Influence of periodontal ligament simulation and splints on strains developing at the cervical area of a tooth crown

Many in vitro tooth models do not incorporate periodontal ligament (PDL) simulation. This study presents the influence of physiologically loaded occlusal splints on cervical strains in a model incorporating roots and PDL. Four sets (N = 10) of occlusal splints differing in material (hard/soft) and location (upper/lower) were prepared for first maxillary and mandibular anatomic molars. Two strain gauges were bonded to the buccal and lingual aspects of the lower molar. Teeth were embedded in acrylic resin with/without a PDL‐simulating material. Force vs. strain data were acquired during loading and the maximal strains at 500 N were analyzed. When PDL was incorporated into the model without splints, buccal compressive strains were significantly decreased. Usage of a soft splint resulted in compressive strains on both tooth aspects. Usage of a hard splint on the lower tooth resulted in higher compressive strains on the lingual side compared with the buccal side, whereas usage of this splint on the upper tooth resulted in tensile strains on the lingual side. Bending towards the buccal side occurred when the splints were located on the upper tooth. Soft splints reduce buccal bending, but do not reduce cervical strains. Periodontal ligament stimulation materials should therefore be incorporated in models involving teeth.     

Pharmacokinetics of imidapril and its active metabolite imidaprilat following single dose and during steady state in patients with chronic renal failure

Objective: An open study on the single dose and steady-state pharmacokinetics of imidapril, a novel prodrug-type angiotensin-converting enzyme (ACE) inhibitor, and its active metabolite imidaprilat was conducted in eight patients with moderate chronic renal failure [mean creatinine clearance (CL_CR) 64 ml · min⁻¹; range 42–77 ml · min⁻¹], eight patients with severe chronic renal failure (mean CL_CR, 18 ml · min⁻¹; range 11–29 ml · min⁻¹) and eight healthy volunteers with normal renal function. Subjects received an oral dose of 10 mg imidapril once per day for 7 days. Results: No statistical differences of either maximum concentration (C_max) or the area under the curve (AUC) were found between patients with moderate renal failure and healthy subjects. However, C_max and AUC for both imidapril and imidaprilat were significantly higher in patients with severe renal impairment than in healthy volunteers. There were no clinically relevant differences among the three subject groups with regard to total urinary excretion of both imidapril and imidaprilat. Conclusion: The smallest imidapril dose which is clinically effective should be used in patients with severe renal insufficiency. Received : 11 July 1997 / Accepted in revised form : 6 October 1997     

Development, implementation and pilot evaluation of a Web-based Virtual Patient Case Simulation environment – Web-SP

Background  

The Web-based Simulation of Patients (Web-SP) project was initiated in order to facilitate the use of realistic and interactive virtual patients (VP) in medicine and healthcare education. Web-SP focuses on moving beyond the technology savvy teachers, when integrating simulation-based education into health sciences curricula, by making the creation and use of virtual patients easier. The project strives to provide a common generic platform for design/creation, management, evaluation and sharing of web-based virtual patients. The aim of this study was to evaluate if it was possible to develop a web-based virtual patient case simulation environment where the entire case authoring process might be handled by teachers and which would be flexible enough to be used in different healthcare disciplines.     

Virtual Patients in Primary Care: Developing a Reusable Model That Fosters Reflective Practice and Clinical Reasoning

Background

Primary care is an integral part of the medical curriculum at Karolinska Institutet, Sweden. It is present at every stage of the students’ education. Virtual patients (VPs) may support learning processes and be a valuable complement in teaching communication skills, patient-centeredness, clinical reasoning, and reflective thinking. Current literature on virtual patients lacks reports on how to design and use virtual patients with a primary care perspective.

Objective

The objective of this study was to create a model for a virtual patient in primary care that facilitates medical students’ reflective practice and clinical reasoning. The main research question was how to design a virtual patient model with embedded process skills suitable for primary care education.

Methods

The VP model was developed using the Open Tufts University Sciences Knowledgebase (OpenTUSK) virtual patient system as a prototyping tool. Both the VP model and the case created using the developed model were validated by a group of 10 experienced primary care physicians and then further improved by a work group of faculty involved in the medical program. The students’ opinions on the VP were investigated through focus group interviews with 14 students and the results analyzed using content analysis.

Results

The VP primary care model was based on a patient-centered model of consultation modified according to the Calgary-Cambridge Guides, and the learning outcomes of the study program in medicine were taken into account. The VP primary care model is based on Kolb’s learning theories and consists of several learning cycles. Each learning cycle includes a didactic inventory and then provides the student with a concrete experience (video, pictures, and other material) and preformulated feedback. The students’ learning process was visualized by requiring the students to expose their clinical reasoning and reflections in-action in every learning cycle. Content analysis of the focus group interviews showed good acceptance of the model by students. The VP was regarded as an intermediate learning activity and a complement to both the theoretical and the clinical part of the education, filling out gaps in clinical knowledge. The content of the VP case was regarded as authentic and the students appreciated the immediate feedback. The students found the structure of the model interactive and easy to follow. The students also reported that the VP case supported their self-directed learning and reflective ability.

Conclusions

We have built a new VP model for primary care with embedded communication training and iterated learning cycles that in pilot testing showed good acceptance by students, supporting their self-directed learning and reflective thinking.     

Clinical pharmacokinetics of the nifedipine/co-dergocrine combination in impaired liver and renal function.

Following a single oral dose of 20 mg nifedipine combined with 2 mg co-dergocrine to 24 subjects, the pharmacokinetics of this drug were studied. 8 normotensive subjects had normal renal and hepatic function, 8 patients had chronic renal insufficiency (creatinine clearance less than 30 ml.min-1) and 8 patients had liver cirrhosis which was confirmed by liver biopsy. The area under the plasma level time curve (AUC infinity) of co-dergocrine increased from 0.59 +/- 0.41 ng.ml-1. (mean +/- SD) in the normals to 1.24 +/- 0.95 ng.ml-1.h in liver cirrhosis (P less than 0.05) and to 1.81 +/- 0.9 ng.ml-1.h in renal failure (P less than 0.05 compared with the control group). Corresponding values for the nifedipine AUC infinity were 564.5 +/- 268 ng.ml-1.h, 1547.5 +/- 1134 (P less than 0.05) and 929 +/- 533 ng.ml-1.h (P less than 0.05; gas chromatographic method). The incidence of adverse effects was lower in patients with renal failure than in subjects with normal renal and liver function as well as in those with liver cirrhosis.