This study was to determine the effectiveness of diode laser (LI) and ultrasonic (UI)‐activated irrigation with or without a surfactant as adjunct techniques during the retreatment of gutta‐percha and tricalcium silicate‐based sealer (BC) sealer. Forty‐two single‐rooted premolars were instrumented and filled with gutta‐percha and BC sealer, then retreated using NiTi retreatment rotary files. Teeth were randomly divided into three equal groups: Control (manual irrigation), UI and LI groups. Each group was subdivided into 2.5% NaOCl irrigant and ChlorCid™️ Surf subgroups. The amount of material removed following UI and LI was significantly greater than that of manual irrigation (p < 0.0001). However, there was no significant difference between the surfactant subgroups, irrespective of irrigation technique (p = 1.00, p = 0.535, p = 0.805). The use of UI and LI adjuncts to NiTi rotary retreatment techniques showed significant improvement in gutta‐percha with BC sealer removal. However, surfactants had no effect on the efficacy.

Objective: This study aimed to evaluate the knowledge and perception of dental students and interns about Light-Curing Units (LCUs), at Princess Nourah Bint Abdulrahman University (PNU), Riyadh, KSA. Materials and Methods: The online questionnaire entailed 14 questions that were grouped under three sections: (1) Demographics, (2) LCUs and light-activated materials and (3) LCUs' maintenance, safety and disinfection. Chi-Square and ANOVA tests were used to compare the groups with a significance fixed at p ≤0.05.Results: A total of 108 dental students and interns participated in the survey.Regarding the overall knowledge among the groups, an insignificant statistical difference was found between the groups' knowledge of LCUs based on the level of education (P-value=0.231). As for the appropriate infection control methods, many have answered correctly (69.4%). Regarding the use of radiometers (50.9%) of the participants do not use radiometers in their daily practice, moreover (36.1%) were not familiar with the device. Conclusion:Our findings suggest that dental students and interns have very low overall knowledge regarding the light-curing units while demonstrating relatively high awareness toward maintenance and infection control protocols.