Place breadcrumbs in a large heavy-duty zip-top plastic bag. Dip chicken in milk; add chicken to bag. Seal and shake to coat.
Heat oil in a large nonstick skillet over medium heat. Add chicken; sauté 7 minutes or until done.
Fill each pita half evenly with lettuce, tomato, and chicken. Drizzle each half with 2 tablespoons dressing.