Optimizing fracture resistance of endodontically treated maxillary premolars restored with preheated thermos-viscous composite post-thermocycling, a comparative study. Part I.

PURPOSE: This research aimed to investigate fracture resistance of endodontically treated maxillary premolars restored using preheated thermo-viscous and fiber-reinforced bulk fill resin composite, in vitro. METHODOLOGY: Sixty sound human maxillary premolars were selected and divided randomly into 6 groups of ten teeth each (n = 10). Group 1; is the positive control with sound unprepared teeth (P), Group 2; is the negative control in which Mesio-occluso-distal (MOD) cavities were left unrestored (N), Group 3; includes the teeth restored by incremental packing with conventional nanohybrid composite (ChP), Group 4; includes teeth restored with short fiber reinforced bulk fill composite (EF), Group 5; includes teeth restored with preheated thermo-viscous bulk fill composite (VB), and Group 6; includes teeth restored using packable bulk fill composite (XF) Tested restorative materials were bonded with a universal adhesive in self-etch mode. Teeth were kept in distilled water for 24 h at 37 °C proceeded by thermocycling (5- 55 °C, 1200×). Teeth were then exposed to compressive load till fracture at a crosshead speed of 1 mm/min. One-way ANOVA followed by Tukey post-hoc test was implemented to compare between more than two groups in non-related samples. The significance level was established at α = 0.05 for both tests. RESULTS: Intact teeth significantly recorded the highest fracture resistance values among all groups. A significant difference was recorded among all the tested groups, with the EF recording the highest values, followed by the VB group then the XF group and ChP that recorded the lowest data. Negative control premolars significantly recorded the lowest fracture. CONCLUSIONS: After thermocycling, endodontically treated maxillary premolars restored with pre-heated thermos-viscous composite did not exhibit an increase in fracture resistance. Notably, our findings indicate that short fiber-reinforced composite demonstrated significantly higher fracture resistance compared to other types of composites assessed in this study. This suggests the potential superiority of short fiber-reinforced composite in enhancing the overall structural integrity of endodontically treated teeth subjected to occlusal forces.

Evaluation of the Dunning-Kruger Effects among Dental Students at an Academic Training Institution in UAE.

Background: The Dunning-Kruger effect (cognitive bias) is a psychological phenomenon that implies that individuals with a lack of knowledge and skills have an unrealistically optimistic image of their abilities compared to others. Purpose: The study aimed to examine the presence of the Dunning-Kruger effect in fifth (final) year dental undergraduate students at Gulf Medical University, UAE, in clinical domains related to pediatric dentistry. Methods: A longitudinal cohort study was conducted at Gulf Medical University, College of Dentistry, to evaluate cognitive bias among 5th-year dental students at GMU in the competency domains of communication, diagnosis, and clinical skills in Pediatric dentistry. Results: Overall, compared to the level of confidence of students in September, there was a decline in the level of confidence in January. With an increase in time, the percentage shifted to a higher level in May across all domains. Conclusion: Characteristic patterns of fluctuations in students' self-confidence during clinical exposure are observed. The research results prove that the Dunning-Kruger effect, the cognitive bias of the perception pattern, is present in the examined group of dental students.