Based on a thesis submitted to the Faculty of the Graduate School, State University of New York at Buffalo, New York, in partial fulfillment of the requirements for the M.S. degree.

This investigation was supported in part by USPHS research grant 5 RO1 DE0271302 from the National Institute of Dental Research, National Institutes of Health, Bethesda, Maryland, and General Research support Grant SO1 FR0533008 to the School of Dentistry, State University of New York at Buffalo, New York.

Based on a thesis submitted by H. Mitani in partial fulfillment of the requirements for the Master of Science degree, Graduate College, University of Illinois, 1969.

This study was supported in part by Research Grant D-1468 from the National Institute for Dental Research, U. S. Public Health Service.

Given at the seventeenth biennial meeting of the Angle Society, New Orleans, October, 1967.

From the Division of Dental Health, National Institutes of Health, San Francisco, California.

From the Department of Orthodontics, School of Dentistry, University of Washington. This study was supported by Public Health Serviae Training Grant DE-00238-01.

*From a thesis in partial fulfillment of the requirements for the degree of Master of Dental Science, Tufts Univ. School of Dental Medicine.

Read before the Tufts Association of Orthodontists, May 1968.

This paper is based on a portion of the M.D.S. thesis submitted to the University of Adelaide, South Australla.