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Biomedical subjects

A E Athanasiou

Publications and source records attributed to A E Athanasiou.

At least 19 recordsLinked to original sources
PubMed2006

Primary bacteraemia caused by Rhizobium radiobacter in a patient with solid tumours.

A case of Rhizobium radiobacter primary bacteraemia in a patient with solid tumours is reported. Corticosteroid therapy and diabetes mellitus were the predisposing factors. The patient was treated successfully with amikacin and piperacillin/tazobactam. The clinical isolate was identified as R. radiobacter by 16S rRNA gene sequencing. Phytopathogenicity tests and a PCR assay demonstrated that the organism was not a plant pathogen.

Adult↗
PubMed2003

In vivo evaluation of two new moisture-resistant orthodontic adhesive systems: a comparative clinical trial.

OBJECTIVE: To evaluate and compare the clinical performance of two new moisture-resistant orthodontic adhesive systems: a chemically-cured composite resin (Unite, 3M Unitek, Monrovia, California, USA) in conjunction with a special moisture-resistant primer (Transbond MIP, 3M Unitek, Monrovia, California, USA); and a fluoride-releasing light-cured compomer (Assure, Reliance Orthodontic Products, Inc., Itasca, Illinois, USA). DESIGN: Randomized controlled clinical trial using the 'split-mouth' technique. SETTING: Department of Orthodontics, Aristotle University of Thessaloniki. SUBJECTS (MATERIALS) AND METHODS: Twenty-five consecutively started patients (13 females and 12 males) requiring fixed appliance orthodontic treatment. INTERVENTIONS: Four-hundred-and-thirty-six stainless steel brackets bonded to all teeth except molars using two different moisture-resistant orthodontic adhesive systems. MAIN OUTCOME MEASURES: Bond failure rates during a period of 9 months were estimated for each adhesive system and the corresponding bracket survival curves were plotted using the Kaplan- Meier product-limit estimate. Bracket survival distributions with respect to adhesive material, tooth location, patient's gender and operator, were then compared by means of a log-rank test. Bond failure interface was determined using the Adhesive Remnant Index. RESULTS: Assure recorded a higher bond failure rate (13.8 per cent) than Unite & MIP (7.3 per cent). The corresponding bracket survival curves were found to be significantly different (P < 0.05). Premolars exhibited higher bond failures than incisors and canines (P < 0.001), while half (49.8 per cent) of the total bond failures occurred during the first 2 months of treatment. The predominant mode of failure was within the bonding material. CONCLUSION: The new moisture-resistant adhesive systems under study were found to be clinically efficient, though Assure exhibited a significantly higher bond failure rate than Unite and Transbond MIP. The higher frequency of adhesive failures observed with Assure might indicate a possible weak point at the adhesive-bracket interface.

Adhesives↗
PubMed2002

In vivo evaluation of a moisture-activated orthodontic adhesive: a comparative clinical trial.

OBJECTIVES: To evaluate and compare the clinical performance of a water-activated, ethyl-cyanoacrylate adhesive to a conventional composite resin. The null hypothesis tested was that there was no difference in bracket survival distribution, over a period of orthodontic treatment, for brackets bonded with either bonding agent. DESIGN: Single center randomized controlled clinical study. SETTING AND SAMPLE POPULATION: Twenty-five consecutive patients (15 females and 10 males) were selected and treated with fixed appliances in a university postgraduate orthodontic clinic. All teeth, but the molars, were bonded with twin stainless steel brackets (n = 429) using a split-mouth technique and random allocation of the two adhesives. OUTCOME MEASURE: Bond failure rates during a period of 9 months were estimated for each adhesive system and the corresponding bracket survival curves were plotted using the Kaplan-Meier product-limit estimate. Bracket survival distributions with respect to adhesive material, tooth location, investigator, and bond failure interface were then compared by means of a log-rank test. Bond failure interface was determined using the Adhesive Remnant Index (ARI). RESULTS: The water-activated bonding material recorded a significantly higher bond failure (22.4%) than the composite resin (5.1%). There were also statistically significant differences in bracket survival distributions between the two adhesives (log-rank test: p < 0.001). Premolars exhibited higher bond failure rates than incisors and canines (p < 0001). The predominant mode of failure was within the bonding material. CONCLUSION: Further investigations focused on the improvement of the physical and mechanical properties of the water-activated bonding system are needed to make it a reliable alternative adhesive for the direct bonding of orthodontic brackets.

Adhesives↗
PubMed2001

Impact factor. A review with specific relevance to orthodontic journals.

The aim of this article is to address the issues of impact factor and circulation with reference to dental and orthodontic journals by discussing various parameters including language, citations, nature of published articles, and scientific domain. Examples from the literature are provided to illustrate the variability of impact factors among periodicals, based on the publicity and scientific area covered, and the impact factor scores are presented together with the circulation of orthodontic periodicals.

Bibliometrics↗
PubMed2000

Surface characterization of retrieved NiTi orthodontic archwires.

The structure and morphological condition of retrieved NiTi orthodontic archwires was evaluated and any possible alterations in the surface composition of the alloy following 1-6 months in vivo were characterized. NiTi wires (GAC, German Orthodontics, ORMCO) of various cross-sections were collected through a retrieval protocol and were subjected to multi-technique characterization. Optical microscopy revealed islands of amorphous precipitants and accumulated microcrystalline particles. Micro MIR-FTIR investigation of the retrieved samples demonstrated the presence of a proteinaceous biofilm, the organic constituents of which were mainly amide, alcohol, and carbonate. Scanning electron microscope and X-ray microanalysis showed that the elemental species precipitated on the material surface were Na, K, Cl, Ca, and P, forming NaCl, KCl, and Ca-P precipitates. Increased intra-oral exposure was consistently associated with the presence of a mature film, while evidence of alloy delamination, pitting, and crevice corrosion, as well as a notable reduction in the alloy grain size was observed. Intra-oral exposure of NiTi wires alters the topography and structure of the alloy surface through surface attack in the form of pitting or crevice corrosion or formation of integuments. Further in vivo research is required to resolve the implications of the described ageing pattern in the corrosion resistance of the alloy, the potential for nickel leaching, as well as bracket-archwire friction variants.

Alcohols↗
PubMed1999

Random errors in localization of landmarks in postero-anterior cephalograms.

The aim of the present study was to evaluate the random error in localization of the most common landmarks in postero-anterior cephalograms (PAC). The study took place at the Department of Orthodontics of Aarhus University during the period 1993-1995. The material consisted of 30 standardized PAC taken in natural head position. Five examiners had to identify 34 landmarks on each cephalogram. Subsequently, all examiners had to identify again the same 34 landmarks on one randomly selected cephalogram five times with a time interval of at least 24 hours. All landmarks were digitized, related to an X-Y co-ordinate system, and an arithmetical mean was calculated. The accuracy of digitizing was evaluated by digitizing one randomly selected cephalogram 10 times. The main findings of this study are: (1) The digitizing error is negligible compared to the errors introduced by landmark identification. (2) Each landmark has its own characteristic pattern of variance, which is very similar on both sides. (3) Significant differences in accuracy exist between the various postero-anterior landmarks. The six most accurate landmarks are mastoid left (l) and right (r), latero-orbitale (l) and (r), and antegonion (l) and (r). The six least accurate landmarks are coronoid (l) and (r), condylar (l) and (r), and mandibular foramen (l) and (r). (4) A significant difference in the accuracy of landmark identification between the five examiners was only seen for seven of the 34 landmarks. (5) No evidence was found that one examiner was consistently better/worse than the others. (6) No improvement in the accuracy was found after repeated identification, thus there seems to be no short-term 'learning process'. Refereed Paper

Cephalometry↗
PubMed1997

Clinical characteristics and properties of ceramic brackets: A comprehensive review.

The aim of this article is to provide the clinician with an up-to-date comprehensive literature review concerning the clinical characteristics and properties of ceramic brackets. The article critically presents and discusses the various aspects of ceramic brackets with regard to the types, physical properties, bond strength, frictional resistance, base surface characteristics, debonding techniques and enamel fracture risks, enamel abrasion and wear, bracket fracture, and bracket recycling. The article contains also guidelines and criteria concerning the specific applications and use of ceramic brackets.

Ceramics↗
PubMed1996

Transverse dentofacial structure of young men who have undergone surgical correction of unilateral cleft lip and palate: a posteroanterior cephalometric study.

The transverse dentofacial structure of 34 young adult males with unilateral cleft lip and palate, studied by means of posteroanterior cephalograms, was compared to that of a normal sample of 102 young adult males. All cleft patients had been treated surgically and orthodontically in accordance with a standardized protocol. Orthognathic surgical treatment was carried out when growth had ended in a few subjects. In studying the posteroanterior cephalograms, eight lengths, 10 ratios, and three angular variables were used. Comparison of the cephalometric values of the subjects with cleft palate and the normal sample of young adult males indicated (1) the absence of any significant differences in angular variables describing the transverse dentoalveolar relationships in the maxillary and mandibular incisal regions as well as the mandibular position; (2) the absence of any significant differences in the ratios of the nasal, maxillary, and mandibular widths to the interorbital width; (3) the presence, in the cleft group of significantly decreased ratios of maxillary intermolar width to interorbital width, mandibular intermolar width to interorbital width, maxillary intermolar width to mandibular intermolar width, and maxillary intermolar width to maxillary width; (4) the presence, in the cleft group, of a significantly increased ratio of innerorbital width to interorbital width; and (5) significant correlations between the maxillary and mandibular molar widths in the cleft group.

Adult↗
PubMed1996

Validity of computerized predictions of dentoskeletal and soft tissue profile changes after mandibular setback and maxillary impaction osteotomies.

The aim of the present investigation was to evaluate the validity of the predictions of a computerized cephalometric system (Dentofacial Planner) regarding dentoskeletal and soft tissue profile changes after mandibular setback and maxillary impaction osteotomies. Tracings of lateral cephalograms taken at the end of preoperative orthodontics (within 1 week before surgery) and approximately 1 year after the operation were digitized and entered into the Dentofacial Planner. For the mandibular setback group, the computerized predictions tended to place the mandible less posteriorly than the actual situation and to significantly underestimate the mandibular plane angle, the total anterior skeletal and soft tissue facial heights, the lower anterior skeletal facial height, and the upper lip height. In the maxillary impaction group, the prediction printouts significantly overestimated the total anterior soft tissue facial height, the upper lip height and the inclination and curvature of the lower lip and underestimated the soft tissue thickness in the regions of pogonion and point B.

Adolescent↗
PubMed1996

Short-term functional alterations in the stomatognathic system after orthodontic-surgical management of skeletal vertical excess problems.

The aim of the present investigation was to study the functional alterations in the stomatognathic system following orthodontic-surgical management of skeletal vertical excess problems. The sample comprised 43 patients who received combined orthodontic-surgical treatment including bilateral vertical ramus osteotomy for posterior repositioning and counterclockwise rotation of the mandible (n = 26) or Le Fort I osteotomy for maxillary impaction (n = 17). All subjects were examined within 1 week before operation and 6 months postsurgery. Methods of examination included: (a) evaluation of dysfunction by means of a clinical index, (b) measurement of mandibular range of motion, (c) assessment of the number and intensity of occlusal contacts, and (d) tomographic evaluation of condyle-fossa relationships. The results of the study indicated that postoperatively (a) there was an increase of patients with dysfunction in the mandibular osteotomy group and a decrease of patients with dysfunction in the maxillary osteotomy group; (b) the maximum interincisal opening decreased significantly in the mandibular osteotomy group; (c) there was a significant increase in the number and intensity of occlusal contacts in both groups; and (d) the shortest posterior and anterior interarticular distances increased significantly in the mandibular osteotomy group.

Adolescent↗
PubMed1996

Evaluation of impacted canines by means of computerized tomography.

The precise localization of impacted canines is of paramount importance in formulating the diagnosis and treatment plan. Conventional radiographic techniques for evaluating impacted canines have a major shortcoming, namely, the superimposition of all structures on the film, which often makes it difficult to distinguish detail. Computerized tomography provides excellent tissue contrast, eliminating blurring and overlapping of adjacent teeth.

Child↗
PubMed1994

Short-term consequences of orthognathic surgery on stomatognathic function.

Craniomandibular dysfunction, mandibular range of motion and occlusal contacts subsequent to surgical-orthodontic treatment were studied in 20 adults with Le Fort I impaction and/or advancement, 34 with vertical ramus setback, 12 with sagittal split advancement and 16 with Le Fort I impaction, and/or advancement and bilateral vertical ramus setback. All subjects were examined 1 week before surgery and 6 months post-operatively. The results of the study indicated that 6 months post-operatively: (a) There was a decrease (NS) in dysfunction patients in the maxillary and double-jaw osteotomy groups, and an increase in the mandibular advancement osteotomy sample (P < 0.05). (b) There was a significant decrease in maximal interincisal opening in both mandibular osteotomy groups (P < 0.01) and in laterotrusive movements in the mandibular advancement group (P < 0.05). (c) The number and intensity of occlusal contacts increased significantly in the maxillary and mandibular setback osteotomy groups (P < 0.01 and P < 0.001, respectively).

Adolescent↗
PubMed1994

Comparison of velopharyngeal growth patterns between cleft lip and/or palate patients requiring or not requiring pharyngeal flap surgery.

This investigation compares the patterns of velopharyngeal growth in cleft lip and/or palate patients. Those who had velopharyngeal competence and acceptable speech are compared with those who presented with velopharyngeal incompetence requiring pharyngeal flap surgery or prosthesis later. Lateral cephalograms of 30 cleft palate only (CPO), 35 unilateral cleft lip and palate (UCLP), and 20 bilateral cleft lip and palate (BCLP) children of the Lancaster Cleft Palate Clinic were studied. These records were taken at 6 month intervals during the first 2 postnatal years and annually thereafter up to 6 years of age. Soft tissue landmark points in the velopharyngeal region were digitized. Length and thickness of the soft palate and height and depth of the nasopharynx were measured. Evaluation of the growth curves of these four cephalometric variables indicated only two significant differences between children who later required pharyngeal flap surgery and those who did not. These differences were found in the growth in length of the soft palate of the CPO group and in the growth in depth of the nasopharynx of the BCLP group. Based on the present cephalometric data, it is impossible to predict at an early age those cleft lip and/or palate patients who will later require pharyngeal flaps.

Cephalometry↗
PubMed1994

Cephalometric evaluation of pharynx, soft palate, adenoid tissue, tongue, and hyoid bone following the use of a mandibular repositioning appliance in obstructive sleep apnea patients.

The aim of this study was to evaluate the pharynx, soft palate, adenoid tissue, tongue, and hyoid bone when a mandibular repositioning appliance was used for managing patients with obstructive sleep apnea. Lateral cephalograms of 45 adult obstructive sleep apnea patients from the Lancaster Cleft Palate Clinic were taken without the appliance and some days later with the device in the mouth. This device was used during sleep for improving patients' respiration. Twenty-four cephalometric variables were evaluated. When the appliance was in the mouth, significant alterations (P < .001) were observed in the distances: (a) between anterior and posterior pharyngeal walls at the level of the second and third cervical vertebrae, respectively; (b) between the most superior point of the tongue and the maxillary plane; and (c) between the hyoid bone and the mandibular plane, ramus plane, cervical vertebrae tangent, mandibular symphysis, gonion, and third and fourth cervical vertebrae. The results of this study indicate that significant changes in pharyngeal space, hyoid bone, and tongue positions take place in obstructive sleep apnea patients when a mandibular repositioning device is used.

Adenoids↗
PubMed1993

Morphologic and functional implications of the surgical-orthodontic management of mandibular prognathism: a comprehensive review.

The aim of this review is to present the various morphologic and functional implications of the surgical-orthodontic management of mandibular prognathism, thus providing a more complete determination of the efficacy of this modality of treatment. Major conclusions that can be drawn from the bibliography indicate that: (1) After treatment considerable improvement takes place on the soft tissue and dentoskeletal profile, occlusal tooth contacts, and temporomandibular joint function and and pain; (2) Surgical management of mandibular prognathism can be associated with decreased maximum interincisal opening; (3) Although immediately after surgery there is a tendency for the condyles to be distracted downward and anteriorly from their preoperative position, in long-term postsurgery the condyles, on the average, regain their initial position; (4) Compensatory alterations in the pharyngeal, suprahyoid, and infrahyoid muscular regions take place postoperatively; (5) Skeletal changes after mandibular setback to correct mandibular prognathism occur frequently, but their magnitude and patterns exhibit variation and are not necessarily detrimental; and (6) Fulfillment of expectations toward surgical-orthodontic management of mandibular prognathism was reported to be frequent.

Bite Force↗
PubMed1993

Evaluation of maxillary dental arch form in unilateral clefts of lip, alveolus, and palate from one month to four years.

This study evaluated the early changes of maxillary alveolar arches of operated unilateral cleft lip and palate patients. Dental casts were available at four age increments. Triangular flap cheiloplasty was carried out at an early age. Two-stage palatoplasty by vomer flap and soft palate closure took place later. Prior to lip repair, the alveolar arches were classified according to the relationship between greater and lesser segments. Almost a quarter had overlap of the alveolar segments with no contact between the alveolar ridges at the cleft site; some had no overlap with contact of the alveolar segments in the cleft region; almost a quarter had both overlap of the alveolar segments and contact; and almost half had no overlap of the segments and the alveolar ridges were not in contact at the cleft site. After lip repair, the arch relationships were examined and the percentage of patients in each of the four groups indicated a moulding effect of lip repair on the alveolar segments. This moulding effect caused the alveolar segments in most patients to be in contact at the cleft site. Most of these also had segment overlap. All patients were re-examined shortly after palatal repair. The trend for segment overlap and contact continued after palate surgery. However, when all patients were seen at age 4, percentages of patients in each group indicated that previous overlap of segments improved to a more desirable nonoverlapped relationship in approximately half of the patients. The other half continued to demonstrate arch collapse, in excess of what would be considered ideal ridge relationship.

Child, Preschool↗