。
She goes to the dentist every other day.
Literal
She [topic-は] day [at intervals of-おきに] dentist [to-に] is-attending.
通う ('to commute / attend regularly') is the standard verb for going somewhere repeatedly as a routine — school, work, the gym, a dentist, a doctor. The に marks the destination. ~ている here shifts to the habitual-action reading on this activity verb — 'is regularly attending,' an ongoing pattern of visits. 歯医者 ('dentist,' literally 'tooth-doctor') is the everyday word; the formal alternative 歯科医 (read しかい) appears on signage and official documents. Going to the dentist every other day suggests an active treatment course — Japanese dentistry famously breaks treatments into many short visits rather than long single sessions, partly due to insurance reimbursement patterns.