Evaluation of bond strength of various epoxy resin based sealers in oval shaped root canals.

BACKGROUND: The aim of this study was to evaluate the bond strength of AH plus, Acroseal, and Adseal to the root canal dentin. METHODS: A total of 36 single-rooted, mandibular premolar teeth were used. Root canal shaping procedures were performed with ProTaper rotary instruments (Dentsply Maillefer) up to size F4. The prepared samples were then randomly assembled into 3 groups (n = 12). For each group, an ultrasonic tip (size 15, 0.02 taper) which was also coated with an epoxy resin based sealer and placed 2 mm shorter than the working length. The sealer was then activated for 10 s. A push-out test was used to measure the bond strength between the root canal dentine and the sealer. Kruskal-Wallis test to evaluate the push-out bond strength of epoxy based sealer (P = 0.05). The failure mode data were statistically analyzed using Pearson's chi square test (P = 0.05). RESULTS: Kruskal-Wallis test indicated that there were no statistically significant difference among the push out bond strength values of 3 mm (p = 0.123) and 6 mm (P = 0.057) for groups, there was statistically significant difference push out bond strength value of 9 mm (P = 0.032). Pearson's chi square test showed statistically significant differences for the failure types among the groups. CONCLUSION: Various epoxy resin based sealers activated ultrasonically showed similar bond strength in oval shaped root canals. Apical sections for all groups have higher push out bond strength values than middle and coronal sections.

Effectiveness of different irrigation procedures for removal of dentin debris from a simulated internal resorption cavity.

PURPOSE: The aim of this study was to compare the efficiency of different final irrigation techniques to remove artificially placed dentinal debris from a simulated internal root resorption (IRR) cavity. METHODS: Seventy teeth were prepared using the ProTaper system. The roots were then split longitudinally into two halves, in each of which standardized IRR cavities were prepared. Five teeth were set aside to serve as negative control group. Each cavity of the remaining 65 teeth was filled with dentin debris mixed with 2.5% NaOCl. Another 5 teeth (positive control) were not subjected to the debris removal procedure. Sixty teeth were randomly divided into four experimental groups (n = 15), according to the final irrigation technique used: conventional syringe irrigation (CSI), the Self-Adjusting File (SAF), passive ultrasonic irrigation (PUI), and the EndoActivator (EA). Ten milliliters of 2.5% NaOCl was used during the debris removal procedure. The root halves were disassembled, and the amount of remaining debris was evaluated under a stereomicroscope at 30× magnification. RESULTS: SAF and PUI removed debris significantly better than CSI and EA (P<.05). CSI was the least effective in debris removal (p<0.05). CONCLUSIONS: None of the irrigation techniques used was able to completely remove debris from simulated IRR cavities.

Bond strength of calcium silicate-based sealers to dentine dried with different techniques.

OBJECTIVE: To assess the influence of various canal-drying techniques on the push-out bond strength between radicular dentine and both MTA Fillapex and iRoot SP sealers. MATERIALS AND METHODS: Eighty extracted single-root teeth were instrumented with ProTaper Universal rotary instruments to a size F4. The teeth were randomly assigned to 1 of 4 groups as follows: group 1, excess fluid in the canals was removed using a Luer vacuum adapter; group 2, the canals were dried with a single paper point; group 3, the canals were dried with 3-5 paper points, and group 4, the canals were rinsed with 95% ethanol and then dried with 3-5 paper points. In each group, the specimens were subgrouped according to root canal sealer into either subgroup A (MTA Fillapex) or subgroup B (iRoot SP sealer). Horizontal sections (thickness 1 ± 0.1 mm) were obtained from each specimen and a push-out test was performed using a universal testing machine at a crosshead speed of 1 mm/min on root slices. Statistical analysis was done using the Kruskal-Wallis test and Dunn's test for pair-wise comparisons. p < 0.05 was considered statistically significant. RESULTS: Canals dried with only 1 paper point and obturated with the iRoot SP sealer (subgroup 2B) showed significantly higher bond strengths to the root canal wall compared to all other subgroups (p < 0.05), except for subgroup 1B (p > 0.05). CONCLUSIONS: The canal-drying technique influenced the adhesive bond strength between calcium silicate-based root canal sealers and the root canal wall.

Push-out bond strength of three calcium silicate cements to root canal dentine after two different irrigation regimes.

OBJECTIVES: The aim of this study was to compare the push-out bond strength of three calcium silicate cements to dentine after two different irrigation regimes. MATERIALS AND METHODS: One hundred eighty 2-mm-thick root sections were prepared. The sections were divided into three main groups (n = 60). In group A, the sections were immersed in 1 % NaOCl for 3 min. In group B, the sections were immersed in 17 % EDTA for 3 min followed by 1 % NaOCl for the same period of time. In group C (control group), no irrigation was applied to the sections. The samples from each group were divided into four subgroups (n = 15). In subgroups A1, B1 and C1, DiaRoot BioAggregate; in subgroups A2, B2 and C2, MTA-Angelus and in subgroups A3, B3 and C3, MM-MTA were mixed with hand-mixing. In subgroups A4, B4 and C4, MM-MTA was mixed with auto-mixing. The mixed cements were then placed into cavities with a carrier. The samples were submitted to the push-out test and were loaded. All the data were analysed with one-way analysis of variance and the Tukey HSD multiple comparisons (p < 0.05). RESULTS: There were no statistically significant differences between the irrigation regimes regardless of the used materials. The resistance to displacement in subgroup B4 was significantly greater than that presented by subgroups A3, B3 and C3 (p < 0.05) while not different than all other groups. CONCLUSIONS: Irrigation regimes had not affected the push-out bond strength of the calcium silicate cements. Also, strength of auto-mixed MM-MTA was similar to the other cements. CLINICAL RELEVANCE: The novel calcium silicate cements would be a potentially useful material in endodontic procedures with favourable properties.

Push-out bond strength between composite core buildup and fiber-reinforced posts after different surface treatments.

OBJECTIVE: The aim of this study was to evaluate the effects of different surface treatments on the pushout bond strength of fiber-reinforced posts to composite resin cores. MATERIALS AND METHODS: Twenty-five translucent glass fiber posts were divided into five groups according to surface treatment methods as follows: an untreated control group, a group coated with silicated alumina particles (Co-Jet system, 3M ESPE, St. Paul, MN), and three groups undergoing surface preparation with erbium:yttrium-aluminum-garnet (Er:YAG) laser under three different power settings (150, 300, and 450 mJ at 10 Hz for 60 sec at 100 µs duration). After surface treatment, fiber posts were built up to a dual cure composite resin core. All of the specimens were set and sectioned perpendicularly along the long axis of the post using a saw. Two discs (thickness of 2 mm) were obtained from each post-core sample; finally, each group consisted of 10 samples. For artificial aging, the specimens were stored in water (37°C) for 24 h and subjected to thermal cycling (5000 cycles, 5-55°C, and 30 sec dwell time). Pushout tests were performed using a universal testing machine at a crosshead speed of 0.5 mm/min. The pushout pressure values were measured in MPa and analyzed using one way analysis of variance (ANOVA) and Tukey's honestly significant difference (HSD) post-hoc test (p<0.05). Fiber post surface images were obtained using a scanning electron microscope (SEM). RESULTS: The bond strength values ranged between 14,949 and 23,879 MPa. The lowest values were observed in the groups treated with the Er:YAG laser at 150 mJ. Irradiation by the Er:YAG laser at 450 mJ affected the bond strength significantly (p<0.05). After Co-Jet sandblasting, the bond strength increased relatively (19,184 MPa). CONCLUSIONS: Er:YAG laser irradiation enhanced the bond strength of fiber-reinforced posts to composite resin cores depending upon the power applied; Co-Jet sandblasting also increased the bond strength.

Evaluation of apical filling after root canal filling by 2 different techniques.

OBJECTIVE: To determine the percent gutta-percha-filled area in the apical third of root canals after filling with 2 different root filling techniques. MATERIALS AND METHODS: Thirty extracted human lower premolars were instrumented with ProTaper rotary files (Dentsply Maillefer) and then randomly divided into 2 groups of 15 teeth each. The first group was filled using the single-cone technique with a tapered gutta-percha cone. The second group was filled with the lateral condensation technique. Horizontal sections were cut 2 and 4 mm from the apical foramen of each tooth. Photomicrographs of the apical surface of each cross-section were obtained at magnification x40. Digital image analysis was used to measure the overall area of the canal and the aggregate area occupied by gutta-percha; from these values, the percent gutta-percha-filled area was calculated. The data were compared by t test. RESULTS: The single-cone technique produced significantly greater percent gutta-percha filled area at 2 mm from the apex (p = 0.046), but there was no significant difference between the techniques at 4 mm from the apex (p = 0.17). CONCLUSIONS: These results suggest that the single-cone technique with tapered gutta-percha cones may yield better filling (measured as the percent gutta-percha-filled area) than the lateral condensation technique, at a level 2 mm from the apex.