This advice-column-style blog for SLPs was authored by Pam Marshalla from 2006 to 2015, the archives of which can be explored here. Use the extensive keywords list found in the right-hand column (on mobile: at the bottom of the page) to browse specific topics, or use the search feature to locate specific words or phrases throughout the entire blog.
Q: Do you know if chewing tools are effective in correcting open mouth posture in a 2-year-old? Is there any research on this?
The question reveals that you are assuming too much one-to-one correspondence between methods of oral stimulation and results.
Chewy tools are designed to facilitate up-and-down jaw movements, and to increase the amount of time a client keeps his jaw in the “up” position. That is all they will do.
To assume that chewing on a chewy tool or toy automatically will establish correct oral rest position is too much extension of the idea. Oral rest posture entails far more than a simple analysis of jaw position. It also incorporates lip position, tongue position, head position, and status of the entire upper respiratory system. Therefore, a chewy tube, by itself, will not establish correct closed-mouth oral rest position any more than teaching a single vocabulary word will remediate a language deficit.