Understanding factors that contribute to adverse events (AE) is key to preventing them from recurring. This study used an electronic trigger tool to identify potential AE in two dental practices. Of 439 charts reviewed, 13% contained at least one AE. The most common AE was post-procedural pain; the expert panel reported 21% of those AEs were preventable. Person-related factors (e.g., supervision, fatigue) were the most common contributing factors.