Formal Usability Evaluation of a Touch-Based Tooth Charting Application

Adam Sorenson
Adam Sorenson
University of Wisconsin

Sorenson AD, Schwei KM, Mahnke AN, Acharya A.
Biomedical Informatics Research Center

Research area: Dental Informatics 

Background: Clinical computing in dentistry is increasingly prevalent. Studies demonstrate a need for intuitive clinical information systems in dental practices. The dental informatics team at Marshfield Clinic had previously developed a prototypical "Intelligent Tooth Charting System" (iTooth) for tablet use, enabling dental providers to record tooth status using touch-based gestures. The purpose of this study was to evaluate the usability of iTooth through feedback from dental providers.

Methods: Nine participants were recruited, including dentists, hygienists, and dental assistants. During one-on-one sessions, the moderator gave participants basic instruction on iTooth. Participants were video and audio recorded as they completed typical tooth charting tasks using a think-aloud protocol. Pre- and post-test interviews and surveys measuring the system usability scale (SUS) score and Net Promoter Score (NPS) were administered. Participants completed a desirability word selection exercise. Sessions were reviewed and analyzed using Morae Manager (TechSmith).

Results: iTooth had a SUS score of 67.75 and a NPS of zero. Task time varied from 10 to 120 seconds. Average percent completion without assistance varied from 10% to 100% among all tasks. Usability problems were identified, including participants’ inability to locate a particular icon (78% of participants), confusion resulting from charting statuses (44% of participants), and 50% recognition failure for the root canal gesture. Most commonly selected words describing the system were "efficient," "useful," "usable," and "new." Conclusions: A NPS of zero is considered neutral and a SUS score of 67.75 translates to the grade of "C", meaning the current prototype has average usability. Results will direct iTooth’s future development, improving usability and functionality. Suggested improvements include revised icon placement for easier location, grouping of "pathology" and "treatment planned" charting statuses, and enhanced symbol recognition. Feedback illustrated that iTooth may be an exciting alternative to traditional mouse-computer interfaces in the future of dental charting.