Residual Bacteriome after Chemomechanical Preparation of Root Canals in Primary and Secondary Infections.

INTRODUCTION: Secondary infections may be linked to the presence of residual microorganisms within dental root canals. The purpose of this study was to investigate the bacterial composition of primary and secondary root canal infections before and after chemomechanical treatment. METHODS: Samples were collected before chemomechanical preparation (S1) and before obturation (S2) from 19 subjects (10 primary and 9 secondary infections). DNA was extracted, and the V3/V4 region of the 16S ribosomal RNA gene was amplified using the 347 F/803R primers and paired-end sequenced using the MiSeq (Illumina, San Diego, CA) instrument. RESULTS: Sequencing analysis yielded partial 16S ribosomal RNA gene sequences that were taxonomically classified into 10 phyla and 143 genera. The most prevalent phyla in the S1 and S2 samples were Firmicutes and Bacteroides; however, when comparing between sample groups, Proteobacteria seem to have been enriched in secondary infections. The dominant genera in the primary S1 samples were Bacillus, Streptococcus, and Prevotella, whereas Bacillus, Streptococcus, and Selenomonas dominated the secondary infection S1 samples. Bacillus and Marinilactibacillus were the most dominant genera in the primary and secondary S2 samples. The mean number of operational taxonomic units per sample was 32,656 (±12,124 SD) and 37,113 (±16,994 SD) in the S1 and S2 samples, respectively. Alpha and beta diversities presented the same pattern within samples from both groups. CONCLUSIONS: Great interindividual variations in the bacterial composition of the root canal biofilms were observed. There was no difference in the bacterial composition before and after treatment, although some genera survived and seem to be part of a residual microbiome. Our findings revealed a high diversity of the bacterial communities present in root canal infections after chemomechanical treatment, although the majority of the taxa detected were in low abundance.

Exploring the Presence of Core Skills for Surgical Practice Through Simulation.

OBJECTIVE: The ability to simulate procedures in silico has transformed surgical training and practice. Today's simulators, designed for the training of a highly specialized set of procedures, also present a powerful scientific tool for understanding the neural control processes that underpin the learning and application of surgical skills. Here, we examined whether 2 simulators designed for training in 2 different surgical domains could be used to examine the extent to which fundamental sensorimotor skills transcend surgical specialty. DESIGN, SETTING & PARTICIPANTS: We used a high-fidelity virtual reality dental simulator and a laparoscopic box simulator to record the performance of 3 different groups. The groups comprised dentists, laparoscopic surgeons, and psychologists (each group n = 19). RESULTS: The results revealed a specialization of performance, with laparoscopic surgeons showing the highest performance on the laparoscopic box simulator, while dentists demonstrated the highest skill levels on the virtual reality dental simulator. Importantly, we also found that a transfer learning effect, with laparoscopic surgeons and dentists showing superior performance to the psychologists on both tasks. CONCLUSIONS: There are core sensorimotor skills that cut across surgical specialty. We propose that the identification of such fundamental skills could lead to improved training provision prior to specialization.

Early assessment with a virtual reality haptic simulator predicts performance in clinical practice.

Background: Prediction of clinical training aptitude in medicine and dentistry is largely driven by measures of a student's intellectual capabilities. The measurement of sensorimotor ability has lagged behind, despite being a key constraint for safe and efficient practice in procedure-based medical specialties. Virtual reality (VR) haptic simulators, systems able to provide objective measures of sensorimotor performance, are beginning to establish their utility in facilitating sensorimotor skill acquisition, and it is possible that they may also inform the prediction of clinical performance. Methods: A retrospective cohort study examined the relationship between student performance on a haptic VR simulator in the second year of undergraduate dental study with subsequent clinic performance involving patients 2 years later. The predictive ability was tested against a phantom-head crown test (a traditional preclinical dental assessment, in the third year of study). Results: VR scores averaged across the year explained 14% of variance in clinic performance, while the traditional test explained 5%. Students who scored highly on this averaged measure were ~10 times more likely to be high performers in the clinical crown test. Exploratory analysis indicated that single-trial VR scores did not correlate with real-world performance, but the relationship was statistically significant and strongest in the first half of the year and weakened over time. Conclusions: The data demonstrate the potential of a VR haptic simulator to predict clinical performance and open up the possibility of taking a data-driven approach to identifying individuals who could benefit from support in the early stages of training.

Frontal theta brain activity varies as a function of surgical experience and task error.

OBJECTIVE: Investigations into surgical expertise have almost exclusively focused on overt behavioral characteristics with little consideration of the underlying neural processes. Recent advances in neuroimaging technologies, for example, wireless, wearable scalp-recorded electroencephalography (EEG), allow an insight into the neural processes governing performance. We used scalp-recorded EEG to examine whether surgical expertise and task performance could be differentiated according to an oscillatory brain activity signal known as frontal theta-a putative biomarker for cognitive control processes. DESIGN SETTING AND PARTICIPANTS: Behavioral and EEG data were acquired from dental surgery trainees with 1 year (n=25) and 4 years of experience (n=20) while they performed low and high difficulty drilling tasks on a virtual reality surgical simulator. EEG power in the 4-7 Hz range in frontal electrodes (indexing frontal theta) was examined as a function of experience, task difficulty and error rate. RESULTS: Frontal theta power was greater for novices relative to experts (p=0.001), but did not vary according to task difficulty (p=0.15) and there was no Experience × Difficulty interaction (p=0.87). Brain-behavior correlations revealed a significant negative relationship between frontal theta and error in the experienced group for the difficult task (r=-0.594, p=0.0058), but no such relationship emerged for novices. CONCLUSION: We find frontal theta power differentiates between surgical experiences but correlates only with error rates for experienced surgeons while performing difficult tasks. These results provide a novel perspective on the relationship between expertise and surgical performance.

The factors that count in selecting future dentists: sensorimotor and soft skills.

Introduction Dental schools across the world are increasingly adopting 'multiple mini interview' (MMI) approaches to evaluate prospective students. But what skills and abilities are being assessed within these short, structured 'interview' stations and do they map on to the requirements of dental practice? Understanding the fundamental processes being measured is important if these assessments are to serve the purpose of identifying the students with the greatest potential to succeed in dental practice.Materials and methods To this end, we performed factor analysis on data from 239 participants on ten MMI stations used for undergraduate selection at a UK dental school.Results The analysis revealed that this assessment approach captured two fundamental underlying traits. The first factor captured scores on six stations that could be labelled usefully as a 'soft skill' factor. The second captured scores on four stations that could be described usefully as a 'sensorimotor' factor.Conclusion The present study demonstrates that the structure of at least one MMI used within the UK for dental school entry can be parsed into two distinct factors relating to soft skills and sensorimotor abilities. This finding has implications for the efficiency of the interview process, the refinement of MMI assessment in dental schools across the world and understanding of the critical skills that a successful dental practitioner must possess.

Drilling into the functional significance of stereopsis: the impact of stereoscopic information on surgical performance.

PURPOSE: One suggested advantage of human binocular vision is the facilitation of sophisticated motor control behaviours via stereopsis - but little empirical evidence exists to support this suggestion. We examined the functional significance of stereopsis by exploring whether stereopsis is used to perform a highly skilled real-world motor task essential for the occupational practice of dentistry. METHODS: We used a high fidelity virtual reality simulator to study how dentists' performance is affected by the removal of horizontal retinal image disparities under direct and indirect (mirror) observation. Thirteen qualified dentists performed a total of four different dental tasks under non-stereoscopic and stereoscopic vision conditions, with two levels of task complexity (direct and indirect observation) using a virtual reality dental simulator. RESULTS: Depth related errors were significantly higher under non-stereoscopic viewing but lateral errors did not differ between conditions. Indirect observation led to participants drilling less of the target area compared to direct viewing, but this did not interact with the stereopsis manipulation. CONCLUSIONS: The data confirm that dental practitioners use stereopsis and its presence results in improved dental performance. It remains to be determined whether individuals with stereo-deficits can compensate adequately. Nevertheless, these findings suggest an important role for stereopsis within at least one occupation and justify the design of simulators with 3D displays.

Cardiac electrophysiology of patients with spinal cord injury.

Spinal cord injury is a clinical syndrome encountered frequently in trauma centers and is accompanied by both acute and chronic heart rhythm abnormalities. The injury is characterized by sympathetic nervous system impairment with preservation of parasympathetic output via the vagus nerve. Severe bradycardia in the form of life-threatening sinus arrest or complete heart block may be observed in the acute recovery phase. Therapy for arrhythmias in the acute phase includes atropine, intravenous chronotropes, methylxanthines for the prevention of episodic bradycardia, and pacemaker implantation in severe cases. In the chronic recovery phase, autonomic dysreflexia in the form of paroxysmal hypertension is often induced by visceral organ distension or other stimuli and can be accompanied by bradycardia or tachycardia. The prognosis for survivors of spinal cord injury is expected to improve with further advances in surgical and medical care, and electrophysiologists will likely be called upon more frequently to help manage heart rhythm disorders in this setting.

Smooth muscle specific overexpression of p22phox potentiates carotid artery wall thickening in response to injury.

We hypothesized that transgenic mice overexpressing the p22(phox) subunit of the NADPH oxidase selectively in smooth muscle (Tg(p22smc)) would exhibit an exacerbated response to transluminal carotid injury compared to wild-type mice. To examine the role of reactive oxygen species (ROS) as a mediator of vascular injury, the injury response was quantified by measuring wall thickness (WT) and cross-sectional wall area (CSWA) of the injured and noninjured arteries in both Tg(p22smc) and wild-type animals at days 3, 7, and 14 after injury. Akt, p38 MAPK, and Src activation were evaluated at the same time points using Western blotting. WT and CSWA following injury were significantly greater in Tg(p22smc) mice at both 7 and 14 days after injury while noninjured contralateral carotids were similar between groups. Apocynin treatment attenuated the injury response in both groups and rendered the response similar between Tg(p22smc) mice and wild-type mice. Following injury, carotid arteries from Tg(p22smc) mice demonstrated elevated activation of Akt at day 3, while p38 MAPK and Src activation was elevated at day 7 compared to wild-type mice. Both increased activation and temporal regulation of these signaling pathways may contribute to enhanced vascular growth in response to injury in this transgenic model of elevated vascular ROS.

Can virtual reality trainers improve the compliance discrimination abilities of trainee surgeons?

The assessment of tissue compliance using a handheld tool is an important skill in medical areas such as laparoscopic and dental surgery. The increasing prevalence of virtual reality devices raises the question of whether we can exploit these systems to accelerate the training of compliance discrimination in trainee surgeons. We used a haptic feedback device and stylus to assess the abilities of naïve participants to detect compliance differences with and without knowledge of results (KR) (groups 1 and 2), as well as the abilities of participants who had undergone repetitive training over several days (group 3). Kinematic analyses were carried out to objectively measure the probing action. Untrained participants had poor detection thresholds (mean just noticeable difference, JND = 33%), and we found no effect of KR (provided after each trial) on performance (mean JND = 35%). Intensive training dramatically improved group performance (mean JND = 12%). Probing action (in particular, slower movement execution) was associated with better detection thresholds, but training did not lead to systematic changes in probing behaviour. These findings set a benchmark for training systems that act to increase perceptual sensitivity and guide the learner toward optimal movement strategies to improve discrimination.

Transitioning to the radial artery as the preferred access site for cardiac catheterization: an academic medical center experience.

OBJECTIVES: To evaluate procedural and safety metrics of transradial (TR) versus transfemoral (TF) cardiac catheterization (CATH) and percutaneous coronary interventions (PCI) during a complete institutional transition from TF to TR as the preferred access. BACKGROUND: The TR approach has been shown to reduce complications compared to TF for CATH and PCI, but concerns of longer procedure times have limited utilization in the United States. METHODS: 4,172 consecutive CATH and PCI procedures were performed (2,665 TF; 1,507 TR) at Wake Forest Baptist Medical Center from January 2009 to November 2010. We assessed in-hospital procedural and safety metrics. RESULTS: After 6 months of a preferred TR strategy, TR to TF crossover rate was 9.1%, and 65% of all cases were TR procedures. For the cath lab (all TF + TR), we observed small but significant increases in procedural metrics for Preferred TR (last third) compared to Preferred TF (first third). This appeared to be due to increased access times, procedure length, fluoroscopy times, and contrast use for TR versus TF (propensity score matched). Nonetheless, over the course of the study, there was a trend for a decrease in all procedural metrics with TR use. Access site complications (2.3% TF, 1.2% TR) and bleeding (2.5% TF, 2.1% TR), both P < 0.05, decreased over the course of the study. CONCLUSIONS: Our observations support the concept that complete transition of a cath lab to a preferred TR strategy is feasible, achieves lower rates of vascular and bleeding complications but with modest increases in overall procedural metrics.

Occlusal changes following posterior tooth loss in adults. Part 2. Clinical parameters associated with movement of teeth adjacent to the site of posterior tooth loss.

PURPOSE: Much anecdotal evidence is available on tooth positional changes following loss of an adjacent tooth, but only a few studies are available. In Part 1 of this series, supraeruption was assessed and Generalized Linear Models were made to determine the clinical parameters associated with the supraeruptive process. The models demonstrated that clinical parameters were not only associated with the extent of supraeruption, but also with the type of eruption present. This investigation of tooth positional changes adjacent to sites of posterior tooth loss attempts to provide increased understanding of the magnitude, direction, and associated features that may be helpful in decision making and treatment planning in the clinical setting. MATERIALS AND METHODS: One hundred patients with an unopposed posterior tooth, with 100 age, sex, and bone level matched controls, were drawn from patients undergoing routine restorative care at Leeds Dental Institute. Study models were scanned, and the extent of eruption, type of eruption of the unopposed tooth, the overbite, overjet, buccal occlusion, and degree of crowding in the dentition, tipping, rotation, and buccal movement of the teeth associated with the edentulous site were recorded. Generalized Linear Models were developed to examine associations between each tooth movement and patient or dental factors. RESULTS: A statistical significance in the degree of tipping of teeth both mesial and distal to the extraction site was detected between the subject and control groups. There was also a significant difference in rotation of the tooth mesial to the site. Four Generalized Linear Models were produced of the types of non-vertical movements found in teeth associated with sites of tooth loss. CONCLUSIONS: Teeth adjacent to the site of tooth loss may undergo non-vertical movements. Teeth mesial to the extraction site had a tendency to tip distally. The degree of tipping was increased in upper teeth and in subjects with a cusp-to-cusp buccal occlusion. Rotation of teeth mesial to the extraction site was more prevalent in the lower arch. Tipping of the tooth distal to the extraction site could be extreme and was found to be more prevalent in subjects with a reduced (Code 1) overbite and in the lower arch. Rotation of teeth distal to the extraction site was greater in the upper arch and was also associated with a reduced (Code 1) overbite. It also had an association with rotation of the tooth mesial to the extraction site. Models of non-vertical movement are likely to be of limited value due to overdispersion, indicating a high degree of variability within the model.

Occlusal changes following posterior tooth loss in adults. Part 1: a study of clinical parameters associated with the extent and type of supraeruption in unopposed posterior teeth.

PURPOSE: One of the barriers to restoring an edentulous space may be the supraeruption of an unopposed tooth to occupy some or all of the space needed for prosthetic replacement. The aim of this study was to determine the extent and type of supraeruption associated with unopposed posterior teeth and to investigate the relationship between these and oral and patient factors. MATERIALS AND METHODS: Diagnostic casts of 100 patients with an unopposed posterior tooth and of 100 control patients were scanned and analyzed to record the extent of supraeruption, together with other clinical parameters. The type of eruption present was defined for each subject as Periodontal Growth, Active Eruption, or Relative Wear. Generalized Linear Models were developed to examine associations between the extent and type of supraeruption and patient or dental factors. The extent of supraeruption for an individual was modeled to show association between the degree of supraeruption and clinical parameters. Three models were produced to show associations between each type of supraeruption and clinical parameters. RESULTS: The mean supraeruption for subjects was 1.68 mm (SD 0.79, range 0 to 3.99 mm) and for controls, 0.24 mm (SD 0.39, range 0 to 1.46 mm). The extent of supraeruption was statistically greater in maxillary unopposed teeth than in mandibular unopposed teeth. Supraeruption was found in 92% of subjects' unopposed teeth. CONCLUSIONS: A Generalized Linear Model could be produced to demonstrate that the clinical parameters associated with supraeruption are periodontal growth, attachment loss, and the lingual movement of the tooth distal to the extraction site. Three types of supraeruption, which may be present singly, or in combination, can be identified. Active eruption has an association with attachment loss. Periodontal growth has an inverse association with attachment loss, is more prevalent in younger patients, in the maxilla, in premolars, and in females. Relative wear has an association with increasing age and is more prevalent in unopposed mandibular teeth.

2.1 Evolving methods of assessment.

This Working Section is concerned with evolving methods of assessment in dental education. It focuses on newer methods of assessment that might have relevance for broader application. Although it cannot provide answers to all the questions it raises, it is hoped that the contribution it makes is of value in the process of the development of a global network in dental education.

AMEE Medical Education Guide No. 22: Refreshing lecturing: a guide for lecturers.

This guide provides an overview of research on lecturing, a model of the processes of lecturing and suggestions for improving lecturing, learning from lectures and ways of evaluating lectures. Whilst primarily directed at teachers in the healthcare professions, it is equally applicable to all teachers in higher education. Lectures are the most ubiquitous method of teaching so they are an important part of a teacher's repertoire. Lectures are at least as effective as other methods of teaching at imparting information and explaining. Intention, transmission and output are the basis of a model of lecturing. The key skills of preparing lectures, explaining and varying student activities may be derived from the model. Preparation is based on purposes, content, various structures of lectures and the preparation of audiovisual aids. The essential ingredients of explaining are clarity, interest and persuasion. By varying activities, one can renew attention and develop student learning. Learning from lectures can be improved by teaching students the structure of lectures and methods of listening and note-taking. Student ratings of lectures are useful but over-used and limited ways of evaluating lectures. Equally important is peer review and more important than either student ratings or peer feedback is reflection on the practice of lecturing by individuals and course teams.