Long-term impact of oral surgery with or without amoxicillin on the oral microbiome-A prospective cohort study.

Routine postoperative antibiotic prophylaxis is not recommended for third molar extractions. However, amoxicillin still continues to be used customarily in several clinical practices worldwide to prevent infections. A prospective cohort study was conducted in cohorts who underwent third molar extractions with (group EA, n = 20) or without (group E, n = 20) amoxicillin (250 mg three times daily for 5 days). Further, a control group without amoxicillin and extractions (group C, n = 17) was included. Salivary samples were collected at baseline, 1-, 2-, 3-, 4-weeks and 3 months to assess the bacterial shift and antibiotic resistance gene changes employing 16S rRNA gene sequencing (Illumina-Miseq) and quantitative polymerase chain reaction. A further 6-month follow-up was performed for groups E and EA. Seven operational taxonomic units reported a significant change from baseline to 3 months for group EA (adjusted p < 0.05). No significant change in relative abundance of bacteria and ß-lactamase resistance genes (TEM-1) was observed over 6 months for any group (adjusted p > 0.05). In conclusion, the salivary microbiome is resilient to an antibiotic challenge by a low-dose regimen of amoxicillin. Further studies evaluating the effect of routinely used higher dose regimens of amoxicillin on gram-negative bacteria and antibiotic resistance genes are warranted.

The communal consultation video-Enhancing learning and broadening experience through observing dialogue.

INTRODUCTION: This study presents a novel, student-centred, on-demand video learning modality that supports students as they transition from theory to clinical practice. Authentic, one-to-one teacher and student consultations have been video recorded and uploaded online for the peers and subsequent years of students to consume and learn from. This study describes the development and use of these communal consultation videos (CCVs), examines how students perceive this novel intervention and proposes supporting educational theory. METHODS: A library of 28 CCVs has been archived online, to enable learning for students not present at the original staff consultation. A questionnaire was designed and administered to evaluate student perceptions of this novel learning intervention and administered to see how students used and perceived its benefit. RESULTS: The CCV has proven to be popular, well received and valued by students. Students reported the videos were interactive, engaged them cognitively and supported them for assessments and in preparation for the clinical care of their own patients. Students also reported that watching the videos broadened their "clinical" experience of others cases that were different to their own. CONCLUSION: This novel learning modality demonstrates new engaging learning opportunities for students and teachers that support students for assessments and clinical skill practice and afford observational clinical experience.

A qualitative analysis of students' perceptions of videos to support learning in a psychomotor skills course.

INTRODUCTION: This qualitative study analysed students' experiences and perceptions about different types of videos in a psychomotor skills course, relating to clinical knowledge and skills and how they benefited learners in and out of the classroom. METHODS: Subjects were recruited from 4th and 5th year dental undergraduate programme. The recruitment was terminated after 24 students participated since data saturation was reached. A semi-structured interview was conducted with each participating student, digitally recorded and transcribed verbatim. A thematic analysis was performed using an inductive approach to identify key themes. RESULTS: Four key domains were identified from thematic analysis: functionality and access; learning and understanding; clinical skills preparation and performance and supplementary learning resources. Students perceived videos to be an important and vital learning tool relating to its on-demand access, control of functionality and use for particular needs that is not possible from textbooks or lectures. Video learning materials allows students to clarify knowledge, improve cognitive thinking and enhance revision of theoretical concepts and clinical skills. Two types of video were regarded as particularly useful as students reported being actively and cognitively engaged in the learning content and broadened their clinical experience. In addition, students reported mental preparation of clinical psychomotor skills using their own mental visualisation which enabled them to prepare for the clinical care of their patients. CONCLUSION: This qualitative research supports the benefits of learning from videos in relation to convenience of access and functionality of the videos. In addition, it shows novel aspects to learning from videos that are more cognitively engaging and in mental preparation of clinical skills prior to patient care.

Does the use of amoxicillin/amoxicillin-clavulanic acid in third molar surgery reduce the risk of postoperative infection? A systematic review with meta-analysis.

The objectives of this systematic review were to investigate the efficacy of amoxicillin/amoxicillin-clavulanic acid for reducing the risk of postoperative infection after third molar surgery and to evaluate the adverse outcomes in these patients, as well as in healthy volunteers. A systematic search of four databases was performed on May 26, 2017. Eleven studies qualified for the qualitative analysis and eight were found suitable for meta-analysis. The results suggest that both amoxicillin-clavulanic acid and amoxicillin significantly reduce the risk of infection after third molar extraction (overall relative risk (RR) 0.25, P<0.001). However, with the exclusion of randomized controlled trials with a split-mouth design (due to an inadequate crossover period after antibiotic treatment), only amoxicillin-clavulanic acid was found to be effective (RR 0.21, P<0.001). The risk of adverse effects was significantly higher in the amoxicillin-clavulanic acid group (RR=4.12, P=0.023) than in the amoxicillin group (RR 1.57, P=0.405). In conclusion, amoxicillin-clavulanic acid and amoxicillin may significantly reduce the risk of infection after third molar extraction. However, their use in third molar surgery should be viewed with caution, as recent clinical trials on healthy volunteers have shown evidence of the negative impact of amoxicillin use on bacterial diversity and antibiotic resistance.

Challenges in the transition to clinical training in dentistry: An ADEE special interest group initial report.

INTRODUCTION: Curricular integration in higher education has been widely supported in the educational literature. As a result, several health care and specifically dental curricula have evolved from compartmentalised disciplinary training to integrated modalities; however, in many courses, a pre-clinical-clinical watershed remains a barrier to integration in dental education. This article introduces a general description of the pre-clinical-clinical transition in dentistry according to the outcomes of the discussion held during the first working group session of the "Transition to Clinical Training" Special Interest Group during the 2016 annual meeting of the Association for Dental Education in Europe. MATERIALS AND METHODS: An online questionnaire was made available before the meeting to survey the curricular characteristics of the participants' schools. During the meeting, a working session related to the pre-clinical-clinical transition occurred. Conclusions from the discussion are summarised in this article. RESULTS: Fourteen dental schools from 12 countries participated in the online survey. The included programmes had an average duration of 5.3 years (SD = 0.48), with high school or the local equivalent as the required entrance level for dentistry. The hybrid curriculum was the leading curriculum design (n = 9) followed by competence-based curricula (n = 3), with patient treatment as the core of clinical training in every included programme. CONCLUSION: The pre-clinical-clinical transition in dentistry is a recognisable matter in dental education that requires assessment and research to ease the management of a stage with relevant influence on educational outcomes. This article presents an initial framework for further research and educational intervention.

Evaluation of peer-generated MCQs to assess and support learning in a problem-based learning programme.

PURPOSE: Problem-based learning (PBL) students report uncertainty on the depth and breadth of learning required, and this is a significant stressor and challenge. Student-generated MCQ questions were trialled and evaluated as a way to support depth and breadth of learning. METHODS: Students set MCQs relating to specified learning issues, and an analysis and evaluation of setting and answering the MCQs were performed. The Revised Study Process Questionnaire (R-SPQ-2F) and final written examination scores were correlated to question setting and answering. Students were asked to rate the impact of the MCQs on their learning in PBL. RESULTS: A total of 147 questions were created and 2373 answered. Students reported challenges with setting questions, although these made them think more deeply and helped their learning and affirming their learning progress. MCQs authored indicated significant associations with Understanding, and examination scores were associated with MCQs authored. Students reported a moderate response to how the MCQs supported their depth and breadth of learning. CONCLUSIONS: While MCQ setting was perceived as a useful learning exercise, students engaged to different levels and experienced challenges. Students were uncertain whether the MCQs helped clarify the depth and breadth of learning in PBL, as they were not clear whether the questions set by their peers were relevant to the required learning outcomes.

Elevated α-synuclein caused by SNCA gene triplication impairs neuronal differentiation and maturation in Parkinson's patient-derived induced pluripotent stem cells.

We have assessed the impact of α-synuclein overexpression on the differentiation potential and phenotypic signatures of two neural-committed induced pluripotent stem cell lines derived from a Parkinson's disease patient with a triplication of the human SNCA genomic locus. In parallel, comparative studies were performed on two control lines derived from healthy individuals and lines generated from the patient iPS-derived neuroprogenitor lines infected with a lentivirus incorporating a small hairpin RNA to knock down the SNCA mRNA. The SNCA triplication lines exhibited a reduced capacity to differentiate into dopaminergic or GABAergic neurons and decreased neurite outgrowth and lower neuronal activity compared with control cultures. This delayed maturation phenotype was confirmed by gene expression profiling, which revealed a significant reduction in mRNA for genes implicated in neuronal differentiation such as delta-like homolog 1 (DLK1), gamma-aminobutyric acid type B receptor subunit 2 (GABABR2), nuclear receptor related 1 protein (NURR1), G-protein-regulated inward-rectifier potassium channel 2 (GIRK-2) and tyrosine hydroxylase (TH). The differentiated patient cells also demonstrated increased autophagic flux when stressed with chloroquine. We conclude that a two-fold overexpression of α-synuclein caused by a triplication of the SNCA gene is sufficient to impair the differentiation of neuronal progenitor cells, a finding with implications for adult neurogenesis and Parkinson's disease progression, particularly in the context of bioenergetic dysfunction.

Journal-based learning, a new learning experience building on PBL at HKU.

OBJECTIVE: To evaluate the effectiveness of a new journal-based learning (JBL) programme designed to equip students with skills necessary to understand dental research publications, thereby preparing them for continuing professional development. MATERIALS AND METHODS: A baseline evaluation of knowledge relating to key research terms was conducted on 52 final-year BDS students. 11 weekly seminars were conducted from 8 clinical disciplines driven by a reading list of 2-5 journal articles along with a series of 'guidance' questions relating to research terms and content knowledge aspects of each paper to focus their reading and learning. Seminars were facilitated by discipline experts with supporting notes. An exit test based on research process and terminologies for the programme was conducted with 4 repeated questions from the baseline assessment. A systematic marking scheme was used and the results analysed. A focus group was run to collect feedback regarding students' views and experiences on the JBL experience. FINDINGS: Students showed significant improvements over the baseline score. The mean score rose from 3.5 to 11.5 in the repeated questions (P < 0.001). The focus group revealed that students had learnt new information about journal classification, evidence level determination, new research terms and the structure of research papers. From the first 4 years of PBL, students recognized the importance of learning from research papers since year 1. However, JBL gave them a deeper understanding of research and the development of critical appraisal skills. IMPLICATIONS: JBL provided final-year students the opportunity to learn significantly more about dental research, terminologies, paper structure, critical analysis and content knowledge through active-learning small group seminars.

Silver compounds used in dentistry for caries management: a review.

OBJECTIVE: Silver compounds have been used for their medical properties for centuries and in dentistry for more than a century. The aim of this review is to examine the evidence supporting the therapeutic use of silver in dentistry and the outcomes from the clinical trials, as well as mode of action and biocompatibility. DATA SOURCES: Literature was searched using the PubMed database between the year 1966 and 2011, with principle key terms such as "Silver Nitrate", "Silver Fluoride", "Silver Diammine Fluoride", "Silver compounds" and "Dental caries". Hand searching was performed for relevant papers cited in the indices back to the year 1905. RESULTS: In vitro, in vivo and clinical evidence have demonstrated that silver compounds are viable agents for preventing and arresting caries both in the primary and permanent dentition; however they are associated with adverse tooth discolouration and some reports that pulp irritation may occur. Further research has investigated its effectiveness as a dentine desensitiser, root canal disinfectant and even in silver impregnated restorative materials. The mode of action of silver compounds on carious tooth tissues is thought to include inhibition of the demineralization process, as well as an anti-bacterial effect by interference of bacterial cell membranes, cytoplasmic enzymes and inhibition of bacterial DNA replication. CONCLUSION: Silver compounds have been shown to be an effective anti-caries agent; however, there is an incomplete understanding of how silver compounds prevent caries. Further research is required to help identify its most efficacious use and limitations.

Self-perceived preparedness for dental practice amongst graduates of The University of Hong Kong's integrated PBL dental curriculum.

OBJECTIVES: To determine how prepared for dental practice graduates from the integrated problem-based learning (PBL) dental undergraduate curriculum at The University of Hong Kong (HKU) perceive themselves to be and to identify factors associated with self-perceived preparedness. MATERIALS AND METHODS: A postal questionnaire was sent to five cohorts of dentists who had graduated from HKU's integrated PBL curriculum between 2004 and 2008. Using a 4-point Likert scale, the questionnaire assessed the self-perceived level of preparedness in 59 competencies grouped in nine domains. Responses were dichotomised into 'poorly prepared' and 'well prepared'. RESULTS: The response rate was 66% (159/241). The mean proportion (±standard deviation) of respondents indicating well-preparedness was 72.0±15.1% overall, and for each domain was as follows: general patient management, 93.1±12.1%; practice management, 81.0±22.2%; periodontology and dental public health, 73.5±19.3%; conservative dentistry, 92.5±13.1%; oral rehabilitation, 62.8±24.0%; orthodontics, 23.0±32.9%; managing children and special-needs patients, 64.8±28.9%; oral and maxillofacial surgery, 52.2±25.2%; and drug and emergency management, 84.7±22.6%. The odds of self-perceived well-preparedness were increased for cohorts graduating in 2004 and 2005 and graduates working in a non-solo dental practice. CONCLUSIONS: Dental graduates of HKU's integrated PBL curriculum felt well prepared for the most fundamental aspects of dental practice. However, apparent deficiencies of training in orthodontics and oral and maxillofacial surgery will need to be addressed by continuing education, postgraduate training and planning for the new 6-year undergraduate curriculum in 2012.

Reaction of silver diamine [corrected] fluoride with hydroxyapatite and protein.

UNLABELLED: Silver diammine fluoride (SDF) is used as an anticaries agent; however, its mode of action is uncertain, whether chemical, physical, mechanical or antibacterial. As a preliminary study, the effect of SDF on hydroxyapatite (HAp) and gelatin (as a chemically-representative protein) was examined. METHODS: 2.5mg HAp powder specimens and 0.5mL 10% gelatin (Riedel-de Haën) (initially as a sol at ∼37°C), were mixed with 0.5mL of 38% SDF (J. Morita), 4% NaF (Sigma) or 40% AgNO(3) (Sigma) and tumbled in 1.5mL polypropylene tubes (Sarstedt) for 48h at ∼23°C, in two series: exposed to laboratory lighting, and kept dark at all times. The HAp specimens were separated by centrifugation and decanting, then these and one set of gelatin specimens were dried at 60°C in situ; a second parallel set of gelatin specimens were dried at ∼23°C. Each was washed with 1mL deionized water for 1min, 3 times. Treated materials were observed, before and after washing, with scanning and transmission electron microscopy (SEM, TEM); energy-dispersive X-ray analysis (EDX), and electron diffraction (ED). RESULTS: SDF appeared to produce globular particles of CaF(2) on the surface of the HAp, but these disappeared on washing, whilst with AgNO(3) yellow cubic crystals of Ag(3)PO(4) formed which were not dissolved on washing, but which darkened, converting gradually to metallic silver, on exposure to light. NaF had no effect on gelatin, whilst with SDF and AgNO(3), particles of silver were produced which were resistant to washing. CONCLUSIONS: Both principal components of tooth tissue react with SDF; the solubility of the putative CaF(2) formed weakens the case for it exerting a caries-protective effect. The importance of the persistent silver needs further study.

Assessment of the use of problem-orientated, small-group discussion for learning of a fixed prosthodontic, simulation laboratory course.

AIM: To evaluate a simulation laboratory course that used student-centred small-group problem-orientated discussion activities as the main medium of instruction. METHODS: A structured questionnaire using a six-point Likert scale with 30 statements relating to a fixed prosthodontics course was distributed to 4th-year and 5th-year students who had completed the course. RESULTS: A 93% response rate was achieved for both years with a mean score for the 4th-year being 94.2 (+/- 13.7) and the 5th-year 107.5 (+/-16.9). The differences between the scores of both years are highly significant (P = 0.0006) indicating that the 5th-year were more favourable about the course and learning approach used. Consistency and reliability of the questionnaire was judged reliable according to Cronbach's alpha (4th-year = 0.7, 5th-year = 0.83). Many aspects of the small-group student-centred activities were highly valued by students however, students expressed a preference for learning and interacting with teachers than colleagues. CONCLUSION: Small-group student-centred learning activities were reported as creating an active, safe learning environment with beneficial opportunities for peer-peer interaction such as questioning, teaching and learning from students. However, students expressed a preference for teacher-centred information dissemination and activities. An understanding of the rationale of student dependence to teacher-centred learning may allow improved modifications in a student-centred learning environment.

Fractional inhibitory concentration index of combinations of antibacterial agents against cariogenic organisms.

OBJECTIVES: To examine the inhibitory effects between paired combinations of four antibacterial agents that have been investigated in dentistry against six bacteria associated with dentinal caries. METHODS: The antibacterial agents tested were: chlorhexidine dihydrochloride, benzalkonium chloride, cetrimide and cetylpyridinium chloride. Two organisms each belonging to Streptococcus, Lactobacillus and Actinomyces species were evaluated against these agents. A checkerboard microtitration method was used to determine the minimum inhibitory concentration and fractionary inhibitory concentration (FIC) and summation operator FIC index of the paired combinations of antibacterial agents against the six species of bacteria. Appropriate controls were included. The summation operator FIC index was then used to determine if synergy, antagonism, or indifference occurred as a result of interactions between the antibacterial agents and the test organisms. RESULTS: The data from a total of 295 test results were evaluated. Using summation operator FIC values for synergy as < or = 0.5 and antagonism as > 4.0 as recommended by The American Society for Microbiology, no significant synergistic or antagonistic interactions were observed between the paired antibacterial agents when tested against selected organisms. However, a tendency for an additive antibacterial effect was observed with approximately a third of the test results. Nonetheless, no combination of antibacterial agents appeared to be superior to any other. CONCLUSIONS: According to these in vitro results, there appears to be no beneficial effect of combining the antibacterial agents against the individual cariogenic micro-organisms selected. However, it may be beneficial to use combined antibacterial agents that have a broader range of activity against an ecosystem of bacteria than using individual agents.

The minimum inhibitory concentration of oral antibacterial agents against cariogenic organisms.

The minimum inhibitory concentrations (MIC) of eight common dental antibacterial agents against three genera of bacteria which have been implicated in dentine caries, namely streptococci, lactobacilli and actinomycetes were investigated. The ultimate aim was to determine the most appropriate antibacterial agent which could be added to dental restorative materials for filling cavities where there was residual dentine caries. The antibacterial agents tested were chlorhexidine diacetate, chlorhexidine dihydrochloride, chlorhexidine gluconate, benzalkonium chloride, cetrimide, cetylpyridinium chloride, thymol and sodium hypochlorite. Thymol and sodium hypochlorite did not inhibit microbial growth at any of the concentrations tested. For the active antibacterial agents tested the MIC values against lactobacilli and streptococci were 0.25 microg/ml to 8.0 microg/ml and for actinomycetes 0.125 to 8.0 microg/ml. These results illustrate the wide spectrum of sensitivity of caries associated bacteria against dental antibacterial agents. From the MIC values alone, it is difficult to recommend which of the active antibacterial agents would be most effective in eliminating cariogenic organisms.

Two-unit cantilevered resin-bonded fixed partial dentures--a retrospective, preliminary clinical investigation.

PURPOSE: The aim of this study was to retrospectively evaluate the clinical retention and abutment movement of 2-unit cantilevered resin-bonded fixed partial dentures (FPD) that were inserted at Prince Philip Dental Hospital in Hong Kong. MATERIALS AND METHODS: Of 45 patients who were identified from a hospital computer search after receiving a 2-unit cantilevered resin-bonded FPD, 31 were clinically examined (33 FPDs). For each patient the following data were recorded: gender, age, cementation date, endodontic treatment if performed, bone support, tooth mobility, and FPD tipping or drifting. Data about any debonds with subsequent treatment and patient satisfaction on a 10-point scale were also recorded. RESULTS: The mean service life for the 33 prostheses was 30 +/- 18 months, with a range of 72 days to 67 months. One prosthesis debonded, resulting in a clinical retention rate of 97%. No rotation, drifting, or tipping was observed for any of the prostheses during the short period of this study. CONCLUSION: Two-unit cantilevered resin-bonded FPDs are successful in the short term, but further research is required to determine if they offer a viable alternative to fixed-fixed resin-bonded FPD designs.

Embedded problem-based learning of a clinical subject.

A problem-based learning approach was used for the 'teaching' of a fourth-year bridge course in an attempt to improve student learning and academic performance in the clinical environment. The introduction of problem-based learning requires careful planning as to the desired educational objectives and design.