Indiana University-Purdue University Indianapolis (IUPUI) / This study evaluated the feasibility of bonding brackets to porcelain for orthodontic purposes by measuring and comparing tensile strengths of five silane-based adhesive systems. Each adhesive system bonded mesh pad brackets to 10 glazed and 10 deglazed metal-ceramic crowns and the specimens were then thermocycled between 16 degrees and 56 degrees for 2500 cycles. Clinically relevant bond strengths, comparable to those of adhesives bonding brackets to enamel, were recorded for four of the systems compared. System l+ and Porcelain Primer had the highest mean values followed by Lee's Enamelite 500, then Vivadent's Silanit, Contact-Resin and Isopast, then 3M's Concise and Scotchprime. Most, if not all, failure sites for the four were at the bracket-resin interface. Two-way factorial analysis of variance demonstrated significant differences at P<.001 among the four adhesives but no contribution of surface effect, whether glazed or deglazed, was suggested statistically. Neuman-Keul sequential range tests showed significant differences between System l+ and the three other systems but no significant differences among the three were detected. Den-Mat's Ultrabond recorded extremely low tensile strength values and was of dubious clinical value. A t-test suggested that deglazing porcelain contributed no significant difference in strength compared with intact, glazed porcelain. All failure sites were at the porcelain-resin interface for this product. Since resin may remain bonded to porcelain following debonding, George Taub's diamond polishing paste and Shofu porcelain polishing wheels were compared as to their ability in restoring the porcelain to its original state. Because of the great adhesive bond of the resin to porcelain, craters, pits or tears may be created when resin is cleaned from porcelain with conventional scalers and pliers. The diamond paste gave a better restorative finish than the stones but the end result depended on the extent of original damage following cleaning. Orthodontists should take this point into account when considering bonding to porcelain crowns or veneers for esthetics sake where final risks may outweigh initial benefits. In a limited survey of 100 orthodontists responding to a questionnaire, 89% indicated that they have bonded or contemplated bonding to composite restored teeth, and 83% indicated that they have bonded or contemplated bonding to porcelain.

Indiana University-Purdue University Indianapolis (IUPUI) / If orthodontic direct bonding adhesives are to be successful, they must withstand the destructive influences of the oral environment and form a durable bond with enamel. Investigators have noted that moisture may be the greatest deterrent to an adhesive bond and water may have the ability to penetrate the adhesive-enamel interface, destroying this bond. An in vitro investigation was undertaken to determine whether moisture and other oral debris can penetrate this adhesive-enamel interface. Four commercially available orthodontic direct bonding systems were tested for microleakage using radioisotope45 calcium chloride (45Ca). Adhesives tested included Orthomite IIS, Directon, Unitek, and Genie. Polycarbonate brackets were bonded to freshly extracted human premolar teeth using the respective adhesive systems. Specimens were stored in 37.5°c water baths for periods of thirty days and ninety days before being tested. All specimens were thermal cycled 2500 cycles to provide a more heroic test. The thermal stressing was carried out at 15°c and 45°c with a 30 second dwell at each temperature. A total of eighty specimens were evaluated. The results of this study suggest that two of the orthodontic adhesives evaluated are susceptible to amounts of microleakage. Storage in water did affect the rate of leakage among the specimens. Generally, more specimens in the groups tested at ninety days showed leakage than at the thirty-day testing period. This study suggests that orthodontic adhesives may be susceptible to microleakage and that this may present problems clinically. However, long-term, well controlled investigations must be undertaken before more definite conclusions can be drawn concerning the effect on bond strength and enamel integrity.

Indiana University-Purdue University Indianapolis (IUPUI) / It is believed that a single force, regardless of its magnitude, tips a tooth around the same center of rotation. This is a histologic investigation of this concept; and an attempt to correlate clinical findings with early and late microscopic changes in the periodontium after light and heavy force application. Five Rhesus monkeys, 3-4 years of age, were used. In one, continuous forces of 40 and 600 gm. were to move a maxillary first bicuspid distally through an edentulous space, with the first molar serving as anchor for 47 days. Both teeth tipped equally toward each other. In four monkeys, light, continuous forces, 10 and 57 gm., and heavy forces, 100 and 200 gm., were used to move the two central incisors lingually over periods of 19, 62, and 66 days. The light force had to be maintained for a period of 4-6 weeks before changing the activation. The 10 gm. force did not move incisors after 19 or 62 days. The 57 gm. force moved the tooth faster than the heavy forces. Hyalinization of the periodontal membrane was recorded during the lag period, but not later. At later stages, the heavy force caused more root resorption than the lighter one. The moment/force ratio determines the center of rotation, not the single value of each. Single forces tipped teeth at the same center of rotation, regardless of their magnitude.

Indiana University-Purdue University Indianapolis (IUPUI) / A manpower survey was conducted by the Great Lakes Society of Orthodontists in early 1977. Permission was obtained from the Society to use a portion of the survey for this thesis, namely: Years since graduation of the respondents, community size in which the respondents practiced, busyness of their practices, number of new patient starts in 1976, change in patient load, and the respondents' opinion of the need for more orthodontists. Statistically, the data was compiled as to percent response by state and as a Region. Mean and standard deviation were obtained and the above factors were then correlated yielding the following findings: The number of orthodontists has increased for the Great Lakes Region, but this increase is showing a leveling off. Except for the province of Ontario and the State of Indiana, the community size in which orthodontists practice is dispersed and not located in large communities. Most orthodontists are starting 90 or more patients per year. Most orthodontists report an increase in their practices, but feel they are seeing fewer patients than they could accommodate comfortably and are less busy than they would like. Few orthodontists in the United States section of the Great Lakes Region feel increases in the numbers of orthodontists are warranted.

Indiana University-Purdue University Indianapolis (IUPUI) / Tooth mobility as it relates to orthodontics has not been thoroughly explored. The immediate aim of this project was to develop and test instrumentation to measure both tooth mobility and instantaneous centers of rotation under forces applied perpendicular to the tooth long axis. Two identical dial micrometers were selected and modified to allow variability in range, calibration, and contact pressure. All forces were delivered by mechanical force meters. A holding device was constructed to permit rigid positioning of a micrometer perpendicular to the long axis of any tooth in the arch and measure mobility at one point on the tooth. With an applied force of 500 gm., mobility measurements were made with the instrument on 44 teeth of six orthodontic patients. By repeating the analyses the instrument reproducibility was demonstrated. The pattern of tooth movement to applied force was explored and related to possible stress levels in tipping movements. A second holding device allowed both micrometers to contact a dental extension which was fixed to a maxillary central incisor. An incisor from each of four preorthodontic and two postorthodontic patients was analyzed. Over 200 clinical centers of rotation were calculated from measurements of tooth movements at two points on the tooth's long axis. Results from the first three patients were erratic. The rotation centers of the last three patients generally remained at midroot and also near the theoretical center of the tooth for all forces applied over 50 gm. More comprehensive studies on tooth mobility are recommended.

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.

Indiana University-Purdue University Indianapolis (IUPUI) / This study was initiated in order to obtain quantitative information on the possible correlations of incisive biting strength and representative cephalometric measurements as taken from the lateral cephalometric headfilm. It consisted of an examination of 150 subjects and a determination of their incisive biting strength. The results of the study indicate that the five cephalometric measurements chosen were of little predictive value in determining incisal biting force.

Indiana University-Purdue University Indianapolis (IUPUI) / It has been debated as to whether teeth may actually be intruded in their alveoli. This study was designed to measure the intrusive movement and histologic response of specific teeth to a known intrusive force. Four Macaque speciosa monkeys were used. The animals corresponded in age to a 12-14 year old human being. Intrusive forces of either 10, 50, 100, or 300 grams were placed on the maxillary first premolars; each force value was held constant during the duration of the experiment, which was 60 days. Maxillary first molars were used as anchorage. Cephalometric headplates proved that all force values were capable of giving intrusion. The 50 gram forces, however, gave the most efficient intrusion. Histologic sections were made on all experimental teeth. 300 and 100 gram forces gave excessive root resorption but the 50 and 10 gram force values elicited only slight root resorption. Root resorption seemed to be directly related to excessive force. The amount of intrusion was not related to a loss of root structure. Bone resorption appeared to allow the intrusion of teeth with minimal tissue damage if proper force values were used.

Indiana University-Purdue University Indianapolis (IUPUI) / Indices to assess malocclusion have been developed for either rating the 'severity of malocclusion' or for prioritizing a patient's need for orthodontic treatment. Most of these indices evaluate the malocclusion through examination of one or two of the following diagnostic records: dental casts, photographs, or clinical exam. However, no prior research had attempted to incorporate all of the above pretreatment orthodontic diagnostic records routinely taken for treatment evaluation. Pretreatment records (dental casts, intra-oral photographs, extra-oral photographs, panoramic radiograph, and a cephalogram, of sufficient quality to be reliably assessed) of 50 completed subjects treated at IUSD Graduate Orthodontic Clinic were evaluated. Subject criteria were a complete set of pretreatment orthodontic records, white non-Hispanic descent in the permanent dentition, absence of any craniofacial anomalies and known pathology. The 3M Unitek TM cephalometric protractor and electronic digital calipers accurate to the nearest tenth of a millimeter were used for measurements. Thirty-six measurements (11 cephalometric, 4 panoramic, 13 dental cast, and 8 photographic) were scored and combined into a total score that represents the new index. The peer assessment rating index (PAR Index) and a subjective ranking of 3 experienced orthodontists (each having more than 20 years of clinical orthodontic experience) were completed on all subjects for determining validity of the new index. All scoring methods were repeated on a subset of 10 random subjects to determine reliability. Statistical analysis showed significant correlations for the ability of the new index to detect severity of malocclusion. Also, the study showed a higher correlation for the new index in representing the experts' rankings than did the PAR index. It is the conclusion of this investigation that the new index is a valid index of malocclusion that more closely reflects experienced orthodontists rankings than the PAR index.

Indiana University-Purdue University Indianapolis (IUPUI) / The main purpose of this investigation was to produce bodily tooth movement. A force system based on the moment to force ratio (m/p ratio) was developed and applied to the teeth by means of springs similar to those used in segmented arch technique. An histologic investigation followed the experimentation. The sample consisted of five adult dogs and a relatively young one, all males. On these dogs, light forces of 165 and 147 gms were used for a period of 17, 30 and 35 days. and heavy forces of 490, 450 and 455 gms were used for a period of 120, 107 and 106 days. An intraperitoneal injection of a vital dye, procion red H8BS, was made before placing the appliance in the mouth and used as a marker between old and new bone. Bodily tooth movement was assessed by measuring new bone apposition on the tension side. Most of the teeth did show pure bodily movement, however, slight tipping was noticed in some instances. Direct bone resorption was recorded in all the teeth moved with light and heavy forces with the exception of very few small areas of hyalinization. The only difference between light and heavy forces was in the severity of root resorption. It was found that the heavier the force, the greater was the anchorage loss. The rate of tooth movement was continuous but not constant.