PBL in the undergraduate MD program at McMaster University: three iterations in three decades.

When the undergraduate MD program of McMaster University admitted its first cohort of 20 students in 1969, it heralded a major change in medical school pedagogy that has influenced the education of medical students around the world. The three-year PBL curriculum, which emphasized small-group tutorials, self-directed learning, a minimal number of didactic presentations, and student evaluation that was based almost entirely on performance in the tutorial, represented a radical departure from traditional curricula. Since the inception of the original curriculum in 1969, there have been two major curriculum revisions, the most recent of which was in 2005. The original curriculum attempted to integrate both basic science and clinical science into the biomedical problems. The second iteration of the curriculum focused on priority health problems and centered on a list of common medical problems as the foundation for curriculum organization, on the basis that an understanding of the management of common conditions included areas of knowledge that would be essential for clinical competence. Under the third, current curriculum, the COMPASS (concept-oriented, multidisciplinary, problem-based, practice for transfer, simulations in clerkship, streaming) model was adopted. Under this concept-based system, emphasis is placed on underscoring the underlying concepts in the curriculum with a logical sequencing of both the concepts and the body systems. This article briefly reviews the history of the development of the undergraduate MD program at McMaster and the three curricula that have been developed during the past three decades.     

Comparison of B-mode and echo tracking methods of assessing flow-mediated dilation

The aim of this study was to compare B-mode and echo tracking methods to assess endothelium-dependent flow-mediated dilation (FMD). Baseline brachial artery diameter, 60-s post cuff release diameter and FMD percent were assessed in 17 normal, healthy individuals using both techniques. Mean values for baseline diameter, 60-s diameter and FMD for M-mode were 3.83 +/- 0.69 mm, 4.06 +/- 0.66 mm and 6.35 +/- 3.98%, respectively. Mean values for baseline diameter, 60-s diameter and FMD for B-mode were 3.75 +/- 0.65 mm, 4.00 +/- 0.63 mm and 6.91 +/- 2.85%, respectively. Results, as displayed by Bland-Altman graphs, indicate a strong agreement between B-mode and echo tracking methods of assessing brachial artery diameter changes via FMD.     

Comparison of 2 Canal Preparation Techniques in the Induction of Microcracks: A Pilot Study with Cadaver Mandibles

Introduction

The purpose of this pilot study in a cadaver model was to compare 2 different shaping techniques regarding the induction of dentinal microcracks.

Methods

Three lower incisors from each of 6 adult human cadaver skulls were randomly distributed into 3 groups: the control group (CG, no instrumentation), the GT group (GT Profile hand files; Dentsply Tulsa Dental, Tulsa, OK), and the WO group (WaveOne; Dentsply Tulsa Dental). In the GT group, manual shaping in a crown-down sequence with GT Profile hand files was performed. In the WO group, Primary WaveOne files were used to the working length. Teeth were separated from the mandibles by careful removal of soft tissue and bone under magnification. Roots were sectioned horizontally at 3, 6, and 9 mm from the apex using a low-speed saw. Color photographs at 2 magnifications (25× and 40×) were obtained. Three blinded examiners registered the presence of microcracks (yes/no), extension (incomplete/complete), direction (buccolingual/mesiodistal), and location. Data were analyzed with chi-square tests at P < .05.

Results

Microcracks were found in 50% (CG and GT) and 66% (WO) of teeth at 3 mm, 16.6% (CG) and 33.3% (GT and WO) at 6 mm, and 16.6% in all 3 groups at 9 mm from the apex. There were no significant differences in the incidence of microcracks between all groups at 3 (P = .8), 6 (P = .8), or 9 mm (P = 1). All microcracks were incomplete, started at the pulpal wall, and had a buccolingual direction.

Conclusions

Within the limitations of this pilot study, a relationship between the shaping techniques (GT hand and WaveOne) and the incidence of microcracks could not be shown compared with uninstrumented controls.