Indiana University-Purdue University Indianapolis (IUPUI) / This investigation was designed to compare the force (grams) required to overcome a simulated cuspid retraction assembly capable of three dimensional control during the retraction process. It was hypothesized that a significant difference in the mean retraction values exists between the newer orthodontic alloys of Nitinol, Beta-Titanium, as well as Stainless Steel. One hundred eighty bracket and archwire combinations were examined as follows: Sample # Wire Cross-section Wire Material 30 .016”x.022” Stainless Steel 30 .017”x.025” ” 30 .016”x.022” Nitinol 30 .017”x.025” ” 30 .016”x.022 Beta-Titanium (TMA) 30 .017”x.025” ” A statistically significant difference was shown to exist between all six groups examined regarding the variables of wire size and wire material. The statistical analysis revealed that increasing rectangular archwire cross-sectional size from .016"x.022" to .017"x.025” rectangular wire when simulating canine retraction using an .018" slotted Lewis bracket will lead to significantly greater functional forces. The analysis of wire materials indicated that a significant difference (p=.01) exists between rectangular Beta-Titanium (TMA), Nitinol, and stainless steel during simulated cuspid retraction utilizing a narrow .018" Lewis bracket ligated with A-lastik ligatures. The least frictional force was observed with the .016"x.022" stainless steel test cells. The largest frictional force was found in the .017”'x.025" Beta-Titanium retraction specimens. Nitinol revealed force data intermediate between stainless steel and Beta-Titanium. The maximum resistance assembly developed 2.3 times the minimum frictional force observed. The mean grams of frictional force within these test cells ranged from 55.03 grams for the .016"x.022" retraction assembly to 132.68 grams for the .017"x.025" Beta-Titanium assembly. A topographical scanning electron microscope survey of the brackets and archwires utilized was included to provide qualitative insights into the quantitative results described.

Thesis (M.Sc.D.)--Boston University School of Graduate Dentistry, 1972. (Orthodontics) / Bibliography included. / The present study was undertaken to document the incidecnce of the relapse phenomena taking place up to two years after completion of active orthodontic therapy. This paper was limited specifically to the post treatment changes of the mandibular plane. The study was carried out on the records of thirty-six patients treated in the orthodontic clinic at Boston University School of Graduate Dentistry. Original, final, and two year post treatment cephalograms, pano-graphs, and study models were evaluated and compared for each patient. Observations of the compiled data revealed that twelve of the thirty-six patients showed a decrease in the mandibular plane angle during treatment, while ten patients showed an increase. Further analysis of the results revealed that the majority (70%) of the patients with the increased mandibular plane angle showed a decrease during the retention period, reverting back to or toward pretreatment values. Of the twelve patients experiencing a decrease during treatment, the post treatment results were more varied, and no definite trends could be observed. Further study is needed to determine if an increase in the mandibular plane angle during orthodontic treatment is nonphysiologic and, therefore, more susceptible to relapse.

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.

Thesis (M.S.)--University of Louisville, 1997. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--University of Southern California, 1996. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (M.S.)--University of Louisville, 1997. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (doctoral)--Westfälische Wilhelms-Universität, Münster, Germany.

Thesis (doctoral)--Westfälische Wilhelms-Universität, Münster, Germany.

Thesis (doctoral)--Friedrich-Wilhelms-Universität, 1978.

Thesis (doctoral)--Friedrich-Wilhelms-Universität, 1978.