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Biomedical subjects

Carla A Evans

Publications and source records attributed to Carla A Evans.

At least 19 recordsLinked to original sources
PubMed2007

Assessing the American Board of Orthodontics objective grading system: digital vs plaster dental casts.

INTRODUCTION: The purposes of this study were to determine whether the American Board of Orthodontics objective grading system (ABO OGS) can be assessed accurately from digital dental casts and whether there are statistical differences between digital and plaster dental casts in scoring the ABO OGS. METHODS: Thirty posttreatment plaster dental casts were selected and scanned by OrthoCAD (Cadent, Carlstadt, NJ) to produce 30 corresponding digital dental casts. The plaster and digital casts were compared by using the criteria of the ABO OGS. Because the data were ordinal, a nonparametic statistical analysis was used. RESULTS: The Wilcoxon test for paired samples showed significant differences between the plaster and digital casts for occlusal contacts, occlusal relationships, and total scores (P <.05). No significant differences were found for alignment, marginal ridges, overjet, and interproximal contacts. Buccolingual inclination was not included in this study because of inability to perform proper measurements with the OrthoCAD program. Mean differences of points deducted ranged from .03 point for marginal ridges to 5.07 points for the total score. The variable with the most points deducted related to occlusal relationships, and the fewest points were deducted for interproximal contacts. CONCLUSIONS: Based on this study, the current OrthoCAD program (version 2.2) was not adequate for scoring all parameters as required by the ABO OGS.

Certification↗
PubMed2006

Facial profile preferences of black women before and after orthodontic treatment.

INTRODUCTION: The purposes of this study were to determine (1) profile preferences of black female patients and (2) whether they can recognize their own profile images before and after orthodontic treatment. METHODS: Fifteen black orthodontists, 15 white orthodontists, and 15 black female patients were asked to indicate the images they considered most pleasing and to determine a zone of acceptability for 3 black female profiles. Raters used the PERCEPTOMETRICS computer program (Health Programs International, Wellesley, Mass). In addition, the 15 patients were asked to identify their most accurate pretreatment and posttreatment profile images. RESULTS: Analyses of variance showed that the white orthodontists preferred flatter profiles than the black women, who in turn preferred fuller profiles than the black orthodontists. Significant differences in lip position were detected for most pleasing and midpoint of acceptability among the 3 groups of judges, with no significant differences in any variables measured between treatments in rating the 3 images. No significant differences were detected for the magnitude of the zone of acceptability. All 15 black women recalled having fuller profiles than they actually did before treatment, but they could correctly identify their own profile images after treatment. CONCLUSIONS: The results of this study will facilitate the understanding of the physical bases of the esthetic judgments of black and white orthodontists and black female patients.

Adult↗
PubMed2006

Bond strength evaluation of ceramic and stainless steel bracket bases subjected to cyclic tensile loading.

INTRODUCTION: The aim of this study was to evaluate the effects of loading, static and cyclic, on 1 stainless steel and 3 ceramic bracket bonding bases. METHODS: The brackets were chosen because of the different characteristics of their bonding bases. The brackets in each group were bonded to bovine teeth by using the same adhesive and subjected to both static and cyclic tensile loading; the results were analyzed (ANOVA and Scheffé) for statistical differences among the groups. RESULTS: The analysis showed that ceramic brackets have unique characteristics compared with stainless steel; the most significant is higher bond strengths. The effects of cyclic loading were shown to be significant, in that fatigue testing caused a decrease in mean tensile bond strength for most groups. An additional factor on the bond strength might be the composition and design of the bracket base. CONCLUSIONS: Simulations of occlusal forces (a combination of tensile, shear, and compressive forces) to orthodontic materials during in-vitro studies in accordance with clinical use might adequately describe actual clinical performance.

Analysis of Variance↗
PubMed2006

Antimicrobial properties of an orthodontic adhesive combined with cetylpyridinium chloride.

INTRODUCTION: Patients undergoing fixed appliance treatment are at greater risk for increases in salivary and plaque levels of Streptococcus mutans and an elevated risk of dental caries. Cetylpyridinium chloride (CPC) is known to be an effective antiplaque agent. The purpose of this study was to investigate whether incorporating CPC into a commercially available orthodontic adhesive would impart antimicrobial properties without altering the diametral tensile strength of the material. METHODS: CPC was added to a commercially available, filled, photo-activated bracket adhesive (Transbond XT, Unitek 3M, Monrovia, Calif) in varying amounts, to obtain specimens with CPC concentrations of 0% (control), 2.5%, 5.0%, and 10.0% by weight. Adhesive discs 2 mm thick and 4 mm in diameter were incubated with Streptococcus mutans for 48 hours. The diameters of the zones of bacterial inhibition were measured in an agar disc diffusion assay; specimens of each concentration were tested every other week for 196 days. Other discs were soaked in distilled water for 180 days. The amount of CPC released into the water from the modified discs was measured and recorded on days 7, 15, 30, 60, and 180 by using a spectrophotometer at 254 nm. Diametral tensile strength of the modified adhesive discs was measured with a universal testing machine, and the effect of water aging was also evaluated. RESULTS: The measured zone of bacterial inhibition increased as CPC content increased. All CPC-adhesive specimens maintained antimicrobial activity up to 196 days. No zone of bacterial inhibition was measured around the control specimens. CPC release was observed through the end of 180-day period, but the greatest release was recorded in the first week. There was no significant difference (P < .05) in diametral tensile strength between the 2.5% CPC-adhesive group and the control; there were significant differences among the 5.0% and 10.0% CPC-adhesive groups and the control. Water aging had no significant effect on diametral tensile strength other than decreasing it for the test group containing 10.0% CPC. CONCLUSIONS: The incorporation of 2.5% CPC in adhesive material imparted antimicrobial activity without altering diametral tensile strength.

Adhesives↗
PubMed2006

Midfacial morphology in adult unoperated complete unilateral cleft lip and palate patients.

OBJECTIVE: To examine lateral cephalometric radiographs of adult unoperated cleft lip and palate patients for the purpose of clarifying whether maxillary deficiencies observed in treated cleft patients result from intrinsic defects or surgical intervention early in life. MATERIALS AND METHODS: This retrospective study examined lateral cephalograms of 30 adult patients with nonsyndromic complete unilateral cleft lip and palate (CUCLP). The lateral cephalograms were traced and evaluated for size and position of the cranial base, maxilla, maxillary dentition, mandible, and mandibular dentition as well as for vertical relationships. Comparisons with 30 adult noncleft individuals were made. RESULTS: In unoperated adult cleft lip and palate patients, the cranial base angle was increased with the anterior cranial base reduced in length. The maxilla was found to be normal in size and somewhat prognathic in position. Both the maxillary and mandibular incisors were relatively upright. The mandible was smaller in size and posteriorly positioned. CONCLUSIONS: The potential for normal growth of the maxilla exists in patients with CUCLP. It is likely that disturbances of maxillary growth in surgically operated cleft patients are related primarily to the surgical intervention.

Adolescent↗
PubMed2006

Profile preferences of Korean American orthodontic patients and orthodontists.

AIM: The purpose of this study was to determine differences in preference for Korean American facial profiles among Korean American orthodontic patients with 2 levels of acculturation, Asian American orthodontists, and Caucasian orthodontists. METHODS: Images of 1 male and 1 female Korean American adult were animated to move parts of the faces from an extreme retrusive position to an extreme protrusive position by using the Perceptometrics computer program. Three movies were created of the nose, lips, and chin for each image. Three groups of judges, ie, 18 Korean American orthodontic patients, 17 Asian orthodontists, and 18 Caucasian orthodontists selected the most pleasing position and the zone of acceptability as a measure of tolerance. RESULTS: Statistically significant differences were found between Caucasian orthodontists and Korean American orthodontic patients for the most pleasing and midpoint of acceptability positions of female nose and male chin, with no differences in the zone of acceptability position among the groups. CONCLUSION: In general, the Korean American orthodontic patients preferred a more protrusive nose on the female image and more retrusive chin on the male image than Caucasian orthodontists for the most pleasing and midpoint of acceptability positions, with similar zone of acceptability for all 3 groups.

Acculturation↗
PubMed2005

Preferences for facial profiles between Mexican Americans and Caucasians.

The objective of this study was to determine differences between Mexican American and Caucasian judges in the acceptability of lip protrusion in computer animations of two male and two female persons of Mexican descent. Thirty Caucasians and 30 Mexican Americans of varying age, sex, education, and level of acculturation responded to facial profile computer animations that moved lips from an extreme protrusive to an extreme retrusive position. Judges were asked to complete two tasks: (1) to press the mouse button when the image was perceived to be most pleasing (MP) and (2) to determine the boundaries of a zone of acceptability (ZA) of lip protrusion by pressing the mouse button when the moving image became acceptable and releasing it when the image of the protrusion became unacceptable. In general, Mexican Americans preferred upper or lower lip positions to be less protrusive than did Caucasians. Larger mean ZAs for both upper and lower lip positions with male computer animation images and lower lip position for female computer animation images were found among Caucasians when compared with low-acculturated Mexican Americans. A significant mean difference in midpoint of acceptability (MA) for lip position between Caucasians and low-acculturated Mexican Americans was observed for both upper and lower lip position with female computer animation images.

Acculturation↗
PubMed2004

Immunohistochemical localization of alphavbeta3 integrin receptor during experimental tooth movement.

During orthodontic treatment, multinucleated clast cells carry out the resorption of mineralized tissues. Adhesion of clast cells to the mineralized tissues is mediated by transmembrane cell-surface glycoproteins called integrins, specifically by the alphavbeta3 integrin, which plays an important role in the process of bone resorption. The role of the alphavbeta3 integrin in bone resorption leading to osteoporosis has been demonstrated, but its role in alveolar bone and root resorption during orthodontic tooth movement is unknown. This study examined the expression of the alphavbeta3 integrin during experimental tooth movement. Tooth movement was achieved in 16 male Sprague-Dawley rats (each weighing 120-200 g) with elastic bands between their maxillary first and second molars. The molar-bearing segments were dissected and processed for histologic and immunohistochemical examination. The expression of alphavbeta3 integrin was examined with 2 primary antibodies: a polyclonal anti-alphav integrin subunit antibody and a polyclonal anti-beta3 integrin subunit antibody. Negative controls were similarly processed but without incubation with primary antibodies. The alphavbeta3 integrin was expressed both by osteoclasts associated with alveolar bone resorption and by odontoclasts associated with root resorption during experimental tooth movement. Furthermore, the beta3 integrin subunit was expressed by the epithelial rests of Malassez in the periodontal ligament. Negative controls did not show immunolabeling. The alphavbeta3 integrin adhesion receptor is expressed during experimental tooth movement and might be involved in the process of mineralized tissue resorption and the functions of the epithelial rests of Malassez.

Alveolar Process↗
PubMed2004

Orthodontic treatment for patients with clefts.

Orthodontic strategies continue to evolve as new methods and treatment concepts more directly address the specific problems of patients who have clefts. By continual review of treatment outcomes and comparing outcomes with patients' problem lists and treatment objectives, clinicians will identify areas of treatment needing improvement and formulate hypotheses for future research.

Adolescent↗
PubMed2004

An exploratory study of orthodontic resident communication by patient race and ethnicity.

Race has been shown to affect the quality of physician-patient relations. In view of this, dentistry must consider whether race also affects dentist-patient relations. The purpose of this study was to explore whether orthodontic residents showed more social connection and concern for European ancestry patients, were more negative to minority patients, and appropriately used interventions designed to overcome cultural differences. Communications in sixty-eight dentist-patient encounters were analyzed using the Roter Interaction Analysis System (RIAS). The frequencies of each type of utterance were examined according to the patient's race/ethnicity. The race/ethnic groups were European (nineteen), African American (eleven), Latino (thirty-four), and Asian (four). In 90 percent of the sessions, the resident and the patient were of different ethnicity. Residents used social connection utterances more with European ancestry patients, but used personal utterances more with Latino patients. Residents did not use open-ended questions or probes for patient understanding more with minority patients. The communication patterns observed in this study were similar to those reported in the literature. This study has limitations, but additional research may confirm that residents communicate differently with patients by race and could use more appropriate methods of dealing with cross-cultural situations. More research on cross-cultural communication is needed.

Adolescent↗