The impact of targeted shortened preclinical exercises on student perceptions and outcomes.

The Harvard School of Dental Medicine (HSDM) introduced problem-based learning (PBL) into the dental curriculum in 1994 as a part of curriculum reform. During the reorganization, departments were consolidated, and courses were taught in an interdisciplinary fashion rather than in a discipline-based approach. The changes required a reduction in lecture and preclinical clock hours, which might have affected student performance and anxiety levels. The objectives of this study were to 1) compare the HSDM didactic and laboratory preclinical hours in Endodontics, Operative, and Prosthodontics before and after PBL implementation; 2) compare the HSDM didactic and laboratory preclinical hours in Endodontics, Operative, and Prosthodontics with other schools nationwide; 3) measure students' perceptions of their levels of stress and self-confidence at two time points during their preclinical and clinical years; 4) investigate the correlation between the number of preclinical hours and the students' stress level and self-confidence; and 5) evaluate the impact of shortened preclinical hours on the performance of HSDM students on the National Board Dental Examination Parts I and II. A survey regarding the students' level of stress, self-confidence, and preparation to treat patients during preclinical laboratory exercises was distributed to the HSDM classes of 2005 and 2006 (n=70). The HSDM preclinical curriculum hours were compared to national data as reported by the American Dental Association (ADA). Cross-tabulations were constructed, and the Fisher's exact test was conducted to examine the relationships between the variables. We found that HSDM preclinical hours in Endodontics, Operative, and Prosthodontics were significantly lower than at other schools. During the preclinical exercises, the Prosthodontics preclinical exercises were found to be the most stressful and provided the lowest self-confidence in treating patients as compared to the other preclinical subject areas. HSDM students' scores on the National Board Part I and II examinations continue to be among the highest in the nation and have not been affected by the change in curriculum. We conclude that the change in HSDM's curriculum that resulted in targeted, shorter preclinical exercises has not affected clinical and didactic outcomes, but may have affected the anxiety that students feel when entering the clinic.