This study aimed to evaluate the effect of direct restorations using unidirectional glass fiber orientations and a short-fiber-reinforced composite (SFRC) on the fracture resistance of endodontically treated premolars with mesio-occluso-distal cavities. Ninety double-rooted premolars were selected. Fifteen teeth were left intact/as a control group. The endodontic treatment and cavity preparations of seventy-five teeth were performed and divided into five experimental groups: Resin composite (RC), modified transfixed technique + RC, circumferential technique + RC, cavity floor technique + RC, and SFRC + RC. All teeth were fractured under oblique static loading at a 30° angle using a universal testing machine. The fracture patterns were observed and classified. Data were analyzed with one-way analysis of variance, Pearson chi-square, and Tukey HSD post hoc tests (p = 0.05). The highest fracture strength values were obtained in intact teeth (599.336 N), followed by modified transfixed + RC treated teeth (496.58 N), SFRC + RC treated teeth (469.62 N), RC (443.51 N), circumferential + RC treated teeth (442.835 N), and cavity floor + RC treated teeth (404.623 N) (p < 0.05). There was no significant difference between the RC and the circumferential technique + RC (p > 0.05). Unrepairable fractures were observed at low rates (20%) in the modified transfixed + RC and SFRC + RC teeth, and at higher rates in RC (73.3%), cavity floor + RC (60%), and circumferential + RC (80%) teeth. The application of an SFRC or the modified transfixed technique yielded an improved fracture strength and the fracture pattern of ETPs being restored with a universal injectable composite.

This study assessed the effects of sequential and continuous chelation using phytic acid and etidronic acid on smear layer removal, microhardness, and push-out bond strength (PBS) at radicular dentin. One hundred twenty single-rooted teeth were selected. Thirty teeth were split longitudinally, and initial microhardness was measured. The roots were then divided into six groups. In sequential chelation, 2.5% sodium hypochlorite (NaOCl) was used for 20 min, followed by 17% ethylenediaminetetraacetic acid (EDTA), 9% etidronic acid (HEDP), or 2.5% phytic acid (PA) for 2 min, while no chelator was applied in the control group. In continuous chelation, etidronic acid (DR HEDP) or phytic acid (DR PA) was mixed with NaOCl and applied for 20 min. Final microhardness values were measured, and the change was calculated as a percentage. Mid-root sections were obtained from the 60 teeth for the PBS test and divided into six groups. Irrigants were applied as in the microhardness test. Sections obturated with calcium silicate cement. PBS values were measured, and the types of failures were analyzed. Thirty teeth were analyzed using scanning electron microscopy (SEM). In sequential chelation, 2.5% NaOCl irrigation was performed during instrumentation, followed by 17% EDTA, 9% HEDP, or 2.5% PA for 2 min, while no chelator was applied in the control group. In continuous chelation, DR HEDP or DR PA was mixed with NaOCl and used during instrumentation. Images were taken, and smear layer scores were recorded. The PBS data were analyzed using one-way ANOVA, and the alterations in microhardness and remaining smear layer were analyzed using a two-way ANOVA test. The pairwise comparisons were analyzed using Tukey’s HSD post hoc test. The failure patterns and smear scores were compared using Pearson’s chi-squared test (α = 0.05). Results showed that DR HEDP (4.02 ± 0.68%) caused the least reduction in microhardness. DR HEDP (10.26 ± 1.74 MPa) exhibited the highest bond strength, followed by PA (7.97 ± 0.92 MPa) and DR PA (7.74 ± 1.16 MPa). Failure patterns did not differ significantly. Lower percentages of the remaining smear layer area were observed in the DR PA (26.7 ± 18%), PA (24.2 ± 9.8%), and DR HEDP (37.1 ± 16.5%) groups compared to the others. The use of etidronic acid with the continuous chelation technique and phytic acid with the sequential chelation technique may be an alternative method to sequential EDTA irrigation.

The aim of this study was to evaluate the whitening and abrasion effects of dentifrices containing different whitening agents on artificially stained and unstained enamel. 160 human dental enamel discs were distributed into four groups according to the type of dentifrices applied on them (n=40): Group I, non-whitening dentifrice (control group); Group II, dentifrice containing charcoal; Group III, dentifrice containing blue covarine; Group IV, dentifrice containing hydrogen peroxide. Half of the specimens in each group were immersed in coffee solution. Color measurements were evaluated from stained and unstained specimens before and after brushing by a spectrophotometer. The surface roughness of each unstained specimen was analyzed using a profilometer after the brushing and bleaching. The surface of one randomly selected specimen from each group was observed using a scanning electron microscope (SEM). Statistical analysis of the color change was performed using the Kruskal-Wallis test. The one-way ANOVA was used to evaluate surface roughness. Group III provided significantly higher recovery on ∆E00 values than other groups on the unstained enamel (p<0.05). Group IV showed significantly the highest ∆E00 values on stained enamel (p<0.05) and also Group IV showed the highest surface roughness values (p<0.05), SEM revealed a more irregular surface in groups III and IV. It can be stated that dentifrice containing blue covarine is both an effective and a safe way to provide whiter teeth with routine home tooth brushing.

Objectives: The aim of this study was to compare conventional needle irrigation (CNI), passive ultrasonic irrigation (PUI), and XP-endo Finisher (XPF) techniques in terms of modified triple antibiotic paste (mTAP) removal.Materials and Methods: A total of 30 mandibular premolars were instrumented to a size F3 file. A mixture of mTAP was prepared by mixing 3 antibiotics, including 250 mg ciprofloxacin, 250 mg metronidazole, and 150 mg clindamycin, with 1 ml distilled water and applied into the root canals. The teeth were allocated into 3 equal groups, irrigation/agitation was performed and teeth were divided into two halves. The removal of mTAP was evaluated with a scanning electron microscope by using the 4 grade scoring system.Results: In the apical thirds, significant difference was found between PUI and CNI groups (p 0.05). No statistically significant difference was found between all groups in the middle third. In the coronal thirds, XPF removed significantly more mTAP than the CNI group (p0.05). Conclusions: Passive ultrasonic irrigation and XPF file agitation demonstrated superior efficacy in removing mTAP from root canals compared to CNI.