Different biomechanical preparation protocols on the penetration and bond strength of the filling material to dentin

Abstract The aim of this study was to evaluate the influence of different instruments and mechanisms of agitation of the irrigating solution on the penetration by confocal laser scanning microscopy (CLSM), and the bond strength (BS) of the filling material to the dentin by push-out test. Human premolars were distributed in two experimental groups (n=30), according to the instrumentation system: ProTaper Next (PN) or XP-endo Shaper (XS) and three irrigation protocol (n=10): NaviTip (Nv), XP-endo Finisher (XF), passive ultrasonic irrigation/ XP-endo Finisher (PUIXF). The 2.5% NaOCl and 17% EDTA were the irrigating solutions used. The filling was performed using a lateral condensation technique, with AH Plus added to 0.1% rodhamine B. The roots were sectioned, obtaining 2 slices for each third of the root. The first slice was submitted to the sealer penetration analysis and the push-out test. The second slice was submitted to qualitative analysis (SEM) of the union interface. For the penetration (%) Tukey showed that PNXF (82.38±13.48), PNPUIXF (82.48± 12.02), XSXF (82.24±11.28) and XSPUIXP (86.23±10.45) presented the highest values, different (p<0.05) from PNNv (68.29±15.12) and XSNv (71.41±16.50). The BS (MPa) test evidenced that in the cervical third, PNPF (4.92±1.04) and XPSPF (5.03±0.70) obtained the highest values differing from the others groups (p<0.05). CSLM and SEM showed greater penetration of the sealer on the entire length of the root canal when the irrigation solution was stirred. In conclusion that the association PUI and XP-endo Finisher favored the penetration and bond strength of the filling material to the root dentin.

Resumo O objetivo neste estudo foi avaliar a influência de diferentes instrumentos e mecanismos de agitação da solução irrigadora na penetração e resistência de união (RU) do AH Plus à dentina. Pré molares humanos foram distribuídos em dois grupos experimentais (n=30), de acordo com o sistema de instrumentação: ProTaper Next (PN) ou XP-endo Shaper (XS) e de acordo com três protocolos de irrigação (n=10): NaviTip (Nv), XP-endo Finisher (XF), passive ultrasonic irrigation/ XP-endo Finisher (PUIXF). A irrigação do canal radicular foi realizada com NaOCl 2,5% e EDTA 17%. A obturação foi realizada por meio da técnica da condensação lateral, com AH Plus acrescido de rodhamina B 0,1%. As raízes foram seccionadas, obtendo-se 2 slices de 2,0 mm para cada terço radicular. O primeiro slice foi submetido a análise da penetração do cimento e ao teste de push-out e o segundo slice submetido a MEV para análise da interface de união. Para penetração (%) Tukey evidenciou que PNXF (82,38±13,48), PNPUIXF (82,48±12,02), XSXF (82,24±11,28) e XSPUIXF (86,23±10,45) apresentaram os maiores valores, diferentes (p<0,05) de PNC (68,29±15,12) e XPSC (71,41±16,50). Na RU (MPa) foi evidenciado que PNPF (4,92±1,04) e XPSPF (5,03±0,70), no terço cervical, obtiveram os maiores valores diferentes dos demais (p<0,05). MCVL e MEV evidenciaram maior penetração do cimento em toda extensão da parede do canal radicular inclusive nas regiões polares, quando foi realizada a agitação da solução irrigadora. Concluiu-se que a associação PUI e XP-endo Finisher favoreceu a penetração e resistência de união do material obturador à dentina radicular.

Removal of filling material using rotating or reciprocating systems with or without solvent: microCT analysis

Abstract This study evaluated by the efficacy of rotary and reciprocating systems to remove filling material by micro-CT. Sixty human canines were instrumented up to F3 by ProTaper Universal system and filled with AH Plus/ gutta-percha. Specimens were submitted to 1,200 thermal cycles, scanned by microCT SkyScan 1176 and randomly distributed in groups according to the filling material removal protocol (n = 10): ProTaper Universal, ProTaper Universal/xylol, ProTaper Next, ProTaper Next/xylol, Reciproc and Reciproc/xylol. After filling removal, specimens were analyzed by microCT to separately verify the presence of gutta-percha and sealer remnants. The data (mm3) were analyzed by two way ANOVA and Tukey´s test (5%). For the remaining gutta-percha, the use of xylol provided the highest values for Reciproc (7.60 ± 0.73), which was statistically different from the other groups (p < 0.05) that presented lower values and were statistically similar to each other (p > 0.05). For the remaining sealer, xylol provided the highest values (21.25 ± 6.94) different (p < 0.05) from the use of instruments alone (11.47 ± 9.45). ProTaper Next presented the lowest values (8.16 ± 1.37) for the remaining sealer, different (p < 0.05) from that of Reciproc (24.67 ± 6.32). The qualitative analysis revealed that all groups presented some remaining root filling material, with the highest volumes presented by Reciproc and Reciproc/xylol. In conclusion the rotary systems provided greater removal of filling material regardless of the use of xylol. The use of xylol negatively interfered with the action of the reciprocating system in the removal of the gutta-percha and sealer.

Push-out bond strength of different tricalcium silicate-based filling materials to root dentin

Abstract: The aim of this study was to evaluate the bond strength of different triccalcium silicate cements to retrograde cavity using a push out test. Thirty maxillary central incisors were shaped using #80 hand files and sectioned transversally. Root slices were obtained from the apical 4 mm after eliminating the apical extremity. The specimens were embedded in acrylic resin and positioned at 45° to the horizontal plane for preparation of root-end cavities with a diamond ultrasonic retrotip. The samples were divided into three groups according to the root-end filling material (n = 10): MTA Angelus, ProRoot MTA and Biodentine. A gutta-percha cone (#80) was tugged-back at the limit between the canal and the root-end cavity. The root-end cavity was filled and the gutta-percha cone was removed after complete setting of the materials. The specimens were placed in an Instron machine with the root-end filling turned downwards. The push-out shaft was inserted in the space previously occupied by the gutta-percha cone and push out testing was performed at a crosshead speed of 1.0 mm/min. There was no statistically significant difference in resistance to push out by the materials tested (p > 0.01). MTA Angelus and ProRoot MTA showed predominantly mixed failure while Biodentine exhibited mixed and cohesive failures. The tricalcium silicate-based root-end filling materials showed similar bond strength retrograde cavity.

Influence of Root Canal Filling Techniques on Sealer Penetration and Bond Strength to Dentin

Abstract The influence of root canal filling techniques on the penetration of AH Plus into dentinal tubules was evaluated using confocal laser scanning microscopy (CLSM) and the impact on the bond strength of the filling material on the root dentin was evaluated using the push-out test. Roots of the maxillary central incisors (n=40) were prepared with ProTaper Universal and assigned to four groups: lateral condensation, vertical compaction, modified Tagger hybrid and single cone. After root canal filling with gutta-percha and AH Plus, along with the addition of 0.01% fluorescein, the roots were cut into 2-mm slices. CLSM was performed on the first slice of each root third, followed by the push-out test. The second slice was analyzed under SEM. ANOVA demonstrated a statistically significant difference between the root canal filling techniques and the root thirds (p<0.05). For percent penetration, Tukey's test showed that the vertical compaction (91.77±13.51), lateral condensation (89.18±10.91) and modified Tagger hybrid (87.53±15.42) presented the highest values, which significantly differed (p<0.05) from those of the single cone (78.19±22.46). For bond strength (MPa), lateral condensation (3.42±0.54) and vertical compaction (3.47±0.53) had the highest values (p<0.05), while the modified Tagger hybrid (2.19±0.41) and single cone (0.54±0.21) had the lowest. In conclusion, the lateral condensation, vertical compaction and Modified Tagger's hybrid techniques resulted in greater penetration and bond strength to the intra-radicular dentin.

Resumo Avaliou-se a influência da técnica obturadora na penetração do cimento AH Plus nos túbulos dentinários, por meio de microscopia confocal de varredura a laser (MCVL), e o impacto na resistência de união do material obturador à dentina, por meio do teste de push out. Raízes de incisivos centrais superiores (n=40) foram preparadas com ProTaper Universal e distribuídas em 4 grupos: Condensação lateral, Compactação vertical, Híbrida de Tagger Modificada e Cone único. Após obturação com guta percha e AH Plus acrescido de fluoresceína 0,01%, as raízes foram seccionadas em slices de 2,0 mm. O primeiro slice de cada terço foi submetido à MCVL e, posteriormente, ao teste de push out. O segundo slice foi analisado em MEV. ANOVA demonstrou diferença estatisticamente significante para as técnicas obturadoras e terços radiculares (p<0,05). Para o percentual de penetração, Tukey evidenciou que compactação vertical (91,77±13,51), Condensação lateral (89,18±10,91) e Híbrida de Tagger Modificada (87,53±15,42) apresentaram os maiores valores, estatisticamente diferentes (p<0,05) da Cone único (78,19±22,46). Na resistência de união (MPa), Condensação lateral (3,42±0,54) e Compactação vertical (3,47±0,53) obtiveram os maiores valores, diferentes (p<0,05) da Híbrida de Tagger Modificada (2,19±0,41) e da Cone único (0,54±0,21), que teve os menores valores. Concluiu-se que as técnicas obturadoras Condensação lateral, Compactação vertical e Híbrida de Tagger Modificada propiciaram maior penetração e resistência de união à dentina intrarradicular.

Effect of root canal filling techniques on the bond strength of epoxy resin-based sealers

Abstract The aim of this study was to evaluate the effects of different root canal filling techniques on the bond strength of epoxy resin-based sealers. Sixty single-rooted canines were prepared using ProTaper (F5) and divided into the following groups based on the root filling technique: Lateral Compaction (LC), Single Cone (SC), and Tagger Hybrid Technique (THT). The following subgroups (n = 10) were also created based on sealer material used: AH Plus and Sealer 26. Two-millimeter-thick slices were cut from all the root thirds and subjected to push-out test. Data (MPa) was analyzed using ANOVA and Tukey's test (α = 0.05). The push-out values were significantly affected by the sealer, filling technique, and root third (p < 0.05). AH Plus (1.37 ± 1.04) exhibited higher values than Sealer 26 (0.92 ± 0.51), while LC (1.80 ± 0.98) showed greater bond strength than THT (1.16 ± 0.50) and SC (0.92 ± 0.25). The cervical (1.45 ± 1.14) third exhibited higher bond strength, followed by the middle (1.20 ± 0.72) and apical (0.78 ± 0.33) thirds. AH Plus/LC (2.26 ± 1.15) exhibited the highest bond strength values, followed by AH Plus/THT (1.32 ± 0.61), Sealer 26/LC (1.34 ± 0.42), and Sealer 26/THT (1.00 ± 0.27). The lowest values were obtained with AH Plus/SC and Sealer 26/SC. Thus, it can be concluded that the filling technique affects the bond strength of sealers. LC was associated with higher bond strength between the material and intra-radicular dentine than THT and SC techniques.

Rehabilitation of weakened premolars with a new polyfiber post and adhesive materials.

Background: Polyfiber posts used inside the root canal can help to restore the fracture resistance of weakened premolars. Aim: To assess the fracture resistance of endodontically treated premolars restored with different techniques, including the new polyfiber post (Spirapost). Materials and Methods: One hundred superior premolars were distributed into 10 groups (n = 10): Sound teeth (G1‑positive control) and experimental (G2 to G10), which received MODP cavities and canal treatment. Groups were restored as follows: G2 ‑ unrestored (negative control); G3 ‑ microhybrid resin (MR); G4 ‑ flowable resin (FR) + (MR); G5 ‑ glass fiber post (Reforpost) + MR; G6 ‑ Reforpost + FR + MR; G7 ‑ polyethylene fiber (Ribbond) + MR; G8 ‑ Ribbond + FR + MR; G9 ‑ polyfiber post (Spirapost) + MR and G10 ‑ Spirapost + FR + MR. After 24 h, the specimens were loaded until fracture. Data were analyzed by ANOVA and Tukey’s test (P < 0.05). Results: Premolars restored with Spirapost (G9 and G10) provided the highest fracture strength (P < 0.05), similar to sound teeth (G1), regardless of the composite resin. Intermediate values were achieved by G3, G4, G5, G6, G7, and G8, which were similar (P > 0.05) and different from the others (P < 0.05). Inferior values were found in G2 (P < 0.05). Conclusion: Fracture resistance of premolars with MODP cavities and endodontic access was recovered with the direct rehabilitation with Spirapost, regardless of the type of composite resin.