Photocatalytic degradation of methyl orange by CeO2 and Fe-doped CeO2 films under visible light irradiation.

Undoped CeO2 and 0.50-5.00 mol% Fe-doped CeO2 nanoparticles were prepared by a homogeneous precipitation combined with homogeneous/impreganation method, and applied as photocatalyst films prepared by a doctor blade technique. The superior photocatalytic performances of the Fe-doped CeO2 films, compared with undoped CeO2 films, was ascribed mainly to a decrease in band gap energy and an increase in specific surface area of the material. The presence of Fe(3+) as found from XPS analysis, may act as electron acceptor and/or hole donor, facilitating longer lived charge carrier separation in Fe-doped CeO2 films as confirmed by photoluminescence spectroscopy. The 1.50 mol% Fe-doped CeO2 film was found to be the optimal iron doping concentration for MO degradation in this study.

Highly efficient photocathodes for dye-sensitized tandem solar cells.

Thin-film dye-sensitized solar cells (DSCs) based on mesoporous semiconductor electrodes are low-cost alternatives to conventional silicon devices. High-efficiency DSCs typically operate as photoanodes (n-DSCs), where photocurrents result from dye-sensitized electron injection into n-type semiconductors. Dye-sensitized photocathodes (p-DSCs) operate in an inverse mode, where dye-excitation is followed by rapid electron transfer from a p-type semiconductor to the dye (dye-sensitized hole injection). Such p-DSCs and n-DSCs can be combined to construct tandem solar cells (pn-DSCs) with a theoretical efficiency limitation well beyond that of single-junction DSCs (ref. 4). Nevertheless, the efficiencies of such tandem pn-DSCs have so far been hampered by the poor performance of the available p-DSCs (refs 3, 5-15). Here we show for the first time that p-DSCs can convert absorbed photons to electrons with yields of up to 96%, resulting in a sevenfold increase in energy conversion efficiency compared with previously reported photocathodes. The donor-acceptor dyes, studied as photocathodic sensitizers, comprise a variable-length oligothiophene bridge, which provides control over the spatial separation of the photogenerated charge carriers. As a result, charge recombination is decelerated by several orders of magnitude and tandem pn-DSCs can be constructed that exceed the efficiency of their individual components.

Teaching and assessment of implant dentistry in undergraduate and postgraduate education: a European consensus.

This paper constitutes a summary of the consensus documents agreed at the First European Workshop on Implant Dentistry University Education held in Prague on 19-22 June 2008. Implant dentistry is becoming increasingly important treatment alternative for the restoration of missing teeth, as patients expectations and demands increase. Furthermore, implant related complications such as peri-implantitis are presenting more frequently in the dental surgery. This consensus paper recommends that implant dentistry should be an integral part of the undergraduate curriculum. Whilst few schools will achieve student competence in the surgical placement of implants this should not preclude the inclusion of the fundamental principles of implant dentistry in the undergraduate curriculum such as the evidence base for their use, indications and contraindications and treatment of the complications that may arise. The consensus paper sets out the rationale for the introduction of implant dentistry in the dental curriculum and the knowledge base for an undergraduate programme in the subject. It lists the competencies that might be sought without expectations of surgical placement of implants at this stage and the assessment methods that might be employed. The paper also addresses the competencies and educational pathways for postgraduate education in implant dentistry.

Assessment of knowledge and competencies related to implant dentistry in undergraduate and postgraduate university education.

Learning in academic settings is strongly related to the way the students are tested or examined. Assessment therefore must be integrated in the curriculum design, coordinated and should reflect the learning outcomes of the education. Assessment within the field of implant dentistry must fulfil four major objectives: complete and direct the learning process with feedback (formative), ensure that students are adequately prepared (summative), assess attitudes and skills such as critical thinking, reflection and self-assessment ability, and supply continuous feedback to teachers on curricular content and impact. Different assessment methods should be used to assess different levels of competencies throughout the curriculum. Various forms of written or oral assessment methodologies are applicable at earlier stages in the curriculum. At intermediate levels, interactive assessment methods, such as patient simulations (paper based or virtual) and more could encourage the necessary synthesis of several disciplines and aspects of the theoretical knowledge. At higher levels of competence, documentation of clinical proficiency by means of reflective portfolios and diaries is an appropriate assessment method with both formative and summative potential. The highest level of competence requires performance assessment using structured, objective, clinical criteria. The group strongly encourages the use of reflective forms of assessment methods which engage the students in a process of self-appraisal, identification of individual learning needs and self-directed learning. The ultimate goal of this would be to allow the student to develop a lifelong learning attitude.

The global network on dental education: a new vision for IFDEA.

The advent of globalization has changed our perspectives radically. It presents increased understanding of world affairs, new challenges and exciting opportunities. The inequitable distribution and use of finite energy resources and global warming are just two examples of challenges that can only be addressed by concerted international collaboration. Globalization has become an increasingly important influence on dentistry and dental education. The International Federation for Dental Educators and Associations (IFDEA) welcomes the challenges it now faces as a player in a complex multifaceted global community. This report addresses the new circumstances in which IFDEA must operate, taking account of the recommendations made by other working groups. The report reviews the background and evolution of IFDEA and describes the extensive developments that have taken place in IFDEA over the past year with the introductions of a new Constitution and Bylaws overseen by a newly established Board of Directors. These were the consequence of a new mission, goals and objectives for IFDEA. An expanded organization is planned using http://www.IFDEA.org as the primary instrument to facilitate the exchange of knowledge, programmes and expertise between colleagues and federated associations throughout the world, thereby promoting higher standards in oral health through education in low-, middle- and high-income countries of the world. Such aspirations are modified by the reality and enormity of poverty-related global ill health.

Curriculum content, structure and ECTS for European dental schools. Part II: methods of learning and teaching, assessment procedures and performance criteria.

This paper presents a brief context of dental undergraduate curricular structure and content and lays out the Association for Dental Education in Europe's views on requirements and recommendations for learning, teaching and assessment procedures/performance.

Curriculum structure and the European Credit Transfer System for European dental schools: part I.

This paper presents a proposed curriculum structure and system of European Credit Transfer (ECTS) for undergraduate dental schools throughout Europe. It is the result of the work of a Taskforce ('Taskforce II'), appointed by DentEd, a thematic network of European dental schools and the Association for Dental Education in Europe (ADEE). There has been pan-European discussion of the document in draft stages (it was distributed to 200 dental schools) and following amendment, it was agreed formally at the National Assembly of ADEE in Athens, Greece, in September 2005. The main elements of the paper relate to: (i) a description of the framework proposed with relevance to the Bologna recommendations and common directive on recognition for professional qualifications as they apply to Dentistry; (ii) the structure of an undergraduate dental curriculum; (iii) student exchange and ECTS. In addition, the paper presents a series of requirements, guidelines and recommendations for action. ADEE expects that the 'requirements' proposed will be followed by dental schools in Europe, whilst the 'guidelines' and 'recommendations' also provided are open to local interpretation. The paper is also published on the ADEE website.

Computer-mediated instructional video: a randomised controlled trial comparing a sequential and a segmented instructional video in surgical hand wash.

BACKGROUND: Video-based instructions for clinical procedures have been used frequently during the preceding decades. AIM: To investigate in a randomised controlled trial the learning effectiveness of fragmented videos vs. the complete sequential video and to analyse the attitudes of the user towards video as a learning aid. MATERIALS AND METHODS: An instructional video on surgical hand wash was produced. The video was available in two different forms in two separate web pages: one as a sequential video and one fragmented into eight short clips. Twenty-eight dental students in the second semester were randomised into an experimental (n = 15) and a control group (n = 13). The experimental group used the fragmented form of the video and the control group watched the complete one. The use of the videos was logged and the students were video taped whilst undertaking a test hand wash. The videos were analysed systematically and blindly by two independent clinicians. The students also performed a written test concerning learning outcome from the videos as well as they answered an attitude questionnaire. RESULTS: The students in the experimental group watched the video significantly longer than the control group. There were no significant differences between the groups with regard to the ratings and scores when performing the hand wash. The experimental group had significantly better results in the written test compared with those of the control group. There was no significant difference between the groups with regard to attitudes towards the use of video for learning, as measured by the Visual Analogue Scales. Most students in both groups expressed satisfaction with the use of video for learning. CONCLUSION: The students demonstrated positive attitudes and acceptable learning outcome from viewing CAL videos as a part of their pre-clinical training. Videos that are part of computer-based learning settings would ideally be presented to the students both as a segmented and as a whole video to give the students the option to choose the form of video which suits the individual student's learning style.

A comparative evaluation of computer literacy amongst dental educators and students.

A task-oriented questionnaire was designed, aiming to quickly assess competence with the use of computers. The questionnaire consisted of distinct computer-related skills, representing various competences in educational computer use. A total score from 0 to 49 was calculated upon completion of the questionnaire, based on the sum of all the positively identified competences. The questionnaire was distributed to an international group of leading dental educators during the DentEd Global Congress in Prague in 2001 and to a cohort of first year dental students (2001) in the Dental Faculty, University of Malmo, Sweden. Certain attitudes towards the role of information and communication technology (ICT) in dental education were also measured through Visual Analogue Scales in the educator's group. A total of 149 questionnaires were collected from the educators' group and 58 from the dental students. There was no significant difference in the average computer competence score between the two groups. The educators' group average score was 20.7 (SD 9.9) and students' average was 18.1 (SD 8.5). A significant positive correlation (r = 0.395277, P < 0.0001) was found between the competence measured by the questionnaire and the year of graduation in the educators' group. The attitudes towards the role of ICT in dental education amongst the educators were very positive, regardless of their competence with computers, year of graduation or academic position. The results from this study indicate that there is wide diversity in computer competence amongst both students and academic staff. In addition, students' actual competence in the use of computers might not be as high as is often perceived through self-assessment and ordinal scales.

Simulation of patient encounters using a virtual patient in periodontology instruction of dental students: design, usability, and learning effect in history-taking skills.

Simulations are important educational tools in the development of health care competence. This study describes a virtual learning environment (VLE) for diagnosis and treatment planning in oral health care. The VLE is a web-based, database application where the learner uses free text communication on the screen to interact with patient data. The VLE contains forms for history taking, clinical images, clinical data and X-rays. After reviewing the patient information, the student proposes therapy and makes prognostic evaluations of the case in free text. A usability test of the application was performed with seven dental students. The usability test showed that the software responded with correct answers to the majority of the free text questions. The application is generic in its basic functions and can be adapted to other dental or medical subject areas. A randomised controlled trial was carried out with 39 students who attended instruction in history taking with problem-based learning cases, lectures and seminars. In addition, 16 of the 39 students were randomly chosen to practise history taking using the virtual patient prior to their first patient encounter. The performance of each student was recorded on video during the patient sessions. The type and order of the questions asked by the student and the degree of empathy displayed towards the patient were analysed systematically on the videos. The data indicate that students who also undertook history taking with a virtual patient asked more relevant questions, spent more time on patient issues, and performed a more complete history interview compared with students who had only undergone standard teaching. The students who had worked with the virtual patient also seemed to have more empathy for the patients than the students who had not. The practising of history taking with a virtual patient appears to improve the capability of dental students to take a relevant oral health history.

A prospective, randomized, comparative clinical study of resin composite and glass ionomer cement for retrograde root filling.

OBJECTIVE: To compare the clinical and radiographic treatment outcome of retrograde root filling with either dentin-bonded resin composite (Retroplast, RP) or glass ionomer cement (Chelon-Silver, CS). STUDY DESIGN: A prospective, randomized clinical study of 134 consecutive patients with indication of retrograde root filling of an incisor, canine, premolar, or first molar. Either RP or CS was chosen at random as retrograde filling material. Either material was applied onto the entire resection surface after prepared slightly concave. This preparation technique makes a sealing of the entire resection surface possible and prevents marginal contraction gaps during polymerization. A total of 122 patients were available for 1-year follow-up. RESULTS: After 1 year the proportion of successful cases was significantly higher in the RP group (73%) than in the CS group (31%) (p<0.001). Doubtful healing with a need for a longer observation period was seen in 17% of the RP cases and 19% of the CS cases. The proportion of failures in the RP group (10%) was significantly lower than that in the CS group (50%) (p<0.001). Most of the unsuccessful CS cases failed due to loosening of the retrograde filling. CONCLUSIONS: Dentin-bonded RP applied onto the entire, slightly concave resection surface is a predictable apical sealant characterized by a high success rate. In contrast, retrograde root filling with CS results in an unacceptably high failure rate due to insufficient bonding strength to the concave resection surface.

Computer literacy and attitudes among students in 16 European dental schools: current aspects, regional differences and future trends.

A questionnaire survey was carried out to investigate the competence and attitude of dental students towards computers. The current study presents the findings deriving from 590 questionnaires collected from 16 European dental schools from 9 countries between October 1998 and October 1999. The results suggest that 60% of students use computers for their education, while 72% have access to the Internet. The overall figures, however, disguise major differences between the various universities. Students in Northern and Western Europe seem to rely mostly on university facilities to access the Internet. The same however, is not true for students in Greece and Spain, who appear to depend on home computers. Less than half the students have been exposed to some form of computer literacy education in their universities, with the great majority acquiring their competence in other ways. The Information and Communication Technology (ICT) skills of the average dental student, within this limited sample of dental schools, do not facilitate full use of new media available. In addition, if the observed regional differences are valid, there may be an educational and political problem that could intensify inequalities among professionals in the future. To minimize this potential problem, closer cooperation between academic institutions, with sharing of resources and expertise, is recommended.

A virtual classroom for undergraduate periodontology: a pilot study.

The Integrated Distributed Learning Environments or virtual classrooms constitute a new promising structure in education of health care personnel. A virtual classroom was developed aiming to teach periodontology to an international group of 28 dental students using a problem-based learning (PBL) approach. The course was web-based and included synchronous and asynchronous communication, on-line libraries and multimedia material. Students were organised in 4 independent groups and each group was appointed a tutor. The results of the study indicate that one of the most positive effects students experienced was competence in using the computer. They also rated highly the use of multimedia for learning of clinical procedures. It was found that web boards and email were too slow to allow group work in the virtual classroom. Real time communication programs were found to be superior for problem discussion and hypothesis formulation. However, email and the web board played a significant role during certain steps of the PBL method. The students expressed a positive attitude for the combined use of network-based learning and problem-based education. Our present experience suggests that distance learning should be organised with a mixture of different media, allowing communication of knowledge and skills between the resources and the students, as well as cooperation between the students. Computer literacy among teachers and students is limited and should be enhanced. Finally, personal contact between the resource persons and the students before the distant learning course commences helps the learning process.

Local CD-ROM in interaction with HTML documents over the Internet.

The internet and computer assisted learning have enhanced the possibilities of providing quality distance learning in dentistry. The use of multimedia material is an essential part of such distance learning courses. However the Internet technology available has limitations regarding transmission of large multimedia files. Therefore especially when addressing undergraduate students or geographically isolated professionals, large download times make distance learning unattractive. This problem was technically solved in a distance learning course for undergraduate students from all over Europe. The present communication describes a method to bypass the problem of transmitting large multimedia files by the use of a specially designed CD-ROM. This CD-ROM was run locally on the students' PC interacting with HTML documents sent over the Internet.

Analgesic dose-response relationship of ibuprofen 50, 100, 200, and 400 mg after surgical removal of third molars: a single-dose, randomized, placebo-controlled, and double-blind study of 304 patients.

The purpose of this single-dose, randomized, placebo-controlled, and double-blind study was to evaluate the analgesic dose-response relationship of 50-mg, 100-mg, 200-mg, and 400-mg doses of ibuprofen after third molar surgery. Patients were instructed to take a single dose of either placebo or 50 mg, 100 mg, 200 mg, or 400 mg of ibuprofen when the postoperative pain was moderate to severe. Acetaminophen 500 mg was used as a rescue medication. Pain intensity, pain relief, and any possible adverse events were recorded on self-administered questionnaires hourly for 6 hours after intake of study medication. If rescue medication was taken, the time of intake was registered. A total of 304 patients entered the study, and 258 complied with the protocol. A positive analgesic dose-response relationship of 50-mg, 100-mg, 200-mg, and 400-mg doses of ibuprofen was observed when evaluated by pain intensity difference, sum of pain intensity difference, pain relief, total pain relief, and survival distribution of patients not taking rescue medication. Although significant pain relief was seen after a dose of 50 mg ibuprofen, ibuprofen 400 mg provided maximum pain relief and the longest duration of analgesic effect. Mild transient adverse events were reported by 6.8% of the patients. However, there was no significant difference in frequency between the placebo and 50 mg, 100 mg, 200 mg, and 400 mg ibuprofen dose groups.

Marginal bone level after Le Fort I osteotomy.

The object of the study was to assess the effect of Le Fort I osteotomy and maxillary interdental osteotomy on the marginal bone level. Forty patients (25 female, 15 male, mean age 24 years, range 15-46) treated for dentofacial deformities comprised the subjects of the study and underwent Le Fort I osteotomy with or without simultaneous interdental osteotomy. Outcome was measured by marginal bone level measured in radiographs before and 1 year after operation. All patients had good oral hygiene. There was an overall significant mean marginal bone loss of 0.2 mm at surfaces without interdental osteotomy (P = 0.001). When the bone loss of the different types of teeth was considered separately, only those of central incisors (0.5 mm, P = 0.0001) and canines (0.4 mm, P = 0.004) were significant. Interdental osteotomy caused an overall mean marginal bone loss of 0.4 mm, but this was not significantly different from that of teeth without interdental osteotomy (P = 0.07). When the bone loss of different types of teeth after interdental osteotomy was considered separately, the only difference that achieved significance was that of premolars (0.3 mm, P = 0.04). Though there were significant differences, none of them was large enough to have any clinical relevance. Le Fort I osteotomy and interdental osteotomy may only in a few instances cause marginal bone loss of clinical relevance. However, the present study was performed on patients with good oral hygiene. The above conclusions may therefore not be valid for patients who, prior to surgery, already have a compromised marginal bone level.

Pitfalls in orthognathic model surgery. The significance of using different reference lines and points during model surgery and operation.

The planning of orthognathic surgery usually involves a simulation of jaw movements in a semi-adjustable articulator. The use of vertical and horizontal references during model surgery and operation have previously been described in great detail. The purpose of the present study was to quantify the errors resulting from using different reference lines and points in model surgery and operation. The results indicate that clinically significant differences between the planned and surgical jaw movement can result from the erroneous transfer of reference lines and points between model surgery and operation. Solutions to some of the problems discussed are suggested.