Influence of various polishing methods on pulp temperature: An in vitro study

Objective: After orthodontic debonding, adhesive removal can lead to rises in pulp temperature, causing histological changes or pulp necrosis. The objective of this study was to measure increases in pulp temperature during adhesive removal using different instruments and various cooling procedures. Materials and methods: A thermoelement was introduced into the pulp chamber of 10human incisors. The teeth were immersed in a 36°C water bath up to the cementoenamel junction. Two carbide burs, one polishing disk and two rubber points were used for polishing. All measurements were taken over a 10s period by a single investigator, under slight pressure and with constant motion. Three cooling procedures were examined: no cooling, air cooling and water cooling. Pulp temperatures were measured before polishing and after 10s of polishing. Results: Without cooling, the two rubber points revealed clinically relevant temperature increases of 6.1°C and 12.4°C. Cooling with air and with water reduced pulp temperature in conjunction with all polishing methods. Air cooling was most efficient, except in combination with the polishing disk. Conclusion: Under these study conditions, carbide burs and polishing disks can be used safely and without risk to the pulp, even without cooling. On the other hand, rubber points cause a marked increase in pulp temperature when used without coolin

Influence of material choice on the force delivery of bimaxillary tooth positioners on canine malpositions

Objective: Since their introduction in 1945, tooth positioners have been used to treat a range of malpositions. Although the original appliance was made of natural rubber, today's tooth positioners are fabricated from various elastic, transparent materials. It was the aim of this study to evaluate the forces and moments produced by current positioners on various upper canine malpositions. Material and methods: Seven positioners of different materials were tested on 11 upper canine malpositions: 0.25, 0.5, 1mm supraposition; 0.25, 0.5, 1mm infraposition; 5°, 10°, 20° mesiorotation; 5° mesioinclination, 5° buccal root torque. We measured forces and moments in vitro after bite closure by 0.5mm, and opening by 1mm using a three-dimensional robotic device. All measurements were taken in a temperature-controlled environment at 36°C. Results: The forces and moments measured at the canine varied greatly among the different positioners, with the thermoformed EVA positioner showing much greater forces and moments in almost all malpositions. At initial closure, we observed intrusive forces of 6-32N for suprapositions, 0-11N intrusive forces for infrapositions, 0-20Nmm for mesiorotations, 6-12Nmm for mesioinclinations, and − 23Nmm to 5Nmm for buccal root torque. All positioners were most effective on suprapositioned teeth. Very low or negligible correctional forces and moments in conjunction with all infrapositions and 5° with rotation were noted. Labial root torque led to unpredictable moments. Conclusion: Positioner material plays a major role in delivering forces to the teeth. However, tooth positioners did not induce corrective forces in all the malpositions tested. Clinically relevant correctional forces or moments in conjunction with all suprapositions, rotations of 10° and 20° as well as mesial tipping of the canine were observe

Shear bond strengths of seven self-etching primers after thermo-cycling

Objective: Self-etching primers are widely used in restorative dentistry. However, only one primer has been developed for orthodontic applications. The objective of this study was to assess the suitabiliy of restorative self-etching primers on unabraded enamel. Material and Methods: Seven self-etching primers (Transbond™ SEP +, Xeno®III, Clearfil™SE, Futurabond®NR, OneCoat, M-Bond and OptiBond®) were compared with two conventionally-etched control groups (Transbond™ MIP). All groups with the exception of one of the two control groups underwent thermo-cycling (1000x, 5-55°C). Bovine teeth stored in physiological saline solution were used for the purpose of this study. Results: Both before and after thermo-cycling, the control groups presented very similar shear strengths which did not differ significantly from each other or from the Transbond™ SEP +  and Clearfil™SE specimens. During thermo-cycling, all groups except the control group and the Transbond™ SEP +  specimens displayed losses from the shear bodies. These losses occurred on all of the OptiBond® samples. The adhesive remnant index (ARI) and enamel tear-outs correlated closely with the adhesive values. Conclusions: Our adhesive value assessments support the conclusion that only Transbond™ SEP +  and Clearfil™SE can be recommended for clinical us

The influence of dental loupes on the quality of adhesive removal in orthodontic debonding

Objective: Bracket bonding has been a major advance in orthodontic treatment. However, the method of debonding can lead to diverse problems such as enamel fractures, enamel loss and enamel scratching. In this clinical investigation we aimed to evaluate the influence of wearing dental loupes on enamel damage during the debonding procedure. Material and Methods: 22 consecutive patients were randomly assigned in a split-mouth study to evaluate adhesive removal with and without the use of dental loupes (2.5×, LED headlight). Tooth replicas in epoxy resin were made from silicone impressions. Electron microscopic images (50× magnification) of 394 buccal enamel surfaces were evaluated according to an enamel damage index (EDI), line angle grooves (LAG) and composite residues (CR) on anterior teeth, premolars and molars. Results: The EDI revealed highly significant advantages for debonding with dental loupes, with which the EDI was significantly higher for molars, while still less than without dental loupes. We detected no differences between the tooth groups without dental loupes. We found significantly fewer LAG on anterior teeth debonded with dental loupes. CR were fewer in the dental loupes group, and we noted no significant differences between the tooth groups. Conclusions: Dental loupes affect the quality of the debonding procedure, resulting in less enamel damage and composite residue, as well as fewer LAG compared to the control group. We therefore strongly recommend the use of dental loupes in orthodontic debonding procedure

Disordered Environments in Spatial Games

The Prisoner's dilemma is the main game theoretical framework in which the onset and maintainance of cooperation in biological populations is studied. In the spatial version of the model, we study the robustness of cooperation in heterogeneous ecosystems in spatial evolutionary games by considering site diluted lattices. The main result is that due to disorder, the fraction of cooperators in the population is enhanced. Moreover, the system presents a dynamical transition at $\rho^*$, separating a region with spatial chaos from one with localized, stable groups of cooperators.Comment: 6 pages, 5 figure

An economic analysis of email-based telemedicine: A cost minimisation study of two service models

<p>Abstract</p> <p>Background</p> <p>Email-based telemedicine has been reported to be an efficient method of delivering online health services to patients at a distance and is often described as a low-cost form of telemedicine. The service may be low-cost if the healthcare organisation utilise their existing email infrastructure to provide their telemedicine service. Many healthcare organisations use commercial-off-the-shelf (COTS) email applications. COTS email applications are designed for peer-to-peer communication; hence, in situations where multiple clinicians need to be involved, COTS applications may be deficient in delivering telemedicine. Larger services often rely on different staff disciplines to run their service and telemedicine tools for supervisors, clinicians and administrative staff are not available in COTS applications. Hence, some organisations may choose to develop a purpose-written email application to support telemedicine. We have conducted a cost-minimisation analysis of two different service models for establishing and operating an email service. The first service model used a COTS email application and the second used a purpose-written telemedicine application.</p> <p>Methods</p> <p>The actual costs used in the analysis were from two organisations that originally ran their counselling service with a COTS email application and later implemented a purpose-written application. The purpose-written application automated a number of the tasks associated with running an email-based service. We calculated a threshold at which the higher initial costs for software development were offset by efficiency gains from automation. We also performed a sensitivity analysis to determine the effect of individual costs on the threshold.</p> <p>Results</p> <p>The cost of providing an email service at 1000 consultations per annum was $19,930 using a COTS email application and$31,925 using a purpose-written application. At 10,000 consultations per annum the cost of providing the service using COTS email software was $293,341 compared to$272,749 for the purpose-written application. The threshold was calculated at a workload of 5216 consultations per annum. When more than 5216 email consultations per annum are undertaken, the purpose-written application was cheaper than the COTS service model. The sensitivity analysis showed the threshold was most sensitive to changes in administrative staff salaries.</p> <p>Conclusion</p> <p>In the context of telemedicine, we have compared two different service models for email-based communication – purpose-written and COTS applications. Under the circumstances described in the paper, when workload exceeded 5216 email consultations per annum, there were savings made when a purpose-written email application was used. This analysis provides a useful economic model for organisations contemplating the use of an email-based telemedicine system.</p

Psoriasis Carries an Increased Risk of Venous Thromboembolism: A Danish Nationwide Cohort Study

Psoriasis is an immunoinflammatory disease associated with cardiovascular risk factors, atherothrombotic events, and hypercoagulability. Venous thromboembolism (VTE) is potentially lethal and shares risk factors with psoriasis, but the risk of VTE associated with psoriasis is unknown. The present study investigated the potential association between psoriasis and VTE.Information from nationwide prospectively recorded registers of hospitalization, drug dispensing from pharmacies, socio-economic data, and causes of death was linked on an individual level. In an unselected nationwide cohort, we used multivariate Poisson regression models controlling for age, gender, comorbidity, concomitant medication, socio-economic data, and calendar year, to assess the risk of VTE associated with psoriasis. A total of 35,138 patients with mild and 3,526 patients with severe psoriasis were identified and compared with 4,126,075 controls. Patients with psoriasis had higher incidence rates per 1000 person-years of VTE than controls (1.29, 1.92, and 3.20 for controls, mild psoriasis, and severe psoriasis, respectively). The rate ratio (RR) of VTE was elevated in all patients with psoriasis with RR 1.35 (95% confidence interval [CI] 1.21–1.49) and RR 2.06 (CI 1.63–2.61) for mild and severe psoriasis, respectively. Exclusion of patients with malignancies, and censoring of patients undergoing surgery did not alter the results.This nationwide cohort study indicates that patients with psoriasis are at increased risk of VTE. The risk was highest in young patients with severe psoriasis. Physicians should be aware that patients with psoriasis may be at increased risk of both venous and arterial thromboembolic events