per·i·o·don·tics 
(pĕr′ē-ə-dŏntĭks)
(pĕr′ē-ə-dŏntĭks)n. (used with a sing. verb)
The branch of dentistry that deals with the diagnosis and treatment of diseases and disorders of the gums.
per′i·o·dontic, per′i·o·donti·cal adj.
per′i·o·dontist n.