Schematic, category-based thinking is a common approach to reduce uncertainty. Once the stimulus in question is categorized under a scheme, there is a tendency to look for features that fit the scheme. We have a tendency toward "positive testing" that is, to test instances we think will fit our hypothesis, paying less attention to those that will not (confirmation bias). Schematic, category-based thinking interferes with the process of decision-making in general and in medicine and dentistry in particular. To reduce schematic thinking and to avoid confirmation bias, one must acknowledge their existence. It is the task of dental educators to open the existing schemes and encourage broad, even controversial thinking that will focus on more than one hypothesis.