking about reuse and sterilization of wires, their effects on mechanical properties of wires should be clarified. The purpose of this study was to assess the effects of sterilization and clinical use on mechanical properties of stainless steel wires. MATERIALS AND METHODS: Thirty stainless steel orthodontic wires were divided into three equal groups of control, autoclave (sterilized by autoclave), and recycle group (wires were used for orthodontic patients up to 4 weeks, cleaned by isopropyl alcohol and sterilized by autoclave). The mechanical properties (tensile test, three-point loading test for load-deflection curve) were determined. RESULTS: Fracture force, yield strength, stiffness and modulus of elasticity in recycle groups were significantly lower than the other groups (P < 0.05). CONCLUSION: Although recycle wires were softer than those of control group, relatively small differences and also various properties of available wires have obscured the clinical predictability of their application. There is seemingly no problem in terms of mechanical properties to recycle orthodontic wires.

Prevalence of malocclusions in school-age children attending the orthodontics department of Shiraz University of Medical Sciences.

To provide quantitative data about the prevalence of malocclusions in the Shiraz orthodontic population, we studied the records of 700 patients (391 girls and 309 boys) aged 6-14 years attending the undergraduate Department of Orthodontics at Shiraz University of Medical Sciences. The prevalence of Angle class I, II and III malocclusion of first molars was 52.0%, 32.6% and 12.3% respectively. Skeletal class I, II and III malocclusion was found in 18.0%, 70.0% and 12.0% respectively. There were no significant differences between the sexes in the prevalence of different types of skeletal malocclusion. Children with class III were significantly younger (mean age 8.9 years) than those with class I (9.6 years) or class II (9.7 years) malocclusions. Orthodontics students need more education and training in the management of class II malocclusion to improve the overall quality of care for patients.

Assessment of parental awareness about malocclusion in Shiraz, Islamic Republic of Iran.

Information empowers people to take charge of their health. The aim of this study in Shiraz, Islamic Republic of Iran was to evaluate parents' knowledge about dental malocclusion, referral routes and information sources. A random sample of 1000 7-9-year-old schoolchildren were given a questionnaire to complete at home. Questionnaires were completed by 795 parents. Knowledge about malocclusion was significantly greater in families with higher levels of education and income. Most respondents (83.5%) were aware of the importance of maintaining primary teeth to prevent malocclusion, and 25.1% thought that carious primary teeth must be extracted. Half of the parents (50.6%) did not know that spaces between primary teeth are normal. Only 28.8% of the children visited dentists for annual routine check-ups. Television (43.3%) was the most common source of dental information. The level of general public awareness about malocclusion needs to be improved.

Impact of an educational leaflet on parents' knowledge and awareness of children's orthodontic problems in Shiraz.

ABSTRACT Raising parents' awareness about dentofacial malocclusions is important for avoiding delays in seeking treatment. The aim of the present research was to assess the impact of an educational leaflet on parent's knowledge and awareness of orthodontic malocclusion in children. Parents of 533 7-9-year-old schoolchildren were randomized into a leaflet group who received an educational leaflet and a control group with no leaflet. Pre-and post-intervention test scores on a questionnaire about orthodontic problems were compared. Differences between post- and pre-test scores were significantly higher in the leaflet group than the control group for the total score and the domain on general awareness of orthodontic problems. Scores on the domain of knowledge of referral intervals did not differ significantly. Information leaflets may be useful for increasing parents' awareness of orthodontic problems in children.

Assessment of parental awareness about malocclusion in Shiraz, Islamic Republic of Iran

Information empowers people to take charge of their health. The aim of this study in Shiraz, Islamic Republic of Iran was to evaluate parents' knowledge about dental malocclusion, referral routes and information sources. A random sample of 1000 7-9-year-old schoolchildren were given a questionnaire to complete at home. Questionnaires were completed by 795 parents. Knowledge about malocclusion was significantly greater in families with higher levels of education and income. Most respondents [83.5%] were aware of the importance of maintaining primary teeth to prevent malocclusion, and 25.1% thought that carious primary teeth must be extracted. Half of the parents [50.6%] did not know that spaces between primary teeth are normal. Only 28.8% of the children visited dentists for annual routine check-ups. Television [43.3%] was the most common source of dental information. The level of general public awareness about malocclusion needs to be improved

Impact of an educational leaflet on parents' knowledge and awareness of children's orthodontic problems in Shiraz

Raising parents' awareness about dentofacial malocclusions is important for avoiding delays in seeking treatment. The aim of the present research was to assess the impact of an educational leaflet on parent's knowledge and awareness of orthodontic malocclusion in children. Parents of 533 7-9-year-old schoolchildren were randomized into a leaflet group who received an educational leaflet and a control group with no leaflet. Pre-and post-intervention test scores on a questionnaire about orthodontic problems were compared. Differences between post- and pre-test scores were significantly higher in the leaflet group than the control group for the total score and the domain on general awareness of orthodontic problems. Scores on the domain of knowledge of referral intervals did not differ significantly. Information leaflets may be useful for increasing parents' awareness of orthodontic problems in children

Prevalence of malocclusions in school-age children attending the orthodontics department of Shiraz University of Medical Sciences

To provide quantitative data about the prevalence of malocclusions in the Shiraz orthodontic population, we studied the records of 700 patients [391 girls and 309 boys] aged 6-14 years attending the undergraduate Department of Orthodontics at Shiraz University of Medical Sciences. The prevalence of Angle class I, II and III malocclusion of first molars was 52.0%, 32.6% and 12.3% respectively. Skeletal class I, II and III malocclusion was found in 18.0%, 70.0% and 12.0% respectively. There were no significant differences between the sexes in the prevalence of different types of skeletal malocclusion. Children with class III were significantly younger [mean age 8.9 years] than those with class I [9.6 years] or class II [9.7 years] malocclusions. Orthodontics students need more education and training in the management of class II malocclusion to improve the overall quality of care for patients

In vitro evaluation of force-expansion characteristics in a newly designed orthodontic expansion screw compared to conventional screws.

OBJECTIVE: Expansion screws like Hyrax, Haas and other types, produce heavy interrupted forces which are unfavorable for dental movement and could be harmful to the tooth and periodontium. The other disadvantage of these screws is the need for patient cooperation for their regular activation. The purpose of this study was to design a screw and compare its force- expansion curve with other types. MATERIALS AND METHODS: A new screw was designed and fabricated in the same dimension, with conventional types, with the ability of 8 mm expansion (Free wire length: 12 mm, initial compression: 4.5 mm, spring wire diameter: 0.4 mm, spring diameter: 3 mm, number of the coils: n0 ine, material: s0 tainless steel). In this in vitro study, the new screw was placed in an acrylic orthodontic appliance, and after mounting on a stone cast, the force-expansion curve was evaluated by a compression test machine and compared to other screws. RESULTS: Force-expansion curve of designed screw had a flatter inclination compared to other screws. Generally it produced a light continuous force (two to 3.5 pounds) for every 4 mm of expansion. CONCLUSION: In comparison with heavy and interrupted forces of other screws, the newly designed screw created light and continuous forces.