Abstract

This study measured the resistance to dislodgment of complete metal crowns when they were fabricated for tooth preparations lacking resistance form. These preparations were modified with four different auxiliary preparation features.

An Ivorine mandibular first molar was prepared on a milling machine with the following characteristics: 20 degrees of total occlusal convergence (TOC), 360 degrees shoulder finish line of 1.0 mm width, and axial wall of reduced height offering no geometric resistance form. The following tooth preparation modifications were studied:

  1. Two proximal grooves (two lingually positioned grooves, one on the mesial and one on the distal surface) (design B) (Figures 6 and 7).
  2. Four proximal grooves (two grooves on the mesial surface & two grooves on the distal surface) (design C) (Figures 11 and 12).
  3. Two proximal grooves (two buccally positioned grooves one on the mesial surface and one on the distal surface) (design D) (Figures 14 and 15).
  4. Twelve degrees TOC versus 20 degrees TOC (design E) (Figure. 16).

Twelve metal dies were fabricated for each tooth preparation design and also 12 complete metal crowns were fabricated and cemented with resin modified glass ionomer cement (Rely-x ®, 3M-ESPE). The resistance form of each specimen was evaluated using a universal testing machine (MTS) by applying a continuous force at a 70 degree angle to the long axis of the samples.

All the data of this study were collected and statistically analyzed in order to determine which modifications significantly enhanced resistance form and also to permit ranking of the modifications in their order of efficacy.

The present experimental study demonstrated that reducing the TOC from 20 to 12 degrees (design E), as well as the addition of 4 proximal grooves (2 grooves on the mesial surface and 2 grooves on the distal surface) (design C) provided resistance form for complete crown preparations that originally lacked it.

There was no significant difference between the control group (design A) and experimental designs B (two lingually positioned grooves, one on the mesial and one on the distal surface), and D (two buccally positioned grooves, one on the mesial surface and one on the distal surface).

LLU Discipline

Prosthodontics

Department

Prosthodontics

School

Graduate Studies

First Advisor

Matthew T. Kattadiyil

Second Advisor

Charles J. Goodacre

Third Advisor

Jay Kim

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 Materials; Dental Alloys; Materials Testing; Tooth Preparation, Prostodontic; Dentures -- methods; Cementation -- methods; Dental Casting Technique; Dental Stress Analysis; Stress, Mechanical

Type

Thesis

Page Count

xi; 56

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

Download

Share

COinS