Page numbers are currently added to the ToC as a single field. I believe folks commonly add them like so: "12-34". However, a number of areas where page numbers are required metadata need these numbers provided individually, as firstPage, lastPage metadata types (eg. CrossRef: see Bug 5279; and Google Scholar; see Bug 6956). 

I think the solution is two-fold:

1) the Page Number field in the editor's ToC should be split into two (firstPage, lastPage) fields;

2) any values that are already in the articles.pages table cell that include a dash should be split. 

I'm not particularly sure as to the best way to implement these changes: maybe add two new columns to the articles table (ie. first_page, last_page), split the article.pages column values if applicable on upgrade, and subsequently delete article.pages?