Towards quantitative analysis of enamel erosion by focused ion beam tomography.

OBJECTIVES: The purpose of this work is a proof of concept to introduce a new quantitative 3D-analysis of dental erosion obtained by focused ion beam (FIB) tomography associated with silver nitrate penetration into porosities in etched enamel. METHODS: One sample selected was sound enamel after removal of the aprismatic surface. The other was studied after applying an additional attack with orthophosphoric acid. Both surfaces were infiltrated with silver nitrate via immersion. After dehydration, samples were observed in a dual column FIB/SEM station. Serial FIB sectioning was conducted with a current of 3nA at 30keV and an increment step of 20nm for the healthy enamel and of 40nm for the etched one. 3D analysis was performed with Fiji software and BoneJ plugin and several parameters were obtained to characterize the tissue: non-mineralized phase content (NMP), connected porosity fraction (CPF) and degree of anisotropy (DA) of the NMP. RESULTS: Healthy enamel showed an NMP content of 0.5vol.%, with a bimodal distribution of non-mineralized regions, inside the prisms and between the prisms. No silver penetration was noticed in the healthy enamel, demonstrating the absence of open porosity. In contrast, silver nitrate penetration after acidic exposure was observed, up to a depth of 12µm, which allowed the calculation of an interconnected porosity volume fraction (CPF) of 3.1vol.%, mostly between the prisms. Values for DA of 0.56 for sound enamel and 0.81 for acid-etched surface were determined, highlighting a higher degree of anisotropy in the latter. SIGNIFICANCE: Quantitative analysis of FIB tomography using NMP, CPF and DA should contribute to a better understanding and follow up of dental erosion, correlation between erosion and attrition or abrasion process, and the ability to develop enamel remineralization procedures.

Effect of a Person-Centered Course on the Empathic Ability of Dental Students.

Person-centered or patient-centered care (PCC) focuses on the individual's needs and concerns. Although PCC is widely acknowledged as a core value of modern medicine, there has been a lack of research on how dental curricula could engage future dentists in PCC approaches. The aim of this study was to assess the impact of a PCC course on empathy in dental students. A controlled study was conducted with fourth-year dental students in four dental faculties in France in 2014-15. The test group (n=63) received 20 hours of PCC training including arts-based approaches, narrative dentistry activities, and workshops on communication based on the Calgary-Cambridge guide. There was no change in the curriculum of the control group (n=217). Pretest and posttest measures with the Toronto Empathy Questionnaire (TEQ) and Jefferson Scale of Physician Empathy (JSPE) were compared for the two groups. The comparisons showed no significant differences on the TEQ or JSPE (p=0.25 and p=0.08, respectively). However, there was a higher proportion of students with more than an eight-point decrease in TEQ values in the control group (p=0.02). The stabilization of empathic ability in the test group may have counteracted the tendency for natural erosion of empathy among students during their clinical activities. These results suggest that PCC training constitutes a promising approach to developing dental students' empathic ability, but there is a need to assess the effects of such training over longer periods.