Abstract

In order to quantitate initial tooth movement in response to forces applied to the tooth crown, an instrument for intraoral use has been developed. The photomicrometer consists of nine photosensitive cells mounted in an assembly of two layers. Eight of the cells were mounted to form X and Y axes, top layer and bottom layer, to measure horizontal movements. The ninth cell was mounted in the center of the bottom layer and was used for alignment and for measurements in the Z or vertical axis. The photocell assembly was approximately 10 mm diameter and 6 mm high. This assembly when mounted on a tooth had zero impedance to movement. A light source was mounted over the cell assembly supported from a bracket mounted on a removable palatial appliance.

The light was masked such that one half of each of the X and Y cells were in the mask shadow. The opposing X or Y cells of each layer were connected in a bridge configuration which contained ten turn potentiometers. It was possible to align the cell assembly and masked light so that all four systems could be balanced to null at one time.

The sensitivity of the system was such that movements of a few microns caused a disbalance of the bridge and presented an error signal which when recorded on a strip chart recorder could then be read in millimeters.

It was possible by use of two layers of cells to distinguish between linear and tipping movements in the X and Y axes. The Z axis cell functioned by merit of the inverse square law for intensity of a light beam.

Photomicrometer tests were made on a cuspid tooth using applied forces of 28 to 168 grams. The resultant movement response was measured and recorded on a strip chart recorder. The results indicated that after a force had been applied, the tooth tested would return to its original position in two stages. Also it would intrude in response to forces up to 56 grams as much as it would extrude to equal forces.

It was hoped that a resistor distribution pattern in initial response to an applied force could be made, from information gathered with the photomicrometer. It was felt that such a pattern of initial response would be helpful in designing orthodontic appliances.

LLU Discipline

Orthodontics

Department

Dentistry

School

Graduate School

First Advisor

Howard W. Conley

Second Advisor

Edwin M. Collins

Third Advisor

John P. DeVincenzo

Fourth Advisor

J. Mailen Kootsey

Fifth Advisor

Ivan R. Neilsen

Degree Name

Master of Science (MS)

Degree Level

M.S.

Year Degree Awarded

1968

Date (Title Page)

6-1968

Language

English

Library of Congress/MESH Subject Headings

Dental Instruments

Type

Thesis

Page Count

vii; 83

Digital Format

PDF

Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Collection

Loma Linda University Electronic Theses and Dissertations

Collection Website

http://scholarsrepository.llu.edu/etd/

Repository

Loma Linda University. Del E. Webb Memorial Library. University Archives

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