Objective: The present study aimed to evaluate the bond strength of Sure-Seal Root as a new bioceramic-based sealer, and compare it with other sealers, including an epoxy resin-based sealer (AH-Plus), zinc oxide eugenol (ZOE) and a mineral trioxide aggregate-based sealer (MTA Fillapex). Methods: In this in vitro study, 40 extracted mandibular premolars were randomly assigned into 4 groups (n=10) according to the type of sealer applied as follows: Group 1: AH-Plus, Group 2: MTA-Fillapex, Group 3: Sure-Seal Root, and Group 4: ZOE. The canals were prepared and obturated with gutta-percha and the corresponding sealer. The samples were sectioned into horizontal segments, and the push-out bond strength was determined using a universal testing machine at the coronal, middle, and apical root thirds. The data were analyzed by repeated measures ANOVA, and the significance level was set at P<0.05. Results: There were no significant differences in the push-out bond strength between groups in the coronal third (P>0.05). In the middle third, AH-Plus exhibited significantly greater bond strength compared to Sure-Seal Root and ZOE sealers (P<0.05), whereas MTA-Fillapex was not significantly different from the other groups (P>0.05). In the apical third, both AH-Plus and MTA-Fillapex showed significantly greater push-out bond strength than Sure-Seal Root and ZOE sealers (P<0.05). Conclusions: AH-Plus sealer exhibited the highest and ZOE showed the lowest bond strength. Sure-Seal Root indicated promising bond strength results when compared to ZOE and MTA-Fillapex. The push-out bond strength of all sealers to dentin increased from the coronal to the apical third.

Statement of Problem: Calcium hydroxide which is commonly used as an intracanal medicament, changes the pH of dentin and periradicular tissues to an alkaline pH. In some clinical situations, endodontic reparative cements like calcium enriched mixture cement are used after calcium hydroxide therapy. However, the alkaline pH may affect the physical properties of this cement.Objectives: This study was designed to evaluate the effect of alkaline pH on the push-out bond strength of calcium enriched mixture.Materials and Methods: 80 root slices were prepared from single-rooted human teeth and their lumens were instrumented to achieve a diameter of 1.3mm. Calcium enriched mixture (CEM) was mixed according to the manufacturer’s instruction and introduced into the lumens of root slices. The specimens were then randomly divided into 4 groups (n=20) and wrapped in pieces of gauze soaked in synthetic tissue fluid (STF) buffered in potassium hydroxide at pH values of 7.4, 8.4, 9.4, or 10.4. The samples were incubated for 4 days at 37oC. The push-out bond strengths were then measured using a universal testing machine. Failure modes were examined under a light microscope at×20 magnification. The data were analyzed using one-way analysis of variance and Tukey’s post hoc tests.Results: The greatest (1.41±0.193 MPa) and lowest (0.8±0.06 MPa) mean push-out bond strengths were observed after exposure to pH values of 7.4 and 8.4, respectively. There were significant differences between the neutral group and the groups with pH of 8.4 (p=0.008) and 10.4 (p=0.022). The bond failure was predominantly of cohesive type for all experimental groups.Conclusions: Under the condition of this study, alkaline pH adversely affected the push-out bond strength of CEM cement.

Background: Trioxide Aggregate (MTA) has been widely used in root canal therapy. MTA has been mixed with chlorhexidine to increase its antimicrobial effect.Objectives: The aim of this study was to evaluate the effect of chlorhexidine (2%) on push-out bond strength of Mineral Trioxide Aggregate (MTA).Materials and Methods: Sixty dentin disks with a thickness of 1.5±0.2 mm and lumen size of 1.3 mm were prepared. Dentin disks were randomly divided into four groups (n=15), and their lumens were filled with MTA mixed with distilled water (groups 1 and 3) or with chlorhexidine 2% (groups 2 and 4). Specimens were incubated at 37oC for 3 days (groups 1 and 2) or 21 days (groups 3 and 4). bond strengths of the MTA-treated dentin surfaces were evaluated using a universal testing machine, and bond failure on the disks was examined by light microscope. Data was analyzed using Kruskal-Wallis H test (P=0.976).Results: There were no statistically significant differences between all the experimental groups. The mode of bond failure was predominantly mixed for distilled water groups and cohesive for CHX groups.Conclusions: This study suggested that chlorhexidine had no negative effect on the bond strengths of MTA-treated dentin.

Background. This study investigated the effect of the thickness of two resin cements on push-out bond strength of fiber posts to root dentin. Methods. Sixty decoronated single-rooted teeth were endodontically treated. The specimens were then randomly allocated to two groups (n=30); group 1: drill size 90 w, matching the size of fiber posts used; group 2: drill size 110, larger than the posts. The specimens in each group were divided into 2 subgroups (n=15); subgroup SE, in which the posts were cemented with self-etch Panavia F2. 0 and subgroup SA, in which self-adhesive Panavia cement was used. After 72 hours, 2 slices with 1 mm of thickness were prepared from the mid-root of each specimen. push-out bond strength test was performed in a uni-versal testing machine at a crosshead speed of 1 mm/min. Data were analyzed with two-way ANOVA and t-test. Results. The mean bond strengths of the posts cemented in matched-size spaces for SE and SA groups were 4. 02± 1. 6 and 4. 12± 2. 3 MPa, respectively. For posts cemented in oversized spaces, the values were 4. 9± 2. 3 and 2. 8± 1. 3 MPa, respectively. In matched-size spaces, there was no significant difference between the two groups. Conclusion. The results of this study suggested that increasing the cement thickness would reduce the bond strength of fiber posts to root dentin when self-adhesive cements are used; however, self-etch adhesives were not affected.

Introduction: Bioactive endodontic sealers have been developed to improve the quality of root canal obturation. Endo Sequence Bioceramic (BC) Sealer is amongst calcium silicate based materials recently developed for permanent root canal filling. The objective of this study was to evaluate the bioactivity of BC Sealer and its micro push-out bond strength to dentin compared to AH-Plus (AH) sealer.Methods and Materials: To perform the micro push-out test, 24 root canals of mandibular premolars were instrumented and divided into two groups (n=12). Each root was cut into 4 slices and lumens of the canals were filled with the sealers and submitted to micro push-out test. Failure mode was assessed using scanning electron microscopy (SEM). Bioactivity of BC sealer was investigated with scanning electron microscopy/energy-dispersive X-ray (SEM/EDS) and X-ray diffraction (XRD). Bioactivity assessments were reported descriptively. bond strength data were analyzed by parametric test (a=5%).Results: In micro push-out test AH had higher bond strength mean values (16.29 MPa) than BC sealer (9.48 MPa) (P<0.05). Both groups had low amount of adhesive failure. SEM showed the presence of a mineral precipitate after 30 days and EDS analysis showed that those precipitates have high proportion of Ca. XRD showed peaks of crystalline phases of calcium carbonate compatible with the bioactivity.Conclusion: BC sealer showed indications of bioactivity and lower bond strength to dentine compared to AH.