Medicine and Health Sciences Commons^™

An In Vitro Study Comparing The Conventional Step-Back Instrumentation Technique To A Combination Step-Back/Ultrasonic Technique, James A. Eberhardt

Loma Linda University Electronic Theses, Dissertations & Projects

Cleaning and shaping the root canal system is an important phase of endodontic therapy, and must be performed thoroughly and completely if successful root canal therapy is to be expected. A number of investigators have compared different methods of cleaning and shaping of the root canal system. The purpose of this study was to compare the effectiveness of the conventional step-back technique with that of a combination step-back/ultrasonic technique. This combination technique is a modification of the conventional step-back technique using an ultrasonic instrument alternately with hand instrumentation. Utilizing 40 canals from extracted human mandibular molar teeth with a curvature …

Development Of Periapical Lesions In Immunosuppressed Rats, Phillip A. Waterman Jr.

Loma Linda University Electronic Theses, Dissertations & Projects

The pathogenesis of periapical lesions is the interaction of the oral flora with the existing host defenses. The role of bacteria has been established in endodontic disease but the contribution of the host defenses in periapical lesion formation is less clear. The purpose of this study was to compare periapical lesion development in immunosuppressed rats with that in normal rats. Thirty-five, eight-week old Sprague-Dawley rats were equally divided into seven groups. Groups 1, 2, and 3 were given weekly injections of Cytoxan, an immunosuppressive agent. Groups 4, 5, and 6 received no immunosuppressive therapy. Group 7 served as a control, …

Antibacterial Effects Of Various Endodontic Irrigants And Medicaments On Selected Anaerobic Bacteria, Patrick K. Ohara

Loma Linda University Electronic Theses, Dissertations & Projects

This study was undertaken to determine the antibacterial effects of various endodontic irrigants and medicaments against six selected anaerobic bacteria. In part 1, the organisms were mixed separately with dilutions of six irrigants in tubes containing fluid thioglycolate broth and allowed to remain in contact for specific time periods before being evaluated for growth. In part 2, the vapors of six medicaments were tested using agar plates streaked with the bacteria.

For part 1, the six irrigants were ranked as to their ability to inhibit bacterial growth. Statistical analysis showed that chlorhexidine and hydrogen peroxide were significantly more effective as …

Retrofilling Materials : The Effects Of Two Setting Times On The Degree Of Dye Leakage Of Retrograde Filling Materials, Robert K. Higa

Loma Linda University Electronic Theses, Dissertations & Projects

Sealing of the root canal system is usually accomplished by the conservative endodontic approach. Cases where it is impossible to treat nonsurgically are usually treated surgically by an apicoectomy and retrofill. There is a lot of controversy in the literature over which retrofilling material is closest to ideal. Presently, the most popular materials seem to be Amalgam, Super EBA, and IRM. For this reason, these materials were chosen for this study to evaluate the leakage potential at two different time intervals to see if setting time of the material had any influence on the amount of leakage.

Seventy extracted single …