J Dent Educ. 71(8): 1070-1079 2007
© 2007 American Dental Education Association
Educational Methodologies |
The Impact of Targeted Shortened Preclinical Exercises on Student Perceptions and Outcomes
Cortino Sukotjo, D.D.S., Ph.D., M.M.Sc.;
Kewalin Thammasitboon, D.D.S., D.M.Sc.;
Howard Howell, D.D.S.;
Nadeem Karimbux, D.M.D., M.M.Sc.
Key words: clock hours, shortened preclinical exercises, self-confidence, didactic and laboratory preclinical exercises, national standard examination
Submitted for publication 11/25/06;
accepted 03/28/07
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Abstract
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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.
The Institute of Medicine report in the early 1990s recommended several changes in dental education curricula. In response to this suggestion, many dental schools such as Indiana University School of Dentistry (IUSD), University of Southern California School of Dentistry (USCSD), and Harvard School of Dental Medicine (HSDM) reformed their curricula at the conceptual and organizational levels.1–5
Problem-based learning (PBL) is the learning that results from the process of working toward the understanding or resolution of problems. The pedagogy of this method differs from traditional lecture-oriented programs. The PBL approach in medical education began at McMaster University in the mid-1970s and emphasized that the student and patient should be the center of educational process. The essence of the PBL method in health professions education involves three steps: 1) recognizing the problem and identifying its manifestations (symptoms/presentation) and health consequences; 2) engaging in independent study to explore the etiology of the problem and potential solutions (treatment); and 3) returning to the problem to apply potential solutions and analyze the outcomes. Consequently, students are expected to become "critical thinkers" instead of "information consumers."5 This pedagogy also builds a basis for self-evaluation and develops a strong group process for cooperative learning.6 Students learn in small groups using a case-based methodology specifically designed to integrate the basic and clinical sciences in an active, student- directed learning environment that aims to encourage self-reliance and reflection.7,8
Problem-based learning was integrated into the dental curriculum in 1994 at HSDM although it was first introduced in 1987 to the Harvard Medical School, where HSDM students share the first two years of the curriculum. HSDM’s commitment to the new curriculum resulted in a reinvention of the school, including its mission, organizational structure, faculty resources, financial management, and student expectations.5,9 As part of the reorganization, ten departments were consolidated into five departments. In addition to reducing the repetition and redundancy in the curriculum, courses began to be taught in an interdisciplinary fashion rather than with a discipline-based approach.10 This change mandated a reduction in lecture and preclinical clock hours; there was understandable concern among the faculty that this reduction would affect the students’ performance in the didactic and clinical portions of the curriculum. In particular, faculty members were very concerned about the impact on clinical competency because of the reduced time for preclinical hand-skill exercises. A previous study by Ferguson et al. in 2002 showed that although HSDM has the lowest preclinical operative dentistry laboratory hours in the nation, HSDM student performance in national and regional standard examinations was not affected.10
The objectives of this study were to expand upon the previous findings from the Ferguson et al. study by 1) comparing the HSDM didactic and laboratory preclinical hours in Endodontics, Operative, and Prosthodontics before and after PBL implementation; 2) comparing the current HSDM didactic and laboratory preclinical hours with other schools nationwide; 3) measuring students’ perceptions of their levels of stress and self-confidence at two time points during their clinical years (before entering the third-year clinic and prior to the termination of the fourth-year clinic); 4) investigating the correlation between the lab duration in Endodontics, Operative, and Prosthodontics preclinical exercises and the students’ confidence and stress level in the clinic; and 5) evaluating the impact of the shortened preclinical curriculum on HSDM students’ performance on the National Board Dental Examination Parts I and II.
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Methods
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National data on the didactic and preclinical curriculum hours in Endodontics, Operative, and Prosthodontics were obtained from the 1985–86 and 2003–04 American Dental Association (ADA) survey of predoctoral education. Clock hours of the didactic and preclinical laboratory instruction in Operative Dentistry, Endodontics, and Removable/Fixed Prosthodontics were compared between HSDM 1985–86 (pre-PBL), national mean 1985–86, HSDM 2003–04 (post PBL), and national mean 2003–04 (Figure 1
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Figure 1. Comparison of preclinical didactic, and laboratory hours in Endodontics, Operative, and Prosthodontics curricula at HSDM 1985–86 (pre-PBL), national mean 1985–86, HSDM 2003–04 (post-PBL), and national mean 2003–04
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A survey regarding student perceptions of stress and confidence on specific preclinical exercise was created and was approved by the Harvard Medical School Office for Research Subject Protection (Table 1). The survey was created based on Ferguson et al.10 with some modification and was distributed to HSDM classes of 2005 and 2006 (n=70). At HSDM, students spend their first two years at Harvard Medical School and start learning about core clinical dentistry in year 3. The first block in core clinical dentistry is treatment of active disease. The purpose of the course is to provide the concepts, skills development, and clinical skills/practice to facilitate the diagnosis, treatment planning, and clinical management of active dental disease. Preclinical Endodontics and Operative Dentistry are mainly taught in this block. Following this block is the Restorative block, which provides the student with didactic knowledge to formulate a comprehensive diagnosis, sequencing, and treatment plan for the Restorative needs of the patient. Prosthodontics is the main material taught during the Restorative block. The survey for this study consisted of two parts. Part I was distributed during the third year, at the end of the treatment of active disease block (after the completion of the Operative/Endodontics preclinical exercises) and the Restorative block (after the completion of the Prosthodontics preclinical exercises); part II (same as part I, only with fewer and modified questions) was distributed prior to the termination of the fourth-year clinic (Table 2).
National Board Dental Examination (NBDE) Parts I and II scores for the HSDM classes of 2005 and 2006 were also analyzed and compared to the national mean and the average scores for pre-PBL classes 1980 through 1991 and post-PBL classes 1998 through 2004. We did not use data from the HSDM classes of 1992–97 because, during that period, dental students participated in the medical school PBL in years one and two while dental classes were still taught in the traditional lecture-based format.
Relative frequencies were calculated for each of the variables. Cross-tabulations were constructed, and the Fisher’s exact test was conducted to examine the relationships between the variables. In all cases, alpha was set to 0.05. Analyses were conducted in Stata 6.0 (Stata Corp, College Station, TX). A one sample t-test was also used to determine whether the average scores of the HSDM classes of 2005 and 2006 on the NBDE Parts I and II, respectively, were statistically significantly different from the mean scores of all other U.S. dental schools. The Kruskal-Wallis test followed by the Mann-Whitney test were used to determine if the scores of the seventy students in the HSDM classes of 2005 and 2006 on Parts I and II of the NBDE were statistically different from the scores of the classes of 1980 through 1991 (pre-PBL) and 1998 through 2004 (post-PBL).
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Results
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The clock hours devoted to preclinical didactic and laboratory exercises in Endodontics, Operative, and Prosthodontics (combination of Fixed and Removable Prosthodontics) training before and after PBL implementation at HSDM and the national mean were obtained from the ADA 1985–86 and 2003–04 survey of predoctoral education. The ADA defines didactic instruction as classroom, seminar, conference, or self-instruction. The national mean clock hours for both didactic and laboratory in Endodontics, Operative, and Prosthodontics remain the same or slightly changed between 1985–86 and 2003–04 with the exception of the Prosthodontics laboratory. The clock hours for Endodontics and Operative (didactic and laboratory) were lower after the implementation of the new curriculum at HSDM except for the Prosthodontics laboratory hours (which were slightly higher). They remain lower than the national mean except for the Operative and Endodontic didactic hours before PBL implementation (Figure 1
).
Students’ Perceptions About Preclinical Exercises Before Entering Clinic
A survey to evaluate the students’ perceptions concerning stress levels, based on the duration of the laboratory exercises, adequacy of feedback from instructors, and preparedness for treating patients, was created and distributed to the HSDM class of 2005–06. The responses were pooled and a total response rate of 100 percent was achieved (see Table 3).
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Table 3. Results from Part I survey: students’ perceptions regarding preclinical exercises before entering clinic (all results in percentages)
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Level of Stress.
In response to question 1 (How would you rate your level of stress during the laboratory exercises?), the majority of the students (49 percent and 52 percent) reported feeling stressful in Operative and Prosthodontics but not in the Endodontics laboratory exercises.
Adequacy of Time Devoted to Preclinical Laboratory Exercises.
Seventy-eight percent and 63 percent of the students felt that the duration of the Endodontics and Operative laboratory exercises were just right, whereas 58 percent of the students felt the Prosthodontics exercises were too short.
Adequacy of Input/Feedback from Instructors.
During the Endodontics laboratory exercises, 56 percent of the students felt that the feedback they received from the preclinical laboratory instructors was just right, whereas the majority of the students (49–67 percent) felt that the feedback they received was not enough during the Operative and Prosthodontic laboratory preclinical exercises.
Adequacy of Knowledge Received from Lectures.
Seventy-two percent and 62 percent of the students felt that the knowledge they gained from the lectures in Endodontics and Operative were just right, whereas 54 percent of students felt that the knowledge they gained from the lectures in Prosthodontics was not adequate in preparing for the laboratory exercises.
In regard to Question 5 (Do you think the knowledge you obtained from lectures is helpful in preparing for clinical practice?), 69 percent, 63 percent, and 54 percent of the students responded Yes for Endodontics, Operative, and Prosthodontics, respectively.
Self-Confidence Level for Treating Patients in the Clinic.
Analysis of the data indicates that 65 percent of students felt unprepared for treating Prosthodontics patients, whereas the majority of student felt just right in treating Endodontics and Operative patients.
Adequacy of Hand/Clinical Skill Training for Treating Patients in the Clinic.
The response options for this question were did not have enough, just right, and more than enough. The majority of the students—49 percent, 48 percent, and 48 percent—answered just right for the amount of hand skill training for treating Endodontics, Operative, and Prosthodontics patients.
Seniors’ Perceptions in Comparison to Their Responses Prior to Starting Patient Care
Senior (fourth-year) HSDM students completed a virtually identical version of the same survey near the end of the curriculum. The following section reviews the responses of the senior students in comparison to their responses as junior students.
Laboratory Exercises Duration.
Before entering clinic, 78 percent and 63 percent of the junior students felt that the duration of laboratory exercises in Endodontics and Operative was just right, respectively, compared to 75 percent and 63 percent after they had finished clinical requirements as seniors (Figure 2A). In Prosthodontics, before entering clinic, 58 percent of the junior students felt that the laboratory exercises duration was too short compared to 57 percent after finishing clinical requirements in their senior year.
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Figure 2. Results from Part II survey: senior students’ perceptions regarding the adequacy of preclinical exercises in comparison to their responses prior to starting patient care
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Self-Confidence in Treating Patients in the Clinic.
Before entering clinic, 45 percent and 51 percent of the students felt that they were just right in treating Endodontics and Operative cases in the clinic, respectively, compared to 45 percent and 51 percent after finishing clinical requirements (Figure 2B). In Prosthodontics, before entering clinic, 65 percent of the students felt that they were unprepared in doing Prosthodontics procedures compared to 56 percent after finishing clinical requirements.
Adequacy of Clinical/Hand Skill Training in Treating Patients in the Clinic.
Before entering clinic, 49 percent and 48 percent of the students felt that their hand skill training was just right in treating Endodontics and Operative cases in the clinic, respectively, compared to 68 percent and 48 percent after finishing clinical requirements (Figure 2C). In Prosthodontics, before entering clinic, 48 percent of the students felt that their hand skill training was just right in treating Prosthodontics cases in the clinic. After finishing clinical requirements, the majority of students (52 percent) felt they did not have enough clinical skill in treating Prosthodontics patients in the clinic.
Scores on the NBDE Parts I and II.
Statistical analysis showed that HSDM students’ average scores for the classes of 2005 and 2006 on the NBDE Parts I and II, respectively, were statistically significantly different from the national mean scores for students at all U.S. dental schools (Table 4). HSDM’s average scores for the classes of 2005 and 2006 on the NBDE Part I were also statistically significant higher than HSDM pre-PBL average scores for the classes of 1980–91.
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Table 4. National Board Dental Examination Part I and Part II comparison between HSDM (2005–06) and HSDM pre-PBL, HSDM post-PBL, and nation
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The cross tabulation analysis between each variable in Endodontics, Operative, and Prosthodontics was set to a Fisher’s exact value of 0.05. The analysis revealed a significant correlation between students’ stress level and laboratory duration in Endodontics (f=0.028) and Operative (f=0.023). (See Table 5.) This analysis also revealed that laboratory duration and self-confidence were correlated for the three specialties: Endodontics (f=0.003), Operative (f=0.036), and Prosthodontics (f=0.00).
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Table 5. The summary of cross tabulation analysis between each variable in Endodontics, Operative, and Prosthodontics
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Discussion
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Major changes were made in the curriculum at HSDM in 1994. Courses (basic sciences or clinical dentistry) were taught in an interdisciplinary fashion. Every case that was presented in the tutorial section contained medical and dental information. Students were expected to be "self-learners" and not "information consumers" like in a lecture-based curriculum.
Interdisciplinary teaching in a PBL curriculum typically resulted in a reduction of preclinical didactic and laboratory hours. A comparison of HSDM’s clock hours in Endodontics, Operative, and Prosthodontics with the national mean based on ADA data revealed that the didactic and laboratory clock hours at HSDM are significantly lower than the national mean except for both the Endodontics (one hour higher) and the Operative didactic hours (sixteen hours higher) pre-PBL (1985–86 ADA report). In addition, the clock hours in Endodontics, Operative, and Prosthodontics in both the didactic and preclinical laboratory areas at HSDM were reduced significantly when the new hybrid-PBL curriculum was implemented. However, the clock hours in the Prosthodontics laboratory exercises at HSDM have increased although they are still significantly below the national average (Figure 1). This trend is due to the changes in the Operative-Prosthodontics curriculum. For example, before PBL implementation, some restorations such as inlay and onlay restorations were taught extensively during the Operative sections, whereas after PBL implementation, inlay and onlay restorations became a part of the Prosthodontics curriculum. Interestingly, the national trends in both didactic and laboratory have changed slightly or remained the same from year 1985–86 to year 2003–04 with the exception of the Prosthodontics laboratory hours (which is thirty-three hours shorter).
It could be conjectured that the reduction of clock hours in Endodontics, Operative, and Prosthodontics at HSDM might influence student performance in preclinical exercises, in clinical care, or on the National Board Dental Examination. Small class sizes and the PBL curriculum could be confounding factors in the result reported here. The relatively small class size at HSDM (thirty-five students per class) results in better faculty to student ratios. In the PBL curriculum, students also have opportunities to discuss and understand their clinical problems during tutorial sessions. The students work in groups to understand multidisciplinary clinical cases. These sessions should lead to a deeper understanding and learning of patient and clinical issues. Curriculum hours spent in tutorial may supplement time lost in lecture and laboratory.
The topic of stress and anxiety among dental students worldwide has received increasing attention in the dental literature in the past decade.12–15 Somatic effects such as fatigue, tension, dizziness, sleeplessness, anxiety and depression, and obsessive compulsive disorders have been reported extensively.15 In our study, the majority of the students felt that the Prosthodontics curriculum gave them the most stressful experience, followed by Operative and then Endodontics. This high stress level in Prosthodontics may come from extensive preclinical requirements, competency exams, and the inconsistency of professors’ feedback in the Prosthodontics curriculum.12 Interestingly, although the Restorative block is the longest curriculum component (six months) during the third year at HSDM, students still feel that the duration of the laboratory exercises in Prosthodontics is too short for them to learn. Students also feel that they had the least self-confidence levels, knowledge, and hand skill training in treating Prosthodontics cases compared to the other specialties, even though the Fisher’s exact statistical analysis failed to show the correlation between these variables. In comparing perceptions regarding laboratory preclinical exercises before entering clinic and after finishing clinical requirements, the results showed almost the same trend between preclinical and postclinical perception in all three disciplines with only one exception. After finishing their clinical requirements, more students felt that their clinical skill training during their preclinical exercises was not sufficient to treat Prosthodontics cases in the clinic compared to the other disciplines. It is difficult within the scope of this study to state if all dental students exhibited the same amount of stress in these three disciplines and if the students’ perceptions about stress are similar in all dental schools.
The HSDM classes of 2005–06 performed at a higher level on both the NBDE Part I and II than the national average and pre-PBL classes. In this study, we could not compare the HSDM classes of 2005–06 Part II scores with the pre-PBL Part II scores due to a change of grading system that occurred in 1994. The slightly lower average of HSDM NBDE Part II scores may be due the sense that the students are not that motivated in NBDE Part II compared to NDBE Part I as many have already been accepted to their residency program when they take Part II. Previous studies also showed that the implementation of PBL is independently associated with higher NBDE Part I scores.11
Although the preclinical hours at HSDM in these three specialties are lower than the national average, the outcomes from our prospective study show that the didactic knowledge of the students (as measured by NBDE Part I data) has not been affected by this change in curriculum. Despite the fact that the shortened clock hours may have resulted in a high anxiety level among the students, especially for Prosthodontics, the results suggest that students still performed well in didactic and clinical settings.
One of the advantages of creating a shorter, more clinically relevant, and organized curriculum is that some time saved could be used for doing extra activities such as research, community service, and small group exercises (case discussion and tutorial). Further studies need to be performed to investigate whether Prosthodontics is in fact a very difficult and stressful subject to learn nationwide.
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Limitations of the Study
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Despite the fact that HSDM has a small class cohort every year, our study also lacked true-control, non-PBL data, causing difficulties in drawing a completely quantitative comparison. Measuring clinical outcomes using the national standardized examination such as North East Regional Board (NERB) examination passing rate is also difficult since students have the right to decide if they want their results disclosed to their schools. Furthermore, in this study we did not investigate the source of stress among the students. It is possible that factors unrelated to the format of the curriculum contributed to student stress in the clinic. Future studies could explore the correlation of stress among dental students and adverse events in the clinic.
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Conclusion
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The implementation of PBL at the Harvard School of Dental Medicine has resulted in a shortened preclinical curriculum. The HSDM preclinical hours in Endodontics, Operative, and Prosthodontics were significantly lower than in other schools. A survey was conducted to assess HSDM predoctoral student perceptions regarding the adequacy of the Endodontics, Operative, and Prosthodontics preclinical curricula. The survey results showed that HSDM students felt more stressed during Prosthodontics preclinical exercises than in Endodontics or Operative Dentistry. Overall, the findings from this analysis indicate that the change to a PBL curriculum has not affected the clinical and didactic outcomes, but may have affected the anxiety that students feel when entering the clinic. An area for future research is to compare the perception of dental students from non-PBL schools about the preclinical curriculum variables investigated in this study to determine if the responses of the HSDM students differ from students trained in more traditional educational programs.
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Footnotes
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Dr. Sukotjo is an Instructor, Department of Restorative and Biomaterial Sciences, Harvard School of Dental Medicine; Dr. Thammasitboon is an Instructor, Division of Endodontology, Department of Conservative Dentistry, Prince of Songkla University; Dr. Howell is Professor of Periodontology and Dean of Dental Education, Harvard School of Dental Medicine; and Dr. Karimbux is Associate Professor of Periodontology and Assistant Dean of Dental Curriculum, Harvard School of Dental Medicine. Direct correspondence and requests for reprints to Dr. Nadeem Karimbux, Office of Dental Education, Harvard School of Dental Medicine, 188 Longwood Ave., Boston, MA 02115; 617-432-3881 fax; nadeem_karimbux{at}hsdm.harvard.edu.
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Abstract
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