The dentist is completing root canal therapy on a lower right lateral incisor tooth. Which instrument is likely to be passed to the dentist to insert the filling material into the canal?

The rotary paste filler is specifically designed for the precise delivery of filling material into the root canal system during endodontic procedures, such as root canal therapy. These instruments utilize a rotating mechanism to efficiently fill the canal with materials like gutta-percha or other sealants. Their design allows for an even distribution of filling materials, ensuring that all spaces within the canal are adequately filled, which is critical for successful endodontic treatment and preventing future infection.

In this context, it is important to understand the purposes of the other instruments. A barbed broach is primarily used for the removal of pulp tissue and cleaning the canal, while Mitchell's trimmer is an instrument used for contouring and finishing dental restorations, particularly in the preparation of cavity margins. A periosteal elevator is intended for lifting the periosteum from bone during surgical procedures, not for filling canals. Therefore, the rotary paste filler is the most appropriate instrument to facilitate the filling of the canal with the necessary material during root canal therapy.