Data from whole-class discussions in Dutch upper primary school show that teachers occasionally explicitly take downgraded epistemic stances through epistemic disclaimers such as 'ik weet het niet' (English: "I don't know (it)"), which contrasts with their institutionally assigned epistemic authority. In the current study, we have collected turns in which such epistemic disclaimers occur, and analysed them using conversation analysis. In our analyses, we focused on the positions of the turns in which epistemic disclaimers occur, and on the varying ways in which these turns influence the subsequent course of interaction. We have found that teachers' epistemic disclaimers occur in initiating turns, facilitating student participation, but also in responsive turns. The latter vary in the extent to which they facilitate participation, ranging from facilitating student participation in a similar way to the initiating turns, to blocking further student contributions altogether. This study furthermore demonstrates that teachers employ epistemic disclaimers to navigate two teacher roles, namely those of a teacher with epistemic authority, and of a facilitator of whole class-discussions.