Introduction: Erosion is an important cause of tooth mineral loss. The combined use of lasers and fluoride has been introduced as a novel modality for the prevention of enamel demineralization. This study aimed to assess the effect of Er:YAG laser combined with fluoride application on primary and permanent enamel resistance to erosion. Methods: Eighty enamel specimens of permanent (n=40) and primary (n=40) molars were prepared and randomly assigned to 4 groups: C-control (no pretreatment), F-acidulated phosphate fluoride (APF) gel, FL-APF gel application followed by Er:YAG laser irradiation, and LF-Er:YAG laser irradiation followed by the application of APF gel . The specimens were then submitted to pH cycling using Coca-Cola (pH = 2.4). Enamel micro-hardness was measured using the Vickers microhardness tester before pretreatment and after the erosive process. The collected data were analyzed using the Kolmogorov-Smirnov test, two-way ANOVA and repeated measures ANOVA. Results: The micro-hardness of both permanent and primary enamel specimens significantly decreased after the erosive process (P < 0.05). In the permanent enamel specimens, the greatest reduction in micro-hardness was noted in groups C and F, while the least reduction was noted in group FL. However, these differences were not statistically significant (P > 0.05). In the primary enamel specimens, the greatest reduction in micro-hardness was noted in groups C and LF, while the least reduction was noted in group F. These differences were not statistically significant (P > 0.05). Conclusion: Within the limitations of this study, Er:YAG laser irradiation combined with fluoride application could not prevent erosion in permanent and primary enamel during the erosive process.

Compassion fatigue is a common complication in nurses, which can lead to burnout, job dissatisfaction, and a decline in the quality of patient care. This study aimed to investigate the impact of loving-kindness meditation on compassion fatigue of nurses working in the neonatal intensive care unit (NICU). This cluster-blinded randomized clinical trial study was conducted on 66 NICU nurses in 2 educational hospitals selected. The intervention group received a 1-month online program for daily training and practice of loving-kindness meditation. The control group received miscellaneous files on mental health during the COVID-19 pandemic period. The Nursing Compassion Fatigue Inventory (NCFI) was filled out by the 2 groups, before and after the intervention. The results showed that the mean scores of the NCFI in the intervention group decreased significantly compared with before the intervention (P = .002). In comparison with the control group, there was a significant difference between the mean scores of the 2 groups after the intervention (P = .034). Among nurses working in NICU, loving-kindness meditation significantly reduces compassion fatigue after 1 month. These findings support the use of this intervention for nurses.