The Research That Changed How I Looked At Studying for the INBDE: Why Drilling Questions Beats Watching Videos

When I was preparing for the INBDE, I studied the way most people do. Videos, notes, re-reading slides, going back through lecture material. It felt productive. But after I passed, I really felt like the last 10-20% of question drilling is what made all the difference. I started digging into the research on how memory actually works, and it genuinely shifted how I thought about the whole thing and validated what I felt post-exam.

I want to be upfront that this is my perspective, shaped by my own experience and by the research I found compelling. Most of that research comes from medical education and cognitive psychology, not INBDE-specific studies, so take it as food for thought rather than a prescription. It won't resonate with everyone, and there's no single right way to prepare. But if you're putting in serious hours and not feeling confident about where you stand, some of this might be worth sitting with.

The short version is that feeling prepared and actually being prepared can be two very different things, and the way most of us naturally study is better at producing the first one than the second.

Why does passive studying feel effective even when it isn't?

Passive study methods feel productive because fluency mimics mastery, but students who restudy forget 56% of material versus just 13% for those who test themselves.

When you watch a well-produced lecture video and the instructor explains root canal anatomy clearly and confidently, your brain registers “I know this.”

But research suggests that feeling isn't a reliable signal.

Researchers call this the illusion of competence. When material is presented clearly and fluently, your brain confuses the ease of processing with actual mastery. It feels familiar, so it must be learned. Roediger and Karpicke at Washington University put this to the test.¹ Students who repeatedly restudied material rated their learning highest. Students who repeatedly tested themselves rated their learning lowest. A week later, the results were the exact opposite. The restudiers had forgotten 56% of what they'd originally recalled, while the testers had forgotten just 13%.

That gap between how confident you feel and how much you actually retain is where INBDE prep goes wrong for a lot of people.

Why does testing yourself work better than rereading?

Your brain consolidates memory through retrieval, not exposure. A meta-analysis of 272 studies found practice testing outperforms restudying by an effect size of g = 0.67 in real classroom settings.

Your brain consolidates memory through the act of retrieving information, not through the act of receiving it. Every time you pull an answer from memory you're reinforcing that neural pathway in a way that passive review simply doesn't.

This is called the testing effect, and the evidence behind it is fairly consistent across a wide range of subjects and learners. A 2017 meta-analysis of 272 independent experiments found practice testing outperformed restudying by an effect size of g = 0.51, rising to g = 0.67 in real classroom settings.² A comprehensive 2013 review in Psychological Science in the Public Interest evaluated ten common study strategies and gave rereading, highlighting, and summarization low utility ratings. Practice testing and spaced practice were the only two to earn high utility, the only two.³

Karpicke and Blunt's 2011 Science paper compared retrieval practice directly to concept mapping, one of the more involved active study methods, and retrieval practice still won, with 84% of individual students performing better.⁴ The funny thing is that most students had predicted concept mapping would work better. We consistently misjudge which study methods actually work.

How does spaced repetition help you retain what you study?

Without spaced review, roughly 70% of new information is lost within 24 hours. Spacing repetitions near the point of forgetting dramatically extends long-term retention.

The forgetting curve was something I'd heard of but never really taken seriously until I looked at the actual replication data. Research replicating Ebbinghaus' original findings confirmed that under conditions without reinforcement, up to 70% of new information can be lost within 24 hours.⁵ If you cram a category on Monday and don't revisit it until the week of your exam, most of what you learned is already gone.

The solution isn't studying more, it's timing your review strategically. The research suggests that coming back to material just before you'd forget it locks it in far more effectively than reviewing it while it's still fresh. A 2026 meta-analysis in The Clinical Teacher analyzing over 21,000 learners found spaced repetition produced a large effect size of SMD = 0.78 compared to standard studying.⁶ A randomized controlled trial with over 26,000 practicing physicians found spaced repetition produced scores of 58% versus 43% for non-spaced controls.⁷

And this isn't just medical education theory. A 2024 RCT published in the Journal of Dental Education found that dental students using spaced repetition via a mobile app significantly outperformed lecture-only controls on knowledge retention.⁸ Same profession, same kind of exam.

Do practice questions actually predict board exam performance?

Practice question completion, not total study hours, is the single strongest modifiable predictor of board exam scores across multiple medical education studies.

Again, I want to be transparent here that these studies come from medical board research rather than the INBDE specifically. But the underlying pattern felt consistent enough that it felt relevant. Giordano, Hutchinson, and Peppler (2016) found that QBank percentage correct correlated strongly with USMLE Step 1 scores (r = 0.622), and for every percentage point improvement on practice questions, students saw a measurable increase in their board score.⁹ What didn't correlate? The number of days studied.

Drake, Phillips, and Kovar-Gough (2021) found the same pattern for Step 2: after controlling for everything else, only completing practice questions remained independently predictive of performance. Passive review resources showed no independent benefit.¹⁰ Baños et al. (2018) found that when an entire medical school cohort received question bank access, question bank utilization was a stronger predictor of outcomes than MCAT scores.¹¹

The INBDE is testing your ability to apply knowledge under pressure, not recognize it from a familiar slide deck. That principle translates regardless of the exam name on the cover.

Does focusing on weak areas speed up exam preparation?

Adaptive practice targeting weak areas achieves the same effect size as one-on-one human tutoring (d = 0.76), moving students from the 50th to the 75th percentile.

In my own INBDE prep, some of my biggest gains came not from studying more overall, but from just being honest about where I was struggling and drilling those areas specifically.

The research backs this up. VanLehn's 2011 review in Educational Psychologist found that adaptive practice systems achieved an effect size of d = 0.76, close to the d = 0.79 found for one-on-one human tutoring.¹² Kulik and Fletcher's meta-analysis found adaptive practice raised scores by a median of 0.66 standard deviations, enough to move a student from the 50th to the 75th percentile.¹³

The idea here is that if you're spending equal time on periodontics (where you're scoring 85%) and pharmacology (where you're scoring 40%), you're leaving real points on the table. Knowing where your gaps are, and actually going after them, is one of the most effective things you can do.

Should you practice with a timer when studying for the INBDE?

Learn concepts without time pressure first, then drill under timed conditions to build the test-taking fluency the INBDE demands.

Timed practice is a tool. It isn’t necessarily what you should start with, but it’s a goal to work up to. Research shows that time pressure during the learning phase is actually counterproductive, one study found it completely prevented the relational learning gains students otherwise achieved.¹⁴ Rushing through material you haven't consolidated yet doesn't build fluency; it just builds anxiety.

But the reality is still that the INBDE gives you roughly 90 seconds per question. If you've never practiced retrieving answers under a time constraint, that pressure will cost you on exam day. Not necessarily because you don't know the material, but because you haven't trained your brain to access it quickly.

The pattern the research supports is that we should learn and understand concepts in a low-pressure environment first. Then shift to timed practice to build the speed and confidence that the actual exam requires.

What does effective INBDE study actually look like?

Drill questions consistently, on a spaced schedule, with focused attention on weak areas. Total hours studied and specific resources used are secondary.

This was my takeaway from all of the above, and how I’d change my methods if I were to take the exam again. It's simpler than the prep industry sometimes makes it seem.

If I was to go back in time and define a 4-hour study block for myself, here's how I’d spend it based on what the research actually supports:

Hour 1: Warm-up with review. I’d start by going back over questions I got wrong in my last session. Not rereading notes, but actively re-testing yourself on those specific items. This is spaced active retrieval doing its job. If I got a pharmacology question wrong two days ago, I’d pull up that explanation and then close it and try to reconstruct it from memory.

Hours 2–3: New drilling. This is the bulk of my session. I’d run a focused question set in my weakest subject - not a mixed bag, not your best. I’d target the area where my accuracy is lowest. I’d read every explanation whether I got it right or wrong.

Hour 4: Timed finish. I’d end the session with a timed mixed set. This isn't about learning new material, it's about practicing the mental state of the actual exam. I’m looking to build the fluency to retrieve quickly under pressure.

How should that change depending on how often you're studying?

If you're studying 6 days a week, your sessions can obviously be more focused. Each day can target a single subject in depth, and your review at the start of each session naturally handles the spaced repetition. Yesterday's misses become today's warm-up, and you have enough frequency that the forgetting curve works in your favor.

If you're studying 2 days a week, you need to be more intentional about spacing. With longer gaps between sessions, more forgetting happens in between. Which actually isn't all bad, since retrieving harder is more valuable than retrieving easy. But it means your warm-up review needs more time, and you should lean harder on flagging and tagging weak questions during each session so you have a clear queue ready when you come back. With only two sessions a week, you can't afford to start each one figuring out where you left off.

Either way, the core principle doesn't change: the drilling is the studying. Everything else supports it.

A note from me

I passed the INBDE on my first attempt. When I look back at what made the difference, I don’t believe it was the hours I logged, but rather how I spent them (especially towards the end). Drilling questions relentlessly, reviewing the ones I missed, and coming back to my weakest areas again and again.

That experience is a big part of why my husband Mike and I built Blip Dental. Pretty much all of the features of the platform revolve around the idea that active retrieval and spaced repetition beat out passive learning any day.

The first 50 questions are free, and you get 10 questions a day for free after that (fully-explained).

Frequently asked questions

Is watching lecture videos enough to pass the INBDE? Research consistently suggests passive learning, including video lectures and rereading, produces significantly lower retention than active retrieval practice. Students who rely primarily on videos often feel well-prepared but perform worse on delayed tests than students who spent the same time drilling practice questions.

How many practice questions should I do for the INBDE? There's no published INBDE-specific threshold, but medical board research suggests that students who complete at least 2,000 practice questions perform measurably better than those who complete fewer. The broader pattern — that question volume correlates more strongly with exam scores than total hours studied — is consistent across multiple studies.

What is active recall and why does it help with board exams? Active recall is the practice of retrieving information from memory without looking at the source material, most commonly through practice questions or flashcards. It outperforms passive review because the act of retrieval itself is what strengthens the memory. A meta-analysis of 272 experiments found an effect size of g = 0.51 favoring retrieval practice over restudying.

What's the best way to use practice questions when studying for the INBDE? The research supports three principles: space your sessions over days and weeks rather than cramming; prioritize the categories where your accuracy is lowest; and once you're comfortable with the material, practice under timed conditions to build test-taking fluency.

Does spaced repetition work for dental board exam preparation? Yes. A 2024 randomized controlled trial with dental students found spaced repetition using a mobile flashcard app produced significantly better retention than lecture-only study. A 2026 meta-analysis of over 21,000 medical learners found a large effect size (SMD = 0.78) for spaced repetition versus standard studying.

References

1. Roediger, H. L., & Karpicke, J. D. (2006). Test-enhanced learning: Taking memory tests improves long-term retention. Psychological Science, 17(3), 249–255.
2. Adesope, O. O., Trevisan, D. A., & Sundararajan, N. (2017). Rethinking the use of tests: A meta-analysis of practice testing. Review of Educational Research, 87(3), 659–701.
3. Dunlosky, J., Rawson, K. A., Marsh, E. J., Nathan, M. J., & Willingham, D. T. (2013). Improving students' learning with effective learning techniques. Psychological Science in the Public Interest, 14(1), 4–58.
4. Karpicke, J. D., & Blunt, J. R. (2011). Retrieval practice produces more learning than elaborative studying with concept mapping. Science, 331(6018), 772–775.
5. Murre, J. M. J., & Dros, J. (2015). Replication and analysis of Ebbinghaus' forgetting curve. PLOS ONE, 10(7).
6. Maye, M., et al. (2026). The effectiveness of spaced repetition in medical education: A systematic review and meta-analysis. The Clinical Teacher.
7. Price, D., et al. (2025). The effect of spaced repetition on learning and knowledge transfer in a large cohort of practicing physicians. Academic Medicine.
8. Santhosh, S., et al. (2024). Effectiveness of spaced repetition learning using a mobile flashcard application among dental students: A randomized controlled trial. Journal of Dental Education.
9. Giordano, C., Hutchinson, D., & Peppler, R. (2016). A predictive model for USMLE Step 1 scores. Cureus, 8(9).
10. Drake, T., Phillips, J., & Kovar-Gough, I. (2021). Exploring preparation for the USMLE Step 2 exams to inform best practices. PRiMER, 5.
11. Baños, J. H., Pepin, J., & Van Wagoner, T. (2018). Class-wide access to a commercial Step 1 question bank improves academic performance. Academic Medicine, 93(3).
12. VanLehn, K. (2011). The relative effectiveness of human tutoring, intelligent tutoring systems, and other tutoring systems. Educational Psychologist, 46(4), 197–221.
13. Kulik, J. A., & Fletcher, J. D. (2016). Effectiveness of intelligent tutoring systems: A meta-analytic review. Review of Educational Research, 86(1), 42–78.
14. Chuderski, A. (2016). Time pressure prevents relational learning. Learning and Individual Differences, 49, 361–365.

Silppa Harrison is an endodontist and co-founder of Blip Dental. She passed the INBDE on her first attempt and writes about board exam preparation, evidence-based learning, and the science of memory.