Three-dimensional filling of root canals is important for the success of endodontic treatment. The complexity and differences in root canal anatomy in C-shaped canals lead to difficulties in endodontic procedures and make it difficult to compare root canal filling techniques reliably. This study aimed to evaluate the percentage of gap areas of different root canal filling techniques in 3D-printed C2 and C3-shaped root canals using micro-computed tomography (micro-CT). Root canals of two human mandibular molars in C2 and C3 configurations were prepared and scanned with micro-CT. Forty replicas (80 in total) were produced from each configuration using a 3-dimensional (3D) printer. C2 and C3 groups were divided into 4 groups according to filling techniques (n = 10); core carrier (CC), cold lateral compaction (CLC), continuous wave obturation (CW) and single cone technique with calcium silicate-based sealer (SC-CSS). Root canals were filled and scanned with micro-CT. The gap areas in the apical, middle and coronal thirds were calculated as percentages. The one-way ANOVA test was used to evaluate the percentages of gap areas and Tukey’s test for multiple comparisons. In C2-shaped canals, SC-CSS group showed a statistically higher percentage of gap areas in the apical third (p <.05), there were no significant differences among other groups (p >.05). In the middle part, there were no significant differences among groups (p >.05). The CW group showed a significantly lower percentage of gap areas in the coronal third than other groups (p <.05). In C3-shaped canals, SC-CSS group showed statistically higher percentage of gap areas in apical third (p <.05), CC and SC-CSS groups showed lower percentage areas in the middle part compared to CLC and CW groups (p <.05) and there was no difference between among groups in the coronal third (p >.05). The SC-CSS technique showed more gap areas in the apical region of C2 and C3-shaped canals. Considering any root canal filling technique in clinical practice, the compaction of filling material in the large volume canals of the C-shaped root canal system is necessary to reduce gap areas.

Objectives: The aim of this in vitro study was to evaluate the fracture resistance of endodontically treated upper premolar teeth restored with different resin composites. Materials and Methods: Hundred and eight maxillary premolar teeth were randomly divided into nine groups (n=12). The teeth in the first group were left intact and tested as unprepared group 1 (negative control) (group 1). Other eight groups were prepared with MOD cavities and endodontically treated. The teeth in group 2 (positive control) were unrestored. Other groups were restored with different resin composites. Group 3: conventional resin composite and group 4-9 six bulk fill resin composite (group 4: 3M Filtek Flowable Bulk Fill, group 5: 3M Filtek Posterior Bulk Fill, group 6: Voco X-tra base, group 7: Voco X-tra fil, group 8: Dentsply SDR Flow, group 9: Dentsply Quixfil). Single Bond Universal was applied as self-etch, according to application instructions. The restored teeth were stored in distilled water for 24 hours at 37°C. Compressive force was applied parallel to the long axis of the teeth. The test was carried out at a speed of 1mm/min. ANOVA and Tukey HSD tests were used in the analysis of the data (p,0.05). Results: Conventional resin composite (group 3) showed lower fracture resistance than bulk fill resin composites (p<0.05) . There was no significant difference between the groups restored with bulk fill composites (p≥0.05). Conclusions: The bulk fill composites increase the fracture resistance of endodontic treated teeth,

This in vitro study assessed tooth color and whiteness changes following application of a commercial LED-assisted over-the-counter (OTC) whitening system, and characterized subsequent color changes under different immersion conditions. Sixty extracted human maxillary incisors were whitened once daily for 15 consecutive days in ten six-tooth acrylic arch models. After whitening, the models were randomly allocated to five immersion conditions (two models; n = 12 teeth per condition): distilled water, black tea, coffee, cola, and red wine. Specimens were immersed in the assigned medium for 4 h daily for 15 days using a single shared container per group. Tooth color was measured with a spectrophotometer at baseline (T0), after whitening (T1), and after staining (T2). Color change was assessed using CIEDE2000 (ΔE00), the Whiteness Index for Dentistry (WI_D), and supportive ΔEab values. Mean WI_D increased from 15.66 ± 5.14 at T0 to 26.23 ± 5.67 at T1 (p < 0.001), with a mean ΔWI_D of 10.58 ± 1.97 and ΔE00 of 5.00 ± 0.87. All specimens exceeded the 50:50 acceptability thresholds for both outcomes. Descriptive post-whitening color changes varied across immersion conditions, including distilled water; however, the absence of independent container-level replication precluded valid inferential comparisons between staining media. Red wine showed the highest mean ΔE00 (16.13 ± 3.42), whereas cola showed the largest numerical loss of whiteness. The complete commercial whitening system was associated with a measurable increase in dental whiteness, whereas subsequent color changes represented descriptive laboratory observations rather than independently confirmed beverage effects.

Objective: This randomized, single‐blind clinical trial evaluated the effect of whitening dentifrices on short‐term color stability and tooth sensitivity after in‐office bleaching. Materials and Methods: A total of 120 participants treated with 40% hydrogen peroxide were randomly assigned to six dentifrice groups ( n = 20): one conventional dentifrice (control) and five whitening dentifrices with different mechanisms (abrasive, optical, and chemical). One whitening formulation also contained potassium nitrate as a desensitizing agent. Tooth color was measured spectrophotometrically at baseline, immediately after bleaching, and at 1 week, 1 month, and 3 months using the CIELAB system (ΔE*ab). Tooth sensitivity was recorded using a numeric rating scale at 24 h, 48 h, and 7 days. Color change data were analyzed using repeated‐measures ANOVA with Greenhouse–Geisser correction, whereas tooth sensitivity data were analyzed using Friedman, Wilcoxon signed‐rank, and Kruskal–Wallis tests with Bonferroni adjustment ( α = 0.05). Results: No significant differences in color change were observed among groups at any evaluation time point ( p > 0.05). A significant time × group interaction was detected ( p < 0.05), mainly due to a reduction in ΔE*ab values in the control group at 3 months, whereas whitening dentifrices did not show significant intragroup changes over time. No significant differences were found among whitening dentifrices. Tooth sensitivity peaked within the first 48 h and decreased over time, approaching zero by Day 7. The dentifrice containing desensitizing agents exhibited significantly lower sensitivity scores during the early postbleaching period ( p < 0.05). Conclusions: No statistically significant differences in color change were observed among dentifrice groups at individual time points; however, differences in color change patterns over time were identified. These findings reflect differences in intragroup trends rather than direct intergroup superiority. Tooth sensitivity was transient and resolved within 1 week in all groups, with lower early sensitivity scores observed in the formulation containing desensitizing agents.