Histological analysis of cleaning capacity in apical third of flattened root canals with passive ultrasonic irrigation

Introduction and Objective: The aim of this study was to evaluate histologically the passive use of ultrasound for cleaning the apical portion of flattened root canal systems. Material and methods: The sample consisted of 20 extracted human mandibular incisors which were divided into two groups after being prepared with the rotary system Hero 642 up to size #45 surgical diameter: Group A - final irrigation with 4 ml of 2.5% sodium hypochlorite by the conventional technique using a syringe, and Group B - final irrigation with 4 ml of 2.5%, sodium hypochlorite divided into 1 ml amounts which were activated with the passive use of ultrasound for 15 seconds each time, generating a total activation period of 1 minute. Following, the teeth were subjected to morphometric analysis to evaluate the cleaning ability promoted in both groups. Results and Conclusion: Statistical analysis showed significant difference (p < 0.05) between the groups, with the passive ultrasonic irrigation resulting in cleaner canals.

Fracture susceptibility of endodontically treated teeth.

AIM: To assess the influence of cervical preparation on fracture susceptibility of roots. MATERIAL AND METHODS: During root canal instrumentation, the cervical portions were prepared with different taper instruments: I: no cervical preparation; II: #30/.08; III: #30/.10; IV: #70/.12. The specimens were sealed with the following filling materials (n = 8), A: unfilled; B: Endofill/gutta-percha; C: AH Plus/gutta-percha; D: Epiphany SE/Resilon. For the fracture resistance test, a universal testing machine was used at 1 mm per minute. RESULTS: anova demonstrated difference (P < 0.05) between taper instruments with a higher value for group I (205.3 ± 77.5 N) followed by II (185.2 ± 70.8 N), III (164.8 ± 48.9 N), and IV (156.7 ± 41.4 N). There was no difference (P > 0.05) between filling materials A (189.1 ± 66.3 N), B (186.3 ± 61.0 N), C (159.7 ± 69.9 N), and D (176.9 ± 55.2 N). CONCLUSIONS: Greater cervical wear using a #70/.12 file increased the root fracture susceptibility, and the tested filling materials were not able to restore resistance.