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Application of Basic Science to Clinical
Problems: Traditional vs. Hybrid Problem-
Based Learning
Amber N. Callis, D.D.S., M.S.; Ann L. McCann, R.D.H., Ph.D.;
Emet D. Schneiderman, Ph.D.; William J. Babler, Ph.D.; Ernestine S. Lacy, D.D.S.;
David Sidney Hale, D.D.S., M.S.D.
Abstract: It is widely acknowledged that clinical problem-solving is a key skill for dental practitioners. The aim of this study was
to determine if students in a hybrid problem-based learning curriculum (h-PBL) were better at integrating basic science knowl-
edge with clinical cases than students in a traditional, lecture-based curriculum (TC). The performance of TC students (n=40) was
compared to that of h-PBL students (n=31). Participants read two clinical scenarios and answered a series of questions regarding
each. To control for differences in ability, Dental Admission Test (DAT) Academic Average scores and predental grade point aver-
ages (GPAs) were compared, and an ANCOVA was used to adjust for the significant differences in DAT (t-test, p=0.002). Results
showed that h-PBL students were better at applying basic science knowledge to a clinical case (ANCOVA, p=0.022) based on
overall scores on one case. TC students' overall scores were better than h-PBL students on a separate case; however, it was not
statistically significant (p=0.107). The h-PBL students also demonstrated greater skills in the areas of hypothesis generation
(Mann-Whitney U, p=0.016) and communication (p=0.006). Basic science comprehension (p=0.01) and neurology (p<0.001)
were two areas in which the TC students did score significantly higher than h-PBL students.
Dr. Callis is Clinical Assistant Professor of Pediatric Dentistry, University of Texas Health Science Center at Houston Dental Branch; Dr. McCann is Associate Professor and Director of Planning and Assessment, Baylor College of Dentistry; Dr. Schneiderman is Associate Professor of Biomedical Sciences, Baylor College of Dentistry; Dr. Babler is Associate Professor and Acting Chairman, Department of Oral Biology, Indiana University; Dr. Lacy is Associate Professor and Director, Office of Student Development, Baylor College of Dentistry; and Dr. Hale is Assistant Professor of Pediatric Dentistry, Baylor College of Dentistry. Direct correspondence and requests for reprints to Dr. Amber N. Callis, University of Texas Health Science Center at Houston Dental Branch, 6516 M.D. Anderson Blvd., Houston, TX 77030; 832-594-3572 phone; 713-272-7616 fax; [email protected]. Keywords: problem-based learning, dental curriculum, basic science, assessment Submitted for publication 12/8/09; accepted 4/6/10 Problem-based learning (PBL) in health care exist for the cases, but the process allows students to education originated in the 1970s at McMaster reason and sort through various options and discuss University School of Medicine in Canada.1 them with others in the small group.1 It has since been incorporated into many medical PBL allows basic science knowledge to be school curricula and that of a few dental schools. made applicable to students' learning needs by relat- The typical format of a PBL curriculum involves a ing it to a clinical problem. It allows students to be group of usually six to eight students with a trained self-directed in their learning, and the motivation is faculty mentor or tutor. The students are given a no longer placed on memorizing facts for a multiple- clinical case with various issues that will need to choice exam. Instead, knowledge must be gained and be addressed in order to arrive at a solution to the understood in order to apply it to the clinical scenario problem. Students work collaboratively to develop and ultimately better serve the future patient.2 a problem list and hypotheses for the case, and are The past decade and a half have seen much subsequently responsible for independently gather- debate on the direction of dental education and the ing relevant information to share with the group. The practice of dentistry. In the Institute of Medicine's faculty mentor has the responsibility of guiding the 1995 report on the state of dental education, the need group throughout the case, not to serve as a source for change in dental education was clearly outlined.3 of information. Usually, a single solution does not Three of the five major themes identified in that re- October 2010 ■ Journal of Dental Education port highlighted the importance of better preparing PBL curriculum performed significantly worse than students to apply basic science to clinical problems. their traditionally educated counterparts on Part I of Those themes were as follows: 1) dental profession- the United States Medical Licensing Examination als need more comprehensive medical knowledge; 2) (USMLE). This result was based on a meta-analysis dental educators need to teach and display desirable of thirty-five research studies over a twenty-two-year models of clinical practice; and 3) dental schools period. Another study conducted by Blake et al.9 need to experiment with different models of educa- found that medical students in a PBL curriculum per- tion, practice, and performance assessment. formed significantly better on USMLE Step 1. This The practice of evidence-based dentistry (EBD) study compared the performance of students enrolled has been one of the leading trends in dentistry and at the University of Missouri–Columbia School of dental education. Evidence-based dentistry is the Medicine over a six-year period, during which the application of results from relevant clinical studies school transitioned to a PBL format. Statistically combined with the clinician's expertise and patient significant scores improved from an average of 199 values.4 If dentistry does not embrace evidence-based to an average score of 221. practice as a profession, it risks stagnation. While A retrospective study10 conducted at Harvard dental research has remained on the cutting edge, School of Dental Medicine found that students in a EBD serves as an arena in which technical scientific PBL curriculum received superior National Board research is made clinically applicable to practitioners. Dental Examination (NBDE) Part I scores com- When practitioners are not familiar and comfortable pared to students in the traditional curriculum. The with the practice of EBD, then the potential for stag- NBDE Part I average ranged from 91.3 to 94.6 over nation in the practicing world of dentistry arises. PBL the twenty-year period in which the change to PBL often provides a mechanism for students to attain was implemented. After the University of Southern basic skills in the practice of EBD because students California School of Dentistry converted to a PBL must critically review research to create hypotheses curriculum, its students' NBDE Part I scores were and develop solutions to clinical problems. Establish- also found to have improved.1,11 ing this habit during dental school might better equip The performance of students in a PBL curricu- students to continue this trend after graduation. lum on multiple-choice exams is often questioned by The American Dental Education Association's academicians. A recently published study12 by von Commission on Change and Innovation in Dental Bergmann et al. found that there was a significant Education (ADEA CCI) has addressed various issues positive correlation between student performance facing the future of dental education.5-7 Members of on multiple-choice content exams and process skills the ADEA CCI have recommended a dental curricu- examinations such as the triple jump. In this retro- lum that promotes lifelong and self-directed learning, spective study, data were collected for students at the scientific discovery and the integration of knowledge, University of Southern California Herman Ostrow and evidence-based oral health care.7 This call for School of Dentistry after its complete transition action also emphasized the need to integrate basic to a PBL curriculum. The scores for students dur- science with clinical science when considering cur- ing their first and second years were analyzed and riculum decompression and noted that if students are compared. While the two exams measured different to practice EBD, it is pivotal that they understand types of understanding, they showed that students research, are able to analyze and solve oral health who genuinely understood the subject matter could be problems, and can apply basic science principles to successful with both types of assessment. The authors day-to-day clinical scenarios. Another ADEA CCI were successful in supporting Butler et al.'s claim that article recommended that the new dental curricu- "true PBL is not skill-oriented—it is understanding- lum should "enhance the level of inquiry, research oriented."13 This type of research in dental education experience, and the applications of relevant science is limited, however. Additionally, there were not any to clinical problems."5 studies available that assessed hybrid problem-based While many studies have attempted to inves- learning. This further emphasizes the need for ad- tigate the effects of a problem-based curriculum in medical and dental education, the focus has usually Our study assessed the ability of students to been on performance on national board exams. Ver- apply the basic science knowledge acquired during non and Blake8 reported that medical students in a the first two years of dental school to clinical sce- Journal of Dental Education ■ Volume 74, Number 10 narios. The performance of students in a traditional based on sample scenarios used by other medical lecture-based curriculum was compared to that of and dental institutions. Biomedical science faculty students in a hybrid PBL curriculum. The aim of the at both institutions also aided in the creation of the study was to determine if students in the hybrid PBL scenarios and development of acceptable and ap- curriculum were better at integrating basic science propriate responses. A scoring rubric was developed knowledge with clinical cases than the students in a to measure student performance. Several established traditional curriculum. rubrics were consulted for the creation of the scoring rubric for this study.15,16 (See Figures 1 and 2 for Case I and its scoring rubric and Figures 3 and 4 for Case Materials and Methods
II and its scoring rubric.) The instrument was pilot-tested with nineteen Indiana University School of Dentistry graduate students at BCD before being used in the (IUSD) utilizes a hybrid PBL curriculum. A "true" study, and the wording of some questions was modi- PBL curriculum would be formatted such that all fied based on the results. There were no changes to learning needs are met with clinical problems in the scoring rubric. the small-group scenario. In a hybrid PBL format, Third-year dental students at BCD and IUSD conventional teaching modalities are combined with were the population for this study. The BCD students PBL settings. At IUSD specifically, some of the basic represented the traditional curriculum group (TC), science content is introduced to students in lecture and the IUSD students represented the hybrid PBL and reinforced with the PBL component, while other group (h-PBL). A power analysis determined that topics are taught solely in the lecture setting or solely forty participants in each group would be needed within the clinical problem. Thus, the combination to detect a 10 percent difference in performance, if of traditional and PBL methods makes it a hybrid of present (where α=.05, β=.20). In an effort to ensure the two. The PBL portion of the curriculum extends that each group had forty participants, more students throughout all four years of dental school. were invited to participate than necessary. Baylor College of Dentistry (BCD) uses a tra- All ninety-two students in the BCD 2007–08 ditional curriculum. Courses are divided by subject third-year class were invited to participate in the matter and taught separately from one another. The study. Students received a letter from the principal lecture format is the predominant mode of informa- researcher (AC) inviting them to participate, and a tion transmission, and there is little student interac- total of forty BCD students participated. Students tion. This type of curriculum is teacher-centered, in in the IUSD 2007–08 third-year class and 2008–09 contrast to student-centered PBL. In general, the third-year class were also invited to participate basic sciences are introduced and studied during the using the same procedure. Ultimately, thirty-one first two years, with the focus shifting to the clinical IUSD students enrolled in the study: fifteen from sciences in the last years of training. The clinical the 2007–08 third-year class and sixteen from the component of the curriculum is not combined with 2008–09 third-year class. the core sciences curriculum. This type of curriculum is what most students have encountered throughout their academic lives. Testing, Scoring, and Analysis
In this type of investigation, there is the risk Instrument Design and Sampling
that the two groups might have varying academic abilities that would affect the outcome of the study. To Because essay exams may be the most appropri- control for ability, Dental Admission Test Academic ate assessment tool for PBL,14 an essay examination Average (DAT AA) scores and predental grade point format was chosen as the assessment tool for this averages (GPAs) were collected to determine if there investigation. To reduce the effects of known limita- were any statistical differences in ability between tions (content specificity and inability to generalize), the two groups. Students participating in the study several short-answer essays were included, as well as released their DAT AA scores and predental GPAs more than one clinical scenario. Each case booklet to the principal researcher. contained two clinical cases followed by a series of All participants were randomly assigned a open-ended questions relating to the case. The prin- number between 1 and 80, and each was instructed cipal investigator developed the clinical scenarios to complete a case booklet with that designated October 2010 ■ Journal of Dental Education John is a 52-year-old African American male who presents to your dental office for a scaling and root planing appointment. No known drug allergies Metformin (biguanide) High Blood Pressure Atenolol (beta blocker) John stated at his initial appointment that his blood glucose values are usually 190-300 mg/dL (normal value <180 mg/dL). His hemoglobin A1C was 10.5 the last time he visited his physician, which he states was an improvement from 3 months before. John has severe periodontal disease due to prolonged neglect of his oral health. Thirty minutes into the appointment, John becomes pale, agitated, and confused and begins sweating. John then tells you that he took his medicine as usual this morning, but did not have time to eat breakfast. He did not want to be late to his cleaning appointment.
Hemoglobin A1C Value
Good control for diabetes Fair control for diabetes Poor control for diabetes What is currently happening to John? DIAGNOSIS Hypoglycemic attack or insulin shock Why has his behavior changed suddenly? PHYSIOLOGY John took his insulin this morning without eating.
His insulin has taken effect, and he does not have an excess of glucose in his blood. With the insulin working, he is subsequently hypoglycemic due to its effects (uptake of glucose from the blood). How would you manage John's current issue? TREATMENT Give sugar: juice, frosting, IV dextrose Compare and contrast Type 1 and Type 2 diabetes. Explain what you know about diabetes on a systems level. Be as detailed as possible. PHYSIOLOGY Type 1: autoimmune disorder, insulin-dependent diabetes mellitus Body destroys its own pancreatic beta cells Pancreatic beta cells responsible for the production of insulin Type 2: non-insulin-dependent diabetes mellitus Pancreatic beta cells produce less insulin, or body is resistant to effects of insulin Insulin responsible for uptake of glucose from bloodstream; if ineffective, excess amounts are present in blood and urine Circulatory effects include atherosclerosis and high blood pressure Also affects nerves, retina, and renal glomerulus John has complained of a burning tongue and tingling sensations. What has led to this symptom? NEUROLOGY Diabetic neuropathy High blood glucose levels for extended periods of time leading to a chemical change in nerves and impairment of ability to transmit signals Increased uptake of glucose by Schwann cells causing increased water uptake and cellular injury Damage to blood vessels carrying oxygen and nutrients to nerves How do John's medications work? PHARMACOLOGY Insulin lispro: causes body to uptake glucose from the bloodstream to be stored Metformin: exact mechanism of action unknown Associated with decrease in hepatic gluconeogenesis Associated with decrease in intestinal glucose absorption Improves insulin sensitivity Lipitor: inhibits HMG-CoA reductase enzyme leading to reduced cholesterol synthesis Atenolol: selective beta one adrenergic antagonist Beta one cells play a role in cardiac output and rennin release from juxtaglomerular cells What does Hemoglobin A1C measure, and why is it an indicator of how well an individual's diabetes is controlled? Glycosylation of hemoglobin A forms Hb A1C in red blood cells Hb A1C is present in all individuals and in increased levels of diabetics Reflects glucose levels in blood over the 6-12 weeks before the test, therefore good indicator of control Not affected by fluctuating levels of blood glucose Figure 1. Case I in the study with subject area and acceptable answers
Journal of Dental Education ■ Volume 74, Number 10 Integrates none of the Integrates 1 of the Integrates 2–3 of the Integrates 4 or more Identifies 0 key points Identifies 1–3 key Identifies 4 –7 key Identifies 8 or more key Identifies 0 key points Identifies 1 key point Identifies 2–4 key Identifies 5 or more key Identifies 0 key points Identifies 1–2 key Identifies 3–6 key Identifies 7 or more Identifies 0 key points Identifies 1 or fewer Identifies 2–3 key Identifies 4 or more key Identifies the correct Identifies the correct Work is unfocused Organization apparent Organization is clear; and poorly organized; but inconsistent; some transitions between connection of ideas Hypothesis is unclear, generation (why is too simplistic, or although gaps exist integrative thought and is developed clearly Figure 2. Scoring rubric for Case I
number. Study participants were given one hour to patient. All of the students participated over a five- complete the booklet. Participants were asked to month period. Because the participating students did answer each question as thoroughly as possible and not complete the case booklet at the same time, they were not allowed to ask any questions of the proctor. were asked not to share any information regarding Most students participated during their lunch hour or the cases or the investigation with other students. after school. A smaller group of students participated The following subject areas were analyzed during clinic sessions if they did not have a scheduled with Case I: physiology, neurology, pharmacology, October 2010 ■ Journal of Dental Education Angela is a 21-year-old Caucasian female. She presented to your dental office yesterday for an emergency appointment. Angela is complaining of pain on the lower right side of her jaw and has minor intraoral swelling.
Birth control pills No known drug allergies Advil as needed for pain The emergency exam yesterday revealed a severely decayed and infected #32 that needs to be extracted.
Radiographically, a large radiolucency was present at the apex of #32. You also noticed that the gingiva around #17 is erythematous. Angela says that it is not bothering her, however. You are concerned that you will be unable to obtain profound anesthesia, so you prescribe a 7-day course of amoxicillin and tell Angela to return in one week to have tooth #32 extracted. Today, Angela has returned with a large facial swelling on the right side. The swelling is fluctuant and extends below the border of the mandible.
What potential medical emergency concerns you the most about this scenario? How would you manage it? IV antibiotics, maintain airway, remove source of infection, incise and drain, refer to oral surgeon Describe three of the anatomical spaces potentially involved with this case. ANATOMY In general terms, describe the process of inflammation. IMMUNOLOGY Cardinal signs: redness, swelling, pain, fever, loss of function Infiltration of plasma and leukocytes into tissue Increase in blood flow to infected or injured area Histamine release: arteriole dilation and increased venous permeability Pus formation; increase in PMN numbers and C-reactive protein Pain receptors activated Resolution of inflammatory process by tissue growth factor and inhibition of pro-inflammatory molecules What other structures may be affected by the inflammation, and what are the consequences of that? ANATOMY, Lingual nerve: paresthesia potentially Lymph nodes: lymphadenopathy Surrounding bone: destruction due to infectious process Why did the amoxicillin not work? What makes clindamycin the antibiotic of choice in this scenario? Amoxicillin is a broad spectrum antibiotic, which does not significantly target anaerobic bacteria.
Clindamycin is very effective against anaerobic bacteria.
This infection involves more anaerobic bacteria as the infection has spread into deeper tissues.
You did not want to extract the tooth yesterday because you thought you would not achieve profound anesthesia. In general terms, which pain receptors are involved and what is the purpose of each? NEUROANATOMY A delta fibers: fast pain Respond to mechanical and thermal stimulation C fibers: slow pain Respond to chemical stimulation Figure 3. Case II in the study with subject area and acceptable answers
Journal of Dental Education ■ Volume 74, Number 10 Basic Science
Integrates none of the Integrates 1 of the Integrates 2–3 of the Integrates 4 or more Identifies 0 key Identifies 1–2 key Identifies 3–5 key Identifies 6 or more key Identifies 0 key Identifies 1–2 key Identifies 3–5 key Identifies 6–8 key Identifies 0 key Identifies 1 key point Identifies 2 key points Identifies 3 or more key Identifies 0 key Identifies 1 key point Identifies 2 key points Identifies 3 or more key Identifies 0 key Identifies 1 key point Identifies 2–3 key Identifies 4 or more key Clinical
Identifies the correct Identifies a partially Identifies the correct Work is unfocused Organization apparent Organization is clear; and poorly organized; but inconsistent; some transitions between connection of ideas Hypothesis is unclear, generation (why is too simplistic, or generally clear, although gaps exist integrative thought and is developed clearly Figure 4. Scoring rubric for Case II
and biochemistry. For Case II, the following areas pothesis generation. Total points were summed for were addressed: anatomy, immunology, physiology, each individual case. Except for total points, all other microbiology, and neuroanatomy. Overall science scores were based on a scale of 0 to 3 points. comprehension was evaluated with both cases along Data were analyzed with parametric and non- with diagnosis, treatment, communication, and hy- parametric tests when appropriate using SPSS v. October 2010 ■ Journal of Dental Education 15.0 statistical software. Statistical significance was with a sample size of forty students per group. The defined as a p value <0.05. A student's t-test was used actual power for Case I was 80.2 percent with Ns of to determine if the TC and h-PBL groups differed 40 and 31 for the TC and h-PBL groups respectively. regarding DAT AA and GPA scores. To control for If forty students would have participated in both differences in ability between the two groups, an anal- groups, the power would have been 83.4 percent. ysis of covariance (ANCOVA) test was performed Thus, there was only a slight diminution in power using DAT AA values as the covariate, and total based on the smaller sample size. scores for each case were the dependent variables. Table 1 displays mean DAT AA scores and The ANCOVA was also used to detect differences in GPAs and their standard deviations (SD) for both overall score between the h-PBL D3 and D4 groups. groups. The t-test showed a significant difference The paired t-test was used to test for differences in in DAT AA between TC and h-PBL participants student performance on each case within each of the (p=0.002). There was no difference between the h- curricular groups. Because the individual subject PBL D4 and D3 groups, nor was there a difference data were ordinal, the Mann-Whitney test was used when comparing GPA for all groups. The D3 and D4 to assess curricular differences in performance on class results were therefore combined in subsequent individual subject areas within each case. The Mann- analyses. Based on the finding of a difference be- Whitney test was also used in order to determine if tween the TC and h-PBL groups with regard to DAT, the h-PBL D3 and D4 students performed differently the total scores for the two cases were adjusted for on individual subjects. DAT using ANCOVA. The lack of significant differ- The Institutional Review Boards of Baylor ences observed for GPA or between the D3 and D4 College of Dentistry and Indiana University-Purdue classes required no adjustments. University Indianapolis approved the study, and written informed consent was obtained. Participants Overall Scores
also consented to the release of their DAT AA scores and predental GPAs from the registrar's office to the Participants' total scores were analyzed using descriptive statistics. There were 27 total points available for Case I and 30 points total for Case II. The means were adjusted for differences in DAT AA scores using ANCOVA (Table 2). The ANCOVA dem-onstrated that the h-PBL group performed signifi- Using anticipated values, a power analysis cantly better on Case I than the TC group (p<0.05); revealed that 80 percent power would be maintained the adjusted scored differed by about 2.5 points. On Table 1. Participating students' DAT AA scores and GPAs (mean±SD)

Number of Participants *Significant differences between groups as detected with t-tests Table 2. Mean, SD, and adjusted mean values for Cases I and II total scores

Note: ANCOVA used to adjust total scores for DAT AA scores and test for differences between curricula, where * signifies p<0.05.
Journal of Dental Education ■ Volume 74, Number 10 Case II there was no statistically significant differ- eration. For Case II, TC students scored significantly ence in performance of the h-PBL and TC groups higher in the areas of science comprehension and (p=0.107). There was also no statistically significant difference in performance of the D3 and D4 h-PBL The Mann-Whitney test also showed differ- groups (Case I: p=0.094 and Case II: p=0.138).
ences in performance of the h-PBL D3 and D4 A paired t-test was conducted to determine if groups in the areas of pharmacology (p=0.045) and there was any statistical difference between Case I biochemistry (p=0.037) on Case I. In both instances, and Case II performance within each group (Table the D4 group earned higher scores. 3). The paired t-test revealed that the TC participants did significantly better on Case II than on Case I Instrument Reliability and Validity
(p<0.001); the unadjusted difference was about 3 points. The slightly higher mean performance of 2 Reliability within each case was analyzed with points by the h-PBL students on Case I versus Case Cronbach's alpha. Case I demonstrated a Cronbach's II did not attain statistical significance (p=0.164). alpha score of 0.754. Case II had a score of 0.716. Both of these values indicate strong reliability and indicated the questions were measuring the same underlying concept. Pearson correlation revealed Tables 4 and 5 outline mean rank values and a significant correlation (p=0.001) between Case I significance for each subject in Cases I and II accord- total and Case II total scores (0.376). There was no ing to the Mann-Whitney analysis. For Case I, h-PBL correlation, however, between case totals and DAT students scored significantly higher in the areas of AA scores or GPAs. biochemistry, communication, and hypothesis gen- Table 3. Mean and SD values for Cases I and II total scores with paired t-test significance

*Significant differences within the group based on paired t-tests Table 4. Case I: Mann-Whitney mean ranks and significance values

Diagnosis Treatment *Statistical significance at the p<0.05 level
Table 5. Case II: Mann-Whitney mean ranks and significance values

Sci Comp Anatomy Diagnosis Treatment *Statistical significance at the p<0.05 level October 2010 ■ Journal of Dental Education There were additional factors that could not be controlled for in the design of this investigation. Those factors include differences in course content at This investigation found that in some instances each school and lack of familiarity of the TC students dental students participating in a hybrid problem- with the format of the research instrument—the lat- based learning curriculum were better able than ter of which may have placed the TC students at a students educated in a traditional curriculum to ap- disadvantage. The use of dental students at different ply the basic science knowledge obtained during the stages of their dental education in the h-PBL group first two years of dental school to a clinical scenario. is a flaw of this investigation. The effects of this have There was a statistically significant difference in been addressed earlier in the discussion. Additionally, overall performance on Case I between the TC and because the cases were not completed simultane- ously by participating students, there is a chance The h-PBL D4 and D3 groups also had dif- that information regarding the cases was shared or ferences in performance on Case I in the areas of that additional learning occurred in the time between biochemistry and pharmacology. In this case, the testing. A comparison of scores between early par- D4 students performed significantly better than the ticipants and late participants could have added to the D3 students. Because the D4 students participated in statistical analysis and strength of this study. the investigation near the end of their third year, they Because there was no evidence of a correla- may have acquired more knowledge in these areas tion between students' performance on the clinical throughout the academic year. The D3 students par- cases provided and their DAT AA scores and GPAs, ticipated at the beginning of their third year and may it can be assumed that the instrument used in this not have had an opportunity to learn the information study measures different skills from those measured addressed in Case I in those subject areas. While this by the DAT and traditional scoring with GPAs. Two does not change the final conclusions of the study, an important ideas came out of this: 1) traditional as- even greater and more significant difference between sessment methods may not measure a student's ability the h-PBL and TC groups may have appeared if all of to integrate the biomedical and clinical sciences, and the h-PBL participants had come from the originally 2) the assessment methods used in this investigation sampled class (the D4 group). may be a better way to assess the skills that educators The results of this study also revealed that h- value most. This finding has significant implications PBL students performed significantly better in the for dental education assessment. Academic dental areas of hypothesis generation and communication. institutions, whether employing a traditional cur- This parallels the findings of Patel et al.17,18 Because riculum or some form of PBL, need to utilize appro- of the format used for PBL sessions, it is not surpris- priate assessment tools. The instrument used in this ing that the h-PBL students were better in those areas. investigation may be a good example of a potential PBL students are expected to develop hypotheses assessment tool for dental education. about the provided clinical cases and expound on The question remains as to the validity and fea- them to their group. This usually leads to a discussion sibility of making objective comparisons between two of which hypotheses are more probable than others different educational modalities. With the increased and supporting evidence. Participating in activities effort required by dental institutions to implement like these allows PBL students to cultivate both of a PBL curriculum, a question commonly asked by these skills.
academicians is whether it is any better than the con- Theoretically, students who performed well ventional style of dental education.19 While it may not on Case I should have similar results with Case II, be appropriate to directly compare the two curricula, and the paired t-test would show this. TC students it is surely acceptable to compare the ability of stu- performed better on Case II than Case I, while the dents participating in them. The h-PBL students were opposite occurred for h-PBL students (although not always better than the TC students in applying statistical significance was not attained in the latter). basic sciences to clinical cases in this study, but they This may be a consequence of one group being more were certainly not at a disadvantage either because familiar with the tested subject matter than the other the increased performance of TC students on Case based on curricular differences. II was not statistically significant. Therefore, dental Journal of Dental Education ■ Volume 74, Number 10 schools should consider the benefits of h-PBL type students in a traditional lecture-based curriculum curricula when looking at curricular reform.
based on the attainment of statistically significant The most commonly cited disadvantages of overall scores on one of the two cases presented. a PBL curriculum are cost,19,20 case design,21 and A statistically significant difference in scores was questionable effectiveness of the curriculum as a not found for the second case. whole. The potential need for additional faculty • H-PBL students had increased skills in the areas of members could lead to an increase in spending. communication and hypothesis generation—which Some institutions may also need to address space are necessary as dental professionals interact more issues within their facility to accommodate the small- with other health professionals. group format—which could be costly as well. The • Traditional assessment tools may not be most benefits of increased self-directed learning abilities, appropriate for measuring the ability to integrate increased retention and recall effects,22 and improved basic science information to clinical cases. While performance on national board examinations1 also the instrument used in this study was developed make problem-based learning worth considering. specifically for this investigation, it proved to be Ultimately, the benefits may outweigh the potential effective, valid, and reliable. It could thus serve obstacles and problems.
as a good model for assessing students' ability to It is important to note that this study compared apply basic science to clinical scenarios. students in a traditional curriculum and a hybrid PBL • Additional research comparing traditional, prob- curriculum, not a total PBL curriculum. However, a lem-based learning, and hybrid problem-based hybrid PBL curriculum may prove to be the best of learning curricula could provide additional useful both worlds. It incorporates all of the benefits of a data. Long-term studies would serve as a supple- PBL format yet provides the structure that most PBL ment to this data.
students find lacking. Many students participating in true PBL curricula have a desire for some traditional lectures.23 A hybrid PBL format satisfies this desire. 1. Fincham AG, Shuler CF. The changing face of dental edu- Additional research in this field should be cation: the impact of PBL. J Dent Educ 2001;65(5):406– conducted to determine the impact of problem-based learning on the quality of dental education. The use 2. Barrows HS. The essentials of problem-based learning. J of the same or a similar instrument from this study Dent Educ 1998;62(9):630–3.
3. Field MJ, Jeffcoat MK. Dental education at the crossroads: would also further validate this method for assessing a report by the Institute of Medicine. J Am Dent Assoc the application of basic science to clinical problems. 4. Faggion CM Jr, Tu YK. Evidence-based dentistry: a model for clinical practice. J Dent Educ 2007;71(6):825–31.
5. Pyle M, Andrieu SC, Chadwick DG, Chmar JE, Cole JR, George MC, et al. The case for change in dental education. As dental educators search for ways to meet J Dent Educ 2006;70(9):921–4.
6. Hendricson WD, Andrieu SC, Chadwick DG, Chmar the learning needs of dental students in the new JE, Cole JR, George MC, et al. Educational strate- millennium, curricular innovations become increas- gies associated with development of problem-solving, ingly important. A hybrid problem-based learning critical thinking, and self-directed learning. J Dent Educ curriculum may provide the innovation needed to address the Institute of Medicine's recommendations, 7. Haden NK, Andrieu SC, Chadwick DG, Chmar JE, Cole JR, George MC, et al. The dental education environment. including the need for dental schools to experiment J Dent Educ 2006;70(12):1265–70.
with different models of education, practice, and 8. Vernon DT, Blake RL. Does problem-based learning performance assessment while maintaining the stabil- work? A meta-analysis of evaluative research. Acad Med ity and reliability of the traditional curriculum. The following conclusions and recommendations can be 9. Blake RL, Hosokawa MC, Riley SL. Student performances made based on this study: on Step 1 and Step 2 of the United States Medical Licens-ing Examination following implementation of a problem- • Students enrolled in a hybrid PBL curriculum dem- based learning curriculum. Acad Med 2000;75(1):66–70.
onstrated a greater ability to apply basic science 10. Susarla SM, Medina-Martinez N, Howell TH, Karimbux principles to a clinical scenario when compared to NY. Problem-based learning: effects on standard out-comes. J Dent Educ 2003;67(9):1003–10.
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Journal of Dental Education ■ Volume 74, Number 10

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