Marili Doro Deonizio

Influence of apical patency and cleaning of the apical foramen on periapical extrusion in retreatment.

This study evaluated the influence of apical patency, root filling removal technique and cleaning of the apical foramen, concerning the amount of debris extruded during root canal retreatment. Forty mandibular incisors were randomly assigned to 4 groups - GIM (n=10), GIIM (n=10), GIPT (n=10) and GIIPT (n=10), which were named according to leaving (I) or not (II) apical patency during canal preparation and filling removal technique (manual - M or ProTaper system - PT). After filling material removal, each specimen of each group had the apical foramen cleaned by sizes 15, 20 and 25 instruments, generating 12 subgroups: GIM15, GIM20, GIM25, GIIM15, GIIM20, GIIM25, GIPT15, GIPT20, GIPT25, GIIPT15, GIIPT20 and GIIPT25. Extruded filling debris was collected by a Milipore filtration system, an HV-durapore, 0.45 µm pore filter with a 25 mm diameter. The filters were weighed before and after the collection on an analytical scale (10-5 g), and the difference was calculated. The mean weight of extruded filling debris was analyzed statistically by Kruskal-Wallis and Friedman ANOVA tests (α=0.05). The mean values found in the groups (in mg) were: GIM (0.95 ± 0.94), GIIM (0.47 ± 0.62), GIPT (0.30 ± 0.31) and GIIPT (0.32 ± 0.44). There was no statistically significant difference among any of the groups or subgroups (p>0.05). ProTaper provided the smallest amount of extruded filling material, regardless of presence or absence of apical patency, followed by manual technique, without and with apical patency. Additional amounts of debris were collected during cleaning of the apical foramen, regardless of the instrument, presence/absence of patency or root filling removal technique.

Effectiveness of different obturation techniques in surpassing the ledge formed in simulated curved canals

Aim: To compare the effectiveness of different obturation techniques in surpassing the ledge formed in simulated curved root canals. Methods: Eighty acrylic-resin blocks with curved canals were instrumented with Gates-Glidden drills to simulate a ledge formation. Then, a K-File #10 was used for trying to surpass the deviation, and the blocks that permitted surpassing were rejected. The remaining blocks were divided into 4 groups according to the obturation technique: lateral condensation, Tagger’s Hybrid technique, Thermafil and System B. The blocks had their images digitalized using a scanner before and after the obturation procedures. The images were analyzed with Image Tool 3.0 software. Statistical analysis was performed by one-way ANOVA at a significant level of 5%. Results: The System B resulted in the highest obturated area (p 0.05). The lateral condensation resulted in the worst ability in filling the ledge space (p<0.001). Conclusions: Within the limitations of this study, it was possible to conclude that techniques using heat condensation or gutta-percha thermoplastification were more effective in surpassing the ledge formed in curved canals than the lateral condensation.