Read before the Southern California Component of the Angle Society, May 1976.

From Departments of Oral Surgery, Pedodontics, Orthodontics and Dental Roentgenology, Institute of Dentistry, University of Helsinki.

From the Department of Orthodontics, University of Oslo, Oslo, Norway.

From the Department of Orthodontics, University of Connecticut Health Center, Farmington, Connecticut.

This study was supported by N.I.H. grant No. DE00136.

Read at the February, 1977 meeting of the Southern California Component of the Angle Society.

Based on a master's thesis at the Ohio State Univ., March 1974.

From the Dept. of Orthodontics, Faculty of Cont. Medical Education, Dental Division, Tel-Aviv University, Tel-Aviv, Israel.

From the Government Dental College and Hospital, Ahmedabad-380016, Gujarat, India.

Given before the Univ. of Illinois Orthodontic Alumni Society, March 1976.