Biomedical subjects

Athanasios E Athanasiou

Publications and source records attributed to Athanasios E Athanasiou.

11 recordsLinked to original sources

PubMed2007

Assessment of bisphenol-A release from orthodontic adhesives.

INTRODUCTION: The aim of this study was to quantitatively characterize the bisphenol-A (BPA) released from orthodontic adhesives after artificial accelerated aging. METHODS: A chemically cured, no-mix adhesive and a visible light-cured adhesive were bonded to 40 stainless steel brackets divided in 2 groups of 20 brackets each. In total, 3 series of specimens were prepared for each adhesive-bracket group. All specimens were immersed in alcohol to induce accelerated aging. Samples of eluent removed from each group at 1 day and at 1, 3, and 5 weeks after aging were processed with high-pressure liquid chromatography; all assays were performed in triplicate, and the results were averaged. RESULTS: No trace of BPA was identified for either adhesive across all time intervals, implying that, if present, the amount of BPA did not exceed the detection limit of the analytical technique (0.1 ppm or 0.1 microg/L). CONCLUSIONS: BPA release from light-cured or chemically cured, no-mix adhesives did not reach the 0.1 ppm level. Estrogenicity assays are required to clarify the potential estrogenicity of adhesives, whereas formulation of benzoic ring-free, high molecular weight monomers might eliminate the concerns associated with the use of Bis-GMA.

Analysis of Variance↗

PubMed2006

Premolar root changes following treatment with the banded herbst appliance.

AIM: The aim of this prospective study was to radiographically assess root morphology changes in maxillary and mandibular premolars following Herbst appliance treatment. PATIENTS AND METHODS: Twenty-five consecutive adolescents (19 boys and six girls, mean age 13.08 years) with Class II, Division 1 malocclusion were treated with the banded Herbst appliance for a mean period of 13.16 months. Periapical radiographs of the upper and lower premolars were obtained before appliance insertion and immediately after appliance removal using the parallel technique. All radiographs were scanned, digitized and analyzed using appropriately adjusted cephalometric software. The pre- and post-treatment length and area of the first and second maxillary and mandibular premolar roots were calculated. Statistical analysis included paired t-tests to evaluate pre- and posttreatment changes, and independent t-tests to compare the pre and post-treatment differences between the first and the second premolars, which served as controls. The level of significance was set at p <or= 0.05 for all tests. RESULTS: No statistically significant decrease in premolar root lengths or areas was noted following removal of the Herbst appliance. We observed a statistically-significant decrease in the root area of the first mandibular premolars compared to that of the second mandibular premolars. CONCLUSIONS: Although we observed no statistically-significant root morphology changes in the first and second premolars following Herbst appliance treatment, the mandibular first premolars revealed significantly more root resorption than did the mandibular second premolars.

Adolescent↗

PubMed2006

Orthodontic journals with impact factors in perspective: trends in the types of articles and authorship characteristics.

INTRODUCTION: The purposes of this study were to analyze the types of articles and their authorship characteristics in the 3 orthodontic journals with impact factors--American Journal of Orthodontics and Dentofacial Orthopedics (AJODO), Angle Orthodontist (AO), and European Journal of Orthodontics (EJO)--during 2 intervals of 5 years each (1993-1997 and 1998-2002) and to assess the changes in their contents during these periods. METHODS: The results of 3004 article entries were analyzed with the Pearson chi-square test, and the examination of the variability of the parameters studied among journals and across the 2 time intervals was performed at the 0.05 level of significance. RESULTS AND CONCLUSIONS: Significant differences were found between the journals with respect to the research component of articles (higher in the EJO) and case reports (higher in the AJODO and the AO). For each journal, differences were also identified between the 2 time intervals, with multi-authored papers and multiple affiliations appearing more frequently in the second interval. The contributions of articles from the United States and Canada to the AJODO and the AO were statistically higher than to the EJO. A similar trend was found for articles from Europe, which comprise more than 70% of the content of the EJO. An increased contribution of articles from East Asia and Oceania was noted in the second time interval, which reached almost 100% of the previous time frame. The potential sources of variation in the studied parameters are discussed.

Authorship↗

PubMed2005

Advanced orthodontic education: evolution of assessment criteria and methods to meet future challenges.

The achievement of academic and research institutes has increasingly become the subject of ranking by independent organizations. This trend has educational and economic implications, which may pertain to attracting students and endowments as well as allocating of funds to specific educational components. The aims of this article were to discuss the reliability and soundness of the existing academic ranking methods and to propose guidelines for the quantitative assessment of advanced orthodontic programs. This criteria-driven assessment assigns weight factors for the basic components of orthodontic education and provides a template for clarifying the standing of programs. Moreover, a combination of program and individual assessment is proposed to monitor the implementation of educational criteria and assess their effectiveness.

Accreditation↗

PubMed2005

Ethics and fraud in science: a review of scientific misconduct and applications to craniofacial research.

The purpose of this article is to review and discuss the occurrence of fraud in biomedical research and analyze the definition, origin, and various forms of scientific misconduct. Fraud in research most often involves reporting data for which no records of experiment or population are present; manipulating research materials, equipment, or procedures to arrive at the desirable result; adding, changing, or omitting results, which positively or negatively relate to the hypothesis that the research intends to test; and incorporating ideas, statements, procedures of others' work without permission and appropriate credit to the source. The etiologic factors contributing to this deviant behavior, and measures taken by relevant bodies to eliminate this phenomenon are discussed. Ethical and integrity aspects of craniofacial research are explored and a set of criteria to facilitate rigorous assessment of the integrity of clinical and basic research protocols is proposed. These include (1) an integrity-focused training of researchers to adhere to specific laboratory procedure and tactics which discourage fraud; (2) appointment of external reviewers to detect unusual and suspicious experimental process or data patterns; and (3) encouragement of multicenter trials. Although it is widely recognized that the sole determinant of scientific misconduct is the individual investigator's integrity, a number of precautions may effectively reduce the prevalence of this event, which may affect the status and trends of biomedical research in general.

Bioethical Issues↗

PubMed2004

Nickel content of as-received and retrieved NiTi and stainless steel archwires: assessing the nickel release hypothesis.

This study assesses the nickel content of as-received and retrieved stainless steel and NiTi archwires alloys. New and used brand-matched, composition-matched, and cross section-matched archwires were subjected to scanning electron microscopy and energy-dispersive electron probe microanalysis. Elemental analysis was performed on three randomly selected areas, and the nickel content, expressed as ratios of Ni/Ti (in NiTi wires) or Ni/Fe (in stainless steel), was statistically analyzed with a t-test (alpha = .05). No changes were detected with respect to Ni content ratios between as-received and retrieved NiTi or stainless steel wires, suggesting an absence of nickel release. Wear and delamination phenomena on the wire surface and the formation of galvanic couple between the stainless steel wires and bracket brazing materials intraorally may modify the corrosion susceptibility of the wire alloys in clinical conditions.

Corrosion↗

PubMed2003

Characterization of as-received, retrieved, and recycled stainless steel brackets.

AIM: The purpose of the present study was to investigate the composition and to assess the microhardness and structure of as received, retrieved, and recycled stainless steel brackets. MATERIALS AND METHODS: New, used, and recycled brand-, slot size-, and prescription-matched appliances were subjected to scanning electron microscopy (SEM), energy dispersive (EDS) electron probe microanalysis, metallographic analysis, and Vickers microhardness testing. Elemental analysis was performed on randomly selected bulk material base and wing areas. Basic metal content and microhardness results were statistically analyzed using a two-way ANOVA and the Tukey test, with treatment (as received, retrieved, and recycled) and bracket region (base, wing) serving as discriminating variables (alpha = 0.05). RESULTS: The results showed that there was no alteration in the bulk composition of the brackets among the three conditions. In contrast, differences were noted between bracket base and wing with respect to elemental composition among all groups, implying that the base and wings were manufactured from different alloys. The metallographic etching identified no difference in grain structure between the bracket base and wing components for all groups, regardless of treatment. Vickers microhardness demonstrated significant differences in hardness between base and wing for all groups and between recycled and retrieved states for the wing component.

Electron Probe Microanalysis↗

PubMed2003

Long-term assessment of psychologic outcomes of orthognathic surgery.

PURPOSE: This long-term study of post-orthognathic surgery patients aimed at assessing perceptions of problems with physical and psychologic functioning, self-concept, body image, and satisfaction with the surgical outcome based on subjective evaluations. In addition, the patient's perception of self-concept, body image, and function was compared with the perception of pretreatment patients and controls with no treatment need. PATIENTS AND METHODS: One hundred seventeen patients who underwent orthognathic surgery 10 to 14 years earlier and participated in a psychologic study 10 years earlier received questionnaires that were composed of 4 instruments designed to assess these factors. A sample of 92 persons representing a population without treatment need and 39 patients requesting treatment for a malocclusion served as control groups. RESULTS: The findings of this study support the hypothesis that improvement in appearance brought about by orthognathic surgery is associated with improvement in psychosocial adjustment. Orthognathic surgery resulted in subjective estimation of function, appearance, health, and interpersonal relationships that was higher than that among pretreatment and no-treatment control groups. The level of body image and self-esteem approximated but did not reach that of a nonpatient population. CONCLUSIONS: In view of the current psychologic and social environment, patients should be offered the appropriate treatment to correct a disfigurement if it is subjectively perceived by them as a handicap, in part to improve the psychologic outcome.

Adult↗

PubMed2002

In vivo aging of orthodontic alloys: implications for corrosion potential, nickel release, and biocompatibility.

Despite the large number of studies investigating nickel release from orthodontic stainless steel and nickel-titanium alloys, there is a lack of conclusive evidence with respect to the composition and kinetics of the corrosive products released. The objective of this review is to address the critical issues of corrosion potential and nickel leaching from alloys by investigating the effect of intraoral conditions on the surface reactivity of the materials. After an overview of fundamentals of metallurgical structure of orthodontic alloys, we provide an analysis of corrosion processes occurring in vivo. We present recent evidence suggesting the formation of a proteinaceous biofilm on retrieved orthodontic materials that later undergoes calcification. We illustrate the vastly irrelevant surface structure of in vivo- vs in vitro-aged alloys and discuss the potential implications of this pattern in the reactivity of the materials. Finally, we present a comprehensive review of the issue of nickel release, based on three perspectives: its biologic effects, the methods used for studying its release, and nickel-induced hypersensitivity in orthodontic patients.

Corrosion↗

PubMed2002

Nickel content of as-received, retrieved, and recycled stainless steel brackets.

The purpose of this study was to investigate the composition of as-received, retrieved, and recycled stainless steel brackets. New, used, and recycled brand-matched, slot size-matched, and prescription-matched appliances were subjected to scanning electron microscopy and energy dispersive electron probe microanalysis. Elemental analysis was performed on randomly selected surface bracket base and wing areas, and metal content was statistically analyzed with the 2-way ANOVA and the Tukey test, with treatment (as-received, retrieved, and recycled) and bracket regions (base and wing) serving as discriminating variables (alpha = 0.05). The results showed that there was no difference in the surface composition of the base; however, surface area-wing analysis indicated that nickel content was decreased in retrieved and recycled specimens, implying that an ionic release effect occurred in vivo. Differences were noted between bracket base and wing with respect to elemental composition for the same brackets, implying that the base and wings are manufactured from different alloys.

Analysis of Variance↗

PubMed2002

Three-dimensional craniofacial reconstruction imaging.

This review article aims to describe and discuss the imaging techniques most commonly used in medicine and dentistry to obtain three-dimensional images of the craniofacial complex. Three-dimensional imaging techniques provide extensive possibilities for the detailed and precise analysis of the whole craniofacial complex, for virtual (on-screen) simulation and real simulation of orthognathic surgery cases on biomodels before treatment, as well as for the detailed evaluation of the effects of treatment. Laser scanning in combination with the stereolithographic biomodeling seems to be a very promising combination for three-dimensional imaging, although there is still considerable room for improvement. Constant efforts should be made in the direction of developing and enhancing the existing techniques as well as exploring the potential for developing new methods based on emerging sectors of technology.

Cephalometry↗