Indiana University-Purdue University Indianapolis (IUPUI) / The present study was designed to test the tensile bond strength of two new bracket base designs and compare the results with those of the study by Higgins using Ormesh brackets. It was hypothesized that the visible increase in surface roughness of the two new bracket bases over the conventional (Ormesh) mesh would increase the tensile bond strength of the bracket. Sixteen DuraLingual mesh brackets and the acid-etched bracket bases were fabricated and bonded to human maxillary bicuspid teeth with a Bis-GMA compound adhesive as described by Higgins. After 24 hours, the bases were subjected to tensile bond strength testing until failure in tension and 10 brackets tested from each group were used to calculate the results. The following results were recorded: (1) The mean tensile bond strength of DuraLingual mesh and acid-etched bracket bases were significantly greater than the Ormesh wire mesh. (2) The mean tensile bond strength of the acid-etched base was significantly greater than the DuraLingual mesh. The visually apparent surface roughness and intricate microscopic voids and pits created by electrolytically-etching a smooth bracket base surface may have contributed to greater mechanical retention in this bracket compared to a smooth wire mesh bracket base (Ormesh) and a cast mesh (DuraLingual).

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.

Magister Scientiae Dentium - MSc(Dent) / Background: A close marginal adaptation between the tooth and the bracket base is important since it provides the space for the adhesive. In order to withstand and resist the orthodontic forces exerted as well as everyday forces like mastication and oral hygiene practices, the adhesive material to the bracket must have sufficient sheer bond strength. This means that no deformations, cracks, or fractures should occur within the bracket material and adhesive (Keizer et al., 1976). Aim: The aim of this study was to determine the accuracy of the marginal adaptation of the bracket bases of seven different brands of orthodontic brackets to the tooth surface of a right upper first premolar (ie. Abzil, Forestadent, GAC, Gemini, IMD, Ormco and Victory LP). Method: This research was an in vitro, descriptive comparison study. Fifteen caries and crack free intact human first premolars were used. The teeth were obtained from patients requiring extractions for orthodontic purposes and collected from Tygerberg Oral Health Centre. A convenience sample method was used, where whenever an upper caries free premolar was extracted, the parent was asked if the tooth could be used for this study and consent was obtained. The crowns of the 15 teeth were cleaned and polished with pumice and rubber cups for 10 seconds (as the clinician would do prior to bracket cementation). The same 15 teeth were used with the seven different brands of brackets in order to establish a comparison of the adaptability of the brackets. The brackets were placed at a set orthodontic prescription of 4mm (measured from the slot area of the bracket to the tip of the buccal cusp of the tooth) on the upper first premolars. After bracket placement, the dontrix gauge was applied to the bracket to engage the slot area. The brackets were held in place with a constant force of 0.70 Newton (N) by the dontrix gauge. This allowed for reproducibility for the seven brackets with all fifteen teeth. In order to assess the space between the brackets and the teeth no adhesive was used. The space between the margins of the bracket and tooth interface was viewed under the Stereomicroscope (Carl Zeiss microscope, Zeiss Stemi508) at 50 times magnification. A two way mixed measures ANOVA was run to determine whether there were differences between the seven brackets placed at six points on the tooth surface. Results: GAC had the smallest overall mean measurement between bracket base and tooth surface followed by Ormco and Gemini respectively. Abzil had the largest overall mean measurement for the six points around the bracket

Thesis (M.S.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains x, 155 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 116-124).

Thesis (M.S.)--University of Michigan, 1984.

Thesis (M.S.)--University of Michigan, 1972.

Thesis (M.S.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains xii, 290 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 186-196).

Thesis (M.S.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains ix, 204 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 136-139).