• CBCT ASSESSMENT OF DENTAL AND SKELETAL ARCH CHANGES USING THE DAMON VS. CONVENTIONAL (MBT) SYSTEM

      Askari, Marjan; Williams, Robert E., D.M.D., M.A.; Barron, Thomas (2012)
      Introduction: This is a pilot study utilizing CBCT to compare cases treated with either the Damon System or conventional mechanics. The primary purpose of this study was to evaluate changes in dental and skeletal arch width and length. The secondary purpose was to evaluate differences between the three CBCT views (3D coordinate, sectional, and volume views). Methods: Eleven Patients (18 years of age or older) with moderate to severe crowding who had both pre- and post-treatment CBCTs and were treated with non-extraction, either with conventional edgewise appliances or with a self-ligating Damon system were retrospectively selected from two orthodontic practices. The arch length, inter-occlusal, inter-apical, inter-buccal and inter-lingual alveolar crest arch widths, and the bucco-lingual angulation for canine, premolars and first molars were measured. Different CBCT views were evaluated by first measuring the interocclusal distances of the respective teeth in the coronal section and the volume views. These measurements were compared with those gathered previously using the 3D coordinate system. A paired t-test, an independent t-test, and an ANOVA were used for statistical analysis. Results: Both non-extraction treatment modalities resulted in interocclusal arch width expansion in both the maxilla and the mandible. The overall expansion of arches in the Damon treated cases, was statistically greater than in the conventionally treated cases. Maxillary and mandibular arch lengths were increased but not significantly in both groups. There were no statistically significant differences between the three different CBCT views. Conclusion: Both the Damon and conventional systems resulted in increased arch width and length, but the Damon system caused significantly more overall arch expansion. There was less tipping of the teeth during arch expansion in the conventional system. The ratio of crown to root movement in the conventional system versus Damon group in the maxilla was approximately 1:1 versus 3:1 and in the mandible 3.6:1 versus 6:1. Using the 3D coordinate systems to evaluate the interocclusal points in CBCT yields the most exact measurements but the volume and sectional views provide accurate measurements of arch length and arch width.
    • Coated Rectangular Composite Archwires: A Comparison of Self-Ligating and Conventional Bracket Systems During Sliding Mechanics

      Woods, David K.; Williams, Robert E., D.M.D., M.A. (2013)
      The purpose of this study was to analyze the resistance to sliding of coated rectangular fiber reinforced composite archwires using various brackets systems and second-order bracket angulations. Resistance to sliding was investigated for eight bracket systems: six self-ligating brackets (four passive and two passive-active) and two conventional brackets. A rectangular fiber reinforced composite archwire of 0.019 x 0.025-in dimension from Biomers® SimpliClear was drawn through a three-bracket model system at ten millimeters per minute for 2.5 millimeters. For each bracket, the resistance to sliding was measured at four bracket angulations (0, 2.5, 5, and 10 degrees) in a dry state at room temperature. The fiber reinforced composite archwire produced the lowest sliding resistance with the passive self-ligating bracket system (Damon DQ) at each bracket angulation tested. Overall, self-ligating bracket systems generated lower sliding resistance than conventionally ligated systems, and one passive/active self-ligating bracket system (In-Ovation-R). There was a significant increase in resistance to sliding as bracket angulation increased for all bracket systems tested. Microscopic analysis revealed increased perforation of the archwire coating material as bracket angulations were increased. Our findings show that the rectangular fiber reinforced composite archwire may be acceptable for sliding mechanics during the intermediate stages of orthodontic tooth movement, however more long-term studies are needed.
    • The Effect of Annealing on the Elastic Modulus of Orthodontic Wires

      Higginbottom, Kyle; Williams, Robert E., D.M.D., M.A. (2014)
      Introduction: Nickel Titanium orthodontic wires are currently used in orthodontic treatment due to their heat activated properties and their delivery of constant force. The objective of this study was to determine the effect of annealing on the elastic modulus of Nickel Titanium, Stainless Steel and Beta-titanium (TMA) wires. Different points along the wire were tested in order to determine how far from the annealed ends the elastic modulus of the wires was affected. Methods: Eighty (80) orthodontic wires consisting of 4 equal groups (SS/TMA/Classic Nitinol®/Super Elastic Nitinol®) were used as the specimens for this study. All wires were measured and marked at 5mm measurements, and cut into 33.00mm sections. The wires were heated with a butane torch until the first 13.00mm of the wires were red hot. Load deflection tests using an Instron® universal testing machine were run at 5mm distances from the end of the wire that had been annealed. The change in elastic modulus was then determined. Results: There was a significant difference (F = 533.001, p = 0.0005) in the change in elastic modulus for the four distances. There was also a significant difference (F = 57.571, p = 0.0005) in the change in elastic modulus for the four wire types. There was a significant interaction (F = 19.601, p = 0.005) between wire type and distance, however this interaction negated the differences between the wires. Conclusion: 1) There are significant differences in the changes in elastic modulus between the areas of the wires within the annealed section and those areas 5mm and 10mm away from the annealed section. The change in elastic modulus within the annealed section was significantly greater at 8 mm than it was at 13mm, and this was significantly greater than 18mm and 23mm (5mm and 10mm beyond the annealed section). However, there was no statistical difference in the change in elastic modulus between 5mm and 10mm away from the annealed section (18mm and 23mm respectively). 2) Regardless of the wire type, no clinically important effects were seen 5mm and 10mm beyond the annealed portion.
    • The Effect of Bracket Manipulation at Various Time Intervals on Final Bond Strength of Three Orthodontic Adhesives

      Stern, Moshe; Williams, Robert E., D.M.D., M.A. (2013)
      Introduction: Adhesive bond strength is an essential component for the success of orthodontic treatment and it is important to understand what factors can affect its clinical effectiveness. The primary purpose of this study was to attempt to establish clear parameters for the effect that manipulation at various time intervals will have on the final bond strength of orthodontic adhesives. The secondary goal was to evaluate the characteristics of three adhesives (Transbond Plus, Grengloo, and Light-Bond) and test the effect that bracket manipulation at various time intervals will have on their final bond strength. Methods: Sixty (60) extracted human premolar teeth with intact buccal surfaces were collected and stored in a plastic tube containing distilled water. Prior to data collection, all teeth were mounted in acrylic filled plastic tubing. Each tooth was marked with black permanent marker 10 degrees from the midpoint/cusp tip using a 10 degree angular wedge. This mark established the amount each bracket would be turned after the allotted time interval had passed. The buccal surface of each tooth was cleaned with pumice, and etched for 30seconds. Each tooth was lightly coated with Assure Universal Bonding Resin® primer and a Victory Series®, MBT prescription; premolar bracket was bonded using one of the adhesives being tested. The brackets were then manipulated at various time intervals (30sec, 2min, 3min, and 4min) and then cured. After 24 hours in a controlled environment the shear bond strengths of the adhesives were tested using an Instron® universal testing machine. Results: There was a statistically significant difference between the shear bond strengths of Grengloo, Lightbond, and Transbond, with Transbond having stronger bond strength than either of the other adhesives. There was no statistically significant difference in shear bond strength between Grengloo and Light Bond. An observed power of 0.872 was found for this data. There was a difference approaching significance (F=2.45, p=0.071), between the different times elapsed prior to bracket manipulation and curing. In general the bond strength decreased as more time elapsed prior to bracket manipulation and curing. There was no significant interaction (F=0.55, p=0.771), between the types of adhesive and the times prior to curing. Conclusion: 1) There is no statistically significant decrease in bond strength of the adhesives tested as time elapsed (30 seconds, 2 minutes, 3 minutes, 4 minutes) prior to bracket manipulation. 2) All time intervals had clinically acceptable bond strength. The difference in bond strength between 30 seconds and 4 minutes was approaching significance. If a larger sample size is tested, 4 minutes might be found as the threshold for significant decrease in bond strength. 3) Transbond Plus had statistically significant higher bond strength (32% and 35% greater) than Light Bond and Grengloo. The difference in bond strength between Light Bond and Grengloo was not statistically significant.
    • The Effect on Final Bond Strength of Bracket Manipulation Subsequent to Initial Positioning

      Beebe, David; Williams, Robert E., D.M.D., M.A. (2011)
      The shear bond strength of light activated orthodontic adhesives varies according to the composition of the material, placement protocol, and time prior to light curing. Manipulating brackets after their initial placement on a tooth can disrupt the adhesive's polymerization and compromise final bond strength. No previous research has investigated how a specific degree of manipulation, and the amount of time elapsed prior to curing, under specific lighting conditions, affects the orthodontic adhesives shear bond strength. Victory Series®, MBT prescription, premolar (3M Unitek, Monrovia, CA) orthodontic brackets were bonded using three different adhesives to sixty (60) bicuspids and varying the time after bracket manipulation before curing. The shear bond strength was calculated for each specimen. The brackets were debonded and the same teeth were rebonded with new, identical brackets, using the same protocol and under the same conditions. The results showed a statistically significant difference between the shear bond strength of Transbond XT and Grengloo, with Transbond XT having the highest strength. There was also a statistically significance difference in bond strength between the group cured 30 seconds after manipulation and the groups manipulated at different intervals prior to curing, with the 30 second group having the highest bond strength. This study confirms that various orthodontic adhesives have different bond strengths depending on manipulation and varying times prior to curing each adhesive.
    • An In-Depth Analysis of Borderline Class I Malocclusions in Black Patients at the University of Maryland

      Johnson, Evan M.; Williams, Robert E., D.M.D., M.A. (2013)
      Problem: To determine if a group of UMB Orthodontic faculty determines there to be equal numbers of extraction and nonextraction cases in treatment planning borderline Class I malocclusions in black patients, and second, to determine the variables that are most important in the diagnosis and evidence-based treatment planning of these cases. Methods: All black patients treated in the UMB Orthodontic Graduate Clinic having completed initial orthodontic records over a three-year period were evaluated for the presence of a Borderline Class I Malocclusion. Of the initial 171, 15 subjects were statistically determined to be Borderline and were subsequently subjected to analysis by 14 orthodontic faculty members. Based on faculty analysis, 11 of the cases were categorized as extraction or non-extraction and were evaluated for those variables determined to be indicative of Borderline Class I malocclusions in black patients based on logistic regression. Results: Significantly more (X2=4.876, p = 0.027) extraction cases were reported (57.6%) than non-extraction cases (42.4%). 66.9% of the extraction plans involved only first bicuspids. The regression analysis showed that a 100% predictability of the evidence-based treatment plan was obtained by evaluating overbite, interarch midline discrepancy, WITS, lower crowding, overjet, IMPA, U1-SN, L1-NB and upper crowding. Overbite (p = 0.017) and interarch midline discrepancy (p = 0.019) were statistically significant in treatment planning. WITS approached significance (p = 0.096). Conclusions: Due to the limited study sample, one can make several inferences in regards to Borderline Class I malocclusions in black patients that must be interpreted with caution. The orthodontic faculty members extracted 57% of the time. The most common extraction pattern is four first bicuspids (~2/3 of the time). Dental overbite proved to be the most statistically significant variable when treatment planning. Interarch midline discrepancies proved to be the second most statistically significant variable when treatment planning. The WITS variable approached statistical significance. Lower crowding, overjet, IMPA, U1-SN, L1-NB and upper crowding were found to be non-significant in making the evidence-based treatment planning decision although a treatment plan with 100% predictability can be obtained by analyzing all nine variables.
    • An In-Depth Analysis of Borderline Class I Malocclusions in Caucasian Patients at the University of Maryland

      Groy, Sarah Pavon; Williams, Robert E., D.M.D., M.A. (2014)
      Problem: To determine if a group of experienced clinicians determines there to be equal numbers of extraction and nonextraction treatments planned when evaluating borderline Class I malocclusions in Caucasian patients, and second, to determine the variables that are most important in the diagnosis and evidence-based treatment planning of these cases. Methods: All Caucasian patients treated in the University of Maryland, Baltimore Orthodontic Graduate Clinic having completed initial orthodontic records over a three-year period were evaluated for the presence of a borderline Class I Malocclusion. Of the initial 180 subjects, 15 were statistically determined to be borderline and were subsequently subjected to analysis by 11 orthodontic faculty members. The cases were then evaluated for those variables determined to be indicative of borderline Class I malocclusions in Caucasian patients based on stepwise forward logistic regression. Results: There was no significant difference between the treatment plan recommended and the 50/50 treatment expected for borderline cases (X2=0.055, p = 0.8153), although extraction treatment was slightly more likely to be chosen by those surveyed (50.9%) than non-extraction treatment (49.1%). As determined through logistic regression, the four most significant variables were the mandibular intercanine measurement and maxillary crowding, (both study model variables), followed by the cephalometric Z-angle and the upper lip to E-plane measurement. Conclusions: The results of the first stage of this study, which evaluated the percentage of extraction and non-extraction cases planned by faculty members when evaluating borderline Class I malocclusions in Caucasian patients, found that there was no significant difference in the percentage of extraction and non- extraction treatments planned The most common extraction pattern was the extraction of all four first bicuspids (44.1%). The results of the second stage of the study identified cephalometric and study model variables that were indicators of borderline Class I malocclusions in Caucasian patients. The four variables with the highest B value significance levels were identified through logistic regression to be the mandibular intercanine width and maxillary arch crowding, followed by the Z-angle and the upper lip to E-plane measurement.
    • The influence of various demographic and social factors on patient perceptions regarding orthodontic treatment

      Widmer, Lauren Errington; Williams, Robert E., D.M.D., M.A. (2013)
      While orthodontic patients previously received information about their treatment primarily through their orthodontist, there may now be a shift in the way in which patients obtain information, as well as in the information that they receive. This study sought to determine how much patients knew about manufacturer's claims of alternative orthodontic treatments and their level of positivity towards those treatments. The manufacturer's claims studied were those made by Align Technologies (Invisalign®), Ormco (Damon®), and DenMat Holdings (Six Month Smiles® and Snap-On Smile®). The demographic variables studied were gender, age, ethnicity, and place of care. To sdetermine these differences in perception, a survey was designed and distributed to patients, age 14-50, who presented for an initial appointment at either the University of Maryland Dental School Orthodontic Clinic or at private practices in the Baltimore/Washington, D.C. area. One hundred and thirty-one surveys were completed over a four month period. Differences in demographic variables between those patients seeking care at the Dental School versus private practice were analyzed using chi-square and Fisher's exact tests. ANOVA and Kruskal-Wallis ANOVA were used to compare (a) knowledge of manufacturer's claims in general, (b) knowledge of Invisalign's® claims specifically, and (c) the desirability of Invisalign® for patients with the following variables: gender, age, ethnicity, and place of care (either the Dental School or private practices). Differences were found between patients seeking care at the Dental School versus patients seeking care in private practice for the following variables: ethnicity; chief complaint; and the number of magazines read. We also found that patients age 14-18 had less knowledge of Invisalign's® claims and thought Invisalign® was less desirable than patients age 19-30 or 31-50.
    • The Effect of Malocclusion Severity and Treatment Duration on Patient Satisfaction with Clear Aligner Therapy

      Wiese, Lauren Elizabeth; Bosio, Jose A.; Williams, Robert E., D.M.D., M.A.; 0000-0003-0335-7606 (2019)
      Objective: Determine if a patient’s initial malocclusion and treatment duration influenced satisfaction with clear aligner (Invisalign®) therapy. Methods: Thirty-three orthodontic patients treated with clear aligners responded to a satisfaction questionnaire containing twenty-one questions relating to their satisfaction with treatment, approximately two years after completing treatment. Overjet, overbite, and maxillary and mandibular anterior crowding/spacing were measured to determine the initial severity of their malocclusion. Logistic regression analyses with satisfaction factors as the dependent variable were used to quantify associations between patient satisfaction regarding both the initial severity of malocclusion and treatment duration. Results: Overall, patients were satisfied with aligner treatment. However, no significant associations were observed between patient satisfaction and either the initial severity of the malocclusion or treatment duration. Conclusion: The current study does not find that initial malocclusion or treatment duration significantly affects patient satisfaction. Patient satisfaction with clear aligner therapy is generally very high, and multi-factorial.