Ioxaglate-induced light and electron microscopic alterations in the renal proximal tubular epithelium of rats.

Vacuolization of the proximal tubular epithelial cells was produced in rats by the intravenous administration of the radiographic contrast medium ioxaglate at high multiples of the human diagnostic dose. Samples of the renal cortex and outer zone of the medulla were examined by light and electron microscopy. We observed enlargement, confluence, and migration of vacuoles containing pleomorphic dense material and distinct inclusion bodies. With time, vacuolization disappeared, though single vacuoles partly engaged in extruding their contents into the tubular lumen were still visible. We concluded that radiographic contrast medium at high dose levels can produce a reversible disturbance in the transport vesicular system of the proximal tubular epithelial cells without affecting the specific cell organelles.

Design and validation of mirror skills instruction.

Students contorted to achieve direct vision indicate that training of mirror skills is absent or ineffective. Training referenced in the literature is not described or amounts to practice using a mirror to perform a psychomotor task often marginally related to dental procedures. No complete task analysis of mirror use is reported. In this study, the authors applied instructional engineering principles to 1) analyze the task and design instruction, 2) validate instruction, and 3) foster mirror use. First-year students (experimentals) completed the new mirror instruction as well as the regular course instruction. A randomly selected group of second-year students who had not completed the mirror instruction but had completed a similar course comprised the control group for the validation. Sets of randomly grouped experimental subjects evaluated a maxillary preparation using mirror vision at three times during the semester and one time a year later. The controls evaluated the same preparation the first time only. Accuracy in describing the critical features of the preparation was used as an indicator of mirror skill. All subjects were observed for mirror use during a practical examination involving maxillary preparations. All groups were equivalent on entering GPA, DAT-A, and DAT-P. Experimental groups made significant improvement in measures of mirror vision skill over time. Experimental groups 2, 3, and 4 significantly outperformed controls on the same measures and demonstrated significantly higher rate of mirror use during the practical exam. The mirror skills instruction appears valid.

Discrimination training and formative evaluation for remediation in basic waxing skills.

In a quasi-experimental design the "experimental" group (n = 6) received discrimination training and self-evaluation exercises on four waxing projects and four handpiece projects over 13 hours. An equivalent "conventional" group (n = 7) received verbal feedback with models on seven waxing projects over 13 hours. Both groups took a posttest using plastic molars with two-surface preparations to be restored in wax. In blind evaluations of final products, the experimental group outperformed the conventional group. Results demonstrate the efficiency and effectiveness of structured discrimination and self-evaluation training in improving motor skills.

Using questions to facilitate motor skill acquisition.

For the process of question-guided problem-solving to work successfully, several conditions must exist: 1) presence of valid and reliable criteria for evaluating product (DO) and performance (DP), 2) development of learning resources such as life-sized examples, 3) training sessions in the application of criteria and use of the process for both faculty and students, and 4) faculty commitment to the process. The process helps to establish conditions in which learning occurs. Underlying its structure is the requirement for incorporation of discrimination tasks. Question-guided problem-solving structures the learner's approach to the task in a way that facilitates the refinement of independent learning strategies over time. Further, it promotes effective use of time in laboratory or clinic. Through repeated interactions, the faculty may better monitor student progress, diagnose student learning problems, suggest remedial strategies, and evaluate their outcomes. By providing instruction that includes opportunities to practice the subskills of problem-solving in an interactive cooperative environment, students systematically monitor learning by asking good questions and, through questioning, are empowered to solve problems.

Teaching recognition skills to improve products.

All 86 first year dental students in a Conservative Restorations course completed five sets of instructional tasks. Tasks followed a discrimination learning paradigm, a sequence based on the principal that recognition skills are a prerequisite for production skills. Recognition skill measures and production quality measures were collected for pre- and post-test Class 1 amalgam preparations. Significant improvement was found in three of the five recognition skill measures and in quality of production. Stepwise multiple regression analysis showed that a measure of student agreement with faculty evaluations accounted for 46.3 percent of the variance in post-test production scores whereas traditional admissions measures accounted for less than 4 percent of the variance. Additionally, students who improved recognition skill showed a corresponding improvement in products. The paradigmatic teaching model appears to be valid for Class 1 cavity preparations.

The effect of magnification on student performance in pediatric operative dentistry.

Previous research has shown that accurate student self-evaluation is related to higher quality dental products. Variance in student performance still remains. Enhancement of visual perception could contribute to product improvement. Only one study has evaluated the effects of magnification on simulated dental patient care. The present study sought to determine if magnification had a positive effect on student-generated products in pediatric amalgam preparations. Fifty-two third-year students were randomly assigned to experimental (magnification) or control (no magnification) groups. Members of the experimental group used magnification in their daily work in the pediatric dentistry clinic. No significant differences between the groups' preparations or evaluations of standard preparations were found. Further study should address these issues: 1) possible effects of specific training in the use of magnification devices; 2) whether the tolerance for error in dental preparations is so great that finer vision contributes little to product improvement; 3) the role of tactile sensation in evaluation and preparation; and 4) the possible benefits of magnification for effect of age. Based on this study, it seems that requiring students to purchase magnification devices may not be justified.

Long-term outcomes for remedial students.

A recent survey of dental schools concluded that current efforts toward remediation are inadequate. A remedial waxing course providing recognition training before production attempts, emphasis on formative self- and peer-evaluation of projects, and application of a highly structured format for ensuring relevant practice had been developed and favorably evaluated previously. The current report follows the progress of two differently trained remedial groups and the remainder of the class in two courses following remediation. On the five subsequent practical examinations analyzed, the experimental group continued to perform at the class mean. On one practical examination, the experimental group significantly outperformed the traditional group (p less than 0.02). For three of the five examinations, the traditional group was significantly outperformed by the class. One of the six students in the experimental group required additional remediation. Of the seven in the traditionally remediated group, one left school and four required additional remediation. An apparent changing remediation pattern in the preclinical training period is described and possible reasons for the change are explored.