Post space debridement in oval-shaped canals: The use of a new ultrasonic tip with oval section

This study evaluates the effect on post space debridement in oval-shaped canals of an experimental ultrasonic tip with oval section (Satelec) compared with a circular ultrasonic tip (KaVo). Thirty teeth with an oval-shaped canal were endodontically treated and obturated and then randomly divided into 3 groups (n = 10) according to the procedure used for post space debridement: Satelec tip, Largo #2 drill + KaVo file, and Largo #2 drill + water. Debris and dentin tubules were evaluated by assigning scores to scanning electron microscope post spaces images; lower scores corresponded to fewer debris and higher number of open tubules. The Satelec group showed significantly lower debris and open tubules scores than KaVo group (p < .05) and control group (p < .05), which differed significantly between each other (p < .05). Also the debris and open tubules scores in different post space regions differed significantly among the experimental groups (p < .001). The oval ultrasonic tip resulted in a better post space debridement than a circular ultrasonic tip in oval-shaped canals

Influence of ultrasound application on inlays luting with self-adhesive resin cements

The study was aimed at assessing the influence of the cement manipulation and ultrasounds application on the bonding potential of self-adhesive resin cements to dentin by microtensile bond strength testing and microscopic observations of the interface. Fifty-six standardized mesio-occlusal class II cavities were prepared in extracted third molars. Class II inlays were made using the nano-hybrid resin composite Gradia Forte (GC Corp, Tokyo, Japan), following the manufacturer's instruction. The sample was randomly divided into two groups (n = 28) according to the luting technique. Half of the specimens were luted under a static seating pressure (P), while the other ones were cemented under vibration (V). The inlays were luted using the following self-adhesive resin cements: G-Cem (G, GC Corp., Tokyo, Japan) Automix (GA) and Capsule (GC); RelyX Unicem (RU, 3 M ESPE, Seefeld, Germany) Clicker (RUC) and Aplicap (RUA). Microtensile sticks and specimens for scanning electron microscope (SEM) observations were obtained from the luted teeth. The interfacial strengths measured for the cements under static pressure or ultrasonic vibration were [median (interquartile range)]: GC/V 4 (2.3-7.9); GC/P 6.8 (4.1-10.1); GA/V 3 (1.9-6.7); GA/P 1.9 (0-5.1); RUC/V 6.6 (4.6-9.8); RUC/P 4.1 (1.8-6.4); RUA/V 6.2 (2.4-10.4); RUA/P 3.4 (0-5.4). The cement formulation influenced dentin bond strength of G. RU bond strength was affected by the luting technique. SEM analysis revealed a homogeneous structure and reduced porosities for both cements as a result of ultrasonic vibration. RU benefited from the application of ultrasounds, while GC achieved higher bond strengths than GA

Adhesion between fiber posts and resin luting agents: A microtensile bond strength test and an SEM investigation following different treatments of the post surface

Purpose: (1) To evaluate the interfacial strength between FRC Postec posts and three luting agents (Multilink, Variolink 11, and MultiCore Flow) following different surface treatments, and (2) to observe the effect of sandblasting (Rocatec Pre) on the surface morphology of methacrylate-based fiber posts. Materials and Methods: The posts received one of the following surface treatments: (1) sandblasting, (2) sandblasting + silanization, (3) silanization or (4) no treatment. The three luting agents were bonded to the post and the post-cement bond strength was evaluated with the microtensile test. SEM observation of sandblasted and nontreated posts was performed. Post-cement interfaces were also evaluated. Data were statistically analyzed with two-Way ANOVA with post treatment and luting agent as factors. Tukey's test was applied for post-hoc comparisons. Results: Post treatment and the interaction between type of luting agent and type of post treatment were significant factors for bond strength (p lt 0.001). The type of luting agent did not significantly influence bond strength (p = 0.07). Sandblasting + silanization performed better than sandblasting or no treatment (p lt 0.001). Silanization resulted in significantly higher bond strengths than no treatment (p = 0.045). No differences were detected between sandblasting + silanization and silanization. SEM observation revealed an increased surface roughness and exposure of fibers in sandblasted posts. Conclusion: Silanization was confirmed to be a reliable method for improving the bond strength of resin luting agents to fiber posts. Bond strength of resin luting agents to fiber posts was not influenced by the type of luting agent. The sandblasting procedure modified the methacrylate-based post surface texture

Post space cleaning using a new nickel titanium endodontic drill combined with different cleaning regimens

This study compared the effect of two drills and five cleaning regimens on post space debridement. One hundred extracted premolars were instrumented and obturated with warm vertical compaction of gutta percha. The teeth were divided into two groups according to the drill used to remove gutta percha/sealer and for post space preparation: a Largo drill (Largo; Dentsply, St Quentin en Yvelines, France) or a MTwo-PF drill (Sweden&Martina, Due Carrare, Padova, Italy). The following cleaning regimens were used: EDTA, ultrasonics, ultrasonics + EDTA, phosphoric acid, and distilled water. Scanning electron microscopic images of the post spaces were taken, and the presence of debris and of open dentin tubules were evaluated. The ultrasonics + EDTA, phosphoric acid, and EDTA groups were comparable in open tubules scores for both drills and in debris scores after the use of MTwo-PF (p > 0.05). The ultrasonics and control groups performed significantly worse (p lt 0.05). The MTwo-PF drill resulted as effective as the Largo drill in obtaining a good post space cleaning, especially when followed by ultrasonics + EDTA irrigant regimen

The effect of sandblasting on adhesion of a dual-cured resin composite to methacrylic fiber posts: Microtensile bond strength and SEM evaluation

Objectives: To evaluate the influence of different surface treatments on the microtensile bond strength of a dual-cured resin composite to fiber posts. Methods: Thirty-two glass methacrylate-based fiber posts (GC Corp.) were used in the study. Posts were divided into two groups, according to the surface pretreatment performed. Group 1: sandblasting (Rocatec-Pre, 3 M ESPE). Group 2: no pretreatment. In each of the two groups posts received three types of additional "chair-side" treatments. (1) Silane application (Monobond S, Ivoclar Vivadent); (2) adhesive application (Unifil Core self-etching bond, GC); (3) no treatment was performed. A dual-cured resin composite (Unifil Core, GC) was applied on the posts to produce cylindrical specimens. Specimens were cut to obtain microtensile sticks that were loaded in tension at a cross-head speed of 0.5 mm/min until failure. The morphology of the post/composite interface and the post surface morphology were evaluated under SEM. Statistical analysis was performed with two-way ANOVA and Tukey test for post hoc comparisons (p lt 0.05). Results: Post surface pretreatment did not prove to be a significant factor in post-composite bond strength (p = 0.08), whereas "chair-side" treatment modalities and the interaction between pretreatment and treatment showed a significant influence on bond strength (p lt 0.001). When no "chair-side" treatment was performed, bond strength was significantly higher on sandblasted posts. Additional adhesive application resulted in significantly lower bond strength on sandblasted posts. When no pretreatment was performed, silane application resulted in higher bond strength than adhesive application. Conclusions: Sandblasting may give an increase in microtensile strength to methacrylate-based glass fiber posts, eliminating the need for additional "chair-side" treatments. Reducing the number of clinical steps could contribute to simplify the clinical procedures