sentences:  Delta Sigma Delta
  
  Delta Sigma Delta (ΔΣΔ), founded on November 15, 1882, is the oldest and largest of the international professional dental fraternities, pre-dating Xi Psi Phi (1889), Psi Omega (1892) and Alpha Omega (1907).Two dental students, Lou Mitchell and Chas Howard, at the University of Michigan School of Dentistry in Ann Arbor were invited to join Nu Sigma Nu, a medical fraternity.