Read before the University of Illinois Orthodontic Society, Chicago, March, 1964.

Read March, 1964, University of Illinois Orthodontic Society meeting.

From the departments of Crown and Bridge, and Dental Materials, Marquette University School of Dentistry.

Portions of this paper were taken from a thesis by one of the authors (JRS) submitted to the faculty of the Graduate School, Marquette University, in partial fulfillment of the requirements for the degree of Master of Science.

This study was supported in part by Research Grant DE 01057 and Training Grant DT-22 from the National Institute of Dental Research, U.S. Public Health Service.

From the Orthodontic Department, Howard University.

This study was financed in part by U.S. Public Health Service Grant Number DE 00331-07.

From the department of Oral Pathology, University of Illinois.

This study was supported in part by Public Health Service Grant DE-00968 from the National Institute for Dental Research, N. I. H. Bethesda, Maryland.

An abstract version of the author's unpublished Master's Thesis, University of Tennessee, 1962.