Color Regression and Maintenance Effect of Intracoronal Whitening on the Quality of Life: RCT-A One-year Follow-up Study.

OBJECTIVE:: This randomized clinical study evaluated two parameters: 1) the clinical color rebound of whitening patients' tooth discoloration using the walking bleaching technique and 2) the impact on psychological and aesthetic self-perception at the one-year follow-up of patients who underwent bleaching of nonvital teeth. METHODS AND MATERIALS:: Fifty study participants with nonvital tooth discoloration were recruited. Teeth were assigned randomly into one of two groups: 1) 35% hydrogen peroxide (n=25) and 2) 37% carbamide peroxide (n=25). Intracoronal bleaching was carried out over the course of four sessions using the walking bleach technique. Tooth color was evaluated after each session in order to measure the total color variation (ΔE). The guide was arranged from highest (B1) to lowest values (C4) for evaluating color, and color changes using Vita Classical Shade (ΔSGUs) units were calculated. Subjective and objective assessments were compared with the counterpart of the tooth. Aesthetic perception and psychosocial factors were evaluated before and after treatment by the Oral Health Impact Profile (OHIP) and Psychological Impact of Dental Impact Questionnaire (PIDAQ) surveys. RESULTS:: Color changes (ΔE) were 15.48 ± 5.17 and 14.02 ± 4.85 for carbamide and hydrogen peroxide groups, respectively. There were no significant differences ( p>0.05) between these two groups at the one-year follow-up. There was a decrease in the PIDAQ scores after treatment compared to baseline values ( p<0.05). The majority of OHIP values regressed to baseline values. CONCLUSION:: The technique of walking bleaching was highly effective and showed minimal color rebound in nonvital teeth and had a positive effect on patients' psychological impact at the one-year follow-up.

Encouraging intrinsic motivation in the clinical setting: teachers' perspectives from the self-determination theory.

INTRODUCTION: Self-determination theory postulates that the three basic psychological needs of autonomy, competence and relatedness have to be satisfied for students to achieve intrinsic motivation and internalisation of autonomous self-regulation towards academic activities. Consequently, the influence of the clinical teaching environment becomes crucial when satisfying these needs, particularly when promoting or diminishing students' intrinsic motivation. The aim of this study was to describe and understand how clinical teachers encourage intrinsic motivation in undergraduate dental students based on the three basic psychological needs described by the self-determination theory. METHODS: A qualitative case study approach was adopted, and data were collected through semistructured interviews with nine experienced undergraduate clinical teachers of one dental school in Santiago, Chile. Interview transcripts were analysed by two independent reviewers using a general inductive approach. FINDINGS: Several themes emerged outlining teaching strategies and behaviours. These themes included the control of external motivators; gradual transference of responsibility; identification and encouragement of personal interests; timely and constructive feedback; delivery of a vicarious learning experience; teamwork, team discussion, and presence of a safe environment, amongst others. Overall, teachers stressed the relevance of empowering, supporting and building a horizontal relationship with students. CONCLUSIONS: Our findings regarding dental education expand on the research outcomes from other health professions about how teachers may support students to internalise behaviours. An autonomy-supportive environment may lead students to value and engage in academic activities and eventually foster the use of an autonomy-supportive style to motivate their patients.

Bi-directional electrical characterisation of microbial fuel cell.

The electrical performance of microbial fuel cells in steady-state is usually investigated by standard characterisation methods that reveal many important parameters e.g. maximum power. This paper introduces a novel "bi-directional" method to study how the acquisition parameters (i.e. sweep rate and sweep regime) can influence measurements and consequently performance estimations. The investigation exhibited considerable differences (hysteresis) between the forward and backward characterisation regimes, indicating a difficulty to reach steady-state under certain conditions. Moreover, it is found that fast sweep rates (time-step of 2 min) can lead to an overestimation of the short-circuit currents, while prolonged operation with high external loads leads to maximum power overestimation and extended conditioning at high currents can result in its underestimation.