Abstract

This study compared the effectiveness of six different auxiliary preparation elements on the resistance to lateral dislodgment of complete crown preparation lacking resistance form.

An ivorine mandibular first molar was prepared with the following characteristics: 20° TOC, 360° shoulder finish line of 1.0 mm width and axial wall of reduced height offering no geometric resistance form (Group A: control). Preparation modifications were Group B: MD grooves, Group C: BL groves (sic), Group D: MDBL grooves, Group E: MD small boxes, Group F: MD large boxes and Group G: 8° TOC at the cervical 2 mm of the axial walls. Ten metal dies were obtained for each preparation design and complete crowns were fabricated and cemented. The resistance to dislodgment of each specimen was evaluated by applying continuous lingual to facial force at 70° until cement failure.

The addition of MD grooves, BL grooves, MDBL grooves, MD small boxes and 8° TOC provided resistance form to complete metal crown preparations originally lacking of geometric resistance form. The addition of MD large boxes did not increase statistically significant the resistance form. A sequential ranking of preparation modification effectiveness for the experimental groups can be established as : G, B-E-D, C, F-A.

CONCLUSIONS :

1) This study introduces the concept of qualitative resistance form (QRF) and establishes a direct relationship between the quality of the crown preparation modification and the quantity of resistance form value obtained on the laboratory test.

2) The reduction of total occlusal convergence at the cervical 2 mm of the axial walls from 20° to 8°, as well as the addition of grooves and small boxes parallel to the long axis of the preparation provided resistance form to complete crown preparations that originally lacked it.

3) MD grooves can be considered as the preparation modification of choice to provide resistance form on preparations of short clinical crowns. It does not take additional unnecessary tooth structure, maintains the structural integrity of the tooth, provides high quantitative resistances form values (2nd rank) and it takes less chair time and is not as technique sensitive as the other preparation modifications evaluated.

LLU Discipline

Prosthodontics

Department

Prosthodontics

School

Graduate Studies

First Advisor

Mathew Kattadiyil

Second Advisor

Wayne Campagni

Third Advisor

Charles Goodacre

Fourth Advisor

Alejandro Kleiman

Fifth Advisor

Jose Torres

Degree Name

Master of Science (MS)

Degree Level

M.S.

Year Degree Awarded

2009

Date (Title Page)

6-2009

Language

English

Library of Congress/MESH Subject Headings

Crowns; Dental Alloys; Materials Testing; Tooth Preparation, Prosthodontic; Dental Prosthesis Design; Dental Prosthesis Retention -- methods; Dental Casting Technique; Dental Models; Post and Core Technique; Cementation -- methods; Stress, Mechanical; Dental Stress Analysis; Comparative Study

Type

Thesis

Page Count

xi; 85

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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