Does prior knowledge affect interaction dynamics and learning achievement in digital problem-based learning? A pilot study.

Objective: Previous research on problem-based learning (PBL) describes that videotaped observations develop meaningful insights into cognitive processes in tutorial groups. Analysis regarding the amount of prior knowledge on learning achievement has not been investigated in medical education so far, although both are key factors of PBL success. Thus, we intended to analyse videos of digital problem-based learning (dPBL) sessions, focusing on knowledge acquisition and interaction dynamics among groups with different levels of prior knowledge to reveal any distinctions. Methods: This study employed a pilot design by dividing 60 dental students into twelve subgroups with less or more prior knowledge, determined by a pre-semester multiple choice test (MCQ). The groups engaged in videotaped dPBL cases, which were examined regarding group interactions and tutor effectiveness. The learning achievement was assessed through a post-semester MCQ, an oral and practical exam. Results: The video analysis showed that dPBL groups with less prior knowledge achieved significantly higher tutor effectiveness and group interaction utterances, but that the percentage of time in which utterances occurred was similar in both groups. Related to the MCQ results, the students with less prior knowledge learned four times more than those with profound previous abilities, but no significant difference was found in the results of the oral exam and practical exam. Conclusions: The interaction dynamics in dPBL depend on the group's amount of prior knowledge. Especially groups including participants with less prior knowledge seemed to benefit from dPBL in comparison to groups with more prior knowledge. The dPBL groups acquired knowledge in different ways during the courses but, finally, all students arrived at a similar level of knowledge.

A 23-Year Observational Follow-Up Clinical Evaluation of Direct Posterior Composite Restorations.

The purpose of this observational follow-up clinical study was to observe the quality of posterior composite restorations more than 23 years after application. A total of 22 patients, 13 male and 9 female (mean age 66.1 years, range 50-84), with a total of 42 restorations attended the first and second follow-up examinations. The restorations were examined by one operator using modified FDI criteria. Statistical analysis was performed with the Wilcoxon Mann-Whitney U test and Wilcoxon exact matched-pairs test with a significance level of p = 0.05. Bonferroni-Holm with an adjusted significance level of alpha = 0.05 was applied. With the exception of approximal anatomical form, significantly worse scores were seen for six out of seven criteria at the second follow-up evaluation. There was no significant difference in the first and second follow-up evaluations in the grades of the restorations with regard to having been placed in the maxilla or mandible, as well as for one-surface or multiple-surface restorations. The approximal anatomical form showed significantly worse grades at the second follow-up when having been placed in molars. In conclusion, the study results show that significant differences regarding FDI criteria in posterior composite restorations occur after more than 23 years of service. Further studies with extended follow-up time and at regular and short time intervals are recommended.

Influence of mechanical and chemical pre-treatments on the repair of a hybrid ceramic.

OBJECTIVES: This study aimed to investigate the influence of the respective mechanical and chemical pre-treatments on the composite repair of a CAD/CAM hybrid ceramic using a microtensile bond strength test (µTBS). METHODS: 15 CAD/CAM Blocks of Vita Enamic (VE) were randomly sectioned into three mechanical pre-treatments: (1.) Diamond bur (D), (2.) Airborne abrasion (A), (3.) Tribochemical silica coating (T) and subsequently five chemical pre-treatments: (1.) Clearfil SE Bond Bond (B; negative control), (2.) ESPE Sil (S), (3.) Clearfil Ceramic Primer Plus (CPP), (4.) Clearfil Repair (CR) and (5.) Scotchbond Universal (SCB). Per block, n = 20 specimens were sawn. Half of the specimens were randomly selected and subjected to an immediate bond strength test, while the other half was subjected to artificial aging for 6 months 180 days at 37 °C and subsequent thermocycling of 5000 cycles. A µTBS was performed and data (MPa) were compared in one-way and two-way ANOVA and Tukey's HSD. Paired-t-test was used for artificial aging (α = 0.05). Debonded specimens were analyzed of for failure modes with a stereomicroscope (SEM). RESULTS: The results of one-way ANOVA for the fifteen fastening procedures after aging indicated significant differences according to SCB-A and CPP-T. Two-way ANOVA after aging observed inferior bond strength for SCB. No differences were observed for mechanical pre-treatments. Artificial aging showed a significant reduction in bond strength on most of the fastening procedures. SIGNIFICANCE: SCB showed the lowest bond strength values besides B, S, CPP, and CR. MDP and silane are both suitable for the repair of VE.

3D printed versus commercial models in undergraduate conservative dentistry training.

INTRODUCTION: The treatment of carious lesions is one of the most fundamental competencies in daily dental practice. However, many commercially available training models lack in reality regarding the simulation of pathologies such as carious lesions. 3D printed models could provide a more realistic simulation. This study provides an exemplary description of the fabrication of 3D printed dental models with carious lesions and assesses their educational value compared to commercially available models in conservative dentistry. MATERIALS AND METHODS: A single-stage, controlled cohort study was conducted within the context of a curricular course. A stereolithographic model was obtained from an intraoral scan and then printed using fused deposition modelling. These models were first piloted by experts and then implemented and compared against commercial models in a conservative dentistry course. Experts and students evaluated both models using a validated questionnaire. Additionally, a cost analysis for both models was carried out. RESULTS: Thirteen dentists and twenty-seven 5th year dental students participated in the study. The 3D printed models were rated significantly more realistic in many test areas. In particular, the different tactility and the distinction in colour was rated positively in the 3D printed models. At 28.29€ (compared to 112.36€), the 3D printed models were exceptionally cost-efficient. CONCLUSIONS: 3D printed dental models present a more realistic and cost-efficient alternative to commercial models in the undergraduate training of conservative dentistry.

The Influence of Modified Experimental Dental Resin Composites on the Initial In Situ Biofilm-A Triple-Blinded, Randomized, Controlled Split-Mouth Trial.

The purpose of the study was to investigate the bacterial viability of the initial biofilm on the surface of experimental modified dental resin composites. Twenty-five healthy individuals with good oral hygiene were included in this study. In a split-mouth design, they received acrylic splints with five experimental composite resin specimens. Four of them were modified with either a novel polymeric hollow-bead delivery system or methacrylated polymerizable Irgasan (Antibacterial B), while one specimen served as an unmodified control (ST). A delivery system based on Poly-Pore® was loaded with one of the active agents: Tego® Protect 5000 (Antiadhesive A), Dimethicone (Antiadhesive B), or Irgasan (Antibacterial A). All study subjects refrained from toothbrushing during the study period. Specimens were detached from the splints after 8 h and given a live/dead staining before fluorescence microscopy. A Friedman test and a post hoc Nemenyi test were applied with a significance level at p < 0.05. In summary, all materials but Antibacterial B showed a significant antibacterial effect compared to ST. The results suggested the role of the materials' chemistry in the dominance of cell adhesion. In conclusion, dental resin composites with Poly-Pore-loaded active agents showed antibacterial effectiveness in situ.

The effect of new anti-adhesive and antibacterial dental resin filling materials on gingival fibroblasts.

OBJECTIVE: Aim of this study was to evaluate the biocompatibility of four experimental antiadhesive and antibacterial dental filling composites on human gingival fibroblasts (HGFs). METHODS: For these experimental resin composites a delivery system based on novel polymeric hollow beads, loaded with Tego Protect (Aa1), Dimethicone (Aa2), Irgasan (Ab1) and methacrylated polymerizable Irgasan (Ab2) as active agents was used. The cultured HGFs' cell integrity, proliferation, viability, collagen synthesis and cytokine release were measured. For this purpose, human gingival fibroblasts were treated with eluates from all four composites and compared with an experimental standard composite (ST). Eluate extraction times 24 h and 168 h were chosen. RESULTS: Statistical analysis was conducted via a mixed model. Both antibacterial composites reduced proliferation, collagen and cytokine synthesis significantly (p < 0.05), increasing with time of elution. Ab1 did also have a damaging effect on the membrane and on cell viability. SIGNIFICANCE: Overall, it can be concluded that the antiadhesive composites showed clear advantages over the antibacterial composites in terms of biocompatibility. This study also continues to show the potential of the new poly-pore system, as it can be used for a variety of other applications in future composite mixtures.

A multicentric survey to evaluate preclinical education in Endodontology in German-speaking countries.

AIM: To evaluate preclinical education in Endodontology at Austrian, German and Swiss dental schools using an online survey. METHODOLOGY: An online survey divided into nine categories was sent using SurveyMonkey software to 37 dental schools, before the spread of the COVID-19 pandemic. The questionnaire included 50 questions to evaluate preclinical endodontic education, such as faculty-to-student ratios, topics taught and materials used, in preclinical phantom head courses. Seven and 14 days after the first e-mail contact, dental schools received a reminder e-mail. After four and six weeks, the dental schools were contacted by telephone and asked to participate in the online survey. The processing time was eight weeks in total. RESULTS: The response rate was 89%. Preclinical endodontic education at the participating dental schools differs considerably. Theory classes ranged from 1 to 70 h (15 h mean), and practical classes ranged from 3 to 78 h (39 h mean). The faculty-to-student ratio varied between 1:4 and 1:38 (1:15 mean). Forty-five per cent of the dental schools had a specialist in endodontics teaching theory. Several dental microscopes were available for preclinical teaching purposes at 82% of the dental schools. The majority (82%) taught root canal preparation with rotary or reciprocating NiTi instruments. Overall, 85% of the dental schools taught lateral compaction, amongst other methods, for canal filling. CONCLUSION: A substantial divergence amongst the dental schools regarding the time dedicated to theory and practical instruction in Endodontology was reported. However, convergence in the use of root canal treatment techniques and materials was reported.

Impact of 0.1% octenidine mouthwash on plaque re-growth in healthy adults: a multi-center phase 3 randomized clinical trial.

OBJECTIVES: To investigate plaque inhibition of 0.1% octenidine mouthwash (OCT) vs. placebo over 5 days in the absence of mechanical plaque control. MATERIALS AND METHODS: For this randomized, placebo-controlled, double-blind, parallel group, multi-center phase 3 study, 201 healthy adults were recruited. After baseline recording of plaque index (PI) and gingival index (GI), collection of salivary samples, and dental prophylaxis, subjects were randomly assigned to OCT or placebo mouthwash in a 3:1 ratio. Rinsing was performed twice daily for 30 s. Colony forming units in saliva were determined before and after the first rinse. At day 5, PI, GI, and tooth discoloration index (DI) were assessed. Non-parametric van Elteren tests were applied with a significance level of p < 0.05. RESULTS: Treatment with OCT inhibited plaque formation more than treatment with placebo (PI: 0.36 vs. 1.29; p < 0.0001). OCT reduced GI (0.04 vs. placebo 0.00; p = 0.003) and salivary bacterial counts (2.73 vs. placebo 0.24 lgCFU/ml; p < 0.0001). Tooth discoloration was slightly higher under OCT (DI: 0.25 vs. placebo 0.00; p = 0.0011). Mild tongue staining and dysgeusia occurred. CONCLUSIONS: OCT 0.1% mouthwash inhibits plaque formation over 5 days. It therefore can be recommended when regular oral hygiene is temporarily compromised. CLINICAL RELEVANCE: When individual plaque control is compromised, rinsing with octenidine mouthwash is recommended to maintain healthy oral conditions while side effects are limited.

Feedback in medical education - a workshop report with practical examples and recommendations.

Background: As a teaching method, feedback is an integral part of medical education. However, there is a lack of a uniform theoretical basis or generally recognized guidelines for its specific design. Against this background, the aim of this article is to discuss conceptual considerations and empirical findings regarding feedback using various practical examples. Procedure and conceptual considerations: Building on the results of a workshop of the Committee for Communicative and Social Competences of the Society for Medical Education (GMA), this article first explains central conceptual considerations and empirical results on the topic of feedback. A particular focus is on various variables that influence the effect of feedback. This includes the feedback source, the frequency of feedback, starting points of feedback, the connection between feedback and reflection as well as the motivation and meta-cognitive skills of the feedback recipient. Practical examples: The implementation of feedback in practice is illustrated using eight examples from the field of medical and dental education. They stem from various settings and the focus is on formative oral feedback. It will become evident that the focus is more on the givers of feedback than the recipients of feedback. Instructions for recipients of feedback on how to reflect on it is still the exception. Discussion: Many of the relevant aspects for the effect of feedback described in the literature are already taken into account in the practical examples discussed. In conclusion, seven recommendations are made for implementing feedback in practice.

Adaptation and validation of the Berlin questionnaire of competence in evidence-based dentistry for dental students: a pilot study.

BACKGROUND: The purpose of this pilot study was to create a valid and reliable set of assessment questions for examining Evidence-based Dentistry (EbD) knowledge. For this reason, we adapted and validated for dental students the Berlin Questionnaire (BQ), which assesses Evidence-based Medicine (EbM) abilities. METHODS: The Berlin Questionnaire was validated with medical residents. We adapted it for use in a dentistry setting. An expert panel reviewed the adapted BQ for content validity. A cross-sectional cohort representing four training levels (EbD-novice dental students, EbD-trained dental students, dentists, and EbM-/EbD-expert faculty) completed the questionnaire. A total of 140 participants comprised the validation set. Internal reliability, item difficulty and item discrimination were assessed. Construct validity was assessed by comparing the mean total scores of students to faculty and comparing proportions of students and faculty who passed each item. RESULTS: Among the 133 participants (52 EbD-novice dental students, 53 EbD-trained dental students, 12 dentists, and 16 EbM-/ EbD-expert faculty), a statistically significant (p < 0.001) difference was evident in the total score corresponding to the training level. The total score reliability and psychometric properties of items modified for discipline-specific content were acceptable. Cronbach's alpha was 0.648. CONCLUSION: The adapted Berlin Questionnaire is a reliable and valid instrument to assess competence in Evidence-based Dentistry in dental students. Future research will focus on refining the instrument further.

Cytotoxicity of Self-Etch Versus Etch-and-Rinse Dentin Adhesives: A Screening Study.

Six dentin adhesives were tested in vitro regarding their cytotoxicity on human fibroblasts. The adhesives Hybrid Bond, One-up Bond F Plus, AdheSE, Clearfil SE Bond, Optibond Solo Plus and Syntac were eluted with culture medium as single or sequentially applied adhesive part for 24 h. 75 Petri dishes were produced per group. They were evaluated triangulated, comprising the quantitative evaluation (105 ones) to determine "viable", "dead" and "debris" cells with the use of a cell-counter and the reactivity index was also identified based on the qualitative assessment (420 ones). One-up Bond F Plus, AdheSE and Clearfil SE Bond showed a statistical difference of viable cells to the cell control. For One-up Bond F Plus, statistically, differences compared to hybrid bond and Syntac were also found. All the adhesives except One-up Bond F Plus showed significant differences between single and sequentially applied adhesive part regarding the quantitative evaluation. The test material showed a moderate grade of cytotoxicity. As a result, a statistically significant difference of the cytotoxicity between the self-etch and etch-and-rinse adhesives cannot be demonstrated regarding the qualitative evaluation and the reactivity index, but the differences between sequentially applied and single applied components can be proved.

Students' self-assessment of competencies in the phantom course of operative dentistry.

INTRODUCTION: The aim was to assess the competencies of undergraduate students in their roles of dental expert, scholar, communicator, collaborator, health advocate, manager and professional. MATERIALS AND METHODS: For this retrospective, pseudonymised observational study (pre-/post-testing), students in two cohorts in their first clinical semester in operative dentistry were asked to judge their competencies (1 = very good to 6 = insufficient) with a learning objective catalogue designed at the Goethe University Frankfurt (modelled after the National Competency-Based Learning Objective Catalogue Dentistry), at the beginning and end of their phantom course. In order to relate the students' subjective competency judgements to objective evidence of their skills, at the end of the semester their marks from the summative Objective Structured Practical Examination (OSPE) were compared with the subjective judgement of their exam performance before the final results were known. RESULTS: The reliability of the evaluation sheet was evaluated with Cronbach's alpha 0.98. The students judged their competencies as "sufficient" (4.23 ± 0.51) at the beginning and "satisfactory" (2.82 ± 0.43) at the end. A significant improvement in competencies was observed within all roles. The students' subjective judgement of the exam results (3.66 ± 0.62) was significantly correlated with the actual marks (3.69 ± 0.83) in the OSPE at 0.3547 (P = 0.0015). CONCLUSION: The evaluation instrument showed excellent reliability. The students judged that their competencies significantly increased during the semester. The triangulation with the actual marks in the context of an OSPE demonstrated a significant correlation with the students' exam judgements.

Work shadowing in dental teaching practices: evaluation results of a collaborative study between university and general dental practices.

BACKGROUND: The aim of this study was to investigate the acceptance and assessment of work shadowing carried out by students and dentists in dental practices. Furthermore, the extent to which students perceive an improvement in their specialised, communication and social competencies, was to be examined. METHODS: 61 dental students in their clinical semesters at a German university participated in work shadowing placements at 27 different general dental practices. Before beginning, they received checklists of various competencies that they self-assessed using school grades (from 1 = 'very good', to 6 = 'failed'), which they also repeated after completion. The dentists supplemented this with their external assessments. In addition, the students were requested to fill out a 54-item questionnaire and compose a freely-structured report after the work shadowing; the dentists filled out a questionnaire containing 16 items. The statistical analysis was carried out by means of the Friedman Test, including a post-hoc test (Bonferroni-Holm correction). RESULTS: The analysis showed a significant overall improvement in the students' self-assessed competencies by 0.71* ± 0.43 grades. With an average of 0.33* ± 0.36, the dentists' external assessment proved significantly higher than the self-assessment. The greatest improvements were perceived by the students in the areas of accounting (1.17* ± 0.77), practice organisation (1.05* ± 0.61) and dentist's discussions (0.94* ±0.80) [*p < 0.05]. The students confirmed experiencing an expansion of knowledge, an improvement in their communication skills and indicated a high degree of satisfaction in regard to the dentists (school grade 1.58 ± 0.93). A maximum amount of satisfaction towards the work shadow students was demonstrated by the dentists, and this form of teaching was assessed with a school grade of 1.69 ± 0.89. CONCLUSION: Both students and dental practitioners demonstrated a high level of satisfaction in regard to the work shadowing. The students felt their knowledge had increased, viewed the dentists as motivating role models and acknowledged a significant improvement in their specialised, communication and social competencies. Work shadowing in dental teaching practices presents a sensible addition to academic teaching at a university.

Cross-year peer-assisted learning using the inverted ("flipped") classroom design: A pilot study in dentistry.

BACKGROUND: The inverted classroom model (ICM) represents a special combination of online and attendance learning. The implementation of the didactic concept of "peer-assisted learning" (PAL) within an ICM design has not yet been described in the literature for the field of restorative dentistry. OBJECTIVE: It was the goal of the present study to develop an ICM offering in a cross-year PAL format (ICM-cyPAL), and then introduce and evaluate it. METHOD: The pilot project was conducted at the dental clinic at the Goethe University of Frankfurt/Main, where following its conceptual development and implementation with three consecutive cohorts of students in their first clinical semester (the sixth semester at university) the ICM-cyPAL offering was evaluated. Data on acceptance, tutor effectiveness, group interaction models and learning strategies were collected using an evaluative instrument. RESULTS: 121 students (tutees) participated in three cohorts. The response rate reached 98.3 %. In total, the offering was given an average rating of 6.97±1.93 (from 1 = unsatisfactory to 10 = excellent). As the tutees explained the attention that the tutors employed gave to the group was "just right" (4.65±1.04; where 1 = too controlling and 4 = just right to 7 = left the group on their own too long) and talked "just the right amount" (4.54±0.95; where 1 = too much and 4 = just right to 7 = talked too little). The results for tutor effectiveness reached values between 3.26±0.94 and 3.78±0.87; for the evaluation of group interaction models average values were obtained from 3.41±0.98 to 3.89±0.73 (on a Likert scale of 1 = do not at all agree to 5 = completely agree). Concerning the surveyed learning strategies, the dimensions of "resource management" and "implementation of the learning materials" were given the highest and lowest rankings, respectively. CONCLUSION: The tutees' ratings of the newly developed and implemented ICM-cyPAL offering in the dental context were mainly positive. The thematic orientation of the structured training program needs to be optimized. The offering itself requires both a high degree of organization and solid financial and staffing resources.

[Conception and implementation of a novel E-learning module with EbM learning contents in operative dentistry]. / Konzeption und Implementierung eines neuartigen E-Learning-Moduls mit EbM-Lerninhalten im Fach Zahnerhaltungskunde.

PURPOSE: Computer-assisted learning (CAL) programs are becoming more widely used in medical and dental training. However, the combination of CAL programs and evidence-based education in dentistry has not been described previously. The aim was to determine the acceptance and user-friendliness of a CAL program combined with evidence-based training. METHODS: The didactic concept of the module includes the case-oriented, problem-based embedding of a total of 32 EbM learning assignments, which can be completed interactively and self-determinedly in an interdisciplinary context using focus patients with different diseases. The present study was conducted at the Dental School of the Goethe University in Frankfurt/Main. Data on acceptance and user-friendliness were collected from three consecutive cohorts of 114 dental students attending their first clinical semester. They used the "Toothache Walk-in Clinic: FOCUS" CAL, which can be downloaded via the Internet. The instrument consisted of 64 statements. The first part addressed general information about the user. The second part contained 43 specific statements on the CAL program. These included factors A (handling and technical aspects), B (content and functional range), and C (didactics and suitability for education). Possible responses ranged from 0 to 3 (0 = strongly disagree, 3 = strongly agree). RESULTS: All of the 114 questionnaires distributed were returned (response rate 100%). Most users (90.1%) considered the topics of evidence-based dentistry important for their training. They rated the program by using German school grades, and the overall rating was 2.26 (SD = 0.64). Most students (88.6%) considered the program useful for their clinical training in the treatment of patients. The mean scores for the 43 specific items amounted to 1.90 (factor A, SD = 0.63), 1.55 (factor B, SD = 1.93), and 2.23 (factor C, SD = 0.79). CONCLUSIONS: The CAL program with dental medicine vignettes and learning elements for evidence-based medicine received a primarily positive assessment. Students welcome that EbM contents are offered as part of their dental studies curriculum.

Comparison of the shaping ability of RaCe, FlexMaster, and ProFile nickel-titanium instruments in severely curved root canals.

BACKGROUND: This in vitro study compared the shaping ability of RaCe, FlexMaster, and ProFile rotary nickel-titanium instruments in severely curved root canals of extracted teeth. MATERIAL AND METHODS: Sixty maxillary molars with curvatures ranging from 25° to 65° were embedded in a muffle system and portioned into five horizontal sections (thickness 1.2 mm), starting from the apex. Canals were divided into three groups (n = 20, each) and were prepared with RaCe, FlexMaster, or ProFile rotary nickel-titanium instruments and the TriAuto ZX handpiece using a crown-down preparation technique. We evaluated the difference between pre- and postoperative root canal cross-sections, loss of working length, instrument failure, and preparation time. The root canal area before and after the intervention was determined using an area-measuring software. The data were analyzed statistically using a one-way ANOVA followed by a Kruskal-Wallis multiple-comparison Z-value test. RESULTS: Specimens treated with FlexMaster showed the greatest change from preoperative cross-sections, followed by RaCe and ProFile. The cross-sectional changes induced by RaCe and FlexMaster preparation differed significantly from those produced by ProFile. Loss of working length, instrument failure, and preparation time did not differ significantly between the groups. CONCLUSIONS: Root canal preparation with the three instruments did not lead to any significant alteration of the original root anatomy or working length. Thus, we conclude that RaCe, FlexMaster, and ProFile instruments are of comparable efficiency and usefulness in the preparation of severely curved root canals. Key words:Endodontics, root canal preparation, rotary, extracted teeth, nickel-titanium.

Study on the Interrater Reliability of an OSPE (Objective Structured Practical Examination) - Subject to the Evaluation Mode in the Phantom Course of Operative Dentistry.

INTRODUCTION: The aim of the study presented here was to evaluate the reliability of an OSPE end-of-semester exam in the phantom course for operative dentistry in Frankfurt am Main taking into consideration different modes of evaluation (examiner's checklist versus instructor's manual) and number of examiners (three versus four). METHODS: In an historic, monocentric, comparative study, two different methods of evaluation were examined in a real end-of-semester setting held in OSPE form (Group I: exclusive use of an examiner's checklist versus Group II: use of an examiner's checklist including an instructor's manual). For the analysis of interrater reliability, the generalisability theory was applied that contains a generalisation of the concept of internal consistency (Cronbach's alpha). RESULTS: The results show that the exclusive use of the examiner's checklist led to higher interrater reliability values than the in-depth instructor's manual used in addition to the list. CONCLUSION: In summary it can be said that the examiner's checklists used in the present study, without the instructor's manual, resulted in the highest interrater reliability in combination with three evaluators within the context of the completed OSPE.

Regulator of Calcineurin 1 in Periodontal Disease.

Nuclear factor of activated T-cells (NFAT) and NF-kB pathway associated processes are involved in the pathogenesis of various inflammatory disorders, for example, periodontal disease. The activation of these pathways is controlled by the regulator of calcineurin 1 (RCAN1). The aim of this study was to elucidate the role of RCAN1 in periodontal disease. Healthy and inflamed periodontal tissues were analyzed by immunohistochemistry and immunofluorescence using specific rabbit polyclonal anti-RCAN1 antibodies. For expression analysis human umbilical vein endothelial cells (HUVEC) were used. HUVEC were incubated for 2 h with Vascular Endothelial Growth Factor (VEGF) or with wild type and laboratory strains of Porphyromonas gingivalis (P. gingivalis). Expression analysis of rcan1 and cox2 was done by real time PCR using specific primers for rcan1.4 and cox2. The expression of rcan1 was found to be significantly suppressed in endothelial cells of chronically inflamed periodontal tissues compared to healthy controls. Rcan1 and cox2 were significantly induced by VEGF and wild type and laboratory P. gingivalis strains. Interestingly, the magnitude of the rcan1 and cox2 induction was strain dependent. The results of this study indicate that RCAN1 is suppressed in endothelial cells of chronically inflamed periodontal tissues. During an acute infection, however, rcan1 seems to be upregulated in endothelial cells, indicating a modulating role in immune homeostasis of periodontal tissues.

Evaluating differently tutored groups in problem-based learning in a German dental curriculum: a mixed methods study.

BACKGROUND: It is still unclear to what extent the PBL tutor affects learning in PBL-sessions. This mixed-methods study (Part 1 and 2) evaluated the effects of facilitative (f) versus non-facilitative (nf) tutoring roles on knowledge-gain and group functioning in the field of endodontics. METHODS: Part 1 was a quantitative assessment of tutor effectiveness within a prospective, experimental, single-blind, stratified, randomized, two-group intervention study. Participants attended PBL in the context of a hybrid curriculum. A validated questionnaire was used and knowledge assessments were conducted before and after the intervention. External observers rated tutor performance. Part 2 was a qualitative assessment of tutor effectiveness and consisted of semi-structured expert interviews with tutors and focus group discussions with students. RESULTS: Part 1: f tutors obtained significantly higher scores than nf tutors with respect to learning motivation and tutor effectiveness (p ≤ 0.05). nf tuition resulted in a slightly larger knowledge gain (p = 0.08). External observers documented a significantly higher activity among facilitative tutors compared to non-facilitative tutors. Part 2: Tutors found the f role easier although this led to a less autonomous working climate. The students rated f tutoring as positive in all cases. CONCLUSIONS: With respect to PBL-group performance, students felt that groups guided in a non-facilitative fashion exhibited a higher level of independence and autonomy, especially with increasing PBL experience. In addition, students reported that more preparation was necessary for sessions guided by a non-facilitative tutor. Tutors were able to modify their role and influence group processes in a controlled manner. Results are useful for future "Train-the-Teacher" sessions.

Gold Nanoparticle-Mediated Delivery of Molecules into Primary Human Gingival Fibroblasts Using ns-Laser Pulses: A Pilot Study.

Interaction of gold nanoparticles (AuNPs) in the vicinity of cells' membrane with a pulsed laser (λ = 532 nm, τ = 1 ns) leads to perforation of the cell membrane, thereby allowing extracellular molecules to diffuse into the cell. The objective of this study was to develop an experimental setting to deliver molecules into primary human gingival fibroblasts (pHFIB-G) by using ns-laser pulses interacting with AuNPs (study group). To compare the parameters required for manipulation of pHFIB-G with those needed for cell lines, a canine pleomorphic adenoma cell line (ZMTH3) was used (control group). Non-laser-treated cells incubated with AuNPs and the delivery molecules served as negative control. Laser irradiation (up to 35 mJ/cm²) resulted in a significant proportion of manipulated fibroblasts (up to 85%, compared to non-irradiated cells: p < 0.05), while cell viability (97%) was not reduced significantly. pHFIB-G were perforated as efficiently as ZMTH3. No significant decrease of metabolic cell activity was observed up to 72 h after laser treatment. The fibroblasts took up dextrans with molecular weights up to 500 kDa. Interaction of AuNPs and a pulsed laser beam yields a spatially selective technique for manipulation of even primary cells such as pHFIB-G in high throughput.