Thesis (M. Sc.)--University of Manitoba, 1996. / Includes bibliographical references.

Thesis--Göteborg. / Extra t.p. with thesis statement inserted. Includes bibliographical references (p. 43-44).

Thesis (M. Sc.)--University of Manitoba, 1996. / Includes bibliographical references.

Thesis (Ph. D.)--University of Louisville, 1998. / Includes bibliographical references.

Includes bibliographical references. Aims to develop a suitable method to measure friction generated under various orthodontic appliance simulations.

Indiana University-Purdue University Indianapolis (IUPUI) / A study was made to ascertain the effect of heat treatment, at a time-temperature ratio of three minutes at 900 F., on orthodontic 18-8 and Elgiloy steel wire with respect to the followings a) the ability of a vertical loop to resist permanent deformation when subjected to a tensile load; b) the effect of heat treatment on ductility of a steel orthodontic wire; c) the effect of heat treatment on the warpage of a orthodontic wire which has previously been formed. A standardized nine millimeter vertical loop was incorporated in the wire. Weights in increments of 100 grams were suspended from one end of the wire while the other end was firmly held in a vice. Permanent deformation as a result of a given load was determined by the amount of permanent opening of the vertical loop. The force just necessary to produce a permanent opening of the vertical loop is defined as the proportional limit. The ability of Elgiloy to resist permanent deformation due to heat treatment is enhanced as much as 66 percent. On the other hand, Elgiloy heat treatment produces the undesirable side effect of reducing ductility i.e., as high as 77 percent reduction in ductility following heat treatment. Therefore a Elgiloy steel wire cannot be altered in shape to any great extent after heat treatment. Eighteen-eight type 304 steel wire, when subjected to the same treatment, shows an increased ability to resist permanent deformation i.e. a 39 percent increase in proportional limit following heat treatment. It is significant that ductility, as determined by the cold bend test, is not significantly affected by heat treating 18-8 steel wire. The latter phenomena supports the claim of many investigators that 18-8 steel is not capable of a true heat treating transformation and therefore any improvements in elastic properties as a result of heat treatment can be considered to be due to a stress-relieving process. Ductility, as determined by the cold bend test, was found to be a highly variable property. Large variations in ductility were even found in the same feet-length of wire. Both 18-8 and Elgiloy steel wire exhibit this phenomena. Following heat treatment of Elgiloy a reduction in the variability of ductility was noted in all the wires tested. The effect of heat treatment on warpage of a previously shaped orthodontic steel wire was studied by incorporating a right angle bend in the center of a four inch section of wire. After a three week storage at a constant temperature of 98.6m to simulate mouth conditions, the angles were again measured. Any alteration in degrees from the right angle was considered to be indicative of warpage. Heat treated wires were compared to non-heat treated. Heat treatment appears to increase warpage in orthodontic steel wires; however, because of large variations no conclusive results were obtained with respect to this problem.

Indiana University-Purdue University Indianapolis (IUPUI) / The object of this study was the determination of the amount of force exerted by some of the simpler widely-used orthodontic appliances. More specifically, interest was centered on the rate of force delivery, as well as upon the nature of the stresses induced in the various parts of the wires. By using experimentally determined values of the modulus of elasticity and the appliance dimensions the forces and corresponding deflections of these simpler orthodontic structures may be calculated. Theoretical force determinations according to the methods employed in the science of strength of materials were made on the following appliance forms: the finger spring; the simply supported wire; the semicircular wire form; and the U-Shaped arch. Force values and corresponding displacement measurements were made on samples of various sizes of round and rectangular wires. Comparison of these measurements with the calculated values indicated very good agreement.

Indiana University-Purdue University Indianapolis (IUPUI) / This study involved two areas of investigation. First, questionairres were sent to 350 orthodontists in order to determine the types and frequency of methods used to treat contaminated instruments in their practices. Two hundred eighty replies were received. Second, using orthotolidine reagent strips, three commonly-used cleaning methods (alcohol wipe, soap and water scrub, and ultrasonic cleaning) were compared as to their effectiveness in the removal of a potentially dangerous contaminant, blood, from a representative orthodontic instrument, the band pusher. A sample of 15 instruments was tested. The survey showed that a variety of cleaning, disinfecting, and sterilizing procedures were used in various combinations in the practices surveyed. Less than 4.3% of the respondants treated hand instruments -- the group most likely to be contaminated with blood -- in a manner acceptable to various authorities on the subject, such as: The Expert Committee on Hepatitis of the World Health Organization, the United States Institutes of Health, and The Council on Dental Therapeutics of the American Dental Association. Of the three cleaning methods tested, ultrasonic cleaning was the most effective for removing blood from the test instruments, and alcohol wiping was least effective. Both alcohol wiping and soap and water scrubbing left detectable amounts of blood on all instruments tested. Since: a) orthodontic instruments may be contaminated with blood during routine treatment procedures, b) asymptomatic carriers of serum hepatitis may constitute at least 1% of the population, and the viruses of both forms of viral hepatitis may be found in the serum of 5 - 35% of apparently healthy persons, c) as little as .00005 ml of infected blood is capable of transmitting the disease, and d) a high percentage of the sample of orthodontists responding used inadequate methods to treat their instruments, the danger of transmission of viral hepatitis exists in the great majority of orthodontic practices surveyed in this study.

Thesis (M.Sc.D.)--Boston University School of Graduate Dentistry, 1974. Orthodontics. / Bibliography included. / Unilateral distalization of posterior teeth at times plays a significant role in orthodontic therapy. One example of a factor leading to the need for a unilateral distalizing force is a prematurely lost deciduous molar which allows mesial permanent molar migration. / Many biomechanical approaches have been utilized for molar distalization. For instance, several types of extra-oral appliances have been proposed for unilateral molar movement. While some authors suggest that a removable appliance such as the ACCO is the most efficient, (5,6,7), others contend that a modification of the standard Kloehn extra-oral assembly will resolve the problem quite adequately (13, 21,36,40). / Most studies are directed at either a mathematical, mechanical or typodont analysis of the cervical face bow assembly. (8,13,20,21,36,40) Articles covering the ACCO removable appliance mainly outline its construction, indications, and use. (5,6,7) This study was therefore designed to examine and quantitate the actions of the modified cervical traction gear and the ACCO appliance for unilateral molar distalization on a clinical level.

Thesis (M.Sc.D.)--Boston University School of Graduate Dentistry, 1972 (Orthodontics) / Bibliography included. / The present study was undertaken to compare the efficiency of three different biomechanical mechanisms in preserving mandibular molar anchorage. Thirty-five patients were treated with intercanine coil, lip bumper, 9r mandibular cervical traction through the end of cuspid retraction. Midtreatment cephalograms were then taken. Superimposition of these midtreatment cepbalograms with the pretreatment cephalograms provided the author with the net mesial or distal movement of the mandibular first molar in each case. The data obtained from each case was accordingly placed in the appropriate biomechanical group. Each group was then statistically related to one another by means of the Mann-Whitney U Test. It was found that a stastically significant difference existed between lower cervical traction and the intercanine coil. The confidence level obtained (P < .02) indicated that less than two cases out of a hundred had a chance of coming from the same population. This data also showed a mean increase in mandibular anchorage with lower cervical traction ( +.062 mm. gained) indicating that there may be very good possibilities for this system to be used in orthodontic cases when anchorage is of a critical nature.