The purpose of this prospective clinical study was to investigate differences in outcomes from two common treatment modalities used to reduce deep overbite: maxillary incisor intrusion using an intrusion arch and posterior tooth eruption using an anterior bite plate and to assess their influence on smile esthetics. Pre-treatment and post-overbite correction records were gathered from 40 patients with deep overbite malocclusions at the Virginia Commonwealth University orthodontic clinic. Intrusion arch patients displayed significant reductions in maxillary incisor display accompanying documented incisor intrusion. Bite plate patients showed significant lower incisor intrusion and increases in the mandibular plane angle. When compared to the bite plate group, there was a greater tendency for flattening of the smile arc seen in the intrusion arch group. Changes in the smile arc were likely partially a result of the mechanics used but may also have been due to other factors involved in orthodontic tooth alignment.

The purpose of this study was to help predict the enamel thickness of mandibular incisors. At least two direct digital periapical radiographs were made for each of the 80 subjects. Radiographs were scaled to control for magnification errors using dental study models and computer software. Mesiodistal incisor width and mesial and distal enamel thicknesses were measured. Lateral incisors were determined to be wider than central incisors and distal enamel thicknesses were larger than mesial enamel thicknesses on average. The African American group demonstrated wider incisors and enamel thicknesses than the Caucasian group on average. Enamel thickness positively correlated with tooth width for all incisors. No statistically significant differences were detected between male and female groups. Some conclusions relating to enamel thickness can be made based on race, incisor position, and incisor width, but correlations were not considered strong enough to accurately determine enamel width, without the aid of radiographs.

The purpose of this study was to determine the influence of sagittal mandibular position on preferred lip position in profile. Five androgynous silhouette profiles differing only in the degree of mandibular retro- or prognathism (-25º, -18º, -11º, -4º, & +3º facial contour angles) were created. Using a computer animation program, evaluators moved the lips independently into the position deemed to be the most esthetic for each profile. Evaluators included adolescent orthodontic patients, parents of patients, and orthodontists. In general, no differences in preferred lip position were found between the –11º & -4º profiles or between the –18º & +3º profiles, but preferences for each of the three profile groupings (-11º & -4º, -18º & +3º, and –25º) were different. No differences were found among the three evaluator groups or between male and female evaluators. Scattered and inconsistent differences were found among lip preferences for male and female profiles.

The purpose of this study was to determine if dental esthetics affects the perception of adolescents regarding their peer's social aptitude in specific areas such as athletics, popularity, leadership, and academics. Ten patient photographs (4 males, 6 females) from a private orthodontic practice in Richmond, VA were selected for inclusion in this study. The frontal smiling photographs were digitally modified with insertion of either an ideal smile (straight) or a non-ideal smile (crooked) to create an image identical to the original except for an altered dental complex. Laypersons rated the straight and crooked patient photographs for athletic performance, socialization skills (popularity), leadership, and academic performance using a 100 mm visual analog scale (VAS). Picture ratings were analyzed using a repeated-measures mixed-model analysis (SAS version 9.1, SAS Institute, Cary NC). On average, the differences due to crooked vs. straight were consistent in that patients with straight teeth were always rated more highly than the same patients with crooked teeth. These differences were significant in ratings of perceived athletic performance (P .05).

In vitro bond strength studies are of great importance and interest since they allow the prediction of clinical success of orthodontic adhesives. There are many studies that have investigated bond strength values of bonding systems. However, due to the variation in the materials and methods employed, it is very difficult and often impossible to make comparisons among data. The use of a substrate as an alternate to enamel for mechanical tests would minimize these variables and reduce the challenges faced with in vitro bond strength tests. The purpose of this study was to investigate the suitability of Macor as a substrate for bond strength testing of orthodontic adhesives. Macor samples were custom prepared in a shape similar to that of a human maxillary premolar. The groups tested were: Group 1: acid-etched with 9.6% hydrofluoric acid (HFA) for 60 seconds; Group 2: acid-etched with 9.6% HFA for 90 seconds; Group 3: acid-etched with 9.6% HFA for 120 seconds; Group 4: surface roughened with silicon carbide (Sic); and control group: human premolars etched with 37% phosphoric acid. Following surface preparation, samples were primed and brackets were bonded using Transbond XT (3MlUnitek). Mounted samples were stored in water for 24 hours at 37OC until mechanical testing. Brackets were debonded in the shear mode using an Instron Universal Testing Machine and the force at debond was recorded. The nature of adhesive bond failure among the groups was also compared using an adhesive remnant index (ARI). One-way ANOVA and Weibull analysis statistical tests were used to evaluate and compare the groups. Sample surfaces were analyzed under the light microscope to determine the mode of bond failure for ARI. The Kruskall-Wallis test was used to determine differences in the ARI scores. There were statistically significant differences in shear bond strengths among the enamel and Macor groups (p 0.05). The shear bond strength values of the Macor groups were significantly lower than those of the enamel control group, (p < 0.05). ARI scores were significantly different between the groups (p 10.0001); Macor samples treated with hydrofluoric acid had more adhesive remaining on their surfaces than those in the control and Sic groups. Based on the results of this study, Macor may not be a suitable substrate for bond strength testing in orthodontics.

Recently, soft tissue lasers have been introduced into orthodontic practice to perform procedures that were traditionally referred to other dental professionals. The purpose of this study was to compare the attitudes of orthodontists, periodontists, and general dentists regarding the use of soft tissue lasers by orthodontists. The ultimate goal was to facilitate communication among dental professionals and improve the care of orthodontic patients requiring management of soft tissues. A survey was developed to evaluate and compare the current opinions of orthodontists (n=330), periodontists (n=171), and general dentists (n=77) regarding orthodontists’ use of soft tissue lasers. When compared to orthodontists and general dentists, a lower percentage of periodontists indicated that soft tissue laser use by orthodontists was appropriate (P = 0.001). Also, for each of the 8 specific soft tissue laser procedures investigated, periodontists reported a significantly lower level (P = 0.001) of appropriateness than did orthodontists and general dentists.

Purpose: This in vitro study evaluated the effectiveness of using a 37% phosphoric acid liquid etchant along with MI Paste Plus™ powered technology compared to using MI Paste Plus™ alone or to an artificially created saliva solution in decreasing the demineralization and enhancing the remineralization of artificial carious lesions created on extracted human teeth. The teeth were analyzed and compared using polarized light microscopy, quantitative light-induced fluorescence, and digital photography. Materials and Methods: One hundred three recently extracted non-carious human third molar teeth without observable white-spot lesions, decalcification, or dental fluorosis were selected for this twelve day study and randomly divided into four treatment groups as follows: Group 1 (Control) - Artificial saliva solution (27 teeth) Group 2 (MIP) - MI Paste Plus™ application for 30 minutes daily for 12 days (26 teeth) Group 3 (15MIP) - 15 second etch every third day and MI Paste Plus™ application for 30 minutes daily for 12 days (25 teeth) Group 4 (1MIP) - 1 minute etch on day one ONLY and application of MI Paste Plus™ for 30 minutes daily for 12 days (25 teeth). Results: Results of one<–>way ANOVA revealed there was a significant effect for the type of treatment on the lesion depth (p = 0.0027). The post-hoc Tukey-Kramer's test indicated there was a statistically significant difference between the two groups (15MIP and 1MIP) that incorporated an acid etch in combination with MI Paste Plus™ and the group with exposure to MI Paste Plus™ alone (MIP). In addition, results of one<–>way ANOVA showed that there was no statistically significant effect for type of treatment on the change in fluorescence (p = 0.1417) or the change in density (p = 0.1934). Conclusions: The results of the present study revealed there was a significant effect for the type of treatment on the lesion depth (p = 0.0027). However, the only significant difference found was between the two groups (15MIP and 1MIP) that incorporated an acid etch in combination with MI Paste Plus™ and the group with exposure to MI Paste Plus™ alone (MIP). Thus, daily applications of MI Paste Plus™, with or without an acid etch, did not produce a statistically significant difference in mean lesion depth when compared to the control (artificial saliva group). In addition, the results of the present study showed that there was no statistically significant effect for type of treatment on the change in fluorescence (p = 0.1417) or the change in density (p = 0.1934). Further research is needed to evaluate MI Paste Plus™ capability in prevention of demineralization and/or enhancement of remineralization by conducting randomized clinical trials.

The purpose of this work is to study phenotypic craniofacial traits of unaffected parents of individuals with nonsyndromic cleft lip with or without palate (NSCL/P). In order to evaluate these craniofacial traits, three dimensional photographs were obtained and landmarked to compare the sample of unaffected parents with a control sample. The sample was comprised of 40 unaffected fathers, 25 control males, 84 unaffected mothers, and 34 control females. Twenty-four three-dimensional landmarks were exported for analysis for each subject. For the purposes of this study, nine euclidean distances were subjected to a discriminant function analysis to evaluate their ability to discriminate between an unaffected parent and a control. In both the male and female analysis, certain craniofacial measurements correctly and significantly discriminated between unaffected parents and controls. It appears that certain facial traits are subclinical markers for enhanced genetic susceptibility to nonsyndromic cleft lip with or without palate.

Background: Nonsyndromic cleft lip and palate (NSCL/P) is a complex trait caused by genetic and environmental factors that interact producing a wide spectrum of orofacial malformations, including dental anomalies. The underlying genetic etiology that accounts for phenotypic variation in affected families is poorly understood. Purpose: The purpose of this study is to utilize shape and microesthetic analysis to characterize the maxillary anterior dentition in unaffected parents of children with NSCL/P (cases) compared to control adults with no CL/P history to identify dental morphology features that are part of the NSCL/P phenotypic spectrum and can therefore be used in refining NSCL/P phenotypes and identifying genetic risk factors. Methods: Individuals were recruited from 5 sites including Iowa, Texas, Hungary, the Philippines, and Pittsburg, PA. From a total of 3202 individuals, 420 quailified after strict selective criteria. Digital photographs from 198 cases and 222 controls were analyzed using linear metrics and 2D-coordinate landmark-based geometric morphometrics (GM) to compare dental esthetics and deviations from golden proportions." Differences in central incisor and connector height proportions were evaluated using paired T-tests. Anterior tooth shapes were examined using GM techniques. Results: Three shape differences were found to be possible predictors of genetic risk. These included shorter maxillary anterior teeth overall, square shaped lateral incisors on the left side, as well as lateral incisors and canines with long axes angled inward toward the midline on the left side. Both the case and control groups were found to be significantly different than the proposed ideal values of tooth proportions. Conclusions: Significant differences in anterior dental morphology were found between cases and controls, with controls displaying a more ideal dental morphology than cases for most evaluated measures. The identification of these distinct dental features in carriers of NSCL/P genetic risk factors further characterizes the phenotypic spectrum of NSCL/P which can enhance the power of genetic studies.

ABSTRACT EVALUATION OF FIT FOR 3D PRINTED RETAINERS AS COMPARED TO THERMOFORM RETAINERS By David Cole, D.M.D. A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Dentistry at Virginia Commonwealth University Thesis Directors: Eser Tüfekçi, D.D.S., M.S., Ph.D., M.S.H.A. Professor, Department of Orthodontics Sompop Bencharit, D.D.S., M.S., Ph.D. Associate Professor and Director of Digital Dentistry, Department of General Practice Introduction: Despite recent advances in three-dimensional (3D) printing, little information is available on 3D printed retainers Methods: Three reference models were used to fabricate traditional vacuum formed, commercially-available vacuum formed, and 3D printed retainers. For each model, three retainers were made using the three methods (a total of 27 retainers). To determine the trueness, the distances between the intaglio surface of the retainers and the occlusal surface of the reference models were measured using an engineering software. A small difference was indicative of a good fit. Results: Average differences of the traditional vacuum formed retainers ranged from 0.10 to 0.20mm. The commercially-available and 3D printed retainers had a range of 0.10 to 0.30mm and 0.10 to 0.40mm, respectively. Conclusions: The traditional vacuum formed retainers showed the least amount of deviation from the original reference models while the 3D printed retainers showed the greatest deviation.