Just finished 2 more books I found worthwhile:

McGurk, M. & Renehan, A. (2001). Controversies in the management of salivary gland disease. (ISBN: 0-19-263278-7)
and
Strafford, N. & Waldron, J. (1989). Management of oral cancer. (ISBN: 0-19-261609-9). This book is a bit older, and may be somewhat dated re. radiation therapy, but nevertheless offers generally useful information on treatment, as well as details on a variety of oral tumors.